Association of pyrexia and durable response in advanced melanoma patients treated with the combination of dabrafenib and trametinib.

Abstract

e19046 Background: Pyrexia (fever) is a common adverse event associated with combined BRAF and MEK inhibition (dabrafenib and trametinib). Although the mechanism of fever is unclear, we explore pyrexia as a pharmacodynamic marker for clinical response. Methods: A phase II international trial with dabrafenib and trametinib in metastatic melanoma (MM) and colorectal cancers (CRC) harboring BRAF mutations is ongoing. Twenty-nine patients (pts) were enrolled at UCSF between January 2011 and January 2012. Fevers were graded based on temperature and coinciding symptoms, and an episode of pyrexia was defined as a temperature of >100 °F at least once a day for one or more consecutive days. Tumor assessments were performed every 8 weeks (wks). Results: To date, 13 pts with MM and 5 with CRC had tumor assessments up to 24 wks. In MM, pyrexia was reported 2 or more times in 7 pts; 5 had none, and 1 reported one episode of Grade 1 pyrexia. Episodes occurred 2-4 wks after starting treatment, and time between subsequent recurrences ranged from 1 to 25 wks. Neutrophil counts showed early fluctuations, but none had neutropenia. Of the 7 pts with recurring fevers, 5 had partial responses and 2 had stable disease at 8 wks. Of the 6 pts with nonrecurring or no fevers, 2 had partial responses at 8 wks, and 1 progressed. At 24 wks, all 7 pts with ≥ 2 fever episodes remained progression-free, whereas 0/6 pts with < 2 fever episodes were progression-free (p < 0.001). Pts without progression continued to have recurring fevers (median = 4). There were no differences by disease stage (12 of 13 with M1c) or mutation status (10 with V600E; 2 with V600K; 1 with V600E + V601I). While pts with CRC had pyrexia, no association between pyrexia and response was noted; however, only 5 pts are included in this analysis. Conclusions: In this limited analysis of pts with MM, recurrent fevers were associated with durable response (≥ 24 wks). These results suggest that pyrexia could be a marker for inflammation and antitumor activity. Further studies are underway to characterize cytokine profiles and immune responses. [Table: see text]