An Open Label Phase II Trial of Topical Sirolimus for the Treatment of Refractory Oral Chronic Graft-versus-Host-Disease

Inclusion Criteria: * While there will be no restrictions on concurrent systemic medications, all subjects must be on a stable immunomodulatory medication regimen for 7 days prior to beginning the study without plans to adjust doses during the following four-week study period. Dose modifications to maintain therapeutic drug levels of immunosuppressants (i.e. tacrolimus and sirolimus) during the study intervention period are allowed and do not constitute a trial violation. Changes in medications for non-cGVHD medical conditions will not affect eligibility. * Age 4 years and older. * Patients with symptomatic oral chronic graft-versus-host disease (sensitivity score ≥ 4). * Stable topical steroid therapy with dexamethasone, clobetasol, or budesonide oral solutions (5 min, four times a day) for seven days prior to study enrollment. * Stable systemic cGVHD medication regimen for seven days prior to study enrollment. Dose modifications to maintain therapeutic drug levels of immunosuppressants (i.e. tacrolimus and sirolimus) for the month prior and during the study intervention period are allowed and do not constitute a trial violation. * The effects of sirolimus on the developing human fetus are unknown. For this reason and because immunosuppressants agents as well as other therapeutic agents used in this trial are known to be teratogenic, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. Men treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of study participation, and 4 months after completion of topical sirolimus administration. * Ability to understand and the willingness to sign a written informed consent document. Exclusion Criteria: * Patients already using topical sirolimus therapy. * Patients who have an allergy/intolerance to sirolimus. * Sensitivity score ≤ 3. * Inability to comply with study instructions. * Pregnant or breastfeeding. * Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. * Pregnant women are excluded due to the potential for teratogenic or abortifacient effects. Because there is an unknown but potential risk for adverse events in nursing infants, breastfeeding should be discontinued if the mother is treated with sirolimus. * HIV-positive participants on combination antiretroviral therapy are ineligible because of the potential for pharmacokinetic interactions with sirolimus. In addition, these participants are at increased risk of lethal infections when treated with marrow-suppressive therapy. Appropriate studies will be undertaken in participants receiving combination antiretroviral therapy when indicated.