Retrospective study comparing survival when ipilimimab used with and without radiotherapy in patients with advanced melanoma.

Abstract

83 Background: Ipilimumab, a monoclonal antibody targeting CTLA-4, has increased median survival in patients with advanced melanoma from 6.4 to 10 months, with 20% of patients showing a sustained response. Preclinical and clinical studies have shown possible synergistic and abscopal effects between ipilimumab and radiotherapy. The aim of this study was to compare survival curves of patients who have received ipilimumab with and without radiotherapy, and also look at other potential prognostic indicators for patients with advanced melanoma. Methods: Data was collected retrospectively from patients with advanced melanoma treated with ipilimumab at Royal Cornwall Hospital (RCH), United Kingdom. The data collection proforma included: demographic details, BRAF status, treatments prior to and since ipilimumab, whether and when radiotherapy given, response, autoimmune phenomena documented, overall survival, and survival time since ipilimumab. Results: 43 patients (20 men and 23 women) have received ipilimumab for metastatic melanoma at RCH between 2011 and 2015. Age range 27-88 years, with a median age of 60 years. 13 were BRAF mutated, 28 were BRAF wild-type and 2 were unknown. 33% of patients who received ipilimumab had some response to it, with 21% achieving a complete response. 25% of patient who displayed autoimmune phenomena clinically responded to ipilimumab; only 15% of those who did not display autoimmune phenomena clinically responded. 20 patients received radiotherapy and 23 did not; there was no significant survival difference related to radiotherapy usage. Patients with the BRAF mutation had a shorter median survival than those who were BRAF wild-type. Conclusions: Although this study was retrospective and not randomised, it appears to show an increased likelihood of a response to ipilimumab in patients who also had autoimmune side effects from treatment. Patients with a BRAF mutation had a shorter median survival than those who were BRAF wild type. The addition of radiotherapy to ipilimumab did not appear to impact on survival or response, although, as the patients were not randomised as to whether they received radiotherapy it is difficult to draw firm conclusions from this.