A multicenter phase II study of belotecan, new camptothecin analogue, in patients with previously untreated extensive stage disease small cell lung cancer

Natural product inspired leads in the discovery of anticancer agents: an update

Natural products have emerged as major leads for the discovery and development of new anti-cancer drugs. The plant-derived anti-cancer drugs account for approximately 60% and the quest for new anti-cancer agents is in progress. Anti-cancer leads have been isolated from plants, animals, marine organisms, and microorganisms from time immemorial. The process of semisynthetic modifications of the parent lead has led to the generation of new anti-cancer agents with improved therapeutic efficacy and minimal side effects. The various chemo-informatics tools, bioinformatics, high-throughput screening, and combinatorial synthesis are able to deliver the new natural product lead molecules. Plant-derived anticancer agents in either late preclinical development or early clinical trials include taxol, vincristine, vinblastine, topotecan, irinotecan, etoposide, paclitaxel, and docetaxel. Similarly, anti-cancer agents from microbial sources include dactinomycin, bleomycin, mitomycin C, and doxorubicin. In this review, we highlighted the importance of natural products leads in the discovery and development of novel anti-cancer agents. The semisynthetic modifications of the parent lead to the new anti-cancer agent are also presented. Further, the leads in the preclinical settings with the potential to become effective anticancer agents are also reviewed.Communicated by Ramaswamy H. Sarma.

Synthesis and biological evaluation of 5-aminoethyl benzophenanthridone derivatives as DNA topoisomerase IB inhibitors

DNA topoisomerase IB (TOP1) regulates DNA topological structure in many cellular metabolic processes and is a validated target for development of antitumor agents. Our previous study revealed that the benzophenanthridone scaffold is a novel chemotype for the discovery of TOP1 inhibitors. In this work, a series of novel 5-aminoethyl substituted benzophenanthridone derivatives have been synthesized and evaluated for TOP1 inhibition and cytotoxicity. Compound 12 exhibits the most potent TOP1 inhibition (+++) and cytotoxicity in human cancer cell lines with GI₅₀ values at nanomolar concentration range. 12 induces the cellular TOP1cc formation and DNA damage, resulting in HCT116 cell apoptosis. The pharmacokinetics, acute toxicity and antitumor efficiency in vivo of 12 were also studied.

Adverse drug reactions of anticancer drugs derived from natural sources

Cancer, a life threatening disease adversely affects huge population worldwide. Naturally derived drug discovery has emerged as a potential pathway in search of anticancers. Natural products-based drugs are generally considered safe, compared to their synthetic counterparts. A systematic review on adverse drugs reactions (ADRs) of the anticancer natural products has not been performed till date. We reviewed anticancer drugs, derived from plants, microbes and marine sources with their mechanistic action and reported ADRs. PubMed, ScienceDirect and Scopus were searched through Boolean information retrieval method using keywords "natural products", "cancer", "herbal", "marine drugs" and "adverse drug reaction". We documented ADRs of natural products based anticancer agents, mechanisms of action and chemical structures. It was observed that majority of the natural products based anticancer drugs possess ample adverse effects, dominantly hematological toxicities, alopecia, neurotoxicity and cardiotoxicity. These findings deviate from the preconceived notion about safer nature of herbal drugs. We also came across some anti-cancer natural products with less/no reported adverse events like Cabazitaxel and Arglabin. Comprehensive pharmacovigilance studies are needed to report ADRs and thereby predicting safety of anti-cancer drugs, either originated from natural sources or chemically synthesized.

Topoisomerase 1B poisons: Over a half-century of drug leads, clinical candidates, and serendipitous discoveries

Topoisomerases are DNA processing enzymes that relieve supercoiling (torsional strain) in DNA, are necessary for normal cellular division, and act by nicking (and then religating) DNA strands. Type 1B topoisomerase (Top1) is overexpressed in certain tumors, and the enzyme has been extensively investigated as a target for cancer chemotherapy. Various chemical agents can act as "poisons" of the enzyme's religation step, leading to Top1-DNA lesions, DNA breakage, and eventual cellular death. In this review, agents that poison Top1 (and have thus been investigated for their anticancer properties) are surveyed, including natural products (such as camptothecins and indolocarbazoles), semisynthetic camptothecin and luotonin derivatives, and synthetic compounds (such as benzonaphthyridines, aromathecins, and indenoisoquinolines), as well as targeted therapies and conjugates. Top1 has also been investigated as a therapeutic target in certain viral and parasitic infections, as well as autoimmune, inflammatory, and neurological disorders, and a summary of literature describing alternative indications is also provided. This review should provide both a reference for the medicinal chemist and potentially offer clues to aid in the development of new Top1 poisons.

