[1989] The SRC/ABL Inhibitor BMS-354825 Overcomes Resistance to Imatinib Mesylate in Chronic Myelogenous Leukemia Cells through Multiple Mechanisms. Session Type: Poster Session 202-II

Nicholas J. Donato, Ji Wu, Ling Y. Kong, Francis Lee, Moshe Talpaz. Bioimmunotherapy, M.D. Anderson Cancer Center, Houston, TX, USA; Cancer Therapeutics, Bristol-Myers Squibb, Princeton, NJ, USA

BCR-ABL is an oncogenic tyrosine kinase expressed in chronic myelogenous leukemia (CML) cells and is the main target of the tyrosine kinase inhibitor imatinib mesylate. Imatinib-based CML therapy induces hematological and cytogenetic remission in early phase CML patients whereas more advanced patients frequently develop resistance to imatinib by multiple mechanisms, including mutations in the BCR-ABL kinase domain and over-expression of tyrosine kinases that are not inhibited by imatinib. These observations suggest that dual inhibition of src and abl kinases may circumvent imatinib resistance and provide more effective therapy for CML. BMS-354825 is a novel tyrosine kinase inhibitor that inhibits both abl and src kinases at low nM concentrations and is currently being clinically evaluated in imatinib resistant or intolerant CML patients. Our earlier studies demonstrated that increased expression of the src-related kinase Lyn in BCR-ABL expressing K562 cells was associated with imatinib resistance in this cell model and some CML patients. To determine whether inhibition of SRC/ABL kinases differentially affects imatinib sensitive K562 (BCR-ABL +, Lyn -) and resistant K562R (BCR-ABL +, Lyn +) cells were treated with imatinib or BMS-354825 before analysis of cell growth, survival and signaling. BMS-354825 induced apoptosis in both K562 and K562R cells which correlated with inhibition of both Lyn activation and BCR-ABL signaling (CrkL). BMS-354825 effectively reduced both K562 and K562R tumor growth in nude mice whereas imatinib had minimal effects on K562R tumors. Clinical specimens from imatinib resistant CML patients (with and without BCR-ABL kinase mutations) were treated with imatinib or BMS-354825 and analyzed for changes in Lyn and Hck activation. While imatinib had minimal inhibitory effects on Lyn/Hck activation, BMS-354825 completely suppressed Lyn/Hck phosphorylation which correlated with its greater anti-tumor activity in CML samples. BCR-ABL tyrosine phosphorylation was not inhibited by imatinib in Cos cells co-expressing BCR-ABL and Lyn kinase and loss of imatinib sensitivity was totally dependent on Lyn kinase activity. BMS-354825 reduced both Lyn and BCR-ABL activation in co-expressing cells, suggesting that Lyn-mediated phosphorylation plays a direct role in imatinib resistance. We conclude that dual inhibition of SRC/ABL kinases in CML cells by BMS-354825 overcomes resistance to imatinib in vitro and in vivo and induces anti-tumor effects in CML patient specimens resistant to imatinib through expression of imatinib-inactivating BCR-ABL kinase mutations as well as other resistance mechanisms. Abstract #1989 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: Chronic myeloid leukemia|Imatinib resistance|Tyrosine kinase inhibitor

Sunday, December 5, 2004, 06:00 PM

Poster Session: CML - Targeted Therapy (6:00 PM-7:30 PM)

[276] Molecular Remission to Imatinib in Patients with Chronic Myeloid Leukaemia (CML) Is Less Durable Compared to Patients after Allografting. Session Type: Oral Session

Thoralf Lange, Thomas Bumm, Marc Mueller, Sandra Otto, Haifa K. Al-Ali, Leanthe Grommisch, Scarlet Musiol, Christina Franke, Rainer Krahl, Dietger W. Niederwieser, Michael W. Deininger. Dept.of Hematology and Oncology, University of Leipzig, Leipzig, Germany; Dept.of Clinical Chemistry and Molecular Diagnostics, University of Leipzig, Leipzig, Germany; Center for Hematologic Malignancies, Oregon Health and Science University, Portland, OR, USA

Objectives: Patients with CML who achieve molecular remission (MR, defined as a RT-PCR negativity for BCR-ABL transcripts) after myeloablative stem cell transplantation (SCT) have a low risk of relapse, and the majority may be cured. The frequency of MR on imatinib varies greatly and the durability of these responses has not been reported. To investigate if MR after SCT and on imatinib are equally stable, we directly compared two cohorts of patients treated with imatinib or SCT, respectively, from the time of their first negative RT-PCR result. Patients and Methods: One hundred and forty-four CML patients in chronic (n=104) or accelerated phase (n=40) treated with standard dose imatinib were routinely monitored by conventional cytogenetics, quantitative RT-PCR (qPCR) and conventional nested PCR in case of negative qPCR results. Nineteen patients (13.2%) had at least 1 negative nested PCR. To assess the level of residual disease in patients with a single negative RT-PCR result, 10 replicate reactions were performed, each corresponding to > 106 white bone marrow cells. Thirty-six samples (median 3, range 1-4) from patients in MR on imatinib and 45 samples (median 2, range 1-3) from patients in MR after SCT were available. Twenty samples from healthy individuals were tested as controls.

Results: The first negative result was noted after a median of 16.8 months (range 11.5-36.1) of imatinib therapy and 6.6 months (range 4.7-9.5) after SCT, respectively. The projected risk of molecular relapse at 12 months after the first negative RT-PCR result was 83% in patients on imatinib but only 20% in patients after SCT (P = 0.0001). Only two patients on imatinib remained in molecular remission at 13.8 and 16.6 months. While none of the patients with molecular relapse after allograft lost CCyR, one patient on imatinib progressed to cytogenetic relapse. The replicate assay was positive in 18/36 samples (50%) from patients on imatinib, 8/46 (17.4%) after allografting and 4/20 (20%) from healthy individuals. These differences were significant between patients on imatinib and after allografting (P = 0.003) and between patients on imatinib and healthy individuals (P = 0.005), but not between patients after allografting and healthy individuals (P = 0.9). Negativity by replicate testing was more stable in patients after allografting, although, even in these patients, positive replicate reactions continued to occur with longer follow-up.

