Durable Hematologic Responses Research Articles

Opportunistic Infections Are Uncommon with Dasatinib in Patients with Chronic Myeloid Leukemia in Chronic Phase (CML-CP).

Abstract 1120Poster Board I-142 BACKGROUNDDasatinib is a tyrosine kinase inhibitor that can achieve rapid and durable hematological, cytogenetic, and molecular responses in patients with CML-CP after resistance or intolerance to imatinib. Three years of follow-up data have been accumulated, with progression-free survival rates of 73% reported for second-line dasatinib 100 mg once daily (the currently approved dose for CML-CP). In addition to BCR-ABL, dasatinib inhibits Src family kinases (SFKs) and thereby mitigates T-cell receptor-mediated signaling. Dasatinib may have unique immunomodulatory properties. Modulation of CD8+ T-cell intracellular signal transduction, cellular proliferation, and cytokine production by dasatinib has been previously reported in vitro (Fei F. Exp Hematol. 2008;36(10):1297-308). Also, dasatinib has been shown to induce expansion of T-cells and NK cells in the clinic, an effect that was associated with achieving a complete molecular response (Mustjoki S. Leukemia. 2009;23(8):1398-405). Opportunistic infections (OI) like herpes zoster infections (HZV) have been previously reported with imatinib, albeit at a low rate (Mattiuzzi GN. Clin Cancer Res. 2003;9(3):976-80). AIMTo determine the frequency of OI in clinical trials of dasatinib in CML-CP. METHODSData from phase II CA180-013 and CA180-017, and phase III CA180-034 trial databases of 1150 CML-CP patients, collectively, were reviewed. A search for infection adverse events was conducted, and entries related to opportunistic pathogens were identified and tabulated. The follow-up time is ≥3 years for all patients in the phase III study and 2 years in the phase II studies. The median time on dasatinib treatment for patients treated with 100 mg once daily is 31 months, and for other doses is 25 months. RESULTSOf the 165 patients treated with dasatinib 100 mg once daily, only one grade 3–4 OI was identified (incidence <1%): a grade 3 HZV infection. In addition, there were 18 cases (11%) of grade 1–2 herpes simplex (HSV), 3 HZV, and one mycobacterial infection. Thirteen of the HSV cases were reported as not related to dasatinib treatment. Among 985 patients treated with other dosing schedules (50 mg twice daily, 70 mg twice daily, or 140 mg once daily), 7 cases (<1%) of grade 3–4 OIs were identified: 1 cytomegalovirus, 2 HSV, 1 HZV, 2 pneumocystis, and 1 unspecified fungal infection. There were 87 (9%) grade 1–2 HSV cases reported in the other dosing arms, but 62 were deemed not associated with dasatinib. There were 23 reports (2%) of grade 1–2 HZV infection with other doses, and one case of a grade 2 cytomegalovirus infection. CONCLUSIONOur analysis indicates that OIs are rare in patients with CML-CP treated with dasatinib. Most of the infections associated with opportunistic pathogens were grade 1–2. Thus, despite in vitro data suggesting immunosuppressive properties of dasatinib, there do not seem to be adverse clinical consequences with this agent. DisclosuresKantarjian:Bristol-Myers Squibb: Research Funding; Novartis: Research Funding. Borthakur:Bristol-Myers Squibb: Speakers Bureau; Novartis: Speakers Bureau; Celgene: Speakers Bureau. Bahceci:Bristol-Myers Squibb: Employment. Szatrowski:Bristol-Myers Squibb: Employment. Damokosh:Bristol-Myers Squibb: Employment. Cortes:Bristol-Myers Squibb: Research Funding.

Safety and Efficacy of Subcutaneous-Administered Omacetaxine Mepesuccinate in Imatinib-Resistant Chronic Myeloid Leukemia (CML) Patients Who Harbor the Bcr- Abl T315I Mutation–Results of An Ongoing Multicenter Phase 2/3 Study.

