Inr J Rudrurron Oncwlog~ Bd PhyJ Vol. Pnnted I” the U.S.A. All nghts reserved
22. pp.
72 1-725 Copynghi
0 Session E: Bioreductive PHASE
I STUDY PATIENTS
0360-3016/92 $5.00 + .Xl 0 1992 Pergamon Press plc
Therapies
OF BW12C IN COMBINATION WITH MITOMYCIN WITH ADVANCED GASTROINTESTINAL CANCER
C IN
J. R. S. RAMSAY, M.Sc., MRCP, FRCR,’ N. M. BLEEHEN, FRCP, FRCR, FACR(HON),’ I. DENNIS, B.Sc.,’ P. WORKMAN, PH.D.,’ R. WARD, B.Sc.,’ S. J. FALK, MRCP, FRCR,’ P. BEDFORD,
PH.D.,~
R. WOOTTON,
PH.D.~
AND A. B. W. NETHERSELL,
MRCP,
FRCR2
‘Medical Research Council Unit and University Department of Clinical Oncology and Radiotherapeutics, Hills Road, Cambridge CB2 2QH; ‘The Wellcome Research Laboratories, Langley Court, Beckenham, Kent BR3 3BS, UK. drug BW l2C with mitomycinC was investigatedin a Phase I study of 18 patients with advancedgastrointestinalcancer. The dose of BW12C was increased from 20 mg/kg to
The effect of combining the oxyhemoglobin-modifying
50 mg/kg to modify the hemoglobin-oxygen saturation curve by up to 48%. The period of maximum modification was then prolonged for up to 3 hr by a maintenance infusion of 4-6 mg/kg/hr. Pharmacokinetics of BW12C and mitomycin C were performed in all patients. Peak levels of BWl2C increased from 139 pg/ml to 378 pg/ml. Plasma half life was independent of dose, with an average of 3.3 hr. BW 12C was well tolerated with no severe side effects. Three patients had objective tumour responses. Mitomycin C, BWl2C, Hypoxia, Gastrointestinalcancer.
INTRODUCTION
METHODS
BW 12C (5-[2-formyl-3-hydroxyphenoxy] pentanoic acid*) is a substituted benzaldehyde designed to bind preferentially to oxyhemoglobin, stabilizing the molecule in a form that has a high affinity for oxygen. This process leads to a left shift in the oxygen saturation curve (OSC), thereby reducing the release of oxygen to the tissues (2,4). Animal studies have shown that it can increase tumor hypoxia and potentiates the antitumor activity of some bioreductive drugs ( 1, 3). The cytotoxic agent mitomycin C (MMC) has been used as a single agent or in combinations in the treatment of advanced gastrointestinal cancer (8). It is metabolized under reducing conditions to form a bifunctional alkylating agent which cross-links, and inhibits the synthesis of DNA. In studies with a variety of neoplastic cells, the drug was found to be more cytotoxic to hypoxic than to aerobic cells (7). It is thus hoped that the combination of MMC with BW 12C will result in greater efficacy. The purpose of this study is to monitor the safety of increasing doses of BW 12C in combination with MMC in patients with gastrointestinal cancer who have failed standard therapy. In association with this, we have measured the changes in the OSC caused by BW 12C and the pharmacokinetics of MMC and BW 12C.
AND MATERIALS
Patient selection Eighteen patients (age 36-69) with progressive metastatic gastrointestinal cancer have been entered into the study. Primary disease was colorectal adenocarcinoma in 17 patients and adenocarcinoma of stomach in 1 patient. Seventeen patients had previous surgery, seven previous radiotherapy and seven previous chemotherapy with 5fluorouracil. All patients had WHO status I 2, hemoglobin 2 lOg/lOO ml, white cell count L 4 X 109/L, and platelets 2 100 X 109/L. There was no history of ischaemic heart disease or cerebrovascular disease, and all patients gave written informed consent. Pre-trial patients underwent full clinical examination with radiological assessment of disease extent. On the day of treatment patients were closely monitored for toxicity and any adverse effects recorded. Patients were subsequently assessed I and 4 weeks after treatment. Patients not showing progressive disease or clinical deterioration proceeded to a second course of treatment after 6 weeks.
