in patients with unresectable stage 3 non–small-cell lung cancer.
Combinations of the PD-L1 inhibitor durvalumab (Imfinzi, AstraZeneca) with the anti-CD73 monoclonal antibody oleclumab or the anti-NKG2A monoclonal antibody monalizumab led to improved overall response rate and progression-free survival compared to durvalumab alone.
The findings support further study in a phase 3 clinical trial, according to the authors of the study recently published in the Journal of Clinical Oncology.
Durvalumab is the standard treatment following consolidation therapy of chemoradiotherapy in unresectable stage 3 non–small-cell lung cancer (NSCLC). Although it extended progression-free survival (PFS) and overall survival in the PACIFIC phase 3 study, some patients experience a recurrence, which has led to exploration of immunotherapy combinations.
Oleclumab inhibits the enzyme CD73, found on the surfaces of both tumor and immune cells. Its activity leads to an immunosuppressive effect in the tumor microenvironment, and preclinical studies have shown that it can have an additive antitumor effect when combined with PD-1 or PD-L1 inhibitors. A phase 1 study also suggested efficacy. Monalizumab blocks interactions between major histocompatibility complex-E (HLA-E) and an inhibitor receptor. A number of tumors overexpress HLA-E, triggering inhibitor signals that inhibit natural killer and CD8+ T cells.
“COAST was an interesting study that, although not definitive, suggested that the combination of durvalumab with oleclumab or with monalizumab was more effective than durvalumab alone in the consolidation setting after definitive concurrent chemoradiation for patients with stage 3 unresectable NSCLC,” said Nathan Pennell, MD, PhD, who wrote an accompanying editorial.
Despite the positive signal, Dr. Pennell expressed some skepticism that the combinations would pass a phase 3 test. He questioned the choice of response rate as the primary endpoint of the phase 2 study, and noted that the durvalumab arm had worse progression-free survival (PFS) than the previous PACIFIC trial. It could be that the clinical characteristics of the study population differed between the two trials, in which case the improved objective response rate (ORR) and PFS results should be encouraging. It’s also possible the COAST trial’s small sample size led to a mismatch between the control and treatment group despite randomization, in which case the findings may not be valid.
“These are the kinds of issues that keep drug developers up at night. There really is no way to know which scenario is correct without doing the larger trial. I do hope though that the phase 3 trials have robust biomarker analysis including PDL1 to make sure the arms are as well matched for known prognostic and predictive markers as possible,” said Dr. Pennell, who is vice chair of clinical research at Taussig Cancer Institute.
The study details
The researchers randomized 189 patients to durvalumab, durvalumab plus oleclumab, or durvalumab plus monalizumab between January 2019 and July 2020. After a median follow-up of 11.5 months, there was a higher confirmed objective response rate in the durvalumab plus oleclumab group (30.0%; 95% confidence interval, 18.8%-43.2%) and the durvalumab plus monalizumab group (35.5%; 95% CI, 23.7%-48.7%) versus durvalumab alone (17.9%; 95% CI, 9.6%-29.2%).
Compared to durvalumab alone, there was improved PFS in both durvalumab plus oleclumab (stratified hazard ratio, 0.44; 95% CI, 0.26-0.75) and durvalumab plus monalizumab (HR, 0.42; 95% CI, 0.24-0.72). At 12 months, PFS was 62.6% (95% CI, 48.1-74.2%) for durvalumab plus oleclumab, 72.7% (95% CI, 58.8-82.6%) for durvalumab plus monalizumab, and 33.9% (95% CI, 21.2-47.1%) for durvalumab alone.
The study was funded by AstraZeneca.