Abstract 644Background: Omacetaxine is a first-in-class cetaxine with clinical activity against Ph+ CML and a mechanism of action independent of tyrosine kinase inhibition. Currently available tyrosine kinase inhibitors (TKIs) have not demonstrated activity in CML patients (Pts) who harbor the Bcr-Abl T315I mutation. Study Goals: To evaluate the safety and efficacy of subcutaneously (SC) administered omacetaxine in Pts with imatinib (IM)-resistant T315I+ Ph+ CML. Methods: Eligible Pts include adult CML Pts in chronic, accelerated, or blast disease phase (CP, AP, BP) with a confirmed Bcr-Abl T315I mutation and resistance to IM therapy. Induction schedule: 1.25 mg/m2 SC omacetaxine twice daily for 14 days every 28 days until hematologic response. Maintenance dosing: 1.25 mg/m2 SC omacetaxine twice daily for 7 days every 28 days. Study Results: To date, 90 Pts have been enrolled, with data available for analysis on 66 Pts (40 CP, 16 AP and 10 BP). The median age was 58 yrs (19-83) with 70% male Pts and a median disease duration of 54 mo (5-285). All Pts failed prior IM therapy, and 79% failed two or more prior TKIs. The presence of baseline T315I mutation was confirmed in all Pts. Baseline clonal evolution was evident in 10 (25%) CP, 6 (38%) AP, and 7 (70%) BP Pts. Eight CP Pts entered the study in CHR. The median follow-up for all Pts was 6.4 mo (0.2 to 29.6). Efficacy: In CP Pts, CHR was achieved in 26 Pts and maintained in 8 Pts for an overall CHR rate of 85%; the median duration of CHR was 7.7+ mo (1.7 to 23.6). Overall cytogenetic response was 27.5% with 6 (15%) Pts achieving a major cytogenetic response (MCyR, 4 complete, 2 partial). The median duration of MCyR was 6+ mo (0.8 to 16.1). Major molecular response was achieved in 15% of Pts and a reduction of baseline T315I mutated clone occurred in 56.7% of CP Pts. In AP Pts, overall hematologic response was achieved in 6 (37.5%) Pts with 5 CHR and 1 return to chronic phase (RCP). Median duration of response was 3.9+ mo (1.7 to 14.8). One AP Pt achieved a complete cytogenetic response; duration 1.9+ mo. In BP Pts, overall hematologic response was achieved in 3 (30%) Pts with 2 CHR and 1 RCP. The median overall survival for CP Pts has not been reached and 35 (88%) Pts were alive at the time of data cut- off. The median overall survival was 18.8 mo for AP and 1.8 mo for BP Pts. Median time to progression was 11.2, 3.1, and 1.2 mo for CP, AP, and BP Pts, respectively. Safety: Grade 3/4 related events occurred in 45 of 66 (68%) Pts. The most commonly reported events were thrombocytopenia (58%), anemia (36%) and neutropenia (33%). Non-hematologic toxicities were primarily grade 1/2 with the most frequently reported events of diarrhea (44%), fatigue (35%), pyrexia (32%), nausea (26%), and asthenia (21%). Grade 3/4 non-hematologic toxicities were uncommon with no events occurring in >5% of Pts and infection (3%) the most common event. Treatment delays occurred in approximately 50% of the Pts with median duration of approximately 12 days for all disease phases and cycles (CP=12, AP=10, and BP=12 days). The primary causes of delay were thrombocytopenia, neutropenia and pancytopenia. Sixteen deaths occurred during the study (5 CP, 4 AP, and 7 BP).Three deaths (1 CP, 1 AP, and 1 BP) were considered to have a possible relationship to omacetaxine: sepsis, pancytopenia, and sudden death with unknown cause, respectively. Conclusions: Omacetaxine administered by subcutaneous injection produces durable hematologic and cytogenetic responses with a safety profile consisting mainly of hematologic toxicities. Omacetaxine may provide a treatment option for this patient population who currently has no available approved drug therapies. Disclosures:Cortes-Franco:ChemGenex: Membership on an entity's Board of Directors or advisory committees, Research Funding. Khoury:ChemGenex: Membership on an entity's Board of Directors or advisory committees, Research Funding. Nicolini:ChemGenex: Research Funding. Corm:ChemGenex: Research Funding. Lipton:ChemGenex: Membership on an entity's Board of Directors or advisory committees, Research Funding. Jones:ChemGenex: Research Funding. Hochhaus:ChemGenex: Research Funding. Craig:ChemGenex: Employment. Benichou:ChemGenex: Employment. Humphriss:ChemGenex: Employment. Kantarjian:ChemGenex: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Hepatic response after high-dose melphalan and stem cell transplantation in patients with AL amyloidosis associated liver disease

High-dose melphalan chemotherapy and autologous peripheral blood stem cell transplantation has been shown to result in durable hematologic response and prolonged overall survival in systemic AL amyloidosis. In this retrospective study, we evaluated clinical and hematologic responses in 69 patients with predominant liver involvement who were treated with high-dose intravenous melphalan and autologous stem cell transplantation from 1998 to 2006. Nine patients (13%) died from treatment-related mortality, similar to patients without hepatic involvement. The overall survival was 81% at one year and 61% at five years, by Kaplan-Meier estimates. A hematologic complete response was achieved by 53% (31/58) of patients at one year. A hepatic response occurred in 57% (33/58) at one year after high-dose intravenous melphalan and autologous stem cell transplantation and 63% (19/30) at two years after high-dose intravenous melphalan and autologous stem cell transplantation. In conclusion, hepatic disease improves in almost 2/3 patients treated with high-dose intravenous melphalan and autologous stem cell transplantation who have a complete or partial hematologic response to treatment.

Targeted Drugs in Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is characterized by the presence of the Philadelphia (Ph) chromosome, which results from a reciprocal translocation between the long arms of the chromosomes 9 and 22 t(9;22)(q34;q11). This translocation creates two new genes, BCR-ABL on the 22q- (Ph chromosome) and the reciprocal ABL-BCR on 9q-. The BCR-ABL gene encodes for a 210-kD protein with deregulated tyrosine kinase (TK) activity, which is crucial for malignant transformation in CML. The recognition of the BCR-ABL gene and corresponding protein led to the synthesis of small-molecule drugs, designed to interfere with BCR-ABL tyrosine kinase activation by competitive binding at the ATP-binding site. The first tyrosine kinase inhibitor (TKI), introduced into clinical practice in 1998, was imatinib mesylate. Imatinib became the first choice drug in chronic phase CML, because of its high efficacy, low toxicity and ability to maintain durable hematological and cytogenetic responses. However, approximately 20-25% of patients initially treated with imatinib will need alternative therapy, due to drug resistance, which is often caused by the appearance of clones expressing mutant forms of BCR-ABL. Second-generation TKIs have provided new therapeutic option for the patients resistant to imatinib. Dasatinib is the first, second-generation TKI, approved in the US and European Union for the treatment of CML patients with imatinib resistance or intolerance. This drug is a dual SRC-ABL kinase inhibitor, active in most clinically relevant BCR-ABL mutations, except highly resistant T315I. Other second-generation TKIs include nilotinib, bosutinib and INNO 406. Apart from TKIs, the promising group of molecules is inhibitors of Aurora family of serine-threonine kinases. One of these molecules, MK0457, has entered clinical trials, and initial reports indicate that this compound could be active in disease associated with T315I mutation. Thus, wide spectrum of new agents, with different mode of action, is currently in clinical development for CML. It is likely that combination therapy will be the best therapeutic strategy in the future.

