Camptothecin analogues/cisplatin: an effective treatment of advanced bladder cancer in a preclinical in vivo model system

GNRH family genes contributed to gender-specific disparity of bladder cancer prognosis through exerting opposite regulatory roles between males and females

PURPOSE

There is gender-specific disparity in bladder cancer (BlCa) prognosis. Female BlCa patients present with more advanced tumor and have higher risks of disease recurrence, progression, and mortality than males. Since gonadotropin-releasing hormone (GNRH) family genes were critical genes in gender-related biological activity and could be detected in BlCa specimens, this study aimed to explore potential roles of GNRH1 and GNRHR in gender disparity of BlCa.

METHODS

RNA-sequencing data from The Cancer Genome Atlas Bladder Urothelial Carcinoma dataset, IMvigor210 immunotherapy cohort and Cancer Cell Line Encyclopedia database were used to compare potential roles of GNRH1 and GNRHR in males and females, respectively. Gene set enrichment analysis was used to analyze the biological functions.

RESULTS

Males with higher GNRH1 and GNRHR have better overall survival (P < 0.05, HR < 1), while females with higher expression have a trend toward worse overall survival (P < 0.05, HR > 1). Gene set enrichment analysis identified GNRH1 and GNRHR exert opposite regulatory roles in myogenesis (M5909), interferon-α response (M5911), interferon-γ response (M5913), inflammatory response (M5932) and TNF-α signaling via NF-κβ (M5890) between males and females. The five functions are up-regulated in females (NES > 0), while down-regulated in males (NES < 0). GNRH1 in females was positively correlated with CD3D (R-value > 0 and P < 0.05), while GNRHR in males was negatively correlated with CD247, CD3D and CD3E (R-value < 0 and P < 0.05).

CONCLUSION

GNRH1 and GNRHR have opposite effects on overall survival in different genders, and exert opposite roles in immune-related functions between different genders, which could emerge as a contributor to gender disparity of BlCa prognosis.

Antitumor efficacy of edotecarin as a single agent and in combination with chemotherapy agents in a xenograft model

The novel indolocarbazole edotecarin (J-107088, formerly ED-749) differs from other topoisomerase I inhibitors both pharmacokinetically and pharmacodynamically. In vitro, it is more potent than camptothecins and has a variable cytotoxic activity in 31 different human cancer cell lines. Edotecarin also possesses greater than additive inhibitory effects on cell proliferation when used in combination with other agents tested in vitro against various cancer cell lines. The present in vivo studies were done to extend the in vitro findings to characterize the antitumor effects of edotecarin when used either alone or in combination with other agents (i.e., 5-fluorouracil, irinotecan, cisplatin, oxaliplatin, and SU11248) in the HCT-116 human colon cancer xenograft model. Treatment effects were based on the delay in onset of an exponential growth of tumors in drug-treated versus vehicle control-treated groups. In all studies, edotecarin was active both as a single agent and in combination with other agents. Combination therapy resulted in greater than additive effects, the extent of which depended on the specific dosage regimen. Toxicity in these experiments was minimal. Of all 359 treated mice, the six that died of toxicity were in the high-dose edotecarin/oxaliplatin group. The results suggest that edotecarin may serve as effective chemotherapy of colon cancer when used as a single agent, in combination with standard regimens and other topoisomerase inhibitors or with novel agents, such as the multitargeted tyrosine kinase inhibitor SU11248.

Camptothecins

Camptothecin analogues and derivatives appear to exert their antitumour activity by binding to topoisomerase I and have shown significant activity against a broad range of tumours. In general, camptothecins are not substrates for either the multidrug-resistance P-glycoprotein or the multidrug-resistance-associated protein (MRP). Because of manageable toxicity and encouraging activity against solid tumours, camptothecins offer promise in the clinical management of human tumours. This review illustrates the proposed mechanism(s) of action of camptothecins and presents a concise overview of current camptothecin therapy, including irinotecan and topotecan, and novel analogues undergoing clinical trails, such as exatecan (DX-8951f), IDEC-132 (9-aminocamptothecin), rubitecan (9-nitrocamptothecin), lurtotecan (GI-147211C), and the recently developed homocamptothecins diflomotecan (BN-80915) and BN-80927.

