13 Clinical uses of growth factors IAN DAVIS GEORGE MORSTYN

The haemopoietic system is under the control of growth factors produced not only at sites of blood cell production but in all tissues. They combine in a complex network to maintain steady-state haemopoicsis and to mediate the response to unexpected demands on the system by increasing production in one or more haemopoietic compartments. The first haemopoietic growth factor to be isolated and cloned was erythropoietin (EPa) (Miyake et ai, 1977), a glycoprotein which was found in the urine of patients with aplastic anaemia. Over the next 10 years several other haemopoietic growth factors were discovered, cloned and produced in sufficient quantities by recombinant techniques to allow clinical as well as in vitro and in vivo animal studies. The factors which have activity on the haemopoietic system and have entered clinical trials include granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), monocyte colony-stimulating factor (M-CSF, CSF-l), interleukin-J (IL-3, MultiCSF), interleukin-Z (IL-2), interleukin-4 (IL-4) and the monokine interleukin-l (IL-l). Since all of these agents are under clinical trial, their properties will be reviewed. Other potential growth factors which as yet have not been studied as extensively but will enter clinical development in the near future will also be mentioned. Table 1 contains a summary of the potential clinical uses for GM-CSF and G-CSF. Clinical studies with these two factors commenced in 1986 and this review will describe the results of preclinical and clinical investigations Table 1. Potential clinical uses for G-CSF and GM-CSF. Amelioration of neutropenia due to chemotherapy Prophylaxisagainst infection and mucositis Salvage therapy for infections in neutropenic patients Adjunct to antibiotic therapy Therapy of neutropenia in other conditions Autologous bone marrow transplantation Peripheral blood progenitor cell mobilization AIDS (in conjunction with antiretroviral drugs or erythropoietin) Direct anticancer effects, e.g, acute myeloblastic leukaemia Increase in dose intensity of chemotherapy, with possibleimprovement in remissionrates Combination therapy with other growth factors and cytokines

Bailliere's Clinical HaematologyVol. 5, No.3, July 1992 ISDN0-7020-1628-4

753 Copyright © 1992, by BailliereTindall All rights of reproduction in any form reserved

754

I. DAVIS AND G. MORSTYN

involving them. G-CSF was approved in 1990for the prevention of chemotherapy induced neutropenia. GM-CSF was approved for use in autologous marrow transplantation in patients with non-myeloid malignancies. G-CSF Preclinical studies

Studies in mice (Fujisawa et al, 1986; Kobayashi et ai, 1987; Shimamura et ai, 1987) and monkeys (Welte et ai, 1987) have demonstrated that G-CSFis able to induce a neutrophilia in normal animals and to accelerate neutrophil recovery after 5-ftuorouracil or total body irradiation. Pretreatment levels of neutrophils were achieved within 10 days of beginning treatment after aplasia-inducing doses of cyclophosphamide were given to monkeys (Welte et ai, 1987). When G-CSF was commenced before chemotherapy, the level of neutropenia was more profound, but recovery was not affected. This may indicate that cells are induced into cell cycle by G-CSF and are therefore susceptible to the cytotoxic drug. Tritiated thymidine labelling studies neutrophils were used to investigate the kinetics of granulopoiesis in humans and mice after the administration of G-CSF (Lord et ai, 1989, 1991; see also Chapter 3). These showed that granulopoiesis was increased at all stages, predominantly at the myeloblast level. Acceleration of maturation and release was also apparent, but no change was observed in the half-life of circulating neutrophils, nor was any organ sequestration noted. Neutrophil function appears to be at least preserved and possibly enhanced in patients receiving G-CSF. Chemotactic ability and nitroblue tetrazolium reduction is increased in neutrophils produced by G-CSF (Welte et ai, 1987), which also provides protection against lethal inocula of various pathogens, including bacteria and fungi in mice, and appears to synergize with antibiotics against Pseudomonas aeruginosa (Ono et aI, 1988). Oxygen release and neutrophil C3bi expression is normal in patients receiving chemotherapy and G-CSF (Ohsaka et aI, 1989). Toner et al (1988) have suggested that tissue migration of neutrophils, as assessed by skin chamber techniques, is preserved, in contrast to GM-CSF (Peters et al, 1988), although it is not clear if this method of assessment accurately indicates the ability of neutrophils to migrate into other tissues. Clinical studies with G-CSF

Phase 1 studies Phase I studies demonstrated that G-CSF is effective in elevating neutrophil counts in a dose dependent fashion, whether given by continuous intravenous infusion, short intravenous infusion, or subcutaneous infusion (Bronchud et al, 1987; Lieschke et aI, 1990). In contrastto GM-CSF, G-CSF is remarkably free of side-effects. The main adverse effects are bone pain in 20% of patients, elevation of alkaline phosphatase and lactate dehydrogenase, elevation of

CLINICAL USES

755

serum urate, and splenic enlargement in children with chronic neutropenia. These problems are usually minor, and the bone pain is easily controlled with paracetamol/acetaminophen. There has been one report of Sweet's syndrome (acute febrile neutrophilic dermatosis) in a patient with hairy cell leukaemia and pre-existing vasculitis involving the skin (Glaspy et aI, 1988). Neutropenia after cancer chemotherapy

Before an understanding of the role and mechanisms of action of G-CSF and GM-CSF could be reached, further investigation had to be undertaken as to the pathophysiology of neutropenia, and in particular neutropenic sepsis. It was not clear whether the problem in these patients was due simply to inadequate numbers of neutrophils, or whether their neutrophils were also qualitatively deficient. It appears that infections in such patients are due to a combination of these factors (Pickering et al, 1978). Furthermore, neutropenic patients often develop fevers without an obvious source of infection and without microbiological confirmation of infection. There is no doubt that neutropenic patients are at increased risk of death from infection, and that as higher doses of chemotherapy, or longer courses, or combinations of chemotherapy and radiotherapy are used, the risk is further increased (for review see Lieschke and Morstyn, 1990). The question of neutropenia following cancer chemotherapy has been recently reviewed (Davis and Morstyn, 1991; Lieschke and Morstyn, 1990, 1992). As shown in Table 2, in many clinical settings G-CSF has been shown to shorten significantly the duration of neutropenia. This has translated into patient benefits in the form of fewer infections (Crawford et al, 1991), reduced mucositis (Gabrilove et aI, 1988; Morstyn et aI, 1990), less time in hospital (Crawford et al, 1991), and an ability to administer higher doses of chemotherapy (Bronchud et al, 1989). To confirm that the reduction in neutropenia produced by G-CSF resulted in clinical benefit it was important to carry out a placebo controlled randomized study. This was done by Crawford et al using cyclophosphamide, doxorubicin and etoposide in small cell lung cancer. These cytotoxics were chosen as they are commonly used in the treatment of many cancers. Small cell lung cancer was chosen as a model of a cancer that responds to chemotherapy and whose treatment is complicated by infections. The study drug was given for each cycle and was unblinded for episodes of febrile neutropenia. These patients were subsequently treated with open label G-CSF. There was a 50% reduction in the rate of febrile neutropenia for those patients on G-CSF, and consequently less hospitalizations and antibiotic usage. Patients on placebo who crossed over to G-CSF after febrile neutropenia were able safely to receive full dose chemotherapy with G-CSF support. We are currently involved in a phase III trial to assess whether the addition of G-CSF to a standard antibiotic protocol in the setting of chemotherapy induced febrile neutropenia provides any clinical benefit. G-CSF has received approval for use in preventing infection after chemotherapy in the USA and several major European countries.

