BK-UM in patients with recurrent ovarian cancer or peritoneal cancer: a first-in-human phase-I study

This clinical trial was undertaken as an open-label, phase-I dose-escalation study, and was performed as a prospective investigator-initiated clinical trial. The study was conducted at Fukuoka University Hospital (Fukuoka, Japan) in accordance with the principles of the Declaration of Helsinki and the International Conference on Harmonization’s Good Clinical Practice Guidelines. The study protocol was approved by the Institutional Review Board of Fukuoka University Hospital.

Study-inclusion criteria were:(i) EOC or primary PC confirmed by histology; (ii) recurrent OC or PC within 6 months after completion of a primary treatment containing platinum and a taxane (including patients who had received second- or subsequent-line chemotherapy after recurrence following primary treatment containing platinum and a taxane); (iii) performance status 0 or 1 according to the Eastern Cooperative Oncology Group classification; (iv) evidence of adequate liver, kidney, and bone marrow functions (absolute white blood cell count >3000/μL, or neutrophil count ≥1000/μL, platelet count ≥100,000/μL, hemoglobin ≥8.0 g/dL, aspartate aminotransferase ≤2.5-fold the upper limit of normal, alanine transaminase ≤2.5-fold the upper limit of normal, serum total bilirubin ≤1.5 mg/dL, serum creatinine ≤1.5 mg/mL); (v) detectable levels of HB-EGF in serum or peritoneal fluid; (vi) diphtheria antibody titer <0.1 IU/mL; and (vii) practicality of placing a port in the abdomen.

All subjects underwent electrocardiography to confirm the absence of abnormalities requiring treatment, and sensory and motor nerve-conduction studies to evaluate peripheral neuropathy.

Exclusion criteria were: (i) history of cardiac disease ≥ III according to the New York State Heart Association classification; (ii) <50% left ventricular ejection fraction by echocardiography; (iii) myocardial infarction within 6 months of study enrollment; (iv) uncompensated liver cirrhosis; (v) severe lung disease necessitating oxygen inhalation; (vi) psychotic disorders; (vii) uncontrolled diabetes mellitus; (viii) ileus or subileus; (ix) uncontrolled infectious disease; (x) peripheral neuropathy of grade ≥2; (xi) pregnancy or breastfeeding; (xii) life expectancy <3 months; (xiii) receipt of an investigational agent within 28 days before study enrollment; and (xiv) history of administration of antiserum.

Concurrent investigational or antineoplastic agents were not permitted during the study.

This was a dose-escalation study with a 3 + 3 trial design at each dose to determine the maximum-tolerated dose (MTD) and recommended dose. BK-UM was administered intraperitoneally at doses of 1.0, 2.0, 3.3, and 5.0 mg/m², 5 days a week for 2 weeks, based on the results of a pre-clinical study [21]. An anti-histamine was administered as premedication before BK-UM injection. Dose escalation of BK-UM was investigated by the Data and Safety Monitoring Committee (DSMC). Treatment of the first patient was finished completely, and the safety of BK-UM was then reviewed by the DSMC. If no dose-limiting toxicity (DLT) was observed in three patients at a given dose, the next three patients were treated with the next-higher dose. If DLT was experienced by one or two of the three patients at any dose, three additional patients were treated with the same dose. If two or fewer of six patients treated with a given dose exhibited DLT, this dose was considered to exceed the MTD and dose escalation was halted. The recommended phase-II dose was defined as one dose level lower than the MTD. Patients who progressed after showing a response to BK-UM were not allowed to be re-treated with BK-UM. If more than two patients withdrew from the present study, safety was evaluated by the DSMC. Conventional chemotherapy was administered in patients who requested it after the observation period of the trial, for as long as there was a diagnosis of progressive disease, or for six courses in patients with stable disease (SD), partial response (PR), or complete response.

All AEs were graded according to the Common Terminology Criteria for Adverse Events v3.0 set by the National Cancer Institute. DLT was defined as an AE or laboratory abnormality that occurred 6 weeks after the first infusion of BK-UM. A DLT was judged to be related to BK-UM if it met any of the following criteria: hematologic toxicity grade ≥4; gastrointestinal disorder possibly due to peritonitis carcinomatosa grade ≥4; or non-hematologic toxicity grade ≥3. Safety data were evaluated by the DSMC at all doses.

Responses were evaluated 6 weeks after the first infusion of BK-UM. Recurrent lesions were evaluated by computed tomography before infusion of BK-UM, to provide baseline images. Clinical evaluation of response was estimated using baseline computed tomography images and findings 6 weeks after the first infusion of BK-UM, according to Response Evaluation Criteria in Solid Tumors (RECIST) v1.0 guidelines. The interval for overall survival was defined as the period from the day of the first infusion of BK-UM to the day on which death occurred. Some patients were discharged from Fukuoka University Hospital after the end of this clinical trial and treated at other hospitals, and the dates of death for these patients were recorded using information acquired from those hospitals.

Blood and abdominal fluid were withdrawn from all patients into anticoagulant-excluded tubes before and after infusion of BK-UM. HB-EGF concentrations in serum and abdominal fluid were determined by a modified enzyme assay [22] using a sandwich ELISA (DuoSet; R&D Systems, Minneapolis, MN, USA).

