Atezolizumab Combo Elicits No Significant Benefit in Ovarian Cancer

A regimen consisting of atezolizumab (Tecentriq), platinum-containing chemotherapy, and maintenance niraparib (Zejula) did not confer significantly improved outcomes vs chemotherapy plus niraparib alone among patients with late-relapsing recurrent ovarian cancer, according to final results from the phase 3 ENGOT-Ov41/GEICO 69-O/ANITA trial (NCT03598270) presented in a poster session at the European Society for Medical Oncology (ESMO) Congress 2025.¹

Across the intent-to-treat (ITT) population, the median overall survival (OS) was 32.2 months (95% CI, 27.1-34.8) with the atezolizumab regimen vs 27.1 months (95% CI, 23.2-32.3) with chemotherapy plus niraparib alone (HR, 0.91; 95% CI, 0.71-1.18). Subgroup analysis findings for OS were typically comparable with those reported in the ITT population.

Among those with PD-L1–negative disease, the median OS was 24.4 months (95% CI, 20.1-32.8) in the atezolizumab arm and 24.5 months (95% CI, 21.8-29.9) in the placebo arm (HR, 1.09; 95% CI, 0.78-1.51). In the PD-L1–positive population, the median OS was 41.7 months (95% CI, 32.3-47.3) vs 35.2 months (95% CI, 24.8-43.0) in each respective arm (HR, 0.81; 95% CI, 0.53-1.25).

Among patients without BRCA-mutated disease, the median OS was 29.4 months (95% CI, 24.4-34.5) with the atezolizumab regimen vs 24.2 months (95% CI, 20.6-29.5) with chemotherapy plus niraparib only (HR, 0.85; 95% CI, 0.66-1.10). In each respective arm, the median OS was 37.7 months (95% CI, 29.5-not evaluable [NE]) vs NE (95% CI, 31.0-NE) among patients with BRCA-mutated disease (HR, 1.73; 95% CI, 0.77-3.87).

Data revealed a more favorable OS prognosis in patients with PD-L1–positive status (HR, 0.60; 95% CI, 0.46-0.78) and BRCA mutations (HR, 0.45; 95% CI, 0.30-0.69) regardless of the treatment arm.

“Mature efficacy results from the ENGOT-Ov41/GEICO 69-O/ANITA trial are consistent with the primary analysis,² showing no clinically or statistically significant benefit from the addition of atezolizumab to [chemotherapy] and maintenance niraparib for late-relapsing [recurrent ovarian cancer],” lead study author Professor Antonio González-Martín, from GEICO and the Department of Medical Oncology and Program in Solid Tumors of Cima-Universidad de Navarra, Cancer Center Clínica Universidad de Navarra (CCUN) in Madrid, Spain, wrote with coauthors in the poster.¹ “No new safety concerns emerged with long-term follow-up. These findings should be considered when designing future trials in late-relapsing [recurrent ovarian cancer].”

In the double-blinded phase 3 ANITA trial, 417 patients were assigned to receive atezolizumab (n = 208) or placebo (n = 209) in combination with a carboplatin doublet during the chemotherapy phase. In the maintenance phase, patients received atezolizumab at 1200 mg or matched placebo on day 1 plus niraparib at an individualized starting dose of 300 mg or 200 mg on days 1 to 21 of each cycle.

The trial’s primary end point was investigator-assessed progression-free survival (PFS) across the ITT population. Secondary end points included duration of response (DOR), investigator-assessed PFS from the initiation of maintenance treatment, time to first subsequent therapy or death, time to second subsequent therapy or death, time to second progression or death, and OS.

Patients with measurable, high-grade serous, endometrioid, or undifferentiated late-relapsing ovarian cancer were eligible for enrollment on the trial. Other eligibility criteria included having no more than 2 prior lines of chemotherapy, no prior PARP inhibitors, no prior immune checkpoint inhibitors in any treatment setting, and an ECOG performance status of 0 or 1.

The median age was 63 years (range, 37-85) in the atezolizumab arm and 62 years (range, 23-82) in the placebo arm; most from each arm had an ECOG performance status of 0 (64% vs 61%) and high-grade serous histology (90% vs 94%). Additionally, most patients in each respective arm had 1 prior line of treatment (87% vs 87%), no BRCA mutations (88% vs 85%), PD-L1 negativity (56% vs 53%), and a chemotherapy backbone of pegylated liposomal doxorubicin (75% vs 77%).

In the ITT population, the atezolizumab combination produced numerical improvements in DOR (HR, 0.77; 95% CI, 0.57-1.06), PFS (HR, 0.86; 95% CI, 0.69-1.07), maintenance PFS (HR, 0.78; 95% CI, 0.60-1.01), and PFS2 (HR, 0.93; 95% CI, 0.74-1.18), but not time to first subsequent therapy (HR, 1.00; 95% CI, 0.82-1.23) or time to second subsequent therapy or death (HR, 1.01; 95% CI, 0.81-1.26). Among patients with PD-L1–positive status, the experimental regimen conferred numerical improvements across all secondary end points vs the placebo combination.

Any-grade adverse effects (AEs) occurred in 100% of the atezolizumab arm and 99% of the placebo arm, with 72% vs 68% experiencing grade 3 or higher treatment-related AEs. In each respective arm, 38% vs 30% had serious AEs, 24% vs 9% had immune-mediated AEs, and 55% vs 47% experienced AEs associated with niraparib dose reductions. Data showed that 25% from each arm had AEs leading to discontinuation of maintenance niraparib; 15% and 13% discontinued maintenance atezolizumab and placebo, respectively, due to AEs.

References

1. González-Martín A, Pérez MJR, Heitz F, et al. Final results from the ENGOT-Ov41/GEICO 69-O/ANITA randomised phase 3 trial of atezolizumab, platinum-based chemotherapy and maintenance niraparib for late-relapsing recurrent ovarian cancer. Presented at the European Society for Medical Oncology (ESMO) Congress 2025; October 17-21, 2025; Berlin, Germany. Abstract 1066P.
2. González-Martín A, Rubio MJ, Heitz F, et al. Atezolizumab combined with platinum and maintenance niraparib for recurrent ovarian cancer with a platinum-free interval >6 months: ENGOT-OV41/GEICO 69-O/ANITA phase III trial. J Clin Oncol. 2024;42(36):4294-4304. doi:10.1200/JCO.24.00668.