A Phase I Study of XL019, a Selective JAK2 Inhibitor, in Patients with Polycythemia Vera

More than 98% of patients with polycythemia vera (PV) carry the activating JAK2 mutation V617F, which may play a role in the pathogenesis of PV by promoting hematopoetic cell proliferation and survival. PV is characterized by an increased red blood cell mass and is generally accompanied by increased myeloid and megakaryocytic production. Current therapy consists of supportive care measures including aspirin, phlebotomy, interferon and hydroxyurea to reduce the risk of complications of the disease such as thrombotic events. Such palliative therapy is often unsatisfactory due to side effects and the persistent susceptibility of the patients to development of thrombosis, and the failure to prevent transformation to myelofibrosis or acute leukemia. XL019 potently and selectively inhibits JAK2 (Ki of 2 nM); relative to other JAK family kinases (JAK1 Ki of 134 nM, JAK3 Ki of 195 nM and TYK2 Ki of 344 nM). Cellular selectivity of XL019 was confirmed in primary human cell assays; while EPO-stimulated pSTAT5 in primary erythroid cells was quite sensitive to XL019 treatment (IC50 of 64 nM), stimulation of T-cells with IL-2 or B-cells with IL-4 or IL-6 gave pSTAT IC50s of >800 nM in each case. Potent effects on JAK2-STAT signaling were also demonstrated in single-dose pharmacodynamic studies in xenograft tumors, including HEL92.1.7, CFPAC-1 and DU 145. XL019 is being evaluated in a Phase 1 dose escalation study in subjects with PV who have failed or are intolerant of standard therapies defined as follows: symptomatic splenomegaly in spite of current therapy, thrombocytosis with a platelet count >450K/μl, or non-controlled constitutional symptoms such as pruritus, night sweats, or weight loss. The primary objectives of this study are to determine the safety and tolerability of XL019 when administered orally either once daily, or every Monday, Wednesday, and Friday in 28-day cycles (starting doses 10 mg QD and 25 mg QMWF). Secondary objectives include determination of the pharmacokinetics and pharmacodynamics of XL019, and to evaluate clinical response using the following endpoints:hematologic response;time to hematologic response;duration of hematologic response;phlebotomy independence;change in spleen and/or liver size;change in bone marrow morphology;impact on quality of life (QOL); andimpact on functional exercise capacity.Pharmacodynamic assessments for this study include JAK2 V617F allele burden, erythropoietin-independent colony formation, changes in cytokine levels and JAK2 signaling pathways in peripheral blood mononuclear cells, and changes in bone marrow histology. Our initial findings regarding the tolerability, pharmacokinetics, pharmacodynamics, and preliminary clinical activity of XL019 in PV patients will be presented.

Nilotinib in Chronic Myeloid Leukemia Patients in Chronic Phase (CMLCP) with Imatinib Resistance or Intolerance: 2-Year Follow-up Results of a Phase 2 Study.