Lesser Toxicities of Belotecan in Patients with Small Cell Lung Cancer: A Retrospective Single-Center Study of Camptothecin Analogs

Purpose. Topotecan and belotecan are camptothecin derivatives that are used to treat small cell lung cancer (SCLC). This study compared the toxicities and efficacies of belotecan and topotecan monotherapies in patients with SCLC. Methods. We retrospectively reviewed data from 94 patients with SCLC (with or without prior chemotherapy) who were treated using belotecan monotherapy (n = 59, 188 cycles) or topotecan monotherapy (n = 35, 65 cycles) between September 2003 and December 2011. Results. Thrombocytopenia occurred during 42% and 61.5% of the belotecan and topotecan cycles, respectively (p = 0.007). Significant differences between belotecan and topotecan were also observed for grade 4/5 lung infection (3.2% versus 10.8%, resp.; p = 0.003), all-grade headache (3.2% versus 10.8%, resp.; p = 0.017), and grade 4/5 increased liver enzymes (0.5% versus 4.6%, resp.; p = 0.023). The median TTPDs, CSSs, and OSs were 14 months and 11.6 months (p = 0.646), 10 months and 7 months (p = 0.179), and 34.5 months and 21.4 months (p = 0.914) after belotecan and topotecan monotherapy, respectively. Conclusions. Belotecan monotherapy may be safer than topotecan monotherapy in SCLC patients. And in terms of efficacy, belotecan could be comparable to topotecan monotherapy.

Belotecan/cisplatin versus etoposide/cisplatin in previously untreated patients with extensive-stage small cell lung carcinoma: a multi-center randomized phase III trial

Background

No novel chemotherapeutic combinations have demonstrated superior efficacy to etoposide/cisplatin (EP), a standard treatment regimen for extensive-stage small cell lung carcinoma (ES-SCLC) over the past decade. We aimed to compare the efficacy and safety of belotecan/cisplatin (BP) and EP regimens in chemotherapy- and radiotherapy-naïve patients with previously untreated ES-SCLC.

Methods

We conducted a multi-center, randomized, open-label, parallel-group, phase III clinical study. A total of 157 patients were recruited at 14 centers with 147 patients meeting the inclusion/exclusion criteria and randomized to either BP (n = 71) or EP (n = 76) treatment arms. A non-inferior response rate (RR) in the BP arm, analyzed by intent-to-treat analysis according to Response Evaluation Criteria in Solid Tumors version 1.0 criteria, was used as the primary endpoint. The secondary endpoints were progression-free survival (PFS) and overall survival (OS).

Results

In the BP arm, one patient had a complete response, 41 had a partial response (PR), and 17 had stable disease (SD). In the EP arm, 35 patients had PR and 28 had SD. The RR in the BP arm was non-inferior to the EP regimen in patients with ES-SCLC (BP: 59.2 %, EP: 46.1 %, difference: 13.1 %, 90 % two-sided confidence interval: -0.3–26.5, meeting the predefined non-inferiority criterion of -15.0 %). No significant differences in OS or PFS were observed between the treatment arms. Hematologic toxicities, including grade 3/4 anemia and thrombocytopenia, were significantly more prevalent in the BP arm than the EP arm.

Conclusions

The RR to the BP regimen was non-inferior to the EP regimen in chemotherapy- and radiotherapy-naïve patients with previously untreated ES-SCLC. Hematologic toxicities were significantly more prevalent in the BP group, indicating that BP should be used with care, particularly in patients with a poor performance status. Further studies assessing PFS and OS are required to validate the superiority of the BP regimen.

Trial registration

ClinicalTrials.gov identifier NCT00826644. Date of Registration: January 21, 2009.

Chemotherapy advances in small-cell lung cancer

Although chemotherapeutic advances have recently been heralded in lung adenocarcinomas, such success with small-cell lung cancer (SCLC) has been ominously absent. Indeed, the dismal outlook of this disease is exemplified by the failure of any significant advances in first line therapy since the introduction of the current standard platinum-etoposide doublet over 30 years ago. Moreover, such sluggish progress is compounded by the dearth of FDA-approved agents for patients with relapsed disease. However, over the past decade, novel formulations of drug classes commonly used in SCLC (e.g. topoisomerase inhibitors, anthracyclines, alkylating and platinum agents) are emerging as potential alternatives that could effectively add to the armamentarium of agents currently at our disposal. This review is introduced with an overview on the historical development of chemotherapeutic regimens used in this disease and followed by the recent encouraging advances witnessed in clinical trials with drugs such as amrubicin and belotecan which are forging new horizons for future treatment algorithms.

