PD-1 Inhibition in Advanced Myeloproliferative Neoplasms

The researchers propose a Simon-two stage design for this study. The researchers will test pembrolizumab at the FDA approved dose (in head and neck cancer) of 200mg dose administered via intravenous infusion over 30 minutes given every 3 weeks. Nine patients will be enrolled in the first stage of the Simon-two stage design, and 15 in the second stage. A treatment cycle is 3 weeks and the core study period is 6 cycles. Response assessment by established consensus criteria will be used to assess response after 6 cycles in order to determine if the trial will progress to the second stage and for the purpose of determining the primary endpoint. In addition, allowed will be a maximum of ten patients with accelerated or blast phase disease (MPN-AP/BP) who are refractory or intolerant to conventional therapies such as decitabine, and in which hematopoietic stem cell transplant is not a therapeutic option (exploratory cohort), to enroll in the study as a separate exploratory cohort. These patients can be enrolled during stage 1 or 2 and will be analyzed separately from the primary cohort population. Exploratory biomarkers will be obtained from enrolled patients at baseline, cycle 3 and cycle 7 and at 1 year of therapy. Patients that obtain at least a clinical improvement after 6 cycles of therapy can continue receiving pembrolizumab until evidence of disease progression, unacceptable toxicity, and patient or physician decision for a maximum of 2 years.