Phase I/IIa study of combination chemotherapy with CKD-602 and cisplatin in patients with recurrent epithelial ovarian cancer

Synergism of AZD6738, an ATR Inhibitor, in Combination with Belotecan, a Camptothecin Analogue, in Chemotherapy-Resistant Ovarian Cancer

Epithelial ovarian cancer remains the leading cause of mortality among all gynecologic malignancies owing to recurrence and ultimate development of chemotherapy resistance in the majority of patients. In the chemotherapy-resistant ovarian cancer preclinical model, we investigated whether AZD6738 (an ataxia telangiectasia and Rad3-related (ATR) inhibitor) could synergize with belotecan (a camptothecin analog and topoisomerase I inhibitor). In vitro, both chemotherapy-resistant and chemotherapy-sensitive ovarian cancer cell lines showed synergistic anti-proliferative activity with a combination treatment of belotecan and AZD6738. The combination also demonstrated synergistic tumor inhibition in mice with a chemotherapy-resistant cell line xenograft. Mechanistically, belotecan, a DNA-damaging agent, increased phospho-ATR (pATR) and phospho-Chk1 (pChk1) in consecutive order, indicating the activation of the DNA repair system. This consequently induced G2/M arrest in the cell cycle analysis. However, when AZD6738 was added to belotecan, pATR and pChk1 induced by belotecan alone were suppressed again. A cell cycle analysis in betotecan showed a sub-G1 increase as well as a G2/M decrease, representing the release of G2/M arrest and the induction of apoptosis. In ascites-derived primary cancer cells from both chemotherapy-sensitive and -resistant ovarian cancer patients, this combination was also synergistic, providing further support for our hypothesis. The combined administration of ATR inhibitor and belotecan proved to be synergistic in our preclinical model. This combination warrants further investigation in a clinical trial, with a particular aim of overcoming chemotherapy resistance in ovarian cancer.

A multicentre, randomised, open-label, parallel-group Phase 2b study of belotecan versus topotecan for recurrent ovarian cancer

BACKGROUND

This Phase 2b study compared the efficacy and toxicity of belotecan and topotecan in recurrent ovarian cancer.

METHODS

Patients with platinum-sensitive recurrent or platinum-resistant recurrent ovarian cancer (PRROC) were randomised 1:1 to receive belotecan 0.5 mg/m2 or topotecan 1.5 mg/m2 for five consecutive days every 3 weeks. The primary endpoint was overall response rate (ORR); secondary endpoints were progression-free survival (PFS), overall survival (OS), and toxicity.

RESULTS

A total of 140 (belotecan, n = 71; topotecan, n = 69) and 130 patients (belotecan, n = 66; topotecan, n = 64) were included in the intention-to-treat (ITT) and per-protocol (PP) populations. ORR did not differ significantly between the belotecan and topotecan groups (ITT, 29.6% versus 26.1%; PP, 30.3% versus 25%). Although PFS did not differ between the groups, belotecan was associated with improved OS compared with topotecan in the PP population (39.7 versus 26.6 months; P = 0.034). In particular, belotecan showed longer OS in PRROC and non-high-grade serous carcinoma (non-HGSC; PP, adjusted hazard ratios, 0.499 and 0.187; 95% confidence intervals 0.255-0.977 and 0.039-0.895). Furthermore, there were no differences in toxicities between the two groups.

CONCLUSIONS

Belotecan was not inferior to topotecan in terms of overall response for recurrent ovarian cancer.

CLINICAL TRIAL REGISTRATION

NCT01630018.

Durable response after just one cycle of belotecan-based chemotherapy in a patient with relapsed primary peritoneal serous carcinoma

The efficacy of second-line chemotherapy for relapsed primary peritoneal serous carcinoma has been numerously reported, but reports on durable response after second-line therapy have been rare. We report the case of a 66-year-old woman with relapsed primary peritoneal serous carcinoma who showed durable response after just one cycle of second-line belotecan-based therapy. The response might be a complete pathologic remission. Considering the fact that our patient suffered from neutropenic sepsis during her treatment, we concluded that belotecan-based chemotherapy could be a good option for second-line chemotherapy in some selected patients, so patient selection should be carefully performed due to the toxicity of belotecan.

