Intraperitoneal Yttrium-90-Labeled Monoclonal Antibody in Ovarian Cancer By J.S.W. Stewart, V. Hird, D. Snook, B. Dhokia, G. Sivolapenko, G. Hooker, J. Taylor Papadimitriou, G. Rowlinson, M. Sullivan, H.E. Lambert, C. Coulter, W.P. Mason, W.P. Soutter, and A.A. Epenetos From March 1987 to March 1988, a phase I to II study was carried out in 25 patients with ovarian cancer. They received escalating doses of intraperitoneally (IP) administered yttrium-90 (Y-90)-labeled monoclonal antibody, HMFG1, against a tumor cell-surface antigen. Myelosuppression prevented an escalation of the administered Y-90 activity above 25 mCi. Y-90labeled antibody was absorbed from the peritoneal cavity into the circulation. Maximum blood Y-90 activity was observed 40 hours after the IP injection with a mean of 21% of the injected activity (range, 14.2% to 26.4%) in the circulation. The radiation dose the bone marrow received from circulating Y-90-labeled antibody (the blood radiation dose) was calculated by applying the Medical Internal Radiation Dose (MIRD) formulation to the measured Y-90 activity in patients
C
YTOREDUCTIVE surgery and postopera-
tive chemotherapy for ovarian carcinoma in the last 10 years have produced combined response rates of 65% to 80%.'-3 Although overall median survival has been increased, many patients eventually relapse, 4 so that long-term survival remains unchanged. 5 Further progress in treating this disease depends on developing a treatment modality that can eradicate the last remnants of tumor after surgery and chemotherapy. Although radiotherapy has a well-established role in destroying microscopic disease in many anatomic sites, its role in ovarian cancer remains controversial. The increased survival that has been reported in patients undergoing whole abdominal radiotherapy only applies to certain patient categories. 6 Those patients who have not received previous chemotherapy, have favorable histology and/or a small disease volume after surgery do well. The benefit in the majority of patients who have required chemotherapy is less certain. 7 The radiation dose that can be delivered to the whole abdomen is limited by the tolerance of the small bowel, liver, and kidneys. This means that most of the peritoneal cavity receives less than 30 Gy in 20 fractions over 4 weeks, 6 rather less than that normally
blood. Myelosuppression occurred following calculated blood radiation doses to bone marrow of only 10 to 30 cGy. The excessive myelosuppression following such modest radiation doses from circulating Y-90labeled antibody could be explained by the uptake of Y-90 by bone. In an attempt to reduce bone absorption of Y-90, seven patients received an intravenous (IV) infusion of EDTA (Sinclair Pharmaceuticals Ltd, Godalming, United Kingdom). This increased the urinary excretion of Y-90 from a mean of 11.1% to 32.3% of the injected activity (P = .0001). Fourteen patients had assessable tumor at laparoscopy. Tumor regression was observed in one patient, and palliation of ascites in a further patient. J Clin Oncol 8:1941-1950. o 1990 by American Society of ClinicalOncology. recommended for the control of microscopic carcinoma. In the last 10 years, numerous monoclonal antibodies (MAbs) have been developed against a wide range of tumor-associated antigens. Tumors can be imaged by intravenously (IV) injecting radioactive isotopes of indium (In-ill), or iodine (1-123 or 1-131)-labeled antibody. 9 "-1 De-
spite successful immunoscintigraphy studies, the tumor to normal tissue ratios range from 3:1 to 9:1,10,12 with less than 0.001% of the injected isotope activity targeted to each gram of tumor.12 Successful radioimmunotherapy with IV radiolabeled antibody administration is impossible unless the amount of targeted isotope can be in-
From the Imperial Cancer Research Fund, Department of Clinical Oncology, Departmentof Gynaecology, and Department of Ilmmunology, Royal PostgraduateMedical School, Hammersmith Hospital,London; and Departmentsof Gynaecology and Oncology, St Mary's Hospital, London, United Kingdom. Submitted October 30, 1989; accepted May 24, 1990. Address reprint requests to A.A. Epenetos, PhD, ICRF Oncology Group, Department of Clinical Oncology, Royal PostgraduateMedical School, Hammersmith Hospital,Du Cane Rd, London W11 OHS, United Kingdom. © 1990 by American Society of Clinical Oncology. 0732-183X/90/0812-0007$3.00/0
Journal of Clinical Oncology, Vol 8, No 12 (December), 1990: pp 1941-1950
Downloaded from ascopubs.org by 5.62.155.97 on February 10, 2017 from 005.062.155.097 Copyright © 2017 American Society of Clinical Oncology. All rights reserved.
