Cancer risk scuppers Kyowa Kirin's autoimmune disease drug

Kyowa Kirin has terminated all clinical trials of its anti-OX40L antibody rocatinlimab, after cases of cancer were seen in patients taking the drug.

The drug – which is in the same class as Sanofi's late-stage rival amlitelimab – was being tested in a series of inflammatory indications, including atopic dermatitis (AD), prurigo nodularis, and asthma.

According to the Japanese drugmaker, there was one confirmed case and one suspected case of Kaposi's sarcoma, adding to an earlier case of the cancer, which is associated with reactivation of a herpes virus in people with weakened immune systems, such as those with HIV infection.

The two new cases come after another previously confirmed case, and according to Kyowa Kirin, suggest "a potential mechanistic link to OX40 pathway modulation" and a "plausible biological concern that cannot be excluded."

The decision comes just a few weeks after Kyowa Hakko's development partner for the programme, Amgen, returned all rights to the drug. Amgen had licensed rights to the candidate in 2021 in a deal that included an upfront payment of $400 million and milestones worth up to $850 million.

Just last month, Kyowa Kirin was committed to taking the programme forward, saying it was hoping to start filing rocatinlimab for approval as a treatment for AD, its lead indication, in the first half of 2026, and was preparing to self-market the drug in the US.

The decision adds to a sense that OX40-targeted drugs will not live up to their initial expectations. Last September, shares in Sanofi came under pressure when it reported the results of a phase 3 trial of amlitelimab in AD – even though it met its primary efficacy objectives – and earlier this year another trial missed its main endpoint.

Amlitelimab has been billed by Sanofi as a successor to its Regeneron-partnered, $18.3 billion blockbuster Dupixent (dupilumab), and as the clinical results have fallen short of expectations, some analysts have downgraded their sales expectations for the drug and suggest it would likely be limited to later-line use. The French drugmaker has since said it will press ahead with regulatory filings.

Kyowa Kirin's president and chief operating officer, Abdul Mullick, said the decision to terminate the programme is "deeply disappointing news, as we had hoped to bring a safe and effective treatment to patients."

He added: "Rocatinlimab has demonstrated durable and clinically meaningful efficacy in moderate-to-severe atopic dermatitis in the ROCKET programme. However, the safety profile has evolved, and as patient safety remains our highest priority, we have taken this decisive and cautious step."

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