Both combinations – durvalumab plus either the anti-CD73 monoclonal antibody oleclumab or the anti-NKG2A mAb monalizumab – also numerically improved objective response rate. “Safety profiles were consistent across arms and no new safety signals were identified,” said Alexandre Martinez-Marti, MD, the lead investigator on the phase 2 trial, dubbed COAST, which he presented (abstract LBA42) at the 2021 European Society for Medical Oncology Congress on Sept. 17.
“These data support further evaluations of these combinations,” said Dr. Martinez-Marti, also a thoracic medical oncologist at the Vall d’Hebron Institute of Oncology in Barcelona.
Durvalumab is already established as a standard of care option for patients with unresectable stage 3 NSCLC who don’t progress after concurrent chemoradiation. There’s been preliminary data suggesting the benefits might be greater with oleclumab or monalizumab, so the study team looked into the issue.
They randomized 66 patients with unresectable stage 3 NSCLC and no progression after chemoradiotherapy to durvalumab 1,500 mg IV every 4 weeks; 59 others to durvalumab at the same dosage plus oleclumab 3,000 mg IV every 2 weeks for the first two cycles then every 4 weeks, and 61 were randomized to durvalumab plus monalizumab 750 mg IV every 2 weeks.
Patients were treated for up to 12 months, and they started treatment no later than 42 days after completing chemoradiation.
Over a median follow-up of 11.5 months, median progression-free survival (PFS) was 6.3 months in the durvalumab arm, but 15.1 months with the monalizumab combination (PFS hazard ratio versus durvalumab alone, 0.65; 95% CI, 0.49-0.85), and not reached in the oleclumab arm (PFS HR, 0.44; 95% CI, 0.26-0.75).
There were only a few complete responders across the study groups. Partial responses rates were 22.4% of the durvalumab alone arm, 36.7% in the oleclumab group, and 32.3% in the monalizumab arm.
The investigator assessed objective response rate was 25.4% with durvalumab alone, 38.3% in the oleclumab group, and 37.1% with the monalizumab combination. Curves started to separate from durvalumab monotherapy at around 2-4 months.
“Overall, the safety profiles of the two combinations were generally similar to the safety profile of durvalumab alone,” Dr. Martinez-Marti said. The rate of grade 3 or higher treatment-emergent events incidence was 39.4% with durvalumab, 40.7% the oleclumab combination, and 27.9% with monalizumab.
The most common grade 3/4 events were pneumonia (5.9%) and decreased lymphocyte count (3.2%); both were less common with the monalizumab combination.
Combined rates of pneumonitis and radiation pneumonitis of any grade were 21.2% with durvalumab, 28.8% in the oleclumab group, and 21.3% with monalizumab.
The groups were generally well balanced at baseline. The majority of subjects were men, White, and former smokers. Most subjects had stage 3A or 3B disease.
The work was funded by AstraZeneca. The investigators disclosed numerous ties to the company, including Dr. Martinez-Marti, who reported personal fees, travel expenses, and other connections.
This article was updated 9/24/21.