Discontinuation Of Imatinib Therapy Research Articles

Imatinib-induced ulcerative colitis.

Imatinib, a tyrosine kinase inhibitor, is the first-line therapy for patients with KIT mutation in gastrointestinal stromal tumor (GIST). Nausea, vomiting, diarrhea, dyspepsia and abdominal pain are common gastrointestinal adverse reactions of imatinib, but imatinib-induced ulcerative colitis (UC) is rarely reported. We presented a case of UC induced by imatinib in a 56-year-old male patient who experienced this adverse event after 5 years of imatinib 400 mg/d treatment following GIST resection. The patient's diarrhea and bloody stools showed significant improvement following the discontinuation of imatinib therapy and administration of antidiarrheal medications. Then, imatinib was restarted at a daily dosage of 400 mg. UC is a rare adverse event associated with imatinib. Physicians should consider the possibility of UC induced by imatinib when patients present with diarrhea and bloody stool after receiving imatinib treatment. This case offered objective evidence of UC induced by imatinib.

Long-term results of therapy for chronic myeloid leukemia: a 20-year analysis of the use of tyrosine kinase inhibitors in Russia

Introduction. In Russia, within the framework of the GIPAP program, in the period from 2001 to 2007 at the National Medical Research Center for Hematology, imatinib therapy was initiated in 235 patients in the chronic phase of chronic myelogenous leukemia (CML).Aim: to analyze the long-term results of therapy in patients with CML who started imatinib therapy as part of the GIPAP program.Methods. A retrospective analysis of the results of therapy was performed in 235 patients with СР CML, who received imatinib under the GIPAP program from 2001 to 2007 at the National Medical Research Center for Hematology. The protocols for therapy and monitoring of the residual disease of patients at various time intervals were determined by the clinical recommendations relevant at that time in the conditions of real clinical practice and the possibilities of the patient’s region of residence. Overall survival and survival without discontinuation of imatinib therapy, univariate and multivariate analysis of overall survival were performed. The cumulative incidence of responses was calculated. An analysis of response factors, the probability of death from concomitant diseases and death from CML was carried out.Results. The median follow-up of living patients at the time of analysis was 17.3 years (IQR 15.5–18.5). 70 (30 %) patients died, with the median time to death from the start of therapy being 7.8 years (IQR 3.7–13.6). The overall 10-year, 15-year and 20-year survival rates were 82 %, 74 % and 62 %. The cause of death in 43 cases (61%) was the progression of CML to the phase of acceleration or blast crisis and death out of remission for an unspecifi ed cause. 27 (39%) patients died from causes not related to CML. Patient age at initiation of imatinib therapy, length of time from diagnosis to initiation of imatinib therapy, and Sokal and ELTS risk groups at disease onset were identifi ed as signifi cant for survival by univariate analysis. Multivariate analysis showed independent predictive value for overall survival for age at initiation of imatinib therapy, length of illness before imatinib treatment, and ELTS risk group at disease onset. Among patients who died from CML progression, the proportion of patients who did not achieve CCyR for the entire period of therapy before death was 83% (35/42), while among patients who died from concomitant diseases, the proportion of patients without CCyR for the entire period of therapy was 11 % (p < 0.0001). The median duration of imatinib therapy was 11.4 years (0.8–21 years). 40 people died during imatinib therapy, 103 patients are alive and continue therapy with imatinib, 92 patients received at least one second-generation of Tyrosine kinase inhibitors (TKI) (TKI2), of which 62 people are alive and continue treatment with TKI. No more than two lines of TKI therapy were received by 49 (21 %) patients, and three or more lines were prescribed to 43 (18 %) patients. The median duration of therapy after switching to TKI2 was 7.8 years (0.1–15.6 years). Overall 15-year survival after switching to TKI2 was 59 %. On therapy with imatinib, during the entire observation period, complete cytogenetic response (CCyR) was achieved in 171 patients (73 %), another 18 patients (8 %) achieved CCyR for the fi rst time after switching to TKI2. Major (MMR) and deep molecular response (DMR) were achieved with imatinib in 129 (56 %) and 124 (53 %) patients, with TKI2 TKI2 therapy in 38 (16 %) and 33 (14 %) patients, respectively. Multivariate analysis showed an independent predictive value of only the time period from diagnosis to the start of imatinib treatment for achieving molecular responses to TKI therapy.Conclusion. After 20 years of monitoring patients on TKI therapy, we still cannot say that survival in CML is comparable to the survival of normal population. Long-term follow-up confi rms the fact that tumor reduction to at least the level of CCyR is the most signifi cant surrogate marker associated with a reduced risk of death from CML. Timely diagnosis of the disease, rapid initiation of targeted therapy and the fastest possible induction of cytogenetic and molecular responses is a very important mechanism for reducing the risk of resistant course and progression of CML.

