FDA Approves PIMJETMI With Abbisko Milestone Tied to U.S. Sale

EMD Serono announced on November 10, 2026, that the U.S. Food and Drug Administration had approved PIMJETMI (pimicotinib) for adults with symptomatic tenosynovial giant cell tumor (TGCT) for which surgical resection may cause worsening functional limitation or severe morbidity. The once-daily oral drug also sets up a new payment for developer Abbisko Therapeutics: an additional milestone upon the first U.S. commercial sale.

Abbisko independently developed the small-molecule colony-stimulating factor 1 receptor (CSF-1R) inhibitor and granted global commercialization rights to Merck KGaA (MRK.DE ), Darmstadt, Germany, which operates its U.S. and Canadian healthcare business as EMD Serono. In Abbisko’s November 11, 2026 announcement, founder and chief executive officer Yao-Chang Xu called PIMJETMI “our first proprietary innovative medicine to reach commercialization.”

A Global License Defines the Economics

The December 2023 licensing agreement initially gave Merck exclusive commercialization rights in mainland China, Hong Kong, Macau and Taiwan, together with an option for worldwide rights. Merck exercised that option in March 2025, securing the exclusive worldwide commercialization license.

Abbisko received a $70 million upfront payment in February 2024, with the licensing amounts denominated in U.S. dollars. It received the $85 million option-exercise fee in May 2025 and said the latter would be recognized as revenue in 2025. Those two receipts total $155 million, calculated from the disclosed payments. Under the agreement, Abbisko is eligible for up to $605.5 million in payments including upfront, development and commercial milestones, plus double-digit percentage royalties on annual worldwide net sales.

Phase 3 Evidence Links Tumor Response to Function

The companies describe TGCT as a rare, locally aggressive tumor affecting joints, tendon sheaths and bursae. Its symptoms include pain, swelling, stiffness and reduced mobility; untreated or recurrent disease may cause irreversible damage to bone, joint and surrounding tissues. Overexpression of colony-stimulating factor 1 (CSF-1) in neoplastic synovial cells drives the disease by causing CSF-1R-expressing inflammatory cells to accumulate in the tumor.

The FDA decision rests on primary and longer-term results from MANEUVER, a global Phase 3 study in patients eligible for systemic therapy who had not received prior anti-CSF-1/CSF-1R therapy. In the double-blind first part, 94 patients were randomized 2:1 to receive 50 mg of PIMJETMI once daily (63 patients) or placebo (31 patients) for 24 weeks. Eligible patients could then move to open-label treatment and an extension phase.

EMD Serono reported that blinded independent review using RECIST v1.1 measured a week-25 objective response rate of 56% with PIMJETMI versus 3% with placebo (p<0.0001). The trial also produced statistically significant improvements in relative range of motion, physical functioning and pain. At a median 14.3-month follow-up among patients initially randomized to pimicotinib, median duration of response had not been reached, and 77% of patients who had responded at that assessment maintained clinical benefit after an additional 12 months. The functional measures add a patient-centered test of benefit beyond tumor shrinkage, addressing symptoms that limit daily activities.

EMD Serono reported no evidence of cholestatic hepatotoxicity or hair or skin hypopigmentation in MANEUVER. During the randomized double-blind phase, treatment-emergent adverse events led to discontinuation in 1.6% of pimicotinib-treated patients and dose reductions in 7.9%.

The FDA-approved prescribing information reproduced with the release warns that PIMJETMI can cause serious liver problems and that increased liver enzymes are common. It calls for liver blood tests before treatment and regularly thereafter.

A Fourth National Approval

The U.S. decision is PIMJETMI’s fourth marketing approval, following China in December 2025, Canada in June 2026 and Switzerland in October 2026. The U.S. application was reviewed under Project Orbis, an FDA Oncology Center of Excellence initiative for international regulatory collaboration, while reviews by other Project Orbis partners remained ongoing at the announcement.

The disclosed payments so far came from signing the license and expanding it worldwide. Sales-based milestones and royalties now tie additional income to Merck’s commercial uptake across approved markets, making the conversion of regulatory approvals into sales the next measurable stage of the agreement.