Background: Nilotinib is a potent and highly selective BCR-ABL kinase inhibitor approved for the treatment of Philadelphia chromosome-positive chronic myeloid leukemia patients in chronic (CML-CP) or accelerated phase (CML-AP) who are resistant or intolerant to prior therapy including imatinib.Methods: This open-label, single-arm, phase 2 study was designed to evaluate the efficacy and safety of nilotinib in CML-CP patients resistant or intolerant to imatinib. Imatinib intolerant patients with prior major cytogenetic response (MCyR) on imatinib were not eligible for this trial. Nilotinib was dosed at 400 mg twice daily with the option of dose escalation to 600 mg twice daily if responses were inadequate. Rate of MCyR was the primary endpoint. Secondary endpoints included complete cytogenetic response (CCyR), complete hematological response (CHR), duration of MCyR, survival, and safety.Results: A total of 321 CML-CP patients (71% imatinib-resistant; 29% imatinib-intolerant) were evaluated. Most patients were heavily pretreated with 72% having received more than 600 mg/day of imatinib prior to study entry. Furthermore, imatinib-intolerant patients could not have achieved prior MCyR on imatinib therapy. Median duration of prior imatinib treatment was 33 months (range 0.3–95 months). Dose reductions (25%) and discontinuations (15%) due to adverse events were infrequent on nilotinib therapy and median dose intensity (788 mg/day; range 151–1112 mg/day) closely approximated the planned dose. Median duration of exposure was 465 days (15.5 months). Overall, nilotinib therapy resulted in rapid and durable hematologic and cytogenetic responses. Of all imatinib-resistant and –intolerant patients, 58% achieved MCyR (1 month median time to MCyR), with 72% of patients having a baseline CHR achieving MCyR. The MCyR rate was 63% in imatinibintolerant and 56% in imatinib-resistant patients, respectively. Overall, 42% of patients achieved a CCyR (50% in imatinib-intolerant and 39% in imatinib-resistant patients, respectively). Responses were durable, with 84% of patients maintaining their MCyR at 18 months. Estimated overall survival (OS) rates at 12 and 18 months were 95% and 91%, respectively. Nearly half of all patients (47%) were still receiving nilotinib at the time of cut-off for data analysis. Longer follow-up has not significantly changed the safety profile of nilotinib. The most frequently reported grade 3/4 biochemical laboratory abnormalities were elevated lipase (16%), hypophosphatemia (15%), hyperglycemia (12%), and elevated total bilirubin (7%). Overall, biochemical laboratory abnormalities were transient and clinically asymptomatic. Grade 3/4 non-hematologic adverse events were infrequent with rash, headache, and diarrhea occurring in only 2% of patients. No pleural or pericardial effusions were documented during nilotinib therapy. The most common grade 3/4 hematological laboratory abnormalities included neutropenia (30%), thrombocytopenia (28%), and anemia (10%). Overall, QTcF changes greater than 60 milliseconds from baseline were infrequent, occurring in only 8 patients (2.5%), and QTcF prolongation >500 milliseconds was uncommon (<1%), occurring in only 3 patients. Brief dose interruptions were sufficient to manage most adverse events.Conclusions: Nilotinib is highly effective and produces rapid and durable responses in CML-CP patients who failed prior therapy including imatinib due to resistance or intolerance and is an important treatment option for this patient population. Nilotinib is well tolerated with minimal occurrence of grade 3/4 adverse events; safety profile has not changed with longer follow-up.

Nilotinib (formerly AMN107), a highly selective BCR-ABL tyrosine kinase inhibitor, is active in patients with imatinib-resistant or -intolerant accelerated-phase chronic myelogenous leukemia

Patients with imatinib-resistant or -intolerant accelerated-phase chronic myelogenous leukemia (CML-AP) have very limited therapeutic options. Nilotinib is a highly selective BCR-ABL tyrosine kinase inhibitor. This phase 2 trial was designed to characterize the efficacy and safety of nilotinib (400 mg twice daily) in this patient population with hematologic response (HR) as primary efficacy endpoint. A total of 119 patients were enrolled and had a median duration of treatment of 202 days (range, 2-611 days). An HR was observed in 56 patients (47%; 95% confidence interval [CI], 38%-56%). Major cytogenetic response (MCyR) was observed in 35 patients (29%; 95% CI, 21%-39%). The median duration of HR has not been reached. Overall survival rate among the 119 patients after 12 months of follow-up was 79% (95% CI, 70%-87%). Nonhematologic adverse events were mostly mild to moderate. Severe peripheral edema and pleural effusions were not observed. The most common grade 3 or higher hematologic adverse events were thrombocytopenia (35%) and neutropenia (21%). Grade 3 or higher bilirubin and lipase elevations occurred in 9% and 18% of patients, respectively, resulting in treatment discontinuation in one patient. In conclusion, nilotinib is an effective and well-tolerated treatment in imatinib-resistant and -intolerant CML-AP. This trial is registered at www.clinicaltrials.gov as NCT00384228.

Long‐term experience with imatinib therapy in chronic phase chronic myelogenous leukemia—Remarkable activity with room for improvement

Long‐term experience with imatinib therapy in chronic phase chronic myelogenous leukemia—Remarkable activity with room for improvement

Hepatic Response after High-Dose Melphalan and Stem Cell Transplantation for AL Amyloidosis Associated Liver Disease.

Immunoglobulin light chain (AL) amyloidosis is a plasma cell dyscrasia with extracellular protein deposition in various organ systems, including the liver. The natural history of AL amyloidosis with liver involvement has a poor prognosis, with median survival of only 8.5 to 9 months. High-dose melphalan chemotherapy and autologous peripheral blood stem cell transplantation (HDM/SCT) has been shown to result in durable hematologic response and prolonged overall survival in systemic AL amyloidosis. Patients were included who had hepatic involvement and received HDM/SCT from 1998 to 2006. Data was collected with the approval of the Institutional Review Board. Patients receiving HDM/SCT had to meet eligibility criteria to qualify for this aggressive treatment. Stem cells were mobilized using G-CSF alone. Intravenous melphalan was administered at 100–200 mg/m2 over 2 days in divided doses and stem cells were re-infused 24–72 hours after HDM. Liver response was determined by criteria set up by the Consensus Opinion from the 10th International Symposium on Amyloid and Amyloidosis. Sixty-nine patients qualified for this study, including 47 males and 22 females. The median age was 56 years (range, 37–75), median bilirubin was 0.5 mg/dL (range, 0.1 to 5.7), median alkaline phosphatase was 193 U/L (range, 59 to 1243) and the median liver size was 3 cm (range, 0–20cm) below the costal margin. Nine patients (13%) died from treatment-related mortality. The hematologic CR one year after treatment was achieved by 53% (31/58) of evaluable patients. The overall survival was 84% at 1 year and 49% at 5 years, by Kaplan-Meier estimates. Hepatic response occurred in 21% (10/47) at 1 year after HDM/SCT and 40% (12/30) at 2 years after HDM/SCT. In summary, hepatic involvement with AL amyloidosis does not increase treatment-related mortality from HDM/SCT. Hepatic response follows a hematological response and can occur as far as 2 years from HDM/SCT. Forty % of surviving evaluable patients showed remission of their hepatic disease from AL amyloidosis by 2 years.