Randomized

Shortened period of neutropenia, enhanced monocyte recovery, no change in platelet recovery Shortened period of neutropenia

N

N

R

Various malignancies

Breast, ovary

Small cel1lung cancer

N

Glycogen storage disease type Ib

Various haematological conditions Myelodysplastic syndromes N

N

Cyclic neutropenia

Threefold increase in neutrophil count Resolution of cytogenetic abnormalities while on treatment

Shortening of cycle Increased amplitude of BFU·E andGM-CFC Increase in neutrophils

Neutropenia not related to myelotoxic chemotherapy Severe chronic neutropenia N Increase in ANC, not eosinophils (Kostmann's syndrome) Increase in ANC Severe chronic neutropenia N or cyclic neutropenia

Shortened period of neutropenia

Shortened period of neutropenia

N

Bladder

Resolution of infections

Dale et al (1990)

Decrease in fevers, mouth ulcers, bacterial infections, lymphadenopathy

Ohyashiki et al (1989)

Welte et al (l990b)

Migliaccio et al (1990)

Welte et al (199Oa)

Crawford et al (1991)

Bronchud et al (1989)

Neidhart et al (1988)

Gabrilove et al (1988)

Bronchud et al (1987)

Reference

Fewer infections

Increased dose of chemotherapy delivered 50% reduction in febrile neutropenia Less time in hospital Less antibiotic use Fewer culture-positive infections Given for 6 cycles

Fewer infections Less antibiotic use Reduced severity and incidence of mucositis Fewer days on antibiotics Able to receive next chemotherapy cycle

Selected clinical benefits

Table 2. Selected clinical studies involving G-CSF. Selected biological results

Reduction ofneutropenia after chemotherapy for solid tumours Small cell lung cancer N Shortened period of neutropenia

Clinical situation

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R

N

Lymphoma

Relapsed or refractory acute leukaemia

Aplastic anaemia (in children)

Increase in neutrophil count

Increase in neutrophils while on therapy Amelioration of fall in ANC with chemotherapy Increase in oxygen radical release with FMLP Shortened period of neutropenia No improvement in platelet recovery

N

Phase I studies Chemotherapy

HIV infection

N

N

Peripheral blood progenitor cell mobilization Autologous bone marrow transplantation plus PBPC

Hodgkin's disease

Early transient fall in ANC, then rise

Increase in BFU-E Fall in TIBC and ferritin Fall in endogenous erythropoietin

Increase in PBPC recovery with G-CSF Kinetics of neutrophil recovery similar to ABMT and G-CSF Rapid platelet recovery

Shortened period of neutropema

High-dose chemotherapy and autologous bone marrow transplantation Non-myeloid malignancies N Shortened period of neutropenia

N

Myelodysplastic syndromes

Less antibiotic use Trends to fewer febrile days, days in isolation, days on TPN, days in hospital Shorter febrile episodes Less severe mucositis

Reduction in infections No difference in regrowth of blasts Relapse rate unchanged Trend to increased remission rate No difference in number of febrile days

Progression to myeloid leukaemia in 3/18 patients

Morstyn et al (1988)

Miles et al (1990)

Sheridan et al (1990)

Taylor et al (1989)

Sheridan et al (1989)

Kojima et al (1991)

Ohno et al (1990)

Ohsaka et al (1989)

Negrin et al (1990)

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n

N

N

Various cancers

Selected clinical benefits

Fossat et al (1990)

Toner et al (1988)

Bronchud et al (1988)

Ohsaka et al (1989)

Layton et al (1989)

Morstyn et al (1988, 1989b)

Lord et al (1989)

Lindemann et aI (1989)

Reference

N, non-randomized; R, randomized; ANC, absolute neutrophil count; FMLP, N-formyl-methionyl-Ieucinyl-phenylalanine; TIBC, total iron binding capacity; TPN, total parenteral nutrition.

N

N

Neutrophil function Lymphoma on chemotherapy Small cell lung cancer on chemotherapy Patients receiving G-CSF

N

N

Normal neutrophil oxygen release and C3bi expression Neutrophils at least as active as in normal patients Normal skin chamber neutrophil migration Increased antibacterial activity against Pseudomonas aeruginosa

N

Breast cancer, no chemotherapy Advanced cancer

Various malignancies

Fall in ANC over first 10min, then rise Transient fall in platelets to day 10, then rise Increase in oxygen radical production Increase in neutrophil proliferation, maturation, and release i.v. or subcutaneous routes effective Subcutaneous better than divided i.v. doses Prechemotherapy G-CSF not necessary for benefit Supranormal elevation of neutrophils not necessary Delay in commencement of G-CSF not harmful Possible clearance of G-CSF by mature neutrophils

N

Various malignancies, no chemotherapy

N

Selected biological results

Randomized

Clinical situation

Table 2. (cont.)

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CLINICAL USES

759

Neutropenia due to other causes

In Kostmann's syndrome, G-CSF has been shown to increase the neutrophil count (Welte et al, 1990a). In cyclic neutropenia, the cycle length can be shortened, and increased amplitude of the erythroid burst-forming unit (BFU-E) and granulocyte-macrophage colony-forming cells (GM-CFC) are observed (Migliaccio et al, 1990). In a patient with glycogen storage disease type Ib, G-CSF rapidly increased the neutrophil count with a subsequent clinical improvement in respect of infections (Wang et al, 1990). Continued G-CSF therapy maintained her clinical improvement and the patient remained free of infections. The only side-effect was splenomegaly. Although this might be considered a rare occurrence in humans, and only reported in children with severe chronic neutropenia, recombinant human G-CSF in mice results in migration of progenitors from the bone marrow and a very significant increase in both progenitors and overall cellularity ofthe spleen (Molineux et aI, 1990a; Pojda et aI, 1990). Whether extramedullary haemopoiesis is the cause of splenomegaly in children with severe chronic neutropenia is unclear. Welte et al (1990b) also report improvement in neutrophil counts and resolution of infections in patients with this disorder maintained on G-CSF. The benefits of G-CSF in severe chronic neutropenia have been sustained for more than 3 years (D. Dale, personal communication). Myelodysplastic syndromes and aplastic anaemia

The myelodysplastic syndromes are a heterogeneous group of disorders, some of which have characteristic cytogenetic abnormalities involving the long arm of chromosome 5 on which the gene for GM-CSF is found (Wong et aI, 1985). Patients are at risk of death from bleeding, infection or transformation into acute leukaemia, and anaemia is a cause of significant morbidity. In these conditions, neutrophil counts can be increased by G·CSF with an increase in GM-CFC in the bone marrow (Ohyashiki et aI, 1989; Nagler et al, 1990), without increasing clonal proliferation. Cytogenetic abnormalities may disappear during treatment, only to reappear on cessation of G-CSF (Ohyashiki et aI, 1989), possibly indicating selective stimulation of normal clones of haemopoietic cells. Negrin et al (1990), treating 18 patients with G-CSF, found improved neutrophil counts in 16 of them but they all returned to baseline on cessation of theralY' A reduced risk of infection was noted when neutrophils were> 1.5 x 10 /litre, Three patients, however, progressed to myeloid leukaemia during treatment. Kojima et al (1991) found that G-CSF led to an increase in neutrophil counts in children with aplastic anaemia for the duration of therapy, but that counts retun~ed to baseline on cessation of G-CSF. G-CSF and GM-CSF may Increase neutrophil counts in patients with myelodysplasi~ or aplastic anaemi~ but thi.s is not sustained, and it may be that G-CSF will be more use~l m.treating th~se patients during acute infections. For my.elodysplast.lc patients, the fisk of stimulating trans. formation to myeloid leukaemia remains undefined.

760

I. DAVIS AND G. MORSTYN

Acute leukaemia G-CSF has been used in both lymphoblastic and myeloblastic leukaemias (Ohno et ai, 1990). Again, neutrophil recovery was accelerated and a reduction in infections was seen in both types of leukaemia. There was a trend towards an increased remission rate in the group receiving G-CSF, but this did not reach statistical significance. There was no difference between the groups with respect to platelet recovery, relapse rate or febrile days. No increase in the regrowth of myeloblasts was observed in the group receiving G-CSF, indicating that it may be safe to use the drug in this group, as long as chemotherapy is not withheld. Clearly there is no contraindication to the use of G-CSF in acute lymphoblastic leukaemia, and G-CSF may be expected to find a major role in the treatment of these patients.

