Interim data from a Phase IB trial evaluating the investigational anti-PD-1 immunotherapy, MK-3475, in patients with previously treated non-small cell lung cancer (NSCLC) were presented recently at the 15th World Conference on Lung Cancer in Sydney, Australia. Edward Garon, MD, Director of Thoracic Oncology, Jonsson Comprehensive Cancer Center at UCLA presented the findings.
MK-3475 is an investigational, highly selective anti–PD-1 immunotherapy designed to restore the natural ability of the immune system to recognize and target cancer cells by selectively achieving dual ligand blockade (PD-L1 and PD-L2) of the PD-1 protein. By blocking PD-1, MK-3475 enables activation of the immune system’s T cells that target cancer.
In the phase IB trial, a cohort of 38 patients with previously treated NSCLC were given MK-3475 10 mg/kg every 3 weeks. The objective response rate in patients with squamous and nonsquamous subtypes receiving MK-3475 was 24% by investigator-assessed, immune-related assessed criteria (irRC) and 21% per RECIST 1.1 criteria. The median overall survival at the time of analysis was 51 weeks with seven of the nine responders continuing on treatment. The median response duration had not been reached at the time of analysis.
The most commonly reported drug-related adverse events (all grades) in the study were rash (21%), pruritus (18%), fatigue (16%), diarrhea (13%), and arthralgia (11%). The majority of adverse events were low grade (grade 1–2), and there was one incident of grade 3 pulmonary edema.
Effect of PD-L1 Expression Status
An analysis of the relationship between PD-L1 expression status and response rates in this NSCLC patient cohort was also presented. Tumor samples were analyzed and classified as expressing either zero/low or high levels of PD-L1. High levels of expression according to the assay criteria were associated with response rates of 67% (95% confidence interval [CI] = 30–93) per irRC and 57% (95% CI = 18–90) per RECIST 1.1 criteria.
In comparison, tumor samples expressing zero/low levels of PD-L1, according to assay criteria, were associated with response rates of 4% (95% CI = 0–21) per irRC and 9% per RECIST (95% CI = 1–29). More data are needed to better understand the relationship between PD-L1 expression and response to MK-3475.
Based on these preliminary data, a phase II/III trial comparing two doses of MK-3475 vs docetaxel in patients with previously treated NSCLC who have received at least one prior treatment regimen has been initiated. ■