Robert H. I. Andtbacka, MD, CM, a surgeon and investigator with Intermountain Healthcare and Huntsman Cancer Institute, discusses overall survival (OS) findings from the phase III OPTiM study that explored the intralesional injection talimogene laherparepvec (T-VEC) in patients with unresectable melanoma.
The phase III OPTiM study compared T-VEC with GM-CSF in 436 patients with unresected stage IIIB/C and IV melanoma. At the primary survival analysis, the median OS was 23.3 months with T-VEC compared with 18.9 months for GM-CSF (HR = 0.787; 95% CI, 0.62-1.00; P
= .051). The durable response rate with T-VEC was 16% versus 2% for GM-CSF.
The 4.4-month difference in survival is clinically significant, but narrowly missed statistical significance, Andtbacka suggests. The lack of significance could be the result of the study not being adequately powered to look at a small difference in OS, since survival was a secondary endpoint. Clinically, Andtbacka believes the median survival and the durability of response is more important for determining treatment.
The therapies received following progression on the trial were similar between the two arms, Andtbacka notes. In a subanalysis, it was found that more patients in the T-VEC group had advanced stage IV M1b/M1c disease compared with the GM-CSF, suggesting a worse outcome. Additionally, a higher number of patients with ECOG performance status 1 compared with 0 were enrolled into the T-VEC group versus GM-CSF, Andtbacka notes.
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