Chemotherapy for androgen- independent prostate cancer: myth or reality

Pre-clinical evaluation of 1-nitroacridine derived chemotherapeutic agent that has preferential cytotoxic activity towards prostate cancer

Chemotherapy in prostate cancer (CaP) even as an adjunct has not been a success. In this communication, we report the pre-clinical efficacy of a nitroacridine derivative, C-1748 (9[2'-hydroxyethylamino]-4-methyl-1-nitroacridine) in CaP cell culture and human xenograft animal models. C-1748, a DNA intercalating agent has been derived from its precursor C-857 that was a potent anti-cancer drug, but failed clinical development due to "high" systemic toxicities. Chemical modifications such as the introduction of a "methyl" group imparted novel properties, the most interesting of which is the difference in the IC(50) values between LnCaP (22.5 nM), a CaP cell line and HL-60, a leukemia cell line (>100 nM). Using gammaH2AX as an intervention marker of DNA double strand breaks, we concluded that C-1748 is more efficacious in CaP cells than in HL-60 cells. In hormone dependent cells, the androgen receptor (AR) was identified as an additional target of C-1748. In xenograft studies, administration of C-1748 intra-peritoneally inhibited tumor growth by 80-90% with minimal toxicity. These studies identify C-1748 as a novel acridine drug that has a high therapeutic index and low cytotoxicity on myelocytic cells with potential for clinical development.

Randomized, multicenter, phase II trial of two multicomponent regimens in androgen-independent prostate cancer

PURPOSE

Several multicomponent regimens have been reported to be useful in advanced androgen-independent prostate cancer. We used a randomized phase II design to evaluate and compare two such regimens. Patients were accrued primarily in the community setting.

PATIENTS AND METHODS

Patients with progressive, androgen-independent prostate cancer were randomly assigned to one of two treatments: either ketoconazole/doxorubicin alternating with vinblastine/estramustine (KA/VE) or paclitaxel, estramustine, and oral etoposide (TEE). Patients were prospectively stratified on the basis of disease volume. The primary end points were response and overall survival time.

RESULTS

A total of 75 patients were registered; 71 are included in the analysis. By the criterion of an 80% prostate-specific antigen reduction maintained for at least 8 weeks, 11 (30%) of 37 patients in the TEE arm responded, whereas 11 (32%) of 34 assigned to KA/VE responded. Median survival was 16.9 months (95% confidence interval [CI], 10.5 to 21.2 months) in the TEE arm and 23.4 months (95% CI, 12.9 to 30.6 months) for patients treated with KA/VE. Many patients (24%) failed to complete at least 6 weeks of therapy, including five (8%) treatment-related early deaths.

CONCLUSION

Each of these regimens produced clinically significant responses, and the observed median survival (18.9 months for all 71 patients) compares favorably with previously published results, especially in the community setting. Nonetheless, it is apparent that these first-generation regimens must be applied judiciously, and thus we view efforts at better patient selection and the development of more tolerable therapies as higher priorities than carrying either of these regimens to phase III evaluation in the cooperative group setting.