Time Of Chronic Myeloid Leukemia Diagnosis Research Articles

Characteristics, Outcomes, Tfr Rates in Young Adults with Chronic Myeloid Leukemia in the Tyrosine Kinase Inhibitor Era: A French Observational Study

Introduction. Chronic myeloid leukemia (CML) is a myeloproliferative disorder with a median age of approximately 60 years. Our study emphasizes the fact that CML can present at younger ages. These patients have significantly different life challenges compared with older patients. The 2020 update of the ELN recommendations mentioned that“ TFR may be the main goal for any patient, irrespective of age, but it is clear that the younger the patient the stronger the case for achieving TFR”. We report here the main characteristics and TFR data in CML young adults. Methods. The French CML group (FI-LMC) initiated an observational study (CCTIRS no. 14.745) to describe the characteristics of CML in young adult patients in terms of characteristics at diagnosis, treatment choices, tolerance, adherence, therapeutic response, evolution and survival. Patients ranging from 18 to < 30 years with newly diagnosed CML in chronic phase (CP) or accelerated phase (AP) treated with a tyrosine kinase inhibitor (TKI) in first line were eligible for enrolment. Results. The observatory included 253 unselected young adults from 22 centers with newly diagnosed CML in CP (n=246) or in AP (n=7) among which 51.6% were treated within a first line trial. At the time of CML diagnosis, the median patient age was 24 years (range, 18-29 years); 165 patients were males (63%). Median (range) values were: WBC 154.3 G/L (6.5; 841); platelets 374 G/L (51; 1799), hemoglobin 11.3 g/dL (4.1; 18.3), blast cells 1 % (0; 20), spleen below costal margin 4 cm (0; 30). In CP patients, Sokal score was low in 132 (53.6%) patients, intermediate in 46 (18.7%), high in 37 (15.1%) and unknown in 31 (12.6%) and ELTS score was low in 142 (57.7%) patients, intermediate in 48 (19.5%), high in 22 (9%) and unknown in 34 (13.8%). Initial TKI was imatinib alone (52.4%) or in combination with IFN (2.4%) or Ara-C (0.8%), nilotinib alone (24.6%) or in combination with IFN (4%), dasatinib alone (8.2%) or in combination with IFN (0.4%), bosutinib (1.2%), ponatinib (4.8%) or asciminib (1.2%). Median follow-up is 106.2 months (range: 0.03; 279.2). Ninety-nine (39.3%) patients remained under first-line TKI at latest follow-up and 21 pts (8.3%) underwent bone marrow transplantation (BMT) for resistance or transformation. Median overall survival at 9 years is 96.9% [95% CI: 94.5- 99.4]. Event free survival without death, transformation, or BMT at 9 years is 93.1% [95% CI: 89.7- 96.7]. Six patients died, 1 from sarcoma, 5 from CML including 1 before any therapy (brain hemorrhage). We investigated the TFR strategy. In 169 patients treated for at least 5 years, 56 (33.1%) attempted TKI discontinuation. TKI free survival at 24 months is 57.9% [95% CI: 45.8- 73.2] (Figure 1). Complete analysis comparing characteristics and outcome between the 2 groups of patients (TFR vs no TFR), will be available for ASH presentation. Conclusion. Despite aggressive features including prominent splenomegaly, high WBC counts and high blast cell percentage, TFR seems achievable in young adults with CML.

Control of Ph+ and additional chromosomal abnormalities in chronic myeloid leukemia by tyrosine kinase inhibitors.

Chronic myeloid leukemia (CML) is a type of blood cancer that is known to affect hematopoietic stem cells. The presence of the Philadelphia chromosome (Ph+) is the major characteristic of CML. A protein expressed by the Philadelphia chromosome shows elevated tyrosine kinase activity and is considered a tumorigenic factor. The first line of therapy that had been established for CML was "imatinib," a potent tyrosine kinase inhibitor. Various other second- and third-generation TKIs are taken into account in cases of imatinib failure/resistance. With the subsequent rise in the development of tyrosine kinase inhibitors, optimization in the treatment of CML and amplified total survival were observed throughout TKI dosage. As the disease progresses, additional chromosomal abnormalities (ACAs) have been reported, but their prognostic effect and impact on the response to treatment are still unknown. However, some substantial understandings have been achieved into the disease transformation mechanisms, including the role of somatic mutations, ACAs, and several different genomic mutations that occur during diagnosis or have evolved during treatment. The acquisition of ACAs impedes CML treatment. Due to additional chromosomal lesions, there are greater chances of future disease progression at the time of CML diagnosis beyond the Ph+ translocation. The synchronous appearance of two or more ACAs leads to lower survival and is classified as a poor prognostic group. The key objective of this review is to provide detailed insights into TKIs and their role in controlling Ph+ and ACAs, along with their response, treatment, overall persistence, and survival rate.

Family Planning and Pregnancy in Patients with Chronic Myeloid Leukemia.

The goal of this review is to summarize what is known about pregnancy in women with chronic myeloid leukemia (CML): there are very few guidelines regarding how to treat women who are pregnant at the time of CML diagnosis, and similarly, few guidelines regarding family planning for women already on tyrosine kinase inhibitor therapy who might want to start family planning. Most patients with CML achieve excellent control with first line tyrosine kinase inhibitor therapy that includes either imatinib, dasatinib, nilotinib, or bosutinib. For men, tyrosine kinase inhibitor (TKI) therapy does not affect sperm number or function, and female partners of men on therapy who become pregnant do not have an increased risk of miscarriage or babies with fetal malformation. However, for women, all TKIs are teratogenic and should be avoided at least in the first trimester of pregnancy. However, a small study suggests that women who have achieved a stable deep response therapy can safely stop therapy prior to a planned pregnancy and may not need any intervention during the pregnancy. Another small study suggests that nilotinib and imatinib have the lowest rate of transfer across the placenta. Providing well-documented guidelines for women with CML is challenging as TKI therapy is teratogenic. However, valuable information can be gained from small series of patients as summarized here.

