The FDA granted marketing approval to an orphan drug for the topical treatment of stage 1A and 1B mycosis fungoides-type cutaneous T-cell lymphoma (CTCL).

Mechlorethamine gel (Valchlor) is for use in persons who have received prior skin-directed therapy. This chemotherapeutic agent, also referred to as nitrogen mustard, was previously approved for the intravenous treatment of mycosis fungoides, the most common type of CTCL.

As noted by manufacturer Ceptaris Therapeutics, Inc. (Malvern, Pennsylvania), Valchlor is the first FDA-approved topical preparation of mechlorethamine. Previously, only nonstandardized, pharmacy-compounded petroleum ointment or aqueous-based topical preparations had been available.

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In the observer-blinded, noninferiority pivotal trial that led to the FDA approval, 260 persons with stage 1A-2A (mostly stage 1A or 1B) mycosis fungoides-type CTCL were randomized to treatment with Valchlor or with a pharmacy-compounded mechlorethamine preparation. All patients had undergone at least one prior skin-directed therapy with topical corticosteroids, phototherapy, bexarotene (Targretin) gel, and/or topical nitrogen mustard. Participants were not required to be refractory to or intolerant of prior therapies.

The majority of patients (60%) undergoing treatment with Valchlor had a confirmed response at 12 months (reduction of at least 50% in the Composite Assessment of Index Lesion Severity, or CAILS, score), compared with 48% of participants receiving the compounded control treatment. CAILS responses were seen as early as 1 month of therapy, with further responses observed through 11 months of therapy. No systemic absorption of mechlorethamine was detected with Valchlor treatment.