An exploratory study investigating the metabolic activity and local cytokine profile in patients with melanoma treated with pazopanib and paclitaxel.

BACKGROUND: There is a medical need for new drugs in patients with BRAF wild-type metastatic melanoma. Pazopanib is a multitarget tyrosine kinase inhibitor with antitumour and antiangiogenic activity. OBJECTIVES: The primary aim was to investigate the metabolic response to pazopanib monotherapy and pazopanib plus paclitaxel in patients with BRAF wild-type melanoma. Secondary end points were the early cytokine and chemokine profiles and histological findings. METHODS: Pazopanib (400 mg twice daily) was administered orally from days 1 to 10 and from days 14 to 70. An intravenous infusion with paclitaxel (150 mg m-2 body surface) was administered on days 14, 35 and 56. Metabolic response evaluation was performed before treatment, after treatment with pazopanib (day 10) and after treatment with pazopanib and paclitaxel (day 70). Skin biopsy of metastatic tissue for chemokine and cytokine expression analysis and histology and immunohistochemistry (CD68, CD163) evaluation, and blood samples were taken at the same time points. RESULTS: Two patients failed screening and 17 were dosed. Of 67 adverse events, nine (13%) were grade 3 or 4. Five of 14 evaluable patients had a partial metabolic response at day 10 under pazopanib monotherapy. The response rate at day 70 under combined pazopanib-paclitaxel treatment was 0%. Immunohistochemistry revealed an increase of M2-like macrophages in nonresponders compared with responders. We observed a significant upregulation of five cytokines (CXCL1, CXCL2, CXCL13, CCL22 and SPP1) in responding vs. nonresponding lesions. Overall, the median progression-free survival was 70 days (range 5-331), which did not differ significantly between responders (148 days) and nonresponders (70 days, P = 0·17). CONCLUSIONS: In this patient population pazopanib efficacy was limited. Response is associated with low M2-like macrophage density and increased expression of several chemokines.

Developments in targeted therapy in melanoma.

Melanomas are disease entities driven in part by the mitogen activated protein kinase (MAPK) pathway. The TCGA network recently defined four genetic subtypes based on the most prevalent significantly mutated genes, including mutant BRAF, mutant RAS (N/H/K), mutant NF1, and Triple wild-type melanoma (harboring none of the aforementioned mutations, but instead includes KIT, GNA and GNAQ mutations). The successful development of kinase inhibitors marked a milestone in the treatment of metastatic melanoma. Combination treatment with a BRAF- and MEK-inhibitor is the current standard of care for inoperable stage IIIC/IV BRAF-mutated melanoma. Recent data demonstrate excellent long-term outcome, especially in patients with normal baseline LDH levels, and confirm that there is a subset of BRAF inhibitor-naive patients who experience durable responses without progression on combination treatment. In the future, adding a third compound based on individual genetic alterations might further improve the outcome of targeted therapy.