1941
1942
STEWART ET AL
creased at least 10-fold. 12 ,13 However, when tumors such as ovarian cancer are anatomically confined to a body cavity, intracavitary rather than IV injection of radiolabeled MAb may be more logical. Since 1983 we have been developing and optimizing a new treatment modality for ovarian cancer. 8 Studies of animals bearing human intraperitoneal (IP) tumors have indicated that greater levels of isotope can be targeted when the radiolabeled antibody is injected by the IP rather than the IV route.14 This IP to IV advantage has also been described in humans,15' 16 and tumoricidal isotope activities have been detected on free-floating malignant cells in the peritoneal cavity.' 7 We have reported encouraging results in patients with malignant pleural effusions following the intrapleural injection of I-131-labeled antibody.' 8 Although we observed the regression of microscopic tumor deposits in a study of IP I-131-labeled MAb in patients with ovarian cancer,19 the response of larger tumor nodules was disappointing.20 Although 1-131 was the first isotope used in radioimmunotherapy (RIT) (due to the wellestablished methods of protein iodination) it may not be the most suitable radiolabel. I-131 emits unwanted gamma radiation, and its beta particles are of low energy (Emax 0.6 MeV) with a limited range in tissue. 2 1,22 The biologic half-life of I-131 in tumor deposits may be decreased by tumor dehalogenases. 23 Yttrium-90 (Y-90) has been suggested as an alternative isotope, as it is a pure beta emitter (Emax 2.3 MeV), and not subject to dehalogenation. The half-life of Y-90 is a third of that of I-131 (64 hours v 193 hours) allowing a greater fraction of the physical decay to occur in the peritoneal cavity. Recently MAbs have been successfully labeled with Y-90 using the bifunctional chelate diethylenetriamine pentaacetic acid (DPTA). 24 Biodistribution studies of IP administered Y-90-labeled MAb have been reported in patients with ovarian cancer, 25 and Y-90-1labeled MAb has been used to treat patients with hepatoma.2 6 This report describes a phase I-II trial of IP administered Y-90 MAb in patients with ovarian cancer. We describe the pharmacokinetics of IP radiolabeled antibody, the toxicity of the immunoconjugate, and provide limited therapeutic response data.
METHODS PatientDetails Between March 1987 and March 1988, 25 patients with known epithelial ovarian cancer received IP radioimmunotherapy with Y-90 MAb. Patients' ages ranged from 36 to 75 years, all had previously undergone cytoreductive surgery followed by chemotherapy for stage III disease. Fifteen patients had received four to six cycles of cisplatin chemotherapy (80 mg/m2), six patients had received five to 10 (mean, 6.5) cycles of carboplatin (400 mg/m2), and one patient had received treosulfan chemotherapy. Two of these patients had also received whole abdominal external beam radiotherapy (24 Gy in 20 fractions to the whole abdomen with a pelvic boost to 45 Gy). In addition, three patients with less advanced ovarian cancer (stage Ic, stage Ia [ruptured cyst], and stage Ib") who declined chemotherapy received RIT. None of these patients had been exposed to mouse immunoglobulin (Ig) previously, and all had negative human antimouse Ig titers. This study was approved by the Hammersmith Hospital Ethics Committee, and written informed consent was obtained from all patients. The quantity of tumor and the response to RIT were assessed by laparoscopy rather than laparotomy as the latter was considered to be too invasive a method of investigation in this group of patients, and may have led to fibrin deposition on the peritoneal surface that could nonspecifically bind MAb. Patients were divided into four groups depending on the amount of residual disease prior to RIT (Table 1). Three patients had bulky residual tumor with tumor nodules greater than 2 cm diameter, 10 patients had small nodules less than 2 cm diameter, one patient had positive peritoneal cytology, and 11 patients had no visible tumor at laparoscopy following surgery ± chemotherapy.
MAb The MAbs used in this study were human milk fat globule 1 (HMFG1 and AUA1; Unipath, Bedford, UK, Ltd). HMFG1 is a mouse IgGI MAb that binds to a mucin molecule found on more than 90% of serous papillary ovarian carcinomas."27 28 The antibody AUA1 binds to a 35 kd cell-surface antigen found on the colonic cancer cell line LoVo, but also expressed by 75% of ovarian cancers. 29'3 HMFG I was used alone in 22 patients, AUA1 in one patient, and a cocktail of both antibodies in two patients. Before patients were considered suitable for RIT, the original tumor histology was examined for positive immunoperoxidase staining by these antibodies. Both these antibodies can be used to identify antigens in tissue that has been formalin fixed, and preserved in wax; this was important as fresh tissue is not always available. Suitable patients had more than 50% of their tumor cells (from at least 10 random high-power fields) express antigens that bound to either HMFGI or AUAI. Patients received between 14.6 and 34.6 mg of labeled antibody, with a mean of 18 mg (Table 1). Most patients received HMFGI, AUA1 alone was used in one patient whose tumor did not express HMFGI antigen, and AUAI and HMFGI were used together in two patients whose tumors strongly expressed both antigens.
Downloaded from ascopubs.org by 5.62.155.97 on February 10, 2017 from 005.062.155.097 Copyright © 2017 American Society of Clinical Oncology. All rights reserved.