Emergence of Chronic Myeloid Leukemia in Patients with Myeloproliferative Neoplasms: A Single-Institution Experience

Introduction: Chronic myeloid leukemia (CML) is characterized by the presence of the BCR-ABL1 translocation and is typically distinct from other myeloproliferative neoplasms (MPN) including polycythemia vera (PV), essential thrombocythemia (ET) and myelofibrosis (MF). Concurrent diagnosis of CML and MF is uncommon and infrequently described in case reports.1 Moreover, very few cases have been described of CML occurring after an established diagnosis of MPN.2-3 Due to the rarity of concurrent CML and MPN, management strategies in this population are not defined. In addition, the latency time from the emergence of BCR-ABL1 positive clones to a clinical diagnosis of CML in this setting is largely unknown. To address these questions, we interrogated our institutional experience and retrospectively analyzed available specimens. Methods: We collected information on patients seen at Massachusetts General Hospital (MGH) from January 1 2012 to January 1 2022 for CML occurring after an established diagnosis of MPN. Available stored samples were retrospectively tested for BCR-ABL1 with a fusion transcript assay (MGH Center for Integrated Diagnostics, Boston, MA). Results: We identified four patients with CML preceded by MPN (Table 1). Three patients had prior MF, diagnosed 4.3-7.6 years before the onset of CML; two of these had post-ET MF. Patient #4 had ET diagnosed 4 years prior to onset of CML, then went on to develop MF 4.9 years after CML diagnosis. None of the patients were on JAK inhibitors, hydroxyurea or interferon at the time of CML diagnosis. All patients had a leukocytosis with characteristic features on the differential prompting evaluation for CML. The median white blood cell count was 45.83 x 10^9/L (range 27.49-121.02). All four patients had an elevated basophil count (median 2.99 x 10^9/L, range 1.1-22.99) and two had an elevated eosinophil count (median 1.11 x 10^9/L, range 0.55-44.17). Regarding MPN driver mutations, one patient had a JAK2 V617F, one patient had a CALR exon 9 deletion, and two patients had no identifiable mutations on extended next-generation sequencing. For CML treatment, three patients received dasatinib (two with 100 mg daily, one with 50 mg daily), whereas one received nilotinib (150 mg twice daily). Two achieved a major molecular response (MMR) (at 7 and 8 months); one had an early molecular response at 6 months (last follow-up); one (with e13-a3 transcript) could not be quantified on a standard PCR assay but achieved a complete cytogenetic response by 4 months. At the time of last follow-up, two patients were in MMR on tyrosine kinase inhibitors (TKI), whereas two underwent allogeneic hematopoietic cell transplantation (alloHCT), primarily for progression of MF. We retrospectively interrogated available samples for evidence of the BCR-ABL1 translocation prior to a clinical diagnosis of CML. Patient #2 was followed at MGH for MF and thus had available samples. We identified BCR-ABL1 transcripts in the peripheral blood three months prior to his clinical diagnosis of CML (unable to be quantified due to e13-a3 transcript); there were no available samples from earlier in his disease course for testing (Figure 1). Discussion: CML can emerge in patients with MPN. Herein, we describe four cases of this phenomenon. Signs of CML evolution included marked leukocytosis, as well as basophilia and eosinophilia. Despite underlying MF, three patients tolerated full-dose TKI and achieved molecular responses early in their disease course. However, MPN progression remained a significant challenge, with two patients ultimately requiring an alloHCT. Of note, we found evidence of BCR-ABL1 in the peripheral blood three months prior to clinically apparent CML in one patient. Experiments using single cell techniques in patients with concurrent MPN and CML would provide insights into the clonal architecture and are in planning stages.

Association between Bariatric Surgery and Outcomes in Patients with Chronic Myeloid Leukemia Treated with Oral Tyrosine Kinase Inhibitors

Association between Bariatric Surgery and Outcomes in Patients with Chronic Myeloid Leukemia Treated with Oral Tyrosine Kinase Inhibitors

Spectrum of BCR-ABL Mutations and Treatment Outcomes in Ethiopian Imatinib-Resistant Patients With Chronic Myeloid Leukemia.

PURPOSEDespite the successes achieved in chronic myeloid leukemia (CML) with tyrosine kinase inhibitor (TKI) therapy, resistance remains an obstacle. The most common mechanism of resistance is the acquisition of a point mutation in the BCR-ABL kinase domain. Few studies have reported African patients with CML in regard to such mutations. We here report the types of BCR-ABL mutations in Ethiopian imatinib-resistant patients with CML and their outcome.PATIENTS AND METHODSPatients with CML with a diagnosis of imatinib resistance who were tested for BCR-ABL mutation between 2014 and September 2019 were included.RESULTSA total of 962 cases of CML on imatinib therapy were reviewed and 164 cases of failure were found. Of these, only 31 cases (19%) had mutation analysis performed. Most cases (94%) were secondary failures. At the time of CML diagnosis, the median age was 33 years and the majority presented with features of advanced-phase disease. Of the 31 patients, 22 mutations were found (65%). The types of mutations detected were as follows: non–P-loop mutations 36% (11), P-loop mutations 13% (four), and alternatively spliced BCR-ABL variants 23% (seven). The splice variant frequently detected was BCR-ABL35INS (20%). Twenty-six of the 31 patients (84%) were switched to second-line TKIs, whereas in four patients (13%), imatinib dose escalation was done. Overall, the outcome revealed that 16 patients (52%) were alive with complete hematologic response, whereas 12 patients (39%) had died. All patients who expressed BCR-ABL135INS were treated with second-line TKIs, and two of them (33%) had died because of disease progression.CONCLUSIONIn Ethiopia, CML affects the young and point mutations were frequently detected in imatinib-resistant patients. BCR-ABL1 35INS was also prevalent and associated with disease progression.

Longitudinal Detection of DNMT3AR882H Transcripts in Patients with Acute Myeloid Leukemia