Autologous bone marrow transplantation (ABMT) ABMT has been undertaken using G-CSF for various non-myeloid malignancies. G-CSF has produced significant reductions in the period of neutropenia, with direct patient benefits being less usage of antibiotics, shorter febrile episodes and less severe mucositis, with trends towards fewer febrile days, fewer days requiring reverse barrier nursing, fewer days on parenteral nutrition, and fewer days in hospital (Sheridan et al, 1989;Taylor et aI, 1989).

Peripheral blood progenitor cell mobilization The collection of peripheral blood progenitor cells (PBPC) is a potentially very useful technique. Sheridan et al (1990) demonstrated that G-CSF isvery effective at mobilizing progenitor cells into the peripheral blood where they may be collected with high efficiency using leukapheresis. When infused together with autologous bone marrow cells following high-dose chemotherapy, neutrophil recovery follows similar kinetics to those of ABMT alone plus G-CSF, although recovery may be slightly accelerated. Of great importance however is the observation that platelet recovery is greatly accelerated with patients achieving platelet counts > 20 X 1091litre at a median of 9 days, and> 50 X 109/litre at a median of 14days. This has marked clinical significance in terms of independence from platelet transfusions. Clearly earlier progenitor cells than GM-CFC are being mobilized in this setting, although these have not been well characterized, and the mechanism of G-CSF action in releasing these cells is not clear. These cells do not always express CD34 but there is evidence from studies in mice that circulating progenitors induced by G-CSF in mice are both relatively primitive and have good long-term transplantation potential (Molineux et al, 1990b). There is a secondary fall in platelet counts after several weeks in a few patients who appear to have received suboptimal numbers of progenitors. In these patients a subsequent rise in platelets isseen, which suggests that the initial early rise in platelets may be due to the PBPC and the secondary rise to marrow engraftment, although this has not been confirmed.

CLINICAL USES

761

Human immunodeficiency virus (HIV)-l infection There has been considerable interest in the use of G-CSF, particularly in combination with other growth factors such as EPO, in patients with HIV-l infection, especially those with marrow suppression due to antiretroviral drugs such as zidovudine (AZT) or antiviral drugs such as ganciclovir. G-CSF alone can increase BFU-E (Miles et aI, 1990), and EPO can ameliorate the anaemia caused by AZT, thus reducing transfusion requirements (Levine et aI, 1989). The combination of the two may well reduce the anaemia and neutropenia observed with AZT or ganciclovir, without the risk observed with GM-CSF of activating monocytes/macrophages which may carry HIV-l (Perno et aI, 1989).

GM-CSF

Preclinical studies: biology and efficacy In vitro studies indicate that GM-CSF acts on both mature cells and immature cells of the granulocyte-macrophage lineage, causing proliferation of progenitor cells (Metcalf, 1984) and differentiation of more mature cells (Metcalf and Burgess, 1982). GM-CSF can activate many functions of phagocytic cells, including chemotaxis, adhesion, phagocytosis, degranulation, superoxide anion generation, antibody-dependent cell mediated cytotoxicity and antiparasitic activity. These effects have recently been extensively reviewed (Cebon and Morstyn, 1990). In mice, GM-CSF given intraperitoneally has the effect of increasing granulopoiesis, with accumulation of mature neutrophils and monocytes being observed in the liver and spleen (Metcalf et aI, 1987). Human GM-CSF given to non-human primates causes a marked leukocytosis which is maintained up to 28 days, giving, without adverse effects, increases in neutrophils, eosinophils, monocytes and lymphocytes (Donahue et aI, 1986a). A mild reticulocytosis also develops. Both CHO-cell-derived and Escherichia coli-derived human GM-CSF give similar effects when given to monkeys intravenously and subcutaneously, although the subcutaneous route is more effective in causing leukocytosis (Mayer et al, 1987). GM-CSF is effective in both normal animals and those subjected to myelotoxic treatment. In mice given recombinant murine GM-CSF following melphalan, neutropenia is shortened and there is a marked reduction in the death of mice during neutropenia (Douer et aI, 1987). Depletion of progenitor granulocyte-~~crophagepools in the marrow and spleen occurs earlier in the group recervmg GM-CSF, but this effect does not persist. The ability o~ GM-C:S~ to enhance granulocyte and macrophage proliferatiOJ:~ and differentiation suggested a role in the therapy of myeloid leuk~emlas. and myel~d~~plastic .syn.d~omes. Its effects on neutrophil function raised the possiblhty of using It 10 neutropenic patients to increase neutrophil numbers and stimulate neutrophil function, and perhaps to augment monocyte-macrophage bactericidal or tumouricidal activities.

762

I. DAVIS AND G. MORSTYN

Other possible uses suggested by the preclinical work include a role in adjunctive therapy for infections, and the use of GM-CSF in combination with other cytokines to achieve clinical responses in particular situations, for example in aplastic anaemia, bone marrow transplantation, and in patients with acquired immunodeficiency syndrome (AIDS). Clinical studies Biology and efficacy

Early studies with GM-CSF were hampered by the species-specificityof this growth factor. Antman et al (1988) administered GM-CSF to patients with inoperable or metastatic sarcoma in whom bone marrow was free of disease. In these patients GM-CSF increased the bone marrow cellularity and myeloid: erythroid ratio and produced a peripheral neutrophilia with an eosinophilia. An increase in progenitor cell numbers in the peripheral blood was also observed, although this was not apparent in the marrow. GM-CSF is rarely detected in the peripheral blood (Cebon et al, 1988), although it was detected in a patient with a severe fungal infection (J. S. Cebon, unpublished data). It appears likely that GM-CSF is not required for day-to-day homeostasis, but may be important in responding to stress or inflammation. Phase I studies

Phase I studies have confirmed that GM-CSF administration by various routes results in leukocytosis which is predominantly comprised of neutrophils as well as eosinophils, and monocytes particularly at higher dose levels (Antman et al, 1988; Lieschke et al, 1990). Subcutaneous administration is more effective than the intravenous route. There is no effect on reticulocytes. Platelet effects are variable and small. The minimum platelet count occurs in the first 5 days of treatment in most patients, with the maximum count occurring in the second 5 days (Lieschke et al, 1990). Activation of monocytes has been observed by GM-CSF, with tumouricidal effects being observed in vitro (Grabstein et al, 1986). Only one partial response has been reported against a solid tumour in vivo (Steward et al, 1989). This was a heavily pretreated liposarcoma patient who had a more than 50% reduction in tumour volume after five cycles of GM-CSF. No other antitumour effects have been observed against solid tumours to date (Lieschke et al, 1990), although they have not been looked for exhaustively. Adverse effects

A 'first-dose' effect was recognized with intravenous GM-CSF (Lieschke et ai, 1989). Within 20 minutes of the first dose many patients developed symptoms of flushing, sweating , nausea, vomiting, back pain, involuntary leg spasms and dyspnoea, with hypotension, tachycardia and hypoxia being observed. The reaction was seen at highest frequency in patients with lung cancer and patients receiving short intravenous infusions. These responses

CLINICAL USES

763

were not seen with subsequent doses in the same course of GM-CSF but were seen at the start of following courses. Other toxicities observed at high doses in phase I studies include thromboses, pleural and pericardial effusions, inflammation and oedema. At lower doses other toxicities are reported: skin rashes, malaise, lethargy, anorexia, nausea, myalgia, arthralgia and fever. Pharmacokinetics

The clearance of exogenous GM·CSF and its biological activity appear to be influenced by its glycosylation, which differs depending on the type of cell system used to clone the molecule. Cebon et al (1990) demonstrated that highly glycosylated forms of GM·CSF found in the body have a lower affinity for GM·CSF receptor and a lower apparent biological activity than less heavily glycosylated forms, but may have longer in vivo survival (Donahue et al, 1986b) although the latter study investigated only the a half-life. Clinical aspects