Immune Effects of Imatinib in Chronic Myelogenous Leukemia In Vitro.

Imatinib mesylate, a potent and selective inhibitor of the BCR-ABL tyrosine kinase, has been shown to induce durable haematological and major cytogenetic responses in a high percentage of CML patients. However in most patients the disease recurs, when imatinib is discontinued. In contrast, allogeneic stem cell transplantation (ASCT) is considered to be curative by the immune effect of donor T cells against CML progenitor cells. In this context, the role of imatinib is controversial; it may improve the results of ASCT by reducing the tumour load, it may also reduce the effect of donor lymphocyte transfusions (DLT) by impairing the function of T cells and the capacity of myeloid cells to present antigen. Patient derived CML-cells were studied for the stimulation of allogeneic HLA-matched and mismatched T-cells in the presence and absence of imatinib. In a 5 day culture the proliferative response of HLA-mismatched T cells was evaluated in presence of different concentrations of imatinib (0, 1, 2, or 5 micro M) and various responder-to-stimulator ratios. Thereby, proliferation was detected via a CFDA based assays and the activation profile (CD25, CD69) of the T-cells was determined by FACS. Cr51-release assays were performed after a 7 day culture of CML cells with HLA-matched T cells to test cytotoxicity of CD8+ T-cells. In addition, we characterized the antigen-presenting profile (CD14, CD33, HLA-DR, CD40, CD80, CD86, CD54, CD58) of the CML cells over a 5 day culture with and without imatinib. The presence of imatinib inhibited the proliferative capacity of allogeneic T-cells in a dose-dependent manner. Also, the expression of T cell activation markers was reduced in the presence of the different imatinib concentrations. Preincubation of CML cells with imatinib for 48 hours strengthened the effect on proliferation and activation of T cells. Moreover, imatinib impaired the cytotoxic function of T-cell (HLA-matched setting; CR51-release assay) also in a dose-dependent manner. Finally, the antigen-presenting profile of the myeloid leukemia cells was down regulated by increasing concentrations of imatinib. In summary, imatinib may interfere with the T cellular immune response and the antigen presenting profile on the CML cells in vitro. These results may have an impact on new strategies of treatment of CML with immunotherapy.

Rituximab responsive immune thrombocytopenic purpura in an adult with underlying autoimmune lymphoproliferative syndrome due to a splice‐site mutation (IVS7+2 T&gt;C) affecting the Fas gene

A 36 yr-old man of Israeli descent with a history of childhood splenectomy for severe thrombocytopenia and a family history of autoimmune lymphoproliferative syndrome (ALPS), presented with severe immune thrombocytopenic purpura refractory to standard therapy. He was found to possess a heterozygous mutation in the Fas gene (also termed TNFRSF6, CD95, Apo-1) affecting the donor splice site of intron 7 (IVS7+2 T>C). This frameshift mutation truncates the cytoplasmic domain of the Fas death receptor, resulting in circulating CD4/8 double negative T lymphocytes, lymphadenopathy and autoimmune complications typical of ALPS. Administration of Rituximab in this patient was associated with a durable hematologic response (currently more than 12 months). This report highlights the need to consider rare inherited causes of thrombocytopenia in adults with a family history of immune cytopenia(s) and the effective use of anti-CD20 monoclonal antibody in patients unresponsive to immunosuppression and splenectomy.

Dasatinib phase I/II study of patients with chronic myeloid leukemia (CML) resistant or intolerant to imatinib: Results of the CA180031 study in Japan

17515 Background: Dasatinib is a potent, orally active, multi-targeted kinase inhibitor of BCR-ABL and SRC family kinases. Studies outside Japan have shown dasatinib to be highly effective in overcoming resistance and intolerance to imatinib, inducing durable cytogenetic (CyR) and hematologic responses (HR) in this population. The maximum tolerated dose was not reached in the Phase-I trial outside Japan and a 70-mg BID dose was determined to provide the optimal benefit-risk profile. Methods: This Phase-I/-II study was designed to assess the safety and efficacy of dasatinib in Japanese patients with imatinib-resistant or -intolerant CML or Ph+ALL. In the 4-week Phase-I portion in patients with chronic-phase (CP) CML, three dose levels were evaluated: 50 mg, 70 mg, and 90 mg BID. The Phase-II portion is currently evaluating the CyR of dasatinib in patients with CP-CML at 24 weeks, and the HR rate in accelerated- (AP) or blast-phase (BP) CML and Ph+ ALL at 12 weeks. Results: As of December 2006, 17 eligible patients have been treated in Phase I. Six patients (4F, 2M; median age 43 y [range 27–56]) were treated with 50 mg BID and 1 dose-limiting toxicity (DLT) was observed (Grade 4 thrombocytopenia). Two patients experienced transient Grade 3 ALT elevations but as treatment was uninterrupted, these were not considered DLTs. Six patients (6M; median age 42 y [range 27–55]) were treated with 70 mg BID and again 1 DLT was observed (Grade 4 thrombocytopenia). No DLT has been observed among 4 patients (3M, 1F; median age 41 y [range 27–64]) at the 90-mg BID dose. Major CyRs have been achieved in all three cohorts in the Phase-I segment of the trial. Thirty six patients were enrolled and treated in the Phase-II part of the trial (12 CP-CML, 7 AP- CML, 4 BP-CML, and 13 Ph+ALL). Efficacy and safety data as well as the baseline BCR-ABL mutation data are currently being assessed and will be presented. Conclusions: Dasatinib can be safely administered at doses of up to 90 mg BID to Japanese patients with imatinib-resistant or -intolerant CP-CML. No significant financial relationships to disclose.

