Targeting angiogenesis in melanoma: prospects for the future

Angiogenesis has been identified as a relevant target for melanoma experimental therapeutics, based on preclinical and clinical studies. A variety of angiogenesis inhibitors are currently being tested in both metastatic and adjuvant melanoma clinical trials. To date, the most promising evidence of benefit is based on a statistically nonsignificant trend in survival gain reported in a randomized phase II trial combining bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor, with cytotoxic chemotherapy. Larger phase III studies are required to determine the true extent of clinical benefit with this class of agents. Key to these clinical trials is the need to include translational endpoints, since correlation of biological and clinical data will provide the opportunity to identify biomarkers predictive of treatment response. These biological studies will also aid our, as yet, poor understanding of the mechanism of action of angiogenesis inhibitors, as well as drug-related side effects. Finally, if these trials show meaningful clinical benefit, then careful consideration will need to be given when designing second-generation trials, in the light of novel gene-directed therapies currently showing promise in melanoma.

Phase I/II and pharmacodynamic study of dovitinib (TKI258), an inhibitor of fibroblast growth factor receptors and VEGF receptors, in patients with advanced melanoma

PURPOSE

Dovitinib (TKI258) is an orally available inhibitor of fibroblast growth factor (FGF), VEGF, and platelet-derived growth factor receptors. This phase I/II dose-escalation study was conducted to evaluate the safety, pharmacodynamics, and preliminary efficacy of dovitinib in the treatment of advanced melanoma.

EXPERIMENTAL DESIGN

Patients with advanced melanoma resistant or refractory to standard therapies or for whom no standard therapy was available were enrolled. Dovitinib was administered at doses ranging from 200 to 500 mg/d.

RESULTS

Forty-seven patients were enrolled. The most frequently reported adverse events were fatigue (77%; grade ≥3, 28%), diarrhea (77%; grade ≥3, 11%), and nausea (77%; grade ≥3, 9%). Six dose-limiting toxicities were observed in the 400-mg and 500-mg dose cohorts, which consisted of grade 3 nausea, fatigue, and diarrhea and grade 4 fatigue events. The maximum tolerated dose was 400 mg/d. The best tumor response was stable disease, which was observed in 12 patients. Increases in plasma FGF23, VEGF, and placental growth factor and decreases in soluble VEGF receptor 2 were noted during the first cycle of treatment, consistent with FGF receptor (FGFR) and VEGF receptor (VEGFR) inhibition. Dynamic contrast-enhanced MRI analysis showed a dose-dependent decrease in tumor blood flow and vascular permeability with dovitinib therapy. A decrease in FGFR phosphorylation was observed in paired tumor biopsy samples from a patient treated with dovitinib at a dose of 400 mg/d.

CONCLUSIONS

At a dose of 400 mg/d, dovitinib showed an acceptable safety profile and limited clinical benefit and inhibited FGFR and VEGFR.