Some clinical studies involving the use of GM-CSF in humans are listed in Table 3. Comparisons between studies are made difficult by the use of differently glycosylated forms of recombinant GM-CSF due to expression in different cell systems. There have been many studies carried out but what, if any, clinical benefit GM-CSF offers to patients receiving chemotherapy, particularly following chemotherapy, has not yet been defined . What is required is a large randomized placebo controlled trial using the usual four to six cycles of chemotherapy. Early studies in man were directed towards those conditions in which the disease state itself was causing marrow dysfunction, for example AIDS (Groopman et al, 1987), myelodysplastic syndromes (Vadhan-Raj et al, 1988a) and after bone marrow transplantation (Brandt et al, 1988). Owing to the nature of these conditions, however, it is difficult to be certain how much of the effects seen were due to GM-CSF or to the disease itself. Nevertheless, it did appear that GM-CSF may have a role in ameliorating the neutropenia characteristic of these conditions. Neutropenia related to chemotherapy. As shown in Table 3, all clinical studies using GM-CSF in the setting of myelotoxic chemotherapy have demonstrated that it shortens the duration of leukopenia. Some studies have shown clinical benefit, being fewer days with fever or on antibiotics (Herrmann et al, .199~), or being able to receive an earlier second dose of chemotherapy (Gianni et al, 1990). The latter study also noted fewer infections and a reduction in prophylactic platelet transfusions. Both of these studies examined only one cycle of therapy. however. and so it is difficult to extrapolate the results to a full course of treatment. Some studies have reported accelerated platelet recovery. but this is by no means a universal observation, and there is probably no significant benefit in terms of earlier platelet recovery to be obtained from the use of GM-CSF.

Clinical situation

Selected biological results

Shortened period of neutropenia GM-esF tolerated over whole course of chemotherapy Increase in neutrophils, eosinophils, monocytes Increase in platelets

N

N N

R

Myeloma, lymphomas, solid tumours Small cell lung cancer

Neutropenia not related to myelotoxic chemotherapy Severe congenital neutroN Elevated eosinophils not neutropenia (Kostmann's phils in most patients syndrome) Increase in WBC and ANC Chronic severe neutropenia N

Ovarian cancer

Shortened period of neutropenia Trend to high nadir levels of neutrophils Shortened period of neutropenia

N

ADMT

Sarcoma

No new bacterial infections Resolution of pre-existing infections Infections improved

Fewer febrile days Fewer days on antibiotics

Gianni et aI (1990)

Reduction in platelet transfusions Able to give chemotherapy earlier Reduction in infections No improvement in response rate

z Ganser et 81 (1989)

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Morstyn et al (l989a, 1990) de Vries et al (1991)

Herrmann et al (1988)

Antman et al (1988)

Herrmann et al (1990)

Steward et al (1990)

Logothetis et al (1990)

Reference

Improved response rate

Selected clinical benefits

Table 3. Selected clinical studies involving GM-esF.

Neutropenia related to myelotoxic chemotherapy N Shortened period of neutropenia Transitional cell urothelial cancer and MYAC Short nadir duration chemotherapy Shortened period of neutropenia N High-dose rrclophosShortened time to platelet phamide in breast cancer recovery Accelerated neutrophil and High-dose melphalan in N platelet recovery advanced colon cancer Shortened period of neutropenia Multiple solid and lymphoid N tumours treated with high dose chemotherapy +1-

Randomized

~

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N

N N N N

N

N N

Poor prognosis newlydiagnosed AML

AML Poor prognosis AML

Shortened aplastic period Shortened aplastic period

Improved neutrophil recovery, not platelets Recruitment of blasts into cell cycle

Increase in neutrophils and eosinophils Response maintained off therapy in 1/9 patients No response in 3/4 patients

Increase in neutrophils, eosinophils and monocytes

Muhm et aI (1989) Buechner et aI (1989)

Estey et al (1990) No benefit in remission rates, infections, neutrophil recovery, platelet recovery Low risk of promoting disease

Bettelheim et aI (1991)

Nissen et al (1988)

Antin et aI (1988) Champlin et al (1988) Vadhan-Raj et aI (1988b) Guinan et al (1990)

Gerhartz et al (1989)

83% CRrate

14127 patients with favourable responses

Estey et al (1991)

Increase in blast counts

N

N

Antin et al (1990)

No consistent benefit or adverse effects

Vadhan-Raj et al (1988a)

N

Increase in haematocrit with transfusion independence

Markusse et al (1990)

Increase in WCC

Elevated eosinophils Small rise in neutrophils

N

N

Acute myeloblastic leukaemia N De novo AML

Severe aplastic anaemia

Aplastic anaemia

Aplastic anaemia Aplastic anaemia

Mye10dysplastic syndromes Myelodysplastic syndromes and solid tumours Bone marrow fibrosis in myelodysplastic syndromes Refractory anaemia with excess of blasts (RAEB) or RAEB in transformation Myelodysplastic syndromes with low-dose Ara-C

Felty's syndrome

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Reduced bacterial infections Less time in isolation

Earlier neutrophil recovery

R

Techniques of administration Various malignancies comparing i.v, with s.c. administration Phase I study

HIV infection with GM-CSF +/- AZT

N

N

N

Subcutaneous infusion better than continuous i.v. better than short i.v. infusion

Groopman et al (1987)

Increases in WCC and ANC with AZTtherapy Increase in WCC, monocytes, and HIV p24 antigen

Lieschke et al (1989)

Lieschke et al (1990)

Pluda et aI (1990)

Vadhan-Raj et al (1990)

Link et al (1990)

Nemunaitis et al (1988)

Brandt et al (1988)

Klingemann et al (1990)

De Witte et aI (1990)

Powles et al (1990)

Reference

Increase in WBC and ANC

Hypoxialhypotension after first dose, particularly if high peak levels. Possibly related to intrapulmonary V/Q mismatch

Reduced hepatotoxicity and nephrotoxicity Fewer febrile days Fewer days in hospital

Earlier granulocyte recovery No effect on platelets Shortened period of neutropenia Earlier platelet recovery

N

N

Possible salvage of graft

Earlier neutrophil recovery

R

No increase in graft-versus-host disease No increase in leukaemic relapse No survival difference Decreased mortality Less bronchopneumonia Less antibiotic usage

Selected clinical benefits

N

Earlier neutrophil recovery

Selected biological results

Table 3. (cant.)

R

Other haematological conditions CLL and other lymphoN proliferative diseases HlV infection N

Bone marrow transplantation Allogeneic bone marrow transplantation for leukaemia (including myeloid leukaemias) Allogeneic bone marrow transplantation for leukaemia (including myeloid leukaemias) Graft failure after bone marrow transplantation Autologous bone marrow transplantation Autologous bone marrow transplantation for lymphoid malignancies Acute lymphoblastic leukaemia and NHL

Clinical situation

Randomized

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N

Impaired neutrophil skin chamber migration Preserved neutrophil function Increased neutrophil secondary granule release

Shorter aplastic period

R

N

N

Increase in circulating haemopoietic progenitor cells Increase in circulating haemopoietic progenitor cells enhanced by GM-CSF Increase in PBPC recovery with GM-CSF Earlier neutrophil recovery Earlier platelet recovery Faster platelet recovery

N

N

N

Bennett et al (1990)

Fewer days in hospital Less antibiotic usage Less use of other tests and invasive procedures Less cost with GM-CSF

Kaplan et al (1989) Devereux et al (1990)

Peters et al (1988)

Shea et al (1990)

Gianni et al (1989)

Siena et al (1989)

Villeval et al (1990)

Haas et al (1990)

Fewer platelet transfusions

Reduction in severity of mucositis

Can restore haemopoiesis

N, non-randomized; R, randomized; ANC, absolute neutrophil count; ARA-C, cytosine arabinoside; AML, acute myeloblastic leukaemia; AZT, zidovudine; CLL, chronic lymphocytic leukaemia; CR, complete response; MVAC, methotrexatervinblastine/doxorubicinlcisplatin; NHL, nonHodgkin's lymphoma; VfQ, ventilationlperfusion; WBC, white blood cells; WCC, white cell count.

