Kelun's MSD-partnered TROP2 drug gets first okay in China

Kelun-Biotech has become the second drugmaker to bring a TROP2-directed antibody-drug conjugate to regulatory approval, getting a green light in China for sacituzumab tirumotecan (sac-TMT).

The National Medical Products Administration (NMPA) has cleared the drug for triple-negative breast cancer (TNBC), making it the first direct competition in the market for Gilead Sciences' Trodelvy (sacituzumab govitecan), which was cleared in China for TNBC in 2022.

The approval means Kelun has brought its TROP2 ADC to market ahead of AstraZeneca and Daiichi Sankyo's datopotamab deruxtecan (Dato-DXd), whose FDA filing in non-small cell lung cancer (NSCLC) was withdrawn earlier this month after it became clear the US regulator did not find the data with the drug compelling.

In China, sac-TMT has been cleared to treat adults with unresectable, locally advanced or metastatic TNBC who have received at least two prior systemic therapies – the same indication granted to Trodelvy. It will still need pricing and reimbursement approval before it can launch.

Kelun said sac-TMT is the first domestically developed ADC fully approved for marketing in China.

It is also under review by the NMPA for locally advanced or metastatic EGFR-mutant NSCLC, for second-line use after either an EGFR inhibitor or EGFR drug and chemotherapy – an indication that would put it in direct contention with Dato-DXd after AZ and Daiichi's was re-filed for EGFR-positive NSCLC only.

Outside China, MSD has rights to sac-TMT under the terms of a partnership signed in 2022, which involved a $17 million upfront payment and could be worth up to $1.4 billion.

While the identity of the partnered programme was kept under wraps at the time, it was subsequently revealed to be the TROP2 ADC, with analysts noting that it could serve as a companion to MSD's immuno-oncology blockbuster Keytruda (pembrolizumab).

Later in 2022, MSD expanded the alliance to cover seven ADC candidates, with a potential value of $9.3 billion – assuming all seven make it through to market and hit sales targets.

The TNBC approval for sac-TMT in China is based on the results of the phase 3 OptiTROP-Breast01, revealed at this year's ASCO congress, which showed that treatment with sac-TMT led to a 47% reduction in the risk of death compared to physician's choice of treatment.

The study involved only Chinese patients, so would not be suitable for marketing applications in the US. It's worth noting, however, that MSD is focusing its development efforts for the drug in the US as an adjuvant therapy for TNBC, whilst also testing it in other types of cancer including gastric, cervical, and endometrial cancers as well as NSCLC.