Pimicotinib Significantly Improved Outcomes for Patients with Tenosynovial Giant Cell Tumor in a Global Phase III Trial

– The MANEUVER study met the primary endpoint with an objective response rate (ORR) at week 25 of 54.0% compared with 3.2%  for placebo (p< 0.0001 ) –
– Statistically significant and clinically meaningful improvements also seen in all key secondary endpoints, including pain and stiffness -
– Treatment with oral, once-daily pimicotinib was well-tolerated, with very low rates of discontinuation due to treatment-related adverse events –
–  Updated results from Phase 1b study of pimicotinib demonstrated best ORR of 85% with median treatment duration of 20 months –

SHANGHAI, Nov. 11, 2024 /PRNewswire/ -- Abbisko today announced that the Phase 3 MANEUVER study evaluating pimicotinib in the treatment of tenosynovial giant cell tumor (TGCT) achieved statistically significant improvements in objective response rate (ORR) at Week 25 of 54.0%, compared with 3.2% for placebo (p< 0.0001) based on RECIST v1.1 per Blinded Independent Review Committee（BIRC）. 

Notably, the study also showed that treatment with pimicotinib provided statistically significant and clinically meaningful improvements in secondary endpoints associated with important patient outcomes in TGCT, including stiffness by Numeric Rating Scale (NRS; -3.00 mean change from baseline vs. -0.57  for placebo, p<0.0001) and pain by Brief Pain Inventory (BPI; -2.32 vs. 0.23 mean change from baseline, p<0.0001). Further efficacy and safety data from Part 1 of the MANEUEVER study will be presented at an upcoming medical conference.

In MANEUVER, pimicotinib was well-tolerated, and the safety profile was consistent with prior reported data, with no evidence of cholestatic hepatotoxicity. Treatment-emergent adverse events (TEAEs) leading to treatment discontinuation occurred in 1.6% (n=1) of patients treated with pimicotinib; TEAEs leading to dose reduction occurred in 7.9% (n=5) of pimicotinib-treated patients.

"TGCT tends to be a disease of the young. This rare, benign tumor that grows in and around the joints primarily affects young and middle-aged adults in their working years. The swelling, pain, stiffness and limited mobility caused by the disease can have a significant impact on the ability to perform daily activities, limiting patients' work and social lives. Treatment often involves surgery, yet the high recurrence rate and potential complications from repeated surgical interventions can be very challenging for patients to deal with, creating an urgent need for systemic therapy that could control tumor growth," said Professor Niu Xiaohui, Director of the Bone and Soft Tissue Tumour Diagnosis and Research Centre at Beijing Jishuitan Hospital. "Based on these new data from the MANEUVER study, together with once-daily oral administration that may promote long-term adherence and pimicotinib's  selective inhibition of CSF-1R, this investigational medicine has the potential to establish a new treatment paradigm for patients with TGCT. "

Yaochang Xu, Chairman and CEO of Abbisko Therapeutics, said, "As the first global trial to enroll both Asian and Western patients with TGCT in balanced proportions across multiple regions, MANEUVER is a landmark global study that allows for detailed outcome comparisons. This can facilitate a deeper understanding of disease characteristics and potential similar response across different populations. This unique study shows that pimicotinib has the potential to provide a novel oral small molecule therapy option for TGCT patients, representing a key advancement within the emerging class of CSF-1R inhibitors. We look forward to collaborating with Merck as we pursue registration of pimicotinib as the first therapy option indicated for the systemic treatment of TGCT in China."

In December 2023, Abbisko Therapeutics entered into a licensing agreement granting Merck, a leading science and technology company headquartered in Darmstadt, Germany, an exclusive license to commercialize pimicotinib in Chinese mainland, Hong Kong, Macau, and Taiwan, as well as an exclusive option for global commercial rights of pimicotinib.

"There is a tremendous unmet need for effective, well-tolerated systemic treatment for TGCT, a disease primarily caused by CSF-1 overexpression that leads to joint tissue thickening and overgrowth, severely impacting patients' lives. These Phase III data from MANEUVER confirm results of Abbisko's Phase I study, indicating that targeting CSF-1R with pimicotinib has the potential to offer a new treatment option for patients. As we work with Abbisko to review the data from this study and prepare to share it with regulators in China, we are focused on our shared goal of bringing pimicotinib to patients in need," said Danny Bar-Zohar, Global Head of Research & Development and Chief Medical Officer for the Healthcare business sector of Merck.

About MANEUVER

The pivotal Phase 3 MANEUVER study is a three-part, randomized, double-blind, placebo-controlled study to assess the efficacy and safety of pimicotinib in patients with TGCT who are eligible for systemic therapy and who have not received prior anti-CSF1/CSF1R therapy. The study is being conducted in China (n=45), Europe (n=28), and the US and Canada (n=21).

In the double-blind Part 1, 94 patients were randomized 2:1 to receive either 50 mg QD of pimicotinib (n=63) or placebo (n=31) for 24 weeks. The primary endpoint is objective response rate (ORR) at Week 25 as measured by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 by BIRC in the intent-to-treat (ITT) population. Secondary endpoints include tumor volume score, active range of motion, stiffness by Numeric Rating Scale (NRS), pain by Brief Pain Inventory (BPI), and physical function measured by PROMIS.

After the double-blind Part 1, eligible patients may continue to the open-label Part 2 for up to 24 weeks of dosing. Patients who complete Part 2 may then enter the open-label extension phase (Part 3) for extended treatment and safety follow-up.

Updated long-term follow-up results from the phase 1b study of pimicotinib in TGCT

Abbisko also announced the updated results from the Phase 1 open-label, multicenter study evaluating the safety and efficacy of pimicotinib in patients with TGCT. The poster, titled, "Long-term efficacy and safety profile of Pimicotinib (ABSK021) in tenosynovial giant cell tumor: Phase 1b update," will be presented at the Connective Tissue Oncology Society 2024 Annual Meeting in San Diego, United States on November 13-16, 2024.

As of June 30, 2024, data from 42 patients who received the 50 mg dose of pimicotinib showed:

- The best ORR was 85.0% by RECIST v1.1 per IRC. With a median treatment duration of 20.67 months (0.5, 30.1), 54.8% and 38.1% patients had an exposure of ≥ 18 months and ≥ 24 months, respectively. The median duration of response was not reached (NR) by Kaplan-Meier estimates, and 69.0% patients remained on treatment. Continuous and gradual improvement in tumor regression, pain and stiffness relief, and joint mobility were observed during long-term treatment.
- The overall safety profile remains largely consistent, with no distinct adverse events emerging upon long-term follow-up.
- No evidence of cholestatic hepatotoxicity was observed.

SOURCE Abbisko