A phase II study of nilotinib administered to imatinib resistant or intolerant patients with chronic myelogenous leukemia (CML) in accelerated phase (AP)

7026 Background: CML-AP is often associated with imatinib-resistance and the occurrence of BCR-ABL mutations. This phase II open-label study was designed to evaluate the safety and efficacy of Nilotinib, a potent novel tyrosine kinase inhibitor, in imatinib-resistant or - intolerant CML-AP pts. Methods: Imatinib-resistance and -intolerance were defined using standard criteria, and all resistant pts failed imatinib &gt;/= 600mg/day. Primary endpoint was a confirmed hematologic response (HR) determined by conventional ITT analysis. Nilotinib was started at 400mg BID and escalated to 600mg BID for inadequate responses. Results: Safety and efficacy are reported for first 64 consecutively enrolled pts completing &gt;/= 8 mos treatment. 52 (81%) were imatinib-resistant; 12 (19%) -intolerant. Median duration of CML was 74 mos; median duration of prior imatinib use was 28 mos. Median duration of nilotinib exposure was 208 days; median average dose intensity (mg/days) was 787. Median cumulative duration of dose interruption was 23 days. Treatment is ongoing for 27 (42%) pts; 37 (58%) have discontinued (9 for AEs; 17 for disease progression). HR occurred in 38 (59%) pts, of which 15 (23%) were complete, 8 (13%) were marrow responses, and 15 (23%) returned to chronic phase. MCyR occurred in 23 (36%) pts; 14 (22%) were complete and 9 (14%) were partial. 6 (9%) pts did not respond; 5 (8%) pts had disease progression. Median time to HR was 1.0 (1–3) mos and to MCyR was 2.0 (1–8) mos. Estimated 1-yr survival rate was 69% and median duration of HR has not been reached. The most common Grade 3/4 AEs included neutropenia (45%), thrombocytopenia (40%), asymptomatic lipase elevations (17%), and anemia (16%) pts. No pts experienced Grade 3/4 peripheral edema, or pleural/pericardial effusions; 2 pts had pulmonary edema. Conclusion: In pts with CML-AP, nilotinib is an effective therapeutic option in CML-AP pts with imatinib-resistance or -intolerance and is generally well tolerated with acceptable rates of myelosuppression and minimal non- hematologic toxicities. No significant financial relationships to disclose.

The novel tyrosine kinase inhibitor EXEL-0862 induces apoptosis in human FIP1L1-PDGFR-α-expressing cells through caspase-3-mediated cleavage of Mcl-1

The FIP1-like-1 (FIP1L1)-platelet-derived growth factor receptor-alpha (FIP1L1-PDGFR-alpha) fusion kinase causes hypereosinophilic syndrome (HES) in a defined subset of patients. Imatinib mesylate is a potent inhibitor of ABL but also of PDGFR-alpha, and has been associated with durable hematologic responses in patients with HES. However, development of mutations in the tyrosine kinase domain may hamper the activity of tyrosine kinase inhibitors (TKIs), which suggests that novel agents are warranted to prevent or overcome resistance. We evaluated the efficacy of the novel TKI EXEL-0862 in FIP1L1-PDGFR-alpha-expressing cell lines and in cells from a patient with HES harboring the FIP1L1-PDGFR-alpha gene. EXEL-0862 inhibited the proliferation of EOL-1 and imatinib-resistant T674I FIP1L1-PDGFR-alpha-expressing cells and resulted in potent inhibition of the phosphorylation of PDGFR-alpha and downstream proteins STAT3 and Erk1/2, both in vitro and ex vivo. Moreover, EXEL-0862 induced apoptotic death in EOL-1 cells and imatinib-resistant T674I FIP1L1-PDGFR-alpha-expressing cells, and resulted in significant downregulation of the antiapoptotic protein Mcl-1 through a caspase-dependent mechanism. Our data establish EXEL-0862 as a solid candidate for the targeted treatment of patients with FIP1L1-PDGFR-alpha-positive HES.

Successful treatment of AL amyloidosis with high-dose melphalan and autologous stem cell transplantation in patients over age 65

AbstractRecently, protocols using high-dose melphalan chemotherapy and autologous peripheral blood stem cell transplantation (HDM/SCT) have been developed for the treatment of patients with immunoglobulin light chain (AL) amyloidosis. Although peritransplantation mortality is greater than for other hematologic diseases, treatment leads to durable hematologic complete responses, improvements in organ function and quality of life, and extended survival in a substantial proportion of patients. To determine whether this treatment can be applied to older patients, we have analyzed HDM/SCT treatment outcomes for 65 patients (aged 65 years or older) with AL amyloidosis compared with outcomes for 280 younger patients. For patients over age 65 years who meet the same eligibility criteria as younger patients, toxicity, hematologic remission rate, and survival were not significantly different from those observed in younger patients, indicating that older patients should not be excluded a priori from consideration for HDM/SCT treatment.

