Gain-of-function D816V point mutation within the kinase domain of the transmembrane receptor KIT is found in the great majority of patients with systemic mastocytosis (SM) and is attractive therapeutic target. Twenty patients with SM were enrolled during 2003–2005 in phase II clinical trial with imatinib mesylate (400mg daily), a KIT inhibitor. Median time on therapy was 9 months (range, 0.5 – 44+). Only 1 patient, with D816V KIT mutation-negative FIP1L1-PDGFRα-negative SM-HES, achieved complete remission (now lasting for 44 months). Six other patients reported symptomatic improvement, including 2 with D816V KIT mutation-positive SM (one reported improvement in diarrhea and the other in fatigue). Other patients had no benefit. Imatinib was relatively well tolerated. Our study confirms that imatinib therapy does not result in appreciable clinical activity in patients with D816V mutation-positive SM, but may result in a significant benefit in occasional patient with D816V mutation-negative SM.

Using current treatment regimens, over 90% of patients with acute promyelocytic leukemia will achieve complete remission (CR). However, approximately 30% of these patients will relapse, including a small proportion who will develop extramedullary disease (EMD). In this study, we investigated the incidence of EMD in 263 patients with APL who were treated at our institution from January 1990 to May 2008. With a median follow-up of 31 months (range 2 days–203 months), 8 (3%) patients developed EMD. The most commonly affected site was the central nervous system (n = 7). Before developing EMD, one patient had achieved CR with a chemotherapy-only regimen, six patients had achieved CR with all-trans-retinoic acid (ATRA)-based regimens, and one patient had achieved CR with an ATRA plus arsenic trioxide (ATO)-based regimen. The EMD conferred a poor prognosis; five patients died within 4 months of developing EMD. The molecular status did not predict EMD; four patients had a negative PCR for the PML-RARA transcripts prior to relapse with EMD. In conclusion, the incidence of EMD is low. We were unable to identify any specific factors that could predict the development of EMD.

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Background. Different types of BCR-ABL fusion mRNAs can be found in pts with CML due to different genomic breakpoints and alternative splicing. The two major forms join ABL exon 2 with exons 13 or 14 of BCR, resulting in two main transcripts, b2a2 and b3a2, respectively, that codify for a p210 protein present in the majority of CML patients. b3a2 is more frequent in newly diagnosed patients than the b2a2 transcript, and occasionally both transcripts may be present. The clinical significance of the specific transcript among CML pts treated with imatinib has not been clearly established, and some have suggested that b2a2 may be associated with better outcome. (Blood2006108: Abstract 4780) Genet.Mol. Res.4(4): 803–811 (2005)Journal of Clinical Oncology, 2007 Vol 25, No 18S (June 20 Supplement), 2007: 7043. Purpose: To determine if there is a difference in outcome after imatinib therapy in CML pts according to their BCR-ABL transcript. Methods: We analyzed 480 pts with CP CML treated with imatinib, 251 receiving imatinib as frontline therapy and 229 after interferon (IFN) failure. Molecular response was evaluated using RT PCR every 3 months (mo). Results: The median follow-up was 62 mo (range 1–92 mo) Median age was 51 years (range 15–84). Overall, 187 of 480 (39%) pts expressed b2a2, 234 (49%) b3a2, 55 (11%) expressed both, and 4 (1%) expressed e1a2. The rates of major and complete cytogenetic response were similar for pts with b3a2 and b2a2, both in the newly diagnosed and the post-IFN failure: CCyR 91% for b3a2 and 89% for b2a2 in frontline, and 72% and 78%, respectively in the post-IFN failure group. However, among 433 pts evaluable for molecular response, transcript levels were significantly lower at 3, 6 and 12 months from start of therapy for pts with b3a2 compared to those with b2a2 (Table 1). Table 1. Median BCR-ABL transcript levels over time by transcript type 3 months 6 months 9 months overall b2a2 1.8284 0.318 0.186 0.0464 b3a2 0.5175 0.0553 0.0352 0.0033 p-value 0.001 <0.001 <0.001 <0.001 This resulted in a significantly higher probability of achieving a major molecular remission (MMR) and complete molecular remission (CMR; ie, undetectable transcript levels) for pts with the b3a2 transcript (Table 2). Table 2 Molecular Response in patients Post IFN failure and patients newly treated Transcript No.* MMR** (%) P value CMR*** (%) P value *Number of evaluable patients. Dx=Diagnosis New Dx b2a2 106 63 59 26 25 New Dx b3a2 115 88 77 0.008 54 47 0.002 Post IFN b2a2 62 21 34 10 16 Post IFN b3a2 97 61 63 0.001 41 42 0.001 There was a trend for an improved transformation-free survival for pts with b3a2 compared to those with b2a2 (4-yr rates 98% vs 93%, respectively, p=0.08) and event-free survival (94% vs 87%, p=0.37). Although fewer pts co-expressed both transcript types, they behaved like the pts with b3a2. Conclusion: Pts with the b3a2 transcript have a better molecular response to imatinib that those with b2a2. This prognostic factor should be considered when evaluating response to therapy.

Homoharringtonine is an alkaloid inhibitor of protein synthesis with activity in myeloid malignancies. We report a phase II pilot study of homoharringtonine in myelodysplastic syndrome (MDS). Induction consisted of homoharringtonine at 2.5 mg/m2 via continuous infusion for seven days. Maintenance was given every 4 weeks. Nine patients were enrolled: five with refractory anaemia with excess blasts, two with refractory anaemia with excess blasts in transformation, one each with refractory anaemia and chronic myelomonocytic leukaemia, respectively. Median age was 70 years (55–84) and 6 (66%) were male. Per International Prognostic Scoring System (IPSS) two patients were intermediate-1, five intermediate-2 and two high-risk. Median chemotherapy courses were one (1–3). One patient (11%) responded with complete hematologic and cytogenetic remission after one course. Eight patients did not respond (four had stable disease, two progressed to acute leukaemia and two died during induction - from aspergillus pneumonia and intracerebral haemorrhage, respectively). Grade 3/4 myelosuppression seen in 56% (5/9). Serious non-hematologic toxicities included one case of grade 4 left bundle branch heart block and one grade 3 nephrotoxicity. Median time between courses was 42 days (35–72 days). In conclusion homoharringtonine might have clinical activity in some patients with MDS.