Long-term outcomes of patients with Chronic Myeloid Leukemia who commenced treatment with imatinib: a 20-year single-centre experience

We report on long-term outcomes of 267 patients (pts) with chronic myeloid leukemia (CML) treated with imatinib administered as initial therapy. The median follow-up time was 11.4 years. 38 (14.2%) pts attempted to discontinue imatinib therapy after achieving sustained deep molecular response (≥MR4), 15 of them achieved treatment-free remission (TFR). 144 pts (53.9%) have been switched to other TKI during the follow-up period. The estimated OS for 267 pts for 10, 15 and 18 years was 98.8%, 75.6% and 52.1%. According to prognostic scores (Sokal, Euro, ELTS), OS and PFS were significantly better in low-risk pts than in high-risk pts. According to ELTS, low-risk pts have a better chance of achieving MR4 than both intermediate (p = 0.03) and high-risk (p = 0.04) groups. It suggests that a specific ELTS-adapted treatment could help to optimize treatment results. In the study population, imatinib has demonstrated sustained efficacy and an acceptable rate of late toxic effects.

Imatinib Suspension and Validation Study: Results from the Isav Study at 62 Months

Introduction. Imatinib discontinuation in Chronic Myeloid Leukemia (CML) patients (pts) with minimal residual disease is a procedure that allows a treatment free remission in approximately 50% of them. However long term follow-up data are generally missing Here we report an update of the Imatinib Suspension And Validation (ISAV) study at 62 months (mts) of follow-up (FUP).Aims. The ISAV study is aimed at validating the capability of digital PCR (dPCR) to predict relapses after imatinib discontinuation in CML pts with negative Q-RT-PCR results and to evaluate relapse rate, time of recurrence, survival and the impact of imatinib treatment on Quality of Life (QoL).Methods. This study involves 15 sites, 10 in Italy and 1 in each of the following countries: Germany, Spain, The Netherlands, Canada and Israel. CML pts (Chronic or Accelerated Phase) under imatinib therapy since more than 2 years and in complete molecular remission (CMR) were eligible. Patients had to be in CMR for at least 18 mts, with a minimum of 3 Q-RT-PCR performed at their own sites. After discontinuation of imatinib therapy, Q-RT-PCR was performed monthly (mts 1-6), bimonthly for 36 mts and then every 6 months for additional 2 years, to assess the maintenance of the molecular remission. The loss of molecular remission was defined as two consecutive positive Q-RT-PCR tests with at least one BCR-ABL/ABL value above 0.1%. Patients losing molecular remission resumed imatinib treatment at the same dosage used before interruption. Patients' QoL during imatinib discontinuation/resumption was evaluated through the EORTC QLQ-C30 questionnaire.Results. The ISAV study enrolled 112 pts with a median FUP time of 47.6 mts [95% CI: 42.8-53.0]; 36.6% of them completed the study. The 59.3% of pts were male and 37.0% were aged 65 or older; median duration of imatinib treatment was 103.1 mts with median duration of CMR of 25.4 mts before imatinib