Drug administration Cohorts of two patients were treated with a 1 hr infusion of BW 12C, commencing at a dose of 20 mg/kg. The dose was escalated in the first four cohorts up to 40 mg/kg.
Presented at the Seventh International Conference on Chemical Modifiers of Cancer Treatment, Clearwater, FL, 2-5 February 1991.
Reprint requests to: Professor N. M. Bleehen. Accepted for publication 26 July 199 1. * Wellcome Ltd., UK. 721
I.
J. Radiation
Oncology
0 Biology 0 Physics
Volume
22, Number
4, 1992
50
20
0
0
10
0 0
60
120 minutes
120
180 240 minutes
160
1 40
Dose Fig. 1. Percent of hemoglobin of BW12C in 18 patients.
BW12C modification
mglkg
mglkg at escalating
dose
The next three cohorts received a loading infusion of 40 mg/kg followed by a maintenance infusion of 6 mg/kg/ hr increased from 1 to 3 hr to prolong the maximum modification of the OSC. The final two cohorts were treated with 45 and 50 mg/kg loading infusion with a maintenance infusion of 4 mg/kg/h over 3 hr. MMC was administered as an intravenous bolus at a dose of 20 mg/m2 immediately at the end of the BW 12C infusion.
Modijcution of’haemoglobin-oxygen saturution curve Blood samples were collected at 0, 30, and 60 min during the loading infusion, hourly during the maintenance infusion, and 30, 60, and 120 min thereafter. Samples were kept on ice and transported within 24 hr to the Wellcome Research Laboratories for analysis. The whole blood oxygen saturation curve was measured by a spectrophotometric technique. Each post-BW 12C infusion curve was analyzed by comparison with a series of artificially constructed curves calculated from the equation of Beddell et al. (2). The proportion of BW 12C reacted hemoglobin (percentage modification) was determined from the artificial curve that corresponded to the observed post-infusion curve.
0
60
40
mglkg
300
360
, maintenance
at
Gmglkglh
Fig. 2. Percent of hemoglobin modified in pairs of typical patients on 40 mg/kg infusion over 1 hr (a) or with additional maintenance at 6 mg/kg/hr for subsequent 3 hr (b).
Blood sample analysis BW 12C was extracted from whole blood by addition of water to form a hemolysate, followed by acidification
BWl2C
Table 1. Pharmacokinetics
with mitomycin
C 0 .I. R. S. RAMSAY
of BW12C in haemolysate
Dose mg kg-’
Maintenance h
No. of courses
Peak cone pg ml-’
20
-
3
158 (109-187) 270 (227-3 13) 348 (285-434) 335 (3 15-348) 287 (25&334) 272 (252-29 1) 378 (308-448) 355 (275434) 334 (323-344)
30
3
35
4
40
-
3
40
1
3
40
2
2
40
3
3
45
3
3
50
3
2
with hydrochloric acid, and then protein precipitation with acetonitrile. MMC was extracted from plasma using Waters? C 18 Sep-paks. BW 12C and MMC drug concentrations were assayed by reverse phase HPLC, with U.V. detection at 280 nm for BW 12C and 365 nm for MMC. Separations were achieved on a Waters Nova-Pak (4 pm) Rad-Pak column. Each drug was eluted using an appropriate gradient of methanol/sodium phosphate buffer.
