Pembrolizumab and concurrent hypo-fractionated radiotherapy for advanced non-resectable cutaneous squamous cell carcinoma.

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is the second most frequent non-melanoma skin cancer. Treatment options for inoperable advanced cSCC cases are limited. The efficacy of anti-programmed cell death-1 (PD-1) monoclonal antibodies (mAb) has been reported recently in some patients with cSCC.

OBJECTIVES

To evaluate the efficacy of anti-PD-1 mAb in a case series of inoperable advanced cSCC and to analyse the efficacy of concurrent radiotherapy.

MATERIALS AND METHODS

We retrospectively analysed the files of all patients with advanced inoperable cSCC treated with anti-PD-1 mAb and concurrent radiotherapy outside clinical trials in our skin cancer centre before December 31, 2017.

RESULTS

A total of four patients with locally or regionally advanced cSCC were identified. All patients received pembrolizumab at 2 mg/kg every three weeks and concurrent radiotherapy. Two patients who received pembrolizumab as first-line therapy with concurrent radiotherapy (one with skull and leptomeningeal invasion and one with rapidly progressing regional cSCC) had a complete response, allowing treatment discontinuation, without recurrence after a median of 11 months off treatment. All other patients experienced progressive disease. The median progression-free survival and overall survival were 14.4 and 15.6 months, respectively. No toxicity was observed.

CONCLUSION

There appears to be a place for pembrolizumab as first-line treatment for unresectable or advanced cSCC. Further studies are needed to evaluate concomitant radiotherapy with anti-PD1 antibodies.