Introduction The DNMT3A gene is recurrently mutated in normal karyotype acute myeloid leukemia (NK-AML) and the most common alteration (65% of cases) is located at residue R882 of methyltransferase domain. DNMT3A mutations often occur in association with other mutations such as FLT3 and NPM1 and while it is now generally accepted that AML patients with NPM1 or FLT3 -ITD mutations have favourable and poor outcome respectively, the impact of DNMT3A mutations on survival remains controversial. Recent studies reported that DNMT3A -mutated cells are detectable in patients with AML in long-lasting complete remission, questioning whether quantification of DNMT3A levels could be used to minimal residual disease (MRD). To address this issue, we carried out sequential monitoring studies of DNMT3AR882H levels in AML patients and compared our results with those obtained with multiparametric flow-cytometry (MPFC) and NPM1 molecular status and expression levels.Methods The mutational analysis of DNMT3AR882, NPM1 and FLT3 (ITD/TKD) was assessed at diagnosis in 556 patients with de novo AML (median age: 49 years, range 16-89 years) enrolled in clinical trials conducted by the Gruppo Italiano Malattie EMatologiche dell'Adulto (GIMEMA) during the period 2012-2015. DNMT3AR882H molecular status was also studied in 100 patients with chronic myeloid leukemia (CML) and in 56 elderly healthy individuals. The expression levels of DNMT3AR882H and NPM1 Type_A mutation (NPM1mutA) were longitudinally analysed by qRT-PCR in 21 AML patients. For patients achieving complete morphologic remission (CR), DNMT3AR882Hlevels were compared with those of NPM1mutA and with MRD assessed by multiparametric flow cytometry (MPFC). W e then compared the levels of DNMT3AR882H and of MPFC-MRD in follow-up BM-samples from AML patients in CR , classified as MRDneg or MRDpos, according to threshold established based on previous work from our group (Buccisano et. al. Blood 2010). Finally, we evaluated the kinetics of DNMT3AR882H, NPM1mutA and FLT3 -ITD in 9 FLT3 -ITD+ve patients, using a FLT3 -ITD patient-specific qRT-PCR, and in 6 FLT3 -wt patients.Results Expression levels of DNMT3AR882H was also studied in sorted cell subpopulations from AML and CML patients and in healthy individuals. Distinct from NPM1mutA, DNMT3AR882H expression levels did not correlate with leukemic blast proportion assessed by MPFC (Figure 1) and decreased in AML samples only after induction treatment (Figure 2), while it was constantly detectable during remission and at relapse (Figure 3). Within FLT3 -ITD+ve AML, the kinetics of DNMT3AR882H paralleled that of NPM1mutA in 3 of 9 patients only. DNMT3AR882H expression levels were constant, independent from NPM1mutA in all 6 FLT3 -wt patients. Figure 4 shows 4 exemplary cases, with stable DNMT3AR882H levels during disease course in three of them. In CML patients, the DNMT3AR882H transcript was found only during follow-up in 4/100 patients, while it was undetectable at the time of CML diagnosis. DNMT3AR882H transcript levels were constantly low in all available CML samples. As previously reported, clonal hematopoiesis of indetermined potential (CHIP) was identified in 3/56 elderly healthy individuals. Similarly low expression levels of DNMT3AR882H were detected in blast and T-lymphocyte samples obtained from AML cases at CR and relapse phases, in CML patients and healthy individuals (Figure 5 and 6). There were no differences in DNMT3AR882H expression between MRDpos and MRDneg follow-up samples. DNMT3AR882H transcripts levels in MRDpos follow-up samples were significantly lower than those of samples harvested at diagnosis (Figure 6). These data show that DNMT3AR882H mutations probably arise in very early hematopoietic precursors in the context of CHIP. Interestingly, as reported in figure 6, DNMT3AR882H expression levels were similar in samples from CML patients, healthy individuals and AML follow-up samples.Conclusions In summary, the results of our study indicate that DNMT3AR882H quantification is unreliable as a tool for AML monitoring. In fact, together with its detection in CML and healthy subjects, the presence of DNMT3AR882H at constant levels detected in AML during active disease or CR clearly point to a lack of specificity of this abnormality for the leukemic AML blast population. [Display omitted] DisclosuresCicconi:TEVA: Speakers Bureau. Lo Coco:Lundbeck: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; TEVA: Honoraria, Speakers Bureau.

Low-density lipoprotein (LDL) levels and risk of arterial occlusive events in chronic myeloid leukemia patients treated with nilotinib

Recommendations for dyslipidemia management aimed at reducing arterial occlusive events (AOEs) have been recently published. So far, no data have been reported on the management of dyslipidemia in chronic myeloid leukemia (CML) patients treated with nilotinib. We investigated 369 CML adult patients, stratified according to the new Systematic Coronary Risk Evaluation (SCORE) scoring system. Plasma levels of cholesterol, HDL, LDL, and triglycerides were measured prior to the start of nilotinib and after 3, 6, and 12months. The 5-year cumulative incidence of AOEs was 15.9%. Patients with cholesterol levels > 200mg/dL and LDL > 70mg/dL 3months after treatment showed a significantly higher incidence of AOEs (21.9 ± 4.6% vs 6.2 ± 2.5, P= 0.003). Patients belonging to the high and very high SCORE risk group showed a significant increase of AOEs (34.4 ± 6% vs 10 ± 2.1%, P< 0.001). In multivariate analysis, both high cholesterol and LDL levels and a high and very high SCORE risk remained significantly associated with the risk of AOEs (P= 0.008; HR = 3.5; 95% CI = 1.4-8.7 and P < 0.001; HR = 4.4; 95% CI = 2-9.8, respectively). Overall, 78 patients (21.1%) presented dyslipidemia at the time of CML diagnosis and 88 (23.3%) after starting nilotinib, but only 26 of them (29.5%) were treated with statins.Low LDL and cholesterol plasma levels are associated with a significant lower risk of AOEs in CML patients treated with nilotinib in the real life.

Determinants of Choice of Front-Line Tyrosine Kinase Inhibitor for Chronic Phase CML: A Study from the “Registro Italiano LMC & Campus CML”

Introduction : therapy of chronic phase (CP) chronic myeloid leukemia (CML) is based on tyrosine kinase inhibitors (TKIs) in virtually all patients. Three TKIs are approved for first-line therapy in Italy: imatinib and two second-generation (2G) TKIs, dasatinib and nilotinib. Choice of the front-line TKI is based on a combined evaluation of patient's and disease characteristics, age, risk, comorbidities and concomitant medications. Treating physician's preference and, in some cases, economic considerations, particularly after the advent of generic imatinib, may play a role in TKI selection. However, to date, few data are available on TKI use in a whole nation and on the possible drivers of treatment choice. Aim of the present work was to analyse the use of front-line TKI therapy in a large, unselected cohort of Italian CP-CML patients, correlating patient's features to drug choice. Methods: in the framework of the national Campus CML program, we retrospectively evaluated 1422 patients with CP-CML diagnosed from 2012 and 2019 in 21 haematologic Centres, mostly in academic and/or tertiary hospitals, widespread through the entire Italian territory and treated frontline with imatinib, dasatinib or nilotinib. Results: median age at diagnosis was 59.9 years [interquartile range (IQR) 47.1 - 71.7], with 317 (22.3%) patients under 45 years, 552 (38.8%) between 45 and 65 years and 553 (38.9%) older than 65 years; 821 (57.7%) patients were males. Among 1364 evaluable patients, CML risk according to Sokal score was low in 540 (39.6%), intermediate in 610 (44.7%) and high in 214 (15.7%) patients respectively; the number at low, intermediate or high risk according to the novel ELTS score among 1325 evaluable patients was 759 (57.3%), 402 (30.3%) and 164 (12.4%) respectively. Considering comorbidities, 1003 (70.6%) patients had at least one active disease at the time of CML diagnosis, the most common being hypertension (n=547, 38.5%), previous neoplasms (n=185, 13.0%), diabetes (n=150, 10.6%), chronic bronchopulmonary diseases (n=114, 8.0%), acute myocardial infarction (n=95, 6.7%), previous stroke (n=36, 2.5%) and other vascular diseases (n=98, 6.9%). Among 1335 evaluable patients, 813 (60.9%) were taking at least one concomitant medication, with 280 (21.0%) taking 3-5 drugs and 140 (10.5%) taking 6+ drugs at time of TKI start. As to the frontline therapy, 794 (55.8%) received imatinib and 628 (44.2%) were treated with 2G-TKIs, (226 dasatinib and 402 nilotinib) respectively. According to age, 2G-TKIs were chosen for majority of patients aged &amp;lt;45 (69.1%) while imatinib was used in 76.9% of patients over 65 (p&amp;lt;0.001). There was a predominance of imatinib use across all Sokal (51.1% in low, 61.3% in intermediate and 51.4% in high) and ELTS (50.3% in low, 60.4% in intermediate and 66.5%) risk categories. We observed a prevalent use of 2G-TKIs in patients presenting with higher WBC counts (55.1% if WBC &amp;gt;100,000/mm3 vs 38.2% if WBC &amp;lt;100,000/mm3; p&amp;lt;0.001), lower Hb (53.8% if Hb &amp;lt;10 g/dl vs 41.9 if Hb &amp;gt;10 g/dl; p=0.001) and bigger spleen (65.1% if spleen &amp;gt;5 cm vs 44.8% if spleen 1-5 cm vs 37.3% if spleen not palpable; p&amp;lt;0.001). There was a decreasing use of 2G-TKIs with higher number of concomitant drugs: 64.4% for 0, 47.7% for 1-2, 27.0% for 3-5 and 13.6% for &amp;gt;5 drugs, respectively (p&amp;lt;0.001). Concordantly, there was a significant higher use of imatinib in patients with hypertension (69.8%), diabetes (70.0%), COPD (73.7%), previous neoplasms (73.0%), AMI (86.3%) or stroke (97.2%) history (p&amp;lt;0.001 for all conditions). Lastly, we observed a wider use of imatinib (61.1%) in patients diagnosed in years 2018-19, compared to those of the period 2012-17 (53.7%; p=0.01). In multivariable analysis, factors correlated with imatinib use were age &amp;gt; 45 years, intermediate or high Sokal risk, presence of some comorbidities (2nd neoplasia and stroke) and number of concomitant medications. Conclusions: preliminary results of this observational study on almost 1500 patients show that around 55% of newly diagnosed Italian CP-CML patients receive imatinib as front-line therapy, and that the use of 2G-TKI is prevalent in the younger patients and in those with no concomitant clinical conditions. The counterintuitive finding of imatinib prevalence as frontline treatment in high risk patients might be explained by the older age of these patients. Introduction of the generic formulation in 2018 seems to have fostered the use of imatinib. Figure Disclosures Breccia: Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Abbvie: Consultancy; Bristol-Myers Squibb/Celgene: Consultancy, Honoraria. Cavazzini:Pfize: Honoraria; Incyte: Honoraria; Novartis: Honoraria. Saglio:Bristol-Myers Squibb: Research Funding; Pfizer: Research Funding; Incyte: Research Funding; Novartis: Research Funding; Ariad: Research Funding; Roche: Research Funding.

