Adjuvant immunotherapy of melanoma and development of new approaches using the neoadjuvant approach.

Melanoma is the third most common skin cancer but the leading cause of death from cutaneous malignancies. Although early-stage disease is frequently cured by surgical resection with excellent long-term survival, patients with deeper primary lesions (AJCC stage IIB-C) and those with microscopic (IIIA) or clinically evident regional lymph node or in-transit metastases (IIIB-C) have an increased risk of relapse and death, the latter approaching 70% or more at 5 years. In patients at high risk of recurrence/metastases, adjuvant therapy with high-dose interferon alpha-2b (HDI) following definitive surgical resection has been shown to improve relapse-free and overall survival. Neoadjuvant chemotherapy and/or radiotherapy have offered the prospect to improve regional recurrence risk and overall survival in several solid tumors. The advent of effective new molecularly targeted therapies for metastatic disease and new immunotherapies that overcome checkpoints of immune response have augmented the range of new options that are in current trial evaluation to determine their role as potential adjuvant therapies, alone and in combination with one another, and the established modality of IFN-α. The differential characteristics of the host immune response between early and advanced melanoma provide a strong mechanistic rationale for the use of neoadjuvant immunotherapeutic approaches in melanoma, and the opportunity to evaluate the mechanism of action suggest neoadjuvant trial evaluation for each of the new candidate agents and combinations of interest. Several neoadjuvant trials have been conducted in the phase II setting, which have illuminated the mechanism of IFN-α, as well as providing insight to the effects of anti-CTLA4 blocking antibodies. These agents (anti-CTLA4 blocking antibody ipilimumab, and BRAF inhibitor vemurafenib) are likely to be followed by other immunotherapies that may overcome the PD-1 checkpoint (anti-PD1 and anti-PDL-1) as well as other molecularly targeted agents such as the BRAF inhibitor dabrafenib and the MEK inhibitors trametinib, selumetinib, and MEK162 in the near future. Evaluation of the clinical role of these agents as adjuvant therapy will take years to accomplish to ascertain the relapse-free survival benefits and overall survival benefits of these agents, but neoadjuvant exploration may provide early critical evidence of the therapeutic benefits, as well as clarifying the mechanisms of these agents alone and in combination.