This trial was conducted at 12/10/2007. Eleven of 50 patients with recurrent cancer were enrolled, including 10 with OC and one with primary PC (Table 1). The remaining 39 patients were not eligible for the following reasons: 12 patients had diphtheria antibody levels >0.1 IU/mL; 21 and five patients had performance statuses of 2 or 3, respectively; and one patient recurred more than 6 months after primary treatment containing platinum and a taxane. Among the patients who received BK-UM at 1.0 mg/m² (level 1 dose), one patient had leptomeningeal disease previously treated using a γ-knife, but had been in a stable condition for 4 months. Four patients (numbers 1–4) were enrolled at 1.0 mg/m² BK-UM (dose level 1) because one patient who lived in Tokyo wanted to return to Tokyo, and withdrew their consent soon after BK-UM treatment.

Eight patients completed the study according to the protocol, one patient withdrew their consent as noted above, and two patients dropped out of the trial because of DLTs. All 11 enrolled patients were evaluated for safety and efficacy on an intent-to-treat basis.

All AEs of grade ≥2 are listed in Table 2. All patients experienced at least one AE. At BK-UM doses of 1.0 and 2.0 mg/m² (dose levels 1 and 2), all AEs were considered unlikely to have a causal association with BK-UM. Grade 3 AEs such as ileus, abdominal fullness, and anemia were observed in one patient at 2.0 mg/m² BK-UM (dose level 2). Most patients had grade 1 fever between days 1 and 3 of BK-UM treatment, but neither the frequency nor severity of these AEs increased with dose escalation. BK-UM was thus generally considered to be well-tolerated at doses of 1.0 and 2.0 mg/m². However, both patients treated at 3.0 mg/m² BK-UM (dose level 3) developed grade 3 hypotension on day 8 of treatment, which was defined as a DLT. This AE manifested as nausea, abdominal pain, and transient hypotension, accompanied by irritation of the peritoneum, fever, and elevated C-reactive protein levels. Complete recovery from all AEs was observed within 1 week in both patients. All other AEs observed at dose level 3 were grade ≤2. No severe AEs (grades 4 or 5), including severe cardiotoxicity- or neurotoxicity-related DLTs, were found in any patient at any dose level.

No DLT was observed at dose levels 1 and 2, but two patients at dose level 3 showed grade 3 hypotension 8 days after the first infusion. The MTD was therefore judged to be at dose level 3 (3.0 mg/m²), and the recommended dose was determined to be 2.0 mg/m².

The plasma concentration of BK-UM after intraperitoneal administration was measured 15 times per course in each patient. At 1.0 mg/m² BK-UM (dose level 1), plasma BK-UM was only detected in three of 60 samples from four patients. BK-UM plasma levels were detected in nine of 45 samples from three patients at 2.0 mg/m² (level 2) and 11 of 51 samples from four patients at 3.0 mg/m² (level 3). The plasma concentration of BK-UM was unmeasurable throughout the treatment with BK-UM in five patients, while BK-UM was only sporadically detected in plasma in the remaining six patients. These results suggested that intraperitoneal delivery of BK-UM did not result in clinically relevant plasma exposure (Additional file 1: Table S1).

BK-UM treatment resulted in reductions in HB-EGF serum concentrations in five patients, in abdominal fluid in four patients, and in abdominal fluid and serum in four patients (Table 3). Patients 2, 8, and 11 were not included in this analysis because HB-EGF concentrations were not measured on the scheduled day after BK-UM treatment in these patients. The present results suggested that BK-UM reduced HB-EGF concentrations in abdominal fluid or serum if the HB-EGF concentration was ≥125 pg/mL. Serum levels of cancer antigen-125 also decreased in two of 11 patients. DT antibody levels were increased in all patients after BK-UM treatment. One of the 11 patients achieved PR (Table 3), five patients showed SD, and the remaining five patients showed progressive disease. In addition to the abdominal cavity, patients 4, 6, and 9 had metastatic lesions in the brain, liver, and lungs, respectively (though patient number 4 had a history of leptomeningeal disease previously treated by γ-knife, and had been in a stable condition for 4 months). The metastatic lesions in the abdominal cavity in these three patients were markedly reduced after BK-UM treatment, even though the extra-abdominal lesions had progressed or were stable. At least three patients received intraperitoneal administration of BK-UM 1 mg/m² or 2 mg/m² for 2 weeks. Only patients 1 and 4 (level 1) received two courses of intraperitoneal BK-UM (1 mg/m²), and responses in these patients were evaluated at week 8 after the start of the first course of BK-UM, compared with evaluation at week 6 in the other patients who only received one course of intraperitoneal BK-UM. The benefit of intraperitoneal administration of BK-UM thus lasted up to 6 weeks in patients 3, 5, 10, and 11, and 8 weeks in patients 1 and 4. Conventional chemotherapy was started at week 9 in patients 1 and 4, and week 7 in patients 3, 7, 8, 10, and 11. Patients 2, 5, 6, and 9 requested no further therapy. Five of the seven patients who received further conventional chemotherapy exhibited overall survival beyond 14 months (Table 4). Three patients (1, 3, and 11) showed no evidence of disease following BK-UM treatment and subsequent therapy, and one patient (11) remained free of disease.