Tumor Treatment Pexidartinib Nabs Breakthrough Therapy Designation

The FDA has given breakthrough therapy designation to Daiichi Sankyo and Plexxikon Inc’s investigational oral CSF-1R inhibitor pexidartinib to treat tenosynovial giant cell tumor (TGCT).

Pexidartinib (formerly called PLX3397) would be used to treat TGCT when surgical removal of the tumor is linked with potentially worsening functional limitation or severe morbidity.

There is currently no FDA-approved treatment for treating this rare tumor involving the joint or tendon sheath.

The breakthrough therapy designation was given based on the results of a phase 1 study that provided evidence that pexidartinib could safely and effectively reduce tumor burden.

Now, a phase 3 study is currently enrolling patients with symptomatic tenosynovial giant cell tumor.

"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," said Mahmoud Ghazzi, executive vice president and global head of development for Daiichi Sankyo, 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."

Adverse effects associated with pexidartinib in the phase 1 trial included fatigue, nausea, hair color changes, and diarrhea.