Myelodysplastic Syndrome, Unclassifiable

This study will be conducted as a phase 1/2 study of safety and preliminary efficacy of pacritinib in combination with azacitidine for IPSS-M moderate low to very high risk MDS. Phase one will be a 3 + 3 design to assess the dose for the phase two portion. The phase two portion will employ a simon min-max two-stage design whereby fifteen patients will be enrolled in the first stage then ten more if at least two patients in stage one have a response. The dosing of pacritinib for the phase two study will be based on the phase one findings. Standard dosing of azacitidine will be used. A correlative study will be conducted in conjunction with the trial where the investigators will measure whole blood collected pre-treatment and at four days post-treatment to measure intracellular flow and phosflow to detect JAK/STAT, NF-κβ, and AKT/mTOR signaling in patient samples and how treatment affects these pathways.