discontinuation. dPCR results showed that 23.1% of pts were positive and 75.9% negative at the time of discontinuation, with a Negative Predictive Value ratio (dPCR/Q-RT-PCR) of 1.1 [95% CI: 0.99-1.22]. At 62 mts from imatinib discontinuation, 55 pts (50.9%, 95% CI: 41.1-60.7) of the 108 eligible ones relapsed and resumed imatinib with a relapse rate of 51.9% [95%CI: 42.5-61.0]; 70.9% of them relapsed in the first 9 mts. Of the 53 not-relapsed pts, 40 (37.0% of the total) regained Q-RT-PCR positivity without losing MMR. The median time to Q-RT-PCR positivity was 3.2 mts [95% CI: 2.1-4.6] in the relapsed pts and 4.8 mts [95% CI: 2.9-7.8] in pts who developed only PCR positivity. In this latter group 2 pts experienced late relapses, at 30.6 and 45.5 mts respectively. A loss of CCyR occurred in 13 pts (34.2% of those tested): 10/13 CCyR losses were recovered, the remaining 3 were not be assessed for response. No case of CML progression or resistance to imatinib was observed. After the resumption of imatinib the median time to MMR/CMR was 1.8 [95% CI: 1.1-2.1] mts. One patient, who relapsed, successfully managed a second attempt at discontinuation. No significant correlation between relapse and previous duration of imatinib treatment, use of interferon, time to CCyR, Sokal score or duration of CMR was identified, while an inverse relationship between pts age and risk of relapse was evident. Moreover, age and dPCR results together can predict the risk of relapse: pts with less than 45 years and with a positive dPCR had the highest risk of relapse (100%) as opposed to pts ≥45 years and with negative dPCR (36.1%). The analysis of QoL evidenced a statistically significant improvement in the general well-being and symptoms scales at 1 month after imatinib discontinuation and in particular nausea, diarrhea and fatigue (p<0.01). An inverse and transient trend toward increased pain emerged at mts 1 and 3.Conclusions. At 62 mts from the beginning of the study, with a median FUP of 47.6 mts, 50.9% of pts relapsed; the majority of relapses developed in the first 9 mts after imatinib discontinuation however late relapses also occurred, up to the 4th year. Therefore pts who discontinue imatinib should be monitored for a long period of time, especially if they showed positive PCR values after imatinib discontinuation. Age <45 years and dPCR positivity are significantly associated with relapses. QoL analysis showed a significant decrease in symptoms after imatinib discontinuation. Funded by Regione Lombardia. Disclosuresle Coutre:Novartis: Honoraria, Research Funding; BMS: Honoraria; Pfizer: Honoraria; Incyte: Honoraria; ARIAD: Honoraria. Abruzzese:BMS: Consultancy; Pfizer: Consultancy; Novartis: Consultancy; Incyte: Consultancy. Assouline:Novartis Canada Inc.: Honoraria; Bristol Myer Squibb: Speakers Bureau; Pfizer: Speakers Bureau; Paladin: Speakers Bureau; Janssen: Honoraria. Stagno:Incyte: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria. Iurlo:Pfizer: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria. Gambacorti-Passerini:Pfizer: Consultancy, Honoraria, Research Funding; BMS: Consultancy.