A multicenter phase II study of belotecan, a new camptothecin analogue, in elderly patients with previously untreated, extensive-stage small cell lung cancer

PURPOSE

Belotecan is a new camptothecin analogue and a potent topoisomerase I inhibitor. The aim of this phase II study was to investigate the efficacy and toxicity of belotecan in previously untreated elderly patients with small cell lung cancer (SCLC).

METHODS

A total of 26 patients, aged ≥65 years, with previously untreated, extensive-stage SCLC were enrolled in the study. Belotecan was administered by daily intravenous infusion at 0.5 mg/m(2)/day for 5 consecutive days every 3 weeks.

RESULTS

The overall response rate and disease control rate of chemotherapy on an intention-to-treat basis were 35 and 54 %, respectively. The median overall survival was 6.4 months, and the median time to progression was 2.8 months. The most common toxicity was hematologic. Grade 3 or 4 neutropenia occurred in 80.8 % of patients, and grade 3 or 4 thrombocytopenia in 15.3 %. Non-hematologic toxic effects of grade 3 or 4 were uncommon.

CONCLUSION

Belotecan had modest efficacy and well-tolerated toxicity in previously untreated, elderly SCLC patients. Single belotecan could be a promising treatment option, considering its lower toxicity in elderly patients who are unsuitable candidates for platinum plus etoposide chemotherapy.

Efficacy and toxicity of belotecan for relapsed or refractory small cell lung cancer patients

INTRODUCTION

Belotecan (Camtobell, CKD602) is a new camptothecin-derivative antitumor agent that belongs to the topoisomerase inhibitors. The aim of this study was to evaluate the efficacy and safety of belotecan monotherapy as a second-line therapy in patients with relapsed or refractory small cell lung cancer (SCLC).

METHODS

Between June 2008 and August 2011, a total of 50 patients with relapsed or refractory SCLC were treated with belotecan 0.5 mg/m for 5 consecutive days, every 3 weeks. We evaluated the overall response rate (ORR), the progression-free survival (PFS), and the overall survival (OS), and toxicity according to sensitivity to initial chemotherapy.

RESULTS

The median age was 66 years (range, 43-84 years) and Eastern Cooperative Oncology Group performance was 0 or 1 in 34 patients (68%) and 2 in 16 patients (32%). Twenty patients (40%) had sensitive relapse and 30 patients (60%) had refractory disease. The ORR, PFS, and OS for sensitive patients were 20% (95% confidence interval [CI], 8-40), 2.8 months (95% CI, 0.53-5.06), and 6.5 months (95% CI, 1.58-11.42), respectively. In the refractory group, the ORR, PFS, and OS were 10% (95% CI, 1-21), 1.5 months (95% CI, 1.25-1.75), and 4.0 months (95% CI, 3.40-4.60), respectively. Most commonly reported grade-3 or -4 adverse events included neutropenia (54%), thrombocytopenia (38%), and anemia (32%).

CONCLUSION

Belotecan showed modest activity with an acceptable safety profile as a second-line therapy in patients with relapsed or refractory SCLC.

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.

A multicenter phase II study of belotecan, a new camptothecin analogue, as a second-line therapy in patients with small cell lung cancer

Belotecan (Camtobell, CKD602) is a new camptothecin derivative antitumor agent that belongs to the topoisomerase inhibitors. The aim of this phase II study was to evaluate the efficacy and safety of single agent belotecan as a second-line therapy in patients with small cell lung cancer (SCLC). Patients who were previously treated for SCLC were entered into the study. Belotecan was given by daily intravenous infusion for five consecutive days, every three weeks. Twenty-five patients were enrolled in this study. On an intention-to-treat basis, belotecan induced an overall response rate of 24%, a median overall survival of 9.9 months, a median time to progression of 2.2 months, and a 1-year survival rate of 38.3%. Grade 3/4 neutropenia developed in 88.0% of patients and grade 3/4 thrombocytopenia in 40.0%. Nonhematologic toxicity of grade 3 or 4 was low. The results suggest that belotecan is relatively active and well tolerated as a second-line agent in patients with SCLC.