Hochhaus, Andreas

TPS6641 Background: Hydroxyurea is widely used to treat patients with high-risk PV and ET. However, some patients are either clinically resistant to hydroxyurea or have unacceptable side effects, supporting the need for active therapeutic options in this setting. SAR302503 is an orally administered selective JAK-2 inhibitor that reduced symptom burden and provided a durable clinical benefit, including a reduction in the JAK2V617F allele burden, with an acceptable safety profile in a Phase 1/2 trial of patients with primary myelofibrosis (MF), post-PV MF, or post-ET MF (J Clin Oncol 2011;29:789; Pardanani, ASH 2011; Abs 3838). Based on the results in MF, in October 2011 we initiated a Phase 2 trial to evaluate SAR302503 for the treatment of patients with PV and ET who are resistant or intolerant to hydroxyurea (NCT01420783; ARD12042). Methods: Eligibility criteria include age of at least 18 years, ECOG PS 0–2, and hydroxyurea resistant PV or ET as defined by European LeukemiaNet Consensus Criteria (Blood 2009;113:4829). Patients are being randomized (1:1:1) to receive 100, 200, or 400 mg of SAR302503 orally once daily in consecutive 28-day cycles for at least 8 cycles in the absence of progression or unacceptable toxicity. The primary end points will be assessed after the completion of 8 cycles and are: for PV, the proportion of patients maintaining a hematocrit below 45% without phlebotomy for at least 3 months; for ET, the proportion of patients with a platelet count lower than 400 × 109/L for at least 3 months. Secondary objectives include safety, response rate, pharmacokinetics, pharmacodynamics as measured by JAK2V617F allele burden and STAT3 phosphorylation inhibition, assessment of disease-related symptoms, and quality of life. Enrollment of the planned total of 90 patients is ongoing at approximately 45 sites globally. Twelve patients have been enrolled as of January 2012.

