Case report: Neoadjuvant-intent pembrolizumab resulted in complete response in a xeroderma pigmentosum patient with locally advanced resectable cutaneous squamous cell carcinoma of the nose.

Background: Anti-PD1 antibodies have gained popularity in the treatment of skin cancers. These drugs have been FDA approved for treatment of cutaneous melanoma and unresectable/metastatic squamous cell carcinoma of the skin. However, the use of anti-PD1 antibodies is not established for resectable cutaneous squamous cell carcinoma, as the mainstay treatment is surgical excision.

Case: A 49-year-old female with Xeroderma Pigmentosum presented with an ulcerating lateral nasal mass causing obstruction. Biopsy confirmed cutaneous squamous cell carcinoma and was staged as IVA (T2N2cM0) based on PET-CT findings, which showed a 2.7 × 2.3 cm left nasal mass and radiotracer-avid cervical lymph nodes. Despite surgical recommendations, the patient declined surgery due the expected morbidity and disfigurement. Instead, she received neoadjuvant Pembrolizumab (200 mg IV every 3 weeks). After two cycles, PET-CT and MRI showed significant reduction in the nasal mass and decreased cervical lymph node involvement. On physical exam, the nasal lesion had resolved. Multidisciplinary tumor board discussion recommended radiation therapy instead of neck dissection, considering the patient's clinical response and potential surgical morbidity. After a third Pembrolizumab cycle, she received 66 Gy in 33 fractions, followed by continued adjuvant immunotherapy.