Conclusion: Imatinib-induced MR is usually not durable, in contrast to MR after transplant. Consistent with this, the level of residual disease in samples negative by single nested PCR is higher in patients on imatinib compared to patients after SCT. These results suggest that disease eradication with imatinib monotherapy may be rare. Patients on imatinib followed by PCR should be made aware of the fact that a single negative test does not have the same significance as in patients after SCT.

Abstract #276 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: Chronic myeloid leukemia|Imatinib|Allograft

Monday, December 6, 2004, 12:15 PM

Simultaneous Session: CML - Molecular Monitoring of Residual Disease and Bcr-Abl Kinase Mutation (11:00 AM-12:30 PM)

[1098] BCR-ABL RNA Levels at the Time of a Complete Cytogenetic Response (CCR) Predict the Duration of CCR in Imatinib-Treated Chronic Myeloid Leukemia Patients. Session Type: Poster Session 252-I

Richard D. Press, Zac Love, Ashlie A. Tronnes, Gwen Kurilik, Michael J. Mauro, Michael W. Deininger, Brian J. Druker. Pathology, Oregon Health & Science University, Portland, OR, USA; Leukemia Center, Oregon Health & Science University, Portland, OR, USA

Background : Imatinib induces a complete cytogenetic response (CCR) in the majority of patients with chronic phase CML. CCR is durable in the majority of patients, but relapse occurs in a subset. To determine the potential of quantitative RT-PCR (qPCR) of BCR-ABL to predict cytogenetic relapse, we serially monitored residual disease in 90 CML patients with an imatinib-induced CCR.

Methods and patients : mRNA was prepared from total nucleated cells from blood or bone marrow, and cDNA was synthesized using random hexamer primers. Relative BCR-ABL expression was then measured by real-time fluorescent PCR normalized for G6PDH expression. This assay has a detection limit of 1 CML cell in 100,000 and an analytical precision of 6% (CV). At the start of imatinib therapy, 85% of patients were in chronic phase, at a median 9.5 months after diagnosis. Patients were treated with imatinib alone (64%) or in combination with interferon or cytarabine (32%). One patient each was treated with imatinib in combination with either the farnesyltransferase inhibitor tipifarnib, donor leukocytes (after allogeneic BMT), or an experimental heat shock protein (hsp70) vaccine. During the imatinib follow-up time of 28 months (median), disease monitoring occurred by cytogenetics and qPCR (median 6 samples per patient). The CCR was achieved after 9.7 months (median) of imatinib therapy.

Results : At the time of first achieving CCR, BCR-ABL RNA levels had decreased by a median of 1.8 logs below the median baseline level. During further follow-up, 26 patients (29%) experienced cytogenetic relapse (defined as any Ph-positive metaphase cell) at a median 6.0 months after CCR and a median 20 months after starting imatinib. There was no difference in the imatinib treatment time, the time to achieve CCR, or the post-CCR follow-up period between the patients with and without subsequent cytogenetic progression. qPCR data at the time of first CCR were available for 78 patients, including 25 of 26 with a subsequent cytogenetic relapse. The reduction of BCR-ABL RNA at the time of first achieving CCR was significantly less in those patients with a subsequent cytogenetic relapse (median 1.4 log) compared to those with a sustained CCR (median 2.0 log) (P=0.002). In the 64 patients with a sustained CCR, the molecular response progressively improved over time to reach a median reduction of 4.0 log at 15 months after CCR. Of the 29 patients achieving at least a 2 log reduction of BCR-ABL RNA at the time of first reaching CCR, only 3 (10%) had a subsequent cytogenetic relapse. In comparison, 22 of 49 patients (45%) with a less than 2 log reduction at the time of achieving CCR had a subsequent cytogenetic relapse (odds ratio = 7.1; 95% CI 1.9-26). At the time of first achieving CCR, a reduction in BCR-ABL RNA of less than 2 logs thus had a diagnostic sensitivity of 88% and a diagnostic specificity of 49% for predicting subsequent cytogenetic relapse.

Conclusions : We conclude that, in the majority of imatinib-treated CML patients reaching CCR, the level of BCR-ABL RNA at the time that the CCR is first achieved is a sensitive predictor of the durability of the CCR. The availability of a laboratory marker capable of stratifying the subsequent risk of disease progression (early in remission) will be useful in targeting additional (or alternative) therapies to those patients with the highest risk.

Abstract #1098 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: Prognostic factor|Molecular markers|Quantitative RT-PCR

Saturday, December 4, 2004, 06:00 PM

Poster Session: Diagnostic and Prognostic Markers in Leukemia I (6:00 PM-7:30 PM)

[1983] AMN107, a Novel Aminopyrimidine Inhibitor of BCR-ABL, Has Pre-Clinical Activity Against Imatinib Mesylate-Resistant Chronic Myeloid Leukemia (CML). Session Type: Poster Session 196-II

Mirna Golemovic, Francis J. Giles, Miloslav Beran, Jorge Cortes, Taghi Manshouri, Hagop Kantarjian, Srdan Verstovsek. Leukemia, UT MD Anderson Cancer Center, Houston, TX, USA