Similar Efficacy of Dasatinib and Nilotinib As Second-Line Therapy in Patients with Chronic Phase Chronic Myeloid Leukemia Failing Imatinib: A Retrospective, Real-Life Study

Background. Use of 2nd generation tyrosine kinase inhibitors (2G-TKIs) dasatinib (DAS) and nilotinib (NIL) in chronic phase (CP) chronic myeloid leukemia (CML) patients failing imatinib (IM) results in around 50% of sustained cytogenetic response, and around 40% major molecular response (MMR). However, these are historical data and it's unclear if there's a significant difference in efficacy of the two 2G-TKIs, especially in the long-term.Aims and methods. We retrospectively analysed 163 CP-CML patients resistant or intolerant to IM that received either DAS (n=95) or NIL (n=68) as second-line therapy. We compared the characteristics of the two groups at the time of CML diagnosis and at the time of IM failure, including the cause of switch to 2G-TKI, duration of IM therapy, IM dose escalation and Hammersmith score to predict the probability of response to 2G-TKIs. Cytogenetic and molecular responses were evaluated according to the ELN recommendations. Sustained deep molecular response (DMR) was defined as MR4 or better lasting ≥ 2 years, ongoing at the last contact, and with at least a Q-PCR test every 6 months. Time to treatment failure (TTF) was calculated from the start of 2G-TKI to any of the followings: progression to accelerated or blast phase (ABP), death for any cause at any time, treatment discontinuation for primary or secondary resistance or intolerance. Progression free survival (PFS) was calculated from the start of 2G-TKI to ABP or death. Overall survival (OS) was calculated from the start of 2G-TKI to death.Results. DAS and NIL cohorts were comparable for age, sex and risk score (Sokal and EUTOS) at diagnosis. Median duration of IM therapy was similar (DAS 19 months, NIL 14 months), but 27/95 patients (28%) had IM dose escalation before DAS compared to only 9/68 (13%) before NIL (p=0.03). There was a higher rate of switch to DAS than to NIL for secondary resistance (26/95, 27% vs 7/68, 10%; p=0.01) while more patients changed from IM to NIL due to intolerance (31/68, 46%, vs 21/95, 22% for DAS; p=0.002). Rates of primary resistance did not differ (47/95, 49% for DAS vs 28/68, 41% for NIL; p=0.37), as well as other causes of switch (1/95, 1% for DAS vs 2/68, 3% for NIL; p=0.77). Hammersmith score was almost identical in the two groups.Complete cytogenetic response (CCyR) was attained in 53/73 (73%) patients not in CCyR at the time of DAS start, and in 31/48 (65%) patients not in CCyR at the time of NIL start (p=0.46). Mean time to CCyR was similar (7.1 months for DAS and 5.3 months for NIL; p=0.30).MMR was achieved in 55/89 (65%) patients not in MMR at the time of DAS start and in 39/61 (65%) patients not in MMR at the time of NIL start (p=0.82). Again, mean time to MMR was not different in the DAS e NIL cohorts (12.4 vs. 8.5 months; p=0.14).DMR was obtained in 39/88 (44%) patients not in DMR at the time of DAS start and in 30/65 (46%) patients not in DMR at the time of NIL start (p=0.95). Sustained DMR was evaluable in 127 patients: 37 patients (29%) achieved sustained DMR, without difference between DAS (24/82, 29%) and NIL (13/45, 29%; p=1.00).With a median follow-up of 44 months (range 1-124), 5-year TTF was similar for DAS (65%, 95%CI 52-75%) and NIL (61%, 95%CI 43-74%; p=0.40) [Figure 1a]. Thirty-two of 95 patients (34%) stopped DAS due to toxicity (19/32, 59%), resistance (11/32, 31%) or other causes (3/32, 10%); 22/68 patients (32%) interrupted NIL for toxicity (11/22, 50%), resistance (8/22, 36%) or other causes (3/22, 14%). Probability of survival and progression were almost identical, with a 5-year PFS of 84% (95%CI 68-89%) for DAS and 92% (95%CI 79-97%) for NIL (p=0.27) [Figure 1b] and a 5-year OS of 89% (95%CI 78-95%) and 96% (95%CI 85-99%) (p=0.31), respectively.Conclusions. With the limits of a retrospective analysis, our data suggest similar efficacy of DAS and NIL after IM failure in CP-CML, with rates of cytogenetic and molecular responses higher than those previously reported and excellent long-term survival. Around 30% achieved sustained DMR with second-line therapy, thus being potentially candidate for TKI discontinuation. DisclosuresTiribelli:Bristol-Myers Squibb: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Ariad Pharmaceuticals: Consultancy, Speakers Bureau. Bonifacio:Ariad Pharmaceuticals: Consultancy; Pfizer: Consultancy; Bristol Myers Squibb: Consultancy; Novartis: Research Funding; Amgen: Consultancy. Fanin:Novartis: Speakers Bureau.

