Vemurafenib en dabrafenib in combinatie met radiotherapie en het risico op verergerde radiotoxiciteit

OBJECTIVE Firstly, to evaluate radiotoxicity in a cohort with patients receiving both radiotherapy and a BRAF inhibitor (BRAFil. Secondly, to identify whether the BRAFi used, dabrafenib or vemurafenib, is related to radiotoxicity. DESIGN This study is a retrospective cohort study, reflecting daily clinical practice. METHODS In total, 119 patients were included in this analysis. Patients were treated with vemurafenib In = 42) or dabrafenib In = 77) in combination with radiotherapy within a time frame of two months. The incidence of induced radiotoxicity was compared between both groups with a Fisher's exact test. A logistic regression analysis was performed to identify potential factors related to the probability of experiencing induced radiotoxicity: type of BRAFi. combination therapy with a MEK inhibitor, age, sequence of treatment and location, cumulative radiation dose and total incidences of radiotherapy. RESULTS Induced radiotoxicity was seen in 6.7% of all patients. In the vemurafenib group 4.8% of patients experienced induced radiotoxicity compared to 7.8% in the dabrafenib group, this difference was not significant (P = 0.71). The logistic regression analysis revealed that none of the analyzed factors were related to the probability of experiencing induced radiotoxicity. CONCLUSION Both vemurafenib and dabrafenib administered in combination with radiotherapy induced radiotoxicity. No preference for dabrafenib over vemurafenib exists. The induced toxicity was manageable and did not lead to fatalities in this cohort. No predictive factors could be identified.