The United States Food and Drug Administration (USFDA) has approved Valchor (Mechlorethamine topical gel) for the treatment of stage IA and IB mycosis fungoides-type cutaneous T-cell lymphoma (CTL). The indication is specific for patients who are previously treated with skin-directed therapy. The agency has approved intravenous Valchor for treatment of mycosis-fungoides.
Prior to approval, pharmacy-compounded aqueous-based topical formulations or petroleum ointments were used to treat such medical conditions.
According to Dr. Stuart Lessin, President of Board of Directors, Cutaneous Lymphoma Foundation and PI of Valchor clinical trial, the efficacy of topical mechlorethamine was tested and documented over years. However, for the first time, the drug was tested rigorously for approval. The drug was designed in accordance with GCP guidelines, and the drug was tested with patient support and assistance programmes.
A randomized, single-blinded, non-inferiority pivotal study was conducted by the manufacturer for drug approval. The trial compared pharmacy-compounded mechlorethamine preparation with mechlorethamine in patients with stage IA, and IB mycosis-fungoides associated CTL.
All the participants were assigned to receive at least one skin-directed treatment such as topical nitrogen mustard, topical corticosteroid, bexarotene gel or phototherapy. Cases of refraction and/or intolerance to prior treatments were excluded from the study.
After 12 months of treatment, evidential therapeutic response was observed in about 60% of the mechlorethamine-treated patients. About 50% reduction in the Composite Assessment of Index Lesion Severity (CAILS) score was also documented in the same treatment group. However, 48% confirmed response was observed in the control group.
In the treatment group, initial CAILS response was observed after one month of treatment and complete response after 11 months of mechlorethamine treatment. No systemic absorption was reported in the treatment group.