1943
Y-90-LABELED ANTIBODY IN OVARIAN CANCER Table 1. Patient, Treatment, and Response Data in Patients Receiving IP Y-90 HMFG 1 Tumor Size in Centimeters
Amount of MAb (mg)
Yttrium-90 Activity (MCi)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
< 2 cm None seen < 2 cm < 2 cm < 2 cm None seen < 2 cm None seen > 2 cm Positive cytology None seen None seen None seen None seen None seen < 2 cm None seen Ascites < 2 cm None seen Noneseen
22 23 24
> 2 cm < 2 cm < 2 cm
25
< 2 cm
30 16.8 20 20 20 20 20 20 18 28 20 25 24 20 18 28* 15 23 16 18 18 17* 14.6 18.2 19 15.6* 23
5 16.4 12.5 15 15 15 15.1 16.9 20 6 15 17.6 17.7 16.8 18.2 18.4 21 25.2 20.3 19.6 11.3 11.3 18.2 20.6 6.2 6.1 20.6
Patient No.
Tumor Response Partial response Disease-free at 15 months Progressive disease Progressive disease Progressive disease Disease-free at 12 months Progressive disease Progressive disease Progressive disease Progressive disease Disease-free at 6 months Disease-free at 12 months Disease-free at 12 months Disease-free at 9 months Disease-free at 9 months Progressive disease Disease-free at 6 months Progressive disease Progressive disease Disease-free at 9 months Disease-free at 6 months Progressive disease Progressive disease Progressive disease Disease-free at 6 months
*AUA1 instead of HMFG1.
Antibody Labeling Y-90 (Unipath Ltd, United Kingdom) was supplied by Atomic Energy Research Establishment, Harwell, Berkshire, United Kingdom, from a strontium-90 generator. Strontium contamination accounted for less than 1 part per 105 to 10'. The yttrium was chelated to the antibody/DPTA complex as described by Hnatowich et al. 24 Free yttrium was removed by Sephadex G-50 (Pharmacia LKB, Biotechnology AB, Uppsala, Sweden) gel filtration using phosphate-buffered saline pH 7.4. Antibody immunoreactivity was tested by an enzymelinked immunoadsorbent assay (ELISA) method before and after radiolabeling, on microtiter plates coated with purified antigen and compared with underivatized antibody." No significant difference was seen between the two. The administered dose was measured in a SIEL isotope calibration chamber (SIEL Imaging EQ Ltd, Aldermaston, Berks, England) that had been calibrated with an yttrium source. Treatment Details Peritoneal dialysis catheters were inserted into the peritoneal cavity at open laparoscopy. Open laparoscopy also allowed the placement of thermoluminescent dosimetry (TLD) catheters (see below), and a visual assessment of disease volume including peritoneal lavage with 50 mL of 0.9% saline
for cytologic assessment. Minor adhesions particularly around the liver were noted in most patients, but a good view (all four quadrants of the peritoneal cavity) was obtained in all but one patient. This patient had many peritoneal adhesions and has not been included in this series. Two patients had small perforations of the bowel, which occurred at laparoscopy, and were immediately identified. These were sutured without further complication and the patients treated. The Y-90labeled antibody was infused into the peritoneal cavity with 1.5 L of 0.9% saline. Following the infusion, the peritoneal dialysis catheter was removed, and the patient's position altered every 20 minutes to encourage an even IP distribution of antibody. Patients were nursed in a radiation-controlled area for 5 days during which blood samples were taken at 12 hourly intervals for Y-90 activity, and urine collected to monitor Y-90 excretion. During this study it became apparent that bone concentration of Y-90 following antibody catabolism was contributing to myelosuppression. In an attempt to reduce the uptake of Y-90 by bone, the last seven patients received IV EDTA (Sinclair Pharmaceuticals Ltd, Godalming, United Kingdom) after the IP infusion of Y-90-labeled antibody. EDTA was infused IV (40 mg/m 2 over 4 hours) at 14, 26, 38, 50, 62, and 74 hours after the IP administration of Y-90-labeled antibody. EDTA infusions were accompanied by IV fluids to ensure a daily urine output of a least 2 L.
Downloaded from ascopubs.org by 5.62.155.97 on February 10, 2017 from 005.062.155.097 Copyright © 2017 American Society of Clinical Oncology. All rights reserved.