Genotypes of the Gene Encoding the Membrane Transporter SLC22A4 Are Associated with Molecular Relapse-Free Survival after Discontinuation of Imatinib Therapy in Patients with Chronic Myeloid Leukemia

Introduction: The single nucleotide polymorphism (SNP) rs460089 (G/C) located in the promotor of SLC22A4 (transporter hOCTN1) was identified as a prognostic factor for the outcome of chronic myeloid leukaemia patients treated with imatinib first line (Jaruskova et al. JECCR 2017). Patients with GC genotype had significantly higher probability of achievement of sustained major molecular response (MMR, BCR-ABL≤0.1% IS) as compared with patients with GG. We investigated differences in the outcome after imatinib cessation in EURO-SKI patients according to the genotypes of the SNP rs460089. Methods: DNA analysis was performed by TaqMan SNP genotyping assay using StepOnePlus RQ-PCR System (Thermofisher Scientific). In addition to the inclusion criteria defined for prognostic analysis in Saussele et al. (Lancet Oncology 2018), all patients with interferon pre-treatment were excluded. Data on sex, duration of IM treatment, of deep molecular response and age at time of imatinib discontinuation as well as molecular status at 6 months thereafter were available for 178 patients. Logistic regression was used to investigate factors affecting MMR maintenance at 6 months. Level of significance was 0.05. Results: Of 178 patients, 106 (60%) maintained MMR 6 months after imatinib stop. GC genotype was identified in 64 patients, GG in 96 and CC in 18. Most beneficial for MMR maintenance was genotype GC (72%, 95% confidence interval (CI): 60-82%), followed by CC (61%, CI: 38-80%) and GG (51%, CI: 41-61%). Overall, the SNP rs460089 was associated with MMR maintenance (p=0.0335) with a significantly higher odds ratio (OR) for maintenance for GC genotype vs. GG (2.451, CI: 1.247-4.819, p=0.0093) but not for CC vs. GG (1.507, CI: 0.539-4.216, p=0.4343). Only duration of TKI treatment was significant (OR: 1.157, CI: 1.014-1.319, p=0.0303) when added to genotypes in multiple regression. The OR of GC vs. GG was slightly modified to 2.311 (1.164-4.588, p=0.0166). Conclusions: Based on observed data we suppose that the GC genotype of the SNP rs460089 is associated with sufficient intracellular concentration of imatinib allowing more efficient targeting of CML cells during the treatment. This resulted in a higher proportion of patients who sustained MMR after imatinib stop as compared with patients with GG. Longer duration of imatinib treatment increased the probability of MMR maintenance after imatinib cessation also in patients with GG. The frequency of CC was low and outcome in between GC and GG. The SNP rs460089 may provide an independent prognostic factor for molecular response maintenance after imatinib cessation. Supported by MZCR 00023736. Disclosures Machova: Novartis: Consultancy; BMS: Consultancy, Research Funding; Incyte: Consultancy. Fabarius:Novartis: Research Funding. Brümmendorf:Pfizer: Consultancy, Research Funding; University Hospital of the RWTH Aachen: Employment; Merck: Consultancy; Ariad: Consultancy; Novartis: Consultancy, Research Funding; Janssen: Consultancy. Burchert:Novartis: Research Funding. Mustjoki:BMS: Honoraria, Research Funding; Novartis: Research Funding; Pfizer: Research Funding. Mayer:AOP Orphan Pharmaceuticals AG: Research Funding. Žáčková:Bristol Myers Squibb: Consultancy; Angelini: Consultancy; Incyte: Consultancy; Novartis: Consultancy. Panayiotidis:Bayer: Other: Support of clinical trial. Richter:Novartis: Consultancy; Pfizer: Consultancy, Research Funding. Hjorth-Hansen:BMS: Research Funding; Pfizer: Consultancy, Research Funding; Austrian Orphan Pharma: Consultancy, Research Funding. Saussele:Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Pfizer: Honoraria; Incyte: Honoraria, Research Funding.

