History
The approval of pexidartinib was based on the results of a multi-center international clinical trial of 120 subjects, 59 of whom received placebo. The primary efficacy endpoint was the overall response rate (ORR) analyzed after 25 weeks of treatment. The clinical trial demonstrated a statistically significant improvement in ORR in subjects who received pexidartinib, with an ORR of 38%, compared to no responses in subjects who received placebo. The complete response rate was 15% and the partial response rate was 23%. A total of 22 out of 23 responders who had been followed for a minimum of six months following the initial response maintained their response for six or more months, and a total of 13 out of 13 responders who had been followed for a minimum of 12 months following the initial response maintained their response for 12 or more months.The U.S. Food and Drug Administration (FDA) granted the application for pexidartinib breakthrough therapy designation, orphan drug designation, and priority review designation. The FDA granted the approval of Turalio to Daiichi Sankyo. References
Further reading
"Pexidartinib". LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Bethesda, MD: National Institute of Diabetes and Digestive and Kidney Diseases. October 2019. PMID 31869194. NBK551730. Lamb YN (November 2019). "Pexidartinib: First Approval". Drugs. 79 (16): 1805–1812. doi:10.1007/s40265-019-01210-0. PMC 7044138. PMID 31602563. Roskoski R (February 2020). "Properties of FDA-approved small molecule protein kinase inhibitors: A 2020 update". Pharmacol. Res. 152: 104609. doi:10.1016/j.phrs.2019.104609. PMID 31862477. S2CID 209435035. External links
"Pexidartinib". Drug Information Portal. U.S. National Library of Medicine.
In patients receiving chemotherapy, it has been postulated that a high concentration of the cytotoxic drug in sweat has a direct toxic effect on the eccrine glands. Diagnosis
In all cases of suspected NEH, a skin biopsy should be performed, because the clinical symptoms are non specific, but the histopathological findings on the biopsy are specific. The biopsy shows characteristic changes of the eccrine glands, the major sweat glands of the body.In NEH, eccrine gland necrosis, and neutrophils surroundings the eccrine glands, are typical findings on biopsy. If the chemotherapy has recently been administered, chemotherapy induced neutropenia may be present, and, as a result, the neutrophils may be absent. But the other characteristic finding, i.e. eccrine gland necrosis, can still be seen. A vacuolar interface dermatitis also is visible in glands and ducts, along with necrosis of the lining cells. In addition, in patients receiving chemotherapy, keratinocyte atypia can be seen. Prevention
A single case report suggested that oral dapsone may be useful for prevention. However, the efficacy of oral dapsone as prevention has not been demonstrated very clearly until now. Treatment
NEH is self-limited and usually resolves without treatment. In the overwhelming majority of the cases, spontaneous resolution occurs within 1–2 weeks.