BARCELONA – Nivolumab was associated with improved overall survival and a favorable safety profile, compared with chemotherapy, in patients with previously treated advanced esophageal squamous cell carcinoma (ESCC) in the open-label phase 3 ATTRACTION-3 study.
The overall survival (OS) benefit was observed regardless of tumor programmed death-ligand 1 (PD-L1) expression, Byoung Chul Cho, MD, reported at the European Society for Medical Oncology Congress.
The findings were reported online simultaneously in The Lancet Oncology.
Median OS at a minimum follow-up of 17.6 months was 10.9 vs. 8.4 months in 210 patients randomized to receive treatment with the PD-1 inhibitor nivolumab and 209 who received chemotherapy, respectively (hazard ratio, 0.77), said Dr. Cho of Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea.
“Notably, there was a 13% and 10% improvement in overall survival rates at 12 months (47% vs. 34%) and 18 months (31% vs. 21%), respectively,” he said, also noting that the HRs for death favored nivolumab vs. chemotherapy across multiple prespecified subgroups, including those based on tumor PD-L1 expression (HRs, 0.69 and 0.84 for PD-L1 of 1% or greater and less than 1%, respectively).
No meaningful difference was seen in progression-free survival between the nivolumab and chemotherapy groups (12% vs. 7%; HR, 1.08), or in objective response rates (19% vs. 22%), he said.
“However, responses were substantially more durable with nivolumab, compared to chemotherapy; duration of response was 6.9 months with nivolumab vs. 3.9 months in the chemotherapy arm,” he said. “Notably, 21% of patients in the nivolumab arm were still in response, compared to only 6% in the chemotherapy arm.”
Patients enrolled in the open label study had unresectable advanced or recurrent ESCC refractory or intolerant to one prior fluoropyrimidine/platinum-based therapy. They were randomized 1:1 to receive 240 mg of nivolumab every 2 weeks or investigators’ choice of paclitaxel or docetaxel.
Fewer treatment-related adverse events (TRAEs) were reported with nivolumab, Dr. Cho said.
Any grade TRAEs occurred in 66% vs. 95% of patients in the groups, respectively, and grade 3-4 TRAEs occurred in 18% vs. 63%. The majority of select TRAEs – defined as those with potential immunologic etiology, including endocrine, gastrointestinal, hepatic, pulmonary, renal, and skin effects – were grade 1 or 2, and the only difference between the nivolumab and chemotherapy groups with respect to those was in endocrine effects, which affected 11% vs. less than 1% of patients, respectively.
Grade 3/4 select TRAEs occurred in less than 2% of patients, Dr. Cho noted.
An exploratory analysis further showed significant overall improvement in health-related quality of life with nivolumab through week 42 on treatment, he added.
The findings are of note, because metastatic esophageal cancer has a 5-year relative survival rate of less than 8%, and ESCC accounts for about 90% of cases worldwide, he said, adding that current second-line chemotherapy options for ESCC offer poor long-term survival and are associated with toxicity.
Nivolumab, which showed promising antitumor activity and manageable toxicity for advanced ESCC in patients who were refractory to or intolerant of standard chemotherapies in the phase 2 ATTRACTION-1 study, is the first immune checkpoint inhibitor to demonstrate a statistically significant, clinically meaningful improvement in OS vs. chemotherapy in this setting, he said.
The findings of this final analysis of ATTRACTION-3, which shows a 23% reduction in the risk of death, a 2.5-month improvement in median OS, benefit across PD-L1 subgroups, and a favorable safety profile, suggest that nivolumab represents a new standard second-line treatment option for patients with advanced ESCC, he concluded.
ATTRACTION-3 was funded by Ono Pharmaceutical Co., in collaboration with Bristol-Myers Squibb. Dr. Cho reported relationships with Bristol-Myers Squibb, Ono Pharmaceutical, and others. He also reported stock ownership and/or patents with TheraCanVac and Champions Oncology.
SOURCE: Cho B et al. ESMO 2019, Abstract LBA11.