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FDA grants pexidartinib breakthrough therapy designation for tenosynovial giant cell tumor
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The FDA has granted breakthrough therapy designation to the oral CSF-1R inhibitor pexidartinib for the treatment of tenosynovial giant cell tumor that cannot be surgically removed due to the risks for worsening functional limitation or severe morbidity, according to a press release from the drug’s manufacturer.
Primary treatment of tenosynovial giant cell tumor (TGCT) — a group of neoplasms that includes pigmented villonodular synovitis and giant cell tumor of the tendon sheath — includes surgery. However, surgery may be more difficult or impossible for patients with a diffuse form of the disease, where the tumor can wrap around bone, tendons, ligaments and other parts of the joint.
“Surgery is the primary treatment for TGCT, but for patients with a diffuse form of the condition, the tumor is more difficult to remove and has a high rate of recurrence, resulting in multiple complicated surgeries and even amputation in some patients,” Mahmoud Ghazzi, MD, PhD, executive vice president and global head of development for Daiichi Sankyo, said in a press release. “We are pleased that the FDA recognizes the unmet need for the treatment of TGCT and we look forward to working closely with the Agency on the expedited development of this potential non-surgical treatment for patients with TGCT.”
The FDA based its decision in part on results of a phase 1 study — published in July in The New England Journal of Medicine — that evaluated the safety and efficacy of pexidartinib (PLX3397; Plexxikon, Daiichi Sankyo). The most common treatment-related adverse events observed in this study included fatigue, hair color changes, nausea, dysgeusia and periorbital edema.
ENLIVEN — a phase 3 trial evaluating pexidartinib — is currently enrolling patients with symptomatic TGCT for whom surgery may not be an option. Pexidartinib is also under investigation for the treatment of glioblastoma, melanoma, ovarian and breast cancer, as well as in combination with pembrolizumab (Keytruda, Merck) for advanced melanoma and other multiple solid tumors.
“The responses seen in our ongoing phase 1 study provided initial proof-of-concept that selective CSF-1R inhibition with pexidartinib may safely and effectively reduce tumor burden in patients with TGCT, providing the rationale to move directly into a phase 3 clinical trial,” Gideon Bollag, PhD, CEO of Plexxikon, said in a press release. “This breakthrough therapy designation represents another significant milestone in our commitment to develop novel targeted agents that address unmet medical needs in rare conditions such as TGCT.”