Imatinib Suspension and Validation (ISAV) Study: Final Results at 79 Months

Introduction. It is known that imatinib can be safely discontinued in patients (pts) with Chronic Myeloid Leukemia (CML) with minimal residual disease. Here we report an update of the Imatinib Suspension And Validation (ISAV) study at 79 months (mts) from study initiation to provide long term follow up data.Aims. The ISAV study aims to validate the capability of digital PCR (dPCR) to predict relapses after imatinib discontinuation in CML pts with negative Q-RT-PCR and to evaluate relapse rate, time to recurrence, survival and the impact of imatinib treatment on Quality of Life (QoL).Methods. This study involves 15 sites, 10 in Italy and 1 in each of the following countries: Germany, Spain, The Netherlands, Canada and Israel. CML pts (chronic or accelerated phase) treated with imatinib for more than 2 years and in complete molecular remission (CMR) were eligible. Patients had to be in CMR for at least 18 mts, with a minimum of 3 Q-RT-PCR performed at their own sites. After discontinuation of imatinib therapy, Q-RT-PCR was performed monthly (mts 1-6), bimonthly for 36 mts and then every 6 mts for additional 2 years, to assess the maintenance of the molecular remission. The loss of molecular remission was defined as two consecutive positive Q-RT-PCR tests with at least one BCR-ABL/ABL value above 0.1%. Patients losing molecular remission resumed imatinib treatment at the same dosage used before interruption. dPCR was performed at screening and at 36 mts for those pts who were still in remission. Patients' QoL during imatinib discontinuation/resumption was evaluated through the EORTC QLQ-C30 questionnaire.Results. The ISAV study enrolled 112 pts with a median follow-up time of 60.0 mts [95% CI: 59.6-60.6] for pts who do not relapsed; 66.1% of them completed the study as per protocol. The 58.9% of pts were male and 37.4% were aged 65 or older; median duration of imatinib treatment was 103.2 mts with median duration of CMR of 25.6 mts before imatinib discontinuation. At 79 mts from imatinib discontinuation, 56 pts of the 107 eligible ones relapsed and resumed imatinib with a relapse rate of 52.3% [95%CI: 20.4-32.6]; 69.6% of them relapsed in the first 9 mts. Of the 52 not-relapsed pts, 40 (76.9%) regained Q-RT-PCR positivity without losing MMR. In this latter group 2 pts experienced late relapses, at 30.6 and 45.5 mts respectively. A loss of CCyR occurred in 13 pts (23.6%): 10/13 CCyR losses were recovered, the remaining 3 were not assessed for response. No case of CML progression or resistance to imatinib was observed. After the resumption of imatinib the median time to MMR/CMR was 1.8 [95% CI: 1.0-2.0] mts. No significant correlation between relapse and previous duration of imatinib treatment, use of interferon, time to CCyR, Sokal score or duration of CMR was identified, while an inverse relationship between pts age and risk of relapse was evident. dPCR results before imatinib discontinuation showed that 23.4% of pts were positive and 76.6% negative at the time of discontinuation, with a Negative Predictive Value ratio (dPCR/Q-RT-PCR) of 1.1 [95%CI: 0.99-1.22]. At 36 mts from imatinib discontinuation 80.4% [95%CI: 30.6-50.4] of the pts tested were positive in dPCR. Moreover, the results of dPCR performed at imatinib discontinuation and age together can predict the risk of relapse: pts with less than 45 years and with a positive dPCR had the highest risk of relapse (100%) as opposed to pts ≥45 years and with negative dPCR (36.1%). The analysis of QoL evidenced a statistically significant improvement in the general well-being and symptoms scales at 1 month after imatinib discontinuation, particularly with regard to nausea, diarrhea, fatigue and insomnia (p<0.05). An inverse and transient trend toward increased pain emerged at mts 1 and 3.Conclusions. At 79 mts from the beginning of the study, 52.3% of pts relapsed, with 24% loosing CCyR. The majority of relapses occurred in the first 9 mts after discontinuation however late relapses were also observed, up to the 4th year. Therefore, pts who discontinue imatinib should be monitored for a long period of time, especially if they show positive PCR values after discontinuation. All relapsed pts including those who lost CCyR regained their original response after restarting TKI. Age <45 years and dPCR positivity are significantly associated with relapses. QoL analysis showed a significant decrease in symptoms after imatinib discontinuation. Funded by Regione Lombardia. Disclosuresle Coutre:Pfizer: Honoraria; Incyte: Honoraria; BMS: Honoraria; Novartis: Honoraria. Abruzzese:BMS: Consultancy; Novartis: Consultancy; Pfizer: Consultancy; Ariad: Consultancy. Assouline:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Research Funding, Speakers Bureau; Pfizer: Honoraria, Research Funding, Speakers Bureau; BMS: Honoraria, Research Funding, Speakers Bureau; Novartis: Research Funding. Kim:Pfizer: Research Funding; BMS: Research Funding; Ilyang: Research Funding; Novartis: Research Funding. Gambacorti-Passerini:Pfizer: Consultancy, Honoraria, Research Funding; BMS: Consultancy.

Expert Opinion on the Treatment of Refractory Chronic Phase Chronic Myeloid Leukaemia

The development and clinical availability of second-generation tyrosine kinase inhibitors (TKIs) for the treatment of patients who discontinue imatinib therapy has further improved the outlook for patients with chronic phase chronic myeloid leukaemia (CP-CML). There is, however, uncertainty surrounding how best to treat patients after failing second-generation TKIs. A three-section questionnaire was devised by chronic myeloid leukaemia experts to address questions surrounding this issue. Responses were received from 14 out of 34 experts (41.2%). Generally, a reasonable consensus was found among the responses for most issues. There was a complete consensus that ponatinib was suitable for all patients carrying the T315I mutation regardless of the molecular response to prior treatment. There was also complete consensus that allografting is appropriate in any patient who has had blast crises and is back in a second chronic phase. More recommendations for third-line treatment of CP-CML patients are necessary.