Resistance to, or intolerance of, imatinib mesylate in patients with CML has encouraged the development of other Bcr-Abl inhibitors. AMN107 is a novel oral aminopyrimidine ATP-competitive inhibitor of the protein tyrosine kinase activity of Bcr-Abl. Following oral administration to animals, AMN107 is well absorbed, has a good pharmacokinetic profile, and is well tolerated. The activity of AMN107, relative to imatinib, in both imatinib sensitive (KBM5 and KBM7) and corresponding imatinib-resistant (KBM5-STI571R1.0 and KBM7-STI571R1.0) cell lines was studied. KBM5 cells contain multiple copies of the Ph chromosome but lack the normal c-ABL. KBM7 cell line is near haploid. KBM5 and KBM7 cells differ in their response to imatinib exposure: no apoptosis with G0/G1 cell cycle arrest in KBM5 cells in contrast to apoptosis in KBM7 cells. KBM5-STI571R1.0 and KBM7-STI571R1.0 have an imatinib IC50 (concentration that kills 50% of the cells) about twenty times higher then the value in the corresponding parental cell line. KBM5- STI571R1.0 have a marginal increase in the BCR-ABL gene copy number, modest increase in p210 protein expression, but a highly imatinib-resistant Bcr/Abl tyrosine kinase activity associated with the acquisition of a single C-T change at ABL nucleotide 944 (T315I). KBM7-STI571R1.0 cells have no mutations within the ATP-binding domain of the Bcr/Abl, but have amplification of BCR/ABL gene and increased levels of expression of Bcr/Abl p210 protein, with decreased inhibition of the Bcr/Abl tyrosine kinase activity by imatinib, and loss of apoptotic response to imatinib. AMN107 showed higher potency in KBM5 cells than imatinib in suppressing cell growth (MTS assay) with IC50 values of 11.3 nM and 480.5 nM respectively. With KBM5-STI571R1.0, IC50 were 2418.3 nM and 6361.4 nM for AMN107 and imatinib, respectively. The IC50 for AMN107 and imatinib treatment in KBM7 cell line were 4.3 nM and 259.0 nM, respectively. In KBM7-STI571R1.0 IC50 were 97.2 nM and 2497.3 nM for AMN107 and imatinib, respectively. In experiments focused on cell cycle analysis and caspase-3 activity, the cell cycle distribution and apoptotic responses induced by imatinib and AMN107 appeared generally similar in all four ell lines, but at significantly lower concentrations of AMN107 (corresponding to findings in MTS assay). At a concentration of 2.5 mM, imatinib inhibited completely Bcr-Abl phosphorylation in both KBM5 and KBM7 cells, while AMN107 achieved the same effect at 125.0 nM In imatinib-resistant cells imatinib did not completely inhibit Bcr-Abl phosphorylation even when doses as high as 10.0 mM were applied, while AMN107 inhibited Bcr-Abl phosphorylation at 2.5 mM. The survival of SCID mice bearing KBM5 cells treated with AMN107 was significantly extended when compared with controls. Irradiated female five weeks old SCID mice were injected intraperitonealy (ip) with 2.4 x 107 KBM5 cells on Day 0. Treatment with AMN107 started on Day 20 and was given daily ip for 20 days. T/C survival ratios were 144%, 159%, and 182% for groups treated with 10, 20, and 30 mg/kg, respectively. AMN107 has significant activity against imatinib-sensitive and -resistant CML and warrants investigation in patients with CML.

Abstract #1983 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: Kinase inhibitor|Philadelphia chromosome|Imatinib resistance

Sunday, December 5, 2004, 06:00 PM

Poster Session: CML - Targeted Therapy (6:00 PM-7:30 PM)

[1] Hematologic and Cytogenetic Responses in Imatinib-Resistant Chronic Phase Chronic Myeloid Leukemia Patients Treated with the Dual SRC/ABL Kinase Inhibitor BMS-354825: Results from a Phase I Dose Escalation Study. Session Type: Plenary Session

Charles L. Sawyers, Neil P. Shah, Hagop M. Kantarjian, Nicholas Donato, John Nicoll, Stephen A. Bai, Fei Huang, Edwin Clark, Arthur P. DeCillis, Moshe Talpaz. Hematology-Oncology, David Geffen School of Medicine at UCLA/Howard Hughes Medical Institute, Los Angeles, CA, USA; Department of Leukemia, MD Anderson Cancer Center, Houston, TX, USA; Bristol-Myers Squibb, Princeton, NJ, USA; Equal Contribution

Disease relapse in CML patients treated with imatinib is often associated with mutations in the BCR-ABL gene that interfere with the ability of imatinib to block BCR-ABL kinase activity. BMS-354825 is a novel, orally available, dual SRC/ABL kinase inhibitor with more than 100-fold greater potency than imatinib that has in vitro and in vivo preclinical activity against 14 of 15 imatinib resistant BCR-ABL mutants (Shah et al, Science, 305:399, 2004). Here we report the phase I clinical results of BMS-354825 in Philadelphia chromosome positive (Ph+) CML patients in chronic phase with hematologic progression or intolerance while being treated with imatinib. To date (Aug 6, 2004), 29 patients have been treated on 9 cohorts with doses ranging from 15 to 180 mg of BMS-354825 per day given in single or divided doses for 5-7 days per week, for up to 9 months. Similar to imatinib, BMS-354825 has been well tolerated in all patients, with a single episode of grade 4 thrombocytopenia as the only potential drug related adverse event. BMS-354825 is rapidly absorbed with peak concentrations achieved within 2 hours and a terminal phase half-life of about 5 hours. Serum levels well above the concentration required to block CML cell proliferation in vitro have been readily achieved without side effects.

Pharmacodynamic studies demonstrate greater than 50 percent inhibition of phosphorylation of the BCR-ABL substrate CRKL and the SRC kinase Lyn, consistent with the serum concentrations observed in pharmacokinetic studies. Patients not receiving optimal clinical benefit were escalated to the next higher dose for which safety parameters were available, thereby allowing a preliminary assessment of clinical activity. To date, 26 patients (22 with imatinib resistance, 4 with imatinib intolerance; average CML duration 6.1 years) have been followed for greater than 4 weeks and are eligible for assessment of hematologic benefit. 22 patients had detectable BCR-ABL kinase domain mutations prior to starting BMS-354825. All 26 patients have been treated with doses of 35 mg per day or greater and have had clinical benefit, including 19 with complete hematologic responses (73%). Of the 7 partial responders, two subsequently had disease progression, one of whom had expansion of a CML subclone containing the imatinib-resistant T315I mutation in BCR-ABL, which also confers resistance to BMS-354825 in preclinical studies. The other 5 partial responders are now being treated with higher doses to attempt conversion to complete hematologic response. 11 of 21 patients (52%) treated for greater than 3 months have cytogenetic benefit, including 6 major (1-35% Ph+), 1 minor (36-65% Ph+) and 4 minimal (66-95% Ph+) cytogenetic responses. One patient has achieved complete cytogenetic response. Dose escalation continues, and phase II studies in chronic, accelerated and blast crisis CML are currently being initiated. These data provide compelling evidence supporting the safety and efficacy of BMS-354825 in imatinib-resistant chronic phase CML.