Comorbidity Burden and Use of Concomitant Medications at CML Diagnosis: A Retrospective Analysis of 470 Patients from the Polish Adult Leukemia Group (PALG) Registry

Background:Introducing tyrosine kinase inhibitors (TKIs) for treating chronic myeloid leukemia (CML) has changed the prognosis of this disease from an incurable malignancy to a manageable chronic condition. The need for life-long treatment with TKIs however, requires detailed knowledge of factors that could affect therapy efficacy and toxicity. TKIs are generally well tolerated, nevertheless they may be associated with the so called "off-target" effects causing specific adverse events (AEs). It has been shown that some co-morbidities may predispose towards developing certain TKIs' "off-target" AEs, which includes cardiovascular complications or pleural effusion. Furthermore, TKIs are metabolized by the CYP3A4 isoenzyme and have been reported to be substrates of ABCB1 (MDR1) and ABCG2 (BCRP) transporters. Drug interactions should therefore be considered when administering inhibitors or inducers of CYP3A4, ABCB1 and ABCG2 in combination with TKIs.Objective:The aim of this study was a retrospective assessment of the prevalence of both comorbid conditions and use of concomitant medications in a large cohort of newly diagnosed CML patients within a real-world setting.Patients and methods:Data from medical records were retrospectively analyzed on newly diagnosed adult CML patients referred to nine Polish hematological tertiary care centers. Inclusion criteria were as follows: 1) age ≥ 18 years; 2) diagnosis of chronic phase CML between January 1st 2005 and December 31st 2014.Results:Study subjects were 470 consecutive patients diagnosed with CML as per above. Patients' median age was 53.0 years (range 18.0 - 88.9 years). Two hundred sixty-one patients (55.5%) were found to have at least one comorbid condition at CML diagnosis and 268 (57.0 %) received at least one concomitant medication. The median number of concomitant therapies was one (range 0-12). In the analyzed patients cohort the most frequent comorbidities that are of importance regarding the risk of TKI' "off target" AEs included: hypertension (31%), hypercholesterolemia (11%), ischemic heart disease (10%), diabetes (9%), cardiac insufficiency (5%), history of myocardial infarction (4.5%) significant pulmonary diseases including bronchial asthma, COPD or sarcoidosis (4%) and ischemic stroke (2%). Moreover, 55 patients (11.6%) were cigarette smokers. The median body mass index (BMI) was 25, where 134/392 patients (34%) were qualified as being overweight and 86/392 patients (22%) were obese.Conclusions: Our analysis shows that more than 50% of newly diagnosed CML patients suffer comorbid conditions, and take concomitant medication at the time of CML diagnosis. Because the presence of certain comorbidities increases the risk of TKIs' "off-target" AEs, it is vital to assess and take into account these co-morbidities when selecting TKI for individual CML patients. Furthermore, potential pharmacokinetic interactions between specific TKIs and concomitant medications, as well as their overlapping toxicities have to be also considered. DisclosuresGora-Tybor:Novartis: Consultancy, Honoraria, Speakers Bureau; Incyte: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria. Sacha:BMS: Consultancy, Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau; Incyte: Consultancy, Honoraria, Speakers Bureau; Adamed: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Speakers Bureau. Grzybowska-Izydorczyk:BMS: Honoraria; Novartis: Honoraria. Seferynska:Novartis: Consultancy, Honoraria. Lewandowski:Novartis: Consultancy, Honoraria, Speakers Bureau; Incyte: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Speakers Bureau. Warzocha:Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria. Jamroziak:Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria.

Abstract 2395: Direct assessment of sequence heterogeneity in human cancers by Duplex Sequencing

Abstract The extent of heterogeneity in DNA sequence within human cancers has been difficult to fully assess, due to the absence of methods with sufficient sensitivity to detect minority variants. For example, next-generation sequencing could in principle detect sub-clonal mutations at any genomic position; however due to amplification errors and inaccuracies in the sequencing platform itself, such approaches are limited to detection of mutations present in &amp;gt;1% of cells. We have overcome this limitation by developing an approach, Duplex Sequencing, which improves the accuracy of next-generation sequencing by &amp;gt;100,000 fold. Duplex Sequencing is based upon separately tagging and sequencing the two strands of single molecules of duplex DNA. True mutations are present at the same position in both DNA strands and are complementary, whereas artifacts arising from amplification or sequencing errors are seen in only one strand. The calculated error rate of our approach is less than one artifactual mutation per billion nucleotides sequenced (ref. 1). We have also developed an enrichment approach based on sequential rounds of hybridization to biotinylated probes which enables efficient sequencing of targeted regions of the genome (ref. 2). Duplex Sequencing thereby enables exceptionally sensitive detection of sequence heterogeneity within any set of genes. We have now applied Duplex Sequencing to study of sequence heterogeneity in both normal and malignant samples. In acute myeloid leukemia (AML), we find multiple sub-clonal mutations which fall below the detection limit of conventional approaches, some of which encode mutations that can drive chemotherapy resistance and cancer progression. Our results indicate that prior studies have under-estimated the burden of sub-clonal mutations in AML by more than 1,000-fold. We have additionally studied chronic myeloid leukemia (CML); treatment of CML with inhibitors directed against the Abl kinase represents the prototypical targeted cancer therapy. With Duplex Sequencing, we find that Abl mutations are extremely uncommon at the time of CML diagnosis. In contrast, refractory patients who fail therapy frequently possess multiple sub-clonal mutations within the Abl kinase, most of which are below the resolution of conventional approaches but are readily detected with our method. In ongoing work, we have found multiple sub-clonal mutations within human prostate cancer and colon cancer, suggestive of widespread intratumor heterogeneity that may limit the efficacy of single-agent therapy in these diseases.

