Adding atezolizumab to platinum-based chemotherapy does not improve progression-free survival (PFS) in patients with relapsed ovarian cancer, according to a phase 3 study presented at ESMO Congress 2022. 

The study showed no improvement in PFS overall or among patients with PD-L1-positive tumors. However, the investigators considered preliminary overall survival (OS) results to be encouraging. 

The phase 3 ATALANTE/ENGOT-ov29 study (ClinicalTrials.gov Identifier: NCT02891824) enrolled 614 patients with relapsed nonmucinous epithelial ovarian cancer who had received 1 to 2 prior lines of chemotherapy. 


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Patients were randomly assigned 2:1 to receive atezolizumab with platinum-based chemotherapy and bevacizumab (n=410) or placebo with platinum-based chemotherapy and bevacizumab (n=204). 

At baseline, the median ages were 63 (range, 55-70) years in the atezolizumab arm and 64 (range, 55-71) years in the placebo arm. Most patients (75% in the atezolizumab arm and 72% in the placebo arm) had received 1 prior line of therapy. 

The percentage of patients with PD-L1 positivity was 38% in each arm. About half of patients (48% in the atezolizumab arm and 50% in the placebo arm) were PD-L1 negative. The remaining patients had unknown PD-L1 status. 

Patients were treated for up to 24 months in either arm. The study had coprimary endpoints of PFS in the intent-to-treat (ITT) population and in the population positive for PD-L1 (tumor proportion score ≥1%). 

The median follow-up was 36.6 months. In the ITT population, the median PFS was 13.5 months in the atezolizumab arm and 11.3 months in the placebo arm (hazard ratio [HR], 0.83; 95% CI, 0.69-0.99; P =.041). 

Among PD-L1-positive patients, the median PFS was 15.2 months in the atezolizumab arm and 13.1 months in the placebo arm (HR, 0.86; 95% CI, 0.63-1.16; P =.30). 

Despite this lack of improvement in PFS, the OS results in the atezolizumab arm are encouraging and warrant further follow-up, according to Jean-Emmanuel Kurtz, MD, PhD, of the Institut de Cancérologie Strasbourg Europe in France, who presented these findings at the meeting. 

In the ITT population, the median OS was 35.5 months in the atezolizumab arm and 30.6 months in the placebo arm (HR, 0.81; 95% CI, 0.65-1.01). 

Grade 3-4 treatment-related adverse events (TRAEs) were reported in 77% of patients in the atezolizumab arm and 70% of patients in the placebo arm. TRAEs of special interest were reported in 35% and 25%, respectively. 

There were 3 fatal TRAEs in the atezolizumab arm and 2 in the placebo arm. The causes of death in the atezolizumab arm were cardiac arrest, peritonitis, and acute myeloid leukemia. The causes of death in the placebo arm were pulmonary embolism and bowel perforation.

Disclosures: This research was supported by Hoffman La-Roche Ltd. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Kurtz JE, Pujade-Lauraine E, Oaknin A, et al. Phase III ATALANTE/ov29 trial: Atezolizumab (Atz) versus placebo with platinum-based chemotherapy (Cx) plus bevacizumab (bev) in patients (pts) with platinum-sensitive relapse (PSR) of epithelial ovarian cancer (OC). Presented at ESMO 2022; September 9-13, 2022. Abstract LBA30.