Thoracic oncologists have been waiting for some positive data from checkpoint inhibitors in advanced mesothelioma for some time and this may have finally come in the form of the investigator-sponsored Maps-2 phase II study, presented at Asco on Monday. The Maps-2 study, which examined Bristol-Myers Squibb's (BMY) Opdivo with/without Yervoy in second or third-line patients showed an impressive set of survival curves that may set a new bar for combinations in this patient group.
The median overall survival for the Opdivo/Yervoy combo was not reached but the Kaplan-Meier plot suggests it will, when mature, exceed 12 months, possibly by some margin, with a median progression-free survival for the combo of 5.6 months (see table below). Such figures are considered very impressive in this extremely poor prognosis disease.
Yervoy if you do
Furthermore, survival measures for the combo exceeded single agent Opdivo in all respects, suggesting an additive benefit for the CTLA4 antibody. This was also seen as an important finding, given the disappointing outcome of the Determine trial, which examined Astrazeneca's (AZN) CTLA4 antibody, tremelimumab, against placebo in advanced mesothelioma last year.
With 125 patients enrolled, Maps-2 was of a sufficient size to give confidence in the robustness of the data. By contrast, most studies with checkpoint inhibitors in mesothelioma have been small as well as single arm, so outcome measures could be skewed. Compounding the problem is a well recognized difficulty of determining response in a disease where the tumor is located in the lining of the lungs.
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