Complete lymph node dissection is the recommended treatment for clinically detectable lymph nodes in stage III melanoma. This surgery is associated with substantial morbidity. We hypothesize that combining percutaneous imaging-guided cryoablation of locoregional lymph nodes metastases with neoadjuvant in situ and systemic immunotherapy could allow disease control and evaluate the feasibility of this combination in this proof-of-concept study.

We enrolled 15 patients with stage IIIB/IIIC melanoma. Patients were treated as follows: a single 240 mg flat dose infusion of nivolumab on day 1, cryoablation under local anesthesia using CT on day 2, and a single intralesional injection of 10–20 mg of ipilimumab into the lymphadenopathy treated by cryotherapy on day 3. Five–eight weeks after this procedure, complete lymph node dissection was performed according to routine care. The primary outcome measure of this study was feasibility, measured as the number of failures (i.e., inability to complete the entire procedure).

The procedure was carried out successfully in 15 out of 15 patients with an observed number of failures of 0. The Bayesian analysis showed an estimated failure rate of 4.2% [0.2–20.6]. Eight patients (53%) had adverse events secondary to either immunotherapy or cryotherapy. Grade 3/4 events occurred in three patients, but all resolved quickly and patients could proceed to surgery as scheduled. Eight patients (53%) had a pathological complete or near complete response.

Combining percutaneous cryotherapy with in situ ipilimumab and systemic nivolumab for stage III resectable melanoma is feasible with tolerable toxicity.