7 June 2023, Shanghai – Abbisko Therapeutics Co., Ltd. (“Abbisko Therapeutics” hereafter) today announced that its novel CSF-1R inhibitor Pimicotinib (ABSK021）has been granted the Priority Medicine (PRIME) designation by the European Medicines Agency (EMA) for the treatment of tenosynovial giant cell tumor (TGCT) patients that are not amenable to surgery. The PRIME designation was granted based on clinical results from the ongoing phase Ib clinical trial of TGCT cohort for Pimicotinib. PRIME is similar to breakthrough therapy designation (BTD) in the other countries with the goal to expedite the development and review of new medicines indicated for serious or life-threatening conditions.

Pimicotinib is a novel and potential best-in-class CSF-1R inhibitor. Previously, Pimicotinib was granted BTD by the Center for Drug Evaluation, NMPA, in July 2022, and by the U.S. Food and Drug Administration in January 2023. With the PRIME designation by EMA, it demonstrates that the clinical data of Pimicotinib has been well recognized by regulatory agencies globally with support to accelerate its clinical development and advancement into commercialization.

The eligibility criteria for PRIME are identical to EMA’s accelerated assessment criteria. It is scheme to reinforce scientific and regulatory support to enable accelerated development and assessment of new medicines. It targets medicines to solve major unmet medical needs and with therapeutic innovations. PRIME mainly needs to meet two requirements: Firstly, target conditions with an unmet medical need, i.e. for which there exists no satisfactory method of diagnosis, prevention or treatment in the Community or, even if such a method exists, in relation to which the medicinal product concerned will be of major therapeutic advantage to those affected; Secondly, demonstrate the potential to address the unmet medical need for maintaining and improving the health of the Community, for example, by introducing new methods of therapy or improving existing ones.

About Pimicotinib

Pimicotinib is a novel, orally available, highly selective, and highly potent small molecule inhibitor of CSF-1R independently discovered and developed by Abbisko Therapeutics. A number of studies have shown that blocking the CSF-1R signaling pathway could effectively modulate and change macrophage functions, and potentially treat many macrophage-dependent human diseases. Prior to these, Pimicotinib demonstrated significant antitumor efficacy in a phase Ib trial in patients with TGCT, achieving ORR of 77.4% and favorable safety profile, which presented in the 2023 ASCO. Abbisko has advanced Pimicotinib into a global phase III MRCT trial for TGCT, and completed dosing of the first patient in April, 2023.

Abbisko Therapeutics has completed a Phase Ia dose escalation study for ABSK021 in the U.S. and is conducting an ongoing Phase Ib multi-cohort expansion trial in both the U.S. and China. In addition to TGCT and cGVHD that have been approved by NMPA for a phase II clinical studies, Abbisko Therapeutics is actively exploring the potential of ABSK021 in treating many other types of solid tumors and non-oncology indications including amyotrophic lateral sclerosis (ALS). As of today, no highly selective CSF-1R inhibitor has been approved in China.

About TGCT

TGCT, also known as pigmented villonodular synovitis, is a locally aggressive neoplasm which affects synovial joints, mucous sacs, and tendon membranes, resulting in swelling, pain, stiffness, and decreased activity of the affected joints which seriously affect the patient's quality of life. According to the 2013 World Health Organization classification, TGCTs were classified as localized TGCT and diffuse TGCT. Compared with localized TGCT (80%-90%), the incidence rate of diffuse TGCT is lower (10-20%). Overexpression of colony-stimulating factor 1(CSF1) occurs in most TGCTs.

Surgical resection is the standard treatment for TGCT. However, not all patients are suitable for surgical treatment. It is difficult to remove tumors of diffuse patients by surgery, which may possibly lead to severe joint damage, total synovectomy, joint replacement, or even amputation, and the risk of surgical complications can be high. It has been reported that more than 50% of patients with diffuse TGCT will undergo recurrence after surgical resection. For those TGCT patients not amenable to surgery, there is currently no approved drug available in China.