RESULTS
Mocljication qf haemoglobin-oxygen
saturation curves
There was a dose-related increase in percentage modification with increasing dose of BW 12C from 20 to 50 mg/kg (Fig. 1). The maximum modification obtained at the end of the infusion was 42%. In one patient treated at 45 mg/kg a modification of only 18% was obtained which was associated with a low BW 12C peak plasma level of 270 pg/ml. For patients treated with a loading infusion only, the maximum modification occurred at the end of the infusion or 30 min after completion (Fig. 2a). Patients receiving a maintenance infusion of 6 mg/ kg/hr had the period of modification prolonged for over 4 hr. There was, however, a slow increase in the degree of modification during the maintenance infusion in some patients (Fig. 2b). For this reason the dose was reduced to 4 mg/kg/h for the final four patients. This has given a more stable maximum degree of modification during the infusion.
t Waters division
of Millipore,
Milford,
MA, U.S.A.
723
et (I/.
(26 courses in 18 patients) tu2
h 1.93 (1.73-2.15) 3.39 (2.624.78) 3.29 (2.80-3.57) 3.90 (2.984.55) 2.96 (2.38-3.88) 3.61 (2.904.32) 2.83 (2.77-2.88) 3.56 (2.60-4.53) 4.08 (3.794.36)
AUC,.,
pg ml-’ h 570 (360-760) 1480 (1280-1810) 1840
(1550-2290) 2570 ( 1960-2970) 1610 (1270-2170) 1990 ( 1540-2450) 2550 (2020-3080) 2786 (1620-3952) 2686 (2570-2800)
Pharmacokinetics BW 12C haemolysate pharmacokinetics are summarized in Table 1. Peak levels increased with dose from a mean of around 139 pg/ml at 20 mg/kg to 378 pg/ml at 40 mg/ kg. The AU&,. increased with dose. The elimination half-life was independent of dose at around 3.3 hr. Repeat pharmacokinetics within patients were very reproducible (not shown). The plasma pharmacokinetics of MMC were as expected. The mean concentration at 15 min post-injection was 0.96 pg/ml (range 0.71-1.31 pg/ml). Values of tliza and t,,$ were 0.24 h (0.054-0.96 h) and 1.15 h (0.433.02 h), respectively. The mean AUCo_& value was 1.07 pg/ml h (0.77-I .42 pg/ml h). Haemolysate BW 12C and plasma MMC pharmacokinetics for a patient receiving a dose of 40 mg/kg of BW 12C with a 3-hr maintenance infusion are illustrated in Figure 3. In three patients for whom it was possible to obtain plasma samples for MMC with and without BW 12C, the kinetic parameters were closely similar.
Toxicity Adverse effects of BW 12C were only seen on the day of treatment with no prolonged or delayed effects. Six patients had some pain or erythema around the injection site. This was usually mild and only in one patient was the infusion temporarily stopped with relief of his symptoms. The effect was seen most frequently with patients receiving the higher doses and was related to the concen-
724
1. J. Radiation Oncology 0 Biology 0 Physics
0 -4
-2
0
2
Time (h) from end of infusion Fig. 3. Pharmacokinetics of a typical patient. Concentration of BW 12C (0) in hemolysate and MMC (A) in plasma following 40 mg/kg infusion over 1 hr with maintenance of BW 12C 6 mg/ kg/hr over subsequent 3 hr. MMC was given at end of maintenance infusion of BW 12C.
of drug in the loading infusion. Other side effects recorded were headache (one patient), nausea and vomiting (one patient), sinus tachycardia (one patient) and syncope (one patient). The latter occurred in a patient receiving 35 mg/kg and was not observed when a second dose was administered. MMC toxicity was limited to myelosuppression with a maximum WHO grade 2 Hb toxicity (two patients), grade 2 neutropaenia (one patient) and grade 3 platelet toxicity (one patient). There were no cases of sepsis, bleeding, or treatment-related deaths. tration
C’linicul response Patients were assessed for clinical response after 4 to 6 weeks. Those demonstrating obvious progressive disease or clinical deterioration were removed from the study. Eight patients with stable or responding disease proceeded with a second course of treatment giving the same doses and with repeat pharmacokinetics. One patient had a complete response after two cycles (anastomotic recurrence), one patient a partial response after two cycles (liver), one patient minor response after one cycle (lung) six patients static disease. and nine patients progressive disease.
