Radiotherapy and EGFR inhibition for high-risk cutaneous squamous cell carcinoma in immunosuppressed patients.

e21562 Background: Immunosuppression (IS) is a recognized risk factor for cutaneous squamous cell cancer (cSCC) incidence, recurrence and disease-specific death, though there are limited data on treatment outcomes in this population. Prior studies in unselected patients with high risk (HR) cSCC, failed to show improved outcomes from the addition of carboplatin to post-operative radiotherapy (PORT), however benefits may be better appreciated in higher risk groups. The addition of epidermal growth factor receptor inhibitors (EGFRi) to PORT has shown improved outcomes in HR-cSCC over historical controls in the general population, but its impact on patients with comorbid IS is unknown. Methods: This single institution retrospective cohort study identified all patients with a history of a solid organ transplant or autoimmune disease requiring IS or with hematologic malignancy and a diagnosis of either primary or recurrent HR-cSCC treated with concurrent EGFRi + PORT. Patients who failed to receive either modality concurrently or lost to follow-up after completion of therapy were excluded. Event-free survival (EFS) was defined as time from initiation of RT to disease recurrence, progression, or death from any cause. Results: Of 24 identified patients, 18 received concurrent EGFR inhibitor therapy and radiotherapy (mean dose 59.4 Gy delivered in 29.7 fractions) and had adequate follow-up for analysis. Fifteen patients were solid organ transplant recipients receiving immunosuppression, two had hematologic malignancies, and one had an autoimmune condition requiring chronic immunosuppression. Most patients had advanced disease, with 72.2% classified as AJCC stage III–IV and 88.9% as BWH stage T2b–T3 (T2b 50.00%; T3 38.9%). 8 of 18 (44.4%) had nodal disease involvement and 6 of 18 (33.3%) had satellite or in-transit metastases, and 2 of 18 (11.1%) had both. Median event-free survival was 5.4 months. Average follow up time was 18 months. Conclusions: IS represents a potent risk factor for cSCC recurrence or death, and outcomes remain poor even with intensification of PORT with concurrent EGFRi +RT. Such patients may benefit from a more intensified chemoRT regimen and/or the addition PD-1 inhibition in the adjuvant setting where tolerated.