16yo M presented 1/2025 with WBC 554 k/mcl, Hgb 7.7 g/dl, Plt 251 k/mcl. No blasts in PB or marrow by flow cytometry. BCR/ABL FISH was positive. Started on dasatinib 100mg once daily for treatment of chronic phase CML. Initial count nadir about 3-4 weeks into treatment (plt nadir 67k, normalized to 300s without any dose adjustments or medication hold, ANC remained normal). At 3 month lab check in early April, found to have profound cytopenias with ANC 160 and PLT 27. Dasatinib 100 mg daily was held.Peripheral blood BCR/ABL PCR was 33% at diagnosis and 2% at 3 month check.After a 2 week hold of dasatinib, platelets were uptrending to the 40s but then dropped again to <10. ANC has not shown any response.Bone marrow biopsy/aspirate after 4 week dasatinib hold showed low cellularity (10-20%) without an expanded blast population by morphology or flow, however FISH shows 59.5% of cells are positive for BCR/ABL1 rearrangement and marrow RT PCR shows 25% BCR ABL transcripts.PB BCR/ABL PCR now 4.9% after 7 week dasatinib hold. ANC remains <100 and requiring platelet transfusions 2-3x/week.Seeking input regarding use of growth factor (GCSF and/or TPO agonists), role of HCT, and any other suggestions.Thank you!