Outcome of localized therapy for residual or recurrent oligo melanoma or renal cell cancer (RCC) following immune checkpoint inhibition therapy (ICI).

Abstract

e14665 Background: Melanoma and RCC care has been revolutionized by ICI, rendering many patients long term disease progression free. ICI response outcome is mainly categorized as non-, partial- or complete-response, which is based on RECIST radiographic measurements of existing and new cancer sites, without considering whether these sites contain viable tumor that has metastatic potential. We hypothesized that ICI may lead to residual radiographic abnormalities that either contain non-viable tumor or tumor without metastatic potential that can be cured with local therapy. Methods: In this retrospective study, patients with either metastatic melanoma or RCC, treated with ICI and who underwent resection or SBRT of either residual or newly developed oligo-metastatic disease were identified from the MedStar-Georgetown EMR. Patient’s history, cancer treatment outcome, surgical pathology and subsequent disease status were collected. Results: We identified 8 patients with melanoma and 5 with RCC who had an operable oligo-metastasis after ICI response (5 females, 9 males, 39 – 87 age range). 62% received one ICI regimen. The last ICI regimen was nivolumab + ipilimumab followed by nivolumab maintenance in 8 (62%), nivolumab alone in 2 (15%) and a pembrolizumab-based combination in 3 (23%). The last regimen was given for median 15(2-24) and 17(9-26) months for melanoma and RCC, respectively. At initiation of that ICI regimen, 12 (92%) patients had stage IV and 1 (8%) had an unresectable stage III disease. The ICI was stopped in 8 (62%) cases because of major disease regression or completion of regimen, in 3 (23%) due to adverse event and in 2 (15%) due to disease progression. Within melanoma and RCC groups 46% had a lesion that persisted following ICI and 54% developed a new lesion after stopping ICI. Each patient had only one such lesion that localized to the hepatobiliary system, soft tissue, lymph node, small bowel, brain, skin or nephrectomy bed. After surgical removal or radiosurgery treatment of the lesion, all patients have no evidence of melanoma or RCC recurrence for a median of 3(1-9) or 1(1-5) year, respectively. Based on histological analysis, 5 (38%) of the resected samples showed no viable tumor. Conclusions: ICI therapy in melanoma and RCC may lead to a response where existing lesions or new lesions either have no viable cancer or lose their metastatic capacity. Surgical removal or SBRT treatment of these lesions can render such patients long term disease free. Consideration of local therapy approaches in patients with residual or recurrent oligo-metastatic disease is clinically justified.