In a phase 2 cohort study, who had previously been treated with platinum-based chemotherapy and immune therapy.
Adagrasib targets KRAS (G12C), which had long been thought undruggable until research published in 2013 revealed a new binding pocket that did not compete directly against the protein’s natural binding partner. The new trial further validates the approach. “It supports that clinically effective targeted therapies can be developed for patients with KRAS (G12C)–mutant NSCLC,” said Pasi Jänne, MD, PhD, who is the lead author of the study describing the new results published online in the New England Journal of Medicine.
KRAS is the most frequently mutated oncogene in human cancers. A mutated form is found in about 25% of NSCLCs. KRAS plays a key role in cell signaling governing growth, maturation, and cell death. The mutated form is linked to cancer growth and spread. Patients with mutated KRAS have few effective treatment options.
Adagrasib is currently under study and not yet approved by the Food and Drug Administration. However, sotorasib (Lumakras, Amgen), which also inhibits KRAS (G12C), was approved in May 2021 by the FDA for KRAS (G12C)–mutated NSCLC. There are some key differences between the drugs. Adagrasib has a half-life of 23 hours versus 5 hours for sotorasib, and the newer drug has the potential to penetrate the central nervous system. That could be an important consideration in NSCLC since it often metastasizes to the brain. “Having pharmacological approaches to treat brain metastases is a wonderful new therapeutic option for lung cancer patients,” said Dr. Jänne, who is director of the Lowe Center for Thoracic Oncology at Dana Farber Cancer Institute, Boston.
Adagrasib is being investigated as part of the KRYSTAL-1 study, alone and as part of combinations in various solid tumors. Previously treated NSCLC KRAS (G12C) patients are also being enrolled in a phase 3 study of adagrasib combined with docetaxel, as well as another phase 2 study of adagrasib combined with pembrolizumab as first-line therapy for NSCLC KRAS (G12C).
Adagrasib is likely to remain a second-line therapy following chemotherapy and immunotherapy. “The activity by itself at the moment is not sufficient to be a first-line treatment. That may change in the future in combination with a standard of care agent or in a subset of patients with KRAS (G12C)–mutant NSCLC, although no subset with higher efficacy has been identified to date. Identification of predictive biomarkers for patients likely to benefit from single agent or an adagrasib combination treatment remains a high priority,” Dr. Jänne said.
The study included 116 patients who had previously been treated with platinum-based chemotherapy and anti–programmed death 1 or programmed death–ligand 1 therapy. They received 600 mg oral adagrasib twice per day over a median follow-up period of 12.9 months. About 42.9% (95% confidence interval, 33.5%-52.6%) experienced a confirmed objective response with a median duration of 8.5 months (95% CI, 6.2-13.8 months). The median progression-free survival was 6.5 months (95% CI, 4.7-8.4 months). After a median follow-up of 15.6 months, the median overall survival was 12.6 months (95% CI, 9.2-19.2 months). The estimated overall survival at 1 year was 50.8% (95% CI, 40.9%-60.0%).
33 patients had stable central nervous system metastases that had been previously treated. About 33.3% had an intracranial confirmed objective response (95% CI, 18.0-51.8%) with a median duration of response of 11.2 months (95% CI, 2.99 months to not available).
Adverse events are similar to what is seen with other targeted therapies, according to Dr. Jänne. 97.4% of patient reported a treatment-related adverse event; 52.6% had grade 1-2 adverse events, and 44.8% had grade 3 adverse events. 6.9% discontinued the drug as a result.
Dr. Jänne has consulted for Mirati Therapeutics and is a member of its scientific advisory board. The study was funded by Mirati Therapeutics.