The Novel Tyrosine Kinase Inhibitor (TKI) Exel-0862 Potently Induces Apoptosis in Human FIP1L1-PDGFR-α-Expressing Cells through Caspase-Dependent Cleavage of MCL-1.

The FIP1L1-PDGFR-α fusion kinase induces hypereosinophilic syndrome (HES) in a subset of patients (pts). Imatinib is a potent inhibitor of PDGFR-α and has been associated with durable hematologic responses in pts with HES. However, development of kinase domain mutations may hamper TKI activity, underscoring the need for novel agents to prevent or overcome resistance. We evaluated the efficacy of the novel TKI EXEL-0862 in FIP1L1-PDGFR-α-expressing cells. In 72-hour MTS assay, EXEL-0862 inhibited EOL-1 cell proliferation with an IC50 of 1.0 nM and markedly decreased phosphorylation of STAT3 and Erk1/2, suggesting inhibition of downstream targets of PDGFR-α. More important, EXEL-0862 induced dose-dependent inhibition of PDGFR-α phosphorylation in peripheral blood mononuclear cells from a pt with HES. Exposure of EOL-1 cells to EXEL-0862 10 nM for 24 hours caused apoptosis as evidenced by flow cytometry (annexin-V/PI staining) and transmission electron microscopy. This was coupled with time-dependent cleavage of caspases-3, caspase-9, and PARP and with mitochondrial damage as reflected by cytochrome c translocation into the cytosol, and a diminished mitochondrial transmembrane potential. Of note, apoptotic features were not evident after 16 hours of EXEL-0862 exposure. Immunoblots showed marked downregulation of Mcl-1, but not of Bcl-2, Bcl-XL, or Bax. To elucidate the mechanism of Mcl-1 cleavage, EOL-1 cells were exposed to 10 nM EXEL-0862 for 6 hours followed by cycloheximide (5 μg/ml), a potent translation inhibitor, which resulted in marked Mcl-1 turnover. Treatment with the proteasome inhibitor MG-132 failed to abrogate EXEL-0862-induced Mcl-1 cleavage, suggesting proteasome-independent degradation. Rather, a decrease of pro-form Mcl-1 (p42) and increase of the cleaved Mcl-1 peptide form of Mcl-1 (p28) coincided with caspase-3 activation. Pretreatment with 20 μM pan-caspase inhibitor Z-VAD abolished EXEL-0862-induced Mcl-1 cleavage, pointing to a caspase–dependent mechanism. Collectively, our results establish EXEL-0862 as a solid candidate for the targeted treatment of pts with FIP1L1-PDGFR-α-positive HES.

European Multi-Centre Study on the Use of Anti-Thymocyte Globulin in the Treatment of Myelodysplastic Syndromes.

In patients with myelodysplastic syndromes (MDS), there is increasing evidence to suggest that immunological dysregulation plays an important role contributing to ineffective haematopoiesis and progressive cytopenias. Several studies have suggested that a sub-group of patients with low-risk MDS may respond to treatment with anti-thymocyte globulin (ATG). The characteristics of this group are still being defined.We reviewed the outcomes of 68 patients with MDS treated with ATG in the United Kingdom and Italy. All patients received a single treatment course of lymphoglobuline (Sangstat-Genzyme) (1.5 vials/10 kg/day for 5 days;1 vial contains 100mg protein). The study end-point was response at 6 months. Haematological response was assessed as per the Cheson criteria. The median age of the patients was 51.5 years (range: 19–75). There were 40 (59%) male and 28 (41%) female patients. The diagnosis as defined by FAB classification was refractory anaemia (RA) n=53, refractory anaemia with ring sideroblasts (RARS) n=4, and refractory anaemia with excess blasts (RAEB) n=11. IPSS was low n=3, Int-1 n=53, Int-2 n=5, high n=4. 19/54 patients had a normocellular/hypercellular bone marrow, 35/54 patients had a hypocellular bone marrow. Cytogenetic risk as defined by IPSS was low n=50, intermediate n=8, high n=6. HLA-DR15 was available in 27 patients, of which 10 were positive. Only 1 of 23 patients tested for the presence of PNH clone was positive. 61/68 patients were blood transfusion dependent and 31/68 were platelet transfusion dependent at time of treatment. The median duration from diagnosis to treatment with ATG was 13 months (range: 0.5–342).30/68 (43%) patients had a partial or complete response to ATG. The median age of responders was 49.5 years (range: 19–73). At 6 months assessment, 26/30 patients had a erythroid response (20 major, 6 minor), 10/30 patients had a neutrophil response (8 major, 2 minor) and 20/30 patients had a platelet response (12 major, 8 minor). The median duration of response was 29 months (range: 2–83). 6/30 (20%) patients (3 RAEB, 3 RA) relapsed after initial response to ATG with 3 patients progressing to AML (2 RAEB, 1 RA). There was no significant difference in age, time from diagnosis to treatment, bone marrow cellularity, FAB classificiation, cytogenetic risk or HLA-DR15 status between responders and non-responders. However, responders to ATG had a more favourable IPSS (Low, Int-1 as compared to Int-2, High) (p=0.03). The 3 year actuarial overall survival between responders and non-responders is 87% vs 40% (p=0.01). On univariate analysis, response to ATG, IPSS, and FAB classification were strongly associated with overall survival, however on multivariate analysis, IPSS was the only independent variable for overall survival (p<0.01 HR 3.46 95%CI 2.01–5.94).A single course of ATG can induce durable haematological responses in a significant proportion of patients with MDS, with improved overall survival. ATG should be considered as a treatment option in patients with low IPSS.