Dose-finding design driven by efficacy in onco-hematology phase I/II trials

We present an adaptive model-based procedure for dose finding in phase I/II clinical trials when both efficacy and toxicity responses are available. In this setting, previous designs aimed at identifying the maximum tolerated dose as a surrogate for efficacy or the most successful dose, defined as the dose with the highest probability of efficacy without toxicity. Rather than using this definition of success, we propose considering all responses conditionally on the probability that dose-limiting toxicity is under a pre-specified threshold. The presented approach uses a joint model for the probability of an efficacy response and toxicity, and is evaluated through simulations. A retrospective application to a Phase I trial conducted in chronic lymphocytic leukemia is presented.

Phase II study of belotecan, a camptothecin analogue, in combination with carboplatin for the treatment of recurrent ovarian cancer

BACKGROUND

Belotecan (CKD602; Camtobell, Chong Keun Dang Corp., Seoul, Korea) is a recently developed camptothecin derivative with antitumor properties. This phase II study was designed to evaluate the toxicity and efficacy of belotecan combined with carboplatin in patients with recurrent epithelial ovarian cancer (EOC).

METHODS

Thirty-eight patients with recurrent EOC were treated with belotecan 0.3 mg/m(2) /day (days 1-5) and carboplatin AUC 5 (day 5) every 3 weeks for 6 cycles. The primary objective was to determine the response rate as defined by Response Evaluation Criteria in Solid Tumors and CA-125 response. Other end points included toxicities and progression-free survival (PFS).

RESULTS

All 38 patients were assessed for toxicity, and 35 patients were assessed for response. The overall response rate was 57.1%; there were 7 complete responses (20.0%), 13 partial responses (37.1%), 6 patients with stable disease (17.1%), and 9 patients with progressive disease (25.7%). Grades 3 and 4 hematologic toxicities included neutropenia (28.8%), thrombocytopenia (19.8%), and anemia (14.4%), and there were 2 episodes of febrile neutropenia. Median PFS was 7 months, with a median follow-up of 12 months.

CONCLUSIONS

The newly developed topoisomerase I inhibitor belotecan (CKD-602) combined with carboplatin is a well-tolerated regimen with activity in recurrent EOC. Further testing of this regimen is warranted to further characterize efficacy and indications for use.

Comparison of the efficacy between topotecan- and belotecan-, a new camptothecin analog, based chemotherapies for recurrent epithelial ovarian cancer: a single institutional experience

AIM

To compare the efficacy and toxicity between topotecan- and belotecan-based chemotherapies in recurrent epithelial ovarian cancer (EOC).

METHODS

The clinical data of 80 patients treated with topotecan- (n = 45) or belotecan- (n = 35) based chemotherapy as at least a second-line chemotherapy were reviewed retrospectively between July 2001 and December 2007. Response was evaluated using the Response Evaluation Criteria in Solid Tumours (RECIST) and serum CA-125 levels. Hematological toxicity was examined according to the National Cancer Institute Common Toxicity Criteria (NCI-CTC) version 2.0. Time to progressive disease (TTPD), chemotherapy-specific survival (CSS) and overall survival (OS) according to the 2 chemotherapies were evaluated by the Kaplan-Meier analysis with the log-rank test.

RESULTS

Overall response rate (ORR) was 24.4% in patients treated with topotecan-based chemotherapy, while it was 45.7% in those treated with belotecan-based chemotherapy (P = 0.046). Moreover, ORR was higher in platinum-sensitive patients treated with belotecan-based chemotherapy (58.8%) than those treated with topotecan-based chemotherapy (22.2%) (P = 0.041) although it was not significantly different in platinum-resistant patients (P = 0.471). Grade 3 or 4 anemia, neutropenia and thrombocytopenia developed in 14.8% vs 3.6%, 43.1% vs 55.6%, and 20.0% vs 12.8% of cycles in topotecan- and belotecan-based chemotherapies, respectively (P < 0.05). There were no significant difference in survival between the 2 chemotherapies.

CONCLUSIONS

In our experience, belotecan-based chemotherapy seemed to be efficient with acceptable toxicity, compared to topotecan-based chemotherapy in recurrent EOC. However, randomized controlled trials are required for the comparison of the efficacy and toxicity between topotecan- and belotecan-based chemotherapies in recurrent EOC.