Pattern of chronic myeloid leukemia in the imatinib era in a Sub-Saharan African setting

Chronic myeloid leukemia (CML) is an orphan disease in Africa because of the inaccessibility to specific treatment and the high cost of diagnosis and monitoring patients. The aim of this study was to report CML treatment response in a developing country in the tyrosine kinase inhibitor era. We conducted a longitudinal study of our cohort of CML patients. Socio-demographic, diagnosis, therapeutic, and treatment response parameters were studied. Sokal score, disease phase at diagnosis, delay from diagnosis to treatment, and treatment response were analyzed for their impact on survival. Fifty-five patients with a diagnosis of CML and who received treatment with imatinib for a minimum of 3months were included in this study. Median follow-up was 170 patient-years. The sex ratio (M/F) was 1.62 and median age at diagnosis was 42years. At diagnosis, 85.5% of the patients were in chronic phase (CP), 12.7% in accelerated phase (AP), and 1.8% in blast crisis (BC). Sokal risk score distribution was as follows: low risk 29.8%, intermediate risk 38.3%, and high risk 31.9%. Median time from first symptoms to first medical visit was 6.2months and median time from first medical visit to cytogenetic and or molecular confirmation was 12.4months. Mean delay time from first medical visit to imatinib initiation was 12.5months (95% CI 6.3-18.7). The complete hematologic response (CHR) at 3months, the major cytogenetic response (MCR) at 12months, and the major molecular response (MMR) at 24months were respectively 82.4, 75, and 25%. The 2-year overall survival rate was 81%. Advanced phase at the diagnosis, discontinuation of imatinib therapy over 15% of the time, lack of CHR at 3months, lack of MCR at 12months, and progression of the disease during imatinib therapy were associated with a risk of death (p ≤ 0.05). Our data confirm the improved prognosis of CML treated with imatinib in the setting of a developing country. However, response rates are lower than in developed countries, and additional efforts should be made to facilitate early diagnosis and improve access to TKI, treatment compliance, and regular molecular monitoring of patients.

Musculoskeletal pain after stopping tyrosine kinase inhibitor in patients with chronic myeloid leukemia: a questionnaire survey.

We conducted a questionnaire survey to assess the state of patients with CML after discontinuation of TKI therapy. Nine of 27 patients developed musculoskeletal pain after TKI discontinuation. One had discontinued nilotinib and eight had discontinued imatinib therapy. Median time to symptom development after discontinuation was 2 weeks. Four experienced grade 3 symptoms as per the CTCAE ver. 4.0. One had pain persisting over a period of 21 months. There was a significant difference between patients with and without symptoms as regards female gender and the probability of persistent MMR. Awareness of this withdrawal syndrome after TKI discontinuation is imperative.

