SAN FRANCISCO – When used as first-line therapy for renal cell carcinoma (RCC), the combination of pembrolizumab and axitinib has similar safety and better efficacy than single-agent sunitinib, the current standard of care, according to findings of the KEYNOTE-426 trial that will be reported at the 2019 Genitourinary Cancers Symposium sponsored by the American Society for Clinical Oncology, the American Society for Radiation Oncology, and the Society of Urologic Oncology.
“Axitinib is usually licensed and usually used in sunitinib-refractory disease. However, there is data for both pembrolizumab and axitinib in the frontline setting,” said lead author, of Barts Health and the Royal Free NHS Trusts, Barts Cancer Institute, and Queen Mary University of London. A phase 1b trial testing the combination showed an impressive 73% objective response rate and acceptable toxicity ( ), prompting further investigation.
The 861 patients in KEYNOTE-426, a phase 3, randomized, controlled trial, were evenly assigned to combination therapy with the immune checkpoint inhibitor pembrolizumab (Keytruda), which targets programmed death–1, plus the tyrosine kinase inhibitor axitinib (Inlyta), which targets vascular endothelial growth factor and platelet-derived growth factor, or to monotherapy with the tyrosine kinase inhibitor sunitinib (Sutent), which also targets those growth factors.
Main results reported in a presscast held before the symposium showed that, with a median follow-up of 12.8 months, pembrolizumab-axitinib reduced the risk of progression-free survival events by a relative 31% and the risk of death by a relative 47%, compared with sunitinib. The combination had a rate of grade 3-5 treatment-related adverse events similar to the rate with sunitinib alone.
“The benefit of pembrolizumab plus axitinib was seen irrespective of IMDC [International Metastatic Renal Cell Carcinoma Database Consortium] risk group or PD-L1 [programmed death–ligand 1] status,” Dr. Powles noted. “Pembrolizumab and axitinib should be a standard of care in this setting, in my opinion.”
“This is a very significant trial, and it’s going to impact on patient management going forward, as it works through the regulatory process,” commented ASCO Expert and presscast moderator, who is also deputy director and associate director of clinical research at the University of Virginia Cancer Center and a professor of medicine and urology at the University of Virginia, Charlottesville.
Patients in KEYNOTE-426 had newly diagnosed or recurrent stage IV clear cell RCC and had not received any previous systemic treatment for their advanced disease. They were randomized to pembrolizumab (200 mg intravenously every 3 weeks up to 35 cycles) plus axitinib (5 mg orally twice daily), or to sunitinib (50 mg orally once daily for first 4 weeks of each 6-week cycle).
Median overall survival was not reached in either group, but the 12-month rate was 89.9% with pembrolizumab-axitinib versus 78.3% with sunitinib, Dr. Powles reported in the presscast. The difference corresponded to a near halving of the risk of death with the combination (hazard ratio, 0.53; P less than .0001).
Median progression-free survival was 15.1 months with pembrolizumab-axitinib and 11.1 months with sunitinib. The difference corresponded to a nearly one-third reduction in the risk of events with the combination (HR, 0.69; P = .0001). “The 11.1 months is quite long for a control arm, so there’s nothing from these data to suggest that sunitinib underperformed in this trial,” he noted.
Pembrolizumab-axitinib was also associated with a higher objective response rate (59.3% vs. 35.7%; P less than .0001). The median duration of response was not reached with the former, compared with 15.2 months with the latter.
“Pembrolizumab and axitinib had a manageable safety profile,” Dr. Powles said. The rate of grade 3-5 treatment-related adverse events was 62.9% with the combination and 58.1% with sunitinib monotherapy.
The rate of events leading to death was similar at 0.9% and 1.6%, respectively. The rate of events leading to discontinuation of any treatment was 25.9% for pembrolizumab-axitinib and 10.1% for sunitinib, and the rate of events leading to discontinuation of both drugs in the combination was 8.2%.
Dr. Powles reported that he has a consulting or advisory role with Genentech/Roche, Bristol-Myers Squibb, Merck, Novartis, and AstraZeneca; has a nonspecified relationship with Ipsen and Bristol-Myers Squibb; receives honoraria from Roche/Genentech, Bristol-Myers Squibb, and Merck; and receives research funding from Astra-Zeneca/MedImmune and Roche/Genentech. The study was funded by Merck.
SOURCE: Powles T et al. GUCS 2019, .