The clinical development of 9-aminocamptothecin

9-Aminocamptothecin (9-AC) is a topoisomerase I-targeting agent first synthesized by Wani and Wall in 1986. Because of its potent in vitro effects and promising preclinical activity in colorectal cancer animal models, it was designated a high-priority compound for further drug development by the NCI. In 1993, 9-AC first entered clinical trials as a 72-hour intravenous (i.v.) infusion. Predictable myelosuppression was the major dose-limiting toxicity, and pharmacokinetic studies showed a relatively short plasma half-life and unstable lactone ring. Unfortunately, phase II studies using this schedule showed minimal or no activity in tumors such as colorectal and lung cancer. Modest activity was observed in ovarian cancer and in refractory lymphomas. Efforts to improve systemic drug exposure by utilizing alternative schedules of administration of 9-AC such as prolonged, continuous intravenous infusions have also been tested. However, phase II studies of 120-hour weekly infusions of 9-AC have not shown improved activity against solid tumors such as colorectal cancer. More recently, a daily times 5 days i.v. administration schedule has been tested. Currently, further development of intravenously administered 9-AC for the treatment of colorectal cancer is not promising. Thus, topotecan and irinotecan remain the only two successfully developed topoisomerase I-targeting drugs in the United States. This experience with 9-AC raises important questions regarding how to best select new topoisomerase I-targeting drugs for future clinical development.

Phase I pharmacologic study of oral topotecan and intravenous cisplatin: sequence-dependent hematologic side effects

PURPOSE

In in vitro studies, synergism and sequence-dependent effects were reported for the combination of topotecan and cisplatin. Recently, an oral formulation of topotecan became available. This phase I study was performed to assess the feasibility of the combination of oral topotecan and cisplatin, the pharmacokinetic interaction, and sequence-dependent effects.

PATIENTS AND METHODS

Topotecan was administered orally (PO) daily for 5 days in escalating doses and cisplatin was given intravenously (IV) at a fixed dose of 75 mg/m(2) either before topotecan administration on day 1 (sequence CT) or after topotecan administration on day 5 (sequence TC) once every 3 weeks. Patients were treated in a randomized cross-over design.

RESULTS

Forty-nine patients were entered onto the study; one patient was not eligible. Sequence CT induced significantly more severe myelosuppression than did sequence TC, and the maximum-tolerated dosage of topotecan in sequence CT was 1.25 mg/m(2)/d x 5. In sequence TC, the maximum-tolerated dosage of topotecan was 2.0 mg/m(2)/d x 5. Dose-limiting toxicity consisted of myelosuppression and diarrhea. Pharmacokinetics of topotecan and cisplatin were linear over the dose range studied; no sequence-dependent effects were observed. In addition, topotecan did not influence the protein binding of cisplatin or the platinum-DNA adduct formation in peripheral leukocytes in either sequence.

CONCLUSION

The recommended dosages for phase II studies involving patients like the patients in our study are topotecan 1.25 mg/m(2)/d PO x 5 preceded by cisplatin 75 mg/m(2) IV day 1 once every 3 weeks, and topotecan 2.0 mg/m(2)/d PO followed by cisplatin 75 mg/m(2) IV day 5. No pharmacokinetic interaction could be discerned in our study. The antitumor efficacy of both schedules should be evaluated in a randomized phase II study.

Design and synthesis of water-soluble glucuronide derivatives of camptothecin for cancer prodrug monotherapy and antibody-directed enzyme prodrug therapy (ADEPT)

Glucuronide prodrugs of 9-aminocamptothecin were synthesized. Prodrug 4, in which 9-aminocamptothecin was connected to glucuronic acid by an aromatic spacer via a carbamate linkage, was stable in both aqueous solution and human plasma. Prodrug 4 and its potassium salt 12 were 20-80-fold less toxic than 9-aminocamptothecin to human tumor cell lines. The simultaneous addition of beta-glucuronidase and 4 or 12 to tumor cells resulted in a cytotoxic effect equal to that of 9-aminocamptothecin alone. Prodrugs 4 and 12 were over 80 and 4000 times more soluble than 9-aminocamptothecin in aqueous solutions at pH 4.0, respectively. Compounds 4 and 12 may be useful for prodrug monotherapy of tumors that accumulate extracellular lysosomal beta-glucuronidase as well as for antibody-directed enzyme prodrug therapy (ADEPT) of cancer.