GlaxoSmithKline (GSK) has announced positive results from its Phase II PERLA trial, a head-to-head comparison between its PD-1 inhibitor Jemperli (dostarlimab) and Merck & Co’s PD-1 inhibitor Keytruda (pembrolizumab) for first-line treatment of metastatic non-small cell lung cancer (NSCLC) without an actionable mutation. In this double-blind trial, 243 patients were randomly assigned to receive either Jemperli in combination with chemotherapy or standard-of-care Keytruda in combination with chemotherapy.

The trial has met its primary endpoint of objective response rate (ORR), but as it was not designed to demonstrate superiority, it remains to be seen whether Jemperli outperformed Keytruda or demonstrated non-inferiority. There were no new safety signals reported for Jemperli, with the toxicity profile consistent with other trials investigating this therapeutic agent. Full results from this trial are expected to be announced at an upcoming scientific meeting.

In addition, following the recommendation of the Independent Data Monitoring Committee, GSK is advancing both arms of its Phase II/III COSTAR trial. The trial has met its pre-specified expansion criteria, enabling progression into Phase III. The trial is an open-label, three-arm trial evaluating the safety and efficacy of cobolimab, an anti-TIM-3 monoclonal antibody, in combination with Jemperli and docetaxel versus Jemperli and docetaxel, or docetaxel alone, in 750 NSCLC patients without an actionable mutation who have progressed on prior anti-PD 1/PD-L1 therapy.

There is currently no approved use of an immune checkpoint inhibitor (ICI) in patients who have progressed on or following ICI therapy, making this an area of intense research for pharma companies. The TIM-3 receptor has been identified as a negative regulator of T cells, with activity driving T cells into exhaustion and terminal dysfunction. TIM-3 is regulated and expressed alongside other immune checkpoint receptors, including PD-1, LAG-3 and TIGIT. Dual checkpoint inhibition is proposed as a mechanism for increasing the number and duration of ICI responses, as well as generating a new anti-tumour immune response following relapse.

Jemperli and cobolimab, originally owned by Tesaro , became GSK assets in 2019 when TESARO was acquired in a deal worth $5.26bn. To date, Jemperli has only been approved for mismatch repair-deficient endometrial cancer, lagging behind competitors such as Keytruda, Bristol Myers Squibb’s Opdivo (nivolumab) and Roche’s Tecentriq (atezolizumab), which have gained approvals across multiple oncology indications. Keytruda currently dominates over other ICIs in the NSCLC setting, with eight major market (8MM*) sales forecast to peak at $7.9bn in 2028. With ICI sales in the 8MM predicted to reach $18.2bn in the NSCLC setting by 2028, positive results from the PERLA trial could mean Jemperli gains sales in this lucrative sector.

The potential for Jemperli in the first-line setting depends on its comparison with Keytruda. Demonstrating equivalent efficacy alone may not be enough for Jemperli to obtain significant sales in this highly competitive disease setting, as physician familiarity and a well-understood toxicity profile are likely to make Keytruda more favourable. In contrast to the fierce competition between ICI regimens in early lines of NSCLC therapy, there is little competition in the market for checkpoint-exposed patients. If the Phase III COSTAR trial were to meet its endpoints and demonstrate the combination of Jemperli, cobolimab and docetaxel to be efficacious in checkpoint-exposed patients, this would be a huge win for GSK.

*8MM – US, France, Germany, Italy, Spain, UK, Japan and Urban China