Imatinib Suspension and Validation (ISAV) Study: Results at 24 Months

▪Introduction. A substantial proportion of patients (pts) affected by Chronic Myeloid Leukemia (CML) achieve complete negativity in Q-RT-PCR. In this situation, as already demonstrated in other STOP trials, it is possible to safely discontinue imatinib treatment but it is still not clear how to discriminate subjects who will relapse. In fact even undetectable BCR-ABL may not equate to eradication of the disease because of the sensitivity of Q-RT-PCR. A new diagnostic method, the digital-PCR (dPCR), able to detect 1 BCR-ABL+ cell out of 107 cells, has been developed. Therefore, dPCR by assessing the presence of minimal residual disease with higher sensitivity, could potentially identify pts in whom CML has been eradicated.Aims. The ISAV study is aimed at validating the capability of dPCR to predict relapses after imatinib discontinuation in CML pts with negative Q-RT-PCR results and to evaluate relapse rate and timing of recurrence, survival and the impact of imatinib treatment on Quality of Life (QoL).Methods. This study involves 15 sites, 10 in Italy and 1 in each of the following countries: Germany, Spain, The Netherlands, Canada and Israel. CML pts (Chronic or Accelerated Phase) under imatinib therapy since more than 2 years and in complete molecular remission (CMR) were eligible. Patients had to be in CMR for at least 18 months (mts), with a minimum of 3 Q-RT-PCR performed at their own sites. After signing the informed consent, blood samples were obtained for dPCR and the pts discontinued imatinib therapy. Standard Q-RT-PCR is performed monthly (mts 1-6) and then bimonthly for 36 mts to assess the maintenance of the molecular remission. The loss of molecular remission is defined as two consecutive positive Q-RT-PCR tests with at least one BCR-ABL/ABL value above 0.1%. Patients losing molecular remission resume imatinib treatment at the same dosage used before interruption. Patients' QoL during imatinib discontinuation/resumption is evaluated through the EORTC QLQ-C30 questionnaire.Results. The study enrolled 112 pts with a median follow-up (FUP) time of 28.0 mts [95% CI: 25.5-30.1]. The 59.3% of pts were male and 37.0% were aged 65 or older; median duration of imatinib treatment was 103.1 mts with median duration of CMR of 25.7 mts before imatinib discontinuation. The cumulative probability of survival is 97.8% [95% CI: 91.4-99.5]. dPCR results showed that 23.1% of pts were positive and 75.9% negative, with a significant Negative Predictive Value ratio (dPCR/Q-RT-PCR) of 1.112 [95% CI: 1.009-1.225]. At 24 mts from imatinib discontinuation, 53 pts (49.1%, 95% CI: 39.3-58.9) of the 108 eligible pts relapsed and resumed imatinib; 73.6% of them relapsed in the first 9 mts and the last relapse occurred 21.8 mts after imatinib discontinuation. A loss of CCyR occurred in 13 pts (34.2% of those tested): 10/13 CCyR losses were recovered, the remaining 3 were not assessed for response. No case of CML progression or resistance to imatinib was observed. After the resumption of imatinib the median time to MMR/CMR was 1.9 [95% CI: 1.2-2.4] mts. Of the 55 not-relapsed pts, 42 (38.9% of the total) regained Q-RT-PCR positivity but never lost MMR. The median time to Q-RT-PCR positivity was 2.9 mts [95% CI: 2.0-3.1] in the relapsed pts and 4.5 mts [95% CI: 2.9-6.9] in pts who developed only PCR positivity. No significant correlation between relapse and previous duration of imatinib treatment, use of interferon, time to CCyR, Sokal score or duration of CMR was identified, while an inverse relationship between pts age and risk of relapse is evident. Moreover, age and dPCR results together can predict the risk of relapse: pts with less than 45 years and with a positive dPCR had the highest risk of relapse (100%) as opposed to pts ≥ 45 years and with negative dPCR (36.1%). The analysis of QoL evidenced a statistically significant improvement in the general well-being and symptoms scales at 1 month after imatinib discontinuation and in particular nausea, diarrhea and fatigue (p<0.01). An inverse and transient trend toward increased pain emerged at mts 1 and 3.Conclusions. At 45 mts from the beginning of the study, with a median FUP of 28.0 mts, 49.1% of pts relapsed; the majority of relapses developed in the first 9 mts after imatinib discontinuation. Age < 45 years and dPCR positivity are significantly associated with relapses. QoL analysis showed a significant decrease in symptoms after imatinib discontinuation. Funded by Regione Lombardia. DisclosuresAbruzzese:BMS, Novartis, Pfizer, Ariad: Consultancy. Assouline:BMS: Consultancy; Pfizer: Consultancy; Novartis: Consultancy. D'Emilio:Celgene: Research Funding. Dong-Wook:ll-Yang: Consultancy, Honoraria, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis Pharmaceuticals: Consultancy, Honoraria, Research Funding, Speakers Bureau.

Mature, Adaptive-like CD56DIM NK Cells in Chronic Myeloid Leukemia Patients in Treatment Free Remission