Abstract #1 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: STI571 resistant

Sunday, December 5, 2004, 01:30 PM

Plenary Session (1:30 PM-4:00 PM)

[617] Chronic Myeloid Leukemia (CML) in Childhood - Results of the Multicenter-Trial CML-paed. Session Type: Oral Session

Meinolf Suttorp, Alexander Claviez, Yvonne Martiniak, Thomas Klingebiel, Dietrich Niethammer, Helmut Gadner, Chris Peters, Hartmut Kabisch, Bernhard Kremens, Felix Zintl, Guenter Henze, Ulrich Goebel. For the CML Study Group CML-paed. Depts of Pediatrics and BMT, University Hospitals, Dresden, Germany; Kiel, Germany; Frankfurt, Germany; Tuebingen, Germany; St. Anna Kinderspital, Vienna, Austria; Hamburg, Germany; Essen, Germany; Jena, Germany; Berlin, Germany; Duesseldorf, Germany

CML is a rare disease in childhood and hematopoietic stem cell transplantation (SCT) remains the only proven option for cure of young patients (pts). We here report the results of the GPOH-trial "CML-paed". From December 1995 to June 2004 pts younger than 19 years (median age: 11.4 yrs) with Philadelphia-chromosome positive CML (n=193; 99 boys, 94 girls) were treated by hydroxyurea ± interferon and scheduled for SCT from an HLA-matched family donor within 6 months after diagnosis (Dx) and from an unrelated donor within 12 months. 85% of the pts were diagnosed in chronic phase (CP). Six pts (3%) died from disease without SCT with a median interval from Dx to death of 6.5 months (range 0.5-12 months) and 25 pts are still searching for a donor. 168 pts underwent SCT (n=50 HLA-matched related; n=69 HLA-matched unrelated (MUD); n=18 HLA-mismatched related; n=31 HLA mismached unrelated) in CP (n=139), in accelerated phase (AP, n=9), in blast crisis (BC, n=9), or in 2. CP (n=10). Probability of overall survival (OS) was 75 % if SCT was performed <7 months after Dx (n=53 pts) and 60 % (n=100 pts) if pts were transplanted later, however, this difference was statistically not significant. Conditioning regimens included either total body irradiation (n=82) or busulfan (n=80) resulting in no statistically different impact on OS. 5-year OS was 82 % for SCT from HLA-matched related and 55% for HLA-MUD-SCT reflecting a higher transplant-related mortality for the latter (p=.0017). After SCT from HLA-mismached unrelated and HLA-mismatched related donors, OS was 56% and 50%, respectively. 12 out of 168 pts (12%) relapsed following SCT after a mean interval of 11 months (range: 1-137 mos) and 9 of them so far have died of CML. Outcome was inferior if SCT was performed in advanced stages of CML (OS of all pts in CP: 67%; in AP: 55%, in BC: 21%, respectively). During the last decade the 3-year OS after SCT from HLA-matched unrelated donors improved gradually from 45 % before the year 1994, to 53 % in the period 1995 to 1999 and to 62 % after 2000, respectively. This large series of pts from a controlled trial shows an excellent OS of 82% for pediatric pts with CML undergoing SCT from matched sibling donors and constantly improving results during the last decade in the setting of MUD-SCT.

Abstract #617 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: Chronic myeloid leukemia|Children|Allogeneic hematopoietic stem cell transplant

Monday, December 6, 2004, 04:00 PM

Simultaneous Session: Matched Related Donor Transplantation (3:30 PM-5:30 PM)

[24] Feasibility of Imatinib Combination Therapies in a Randomized Trial for Chronic Myeloid Leukemia: The German CML-Study IV - Pilot Phase. Session Type: Oral Session

Ute Berger, Andreas Hochhaus, Andreas Reiter, Markus Pfirrmann, Claudia Schoch, Gerhard Ehninger, Thomas Fischer, Alois Gratwohl, Joerg Hasford, Hermann Heimpel, Dieter K. Hossfeld, Hans-J. Kolb, Stefan Krause, Christoph Nerl, Hans Pralle, Andreas Tobler, Rüdiger Hehlmann, the German CML-Study Group. III. Med. Klinik, Fakultät f. Klin. Med. Mannheim der Universität Heidelberg, Mannheim, Germany