1944
STEWART ET AL
Pharmacokineticsand Dosimetry In 20 patients the blood and urine Y-90 activities were measured in a scintillation well counter, comparing the "bremsstrahlung" x-rays with those of known Y-90 standards in identical containers. The Y-90 activity in each patient's circulation was extrapolated from that of the measured blood samples by estimating each patient's blood volume from their surface area.3 For each patient, a plot of whole blood Y-90 activity against time (100 hours after RIT) was constructed. The area under this curve (AUC) in microcurie-hours of Y-90 activity, was used to estimate the radiation dose the bone marrow received from Y-90-labeled antibody in the marrow circulation according to the Medical Internal Radia32 Marrow is extremely tion Dose (MIRD) formulation. vascular and macromolecules rapidly reach equilibrium with 34 33 the blood. Active marrow constitutes 2.2% of body weight, that is, 25% to 31% of the blood weight, and for these calculations, the Y-90 activity actually in the marrow was assumed to be 20% of the integrated blood activity. The estimated bone marrow dose in cGy was calculated using A x S where A is the cumulative Y-90 activity (in marrow) expressed as microcurie hours and S is the S value for marrow 32 as a source and target organ. Y-90 activities were corrected for radioactive decay when expressing the pharmacokinetics of Y-90-labeled antibody in blood and urine to facilitate comparison with other radiolabels. The fraction of Y-90 activity bound to protein in the blood was measured in six patients by Sephadex gel filtration of serum at 14, 38, 62, 87, and 110 hours. The pharmacokinetics of the patient with ascites (patient no. 18) was not included in this study as patients with ascites absorb less radiolabeled antibody from the peritoneal cavity (probably due to lymphatic obstruction). This totally changes the dosimetry to the bone marrow and peritoneal serosa. In 10 patients, the radiation dose to the peritoneal serosa from nontargeted Y-90-labeled antibody was measured by lithium fluoride (LiF) TLD. We were unable to biopsy tumor deposits after treatment but would assume that they received a high radiation dose due to antibody targeting. The TLD measurements from two ovarian cancer patients who received IP Y-90 silicate colloid (Amersham International Plc, Amersham, United Kingdom) are also included for comparison. Both patients had diffuse small peritoneal tumor nodules following chemotherapy and received 50 mCi of Y-90 silicalte colloid. For each patient, 20 to 35 LiF rods each 6 x 1 mm (TLD-100) (Harshaw/Filtrol Partnership, OH) were placed in a plastic tube of wall thickness 0.1 mm. The tube was heat sealed and sterilized before being inserted into the peritoneal cavity at laparoscopy. The TLD catheter remained in situ for 110 hours before being removed, and the light output of each rod measured in a 654A Toledo TLD reader (Vinten Instruments Ltd, Surrey, United Kingdom). The TLD rods were calibrated by immersing representative samples in a solution containing a known activity of Y-90 for time intervals. This calibration closely agreed with independent calibrations using known radiation doses from 4 MeV electrons delivered by a linear accelerator. Response Laparoscopy was used to assess tumor response 8 to 12 weeks after treatment, unless patients had already developed progressive disease clinically. Pre- and posttreatment lap-
aroscopies were all performed by one of the authors (V.H.) to facilitate the comparison of tumor deposits following treatment. Responses were divided into complete response (CR), the disappearance of all tumor, and partial response (PR), a 50% reduction in tumor volume. Otherwise, disease was categorized as progressive disease (PD) as it was difficult to accurately determine minimal regression or stable disease at laparoscopy.
Toxicity Patients were reviewed weekly for at least 6 weeks after treatment to assess toxicity. Hematologic and biochemical parameters were assessed, along with liver function tests and antibody titers to the mouse MAb (human antimouse antibody [HAMA]). Blood counts were graded into five grades according to the World Health Organization (WHO) classification" (Table 2). Bone marrow suppression was given an arbitrary score of the sum of the WHO grades for neutropenia and thrombocytopenia.
Statistics A nonparametric statistical analysis, the Mann-Whitney U test, was used to test the significance between different groups of pharmacokinetic data.
RESULTS
Pharmacokinetics Y-90 activity was detected in patients' circulation following the IP administration of Y-90labeled antibody (Fig 1). Peak blood activity was observed at 40 hours with a mean of 21.3% (range, 13.9% to 29%; N = 21 patients) of the injected Y-90 activity in the circulation. Sephadex G-50 gel filtration of serum from six patients indicated that a mean of 97.4% (range, 99.7% to 93.2%; N = 32 measurements) of the Y-90 activity was bound to protein, and affinity chromatography with rabbit antimouse Ig, confirmed this protein to be murine antibody. Following peak blood radioactivity, Y-90-labeled antibody was cleared exponentially from the circulation with a mean biologic half-life of 50 hours (range, 30 to 84 hours; N = 21). Patients who received an IV EDTA infusion appeared to have slightly lower circulating Y-90 activity (Fig 1). A MannWhitney analysis of the AUCs (percentage of Table 2. WHO Grades for Neutropenia and Thrombocytopenia WHO Grade Count
Platelet Count IO0/L
Neutrophil 106/L
0
>100
>4
1 2 3 4
75-99 50-74 25-49 < 25
3-3.9 2-2.9 1-1.9 < 1
Downloaded from ascopubs.org by 5.62.155.97 on February 10, 2017 from 005.062.155.097 Copyright © 2017 American Society of Clinical Oncology. All rights reserved.
