Severe gastrointestinal toxicity of MEK inhibitors.

Gastrointestinal toxicities of MEK inhibitors in melanoma patients are frequent. In clinical trials, the most common digestive adverse events were nausea, vomiting, and diarrhoea. However, severe toxicities such as colitis and gastrointestinal perforation, some with fatal outcomes, have been reported. These rare but severe adverse events are not well described. We performed a retrospective analysis of all patients with stage IV and unresectable stage III melanoma treated with a MEK inhibitors at Saint-Louis Hospital, Paris, between 1 August 2013 and 15 October 2018. Among 119 patients exposed to MEK inhibitors, 78 were treated with trametinib, 19 with cobimetinib, four with binimetinib, and 18 patients with two different MEK inhibitors at separate times. All grade digestive adverse events were observed in 39 (32.7%) patients. Grade 3 and 4 adverse events occurred in 6 (5%) patients: 2 (1.7%) developed perforations, 3 (2.5%) had colitis and 1 (0.8%) had grade 4 diarrhoea. These adverse events were all reversible following a permanent discontinuation of the MEK inhibitors, or a temporary interruption followed by resumption at a dose lower than conventional posology. There were no fatal outcomes; however one patient had a permanent ileostomy. The mechanism underlying these toxicities is not well known. Clinicians should be aware of such toxicities.

Impact of radiotherapy administered simultaneously with systemic treatment in patients with melanoma brain metastases within MelBase, a French multicentric prospective cohort.

BACKGROUND: Melanoma brain metastases (MBMs) are historically associated with poor prognosis. Radiation therapy is conventionally associated with a high local control rate. Development of targeted therapy and immunotherapy has improved overall survival (OS) and intracranial response rate, but about 50% of patients failed to respond to these novel therapies. The objective of this study was to assess the impact of combined radiotherapy (cRT) on overall survival in a large multicenter real-life prospective cohort of patients with MBM treated with immunotherapy or targeted therapy. PATIENTS AND METHODS: Clinical data from 262 patients with MBM were collected via MelBase, a French multicentric biobank prospectively enrolling unresectable stage III or IV melanoma. Two groups were defined: patients receiving cRT (cRT group) or not receiving cRT (no-cRT group). Primary end-point was OS. Propensity score weighting was used to correct for indication bias. RESULTS: Among the 262 patients, 93 (35%) received cRT (cRT group). The patients were treated with immunotherapy in 69% and 60% and with targeted therapy in 31% and 40% of the cRT and no-cRT groups, respectively. With a median follow-up of 6.9 months, median OS was 16.8 months and 6.9 months in the cRT and no-cRT groups, respectively. After propensity score weighting, cRT was associated with longer OS (hazard ratio = 0.6, 95% confidence interval: 0.4-0.8; p=0.007). Median OS after ponderation was 15.3 months and 6.2 months in the cRT and no-cRT groups, respectively. CONCLUSION: This study shows that cRT may be associated with a significant decrease of 40% in the risk of death in patients with MBM treated with systemic therapy.