Emergence of Sub-Clonal Drug Resistance Mutations during CML Therapy

▪Tyrosine kinase inhibitors (TKIÕs) vastly improve survival in chronic myeloid leukemia (CML). However resistance is a common occurrence, and is most frequently mediated by point mutations in the Abl kinase. There have been conflicting reports regarding the frequency of resistance mutations in the Abl kinase at the time of CML diagnosis, with some studies indicating that a large number of resistance mutations are pre-existing in many patients. However, a high burden of pre-existing resistance mutations is seemingly at odds with the ability of TKIÕs to initially control CML for months to years in the large majority of patients.Nearly all prior studies have used dozens of cycles of PCR amplification to enrich the Abl gene prior to mutation detection. PCR amplification introduces thousands of errors throughout the gene, which makes accurate identification of mutations challenging. Methods of mutation detection such as next-generation sequencing (NGS) are also error prone, with a background error rate near 1%. These high rates of background mutation render accurate detection of minority variants difficult or impossible.We have developed an alternate DNA mutation detection method, termed Duplex Sequencing (Schmitt MW et al, Nature Methods 2015;12:423-425), which improves on the accuracy of DNA sequencing by >100,000 fold. In Duplex Sequencing, the two strands of single DNA molecules are individually tagged and sequenced. True mutations are present at the same position in both strands and are complementary, whereas artifacts arising from amplification or sequencing errors are seen in only one strand and are not scored. We have additionally developed methods for >1,000,000 fold enrichment of the Abl gene from human cells. This enrichment protocol allows for unbiased detection of all possible mutations throughout the Abl gene, with an accuracy exceeding 99.9999%.We applied Duplex Sequencing to 18 patients with newly diagnosed chronic phase CML (CP-CML). We sequenced the active site exons of Abl from tens of thousands of individual CML genomes; no sub-clonal resistance mutations were seen in any patient. We demonstrate that prior reports indicating frequent resistance mutations at the time of CML diagnosis may be attributable to artifactual mutations introduced by reverse transcription and PCR amplification.We are now studying patients from the PACE trial (Cortes JE et al. N Engl J Med. 2013;369:1783-1796); these patients were heavily pre-treated, with the majority having received 3 or more prior TKIÕs. We identified 29 patients from the trial with a treatment-emergent mutation not detectable at baseline by conventional methods (NGS or Sanger), and have performed Duplex Sequencing on 9 of these patients to date. In contrast to treatment-naïve patients, we find that these heavily pre-treated patients commonly harbor multiple co-existing resistant sub-clones, most of which fall below the detection limit of conventional methods but are readily detected by Duplex Sequencing. In addition, in 44% of patients, mutations that emerged during ponatinib treatment were found as rare sub-clones at baseline (average detection limit of 1 in 11,412 cells), indicating that the mutant sub-clones pre-existed prior to ponatinib therapy. We are now sequencing the remainder of the cohort, and are increasing our detection limit through interrogation of a larger number of cells per patient.Our results indicate the feasibility of detecting sub-clonal resistance mutations at the time of initiation of next-line TKI therapy in order to guide treatment, and argue that high-sensitivity methods for mutation detection are required to optimally stratify patients to the most appropriate TKI. Moreover, our approach can detect sub-clonal mutations in any gene, and could be broadly applicable for identification of sub-clonal drug resistance mutations relevant to other targeted therapies. [Display omitted] DisclosuresPritchard:ARIAD: Employment, Equity Ownership. Hodgson:ARIAD Pharmaceuticals: Employment, Equity Ownership. Rivera:ARIAD: Employment, Equity Ownership.

Second Malignancies Following Treatment of Chronic Myeloid Leukemia in the Tyrosine Kinase Inhibitor Era

Background: Since continuous treatment with tyrosine kinase inhibitors (TKIs) has dramatically improved the survival of patients with chronic myeloid leukemia (CML), it is of interest to examine the possible risk of long-term adverse events. Previous studies have presented conflicting results regarding risk of second malignancies. Our aim was to examine the development of second malignancies (except acute myeloid or lymphoblastic leukemia, myelodysplastic syndromes or non-melanoma skin cancer) in CML chronic phase patients diagnosed after the introduction of TKI treatment.Materials and methods: We studied the development of second malignancies in 868 patients diagnosed with CML in chronic phase 2002 to 2011 using the Swedish CML register, cross-linked to the Swedish Cancer register. Each patient was followed from the time of CML diagnosis until death from any cause, date of allogeneic hematopoietic stem cell transplantation (SCT) or end of study on December 31, 2011, whichever came first. SCT was used as an endpoint because of the well established increased risk of second malignancies after this procedure. Standardized Incidence Ratios (SIR) were calculated to assess the risk of a second malignancy by dividing the number of observed second malignancies with the number of expected malignancies in the Swedish population, using data from the Swedish Cancer Register. The expected numbers of malignancies were determined by dividing the CML population according to 5-year age groups, sex, region of residence (6 regions) and calendar year. The number of person-years in each stratum was multiplied with the incidence of malignancies or deaths found in the corresponding strata in the general population.Results: With a median follow-up of 3.7 (range 0-9.9) years, 65 (7.5%) patients developed 75 second cancers (non-hematologic), 49 of these of invasive type. Compared to expected rates in the background population matched by age, sex, region of residence (6 regions) and calendar year, the risk of second malignancies was significantly higher in the CML cohort, with a Standardized Incidence Ratio (SIR) of 1.5 (95 % CI 1.13-1.99). SIR before and after the second year following diagnosis of CML was 1.6 (95 % CI 1.004-2.38) and 1.5 (95 % CI 0.98-2.11), respectively. Looking at CML subpopulations, the increased risk of developing a second malignancy reached statistical significance for females (SIR: 1.8; 95 % CI 1.18-1.99), but not for males (SIR: 1.3; 95 % CI 0.85-1.91), and for patients above 60 years of age at diagnosis (SIR: 1.5; 95 % CI 1.05–1.96). Assessment of risk by cancer type was hampered by small numbers. However, the data at hand indicate an increased risk for gastrointestinal cancer (SIR: 3.0; 95 % CI 1.60-5.16), as well as nose and throat cancer (SIR: 37.1; 95 % CI 7.46-108.40), table 1.Conclusions: Utilizing large, population-based registries with data accumulated during the TKI era, our results indicate that CML patients, compared to the normal control population, are at an 50% increased risk of developing a second malignancy. Similar SIR before and after the second year following the diagnosis of CML may indicate that these findings are linked to the CML disease itself, rather than to the TKI treatment. Further studies and longer follow-up seem however warranted. Physicians caring for CML patients should be aware of signs and symptoms of other malignancies in this patient population.Table 1Standardized Incidence Ratios for second malignancies (excluding cases of non-melanoma skin cancer, AML, ALL and MDS) among 868 Swedish CML patients diagnosed between 2002 and 2011. Total follow up time 3293 person-years (median 3.7 years).VariableObservedExpectedSIR (Observed/Expected)95 % CI forSIROverall52341.51.13–1.99Men26201.30.85–1.91Women26141.81.18–2.66Age <60 years1051.90.89–3.42Age ³ 60 years42281.51.05–1.96Second cancer typeProstate1481.80.96–2.94Gastrointestinal1343.01.60–5.16Gynecological413.60.98–9.30Nose and Throat30,137.17.46-108.40Lung22,70.70.08-2.67Breast44,20.980.26-2.45 DisclosuresBjörkholm:Novartis: Research Funding; Shire: Research Funding; Merck: Research Funding; Amgen: Honoraria, Research Funding; Pfizer: Research Funding; Bristol-Myers Squibb: Honoraria; Celgene: Honoraria; Akinon: Honoraria; Nordic Nanovector: Honoraria. Richter:Ariad: Honoraria; Bristol-Myers Squibb: Honoraria; Novartis: Honoraria. Själander:Novartis: Honoraria.

