Immunotherapy with HD-IL-2 has produced durable benefit in 10% of patients with metastatic
cutaneous melanoma. The antitumor activity of IL-2 has been limited at least in part by
immunosuppressive and immune-regulatory forces within the tumor microenvironment. Antibodies
against CTLA4 (e.g. ipilimumab), PD1 and its ligand (PD-L1) produced long-term benefit in
approximately 20-40% of patients with advanced melanoma. In addition, the combination of
ipilimumab with the anti-PD1 antibody, nivolumab, has shown tumor responses in up to 60% of
patients with advanced melanoma. These findings have led to FDA approval of ipilimumab and
nivolumab as an indication for treatment of patients with advanced melanoma and nivolumab for
other cancers. While these data are exciting, only a few patients enrolled to the prior
studies had metastatic MCM or ALM. There is no prospective immunotherapy studies conducted in
MCM or ALM-specific population. Therefore the activity of the ipilimumab + nivolumab
combination in these subsets or patients remains unknown
Reliable predictive biomarkers for the use of immune checkpoint inhibitors are needed to
identify pretreatment those patients most likely to respond and early on in treatment assays
could help identify mechanisms of tumor response and resistance necessary to improve therapy.
Although tumor PD-L1 expression in tumor confers higher treatment response rate, responses to
nivolumab or nivolumab + ipilimumab alone were noted in 55% and 41% of patients,
respectively, with PD-L1- tumors. Therefore, more reliable predictive biomarkers are needed.
Recently, extensive studies on metastatic colorectal cancer have demonstrated that a new
scoring system as well as density of immune cells infiltrates at the center of the tumor and
its invasive margin, described as Immunoscore, could accurately separate a group of patients
with high Immunoscore with improved DFS, and OS from those with low Immunoscore where the
histopathological staging system cannot. A recent study has also demonstrated relationship
between degree of pre-treatment CD8+ tumor infiltrating lymphocytes (TILs) infiltration and
PD-L1 expression at the invasive margin of the advanced cutaneous melanoma and improved
long-term clinical benefits in patients with advanced melanoma who received pembrolizumab
monotherapy. Further, there appeared to be an association between tumor response and
clonality of the immune infiltrate based on a next-generation sequencing method used to
evaluate T-cell receptor rearrangement pre- and in response to checkpoint inhibitor therapy.
Also, high mutational burden correlated with overall survival in patients with cutaneous
melanoma treated with ipilimumab or lung cancer treated with anti-PD1. However, the biology
of MCM and ALM are distinct from cutaneous melanoma at multiple levels. Consequently, the
utility of predictive biomarkers developed for cutaneous melanoma remains unknown.