Phase II evaluation of temozolomide in metastatic choroidal melanoma

Temozolomide (Temodar) has demonstrated clinical activity against melanoma equivalent to that of intravenous dacarbazine (DTIC). Phase I clinical studies have shown that low dose chronic administration of temozolomide permits the delivery of higher dose intensities than a 5 day dose schedule. Temozolomide is hydrolysed to its active metabolite monomethyltriazenoimidazole carboxamide (MTIC) upon absorption from the gastrointestinal tract, while DTIC is inactive until it is metabolized in the liver to MTIC. In view of this, a higher concentration of MTIC will pass through the liver during the first pass when its source is temozolomide rather than DTIC. To determine if these characteristics of temozolomide will translate into a higher response rate than that achieved with DTIC, we conducted a phase II clinical trial of temozolomide in patients with uveal melanoma metastatic to the liver. Temozolomide was administered orally at a starting dose of 75 mg/m2 per day for 21 days every 4 weeks. Fourteen patients were enrolled in the trial. No complete or partial responses were observed. Stabilization of disease was achieved in two patients. The treatments were well tolerated. We conclude that, like DTIC, temozolomide at the dose and schedule studied in this trial is not effective for the control of metastatic melanoma of uveal origin.