The advent of imatinib has considerably changed treatment in chronic myeloid leukemia (CML). Although response rate and duration of response with imatinib monotherapy continue to be impressive, the majority of patients (pts) in complete cytogenetic remission (CCR) retain BCR-ABL transcripts as markers of residual disease and potential cause of relapse. In addition rapid evolvement of blast crises from CCR has been reported. Therefore, we designed an investigator-initiated phase IV prospective trial aiming to address the role of imatinib in combination with interferon alpha (IFN) or Ara-C and treatment intensification with high dose imatinib. In July 2002, the German CML-Study Group has activated the four-armed randomized controlled trial comparing imatinib 400 mg/d with imatinib+IFN, imatinib+Ara-C and imatinib after IFN failure in newly diagnosed pts with chronic phase CML. Randomization is stratified according to prognostic risk groups and not biased by consecutive allogeneic stem cell transplantation (SCT). High risk pts are randomly assigned to primary imatinib-based therapies including a 4th treatment arm with imatinib 800 mg/d. The treatment arm imatinib after IFN failure retains the chance of an IFN-induced CCR with 10 year-survival rates of 70-80%. In case of IFN failure pts are crossed over to imatinib. Allogeneic SCT is recommended for all pts with high risk, imatinib failure and EBMT-score 0-1. By August 2004, 429 pts were randomized: imatinib 400 mg/d (n=103), imatinib+IFN (n=130), imatinib+Ara-C (n=108), imatinib after IFN failure (n=84), and imatinib 800 mg/d (n=4). According to the New CML score, 34% of patients were low risk, 56% intermediate risk, and 10% high risk. At baseline, median WBC count was 63/nl (3.5-513), median platelet count was 385/nl (49-2,799) and median hemoglobin was 12.7 g/dl (6.1-16.6). We sought to evaluate results of the first cohort of pts (n=217) with a >12 months follow-up, recruited between 7/2002 and 5/2003 (imatinib 400 mg/d, n=52; imatinib+IFN, n=70; imatinib+Ara-C, n=49; imatinib after IFN failure, n=46). Median age was 56 yrs (16-82), 62% of pts were male. Cytogenetic data are available from 117 pts (68%) randomized to primary imatinib-based therapies. At 12 months, 104 pts (89%) achieved a major cytogenetic remission (Ph+<34%), being complete in 86 pts (74%). Quantitative RT-PCR data are available from 148 pts (87%). 56 pts (38%) achieved a ratio BCR-ABL/ABL <0.12%, which is equivalent to a 3-log reduction of the tumor load. 16 pts (11%) had at least one follow-up sample with undetectable BCR-ABL by real-time RT-PCR, in one patient additional nested RT-PCR was also negative. Cytogenetic response rates were not different between imatinib-based treatment arms. Estimated rate of freedom from progression to advanced disease was 97%. The first analysis of a prospective randomized trial with imatinib and imatinib in combination for newly diagnosed pts with CML has proven feasibility of imatinib combinations in addition to high response rates. The intention of combination therapy is to delay or avoid treatment resistance. Long-term observation will demonstrate whether these promising results will be maintained and will have the potential to improve survival of CML pts.

Abstract #24 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: Clinical trial|Cytogenetics|Quantitative molecular analysis

Sunday, December 5, 2004, 05:45 PM

Simultaneous Session: CML - Clinical Trials with Tyrosine Kinase Inhibitors (4:30 PM-6:00 PM)

[22] A Phase I/II Study of AMN107, a Novel Aminopyrimidine Inhibitor of Bcr-Abl, on a Continuous Daily Dosing Schedule in Adult Patients (pts) with Imatinib-Resistant Advanced Phase Chronic Myeloid Leukemia (CML) or Relapsed/Refractory Philadelphia Chromosome (Ph+) Acute Llymphocytic Leukemia (ALL). Session Type: Oral Session

Francis Giles, H. Kantarjian, B. Wassmann, J. Cortes, S. O'Brien, C. Tanaka, P. Rae, W. Mietlowski, A. Romano, L. Alland, M. Dugan, M. Albitar, O. Ottmann. Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX, USA; J.W. Goethe Universitat, Frankfort, Germany; Novartis Pharmaceuticals Corporation, East Hanover, NJ, USA; Quest Diagnostic Nichols Institute, San Juan Capistrano, CA, USA

AMN107 is a novel aminopyrimidine ATP-competitive inhibitor of Bcr-Abl. In proliferation assays AMN107 is ≥10-fold more potent than IM against Bcr-Abl expressing cell lines. AMN107 is effective against cell lines expressing the following IM-resistant Bcr-Abl mutants: Glu255Val, Phe317Leu, and Met351Thr. In addition, preliminary studies indicate that AMN107 has similar potency to IM against c-Kit and PDGFR-dependent cell proliferation. The↑potency and broader spectrum of activity of AMN107 against Bcr-Abl, relative to IM, may result in clinical benefit for pts with CML or Ph+ ALL. In the phase I portion of this phase I/II study, pts with IM-resistant CML-AP, CML-BC, and Ph+ ALL were eligible for treatment with AMN107 as an oral daily dose. 21 pts [median age:61 yrs (range 29-77); 15 male 6 female; performance status: 0(12 pts), 1(6 pts) or 2(3 pts)] have been enrolled in the following dose cohorts (mg/day): 50(7 pts), 100(7 pts), 200(7 pts) and have been on treatment for 8-70 days. Disease types: CML-AP (12 pts), CML-BC (6 pts), Ph+ ALL (3 pts). Intra-pts dose escalations were permitted for persistent disease in peripheral blood and/or marrow. 6/7 pts in the 50mg dose level, and 7/7 pts in the 100mg dose level have dose-escalated. No AMN107-related AE have been observed. Biologic activity, defined as at least a 50% ↓ in blasts or basophils in the peripheral blood and/or marrow lasting for at least 7 days was observed in 0/7 pts treated with 50mg/day, 4/13 pts treated with 100mg/day, and 7/15 pts treated with 200mg/day. Of the 7 pts who demonstrated biologic activity at 200mg/day, 2 pts with CML-AP had complete hematologic responses in marrow, and 1 pts with CML-AP had return to CP in marrow. Pts were not pre-selected for treatment based on mutational status of Bcr-Abl. Mutational analysis is being performed on all pts and will be correlated with response. Initial data reveal Bcr-Abl mutations in the majority (> 80%) of baseline pts samples. Preliminary data from the 50mg cohort comparing baseline peripheral blood samples with day 2 samples showed: significant ↑ in apoptosis as determined by mitochondrial potential, reduction in proliferation of CD34+ cells as measured by BrdU incorporation, and significant reductions in STAT1 phosphorylation. Reduction in CRKL phosphorylation in CD34+ cells was observed. Similar changes were noted in marrow. PK samples were collected on days 1, 2, 8, 15, 22 & 28 of cycle 1 and at time of any intra-pts dose escalation. Pharmacokinetics after 1 daily oral dose of AMN107 were characterized as little accumulation after multiple administrations with moderate inter-pts variability in exposure. Peak concentrations of AMN107 were generally achieved by 3 hrs post-dose. Preliminary PK data support 1-daily dosing. This phase I study, AMN107 given orally appears to be well tolerated with biologic effects in some pts treated with ≥100mg/day & marrow responses in some pts treated with 200mg/day. Once MTD has been determined, pts will be enrolled to multiple expansion cohorts in the phase II portion to assess activity.