1945
Y-90-LABELED ANTIBODY IN OVARIAN CANCER
0
10.3 cGy to 46.2 cGy following the administration of 5 to 19.2 mCi of Y-90-labeled antibody, respectively (Fig 3).
20
RadiationDose to Peritoneum 10 II
z
Ca
a, 0 O
0
-
0
20
40
60
80
100
Hours after IP infusion Fig 1. Blood Y-90 expressed as percentage of injected activity (coarrected for radioactive decay). (0) All patients; M with IV EDTTA; (A)without ETDA.
injected dose x time) between patients receiving and not receiving EDTA confirmed this tendency, although this was not statistically significant (Mann-Whitney U = 30, .1
C
YTOREDUCTIVE surgery and postopera-
tive chemotherapy for ovarian carcinoma in the last 10 years have produced combined response rates of 65% to 80%.'-3 Although overall median survival has been increased, many patients eventually relapse, 4 so that long-term survival remains unchanged. 5 Further progress in treating this disease depends on developing a treatment modality that can eradicate the last remnants of tumor after surgery and chemotherapy. Although radiotherapy has a well-established role in destroying microscopic disease in many anatomic sites, its role in ovarian cancer remains controversial. The increased survival that has been reported in patients undergoing whole abdominal radiotherapy only applies to certain patient categories. 6 Those patients who have not received previous chemotherapy, have favorable histology and/or a small disease volume after surgery do well. The benefit in the majority of patients who have required chemotherapy is less certain. 7 The radiation dose that can be delivered to the whole abdomen is limited by the tolerance of the small bowel, liver, and kidneys. This means that most of the peritoneal cavity receives less than 30 Gy in 20 fractions over 4 weeks, 6 rather less than that normally
blood. Myelosuppression occurred following calculated blood radiation doses to bone marrow of only 10 to 30 cGy. The excessive myelosuppression following such modest radiation doses from circulating Y-90labeled antibody could be explained by the uptake of Y-90 by bone. In an attempt to reduce bone absorption of Y-90, seven patients received an intravenous (IV) infusion of EDTA (Sinclair Pharmaceuticals Ltd, Godalming, United Kingdom). This increased the urinary excretion of Y-90 from a mean of 11.1% to 32.3% of the injected activity (P = .0001). Fourteen patients had assessable tumor at laparoscopy. Tumor regression was observed in one patient, and palliation of ascites in a further patient. J Clin Oncol 8:1941-1950. o 1990 by American Society of ClinicalOncology. recommended for the control of microscopic carcinoma. In the last 10 years, numerous monoclonal antibodies (MAbs) have been developed against a wide range of tumor-associated antigens. Tumors can be imaged by intravenously (IV) injecting radioactive isotopes of indium (In-ill), or iodine (1-123 or 1-131)-labeled antibody. 9 "-1 De-
spite successful immunoscintigraphy studies, the tumor to normal tissue ratios range from 3:1 to 9:1,10,12 with less than 0.001% of the injected isotope activity targeted to each gram of tumor.12 Successful radioimmunotherapy with IV radiolabeled antibody administration is impossible unless the amount of targeted isotope can be in-
From the Imperial Cancer Research Fund, Department of Clinical Oncology, Departmentof Gynaecology, and Department of Ilmmunology, Royal PostgraduateMedical School, Hammersmith Hospital,London; and Departmentsof Gynaecology and Oncology, St Mary's Hospital, London, United Kingdom. Submitted October 30, 1989; accepted May 24, 1990. Address reprint requests to A.A. Epenetos, PhD, ICRF Oncology Group, Department of Clinical Oncology, Royal PostgraduateMedical School, Hammersmith Hospital,Du Cane Rd, London W11 OHS, United Kingdom. © 1990 by American Society of Clinical Oncology. 0732-183X/90/0812-0007$3.00/0
Journal of Clinical Oncology, Vol 8, No 12 (December), 1990: pp 1941-1950
Downloaded from ascopubs.org by 5.62.155.97 on February 10, 2017 from 005.062.155.097 Copyright © 2017 American Society of Clinical Oncology. All rights reserved.
