2 Drug Bosutinib Imatinib Mesylate Nilotinib Dasatinib Dasatinib + IFN 2a Dasatinib Case Reports in Hematology Table 1: A brief summary of the CML treatment schedule including the drug, dosage, duration, and response/event. Dose 400 mg/day 400 mg/day 2 × 400 mg/day 100 mg/day 140 mg/day + 3 MU/day 100 mg/day Duration 14 months 2 months 4 months 3 months 3 months 1 month Response/event Complete cytogenetic response Hematologic adverse event (pancytopenia) Molecular relapse No molecular response, minor cytogenetic response Blastic crisis (BP) Leukemic transformation 2. Case Presentation A 48-year-old male patient was admitted to our Hematology Department with the complaints of lassitude, fatigue, and weight loss (15 kg within six months) in December 2008. Splenomegaly was found in the physical examination. A bone marrow biopsy revealed hypercellular bone marrow, increased ratio of myeloid/erythroid (M/E) precursors, and was compatible with chronic myeloproliferative disorder. The diagnosis of high-Sokal risk chronic myeloid leukemia (CML) was revealed after the detection of the Philadel- phia chromosome in all metaphases in the bone marrow cytogenetic analysis. Bosutinib was then started within the context of BELA randomized clinical trial, afterwards his leukocyte count was decreased from 32.8 × 103/µL to 2.0 × 103/µL (normal range: 3.60–10.00) within two months and went into remission. However, in January 2010, cytogenetic relapse occurred, and the patient had been placed on imatinib mesylate treatment at a dose of 400 mg once daily. He became pancytopenic just after two months of imatinib therapy. Nilotinib was then initiated at a dose of 400 mg twice daily peroral in 2010 March, and the pancytopenia was improved. However, under nilotinib treatment, 30 copies/1 µg RNA P210 BCR-ABL fusion transcripts were detected via RT-PCR analyses in July 2010. Meanwhile, his leukocyte count increased from 3.8 × 103/µL to 27.3 × 103/µL. Dasatinib 100 mg daily peroral was therefore initiated. Under dasatinib treatment, 7177 copies/1 µg RNA P210 BCR-ABL fusion transcripts were detected via RT- PCR analyses in October 2010. Bone marrow biopsy in January 2010 revealed hypercellular (90–95%) bone marrow, increased M/E ratio, and megaloblastic-dysplastic changes in erythroid precursors. Blastic cell ratio was <5%. Con- ventional cytogenetics at that time revealed Philadelphia chromosome in 26 metaphases out of 47 metaphases. IFN- 2a was added to the TKI treatment as a part of the combination regimen. He applied to emergency room with the complaints of rectal bleeding lasting for 1 month and fever for 1 week. His blood count were as follows; Hb; 4.2 gr/dL (normal range: 4.3–10.3), WBC; 27.5 × 103/µL, platelet; 13 × 103/µL (normal range: 156–373). RBC and platelet suspensions replacement were performed. Steroid- induced diabetes mellitus has also complicated the clinical status. Physical examination revealedtachycardia, dyspnea, and tachypnea. Liver and spleen were palpable below the costal margins. Abdominal magnetic resonance imaging re- vealed perianal ﬁstula. His medications included dasatinib 140 mg and IFN-2a 3 MU combination. During the follow- up, the patient became pancytopenic again, and IFN-2a was stopped. Dasatinib was also stopped for a short time because of the recurrence of the active rectal bleeding ascribed to the drug. A bone marrow biopsy in 2011 February revealed increased blastic cells compatible with the blastic crisis of CML. Dasatinib 100 mg daily was initiated again. Under the dasatinib treatment, he was always leukopenic. WBC count levels ﬂuctuated between 0.8–2.1 × 103/µL. One month later, a control bone marrow biopsy revealed diﬀuse blastic inﬁltration, increased reticulin ﬁbres (grade 2/3), and >20% blastic cells in the aspiration smears. Therefore, cytosine arabinoside 100 mg/m2 (200 mg) daily for seven days was administered intravenously. He then underwent an allo- HSCT from an identical sibling female donor. ABO incom- patibility was not documented between the patient and the donor. Prior to transplantation, his blood count revealed Hb: 9.2 g/L, WBC: 0.9 × 109, PLT: 43 × 109/L. His conditioning regimen consisted of intravenously (IV) busulphan (48 mg/6 hours on days −5, −4, −3), IV ﬂudarabine (25 mg/m2, on days −8, −7, −6, −5, −4, −3) and IV methotrexate (25 mg on day +1 and 15 mg on days +3, +6, +11). Allo-HCST with reduced intensity regimen was used due to the patients’ poor performance. Peripheral stem cell with a volume of 258 cc (9.4 × 108 mononuclear cell/kg; 6.05 × 106 CD34+ allogeneic hematopoietic stem cell/kg) was transplanted. The stem cell infusion was successful without adverse events. He achieved a neutrophil and platelet engraftment on days +11 and +15, respectively. Posttransplant DLI was performed in July 2011. The patient is still being followed in aplastic pancytopenia state without any sign of remission. There have been no serious episodes of infection, and the patient has had no evident GVHD throughout his course. During the clinical course of this CML patient, no Abl kinase domain mutation has been detected. The methods for the mutation analyses were as follows. RNA isolation and cDNA synthesis for the mutation analyses were per- formed. The patient’s material was stored at −80◦C after homogenization in Trizol reagent (Invitrogen). Total RNA was isolated according to Trizol RNA isolation protocol. 1 µg of total RNA was used for cDNA synthesis by using random hexamers and MMLV reverse transcriptase (Fermentase) according to the protocol of the manufacturer. Nested PCR and sequencing analysis for the mutation analyses were performed. We used a nested-PCR approach for the ampliﬁcation of Abl kinase domain.