Topical Dermaprazole for Radiation Dermatitis in Breast Cancer and Head and Neck Cancer Patients (TOPAZ)

For this study, patients will be stratified into one of the following two arms: 1) head and neck or 2) breast cancer. All study participants will begin using Dermaprazole for 1-2 weeks prior to receiving radiation. During the CT Simulation, study participants will be instructed to apply Dermaprazole in a "patch test" area - an area of the chest outside of the field of radiation. This is to assess for immediate skin reactions including itching, irritation and allergy. If there are no immediate allergic reactions at the conclusion of the simulation visit, the study participant will be instructed to apply the cream in the area that will be irradiated in addition to the patch test area for 1-2 weeks until the radiation starts. During this period, if the patient is found to have no adverse events, they will then continue daily application both in the patch test area and in the radiation field during radiotherapy, and for 2 weeks after they complete their radiation treatment. During the entire time while using the Dermaprazole, study participants will be evaluated for adverse events such as contact dermatitis in the patch test area as well as radiation dermatitis within the treatment field. All participants will be followed for 6 months after the final Dermaprazole application.

Two dose levels of Dermaprazole (1% and 2%) will be evaluated in the combination Phase I/II dose escalation/de-escalation BOIN design study evaluating preliminary efficacy at the Maximum Feasible Dose (MFD). The Dermaprazole will be initiated at a dose of 1% and escalated to 2% as appropriate based on the number of adverse events. A Dose Limiting Toxicity (DLT) will be defined as any of the following: a) any > Grade 2 skin toxicity outside the radiation field (Macules/ papules covering 10-30% of the area with or without symptoms of pruritus, burning, tightness), b) any > Grade 2 radiation dermatitis (Moderate to brisk erythema; patchy moist desquamation, mostly confined to skin folds and creases; moderate edema) inside the radiation field that is probably or definitely related to Dermaprazole (AE attribution will be at the discretion of the study PI/Co-I). c) Any > Grade 4 radiation dermatitis inside the radiation field. A DLT will be detected from the first day the subject starts applying the Dermaprazole cream until 1 month after the subject has completed their last radiation treatment. Dermatitis will be evaluated by a radiation oncologist on a weekly basis using the Common Terminology Criteria for Adverse Events (CTCAE) V5.0 criteria, and all radiation dermatitis scores will be independently verified by a dermatologist who will evaluate the photographs at the end of treatment. Patient reported quality of life will be evaluated using a validated survey instrument called SkinDex16.