GSK/Merck's hopeful bintrafusp alfa fails in key lung cancer trial

GlaxoSmithKline’s big gamble on a cancer drug developed by Germany’s Merck KGaA looks unlikely to pay out, after bintrafusp alfa failed to outperform US-based Merck & Co’s Keytruda in a lung cancer trial.

GSK had high hopes in 2019 that Merck KGaA’s bintrafusp alfa could be a substantial addition to a pipeline that was in need of attention, paying more than $4.2 billion for the cancer immunotherapy in early 2019.

GSK secured co-development and co-marketing rights to the bifunction fusion protein, an anti-PD-L1/TGF beta trap for solid tumours including lung cancer.

The companies were so confident in the bispecific antibody that they began trialling it against Merck & Co’s blockbuster immunotherapy in first line lung cancer.

This is the most lucrative indication that has allowed Keytruda to establish a foothold as the most successful cancer immunotherapy on the market.

German Merck and GSK were testing the drug in patients with stage IV non-small cell lung cancer, with high expression of the PD-L1 biomarker, a mutation that tends to make tumours more susceptible to immunotherapy.

But an Independent Data Monitoring Committee has said the trial dubbed INTR@PID Lung 037 should be halted.

Merck agreed, confirming the halt after admitting that the trial looks unlikely to meet its efficacy endpoint.

Although development is continuing in other forms of cancer, the results cast doubt on the future of the drug formerly known as M7824.

It also means that German Merck is set to miss out on some hefty “biobucks” milestone payments due from GSK under the terms of the deal, which began with a €300 million ($363 million) payment upfront.

There was another €500 million ($605m) tied to the lung cancer development programme, plus up to €2.9bn ($3.5bn) in development and commercial milestones.

The deal came off the back of phase 1 results announced at the 2018 European Society for Medical Oncology (ESMO) conference.

The data showed a much higher response rate with bintrafusp alfa in patients with NSCLC than would be expected with first-generation PD-1/PD-L1 inhibitors such as Keytruda (pembrolizumab).