Post autologous bone marrow transplantation Refractory carcinoma Various advanced malignancies

Neutrophil function

High dose carboplatin + GM-CSF +/- PBPe Relapsed Hodgkin's disease with ABMT, PBPC or both +/- GM-CSF

Autotransplantation using peripheral blood progenitor cells Various advanced malignancies (no ABMf) Various advanced malignancies with highdose cyclophosphamide (no bone marrow transplant) ABMT plus peripheral blood progenitor cells

Peripheral blood progenitor cellmobilization +/- autologous bone marrowtransplantation

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768

I. DAVIS AND G. MORSTYN

De Vries et al (1991) recently reported the results of a randomized double blind placebo controlled study of GM-CSF in 15 patients receiving chemotherapy with carboplatin and cyclophosphamide for ovarian cancer. Although this was a very small study it was the first to evaluate the effects of GM-CSF given over the whole course of chemotherapy as opposed to only one cycle. Only cycles in which full doses of cytotoxics were given were evaluated. They reported that GM-CSF increased total leukocyte counts at days 7, 10, and 15 at all dose levels of GM-CSF compared with the control group, and that neutrophils were elevated at all dose levels at days 7 and 10. At the highest dose level of GM -CSF (6 J,1.g kg -1 day"), both total leukocyte counts and neutrophil counts were elevated at day 22 also. Eosinophils contributed substantially to the total white cell count, and monocytes were also elevated. Local reactions were noticed in all patients on GM-CSF. No benefit could be observed for infections as only one was documented for the whole study group which seemed to have too few patients to demonstrate adequately the safety and benefit of GM-CSF administration over several cycles of chemotherapy. One may speculate that patient benefits would be difficult to demonstrate because the authors used conventional doses of well-tolerated chemotherapy. The clinical benefit of GM-CSF will not be identified until a large randomized study is published.

Neutropenia due to other causes. In situations where neutropenia is severe and chronic, or congenital (Kostmann's syndrome), GM-CSF has been able to elevate white cell levels in most patients, although in many patients the predominant increase was in eosinophils not neutrophils (Welte et al, 1990a). Treatment with GM-CSF in these patients has translated into a clinical benefit, with resolution of pre-existing infections in some patients and protection against new infections for the duration of therapy (Ganser et ai, 1989; Welte et al, 1990a). In Felty's syndrome, GM-CSF has been reported to induce an eosinophilia with a small rise in neutrophils, although the authors did not report whether there was an improvement in the risk of infection in this patient (Markusse et al, 1990). GM-CSF may also have a role in the treatment of drug induced neutropenia (Nand et al, 1990). Myelodysplastic syndromes. In many studies GM-CSF has been shown to increase granulocyte production in myelodysplasia (Vadhan-Raj et al, 1988a; Gerhartz et al, 1989; Nagler et al, 1990). The evidence is against GM-CSF causing clonal proliferation of blast cells in these disorders (Nagler et al, 1990), although rises in blast cells have been reported, particularly in patients having refractory anaemia with excess of blasts (RAEB) or RAEB in transformation (Estey et al, 1991). Other clinical benefits observed in some patients include an increase in haematocrit, with patients becoming independent of transfusions (Vadhan-Raj et al, 1988a). No decrease in marrow fibrosis has been seen consistently (Antin et al, 1990). It would appear from the available data, that GM-CSF may provide a benefit to some patients in terms of protection from infections and in transfusion requirements, but only while GM-CSF administration is maintained. There is no consistent elevation in platelet levels. When GM-CSF is ceased, the

CLINICAL USES

769

haematological parameters return to baseline. GM-CSF may therefore be most useful in these patients as a salvage treatment when they present with infections, but this has not been proven. Aplastic anaemia. In aplastic anaemia of mild to moderate severity, increases in neutrophils, eosinophils and monocytes are observed (Champlin et ai, 1988).In more severe cases no benefits are seen (Nissen et ai, 1988). Faisal et al (1990) found that GM-CSF increased lymphocyte numbers and induced lymphocyte activation in patients with aplastic anaemia. Guinan et al (1990) treated nine children with aplastic anaemia, eight of whom were refractory, with GM-CSF and observed an average fourfold increase in the neutrophil count in sixof them. One patient maintained a trilineage response offtherapy, but the other patients returned to baseline counts on cessation of therapy. Potter et al (1990) reported a sustained rise in neutrophils in a patient with very severe aplastic anaemia using GM-CSF and antilymphocyte globulin (ALG) in combination. This patient also became independent of platelet transfusions but still required red cell transfusions. It was felt that the initial rapid response in this patient may have been due to the GM-CSF, with the secondary sustained rise due to the ALG either alone or in combination. It would therefore appear that GM-CSF has only a short-term effect in these patients for the duration of treatment with the growth factor, and may be of most use in the treatment of infections in neutropenic patients. Acute myeloblastic leukaemia. One of the major problems in the therapy of acute myeloblastic leukaemia (AML) has been disappointing remission rates, and that remissions once obtained are often short-lived. The drugs used in AML are toxic, and many are cycle specific. GM-CSF has been used in the setting of AML in an attempt to recruit leukaemic cells into cell cycle and render them susceptible to cycle-specific cytotoxic drugs such as cytosine arabinoside (Ara-C), and also to reduce the duration and risks of chemotherapy induced aplasia. Estey et al (1990) reported no benefit with respect to remission rates, infection rates, neutrophil recovery or platelet recovery. Other workers have reported more rapid neutrophil recovery (Buechner et ai, 1989; Muhm et ai, 1989) and remission rates with short follow-up that are comparable with conventional therapy. Bettelheim et al (1991), using GM-CSF prior to chemotherapy in order to recruit blasts i~to cell cycle, and then restarting it at day 14in an attempt to enhance neutrophil recovery I reported an acceleration of myeloid recovery (22.5 cf. 25.2 days, P500/mm3) . Platelet recovery.was not enhanced. The complete response (CR) rate was 15/18(83:3% ),.wlth 12 patients achieving CR in the first cycle. The~e .were two early mfec~lve deaths and one patient did not achieve a remlssl~n. Follow up thus far IS o?ly 9 months, but nine patients remain in CR. Interestmgly, although the penpher~l.white cell count rose with the pretreatment phas~ of GM-CSF,. and.this included the leukaemic blasts, there was no mcr~ase m.relapse ra.tem this study with short-term follow-up. Longer follow-up times willbe reqUlre~ to confirm this observation. Cell cycle studies confirmed that blasts were being recruited into cell cycle.

