While nivolumab plus doublet chemotherapy was effective in extensive-stage small-cell lung cancer (ES-SCLC) in a recent randomized trial, the results might not be sufficient to change current clinical practice, in which two first-line chemo-immunotherapies are already approved and recommended, sources said.
Nivolumab added to platinum/etoposide doublet chemotherapy was well tolerated and significantly improved progression-free survival (PFS) and overall survival (OS) compared to chemotherapy alone, according to results of ECOG-ACRIN EA5161, a randomized, phase 2 trial including 160 patients with ES-SCLC.
Risks of progression and death were reduced by 32% and 27%, respectively, when the immune checkpoint inhibitor was given along with chemotherapy, according to data presented by investigator Ticiana A. Leal, MD, of the University of Wisconsin Carbone Cancer Center in Madison.
“Our study, EA5161, confirms the efficacy of nivolumab in extensive-stage small cell lung cancer,” Dr. Leal said in a presentation she gave as part of the American Society of Clinical Oncology virtual scientific program.
Nivolumab did demonstrate a clear PFS advantage in EA5161, but “more surprisingly for a small trial” it also showed a clear OS advantage, said Taofeek K. Owonikoko, MD, PhD, in a commentary on the study.
“While the study as currently reported is insufficient to change practice, it does however provide very strong data to make the combination of nivolumab and platinum doublet acceptable as a platform for future clinical trials,” he said in the commentary, which was also included in the virtual ASCO proceedings.
Going forward, it would be difficult to justify another nondefinitive randomized phase 2 chemo-immunotherapy trial, especially if there are no “immediate plans” for a confirmatory phase 3 trial, added Dr. Owonikoko, who is director of thoracic oncology at Winship Cancer Institute of Emory University in Atlanta.
Nivolumab wasn’t the only immune checkpoint with new first-line data in ES-SCLC at ASCO. In the randomized, double-blind, phase 3 KEYNOTE-604 trial, pembrolizumab added to etoposide and platinum significantly prolonged PFS and showed a trend toward improved OS. However, the significance threshold for OS was missed, according to the report.
While these pembrolizumab data are also insufficient to change today’s practice standards, results for both the pembrolizumab- and nivolumab-containing regimens are nevertheless compelling to support their use as a platform for new treatment strategies, according to Dr. Owonikoko.
With these new ASCO data, there are now randomized data confirming a benefit of immune checkpoint inhibitor–based regimens in ES-SCLC, according to Lauren A. Byers, MD, from the department of thoracic/head and neck medical oncology at The University of Texas MD Anderson Cancer Center in Houston.
Immune checkpoint inhibitors that are approved by the Food and Drug Administration for first-line treatment of ES-SCLC include atezolizumab (in combination with carboplatin and etoposide) and durvalumab (in combination with either carboplatin or cisplatin plus etoposide). In current National Comprehensive Cancer Network (NCCN) guidelines, both are described as “preferred” regimens for primary or adjuvant therapy.
“A lot of times in oncology we have trials with similar drugs, and you get somewhat different answers in terms of the outcome of the trials, so we’re kind of trying to tease them apart,” Dr. Byers said in an interview.
“I think in this situation, we’ve got four studies, and they essentially are extremely similar in terms of the result, which just gives us even more confidence that there is benefit, at least for a subset of patients.”
The EA5161 study was developed to evaluate the role of nivolumab in ES-SCLC, Dr. Leal said in her virtual ASCO presentation.
Of the 160 patients enrolled and randomized, 145 were eligible and treated, including 75 in the nivolumab plus chemotherapy arm and 70 in the chemotherapy arm. Participants were evenly split between performance status 0 and 1, and little more than half of patients were women, and a median of five treatment cycles were delivered in each arm.
Median PFS, the primary end point of the trial, was 5.5 months for nivolumab plus chemotherapy versus 4.7 months for chemotherapy alone for all eligible and treated patients (hazard ratio, 0.68; 95% confidence interval, 0.48-1.00; P = .047). In the intent-to-treat population, median PFS was 5.5 and 4.6 months in the respective arms (HR, 0.65; 95% CI, 0.46-0.91; P = .012).
Median overall survival was 11.3 months and 9.3 months for the nivolumab plus chemotherapy and chemotherapy-only arms, respectively, for all eligible and treated patients (HR, 0.73; 95% CI, 0.49-1.1), and in the intent-to-treat population, median OS was 11.3 and 8.5 months for the respective arms (HR, 0.67; 95% CI, 0.46-0.98; P = .038).
The overall response rate was 52% for nivolumab plus chemotherapy and 47% for chemotherapy alone, with a median duration of response of 5.6 and 3.3 months, respectively, Dr. Leal reported.
Treatment was generally well tolerated in both arms, according to the investigator, with no safety signals observed. Toxicities resulting in death occurred in nine patients in the nivolumab plus chemotherapy arm and seven in the chemotherapy-only arm. “Most of the events were related to progression of disease,” Dr. Leal said.
While nivolumab and pembrolizumab’s use in the first-line setting may be uncertain, it is currently approved for metastatic SCLC that has progressed following platinum-based chemotherapy and at least one more line of therapy, according to the drug’s package insert.
The EA5161 study was sponsored by the National Cancer Institute. Dr. Leal provided disclosures related to AbbVie, AstraZeneca, Bayer, BeyondSpring, Bristol-Myers Squibb, Genentech, InvisionFirst Lung, Merck, Mirati, Novocure, and Takeda.
Dr. Owonikoko provided disclosures related to Bristol-Myers Squibb, Novartis, Celgene, Lilly, Sandoz, AbbVie, Eisai, and Takeda, among others. Dr. Byers reported disclosures related to Bristol-Myers Squibb, AstraZeneca, AbbVie, GenMab, PharmaMar, and Sierra Oncology, Tolero, Alethia, Merck, Jazz Pharmaceuticals, and Pfizer.
SOURCE: Leal TA et al. ASCO 2020, Abstract 9000.