Chemotherapy of malignant melanoma

Metabolic activation of 4-hydroxyanisole by isolated rat hepatocytes

A tyrosinase-directed therapeutic approach for treating malignant melanoma uses depigmenting phenolic prodrugs such as 4-hydroxyanisole (4-HA) for oxidation by melanoma tyrosinase to form cytotoxic o-quinones. However, in a recent clinical trial, both renal and hepatic toxicity were reported as side effects of 4-HA therapy. In the following, 4-HA (200 mg/kg i.p.) administered to mice caused a 7-fold increase in plasma transaminase toxicity, an indication of liver toxicity. Furthermore, 4-HA induced-cytotoxicity toward isolated hepatocytes was preceded by glutathione (GSH) depletion, which was prevented by cytochrome p450 inhibitors that also partly prevented cytotoxicity. The 4-HA metabolite formed by NADPH/microsomes and GSH was identified as a hydroquinone mono-glutathione conjugate. GSH-depleted hepatocytes were much more prone to cytotoxicity induced by 4-HA or its reactive metabolite hydroquinone (HQ). Dicumarol (an NAD(P)H/quinone oxidoreductase inhibitor) also potentiated 4-HA- or HQ-induced toxicity whereas sorbitol, an NADH-generating nutrient, prevented the cytotoxicity. Ethylenediamine (an o-quinone trap) did not prevent 4-HA-induced cytotoxicity, which suggests that the cytotoxicity was not caused by o-quinone as a result of 4-HA ring hydroxylation. Deferoxamine and the antioxidant pyrogallol/4-hydroxy-2,2,6,6-tetramethylpiperidene-1-oxyl (TEMPOL) did not prevent 4-HA-induced cytotoxicity, therefore excluding oxidative stress as a cytotoxic mechanism for 4-HA. A negligible amount of formaldehyde was formed when 4-HA was incubated with rat microsomal/NADPH. These results suggest that the 4-HA cytotoxic mechanism involves alkylation of cellular proteins by 4-HA epoxide or p-quinone rather than involving oxidative stress.

Chemotherapy for eye cancer

Chemotherapy has been used to treat a multitude of eye cancers. We attempted to review the role of chemotherapy in the treatment of ocular, adnexal, and orbital malignancies by conducting an extensive search of the medical literature. Unfortunately, the published reports typically contain few patients with limited follow-up, precluding definitive recommendations. For most eye cancers, multicenter trials will offer the potential to gather the numbers of patients required to determine the clinical utility of chemotherapy.

Management of stage I malignant melanoma

BACKGROUND

Because of the rising incidence of melanoma, dermatologists are increasingly responsible for diagnosing and managing patients with this cutaneous malignancy. Fortunately, with the increased awareness and emphasis on early detection, most patients will present with tumors that have not yet spread beyond their primary focus in the skin (ie, Stage I). Dermatologists must, therefore, be fully versed in the diagnosis and management of Stage I melanoma.

OBJECTIVE

This review article focuses on the most important issues related to the diagnosis and management of Stage I melanoma. An emphasis will be placed on surgical management.

RESULTS

The mainstay of therapy for most patients with Stage I melanoma is surgery. The important principles of diagnostic biopsy and surgical excision will be discussed. There are several additional modalities that may be useful as adjuvants to surgical therapy or as primary therapy in situations when surgery is not feasible. Those include elective lymph node dissection, hyperthermic isolation limb perfusion, radiotherapy, cryotherapy, chemotherapy, and immunotherapy. These will all be reviewed.

CONCLUSIONS

With a thorough understanding of the important principles and controversies related to the management of Stage I melanoma, dermatologists can effectively manage the growing number of patients with this malignancy.

Chemohormone therapy of metastatic melanoma with megestrol acetate plus dacarbazine, carmustine, and cisplatin

BACKGROUND

Chemotherapy with dacarbazine, carmustine, and cisplatin produces a modest objective response rate in melanoma. Megestrol acetate may ameliorate cachexia, abrogate drug resistance, and increase survival time in melanoma.

METHODS

Nineteen patients with metastatic melanoma (16 evaluable) treated with dacarbazine (220 mg/m2/day for 3 days, intravenously [IV]), cisplatin (25 mg/m2/day for 3 days IV) every 3 weeks, and carmustine (150 mg/m2 IV single dose every 6 weeks) together with megestrol acetate (160 mg/day by mouth continuously) starting 2 days before chemotherapy.

RESULTS

This regimen was well tolerated and resulted in a mean net weight gain of 1.45 kg. A 47% objective response rate was observed in all patients, including visceral sites of response, with a 39+ week median duration of response and median survival time of 16.7+ months in all evaluable patients.

CONCLUSIONS

In this small Phase II study, the authors showed that megestrol acetate may contribute to a high objective response rate and prolonged median survival when used with a chemotherapy regimen of dacarbazine, carmustine, and cisplatin.