770

I. DAVIS AND G. MORSlYN

The differences between these studies may represent patient selection or, more likely, reflect differences in the treatment regimen. For example, Estey et al (1990) did not give GM-CSF prior to cytotoxic therapy. Muhmet al (1989) began GM-CSF 3 days prior to chemotherapy. Bettelheim et al (1991) delayed the second treatment phase of GM-CSF until day 14, and perhaps further shortening of the neutropenic period with a reduction in infections would be possible by reintroducing GM-CSF at an earlier stage. This group also used previously untreated patients. Our group is currently involved in a pilot study looking at the use of GM-CSF in poor risk patients with AML (J. S. Wiley, unpublished observations), using a prechemotherapy treatment phase of GM-CSF and recommencing GM-CSF on the day following the completion of chemotherapy. It may be that using GM-CSF in previously untreated patients will give better results. PBPC +/- bone marrow transplantation. During phase I studies it was noticed that GM-CSF administration increases circulating haemopoietic progenitor cells in the peripheral blood (Siena etal, 1989;Villevalet al, 1990), and that all measurable progenitor cells may be increased. These cells are capable of restoring haemopoiesis after high-dose chemotherapy (Haas et aI, 1990),and lead to early platelet, as wellas myeloid, engraftment (Nemunaitis et al, 1988;Gianni et al, 1989).Sheaet al (1990)used high-dose carboplatin in patients with a variety ofsolid tumours and then administered either GM-CSF alone or GM-CSF with PBPC support. The PBPC were collected after GM-CSF stimulation. They noted a reduction in the time to neutrophil recovery with PBPC (not significant), but a significant improvement in platelet recovery and a reduction in platelet transfusion requirements. In the setting of high-dose chemotherapy with autologous bone marrow transplantation (ABMT) for lymphoid malignancies, post-transplant GM-CSF leads to a reduced period of neutropenia, with an apparent direct patient benefit of a reduction in the number of febrile days and time in hospital (Nemunaitis et aI, 1988). Overall the reduction in the duration of neutropenia has been of the order of 2-3 days, and strategems to reduce this further should lead to much greater benefits. When ABMT is combined with PBPC stimulated by GM-CSF, engraftment is more rapid and platelet recovery is also significantly accelerated (Gianni et al, 1989). Bennett et al (1990), using GM-CSF in patients receiving high-dose chemotherapy and ABMT and/or PBPC reconstitution, reported direct patient benefits from the use of GM-CSF in the form of small reductions in days in hospital, antibiotic use and the use of other invasive tests and procedures. They also calculated a cost benefit for the GM-CSF group, although it was not clear whether the cost of GM-CSF itself was included. Link et al (1990) found that GM-CSF shortened neutrophil recovery time, reduced bacterial infections, and reduced the time in isolation for patients receiving ABMT for acute lymphoblastic lymphoma or non-Hodgkin's lymphoma. It would appear, therefore, that PBPC can improve the results of engraftment when used alone or with ABMT. The method of stimulating PBPC may be important. The objective is to obtain as many progenitor cells as possible from the peripheral blood, and

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771

the optimal conditions for achieving this are not yet determined. It is probably important to have minimally pretreated patients who are more likely to have good marrow reserve. Some of these studies incorporated cyclophosphamide, which is known also to stimulate PBPC mobilization (To et al, 1990) and to have a relatively sparing cytotoxic effect on stem cells (Smith et al, 1983), prior to GM-CSF. Under these conditions, the yield of PBPC is significantly higher and recovery from the cyclophosphamide induced cytopenia occurs earlier (Ravagnani et al, 1990). Allogeneic bone marrow transplantation is another field in which GM-CSF has been investigated. In a randomized double blind trial, Powles et al (1990) administered human recombinant GM-CSF or placebo to patients undergoing allogeneic bone marrow transplantation for leukaemia, some of whom had myeloblastic leukaemia. They found that the median neutrophil count at 14 days was significantly higher in the treated group than in the placebo group (1.90 x 109/litre versus 0.46 x 109I1itre), but that the time to recovery of neutrophils to >0.5 x 1091litre was not significantly shorter. This may be due to both a small effect and small patient numbers. There was no increase in graft-versus-host disease with treatment, although the group receiving GM-CSF had a higher lymphocyte count between days 10 and 15. Most importantly, there was no evidence that treatment with GM-CSF increased the risk of leukaemic relapse, although the longest follow-up in this study was 18 months and there were few patients who survived beyond 5 months. Overall survival was the same between the groups but there was a substantial early mortality (30% 5-month survival) in both arms of the trial which makes this difficult to interpret. The high mortality may have been due to the fact that many patients were not transplanted in remission. Another group (De Witte et ai, 1990) used GM-CSF in patients receiving allogeneic T-cell depleted marrow, some of whom also had myeloid leukaemia. Neutrophil recovery was shortened and mortality due to infections or other transplant-related causes may also have been reduced by GM-CSF, although this did not reach statistical significance. The incidence of bronchopneumonia and the use of antibiotics was reduced in the GM-CSF group. Ofgreat potential interest is th~ observation that GM-CSF ~ay be of use in salvaging those unfortunate patients who develop graft failure after allogeneic bone marrow transplantation (Klingemann et aI, 1990). Previously the only hope for these patients was another allogeneic transplant, usually with very poor results. It may be that GM-CSF will find a niche in the treatment of these patients.

Human immunodeficiency virus type 1 (HIV·I) infection. Patients with HIV·1 infection, in addition to the many problems attributable to T-cell dys!unction., also h.ave other haematological disorders, some of which may be ratrogemc. Vanous cytopenias may occur with HIV-1 infection per se and thes~ may all b~ exa~erbated by drugs such as AZT. Another majo; problem 10 these patients IS cytomegalovirus retinitis, which often results in blindness. !he ~reat~ent of this condition requires the use of the antiviral agent ganciclovir, which also may cause myelosuppression. In a patient who

772

I. DAVIS AND G. MORSlYN

already has depressed haematological cell counts, the dose of ganciclovir may need to be reduced, with a corresponding loss of efficacy. Measures which can overcome these problems of myelosuppression are urgently needed. In a phase I trial, GM-CSF given to patients with AIDS produced an increase in peripheral neutrophils and eosinophils and a slight rise in monocytes (Groopman et al, 1987). Neutrophil function may also have been improved (Baldwin et aI, 1988). GM-CSF has been observed to potentiate HIV-1 replication while at the same time enhancing the effect of AZT in vitro (Perno et al, 1989). Pluda et al (1990) alternated GM-CSF with AZT and noted an increase in total white blood cell count and stimulation of monocyte function. The HIV-1 p24 antigen level in serum was also increased during GM-CSF treatment, but fell to lower levels in subsequent treatment cycles. Haematological toxicity was less than with AZT therapy. Sulecki et al (1991) reported the use of GM-CSF in the treatment of ganciclovirinduced neutropenia. Their patient had undergone a matched unrelated allogeneic bone marrow transplant for myeloid leukaemia and developed cytomegalovirus pneumonitis. Ganciclovir had to be withdrawn due to neutropenia. Following GM-CSF, the neutrophil count recovered and the patient received a full course of ganciclovir with resolution of his pneumonitis. These observations are being pursued. Groopman (1990) has recently reviewed the role of GM-CSF in HIV-1 infection.

ERYTHROPOIETIN Clinical studies involving erythropoietin (EPO) are summarized in Table 4. EPO has been used in the setting of end-stage renal failure on dialysis, with benefits in the form of elevation of haemoglobin with reduction in anaemia symptoms and a decrease in transfusion requirements (Winearls et al, 1986; Eschbach et aI, 1987). EPO would appear to have a useful role in the treatment of these patients who have little or no endogenous EPO. The situation is not as clear in other conditions where endogenous EPO may be normal or elevated. The response of endogenous EPO to anaemia may be blunted in patients with cancer, and chemotherapy (particularly with cisplatin) may further suppress it, although these patients usually maintain normal responsiveness to other stimuli such as hypoxia (Miller et aI, 1990a). Studies of patients with multiple myeloma and other types of malignant bone marrow infiltration have been performed (Ludwig et aI, 1990; Oster et al, 1990). Despite the presence of high circulating levels of endogenous EPO and poor bone marrow reserve, both of these studies demonstrated that erythropoiesis could be stimulated by additional exogenous EPO,leading to a lessening in the severity of symptoms and a decrease in transfusion requirements. Rises have often been small, however, and thrombotic complications such as thrombosis of Hickmann's catheters have been reported (Miller et ai, 1990b). It is not likely that EPO will find a niche in the routine treatment of these patients.

R

Chronic renal failure on haemodialysis

Means et al (1989)

Increased yield of units Higher haematocrit in treated patients at end of trial Improvement in chronic anaemia

N

N

Autologous transfusion

Rheumatoid arthritis

N, non-randomized; R, randomized.