DISCUSSION BW 12C was developed for the treatment of sickle cell anaemia. Studies with patients with sickle cell disease (6) and with volunteers (4) showed that the OSC could be
Volume 22. Number 4, 1992
by up to 20% without significant toxicity. We modified have progressively increased the dose and length of infusion to give nearly 50% modification of the OSC, again without major toxicity. The most frequently noted side effect was irritation around the injection site, which could be reduced by further dilution of the drug or use of ante cubital fossa veins. The most significant side effect seen was a syncopal attack which occurred at the time of maximum modification but in a patient receiving only 35 mg/ kg of BW 12C. As this patient received a second dose without complication, it may have been caused by other factors such as anxiety. Significant falls in blood pressure were not observed in any other patients. An important question is whether the shifting of the OSC to the left by BW 12C will increase tissue or tumor hypoxia. Experimental studies with the Lewis lung tumor model showed that the radiobiological hypoxic fraction could be increased to almost 100% by a single dose of 70 mg/kg (1). Similarly, in an experimental T-cell lymphoma, BW 12C significantly increased the amount of tumor necrosis (1). Studies using a colon adenocarcinoma grown as a xenograft in nude mice found that BW 12C decreased the effect of single doses of Xrays similar to that resulting from clamping of the tumour blood supply (3). Similarly, in normal tissues BW 12C was found to reduce the effect of irradiation (dose modification factor of - 1.3) on both epidermis and haemopoiesis in mice, suggesting an increase in tissue hypoxia (1). We have started to investigate the degree of hypoxia induced by BW 12C by direct ~0, measurements in patients. Using a Sigma-Eppendorf ~0~ Histograph, measurements have been carried out in both normal tissues and tumor. Preliminary data have shown a fall in average pOZ of up to 62% in normal tissues and 64%) in tumor. A further question that we are about to address is whether the tumor hypoxia observed is caused solely by the left shift of the OSC or also caused by decreased blood flow, as experimental studies with RIF-1 leg tumors in mice showed a 64% reduction in blood flow after BW 12C injection (5). If these changes are occurring in human tumors, then the benefit of increased hypoxia may be counteracted by reduced uptake of MMC. Whether BW 12C will increase the efficacy of MMC has not been addressed in this study. The prototype bioreductive alkylating agent MMC (7) was chosen as it has an established role in cancer treatment. The overall response rate of 18% is similar to what one might expect to see with MMC alone (8). Note. however, that 7 of the 16 assessable patients had previously failed to respond to 5fluorouracil chemotherapy and thus comprised a poor prognostic group. Interestingly, in view of the changes in normal tissue oxygenation, no definite increase in MMC toxicity was seen compared to previous experience with MMC alone. Further randomized studies, however, will be necessary to see if the efficacy of bioreductive agents such as MMC can be enhanced by combination with BW12C.
BW12C with mitomycin
C 0 J. R. S. RAMSAY ei ul.
725
REFERENCES 1. Adams, G.; Barnes, D.; Du Boulay, C.; Loutit, J.; Cole, S.; Sheldon, P.: Stratford, I.; Van Den Aardweg, G.; Hopewek, J.; White, R.; Kneen, G.; Nethersell, A.; Edwards, C. Induction of hypoxia in normal and malignant tissues by changing the oxygen affinity of haemoglobin-implications for therapy. Int. J. Radiat. Oncol. Biol. Phys. 12: 1299-l 302; 1986. 2. Beddell, C.; Goodford, P.; Kneen, G.; White, R.; Wilkinson, S.; Wootton, R. Substituted benzaldehydes designed to increase the oxygen affinity of human haemoglobin and inhibit the sickling of sickle erythrocytes. Br. J. Pharmac. 82: 397407; 1984. 3. Cole, S.; Robbins, L. Manipulation of oxygenation in a human tumour xenograft with BW l2C or hydralazine: effects on responses to radiation and to the bioreductive cytotoxicity of misonidazole or RSU-1069. Radiother. Oncol. 16:235343; 1989. 4. Fitzharris, P.; McLean, A.; Sparks, R.; Weatherley. B.;
5.