1941
1942
STEWART ET AL
creased at least 10-fold. 12 ,13 However, when tumors such as ovarian cancer are anatomically confined to a body cavity, intracavitary rather than IV injection of radiolabeled MAb may be more logical. Since 1983 we have been developing and optimizing a new treatment modality for ovarian cancer. 8 Studies of animals bearing human intraperitoneal (IP) tumors have indicated that greater levels of isotope can be targeted when the radiolabeled antibody is injected by the IP rather than the IV route.14 This IP to IV advantage has also been described in humans,15' 16 and tumoricidal isotope activities have been detected on free-floating malignant cells in the peritoneal cavity.' 7 We have reported encouraging results in patients with malignant pleural effusions following the intrapleural injection of I-131-labeled antibody.' 8 Although we observed the regression of microscopic tumor deposits in a study of IP I-131-labeled MAb in patients with ovarian cancer,19 the response of larger tumor nodules was disappointing.20 Although 1-131 was the first isotope used in radioimmunotherapy (RIT) (due to the wellestablished methods of protein iodination) it may not be the most suitable radiolabel. I-131 emits unwanted gamma radiation, and its beta particles are of low energy (Emax 0.6 MeV) with a limited range in tissue. 2 1,22 The biologic half-life of I-131 in tumor deposits may be decreased by tumor dehalogenases. 23 Yttrium-90 (Y-90) has been suggested as an alternative isotope, as it is a pure beta emitter (Emax 2.3 MeV), and not subject to dehalogenation. The half-life of Y-90 is a third of that of I-131 (64 hours v 193 hours) allowing a greater fraction of the physical decay to occur in the peritoneal cavity. Recently MAbs have been successfully labeled with Y-90 using the bifunctional chelate diethylenetriamine pentaacetic acid (DPTA). 24 Biodistribution studies of IP administered Y-90-labeled MAb have been reported in patients with ovarian cancer, 25 and Y-90-1labeled MAb has been used to treat patients with hepatoma.2 6 This report describes a phase I-II trial of IP administered Y-90 MAb in patients with ovarian cancer. We describe the pharmacokinetics of IP radiolabeled antibody, the toxicity of the immunoconjugate, and provide limited therapeutic response data.
METHODS PatientDetails Between March 1987 and March 1988, 25 patients with known epithelial ovarian cancer received IP radioimmunotherapy with Y-90 MAb. Patients' ages ranged from 36 to 75 years, all had previously undergone cytoreductive surgery followed by chemotherapy for stage III disease. Fifteen patients had received four to six cycles of cisplatin chemotherapy (80 mg/m2), six patients had received five to 10 (mean, 6.5) cycles of carboplatin (400 mg/m2), and one patient had received treosulfan chemotherapy. Two of these patients had also received whole abdominal external beam radiotherapy (24 Gy in 20 fractions to the whole abdomen with a pelvic boost to 45 Gy). In addition, three patients with less advanced ovarian cancer (stage Ic, stage Ia [ruptured cyst], and stage Ib") who declined chemotherapy received RIT. None of these patients had been exposed to mouse immunoglobulin (Ig) previously, and all had negative human antimouse Ig titers. This study was approved by the Hammersmith Hospital Ethics Committee, and written informed consent was obtained from all patients. The quantity of tumor and the response to RIT were assessed by laparoscopy rather than laparotomy as the latter was considered to be too invasive a method of investigation in this group of patients, and may have led to fibrin deposition on the peritoneal surface that could nonspecifically bind MAb. Patients were divided into four groups depending on the amount of residual disease prior to RIT (Table 1). Three patients had bulky residual tumor with tumor nodules greater than 2 cm diameter, 10 patients had small nodules less than 2 cm diameter, one patient had positive peritoneal cytology, and 11 patients had no visible tumor at laparoscopy following surgery ± chemotherapy.
MAb The MAbs used in this study were human milk fat globule 1 (HMFG1 and AUA1; Unipath, Bedford, UK, Ltd). HMFG1 is a mouse IgGI MAb that binds to a mucin molecule found on more than 90% of serous papillary ovarian carcinomas."27 28 The antibody AUA1 binds to a 35 kd cell-surface antigen found on the colonic cancer cell line LoVo, but also expressed by 75% of ovarian cancers. 29'3 HMFG I was used alone in 22 patients, AUA1 in one patient, and a cocktail of both antibodies in two patients. Before patients were considered suitable for RIT, the original tumor histology was examined for positive immunoperoxidase staining by these antibodies. Both these antibodies can be used to identify antigens in tissue that has been formalin fixed, and preserved in wax; this was important as fresh tissue is not always available. Suitable patients had more than 50% of their tumor cells (from at least 10 random high-power fields) express antigens that bound to either HMFGI or AUAI. Patients received between 14.6 and 34.6 mg of labeled antibody, with a mean of 18 mg (Table 1). Most patients received HMFGI, AUA1 alone was used in one patient whose tumor did not express HMFGI antigen, and AUAI and HMFGI were used together in two patients whose tumors strongly expressed both antigens.
Downloaded from ascopubs.org by 5.62.155.97 on February 10, 2017 from 005.062.155.097 Copyright © 2017 American Society of Clinical Oncology. All rights reserved.
1943
Y-90-LABELED ANTIBODY IN OVARIAN CANCER Table 1. Patient, Treatment, and Response Data in Patients Receiving IP Y-90 HMFG 1 Tumor Size in Centimeters
Amount of MAb (mg)
Yttrium-90 Activity (MCi)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
< 2 cm None seen < 2 cm < 2 cm < 2 cm None seen < 2 cm None seen > 2 cm Positive cytology None seen None seen None seen None seen None seen < 2 cm None seen Ascites < 2 cm None seen Noneseen
22 23 24
> 2 cm < 2 cm < 2 cm
25
< 2 cm
30 16.8 20 20 20 20 20 20 18 28 20 25 24 20 18 28* 15 23 16 18 18 17* 14.6 18.2 19 15.6* 23
5 16.4 12.5 15 15 15 15.1 16.9 20 6 15 17.6 17.7 16.8 18.2 18.4 21 25.2 20.3 19.6 11.3 11.3 18.2 20.6 6.2 6.1 20.6
Patient No.
