Clinical Cancer Research. 2011 Jan 10. [Epub ahead of print] [Link]

Shapiro GI, Tibes R, Gordon MS, Wong BY, Eder JP, Borad MJ, Mendelson DS, Vogelzang NJ, Bastos BR, Weiss GJ, Fernandez C, Sutherland W, Sato H, Pierceall WE, Weaver D, Slough S, Wasserman E, Kufe DW, Von Hoff DD, Kawabe T, Sharma S.

Department of Medical Oncology, Dana Farber Cancer Institute.


Purpose: Two phase I dose-escalation studies were conducted to determine the maximum tolerated dose (MTD) and safety profile of the G2 checkpoint abrogator CBP501, as a single agent and in combination with cisplatin.

Experimental Design: Patients with advanced solid tumors were treated with CBP501 alone (D1/D8/D15, q4w, from 0.9 mg/m²), or with cisplatin (both on D1, q3w, from 3.6 mg/m² CBP501, 50 mg/m² cisplatin). Dose escalation proceeded if dose-limiting toxicity (DLT) was observed in ≤1 of 3-6 patients; CBP501 dose increments were implemented according to the incidence of toxicity. MTD was determined from DLTs occurring during the first two cycles.

Results: In the combination study, the DLT was a histamine-release syndrome (HRS) occurring 10-60 minutes after initiating infusion that was attenuated by prophylaxis comprising dexamethasone, diphenhydramine, ranitidine and loratadine. The MTD was 25 mg/m² CBP501 and 75 mg/m² cisplatin, with 2 patients at the highest dose (36.4 mg/m² CBP501, 75 mg/m² cisplatin) experiencing grade 3 HRS. The only DLT with monotherapy was transient G3 rise of troponin in one patient. Grade 3-4 treatment-related events were rare. Promising activity was observed with CBP501/cisplatin, mainly in ovarian and mesothelioma patients who had previously progressed on platinum-containing regimens. Among ovarian cancer patients, low expression of DNA repair proteins was associated with partial response or stable disease.

Conclusions: CBP501 is well tolerated in patients as monotherapy and with cisplatin. At the recommended phase 2 dose (RP2D) the combination is feasible and HRS manageable with prophylaxis. Evidence of anti-tumor activity was observed in platinum-resistant patients.