Lilly nets Scorpion cancer drug in $2.5bn licensing deal

Eli Lilly has unveiled a $2.5 billion deal to acquire rights to a cancer therapy being developed by Scorpion Therapeutics in a third major transaction announced on the first day of the JP Morgan healthcare conference.

The pharma group did not break down the details of the license to get control of STX-478, described as a next-generation PI3K alpha inhibitor for breast cancer and other advanced solid tumours, but confirmed the $2.5 billion figure – in cash – includes an undisclosed upfront payment and regulatory and sales milestones.

STX-478 is currently in a phase 1/2 trial in patients with locally advanced or metastatic hormone receptor-positive, HER2-negative breast cancer and other solid tumours driven by PI3K alpha mutations, both as a monotherapy and in combination with CDK4/6 inhibitors and AstraZeneca's selective oestrogen receptor degrader Faslodex (fulvestrant).

If the deal goes through, Scorpion will spin its non-PI3K pipeline assets – which include a pair of EGFR inhibitors codenamed STX-721 and STX-241 – into a new, as-yet-unnamed independent company that will be majority-owned by Scorpion's current shareholders with Lilly retaining a minority stake.

In a statement, Lilly said that STX-478 has the potential to be a new generation of PI3K-targeting agents as it selectively binds to a pathway that is present in malignant cells, but absent in healthy cells. That could make it easier to tolerate, with fewer off-target side effects, than current drugs in the class.

The first PI3K inhibitor to reach the US market for a breast cancer indication was Novartis' Piqray/Vijoice (alpelisib), cleared in 2019 as a second-line therapy alongside fulvestrant for patients with advanced HR-positive, HER2-negative breast cancer with a PIK3CA mutation whose cancer has progressed on or after endocrine-based therapy.

It was joined last year by Roche's Itovebi (inavolisib), the company's second candidate after its lead drug in the class (taselisib) was abandoned on safety grounds.

Other drugs in the PI3K class are on the market for haematological cancers, but as a whole the group is known to carry a risk of serious side effects including infections, diarrhoea, liver damage, skin problems, and lung inflammation.

According to Lilly, STX-478 could potentially address 30%-40% of people with HR-positive breast cancer, with a profile that could allow it to be used more readily in combination with other therapies.

Those combinations could "potentially deliver meaningful impact in earlier treatment settings when there is the best opportunity to improve outcomes for patients," commented Jacob Van Naarden, head of Lilly Oncology.

The agreement isn't Lilly's first attempt to make a mark in the PI3K inhibitor class, having previously been working on LOXO-783, a drug it acquired as part of its $8 billion takeover of Loxo Oncology in 2019, but jettisoned last year after concluding it would not be sufficiently competitive with its rivals. Loxo was co-founded by Keith Flaherty, who also set up Scorpion.

There's no shortage of other candidates coming through the pipeline, with Relay Therapeutics, Faeth Therapeutics, Junshi Bio, Jiangsu Hansoh, and BridgeBio at or near the clinical testing stage.

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