6.
7.
8.
White, R.; Wootton, R. The effects in volunteers of BW12C, a compound designed to left-shift the blood-oxygen saturation curve. Br. J. Clin. Pharmac. 19:47 l-48 1; 1985. Honess, D.; White R.; Nethersell, A.; Bleehen, N. M. Effects of the manipulation of oxyhaemoglobin status by BW 12C on tumour thermosensitivity and on blood flow in tumour and normal tissue in mice. Int. J. Radiat. Oncol. Biol. Phys. 16: 1187-I 190; 1989. Keidan, A.; Franklin, I.; White, R.; Joy, M.; Huehns, E.; Stuart, J. Effect of BW I2C on oxygen affinity of haemoglobin in sickle cell disease. Lancet 1:83 l-834; 1986. Sartorelli, A. Therapeutic attack of hypoxic cells of solid tumours: presidential address. Cancer Res. 48:775-778; 1988. Sugarbaker, P.; Gunderson, L.; Wittes, R. Colorectal cancer. In: DeVita, V., Hellman, S., Rosenberg, S., eds. Cancer, principles and practice of oncology. Philadelphia: J. B. Lippincott Company: 1985:795-884.
22. pp.
72 1-725 Copynghi
0 Session E: Bioreductive PHASE
I STUDY PATIENTS
0360-3016/92 $5.00 + .Xl 0 1992 Pergamon Press plc
Therapies
OF BW12C IN COMBINATION WITH MITOMYCIN WITH ADVANCED GASTROINTESTINAL CANCER
C IN
J. R. S. RAMSAY, M.Sc., MRCP, FRCR,’ N. M. BLEEHEN, FRCP, FRCR, FACR(HON),’ I. DENNIS, B.Sc.,’ P. WORKMAN, PH.D.,’ R. WARD, B.Sc.,’ S. J. FALK, MRCP, FRCR,’ P. BEDFORD,
PH.D.,~
R. WOOTTON,
PH.D.~
AND A. B. W. NETHERSELL,
MRCP,
FRCR2
‘Medical Research Council Unit and University Department of Clinical Oncology and Radiotherapeutics, Hills Road, Cambridge CB2 2QH; ‘The Wellcome Research Laboratories, Langley Court, Beckenham, Kent BR3 3BS, UK. drug BW l2C with mitomycinC was investigatedin a Phase I study of 18 patients with advancedgastrointestinalcancer. The dose of BW12C was increased from 20 mg/kg to
The effect of combining the oxyhemoglobin-modifying
50 mg/kg to modify the hemoglobin-oxygen saturation curve by up to 48%. The period of maximum modification was then prolonged for up to 3 hr by a maintenance infusion of 4-6 mg/kg/hr. Pharmacokinetics of BW12C and mitomycin C were performed in all patients. Peak levels of BWl2C increased from 139 pg/ml to 378 pg/ml. Plasma half life was independent of dose, with an average of 3.3 hr. BW 12C was well tolerated with no severe side effects. Three patients had objective tumour responses. Mitomycin C, BWl2C, Hypoxia, Gastrointestinalcancer.
INTRODUCTION
METHODS
BW 12C (5-[2-formyl-3-hydroxyphenoxy] pentanoic acid*) is a substituted benzaldehyde designed to bind preferentially to oxyhemoglobin, stabilizing the molecule in a form that has a high affinity for oxygen. This process leads to a left shift in the oxygen saturation curve (OSC), thereby reducing the release of oxygen to the tissues (2,4). Animal studies have shown that it can increase tumor hypoxia and potentiates the antitumor activity of some bioreductive drugs ( 1, 3). The cytotoxic agent mitomycin C (MMC) has been used as a single agent or in combinations in the treatment of advanced gastrointestinal cancer (8). It is metabolized under reducing conditions to form a bifunctional alkylating agent which cross-links, and inhibits the synthesis of DNA. In studies with a variety of neoplastic cells, the drug was found to be more cytotoxic to hypoxic than to aerobic cells (7). It is thus hoped that the combination of MMC with BW 12C will result in greater efficacy. The purpose of this study is to monitor the safety of increasing doses of BW 12C in combination with MMC in patients with gastrointestinal cancer who have failed standard therapy. In association with this, we have measured the changes in the OSC caused by BW 12C and the pharmacokinetics of MMC and BW 12C.