Successful Treatment of AL Amyloidosis Patients over Age 65 with High-Dose Melphalan and Autologous Stem Cell Transplantation (HDM/SCT).

Over the past 10 years, HDM/SCT has been employed for treatment of patients with AL amyloidosis. Although peri-transplant mortality is greater than for other hematologic diseases, HDM/SCT leads to durable hematologic complete responses (CR), improvements in organ function, and extended survival in a substantial proportion of patients (Skinner et al., Ann. Int. Med. 2004). In that study, the proportion of patients eligible for HDM/SCT was lower for patients >65 years of age than for younger patients (34.3% vs. 68.4%), but the hematologic complete response (CR) rate and survival appeared to be no different. Here, we update these results and present a detailed analysis of outcomes in patients >65 vs. those <65. Data were collected with IRB approval. Through 07/01/04, 349 patients began G-CSF mobilization, of which 66 (19%) were >65. The median age of the 66 patients was 68, range 65–80; 73% male; 18% ? and 82% ?, while for the 283 patients <65, the median age was 55, range 29–64; 57% male; 16% ? and 84% ?. The median number of involved organs was no different in the two groups, nor was the type of organ involvement or performance status. There was also no difference in the rate of serious complications during stem cell collection, as a similar fraction of patients in both groups did not proceed to transplant, 12.1% of patients >65 versus 10.3% of patients <65 (p=.659). Based on treatment protocol, only 19% of patients >65 received an IV dose of melphalan of 200 mg/m2 (the remainder being treated with 140 mg/m2 or less), vs. 64% of those <65 (p <.001). There was no difference in early transplant-related mortality (10.3% in patients >65 vs. 13.4% in patients <65, p=.665). There was also no difference in one year mortality (22.4% for those >65 vs. 20.9% for those <65, p=.859). There was a non-significant trend towards a lower rate of hematologic CR in the older patients (32% vs. 44%, p=0.155). However, the median survival after HDM/SCT was no different (see fig; 4.9 years for patients >65 vs. 4.6 years for those <65, p=0.42 by log-rank test). Thus, while fewer patients >65 meet eligibility requirements for HDM/SCT, for those who do, treatment-related mortality, hematologic CR rate, and survival are no different than for younger patients. These data strongly support the use of HDM/SCT for suitable patients with AL amyloidosis who are >65 years old. [Display omitted]

PKC412 overcomes resistance to imatinib in a murine model of FIP1L1-PDGFRα-induced myeloproliferative disease

FIP1L1-PDGFRα causes hypereosinophilic syndrome (HES) and is inhibited by the tyrosine kinase inhibitor imatinib (Gleevec). Imatinib is a potent inhibitor of ABL, ARG, PDGFRα, PDGFRβ, and KIT and induces durable hematologic responses in HES patients. However, we observed relapse with resistance to imatinib as consequence of a T674I mutation in FIP1L1-PDGFRα, analogous to the imatinib-resistant T315I mutation in BCR-ABL. We developed a murine bone marrow transplant model of FIP1L1-PDGFRα-induced myeloproliferative disease to evaluate the efficacy of PKC412, an alternative inhibitor of PDGFRα, for the treatment of HES. PKC412 is effective for treatment of FIP1L1-PDGFRα-induced disease and of imatinib-induced resistance due to the T674I mutation. Our data establish PKC412 as molecularly targeted therapy for HES and other diseases expressing activated PDGFRα and demonstrate the potential of alternative kinase inhibitors to overcome resistance in target tyrosine kinases.

Effects of imatinib on bone marrow engraftment in syngeneic mice.

Chronic myeloid leukemia (CML) and a subset of acute lymphoblastic leukemias arise from the genetic reciprocal translocation t(9;22), forming the BCR-ABL fusion gene. These lead to the expression of the constitutively active tyrosine kinase BCR-ABL, which is the causative oncogene for these leukemias. Allogeneic bone marrow transplantation (BMT) or stem cell transplantation (SCT) is currently considered the only curative treatment for chronic myeloid leukemia (CML). Recently, the selective tyrosine kinase inhibitor imatinib mesylate (Glivec, formerly STI-571) has been shown to induce durable hematologic and major cytogenetic responses in a high percentage of patients with chronic phase CML. In patients with advanced disease remissions are transient and most patients relapse despite continued imatinib treatment. Some of these patients go on to receive allogeneic BMT or SCT, during which administration of imatinib is usually discontinued as it is believed to interfere with bone marrow engraftment. In this study, we examined the effect of imatinib on hematopoietic engraftment in a syngeneic mouse model. We found that imatinib has no significant influence on hematopoietic recovery in lethally irradiated mice in vivo. Thus, our results suggest that continued administration of imatinib in the course of BMT or SCT may be a feasible therapeutic regimen.