Abstract #22 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: Chronic myeloid leukemia|Philadelphia chromosome|Imatinib resistance

Sunday, December 5, 2004, 05:15 PM

Simultaneous Session: CML - Clinical Trials with Tyrosine Kinase Inhibitors (4:30 PM-6:00 PM)

[1008] Major Cytogenetic Responses to BMS-354825 in Patients with Chronic Myeloid Leukemia Are Associated with a One to Two Log Reduction in BCR-ABL Transcript. Session Type: Poster Session 162-I

Neil P. Shah, Susan Branford, Timothy P. Hughes, John M. Nicoll, Arthur P. Decillis, Charles L. Sawyers. Medicine, The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Institute of Medical and Veterinary Science, Adelaide, South Australia, Australia; Oncology Global Clinical Research, Bristol-Myers Squibb Company, Wallingford, CT, USA; Howard Hughes Medical Institute, Los Angeles, CA, USA

The success of imatinib for the treatment of chronic myeloid leukemia (CML) has created a need for a sensitive and accurate method of monitoring disease response and burden. Quantitative PCR (Q-PCR) has been previously shown to correlate well with cytogenetic response in patients treated with imatinib, whereby a one-log reduction in BCR-ABL transcript level corresponded well with attainment of a major cytogenetic response (MCyR) and a two-log reduction correlated with a complete cytogenetic response (CCyR) (Branford et al, Leukemia 17:2401, 2003). BMS-354825 is a novel orally bioavailable SRC/ABL kinase inhibitor with impressive activity against imatinib-resistant BCR-ABL mutant isoforms in vitro (Shah et al, Science 305:399, 2004). The compound is presently undergoing evaluation in phase I clinical trials (see Sawyers et al, Talpaz et al, abstracts submitted for this meeting). We sought to address whether cytogenetic responses in patients treated with BMS-354825 correlated with reduction in BCR-ABL transcript levels as determined by Q-PCR. Of 13 evaluable imatinib-resistant/intolerant patients with chronic phase CML treated at UCLA, four have attained a MCyR. Achievement of MCyR corresponded with a one to two-log reduction in BCR-ABL transcript as assessed by Q-PCR. In the majority of cases, a substantial reduction in BCR-ABL transcript was detected four weeks after initiation of BMS-354825. Overall, the median reduction in BCR-ABL transcript level after four weeks of therapy was 32%. Three of these patients had developed resistance to imatinib, and two harbored the common imatinib-resistant M351T mutation. Of the nine patients who have failed to achieve a MCyR, none have achieved a one log reduction in BCR-ABL transcript level. We conclude that similar to imatinib, BMS-354825-associated MCyR in chronic phase CML is highly associated with a one to two-log reduction in BCR-ABL transcript level. Furthermore, Q-PCR offers a rapid and reliable method to assess for disease response in this setting, which promises to be of significant clinical value. Although the maximal tolerated dose of BMS-354825 has yet to be determined, the compound is clearly capable of substantially reducing disease burden in patients with imatinib-resistant CML. Updated Q-PCR data from all chronic, accelerated, and blast crisis-phase patients on study at UCLA will be presented.

Abstract #1008 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: Tyrosine kinase inhibitor|STI571 resistant|Ph chromosome

Saturday, December 4, 2004, 06:00 PM

Poster Session: CML - Disease Evolution and Therapy (6:00 PM-7:30 PM)

[23] Four Years of Follow-Up of 1027 Patients with Late Chronic Phase (L-CP), Accelerated Phase (AP), or Blast Crisis (BC) Chronic Myeloid Leukemia (CML) Treated with Imatinib in Three Large Phase II Trials. Session Type: Oral Session

Richard T. Silver, Moshe Talpaz, Charles L. Sawyers, Brian J. Druker, Andreas Hochhaus, Charles A. Schiffer, Francois Guilhot, John M. Goldman, B. Douglas Smith, Manisha Mone, Tillmann Kranhnke, Hagop M. Kantarjian. Hematology/Oncology, New York Weill Cornell Medical Center, New York, NY, USA; on behalf of the International STI571 CML Study Group; Clinical Oncology, Novartis Pharmaceuticals, East Hanover, NJ, USA

Background

This report updates the results of 3 large phase II studies of the orally available BCR-ABL tyrosine kinase inhibitor imatinib for patients (pts) in AP, BC and late chronic phase (L-CP) CML failing prior interferon therapy (Kantarjan et al, ASH 2003; Talpaz et al, ASH 2003). Methods

Between August 1999 and June 2000, 1027 pts were enrolled in phase II trials for CML in L-CP (n=532), AP (n=235) or BC (n=260). Pts in L-CP were treated with 400 mg/day and pts in AP or BC with either 400 or 600 mg/day. Dose escalation up to 800 mg/d was allowed in the late-chronic phase study. Pts with a confirmed diagnosis of AP (n=181), BC (n=229) and late-chronic phase (n=454) were evaluated for efficacy. All pts were evaluated for safety. The median time from initial diagnosis to study entry was 32 months for L-CP pts.

Results

As of 31-Jul-03, 5% patients with BC, 25% of CML-AP and 64% of L-CP patients still remain on treatment.

At the recommended dose of 600 mg, an estimated 40% (AP) and 7% (BC) of patients remained progression-free at 36 months, and an estimated 55% (AP) and 14% (BC) patients were alive at 36 months after initiation of imatinib. The 3-year survival rates for pts with AP with a major cytogenetic response at 3 months were 85% vs. 52% for pts with no response (p<0.001). In L-CP patients with a median follow-up of 40 months, 65% of patients achieved a major cytogenetic response, which was complete in 52%. The cytogenetic responses were durable with an estimated 82% of the pts in continuos major cytogenetic response at 3 years. The estimated rates of progression-free survival and overall survival at 3 years were 80% and 88%. Pts with at least a minor cytogenetic response at 6 months (≤65% Ph+ cells) had an estimated 3-year survival rate of 96% vs. 86% for pts with a minimal response and 81% for pts with no cytogenetic response (p<0.001).

