The FDA has granted marketing approval for Ceptaris Therapeutics, Inc.'s orphan drug Valchlor (mechlorethamine) gel for the topical treatment of stage IA and IB mycosis fungoides-type cutaneous T-cell lymphoma (CTCL) in patients who have received prior skin-directed therapy. Valchlor, the first FDA-approved topical formulation of mechlorethamine, commonly known as nitrogen mustard, is a gel that is applied topically once a day and dries on the skin.

Mechlorethamine is a chemotherapeutic agent previously approved for intravenous treatment of mycosis fungoides. The National Comprehensive Cancer Network (NCCN) currently recommends topical mechlorethamine preparations for the treatment of early stage CTCL. According to Ceptaris, prior to the approval of Valchlor, there were no FDA-approved topical mechlorethamine products; only non-standardized, pharmacy-compounded petroleum ointment or aqueous-based topical preparations were available.

The approval of Valchlor was based on a randomized, observer-blinded, non-inferiority pivotal trial comparing Valchlor to a pharmacy-compounded mechlorethamine preparation in patients with stage IA-IIA MF-type CTCL. Patients had received at least one prior skin-directed therapy. Qualifying prior therapies included topical corticosteroids, phototherapy, Targretin gel, and topical nitrogen mustard (mechlorethamine). Patients were not required to be refractory to or intolerant of prior therapies. In the 13-center study, 260 patients (the vast majority of whom were IA and IB) were enrolled (1:1 randomization), making it the largest randomized study ever conducted in mycosis fungoides-type CTCL. Results of the study, which were published earlier this year in JAMA Dermatology, showed that 60% of patients treated with Valchlor had a confirmed response at 12 months, defined as reduction of at least 50 percent in the Composite Assessment of Index Lesion Severity (CAILS) score, while 48 percent of those treated with the compounded control achieved a confirmed response. Complete responses constituted a minority of the CAILS overall response. CAILS responses were seen as early as one month, with further responses observed through 11 months of treatment. No systemic absorption of mechlorethamine was detected with Valchlor treatment.