Outcome of Patients (pts) with Chronic Myeloid Leukemia (CML) Treated with Tyrosine Kinase Inhibitors (TKI) Who Have a History of Prior Malignancies,

Abstract 3787 Background:The natural history of CML has been irrevocably changed since the advent of TKIs with pts living longer than they ever have. Some patients have a history of previous cancers by the time they are diagnosed with CML. These pts’ long-term prognosis has never been previously described. Aims: To determine the effect of prior malignancy on patient outcome after diagnosis of CML. Methods: The primary objective was to determine outcome of pts with a previous diagnosis of malignancy (PM) vs a group without (nPM). Patients included in clinical trials of TKI as initial therapy for CML in chronic phase from July 2000 to January 2011 were reviewed. Results: Of the 471 CML pts treated with frontline TKIs 47 (10%) had a PM before their CML diagnosis and 5 (1%) pts PM status could not be obtained. The median age of the patients with a PM was 60 (30–84) compared to 46 (15–86) for those with no PM. There were no significant differences in clinical characteristics between PM and nPM patients. The median from diagnosis of a PM and a diagnosis of CML was 69 months (mo) (7 mo to 707 mo). The five most common PMs were: non-melanoma skin cancer in 14 (30%), breast cancer in 10 (21%), melanoma in 5 (11%), colorectal cancer in 5 (11%), and prostate cancer in 5 (11%). “Six pts (13%) had more than one PM and 2 of those 6 had 3 PM before the diagnosis of CML, the other 4 pts had 2 PM. The PMs were treated prior to the diagnosis of CML in the following ways: 17 (36%) pts received chemotherapy for their PM, 17 (36%) received radiotherapy, and 43 (91%) received surgery. At the time of CML diagnosis 3 (6%) pts had active cancer, while the remainder of the pts with a PM were thought to be in remission. Two (4%) pts were on active therapy for their prior cancer diagnosis at the time they started on CML therapy (Tamoxifen for breast cancer in both). After the diagnosis of CML, 6 (13%) pts had a recurrence of their PM including 2 pts with basal cell cancer, and 1 each with melanoma, breast cancer, prostate cancer, and lymphoma. These recurrent malignancies were treated as follows: 3 with radiation, 2 had surgery, and 2 with chemotherapy. Five of these 6 pts continued TKI while receiving therapy for PM. The median time between diagnosis of CML and relapse of PM was 18 months. Median remission of the PM was 151 months. Also, 6 (13%) pts had a new malignancy after CML diagnosis: 2 pts with squamous skin carcinoma, and 1 each with chronic lymphocytic leukemia, papillary thyroid carcinoma, mucoepidermoid carcinoma, and large B-cell lymphoma. Treatments for the new onset malignancy after the diagnosis of CML include: surgery (4), chemotherapy (2), radiation (1), and observation (1). The median time between diagnosis of CML and a new malignancy was 39 months. Six of the 47 pts are deceased: 2 died of their PM, 2 died secondary to treatment complications for their PM, 2 died of cardiovascular issues unrelated to a cancer diagnosis. None died of CML. Initial treatment for CML was imatinib 400mg in 4/47 (9%) PM and 69/419 (16%) nPM, imatinib 800mg in 15/47 (33%) PM and 189/419 (45%) nPM, dasatinib in 11/47 (24%) PM and 78/419 (19%) nPM, and nilotinib in 16/47 (35%) PM, and 83/419(20%) nPM. The outcome of pts with PM and nPM is presented in Table 1. There was no significant different in patient outcome between pts with PM and nPM. Conclusion: Pts with CML who have prior malignancies have the same excellent outcome as patients with no prior malignancies. In the few instances in which concomitant therapy for other malignancies was required during therapy with TKI this could be accomplished with no significant toxicity. Thus, the history of prior malignancy in a patient who develops CML should not affect the decision to treat with TKI.Table 1:PMno PMN=47419Sokal Low (%)26 (57)299 (71)Sokal Int (%)15 (33)93 (22)Sokal High (%)5 (11)27 (6)CCyR %9391MMR%8486CMR%666536mos EFS989036mos OS10099 Disclosures:Cortes:Pfizer Inc: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Novartis: Consultancy, Research Funding.

Increased NK Cells and Decreased CD3+CD8+CD62L+ T Cells in CML Patients Who Sustained Complete Molecular Remission After Discontinuation of Imatinib

Abstract 1697 Background and Aim:Recent study demonstrated that approximately 60% of chronic myeloid leukemia (CML) patients who stopped imatinib therapy (STOP-IM) after a period of stable complete molecular remission (CMR) relapsed molecularly within the next 6 months, whereas nearly all the remaining patients sustained a stable CMR beyond 18 months of follow-up. Study design:To elucidate the immunological diversity of CML patients, we assessed subsets of circulating lymphocytes obtained from 30 CML patients: 16 CML patients who had discontinued imatinib treatment for more than 6 months (STOP-IM), and 14 CML patients who were receiving imatinib with CMR for more than 2 consecutive years. Results:One-way analysis of variance revealed that certain cell fractions of lymphocyte subsets were significantly altered in STOP-IM patients compared with healthy volunteers and CML-CMR patients. We focused on the CD3+CD8+CD62L+ and CD3―CD56+ cell fractions, because other cell fractions, except CD19+CD20+, were not particularly different between STOP-IM and CML-CMR patients. The CD3+CD8+CD62L+ cell fractions in STOP-IM patients tended to down-regulate (P = 0.0658) and the CD3―CD56+ cell fraction increased significantly compared with that in CML-CMR (P = 0.0214). Our observations indicate that some lymphocyte subsets may be affected by imatinib therapy, even in CMR. The differences in subset cell fractions between CML-CMR and STOP-IM patients therefore may have some bearing on discontinuation of imatinib therapy. We were able to determine NK cell activity in 11 STOP-IM patients. This activity ranged from 24% to 69% (normal range, 18%–40%); 7 of the 11 patients had elevated NK cell activity, and a positive correlation was found between NK cell activity and NK cell percentages in the 11 STOP-IM patients. Discussion:We noticed deviation in some fractions of circulating lymphocytes in STOP-IM patients with CML, in comparison with CML patients who were CMR but were still taking imatinib. in STOP-IM patients in our study, an elevated cell fraction was detected only in CD3−CD56+ NK cells, and others were down-regulated. We were able to determine NK cell activity in 11 STOP-IM patients. This activity ranged from 24% to 69% (normal range, 18%–40%); 7 of the 11 patients had elevated NK cell activity, and a positive correlation was found between NK cell activity and NK cell percentages in the 11 STOP-IM patients. Two CMR patients satisfied criteria for both down-regulated CD3+CD8+CD62L+ cells and up-regulated CD3―CD56+ NK cells compared with those of healthy subjects. Conclusion:Our results therefore may aid in the selection of possible candidates for discontinuation of imatinib therapy in patients in CMR. The minimal requirements for discontinuation of imatinib treatment might be CMR duration of more than 2 years and low/intermediate Sokal scores at the time of CML diagnosis. In addition, increasing number of NK cells and decreased CD3+CD8+CD62L+ cell fractions may also be indications that imatinib therapy can be stopped. Disclosures:No relevant conflicts of interest to declare.