Tumor Response Partial response Disease-free at 15 months Progressive disease Progressive disease Progressive disease Disease-free at 12 months Progressive disease Progressive disease Progressive disease Progressive disease Disease-free at 6 months Disease-free at 12 months Disease-free at 12 months Disease-free at 9 months Disease-free at 9 months Progressive disease Disease-free at 6 months Progressive disease Progressive disease Disease-free at 9 months Disease-free at 6 months Progressive disease Progressive disease Progressive disease Disease-free at 6 months
*AUA1 instead of HMFG1.
Antibody Labeling Y-90 (Unipath Ltd, United Kingdom) was supplied by Atomic Energy Research Establishment, Harwell, Berkshire, United Kingdom, from a strontium-90 generator. Strontium contamination accounted for less than 1 part per 105 to 10'. The yttrium was chelated to the antibody/DPTA complex as described by Hnatowich et al. 24 Free yttrium was removed by Sephadex G-50 (Pharmacia LKB, Biotechnology AB, Uppsala, Sweden) gel filtration using phosphate-buffered saline pH 7.4. Antibody immunoreactivity was tested by an enzymelinked immunoadsorbent assay (ELISA) method before and after radiolabeling, on microtiter plates coated with purified antigen and compared with underivatized antibody." No significant difference was seen between the two. The administered dose was measured in a SIEL isotope calibration chamber (SIEL Imaging EQ Ltd, Aldermaston, Berks, England) that had been calibrated with an yttrium source. Treatment Details Peritoneal dialysis catheters were inserted into the peritoneal cavity at open laparoscopy. Open laparoscopy also allowed the placement of thermoluminescent dosimetry (TLD) catheters (see below), and a visual assessment of disease volume including peritoneal lavage with 50 mL of 0.9% saline
for cytologic assessment. Minor adhesions particularly around the liver were noted in most patients, but a good view (all four quadrants of the peritoneal cavity) was obtained in all but one patient. This patient had many peritoneal adhesions and has not been included in this series. Two patients had small perforations of the bowel, which occurred at laparoscopy, and were immediately identified. These were sutured without further complication and the patients treated. The Y-90labeled antibody was infused into the peritoneal cavity with 1.5 L of 0.9% saline. Following the infusion, the peritoneal dialysis catheter was removed, and the patient's position altered every 20 minutes to encourage an even IP distribution of antibody. Patients were nursed in a radiation-controlled area for 5 days during which blood samples were taken at 12 hourly intervals for Y-90 activity, and urine collected to monitor Y-90 excretion. During this study it became apparent that bone concentration of Y-90 following antibody catabolism was contributing to myelosuppression. In an attempt to reduce the uptake of Y-90 by bone, the last seven patients received IV EDTA (Sinclair Pharmaceuticals Ltd, Godalming, United Kingdom) after the IP infusion of Y-90-labeled antibody. EDTA was infused IV (40 mg/m 2 over 4 hours) at 14, 26, 38, 50, 62, and 74 hours after the IP administration of Y-90-labeled antibody. EDTA infusions were accompanied by IV fluids to ensure a daily urine output of a least 2 L.
Downloaded from ascopubs.org by 5.62.155.97 on February 10, 2017 from 005.062.155.097 Copyright © 2017 American Society of Clinical Oncology. All rights reserved.
