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A phase I study of high-dose calcitriol in combination with temozolomide for patients with metastatic melanoma
Erin Pettijohn1, Brenda Martone2, Alfred Rademaker3
1Division of Hematology/Oncology, Northwestern University, 676 N. St Clair, Suite 850, Chicago, IL 60611, USA. erin-pettijohn@northwestern.edu.
Background:
Temozolomide is efficacious as an oral alternative for patients with metastatic melanoma (MM). Calcitriol has anti-proliferative properties and vitamin D receptor (VDR) polymorphisms are associated with alterations in melanoma susceptibility and progression.
Methods:
Tem 150 mg/m2 was administered on days 2-8 and 16-22 every 28 days. Calcitriol was given on days 1 and 15 every 28 days. VDR gene analysis was completed using PCR-RFLP based assays. Tolerability was the primary objective with secondary objectives of time to progression (TTP) and overall survival (OS).
Results:
Twenty pts with MM were registered. Cytopenias and thrombosis were the most common grade 3 or 4 toxicities. Median TTP was 1.8 mo. Pts with high-risk VDR genotype tt+/-ff (n = 6) had an OS of 3.8 mo from time of enrollment, compared to 7.4 mo for those with non-tt/ff genotypes (n = 11), although not statistically significant (HR = 1.20, 95% CI 0.41-3.53, p = 0.74).
Conclusions:
The extended dosing of Tem with calcitriol is a well-tolerated regimen. The trend toward improved OS in non-tt/ff VDR genotypes is consistent with prior studies associating the tt/ff genotype with biologic aggressiveness.
