Merck advances pimicotinib in China as Center for Drug Evaluation accepts TGCT marketing application following pivotal Phase 3 data

German science and technology conglomerate Merck announced a key regulatory milestone this week, confirming that the China National Medical Products Administration (NMPA)’s Center for Drug Evaluation (CDE) has formally accepted its marketing application for pimicotinib, a colony stimulating factor-1 receptor (CSF-1R) inhibitor developed for tenosynovial giant cell tumor (TGCT). This follows the May 2025 Priority Review designation granted by the CDE and is supported by strong data from the global Phase 3 MANEUVER study.

Merck aims to position pimicotinib—originally developed by Shanghai-based Abbisko Therapeutics—as a first-in-class systemic treatment for TGCT in China, which, if approved, could mark the first systemic therapy available for the disease in the region. The drug is currently undergoing regulatory preparations for global submissions, including an upcoming New Drug Application to the U.S. Food and Drug Administration.

TGCT is a rare and often recurring joint tumor with limited systemic options. The approval pathway for pimicotinib—now bolstered by Phase 3 data and regulatory designations in China, the U.S., and the European Union—represents an inflection point in addressing this unmet medical need.

What is tenosynovial giant cell tumor and why does it need systemic therapy?

TGCT is a non-malignant but locally aggressive tumor that arises in the joint, tendon sheath, or bursa. Though benign in histology, its biological behavior includes progressive joint destruction, chronic inflammation, pain, stiffness, and loss of mobility, primarily in a working-age demographic. While surgical resection remains a frontline option, recurrence is common, and repeat interventions carry increased morbidity.

The condition’s pathophysiology is driven by overexpression of CSF-1, which attracts macrophages that contribute to tumor volume and joint inflammation. Pimicotinib, as a potent CSF-1R inhibitor, directly targets this disease mechanism, offering the potential for tumor volume reduction and symptom relief in patients with diffuse or unresectable TGCT.

With no approved systemic therapies currently available in China and only limited options elsewhere, pimicotinib’s clinical profile and Priority Review status reflect the urgency for novel medical interventions in this therapeutic space.

What does the Phase 3 MANEUVER study reveal about pimicotinib?

The marketing submission to the CDE is anchored in clinical evidence from Part 1 of the global Phase 3 MANEUVER study, which evaluated pimicotinib’s efficacy and safety in patients with advanced or inoperable TGCT. Patients were randomized 2:1 to receive pimicotinib 50 mg once daily or placebo over a 24-week double-blind period.

According to Merck, the trial met its primary endpoint, with the pimicotinib group achieving an objective response rate (ORR) of 54.0%, compared to just 3.2% in the placebo arm at week 25, based on assessments by a blinded independent review committee (BIRC) using RECIST v1.1 criteria. The statistical significance (p<0.0001) underscores the drug’s clinical robustness.

Secondary outcomes also favored pimicotinib, with meaningful improvements in pain, stiffness, range of motion, and physical function, measured via validated patient-reported instruments such as the Numeric Rating Scale (NRS) and Patient-Reported Outcomes Measurement Information System (PROMIS). These data were presented at the 2025 ASCO Annual Meeting, enhancing visibility among the oncology community.

The three-part trial, run by Abbisko Therapeutics, enrolled patients across China (n=45), Europe (n=28), and North America (n=21). The open-label Part 2, currently underway, allows eligible patients to continue pimicotinib treatment for an additional 24 weeks, with final results expected by mid-2025. Patients completing Part 2 may then enter Part 3, a long-term extension phase for continued treatment and safety follow-up.

Abbisko and Merck’s partnership positions pimicotinib for global commercialization

Pimicotinib, also known as ABSK021, is a highly selective oral small molecule developed by Abbisko Therapeutics. The oncology-focused Chinese drug developer has received regulatory support across multiple regions for the compound, including Breakthrough Therapy Designation from both the NMPA and U.S. FDA, and PRIME status from the European Medicines Agency (EMA)—a marker of promising clinical innovation.

Under the terms of their agreement, Merck holds exclusive global commercialization rights for pimicotinib outside of Abbisko’s core development territory. Merck’s decision to file the Chinese application through its own channels and pursue U.S. and global filings signals strategic confidence in the drug’s first-in-class potential and commercial viability.

“This acceptance and initiation of the priority review aligns with our goal to deliver the first systemic TGCT therapy in China,” said Hong Chow, Head of China and International Healthcare at Merck. “We believe pimicotinib’s profile—targeting not just tumor shrinkage but also functional outcomes like mobility and pain—can shift the treatment landscape for patients.”

What are institutional and investor signals telling us?

Though Merck is not listed on major U.S. exchanges, institutional observers have consistently tracked its innovation-driven strategy, especially within oncology. The company reported €21.2 billion in global revenues in 2024, supported by strong performance across its life science, healthcare, and electronics divisions.

Analysts have pointed to Merck’s recent clinical and regulatory wins in oncology as a core element of its international growth, particularly in Asia-Pacific markets. The pimicotinib filing aligns with Merck’s growing emphasis on targeted cancer therapies, complementing existing assets in immuno-oncology and rare diseases.

At the same time, Abbisko’s rising clinical presence, supported by cross-border development partnerships, places it among a new wave of Chinese biotechs with global R&D ambitions. The pimicotinib milestone reinforces Abbisko’s credibility as a CSF-1R development leader and may influence future fundraising or partnering opportunities, especially as open-label data becomes available later in 2025.

What’s next for pimicotinib and systemic TGCT therapies?

With China’s CDE already granting Priority Review, pimicotinib could receive a regulatory decision in an accelerated timeframe, potentially within six to nine months. If approved, it would mark a first-in-class systemic therapy in a disease space with virtually no prior treatment options beyond surgery.

Merck is preparing for parallel submissions in the United States and additional global markets, where regulatory pathways may similarly benefit from breakthrough or accelerated review designations. The availability of updated Phase 3 data from Part 2 of the MANEUVER trial will likely play a pivotal role in supporting these filings and informing broader clinical adoption.

Looking forward, experts anticipate pimicotinib may set a benchmark for new TGCT therapies, and its systemic efficacy could open discussions around earlier intervention or combination approaches, especially in patients who are not surgical candidates.

With global regulators increasingly focused on rare tumor indications and functional patient outcomes, pimicotinib’s trajectory could signal the emergence of a new therapeutic category within orthopedic oncology.