Conclusion

In large phase II studies, continuous imatinib treatment is safe and has improved progression-free survival of patients at all stages of CML. Responses to imatinib are durable and are predictive of long-term outcomes. These results will be further updated at the meeting using a data base lock planned for 20-Sept-04 (using data collected up to 31-July-04, i.e. more than 4 years after the last pts enrollment).

Abstract #23 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: Chronic myeloid leukemia|Imatinib|Clinical trial

Sunday, December 5, 2004, 05:30 PM

Simultaneous Session: CML - Clinical Trials with Tyrosine Kinase Inhibitors (4:30 PM-6:00 PM)

[2930] Sudden Blastic Transformation (SBT) in Patients (pts) with Chronic Myeloid Leukemia (CML) Treated with Imatinib Mesylate. Session Type: Poster Session 200-III

Marieberta Vidal, Hagop Kantarjian, Susan O'Brien, Mary Beth Rios, Srdan Verstovsek, Jorge Cortes. Leukemia, U.T. M.D. Anderson Cancer Center, Houston, TX, USA

Imatinib has become standard therapy for pts with CML in chronic phase (CP). SBT has been reported in pts receiving IFN-α, at a rate of 0.5% to 2.5% during the first 3 years of therapy. There is little information on the occurrence of SBT among pts treated with imatinib. Here we report 3 pts who developed SBT, defined as occurring after being found in complete cytogenetic remission (CG CR). These 3 pts represent 0.5% of 557 pts who received imatinib at MD Anderson for chronic phase CML. The total population has been followed for a median of 33 months (range, 1 to 56). Pt #1 was a 54 yr old female with a variant Ph translocation, t(9;22;19;10) (q34;q11.2;p13.1;q22). Sokal risk was low. She started imatinib 400mg/day within 4 mos from diagnosis, achieved a CG CR within 3 mos and was still in CG CR after 9 mos with BCR-ABL/ABL 0.66%. On routine follow-up at 12 mos she was found in myeloid blast phase with 48,XX,+8,t(8;21)(q22;q22),t(9;22;19;10) (q34;q11.2;p13.1;q22), +der(22)t(9;22;19;10) in all 20 metaphases. She received standard induction chemotherapy followed by bone marrow transplantation and is alive and in CR after 24+ months. Pt #2 was a 51 yr old female initially treated with IFN-α. She achieved a CG CR but discontinued therapy because of toxicity after 18 mos. Fourteen mos after stopping IFN-α she had a CG recurrence (35% Ph-positive) and was started on imatinib 400mg/day. Three mos later she was in CG CR and BCR-ABL was undetectable by nested PCR; a similar result was found after 9 mos of therapy. 9 mos later (18 mos after start of imatinib) she had a lymphoid SBT (precursor B-cell). CG showed 45,XX,-8, t(9;22) (q34;q11.2), -20,+mar in one metaphase, and 11 metaphases were diploid. No ABL mutations were identified. She achieved CR with HCVAD + imatinib and is currently receiving a BMT. Patient #3 was a 27 yr old pt who received imatinib 800 mg/d as first line of therapy for CML in CP with intermediate Sokal risk score. Three mos after start of therapy he was in CG CR and repeated analyses showed continued CG CR up to mo 15, with the lowest BCR-ABL/ABL 0.12 at mo 6. On mo 18 he had a lymphoid SBT (precursor B phenotype) with 43-46,XY,-7,-8,i(9)(q10),t(9;22)(q34;q11.2),-13,-17,-21,+der(22)t(9;22),+mar in 13 metaphases and one diploid metaphase. No ABL mutations were identified. He was treated with HCVAD + imatinib and achieve a CR, becoming undetectable for BCR-ABL by nested PCR. He is undergoing a BMT. In pts 2 and 3, transformation was associated with a sudden drop in platelet counts. These isolated events should alert the physicians to continued monitoring of pts on imatinib and consider marrow studies in the event of late, unexpected peripheral blood count changes. Still, SBT is rare, probably less common that seen with IFN-α therapy.

Abstract #2930 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: Chronic myeloid leukemia|Imatinib|Transformation

Monday, December 6, 2004, 05:30 PM

Poster Session: CML - Clinical and Biological Insights (5:30 PM-7:00 PM)

[20] Hematologic and Cytogenetic Responses in Imatinib-Resistant Accelerated and Blast Phase Chronic Myeloid Leukemia (CML) Patients Treated with the Dual SRC/ABL Kinase Inhibitor BMS-354825: Results from a Phase I Dose Escalation Study. Session Type: Oral Session

Moshe Talpaz, Hagop Kantarjian, Neil P. Shah, Nicholas Donato, John Nicoll, Stephen A. Bai, Fei Huang, Edwin Clark, Arthur P. DeCillis, Charles Sawyers. Department of Leukemia, MD Anderson Cancer Center, Houston, TX, USA; Hematology/Oncology, David Geffen School of Medicine at UCLA/Howard Hughes Medical Institute, Los Angeles, CA, USA; Bristol-Myers Squibb, Wallingford, CT, USA; Equal Contribution

BMS-354825 is a novel, orally available, dual SRC/ABL kinase inhibitor with 100-fold greater potency to inhibit BCR-ABL in vitro than imatinib and has in vitro and in vivo preclinical activity against 14 of 15 imatinib resistant BCR-ABL mutants (Shah et al, Science, 305:399, 2004). Here we report the phase I clinical results of BMS-354825 in Philadelphia chromosome positive accelerated phase (AP) and blast phase (BP) CML patients who had hematologic progression or intolerance while being treated with imatinib. As of Aug 6, 2004, 17 patients (6 with AP; 11 with BP) have been treated in 3 cohorts with doses ranging from 35 mg BID (1 patient) to 70 mg BID of BMS-354825. BMS-354825 is rapidly absorbed with peak concentrations achieved within 2 hours and a terminal phase half-life of about 5 hours. Consistent, rapid and sustained inhibition of LYN kinase, a member of the SRC family of tyrosine kinases, has been demonstrated.

