The addition of atezolizumab (Tecentriq) to chemotherapy demonstrated noninferior survival compared with placebo plus chemotherapy in patients with advanced or recurrent endometrial cancer, according to a presentation on the phase 3 AtTEnd/ENGOT-EN7 trial (NCT03603184) at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting.
The trial included patients with PD-L1-positive tumors who had progressed after platinum-based chemotherapy. Patients were randomized 1:1 to receive atezolizumab plus chemotherapy or placebo plus chemotherapy.
The primary endpoint of progression-free survival (PFS) showed a hazard ratio (HR) of 0.82 (95% CI, 0.67-1.00), meeting the prespecified criteria for noninferiority (HR <1.0). While the study met its primary endpoint, the benefit in PFS was not statistically significant.
Overall survival (OS) data were also presented, showing an HR of 0.89 (95% CI, 0.73-1.08), favoring atezolizumab, but this did not reach statistical significance.
Notably, a higher proportion of patients in the atezolizumab arm did not receive subsequent immunotherapy following treatment discontinuation (12.1%) compared with the placebo arm (29.2%).This suggests a potential for atezolizumab to provide durable benefit, reducing the need for further lines of therapy.
“[These findings] support atezolizumab plus chemotherapy as a potential new treatment option for patients with advanced or recurrent endometrial cancer,” said the presenter. “Further research is needed to identify biomarkers that may predict response to atezolizumab and to optimize treatment strategies.”
MMR status, survival outcomes did not considerably differ between the 2 regimens.After a median follow-up of 49.6 months,the median OS was 30.0 months (95% CI, 23.8-37.4) with atezolizumab vs 30.2 months (95% CI, 22.4-40.7) with placebo, and the 12- and 24-month rates were 77.8% vs 75.8% and 55.9% vs 58.8%, respectively (HR, 1.02; 95% CI, 0.78-1.34; P* = .6644). In the respective arms, 13.8% vs 24.3% received subsequent immunotherapy.
Additionally, among all comers, the progression-free survival (PFS) outcomes numerically favored atezolizumab. In the investigational and placebo arms, the median PFS was 9.9 months (95% CI, 9.3-12.0) vs 8.9 months (95% CI, 8.1-9.6), with respective 12- and 24-month rates of 44.7% vs 28.9% and 28.7% vs 16.8% (HR, 0.70; 95% CI, 0.58-0.86; *P = .0055). Moreover, a non-proportional hazards restricted mean survival time difference of 2.52 months (95% CI, 0.82-4.22) at 30 months was observed.
Among patients with dMMR disease, atezolizumab exhibited enhanced PFS outcomes vs placebo. With the respective regimens, the median PFS was not evaluable (95% CI, 12.3-NE) vs 6.9 months (95% CI, 6.2-9.0); and the respective 12- and 24-month PFS rates were 62.7% vs 23.3% and 52.1% vs 16.3% (HR, 0.35; 95% CI, 0.22-0.55; P* = .0002).
For those with non-dMMR status, noninferior PFS was observed with atezolizumab. The median PFS was 9.5 months (95% CI, 9.0-10.4) with atezolizumab vs 9.2 months (95% CI, 8.5-9.9) with placebo. The PFS rates were 39.1% vs 30.2% at 12 months and 21.7% vs 16.0% at 24 months in each respective arm (HR, 0.86; 95% CI,0.69-1.08; *P = .1885).
Furthermore, the objective response rate (ORR) and duration of response (DOR) among patients with dMMR status numerically favored the atezolizumab arm. The ORR with atezolizumab was 82.4% (95% CI, 71.4% vs 89.7%) with a complete response (CR) rate of 26.5% and a partial response (PR) rate of 55.9%; with placebo, the ORR was 75.7% (95% CI, 56.3%-84.7%), with a CR rate of 18.9% and a PR rate of 56.8%. Regarding DOR,the median values were not evaluable (95% CI,15.0-NE) with atezolizumab vs 4.9 months (95% CI, 4.3-8.4) with placebo; the 12- and 24-month rates were 66.9% vs 2