Will PD-1 inhibitors be msed for Mastocytosis?
By Warren R. Heymann, MD
May 8, 2016
Kuklinski L, Kim J. Expression of PD-L1 in mastocytosis. J Am Acad Dermatol 2016; 74: 1010-2.
The authors evaluated 16 specimens from 12 patients with mastocytosis, using immunohistochemical stains for PD-L1, CD-117, and mast cell tryptase on all specimens. Of the12 patients, 8 were male, 4 female, with an age range of 3 days to 86 years old. Three patients had solitary mastocytomas, 1 with urticaria pigmentosa, 2 with diffuse cutaneous mastocytosis, 2 with telangiectasia macularis eruptive perstans, 1 with systemic mastocytosis, and 3 were not specified as to mastocytosis type. A strong, diffuse PD-L1 stain was identified in all mastocytosis specimens, regardless of subtype.
This, of course, raises the question as to whether PD-1 inhibitors such as pembrolizumab or nivolumab would be of value in cases of extensive cutaneous and/or systemic mastocytosis. As of today (May 8, 2016) there are no such reports. We are most familiar with these checkpoint inhibitors for the treatment of melanoma. They are also being actively studied and utilized in other tumors such as non-small cell lung cancer. The value of these drugs is expanding beyond the borders of solid tumors and melanoma. According to Kasenda et al (Beginning of a novel frontier: T-cell-directed immune manipulation in lymphomas. Expert Rev Hematol 2016; 9: 123-35):
“In heavily pretreated Hodgkin lymphoma, PD-1-directed treatment has led to high remission rates. Several studies are now conducted also including diffuse large B-cell and follicular lymphoma.”
With the presence of PD-L1 in all cases of mastocytosis noted in this study, we will likely not have to wait long before we learn of their therapeutic value in mastocytosis.
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