1944
STEWART ET AL
Pharmacokineticsand Dosimetry In 20 patients the blood and urine Y-90 activities were measured in a scintillation well counter, comparing the "bremsstrahlung" x-rays with those of known Y-90 standards in identical containers. The Y-90 activity in each patient's circulation was extrapolated from that of the measured blood samples by estimating each patient's blood volume from their surface area.3 For each patient, a plot of whole blood Y-90 activity against time (100 hours after RIT) was constructed. The area under this curve (AUC) in microcurie-hours of Y-90 activity, was used to estimate the radiation dose the bone marrow received from Y-90-labeled antibody in the marrow circulation according to the Medical Internal Radia32 Marrow is extremely tion Dose (MIRD) formulation. vascular and macromolecules rapidly reach equilibrium with 34 33 the blood. Active marrow constitutes 2.2% of body weight, that is, 25% to 31% of the blood weight, and for these calculations, the Y-90 activity actually in the marrow was assumed to be 20% of the integrated blood activity. The estimated bone marrow dose in cGy was calculated using A x S where A is the cumulative Y-90 activity (in marrow) expressed as microcurie hours and S is the S value for marrow 32 as a source and target organ. Y-90 activities were corrected for radioactive decay when expressing the pharmacokinetics of Y-90-labeled antibody in blood and urine to facilitate comparison with other radiolabels. The fraction of Y-90 activity bound to protein in the blood was measured in six patients by Sephadex gel filtration of serum at 14, 38, 62, 87, and 110 hours. The pharmacokinetics of the patient with ascites (patient no. 18) was not included in this study as patients with ascites absorb less radiolabeled antibody from the peritoneal cavity (probably due to lymphatic obstruction). This totally changes the dosimetry to the bone marrow and peritoneal serosa. In 10 patients, the radiation dose to the peritoneal serosa from nontargeted Y-90-labeled antibody was measured by lithium fluoride (LiF) TLD. We were unable to biopsy tumor deposits after treatment but would assume that they received a high radiation dose due to antibody targeting. The TLD measurements from two ovarian cancer patients who received IP Y-90 silicate colloid (Amersham International Plc, Amersham, United Kingdom) are also included for comparison. Both patients had diffuse small peritoneal tumor nodules following chemotherapy and received 50 mCi of Y-90 silicalte colloid. For each patient, 20 to 35 LiF rods each 6 x 1 mm (TLD-100) (Harshaw/Filtrol Partnership, OH) were placed in a plastic tube of wall thickness 0.1 mm. The tube was heat sealed and sterilized before being inserted into the peritoneal cavity at laparoscopy. The TLD catheter remained in situ for 110 hours before being removed, and the light output of each rod measured in a 654A Toledo TLD reader (Vinten Instruments Ltd, Surrey, United Kingdom). The TLD rods were calibrated by immersing representative samples in a solution containing a known activity of Y-90 for time intervals. This calibration closely agreed with independent calibrations using known radiation doses from 4 MeV electrons delivered by a linear accelerator. Response Laparoscopy was used to assess tumor response 8 to 12 weeks after treatment, unless patients had already developed progressive disease clinically. Pre- and posttreatment lap-
aroscopies were all performed by one of the authors (V.H.) to facilitate the comparison of tumor deposits following treatment. Responses were divided into complete response (CR), the disappearance of all tumor, and partial response (PR), a 50% reduction in tumor volume. Otherwise, disease was categorized as progressive disease (PD) as it was difficult to accurately determine minimal regression or stable disease at laparoscopy.
Toxicity Patients were reviewed weekly for at least 6 weeks after treatment to assess toxicity. Hematologic and biochemical parameters were assessed, along with liver function tests and antibody titers to the mouse MAb (human antimouse antibody [HAMA]). Blood counts were graded into five grades according to the World Health Organization (WHO) classification" (Table 2). Bone marrow suppression was given an arbitrary score of the sum of the WHO grades for neutropenia and thrombocytopenia.
Statistics A nonparametric statistical analysis, the Mann-Whitney U test, was used to test the significance between different groups of pharmacokinetic data.
RESULTS
Pharmacokinetics Y-90 activity was detected in patients' circulation following the IP administration of Y-90labeled antibody (Fig 1). Peak blood activity was observed at 40 hours with a mean of 21.3% (range, 13.9% to 29%; N = 21 patients) of the injected Y-90 activity in the circulation. Sephadex G-50 gel filtration of serum from six patients indicated that a mean of 97.4% (range, 99.7% to 93.2%; N = 32 measurements) of the Y-90 activity was bound to protein, and affinity chromatography with rabbit antimouse Ig, confirmed this protein to be murine antibody. Following peak blood radioactivity, Y-90-labeled antibody was cleared exponentially from the circulation with a mean biologic half-life of 50 hours (range, 30 to 84 hours; N = 21). Patients who received an IV EDTA infusion appeared to have slightly lower circulating Y-90 activity (Fig 1). A MannWhitney analysis of the AUCs (percentage of Table 2. WHO Grades for Neutropenia and Thrombocytopenia WHO Grade Count
Platelet Count IO0/L
Neutrophil 106/L
0
>100
>4
1 2 3 4
75-99 50-74 25-49 < 25
3-3.9 2-2.9 1-1.9 < 1
Downloaded from ascopubs.org by 5.62.155.97 on February 10, 2017 from 005.062.155.097 Copyright © 2017 American Society of Clinical Oncology. All rights reserved.
1945
Y-90-LABELED ANTIBODY IN OVARIAN CANCER
0
10.3 cGy to 46.2 cGy following the administration of 5 to 19.2 mCi of Y-90-labeled antibody, respectively (Fig 3).
20
RadiationDose to Peritoneum 10 II
z
Ca
a, 0 O
0
-
0
20
40
60
80
100
Hours after IP infusion Fig 1. Blood Y-90 expressed as percentage of injected activity (coarrected for radioactive decay). (0) All patients; M with IV EDTTA; (A)without ETDA.
injected dose x time) between patients receiving and not receiving EDTA confirmed this tendency, although this was not statistically significant (Mann-Whitney U = 30, .1