Megakaryocytic blast crisis at presentation in a pediatric patient with chronic myeloid leukemia

Patients with chronic myeloid leukemia (CML) infrequently present in blast crisis (BC). While most BC are of myeloid origin, megakaryocytic BC is rare, especially at the time of CML diagnosis. We describe the first pediatric patient presenting with megakaryocytic leukemia and having BCR-ABL1 translocation as the single chromosomal abnormality. Clinical features were more suggestive of CML in megakaryocytic blast crisis than Philadelphia chromosome positive de novo AML. The patient was treated with AML-directed chemotherapy and imatinib mesylate followed by umbilical cord blood stem cell transplantation. The patient was in complete molecular response 16 months after stem cell transplantation.

Significance of Minimal Residual Disease in Patients with Chronic Myeloid Leukemia After Allogeneic Hematopoietic Stem Cell Transplantation.

Abstract 3269Poster Board III-1▪▪This icon denotes an abstract that is clinically relevant.Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a potentially curative treatment for patients (pts) with chronic myeloid leukemia (CML). AlloHSCT is associated with long-term disease-free survival in 40% to 80% pts transplanted in early chronic phase of disease. The probability of relapse for pts transplanted in first chronic phase is 10% to 20% at 5 years, and is even higher (30% – 60%) for pts who received transplant in advanced phases of CML. The significance of minimal residual disease (MRD) in this clinical setting is uncertain. We enrolled 63 consecutive pts with CML who had received an alloHSCT between 1995 and 2007 and had BCR-ABL transcript quantity measured by RQ-PCR method on at least 2 occasions during follow-up in the period starting 6 months after alloHSCT. The reverse transcription was preformed using SuperScriptIII and random hexamers. Quantification of BCR-ABL was performed by RQ-PCR assay according to ‘Europe Against Cancer' protocol. BCR-ABL expression was normalized with endogenous control ABL gene and expressed as a ratio BCR-ABL/ABL. According to the amount of BCR-ABL transcript detected in blood or bone marrow after alloHSCT pts were allocated into 3 categories, including pts with no-detectable or stable very low-level of BCR-ABL transcripts (ratio BCR-ABL/ABL below 0.005%), pts with fluctuating-low level of BCR-ABL transcripts (0.005 – 0.01%) and pts with high-level of BCR-ABL transcripts (0.01 – 0.1%). We didn't find any relationships between different BCR-ABL levels after alloHSCT and clinical parameters at the time of CML diagnosis or transplantation, including Sokal, Hasford and Gratwohl scores. Median time from alloHSCT to molecular relapse (MR) was 38 months (range, 8.5 – 88.5 months). The 3-year progression rate into cytogenetic or hematological relapse of CML since MR was 70%. This progression occurred at a median time of 1.4 months (range, 0 – 3.2 months). We found strong correlation between the levels of BCR-ABL transcripts after alloHSCT and a risk of relapse. The incidence of MR was 0%, 26%, 71% for the low-level, fluctuating-low level and high-level of BCR-ABL transcript (p<.0001), respectively. Similarly the risk of cytogenetic and hematological relapse was 0%, 21%, 43% for these pts (p=.001), respectively. Five-year leukemia-free survival was 100%, 83.9% and 66.7% for the pts with low-level, fluctuating-low level and high-level BCR-ABL transcript (p=.003), respectively. There was no apparent relationship between the level of BCR-ABL transcript and overall survival. We conclude that pts with fluctuating-low and/or high levels of BCR-ABL transcripts are at higher risk of disease progression. Sequential RQ-PCR monitoring coupled with pre-emptive therapy can provide a valid strategy to reduce rates of relapse and development of a more individualized approach to management of pts with CML in major molecular response after alloHSCT. Disclosures:Warzocha:BMS: Consultancy, Honoraria; Celgene: Consultancy; Roche: Honoraria; Pfizer: Honoraria; Amgen: Honoraria.

A myeloproliferative disorder may hide another one

Chronic myeloproliferative disorders (MPDs) are divided into Philadelphia-positive chronic myeloid leukemia (CML) and Philadelphia-negative disorders including polycythemia vera, essential thrombocythemia and idiopathic myelofibrosis (IMF). Concomitance of a CML and another MPD is a rare event. We report here the case of a patient presenting initially with IMF who developed a Philadelphia-positive CML 7 years later. At the time of CML diagnosis, two distinct clones were present, one with a 13q deletion and one with a t(9;22). We raise the problem of a CML developing on an initial IMF, or two MPDs occurring from a common or two different stem cells.

The relationship between telomere length and therapy-associated cytogenetic responses in patients with chronic myeloid leukemia.

Chronic myeloid leukemia (CML) is a clonal disease with specific cytogenetic changes involving the Philadelphia (Ph) translocation. The authors examined the relationship between telomere length (terminal restriction fragment [TRF]) and therapy-associated cytogenetic responses in CML patients. The authors examined the telomere length and telomerase activity in 44 patients with Ph-positive CML in the chronic phase. TRF was determined by Southern blot analysis using the (TTAGGG)4 probe and telomerase activity was assessed by the telomeric repeat amplification protocol and fluorescent-labeled primers. At the time of CML diagnosis, 19 patients had TRFs within the age-matched normal range (mean +/- 2 x standard deviation [SD]) and the remaining 25 patients had TRFs shorter than the age-matched normal range (< mean +/- 2 x SD). Hematologic findings, including leukocyte count, hemoglobin level, platelet count, and percentage of bone marrow blasts at the time of diagnosis did not significantly differ between patients with normal and shortened TRFs; however, those with shortened TRFs had high levels of telomerase activity (P = 0.045). In a group of patients treated with alpha-interferon (n = 32), those with normal TRFs had a significantly lower frequency of blast crises (P = 0.0328), a significantly higher incidence of cytogenetic responses (P = 0.0185), and a favorable prognosis (P < 0.01) compared with those with shortened TRFs. These findings suggest that normal TRFs in a small number of CML patients at the time of diagnosis may have a significant amount of normal stem cells remaining. The authors suggest that normal TRFs at the time of diagnosis indicate a subset of CML patients who may respond favorably to alpha-interferon therapy.