Abbisko Therapeutics has received fast track designation from the US Food and Drug Administration (FDA) for its CSF-1R inhibitor pimicotinib (ABSK021) to treat tenosynovial giant cell tumour (TGCT). 

Pimicotinib is an orally available, highly selective small molecule for use in patients with TGCT who are not amenable to surgical procedures. 

In January 2023, the product received breakthrough therapy designation from the FDA.

The company expects that the designations will expedite the development and marketing of the CSF-1R inhibitor worldwide.

It also received BTD and priority medicine (PRIME) status from China's National Medical Products Administration (NMPA) and from the European Medicines Agency.

An international Phase III clinical trial of the treatment is underway in TGCT patients in the US, Europe, China and Canada.

One year follow-up data from a Phase Ib trial in TGCT patients showed that treatment with once-daily 50mg pimicotinib offered an 87.5% objective response rate (ORR). 

Abbisko is also analysing pimicotinib to treat other solid tumour types.

The company received NMPA approval for a Phase II trial in chronic graft-versus-host disease and advanced pancreatic cancer patients.

The latest development comes after Abbisko Therapeutics signed an agreement with Merck KGaA to commercialise pimicotinib for a range of indications.

The licensed territories included are the Chinese mainland, Hong Kong, Macau and Taiwan.

Abbisko will retain exclusive rights for developing pimicotinib in these territories.

Abbisko is entitled to receive a $70m down payment from MerckKGaA.

Abbisko is eligible to receive another option exercising payment when Merck KGaA exercises the global marketing option. 

The Merck KGaA-Abbisko deal totals $605.5m in upfront, option exercising, development and commercialisation milestone payments in addition to royalties on annual net product sales.