AND MATERIALS
Patient selection Eighteen patients (age 36-69) with progressive metastatic gastrointestinal cancer have been entered into the study. Primary disease was colorectal adenocarcinoma in 17 patients and adenocarcinoma of stomach in 1 patient. Seventeen patients had previous surgery, seven previous radiotherapy and seven previous chemotherapy with 5fluorouracil. All patients had WHO status I 2, hemoglobin 2 lOg/lOO ml, white cell count L 4 X 109/L, and platelets 2 100 X 109/L. There was no history of ischaemic heart disease or cerebrovascular disease, and all patients gave written informed consent. Pre-trial patients underwent full clinical examination with radiological assessment of disease extent. On the day of treatment patients were closely monitored for toxicity and any adverse effects recorded. Patients were subsequently assessed I and 4 weeks after treatment. Patients not showing progressive disease or clinical deterioration proceeded to a second course of treatment after 6 weeks.
Drug administration Cohorts of two patients were treated with a 1 hr infusion of BW 12C, commencing at a dose of 20 mg/kg. The dose was escalated in the first four cohorts up to 40 mg/kg.
Presented at the Seventh International Conference on Chemical Modifiers of Cancer Treatment, Clearwater, FL, 2-5 February 1991.
Reprint requests to: Professor N. M. Bleehen. Accepted for publication 26 July 199 1. * Wellcome Ltd., UK. 721
I.
J. Radiation
Oncology
0 Biology 0 Physics
Volume
22, Number
4, 1992
50
20
0
0
10
0 0
60
120 minutes
120
180 240 minutes
160
1 40
Dose Fig. 1. Percent of hemoglobin of BW12C in 18 patients.
BW12C modification
mglkg
mglkg at escalating
dose
The next three cohorts received a loading infusion of 40 mg/kg followed by a maintenance infusion of 6 mg/kg/ hr increased from 1 to 3 hr to prolong the maximum modification of the OSC. The final two cohorts were treated with 45 and 50 mg/kg loading infusion with a maintenance infusion of 4 mg/kg/h over 3 hr. MMC was administered as an intravenous bolus at a dose of 20 mg/m2 immediately at the end of the BW 12C infusion.
Modijcution of’haemoglobin-oxygen saturution curve Blood samples were collected at 0, 30, and 60 min during the loading infusion, hourly during the maintenance infusion, and 30, 60, and 120 min thereafter. Samples were kept on ice and transported within 24 hr to the Wellcome Research Laboratories for analysis. The whole blood oxygen saturation curve was measured by a spectrophotometric technique. Each post-BW 12C infusion curve was analyzed by comparison with a series of artificially constructed curves calculated from the equation of Beddell et al. (2). The proportion of BW 12C reacted hemoglobin (percentage modification) was determined from the artificial curve that corresponded to the observed post-infusion curve.
0
60
40
mglkg
300
360
, maintenance
at
Gmglkglh
Fig. 2. Percent of hemoglobin modified in pairs of typical patients on 40 mg/kg infusion over 1 hr (a) or with additional maintenance at 6 mg/kg/hr for subsequent 3 hr (b).
