Osimertinib/Savolitinib Combo Shows Promise in NSCLC

SAN DIEGO — Combination therapy with osimertinib and savolitinib could become a novel first-line treatment option for patients with de novo MET-aberrant, EGFR-mutated advanced non–small cell lung cancer (NSCLC), according to results of the phase 2 FLOWERS study.

Compared with EGFR inhibitor osimertinib alone, the combination demonstrated a clinically meaningful improvement in the objective response rate — the study’s primary endpoint — with a positive trend in progression-free survival and a manageable safety profile.

About 30% patients with EGFR-mutated NSCLC fail to respond well to EGFR-tyrosine kinase inhibitors (TKIs), explained Jin-Ji Yang, MD, with Guangdong Lung Cancer Institute, Guangzhou, China, who reported the study results at the World Conference on Lung Cancer (WCLC) 2024.

Data suggested that de novo MET amplification occurs in up to 5% patients with treatment-naive EGFR-mutated advanced NSCLC, and MET overexpression occurs in up to 15% these patients.

Coexistence of EGFR mutation and MET amplification/overexpression reduces sensitivity to EGFR-TKI therapy “and is likely the mechanism for mediating primary resistance to first-line EGFR-TKI monotherapy,” Yang explained in her presentation.

Osimertinib is a third-generation EGFR-TKI recommended as the first-line treatment for EGFR-mutant advanced NSCLC. Savolitinib is a highly selective MET-TKI which has demonstrated antitumor activity in various cancers with MET alterations.

The FLOWERS study is the first to test whether combining the two agents could improve efficacy and overcome MET-driven primary resistance in these patients.

The phase 2 study enrolled 44 treatment-naive patients with de novo MET-aberrant, EGFR-mutant, stage IIIB-IV NSCLC; 23 were randomly allocated to receive oral osimertinib (80 mg once daily) alone and 21 to receive oral osimertinib (80 mg once daily) plus savolitinib (300 mg twice daily).

At a median follow-up of 8.2 months, the objective response rate was 60.9% with osimertinib monotherapy vs 90.5% with combination therapy. The disease control rate was also better with the combination therapy than with monotherapy (95.2% vs 87%).

Median duration of response (not yet mature) was 8.4 months with monotherapy vs 18.6 months with combination therapy.

Preliminary progression-free survival data also showed a trend in favor of combination therapy over monotherapy (a median of 19.3 vs 9.3 months; hazard ratio, 0.59).

Most treatment-related adverse events were grade 1 or 2, and there were no fatal adverse events.

Treatment-related adverse events of grade 3 or higher were more common with combination therapy (57.1% vs 8.7%). The most common events with monotherapy were diarrhea (56.5%), rash (52.2%), and pruritus (43.5%) and with dual therapy were rash (52.4%), thrombocytopenia (52.4%), and peripheral edema (42.9%).

The results showed that the combination therapy has the potential to become a first-line treatment option for patients who do not respond well to EGFR-TKIs alone, said Yang, in a press release.

Discussant for the study Paul Paik, MD, thoracic oncologist at Memorial Sloan Kettering Cancer Center in New York City, said this study “adds to data suggesting high MET expression might be a poor prognostic or predictive marker, the outcomes of which are improved with MET inhibition.”

He cautioned, however, that there appears to be “quality of life, side-effect trade-offs with dual MET plus EGFR TKI upfront.”

Paik said he looks forward to results from FLOWERS on serial circulating tumor DNA and formal androgen receptor testing, which “might aid in further assessing clonality and characterizing MET as a co-driver in this setting.”

The study was funded by AstraZeneca China. Yang had no disclosures. Paik disclosed relationships with EMD Serono, Bicara, Novartis, and Summit.