The objective of this clinical study is to compare the safety and effectiveness of Valchlor versus HyBryte following 12 weeks of treatment.

Participants will be randomized to receive HyBryte or Valchlor in a 1:1 randomization. Participants will be treated for 12 weeks and follow-up visits will be conducted 1, 2, and 4 weeks after completion of the treatment phase of the trial.

Prior to randomization, each participant will have at least 3 and up to 5 lesions identified (index lesions) that will be evaluated during the treatment phase and during the follow-up visits.

Inclusion Criteria:

• Minimum of 3 active treatment-accessible CTCL lesions
• Subjects must have a clinical diagnosis of cutaneous T-cell lymphoma (CTCL, mycosis fungoides), Stage IA, IB, or Stage IIA
• Subjects willing to follow the clinical protocol and voluntarily give their written informed consent
• Female subjects not pregnant nor nursing and willing to undergo a pregnancy test within 30 days prior to treatment initiation

Exclusion Criteria:

• History of severe allergic reaction to any of the components of HyBryte or mechlorethamine (Valchlor)
• Pregnancy or mothers who are breast-feeding
• All women of childbearing potential (WOCBP) and males with female partners who are WOCBP not willing to use effective contraception
• Subjects with history of sun hypersensitivity or photosensitive dermatoses (eg, porphyria, systemic lupus erythematosus (SLE), Sjogren's syndrome, etc.)
• Subjects whose condition is spontaneously improving
• Subjects receiving Valchlor (or any topical compound containing Mechlorethamine) in the preceding 2 months
• Subjects receiving topical steroids or other topical treatments (eg, targretin gel) on treatment accessible lesions for CTCL within 2 weeks of enrollment
• Subjects receiving systemic steroids, psoralen ultraviolet A (UVA) radiation therapy (PUVA), narrow band ultraviolet B (UVB) light therapy (NB-UVB) or carmustine (BCNU) or other systemic therapies for CTCL within 3 weeks of enrollment
• Subjects who have received electron beam irradiation within 3 months of enrollment
• Subjects with a history of significant systemic immunosuppression
• Subjects taking other investigational drugs or drugs of abuse within 30 days of enrollment
• Subject has any condition that, in the judgment of the Investigator, is likely to interfere with participation in the study
• Subjects receiving drugs known to cause photosensitization within 2 weeks of starting HyBryte therapy unless they have not had evidence of photosensitization after receiving a stable dose of the medication for a minimum of 4 weeks

From enrollment until end of follow-up, up to 16 weeks