Merck Group Secures Global Rights to Abbisko's Promising CSF-1R Inhibitor

In a significant move that highlights the growing interest in CSF-1R inhibitors, Germany's Merck Group has expanded its partnership with Shanghai-based Abbisko Therapeutics. The pharmaceutical giant has paid $85 million to acquire global rights for pimicotinib, a drug showing promise in the treatment of tenosynovial giant cell tumors (TGCTs).

Expanding Partnership and Financial Details

Merck Group's latest investment builds upon a previous deal struck in 2023, where the company paid $70 million for commercialization rights in Greater China. The expanded agreement puts Abbisko in line for potential payments totaling up to $605.5 million, including upfront fees, development milestones, and commercial milestones. Additionally, Abbisko stands to receive a share of royalties should pimicotinib reach the market.

Promising Clinical Results

The decision to secure global rights follows encouraging results from a phase 3 trial of pimicotinib in TGCT patients. The study, reported in November, demonstrated a significant improvement in response rates:

• 54% of patients treated with pimicotinib showed a response at 25 weeks
• Only 3.2% of patients in the placebo group exhibited a response

These results underscore the potential of pimicotinib as a valuable treatment option for TGCT patients worldwide.

Competitive Landscape in CSF-1R Inhibition

Merck Group's investment in pimicotinib places the company in direct competition with other pharmaceutical firms developing CSF-1R inhibitors:

1. Daiichi Sankyo's Turalio (pexidartinib): Approved by the FDA in 2019 for TGCTs, Turalio generated sales of 5.1 billion Japanese yen (approximately $33 million) in the last nine months of 2024, representing a 25% year-over-year increase.

2. Ono Pharmaceutical's vimseltinib: Recently approved by the FDA for TGCT treatment, adding another player to the market.

As the CSF-1R inhibitor space heats up, Merck Group's global rights to pimicotinib position the company to potentially capture a significant share of this emerging market.