Goodnough et al (1989)

Fall in transfusion requirements

Improvement in anaemia caused byAZT

N

Levine et al (1989)

Oster et al (1990)

Fall in transfusion requirements

AIDS

Ludwig et al (1990)

Improvement in symptoms

Rise in haemoglobin despite high endogenous EPO

N

Bone marrow infiltration by , malignancy

Winearls et al (1986)

Fall in transfusion requirements Hypertensive encephalopathy Fistula thrombosis

Increased erythropoiesis

Eschbach et al (1987)

Fall in transfusion requirements

Increases in: haematocrit, ferrokinetics, blood pressure, creatinine, potassium Increase in reticulocytes, haemoglobin

Miller (199Oa)

N

Reference

Clinical benefits

Biological results

Low endogenous EPO levels Further suppression by chemotherapy Adequate response to hypoxia No exogenous EPO given

N

Multiple myeloma

Various solid tumours

N

Randomized

Clinical situation

Table 4. Selected clinical studies involving erythropoietin.

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774

I. DAVIS AND G. MORSTYN

Other conditions for which EPO has been used include HIV-l infection. Levine et al (1989) reported an improvement in the anaemia caused by AZT therapy, with a reduction in transfusion requirements. Patients with rheumatoid arthritis and chronic anaemia may also benefit (Means et al, 1989). Potential future uses for EPO may be in the collection of autologous blood prior to operation (Goodnough et ai, 1989), thereby eliminating the currently prevailing risks of blood-borne infections and of cross-matching. Specific groups, such as Jehovah's Witnesses, may also be suitable for treatment with EPO under certain circumstances. Riggs et al (1990) have used preoperative EPO in a Jehovah's Witness undergoing cardiac surgery who was anaemic at presentation, with good results. Thompson et al (1991) report the use of EPO in a patient with multiple red cell alloantibodies and anaemia of chronic disease requiring elective surgery. The haematocrit increased with the use of EPO despite serial blood donations. Other conditions causing chronic anaemia, for example sickle cell disease, may also be possible candidates for the use of EPO. EPO therapy has been well tolerated. In the setting of chronic renal failure adverse events related to prolonged dialysis time and hypertension, and fistulae thromboses have also been reported (Winearls et al, 1986; Eschbach et ai, 1987). Another possible concern regarding the use of recombinant EPO is that it is produced by mammalian cells and is very difficult to distinguish from the endogenous form. As such it could be used illicitly, for example, by athletes to increase red cell mass and oxygen carrying capacity. This would be very difficult to detect. It would also be very dangerous, as the risks of hyperviscosity would be significant in those people whose red cell mass is not low before treatment.

OTHER GROWTH FACTORS M-CSF M-CSF (CSF-1) is a relatively specific monocyte-macrophage growth factor originally isolated from human urine (Das et ai, 1981) and recombinant human M-CSF was first produced by Kawasaki et al (1985) in monkey cells. There appear to be several different cDNA clones, all with similar biological activity. M-CSF causes differentiation of bone marrow cells into monocytemacrophage colonies (Metcalf and Burgess, 1982), and increases monocyte production of interferon and tumour necrosis factor (Warren and Ralph, 1986), while enhancing specific tumouricidal antibody dependent cell mediated cytotoxicity (Mufson and Ahgajanian, 1987). One very interesting report (Nemunaitis et ai, 1990) involved the use of M-CSF in patients with invasive fungal disease. Most patients had reduction or resolution of their infections, including two with refractory hepatic candidiasis who had complete biopsy proven resolution. Those patients who received M-CSF after bone marrow transplantation showed no evidence of increasing severity of pre-existing graft-versus-host disease. There may be a

CLINICAL USES

775

use for M-CSF in the setting of immunosuppressed patients or those with severe fungal infections. Masaoka et al (1990) have reported a randomized double blind trial of human M-CSF in allogeneic and syngeneic bone marrow transplants for leukaemia. Granulocytes returned earlier in the M-CSF group, although the benefit was only 2-3 days. There was no increase in graft-versus-host disease or of leukaemic relapse, including monocytic leukaemias. Late follow-up showed no difference between the two groups with respect to graft failure. IL-2

IL·2 is a potent T-cell growth factor, synthesized by antigen-specific T cells and recognized by a specific receptor, the IL-2R or TAC antigen. There is probably another 75 kDa receptor which is involved in IL-2 binding to cells which do not constitutively express TAC (Tsudo et al, 1987). In phase 1 studies (Rosenberg et al, 1985), a minority of patients achieved tumour regression using IL-2 alone or IL-2 in combination with lymphocytes activated in vitro with IL-2 (lymphokine activated killer or LAK cells). Toxicity was severe and often life-threatening, particularly with a capillary leak syndrome at high doses, with hypotension, oedema and pulmonary oedema. Only a minority of patients had useful clinical remissions. Using IL-2 at lower doses and with different regimens of administration may help to reduce this toxicity. IL-2 has been used in clinical trials to induce LAK cells. The predominant conditions for which IL-2, with or without LAK, has been used are renal cell carcinoma and malignant melanoma, and the results of these have been recently reviewed (Borden and Sondel, 1990). Generally, overall response rates are of the order of 20-30% and most of these are partial responses which may have little clinical relevance, particularly as the treatment itself is toxic. Another interesting approach is the use of IL-2 to induce activation and proliferation of autologous tumour-infiltrating lymphocytes (TIL) as a form of adoptive cellular immunotherapy. Belldegrun et al (1988) described significant anti tumour activity from TIL treated with IL-2 against renal carcinoma cells in vitro. Clinical trials pursuing this question are currently underway (Custer and Lotze, 1990). Other possibilities include the use of IL-2 in combination with other biologicals such as interferon, IL-4 or IL-113 to take advantage of the ability of these agents to modify antigen presentation and the immune response in a fashion which may be complementary to IL-2. Monoclonal antibodies against tumours may also enhance the antitumour activity of IL-2 (Foon, 1989). It is also possible that IL·2 may be used to augment the 'graft-versusleukaemia' effect that has been observed following allogeneic bone marrow transplantation. IL-l

IL-t has recently been reviewed (Platanias and Vogelzang, 1990). Phase I

776

I. DAVIS AND G. MORSTYN

studies have revealed side-effects including fever. chills. headaches. hypotension, nausea. vomiting, myalgia, arthralgia and local reactions (Smith et al, 1990). Possible uses of IlA include combinations with GM-CSF. or with Il-2/LAK combinations. Other possibilities include utilizing antagonists to the Il-l receptor (see Chapter 9). which in animal studies has demonstrated protection against infections and has also inhibited proliferation of myeloid leukaemic cells in vitro (see Dinarello, 1991, for extensive review of 1L-1). IL-3 Interleukin-J (ll-3, Mulli-CSF, CSF-2a, CSF-2b. haematopoietin 2, mast cell growth factor) is a multipotential growth factor with activities which overlap and synergize with GM-CSF, although 1L-3appears to act on more immature progenitor cells. Preclinical studies in animals have shown that Il-3 in combination with GM-CSF can increase the numbers of PBPe (Geissler et al, 1989), and improve the grafting efficiency of bone marrow (Tavassoli et al, 1989). Alter et al (1990) found that in vivo administration of Il-3 to humans increased PBPe recovery, and bone marrow stem cell colony size and number. 1L-3 has been used in combination with GM-CSF. In a phase II study in myelodysplastic patients, Dunbar et al (l990a) administered first GM-CSF and then Il·3 after an 8-week break. They found that IL-3 had comparable activity to GM-CSF in terms of increasing neutrophils, and may lack a depressant effect on platelet counts which they observed with GM-CSF. The same group (Dunbar et al, 1990b) used 1L-3 in patients with DiamondBlackfan anaemia in combination with GM-CSF in a similar fashion. Both factors improved erythropoiesis. although 1L-3 appeared to be superior in this study with small numbers of patients. Toxicity due to Il-3 included fever, nausea and fatigue. none of which required dose reduction. Ganser et al (l990a) compared sequential Il-3 and GM-CSF with Il-3 alone in patients with various neoplasms. The combination was more effective in stimulating haemopoiesis and allowed a shorter treatment course to be given while maintaining a beneficial effect on thrombopoiesis which was attributable to 1L-3. Gillio et al (1990). in a phase I trial of patients with myelodysplastic syndrome or aplastic anaemia. found variable responses, but a number of patients achieved rises in leukocytes and platelets, with one striking platelet response. Toxicity was mild and whole blood histamine levels were not elevated. Ganser et al (l990b) used 1L-3in patients with myelodysplastic syndromes and found increases in all lineages. although erythroid responses were less pronounced. Two of four severely thrombocytopenic patients improved to the point where platelet transfusions could be discontinued. Patients with 5q-syndrome had transient worsening of erythropoiesis. The same investigators (Ganser et al, 199Oc) studied patients with cancer and normal haemopoiesis, and patients with marrow failure. and again reported improvements in all cell lines. Side-effects in both studies were minor. Another possible use for 1L-3 may be in the setting of recovery of bone