Blood sample analysis BW 12C was extracted from whole blood by addition of water to form a hemolysate, followed by acidification
BWl2C
Table 1. Pharmacokinetics
with mitomycin
C 0 .I. R. S. RAMSAY
of BW12C in haemolysate
Dose mg kg-’
Maintenance h
No. of courses
Peak cone pg ml-’
20
-
3
158 (109-187) 270 (227-3 13) 348 (285-434) 335 (3 15-348) 287 (25&334) 272 (252-29 1) 378 (308-448) 355 (275434) 334 (323-344)
30
3
35
4
40
-
3
40
1
3
40
2
2
40
3
3
45
3
3
50
3
2
with hydrochloric acid, and then protein precipitation with acetonitrile. MMC was extracted from plasma using Waters? C 18 Sep-paks. BW 12C and MMC drug concentrations were assayed by reverse phase HPLC, with U.V. detection at 280 nm for BW 12C and 365 nm for MMC. Separations were achieved on a Waters Nova-Pak (4 pm) Rad-Pak column. Each drug was eluted using an appropriate gradient of methanol/sodium phosphate buffer.
RESULTS
Mocljication qf haemoglobin-oxygen
saturation curves
There was a dose-related increase in percentage modification with increasing dose of BW 12C from 20 to 50 mg/kg (Fig. 1). The maximum modification obtained at the end of the infusion was 42%. In one patient treated at 45 mg/kg a modification of only 18% was obtained which was associated with a low BW 12C peak plasma level of 270 pg/ml. For patients treated with a loading infusion only, the maximum modification occurred at the end of the infusion or 30 min after completion (Fig. 2a). Patients receiving a maintenance infusion of 6 mg/ kg/hr had the period of modification prolonged for over 4 hr. There was, however, a slow increase in the degree of modification during the maintenance infusion in some patients (Fig. 2b). For this reason the dose was reduced to 4 mg/kg/h for the final four patients. This has given a more stable maximum degree of modification during the infusion.
t Waters division
of Millipore,
Milford,
MA, U.S.A.
723
et (I/.
(26 courses in 18 patients) tu2
h 1.93 (1.73-2.15) 3.39 (2.624.78) 3.29 (2.80-3.57) 3.90 (2.984.55) 2.96 (2.38-3.88) 3.61 (2.904.32) 2.83 (2.77-2.88) 3.56 (2.60-4.53) 4.08 (3.794.36)
AUC,.,
pg ml-’ h 570 (360-760) 1480 (1280-1810) 1840
(1550-2290) 2570 ( 1960-2970) 1610 (1270-2170) 1990 ( 1540-2450) 2550 (2020-3080) 2786 (1620-3952) 2686 (2570-2800)
Pharmacokinetics BW 12C haemolysate pharmacokinetics are summarized in Table 1. Peak levels increased with dose from a mean of around 139 pg/ml at 20 mg/kg to 378 pg/ml at 40 mg/ kg. The AU&,. increased with dose. The elimination half-life was independent of dose at around 3.3 hr. Repeat pharmacokinetics within patients were very reproducible (not shown). The plasma pharmacokinetics of MMC were as expected. The mean concentration at 15 min post-injection was 0.96 pg/ml (range 0.71-1.31 pg/ml). Values of tliza and t,,$ were 0.24 h (0.054-0.96 h) and 1.15 h (0.433.02 h), respectively. The mean AUCo_& value was 1.07 pg/ml h (0.77-I .42 pg/ml h). Haemolysate BW 12C and plasma MMC pharmacokinetics for a patient receiving a dose of 40 mg/kg of BW 12C with a 3-hr maintenance infusion are illustrated in Figure 3. In three patients for whom it was possible to obtain plasma samples for MMC with and without BW 12C, the kinetic parameters were closely similar.
Toxicity Adverse effects of BW 12C were only seen on the day of treatment with no prolonged or delayed effects. Six patients had some pain or erythema around the injection site. This was usually mild and only in one patient was the infusion temporarily stopped with relief of his symptoms. The effect was seen most frequently with patients receiving the higher doses and was related to the concen-
724
1. J. Radiation Oncology 0 Biology 0 Physics
0 -4
-2
0
2
Time (h) from end of infusion Fig. 3. Pharmacokinetics of a typical patient. Concentration of BW 12C (0) in hemolysate and MMC (A) in plasma following 40 mg/kg infusion over 1 hr with maintenance of BW 12C 6 mg/ kg/hr over subsequent 3 hr. MMC was given at end of maintenance infusion of BW 12C.