Of the 11 BP patients, 7 have had hematologic response: 3 complete hematologic response (CHR), 2 ‘no evidence of leukemia’ (NEL), and 2 ‘return to chronic phase’ (RTC). Three additional patients have had significant hematologic improvement despite being on treatment only a short period of time (10-23 days). One patient with extramedullary disease was stable. Cytogenetic data is available for 8 of the 11 BP patients. Four patients had major cytogenetic response, 2 patients had a minor cytogenetic response and 2 patients had no response. BCR-ABL mutation data is available for 2 patients: one patient did not have a mutation and one patient who had a non-sustained CHR was found to have a E355G mutation.

Three of 6 AP patients have had hematologic response: 2 CHRs and 1 NEL. Two patients are too early to assess. One patient demonstrated resistance to BMS-354825 due to a T315I mutation in BCR-ABL found in 8 of 10 clones. This mutation confers resistance to BMS-354825 in preclinical studies. BCR-ABL mutation status is available for 3 additional AP patients: 2 patients had no mutations identified and 1 patient in CHR had M351T/A imatinib-resistant mutations. Of 3 patients for whom early cytogenetic data is available, 1 had a minor cytogenetic response (40% Ph+).

To date BMS-354825 has been very well tolerated. Two patients in blast phase had evidence of mild tumor lysis syndrome. Dose escalation is continuing and phase II studies in chronic, accelerated and blast phase CML are currently being initiated. Further studies are required to establish LYN’s potential role in imatinib-resistant CML. The clinical data demonstrate that BMS-354825 can frequently override imatinib resistance in advanced CML, and provide compelling evidence supporting the safety and efficacy of BMS-354825 in imatinib-resistant accelerated and blast phase CML.

Abstract #20 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: Chronic myeloid leukemia|STI571 resistant|Phase I

Sunday, December 5, 2004, 04:45 PM

Simultaneous Session: CML - Clinical Trials with Tyrosine Kinase Inhibitors (4:30 PM-6:00 PM)

[272] Clinical Significance of Molecular Monitoring in Chronic Myeloid Leukemia (CML) in Chronic Phase (CP) with Imatinib Therapy. Session Type: Oral Session

Jorge Cortes, Moshe Talpaz, Susan O'Brien, Dan Jones, Raja Luthra, Guillermo Garcia-Manero, Francis Giles, Jenny Shan, Srdan Verstovsek, Mary Beth Rios, Hagop Kantarjian. Leukemia, U.T. M.D. Anderson Cancer Center, Houston, TX, USA; Hematopathology, U.T. M.D. Anderson Cancer Center, Houston, TX, USA

Most patients (pts) with CML in chronic phase treated with imatinib achieve a major cytogenetic (CG) remission, and increasing numbers of pts are achieving molecular responses. To determine the clinical significance of molecular responses in these pts, we analyzed the results of quantitative PCR monitoring among 280 pts with CML in CP who achieved a complete CG remission with imatinib therapy (117 after IFN-α failure, 163 previously untreated). Pts have been followed for a median of 31.2 mo (range, 3 to 52 mo). The median BCR-ABL/ABL ratio before the start of therapy was 37.43 (range, 0.004 to 170.53). A major molecular response (i.e., BCR-ABL/ABL ratio <0.05%) was achieved in 174 (62%) pts, and transcripts became undetectable (i.e., complete molecular response) in 95 (34%). Median time to major molecular responses was 10 mos (range, 2.8 to 46 mos) and for complete 16.7 mos (range, 3 to 48 mos) but responses have occurred as late as 48 mos with no evidence of a time after which responses do not improve any more. In a multivariate analysis, clinical characteristics associated with an increased probability of achieving a major molecular response were early chronic phase previously untreated (p=.03), no splenomegaly (p=.03), and ≤90% Ph-positive metapahases at the start of therapy (p=0.05). Only 9 of 166 (5%) patients who achieved a major molecular response and have had subsequent cytogenetic analysis have lost their cytogenetic response, compared to 25 of 68 (37%) of those who did not achieve this response (p<0.0001). Only 3 of 82 (4%) with complete molecular response have lost their cytogenetic response. Patients achieving a major molecular response 12 mos after the start of therapy have a significantly better complete cytogenetic remission duration than those not achieving this response at this time point, and similar but not statistically significant trends can be detected with earlier responses (at 3 and 6 mos). Pts with more than a 1-log-reduction in transcript levels after 3 mos of therapy have a 90% probability of achieving a 3-log reduction at 24 mos, compared to 55% for those with ≤1-log decrease (p=0.0002). We then evaluated the significance of an increasing trend in transcript levels. None of the 44 pts with an increase of <0.05 has lost the complete CG remission, compared to 6 of 33 (18%) with an absolute increase of 0.05 to 1, and 5 of 11 (45%) with an increase of >1.0 (p=0.0001). The probability of cytogenetic relapse is particularly high for patients who never achieved a major molecular remission. We conclude that achieving a major molecular response, particularly within the first year of therapy with imatinib, is predictive of a durable cytogenetic remission and should be the goal of therapy with imatinib. Increasing transcript levels after achieving a complete CG response predict for a relapse in patients who did not achieve a major molecular response.

Abstract #272 appears in Blood, Volume 104, issue 11, November 16, 2004 Keywords: Chronic myeloid leukemia|Imatinib|BCR-ABL

Monday, December 6, 2004, 11:15 AM

Simultaneous Session: CML - Molecular Monitoring of Residual Disease and Bcr-Abl Kinase Mutation (11:00 AM-12:30 PM)