Study of Prophylactic Topical Dapsone 5% Gel Versus Moisturizer for Cetuximab-induced Papulopustular (Acneiform) Rash in Patients With mCRC or HNSCC Without Previous or Concurrent RT

Exclusion Criteria

• •Females of childbearing potential who are pregnant or nursing
• •Patients with allergy, hypersensitivity or other contraindication to dapsone, sulfa antibiotics, or excipients of the dapsone gel product
• •Patients with pre-existing dermatologic condition affecting the face and chest that would impair assessment of papulopustular rash including dense and/or long facial hair (per investigator discretion)
• •Patients currently using prescription and/or over-the-counter topical medications to the face and/or chest who are unwilling to discontinue use during the trial intervention period (day 0 ± 2 days through day 28 ± 2 days)
• •Previous or concurrent radiation therapy to head, neck, and chest (i.e. application sites only)
• •Previous therapy with cetuximab within 6 months of consent