777

CLINICAL USES

marrow post chemotherapy, although as yet there is little information regarding this. Concerns regarding the use of IL-3 relate to the possible stimulationof leukaemic blasts, and side-effects related to mast cell stimulation, althoughthe latter hasnot been observedin the clinical trialsto date. Ano~her concern is that IL-3 may stimulate clonal growth of other malignanCl~s, such a~ small cell ~ung cancer (Pedrazzoli et al, 1990), These questions are beingpursued In further studies. IrA

IL-4has undergonephase I studyand isenteringphase II studies. There are interestingpreclinical data to suggest that it may have an anticancerrole or playa part in long-lasting tumourimmunity (Tepper et al, 1989; Bosco et al, 1990). Davis et al (1991) reported, from a phase I study of subcutaneous recombinant humanIL-4,onecompleteresponseina patientwithrefractory Hodgkin'sdiseaseafter failing high-dose chemotherapyand autologous bone marrowtransplantation,and a partialresponseinone patientwithlowgrade non-Hodgkin's lymphoma. The predominant adverse effects reported included fever, headache, fluid retention, localreactionsand an elevationin serumalkalinephosphatase. PhaseI[ trialsofa combination of IL-2and [L-4 usingTILare underway (Custerand Lotze,1990). Invitroexperiments using lymphocytes frompatientswhohavereceived IL-2 demonstratethat IL-4 can enhance IL-2 induced or antibody induced lymphocyte proliferation. suggesting a possible rolefor IL-4in increasingTIL proliferationor LAKcell production ex vivo (Trcisman et al, 1990). Other areas of possible clinical application includeatopy, autoimmune disordersor inflammatory disorders. IL-4 appears to play an important role in these conditions. GROWTH FACTORS WITH I'OTENTIAL

CLl~ICAL

USE

Interleukin-6 (IL-6) is a pleiotropiccytokine which is Involved in immune regulation.acute phase reactions,haernopoiesis, and probablyhostdefence mechanisms. It has previously been called J3rinterferon, D-cellstimulatory factor 2, and hybridomaJplasmacytoma growth (actor, amongst other synonyms. It has been extensively investigated in vitro but has not yet entered clinical trials. Areas of interest includeD-ccll malignancies such as multiplemyeloma, sinceIL-6has been foundto be a necessary growthfactor in some cases and may be an autocrine or paracrine prollferative stimulus (Kawa~o et al, 1988): Possi~le c~inical applications involve interferingwith the actions of IL-6 with antibodies or antagonists. Stem cell factor (SCF) is a recentlydescribedgrowthfactor which acts on early haemopoietic progenitorcellsto enhance their proliferation(Zsebo et al, 1990), particularlyin the presence of other growth factors such as lL-6, IL·IJ3.1L-3 and G-CSF. Interleukin-9 (IL-9) was purified from a murine T-cell line and subsequent,ly mapped to hum,an chromosome5 (Mock et al, 1990). It supports erythroid colony formation (Donahue et al, 1990). A human eDNA

778

I. DAVIS AND G. MORSTYN

encoding the human homologue was isolated from a megakaryoblastic leukaemic cell line (Renauld et al, 1990). Transfection studies indicate that IL-9 may be involved in the development of certain T-cell tumours (Uyttenhove et ai, 1991). It is possible that intervention in these multiple activities may be of use in the areas of bone marrow transplantation, or in direct anticancer effects. Interleukin-Ll (IL-ll) is derived from a primate bone marrow derived stromal cell line, which has activities including the stimulation of an IL-6 dependent murine plasmacytoma line, and synergism with IL-3 in supporting murine megakaryocyte colony formation (Paul et ai, 1990). It may interact with IL-6 in the control of various tumours , or may have clinical significance in supporting megakaryocyte recovery following chemotherapy in combination with other factors. CONCLUSIONS The haemopoietic growth factors are providing new insights into the mechanisms of haemopoiesis and developmental differentiation. Many of these properties lend themselves to manipulation in various clinical situations. Erythropoietin and G-CSF have found important niches in different clinical situations and the main areas of interest at present lie in the amelioration of the consequences of anticancer therapy, in which they will play important roles. The role of GM·CSF is not yet clear; its greater toxicity makes it less attractive as an agent for the treatment of neutropenia or neutropenic sepsis , but its different biological activities suggest other potentially useful roles. Many other cytokines and growth factors are currently under investigation or will shortly enter clinical trials. It may be expected that further improvement in the morbidity of cancer therapy will ensue, as well as in other clinical situations. If chemotherapy induced cytopenia, particularly neutropenia, can be abrogated as a toxicity of treatment, then the possibility exists that new combinations of cytotoxic drugs, or of dose intensification of existing combinations, may result in improved response rates. There is some evidence in favour of the concept of increasing dose intensity of cancer chemotherapeutic agents to improve tumour responses (Bronchud et ai, 1989; Dodwell et ai, 1990). Other non-malignant conditions also appear to be amenable to therapy with the haemopoietic growth factors. Of increasing importance will be the role of these factors in the treatment of other conditions such as AIDS. As the biology of newer cytokines and growth factors is elucidated, many more clinical applications and benefits may be expected to become apparent. SUMMARY The haemopoietic growth factors are a diverse group of hormones with effects on different haemopoietic cell lineages and at various points in their developmental differentiation. The biology of many of these factors is now

CLINICAL USES

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well understood. They have entered clinical trials and have demonstrated benefits in particular clinical situations. The thrust of current phase II and III clinical investigations now is to use these factors, alone or in combinations, to modify various disease states and to ameliorate many of the side-effects of other therapeutic agents, particularly cytotoxic anticancer agents. Many other disease states also lend themselves to therapy with these growth factors. Other haemopoietic growth factors have not been as extensively studied in humans but hold great promise. In this chapter, the current status of the haemopoietic growth factors presently under clinical trial has been reviewed. In addition, several factors which have been recently described but which have not yet entered clinical trials have been discussed.

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Bronchud MH, Howell A, Crowther D et al (1989) The use of granulocyte colony-stimulating factor to increase the intensity of treatment with doxorubicin in patients with advanced breast and ovarian cancer. British Journal of Cancer 60: 121-125 . Buechner T , H iddemann W, Koen igsmann M et al (1989) Hematologic and therapeutic effects of recombinant human GM-CSF following chemotherapy (0) in patients with acute leukemias at higher age or after relapse. Blood 74 (supplement 1): 271a (abstract). Cebon JS & Morstyn G (1990) The potential role of granulocyte-macrophage colony stimulating factor (GM-CSF) in cancer chemotherapy. Cancer Surveys 9: 131-155 . Cebon J, Dempsey P, Fox R et al (1988) Pharmacokinetics of human granulocyte-macrophage colony-stimulating factor using a sensitive immunoassay. Blood 72: 1340-1347. Cebon J, Nicola N, Ward M et al (1990) Granulocyte-macrophage colony stimulating factor from human lymphocytes. The effect of glycosylation on receptor bind ing and biological activity. Journalof Biological Chemistry 265: 4483-4491. Champlin RE, Nimer SD, Ireland P, Delle DH & Golde DW (1988) Treatment of refractory aplastic anemia with recombinant human granulocyte-macrophage-

Clinical uses of growth factors.

The haemopoietic growth factors are a diverse group of hormones with effects on different haemopoietic cell lineages and at various points in their de...
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