Dasatinib In Waldenström Macroglobulinemia

Inclusion Criteria: * Participants must meet the following criteria on screening examination to be eligible to participate. Screening evaluations including consent, physical exam, and laboratory assessments will be done within 30 days prior to Cycle 1 Day 1. Bone marrow biopsy \& aspirate, and CT C/A/P will be done within 90 days prior to Cycle 1 Day 1. * Clinicopathological diagnosis of Waldenstrom's Macroglobulinemia * Known tumor expression of mutated MYD88 performed by a CLIA certified laboratory. * Participants must have a BTKCys481 and/or PLCγ2 mutation. Genomic alterations must be confirmed via sequencing performed at NeoGenomics Laboratories * At least one previous therapy, with ibrutinib as the most recent treatment. Participants may remain on ibrutinib therapy during screening. A 1 day washout before starting dasatinib is required. * Documented disease progression on last regimen (ibrutinib) per the Sixth International Workshop on WM. One or more of the following: * 25% increase in serum IgM level with at least 500 mg/dL absolute increase from nadir with re-confirmation * Progression of clinically significant disease related symptoms * Symptomatic disease meeting criteria for treatment using consensus panel criteria from the Second International Workshop on WM \[26\]. One or more of the following: * Constitutional symptoms * Progressive or symptomatic lymphadenopathy or splenomegaly * Hemoglobin \<10 g/dL * Platelet count \<100 k/uL * Symptomatic periphe…