Abstract Abstract 3895 Poster Board III-831 A genome-wide single nucleotide polymorphism (SNP) screen led to the identification of 11q aUPD in patients diagnosed with various subtypes of myeloproliferative neoplasms (MPN), e.g. chronic myelomonocytic leukemia (CMML), atypical chronic myeloid leukemia (aCML) and myelofibrosis (MF) (Grand et al., Blood 2009;113:6182). Further molecular analyses revealed acquired activating point and length mutations in CBL exons 8 and 9 in 10% of CMML, 8% of aCML and 6% of MF cases. Most variants were missense substitutions in the RING or linker domains that abrogated CBL ubiquitin ligase activity and conferred a proliferative advantage to 32D cells overexpressing FLT3. In this study, 160 patients with BCR-ABL and JAK2 V617F negative MPNs were screened for CBL mutations by PCR and direct sequencing. Eighteen known (Y371H, L380P [2x], C381R, C381Y [2x], C384Y, C396Y, H398P, H398Q, W408C, P417H, F418L, R420Q [5x]) and four new (F378L, G397V, I423N, V430M) missense mutations affecting fourteen residues were identified in 20 patients. Two patients harbored two different mutations. The clinical phenotype could be characterized more precisely in 17 patients. Median age was 68 years (range 59–85) with a slight female predominance (f, n=10; m, n=7). Striking hematological features were leukocytosis (14/17; 82%; median 29,000/μl, range 4,500-141,000) with continuously left-shifted granulopoiesis (blasts, promyelocytes, myelocytes, metamyelocytes) in 85% and elevated monocytes (median 2,500/μl, range 630-10,656) >1,000/μL in 88% (15/17) of patients. Eosinophilia (>1,500/μL) was rare (3/17, 18%). Anemia (normal values: f, Hb <12g/dL; m, Hb <14g/dL) was present in all 17 patients (f, median 10g/dL, range 8.7-11.8; m, median 11.2g/dL, range 8.6-12.9). Platelets did not exceed 300,000/μL in any patient while 11/17 (65%) patients presented with thrombocytopenia (median 125,000/μL, range 18,000-271,000). Splenomegaly was present in 11/17 patients (65%) and LDH was elevated (median 304U/L, range 189-729) in 9/17 patients (52%). Bone marrow histology and immunohistochemistry were available from 12 patients. Relevant features were hypercellularity, marked granulopoiesis and microlobulated megakaryocytes without clusters in 11/12 patients (92%), respectively. Increased fibres were seen in 8/12 (67%) patients of whom one showed severe fibrosis. Clinical follow-up was available from 17 patients. Thirteen patients (76%) have died because of progression to secondary acute myeloid leukemia/blast phase (n=7), cytopenia-related complications (n=2) or for unknown reasons (n=4) after a median of 23 months (range 3-60) following diagnosis. In conclusion, point mutations of CBL exons 8 and 9 are present in approximately 6-12% of BCR-ABL and JAK2 V617F negative MPNs. They are associated with a distinct clinical and hematological phenotype presenting with myeloproliferative features allowing diagnosis of a proliferative subtype of CMML rather than aCML or MF in the majority of cases. Patients with left-shifted leukocytosis, monocytosis, anemia and lack of thrombocytosis who are negative for BCR-ABL and point or length mutations of JAK2 should be routinely screened for CBL mutations. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: Nilotinib, a 2nd-generation BCR-ABL inhibitor, is 20–30 times more potent than imatinib in vitro. A phase II, open-label study of safety/efficacy of nilotinib in pts with imatinib-resistant/intolerant Ph+ CML-CP or -AP was reported. Planned starting dose was 400mg BID, with escalation to 600mg BID if response was inadequate. The objective of the post-hoc analysis was to evaluate safety/efficacy of nilotinib 600mg BID in CML-CP pts who had dose escalation. Methods: Starting dose was 400mg BID. If response was inadequate (failure to achieve complete hematologic response [CHR] by 3 mos, minimal cytogenetic response [CyR] by 6 mos, or major cytogenetic response [MCyR] by 12 mos; loss of HR, CyR, or progression), nilotinib to 600mg BID dosing was permitted. Imatinib resistance was defined as treatment with imatinib ≥600 mg/d with disease progression (≥50% increase in WBC, blasts, basophils, or platelets) or no HR in peripheral blood and/or bone marrow after 4 wks. Results: Of 320 enrolled pts in CP, 269 remained on nilotinib 400mg BID; 51 pts were dose-escalated to 600mg BID for inadequate responses (mean age 57.7 yrs; 68.6% male). All pts met the study criteria for imatinib resistance. Prior imatinib dose was ≥600mg QD in 98% pts and ≥800 mg QD in 53%. 43/51 (84%) pts had no baseline CHR; 38% had no prior history of complete cytogenetic response (CCyR). 35% had prior MCyR. Median time to dose escalation was 169 (114–211) d. 14 (27.5%) pts remain on therapy; median time to discontinuation from study was 307 (235–414) d. 5 pts with disease progression and no deaths were observed among pts who received 600mg BID. CHR was achieved in 58% of evaluable pts without CHR at baseline (n=43). MCyR occurred in 29% of evaluable pts (15/51) on 600mg BID; 10% (5/51) CCyR. Disease progression was low, occurring in 10% (5/51) of pts on 600mg BID. Median time to progression for CP pts on 600mg BID was 12 mos, substantially less than for pts who stayed on 400mg BID (median not observed yet, at least 20 mo). Nonhematologic AEs in 600mg BID pts were similar to those reported for the entire CP cohort from the phase II study. Grade 3/4 hematologic lab abnormalities were: anemia 13.8%, neutropenia 7.9%, thrombocytopenia 13.7%. Hyperglycemia and elevated bilirubin occurred in 6% and 10% of pts, respectively, on 600mg BID. Conclusions: Some HR and CyR after dose escalation to 600mg BID were observed. Safety/tolerability for 600mg BID were similar to the entire CP cohort. Based on these preliminary data, nilotinib dose escalation to 600mg BID in imatinib-resistant Ph+ CML-CP pts may be effective in pts with inadequate responses to 400mg BID. As might be expected in a more resistant population, response duration was shorter than reported for the phase II CP cohort. Additional follow-up is necessary. Use of 600mg BID is not currently recommended for imatinib-resistant CML-CP pts outside clinical studies.

Abstract Nilotinib, an orally bioavailable, selective Bcr-Abl tyrosine kinase inhibitor, is 30-fold more potent than imatinib in pre-clinical models, and overcomes most imatinib resistant BCR-ABL mutations. In this phase 2 open-label study, 400 mg nilotinib was administered orally twice daily to 280 patients with Philadelphia chromosome–positive (Ph+) chronic myeloid leukemia in chronic phase (CML-CP) after imatinib failure or intolerance. Patients had at least 6 months of follow-up and were evaluated for hematologic and cytogenetic responses, as well as for safety and overall survival. At 6 months, the rate of major cytogenetic response (Ph ≤ 35%) was 48%: complete (Ph = 0%) in 31%, and partial (Ph = 1%-35%) in 16%. The estimated survival at 12 months was 95%. Nilotinib was effective in patients harboring BCR-ABL mutations associated with imatinib resistance (except T315I), and also in patients with a resistance mechanism independent of BCR-ABL mutations. Adverse events were mostly mild to moderate, and there was minimal cross-intolerance with imatinib. Grades 3 to 4 neutropenia and thrombocytopenia were observed in 29% of patients; pleural or pericardial effusions were observed in 1% (none were severe). In summary, nilotinib is highly active and safe in patients with CML-CP after imatinib failure or intolerance. This clinical trial is registered at http://clinicaltrials.gov as ID no. NCT00109707.