On Monday, GSK.L announced that the late-stage trial assessing the combination of its cancer drugs Zejula and Jemperli as maintenance treatment for a specific type of endometrial cancer has achieved its primary objective.
The trial demonstrated that the regimen of Jemperli plus chemotherapy followed by Jemperli and Zejula significantly enhanced progression-free survival as opposed to chemotherapy alone. This positive outcome was observed in both the overall patient population and a subgroup with specific tumor types.
Progression-free survival, indicating the duration a patient lives without disease progression post-treatment, exhibited a “statistically significant and clinically meaningful” benefit, as reported by GSK. The trial’s success is a notable advancement for the British pharmaceutical company, which has been working to revitalize its oncology business. Jemperli had previously received approval in the U.S. and the U.K. for treating specific subtypes of aggressive or recurrent endometrial cancer in conjunction with chemotherapy.
In terms of revenue in 2022, Zejula holds the position of GSK’s most significant cancer drug, contributing to approximately 77% of the £602 million ($763.8 million) generated by its oncology business.
GSK is actively analyzing the complete trial data, including the crucial secondary endpoint of overall survival, with further details expected to be disclosed as the analysis progresses.
Hesham Abdullah, Oncology R&D Team Lead, remarked, “Today’s positive topline results reinforce our approach of building combination therapies with [Jemperli] as the backbone in an effort to improve patient outcomes and options.”
Prior to the declaration, in July, GSK secured FDA approval for Jemperli and chemotherapy—excluding Zejula—for the treatment of mismatch repair deficient (dMMR) or microsatellite instability-high (MSI-H) endometrial cancer. The initial segment of the RUBY trial unveiled that Jemperli and chemotherapy significantly reduced the risk of progression or death by over 70% as opposed to just chemotherapy in dMMR/MSI-H endometrial cancer.
During the first phase of the RUBY trial, patients underwent treatment with Jemperli and chemotherapy, followed by Jemperli as a standalone therapy. In the second phase, Zejula was introduced alongside Jemperli exclusively during the maintenance phase.
The substantial progression-free survival advantage observed in the initial part of the study underscores the efficacy of PD-1/L1 inhibitors like Jemperli across various types of dMMR/MSI-H tumors. This outcome also leaves minimal opportunity for GSK to enhance outcomes further in this patient cohort by incorporating Zejula into the treatment regimen.
The extent of improvement was nearly identical, reaching nearly 60%, for a combination that involves AstraZeneca (AZ) and Merck’s PARP inhibitor Lynparza.
In contrast, within the pMMR subgroup, the introduction of Lynparza amplified the 23% progression-free survival advantage from the Imfinzi-chemo combination to 43%.
GSK mentioned that findings from the ongoing RUBY part 2 analysis will be presented to regulatory authorities. Information regarding whether the Zejula combination prolonged the lives of patients is still in the preliminary stages, and researchers are actively monitoring patients to gather that data, as per the company’s statement.
