Chemotherapy in patients with metaststic melanoma after progression on BRAF/MEK inhibitors

Background

Metastatic melanoma remains a disease with poor prognosis even in patients with BRAF mutation, treated by BRAF/MEK inhibitors. In many countries immune checkpoints inhibitors which could be used for 2nd line treatment are not registered, or not reimbursed. At the same time, experimantal evidence supports enhancing the effectiveness of chemotherapy after blocking the MAP-kinase pathway. We evaluated the immediate effectiveness of chemotherapy in patients after progression or intolerance on BRAF/MEK inhibitors

Methods

We conducted a retrospective analysis of all patients (pts) who received paclitaxel 175 mg / m2 day1 + carboplatin AUC = 5 day 1 (PC) from January 1 2012 to Mar 30 2016 (n = 55). Group 1 (n = 26) was treated with BRAF / MEK inhibitors (vemurafenib, dabrafenib, trametinib, encorafenib or binimetinib) before PC, group 2 (n = 29) received no inhibitors of BRAF / MEK prior to PC

Results

Both groups did not differ in demographic characteristics (mean age 52.5 ± 12,4 years in group 1 and 53.7 ± 11,6 years respectively, p = 0.5, males 46.1% and 58.6% respectively, p = 0.78), the primary tumor origin (Unknown 15% and 17.2% respectively, skin 85% and 81.8% respectively p> 0.5), or the tumor stage at the start of chemo (III unresectable 7.6% and 0%, IV M1a 11.5% and 13.6%, IV M1b 15.4% and 18.2%, IV M1c 65.3% and 68.2%, respectively, p > 0.5). BRAF mutations rate was higher in Group 1 (96,2% vs 24,1%, p  0.05). Best overall response rate was calculated (Table 1). The median time to progression in Group 1 was 16 weeks (95% CI 6.12 to 23.87 months) and 7.0 weeks (95% CI 5.17 to 8,28) in Group 2; p = 0.019, HR = 2,14 (95% CI 1.08 to 4.21). The median overall survival can not be calculated correctly due to short follow-up (median 28 weeks).

Best overall response rate