of drug in the loading infusion. Other side effects recorded were headache (one patient), nausea and vomiting (one patient), sinus tachycardia (one patient) and syncope (one patient). The latter occurred in a patient receiving 35 mg/kg and was not observed when a second dose was administered. MMC toxicity was limited to myelosuppression with a maximum WHO grade 2 Hb toxicity (two patients), grade 2 neutropaenia (one patient) and grade 3 platelet toxicity (one patient). There were no cases of sepsis, bleeding, or treatment-related deaths. tration
C’linicul response Patients were assessed for clinical response after 4 to 6 weeks. Those demonstrating obvious progressive disease or clinical deterioration were removed from the study. Eight patients with stable or responding disease proceeded with a second course of treatment giving the same doses and with repeat pharmacokinetics. One patient had a complete response after two cycles (anastomotic recurrence), one patient a partial response after two cycles (liver), one patient minor response after one cycle (lung) six patients static disease. and nine patients progressive disease.
DISCUSSION BW 12C was developed for the treatment of sickle cell anaemia. Studies with patients with sickle cell disease (6) and with volunteers (4) showed that the OSC could be
Volume 22. Number 4, 1992
by up to 20% without significant toxicity. We modified have progressively increased the dose and length of infusion to give nearly 50% modification of the OSC, again without major toxicity. The most frequently noted side effect was irritation around the injection site, which could be reduced by further dilution of the drug or use of ante cubital fossa veins. The most significant side effect seen was a syncopal attack which occurred at the time of maximum modification but in a patient receiving only 35 mg/ kg of BW 12C. As this patient received a second dose without complication, it may have been caused by other factors such as anxiety. Significant falls in blood pressure were not observed in any other patients. An important question is whether the shifting of the OSC to the left by BW 12C will increase tissue or tumor hypoxia. Experimental studies with the Lewis lung tumor model showed that the radiobiological hypoxic fraction could be increased to almost 100% by a single dose of 70 mg/kg (1). Similarly, in an experimental T-cell lymphoma, BW 12C significantly increased the amount of tumor necrosis (1). Studies using a colon adenocarcinoma grown as a xenograft in nude mice found that BW 12C decreased the effect of single doses of Xrays similar to that resulting from clamping of the tumour blood supply (3). Similarly, in normal tissues BW 12C was found to reduce the effect of irradiation (dose modification factor of - 1.3) on both epidermis and haemopoiesis in mice, suggesting an increase in tissue hypoxia (1). We have started to investigate the degree of hypoxia induced by BW 12C by direct ~0, measurements in patients. Using a Sigma-Eppendorf ~0~ Histograph, measurements have been carried out in both normal tissues and tumor. Preliminary data have shown a fall in average pOZ of up to 62% in normal tissues and 64%) in tumor. A further question that we are about to address is whether the tumor hypoxia observed is caused solely by the left shift of the OSC or also caused by decreased blood flow, as experimental studies with RIF-1 leg tumors in mice showed a 64% reduction in blood flow after BW 12C injection (5). If these changes are occurring in human tumors, then the benefit of increased hypoxia may be counteracted by reduced uptake of MMC. Whether BW 12C will increase the efficacy of MMC has not been addressed in this study. The prototype bioreductive alkylating agent MMC (7) was chosen as it has an established role in cancer treatment. The overall response rate of 18% is similar to what one might expect to see with MMC alone (8). Note. however, that 7 of the 16 assessable patients had previously failed to respond to 5fluorouracil chemotherapy and thus comprised a poor prognostic group. Interestingly, in view of the changes in normal tissue oxygenation, no definite increase in MMC toxicity was seen compared to previous experience with MMC alone. Further randomized studies, however, will be necessary to see if the efficacy of bioreductive agents such as MMC can be enhanced by combination with BW12C.
BW12C with mitomycin
C 0 J. R. S. RAMSAY ei ul.
725
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