NATIONAL HARBOR, MD – interim results of a phase 3 trial suggest.
When compared with platinum-based chemotherapy, atezolizumab significantly improved OS in patients who had PD-L1 expression of 50% or greater on tumor cells (TC) or 10% or greater on tumor-infiltrating immune cells (IC).
Patients with lower levels of PD-L1 expression had a numerical, but not statistically significant, benefit in OS with atezolizumab.
, of Georgetown University, Washington, presented these results, from the , as a late-breaking abstract at the annual meeting of the Society for Immunotherapy of Cancer.
The trial enrolled treatment-naive, PD-L1–selected patients with stage IV NSCLC. Patients with EGFR-positive or ALK-positive NSCLC were excluded.
The overall population consisted of 554 patients with PD-L1 expression of at least 1% on TC or IC (TC1/2/3 or IC1/2/3). There were 328 patients with PD-L1 expression of at least 5% on TC or IC (TC2/3 or IC2/3) and 205 patients with PD-L1 expression of at least 50% on TC or 10% on IC (TC3 or IC3).
All patients were randomized to receive atezolizumab or platinum-based chemotherapy. Atezolizumab was given at 1,200 mg every 3 weeks until disease progression or loss of clinical benefit. In the chemotherapy arm, patients with nonsquamous NSCLC received cisplatin or carboplatin plus pemetrexed, and patients with squamous NSCLC received cisplatin or carboplatin plus gemcitabine. Chemotherapy was given for 4-6 cycles, after which patients received pemetrexed (nonsquamous) or best supportive care (squamous) until progression.
Baseline characteristics were similar between the treatment arms and across the PD-L1 subgroups.
OS was evaluated hierarchically, starting with the TC3 or IC3 population. This group had a significant improvement in OS with atezolizumab. At a median follow-up of 15.7 months, the median OS was 13.1 months with chemotherapy and 20.2 months with atezolizumab (hazard ratio, 0.59; P = .0106).
The TC2/3 or IC2/3 population had a numerical, but not significant, improvement in OS with atezolizumab. At a median follow-up of 15.2 months, the median OS was 14.9 months with chemotherapy and 18.2 months with atezolizumab (HR, 0.72; P = .0416).
“The prespecified alpha boundary was not crossed in this analysis,” Dr. Giaccone said. “Therefore, it cannot be considered statistically significant, although, numerically, there is clearly an advantage with atezolizumab versus chemotherapy.”
There was no significant improvement in OS in the overall population (TC1/2/3 or IC1/2/3). At a median follow-up of 13.4 months, the median OS was 14.1 months in the chemotherapy arm and 17.5 months in the atezolizumab arm (HR, 0.83; P = .1481).
Dr. Giaccone noted that 29.6% of patients in the atezolizumab arm and 49.5% of those in the chemotherapy arm received at least one subsequent cancer therapy. The proportion of patients that received second-line cancer therapies was similar across the PD-L1 subgroups.
Progression-free survival (PFS) was significantly better with atezolizumab, regardless of PD-L1 expression.