▪Background: Tyrosine kinase inhibitors (TKIs) have significantly improved the treatment of CML. Even though TKI treatment is generally not considered curative, recent studies have shown that nearly half of CML patients who have achieve good and durable responses are able to stop the TKI treatment. However, patients who have successfully discontinued TKI treatment still have residual disease. We hypothesized that the immune system plays a role in treatment free remission (TFR), and our preliminary results in the EURO-SKI trial showed that patients who relapse early after imatinib discontinuation have decreased numbers and frequencies of NK cells. In EURO-SKI trial relapse was defined as the loss of major molecular response (MMR). We now aimed to analyze in more detail the phenotype and function of the NK cells in order to understand their role in TFR.Methods: Lymphocyte subclass analysis (the number of NK-, T- and B-cells) was performed at the time of therapy discontinuation and 1 month after the imatinib discontinuation in patients participating in the EURO-SKI stopping trial in the Nordic countries (n=105, results are presented from patients who have reached 6 months follow-up). More detailed immune phenotype and functional assays (NK-cell degranulation and secretion of Th1 type of cytokines IFN-γ/TNF-α) were analyzed from a proportion of patients (n=31).Results: Imatinib treated patients remaining in remission for 6 months (non-relapsing, n=48, median age 60,5 years) displayed an increased amount of NK cells at the time of drug discontinuation (18.6% vs. 11.0%, p=0.02, NK-cell count 0.25 x109 cells/L vs. 0.184 x109 cells/L m, p=0.059) compared to patients who relapsed early (before 5 months, n=29, median age 60,5 years). Furthermore, the NK cell frequency in non-relapsing patients was even higher than in healthy controls (11.5%, n=48, p=0.001). T and B cell counts and frequencies showed no differences between the groups.Detailed analysis of the NK cell compartment displayed a more mature phenotype for the NK cells in non-relapsing patients. Larger frequencies of NK cells from early relapsing patients was CD56bright compared to non-relapsing patients (4.8% vs. 2.7% of CD56 NK cells, p=0.04). Furthermore, patients who had higher frequencies of CD56bright NK cells than median had decreased TFR at 6 months (42%) compared to patients with lower frequency (70%, p=0.01). In addition, there was a trend towards more CD57pos (78% (n=21) vs. 66% (n=10), p=0.09) CD56dim NK cells in non-relapsing patients.To further study the mature NK cells in non-relapsing patients, recently identified markers (FceRgneg, PLZFneg, SYKneg, EAT-2neg) for adaptive NK cells were analyzed. Interestingly, there was a trend that non-relapsing patients had higher frequencies of adaptive-like NK cells. For example, non-relapsing patients had more CD56dim NK cells that had down regulated EAT-2 (2.8% (n=6) vs. 1.3% (n=5) of lymphocytes, p=0.03) and more CD56dim NK cells expressing NKG2D (11.2% vs. 2.6% of lymphocytes, p=0.02) and NKp46 (13.6% vs. 3.9% of lymphocytes, p=0.05). Moreover, after imatinib discontinuation the expression of transcription factor Eomes increased in the CD56dim NK cells of the early relapsing group (baseline MFI 2045 vs. 1 month 3480, p=0.06), while in non-relapsing group it seemed to even decrease (baseline MFI 2273 vs. 1 month 1980, p=0.13) pointing towards an adaptive phenotype.No significant differences between the groups were observed when degranulation against K562 cell line was studied. However, CD16neg NK cells from non-relapsing patients responded to K562 stimulation by secreting more TNFα/IFNγ compared to the early relapsing patients (21% vs. 13% of CD56pos CD16neg NK cells, p=0.01). Furthermore, patients whose CD16neg NK cells had higher than median TNFα/IFNγ secretion when stimulated with K562 cells showed an increased TFR at 6 months (78%) compared to patients who had lower TNFα/IFNγ secretion than median (37%, p=0.005).Conclusions: CML patients who successfully discontinued imatinib therapy displayed a higher number and frequency of peripheral blood mature, adaptive-like NK cells capable of secreting cytokines TNFα/IFNγ relative to relapsing patients. How such NK cells may contribute to maintenance of treatment free remission is still unknown. Nonetheless, our results warrant further clinical studies with NK-cell modulating agents. DisclosuresMuller:Novartis: Honoraria, Other: Consulting or Advisory Role, Research Funding; ARIAD Pharmaceuticals Inc.: Honoraria, Other: Consulting & Advisory Role, Research Funding; BMS: Honoraria, Other: Consulting or Advisory Role, Research Funding. Hjorth-Hansen:Novartis: Honoraria; Ariad: Honoraria; Bristol-Myers Squibb: Research Funding; Pfizer: Honoraria, Research Funding. Saussele:Pfizer: Honoraria, Other: Travel grant; BMS: Honoraria, Other: Travel grant, Research Funding; Novartis Pharma: Honoraria, Other: Travel grant, Research Funding; ARIAD: Honoraria. Mahon:ARIAD: Consultancy; Novartis: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Pfizer: Consultancy. Porkka:Bristol-Myers Squibb: Honoraria; Celgene: Honoraria; Novartis: Honoraria; Pfizer: Honoraria. Richter:Ariad: Honoraria; Bristol-Myers Squibb: Honoraria; Novartis: Honoraria. Mustjoki:the Finnish Cancer Societies: Research Funding; Pfizer: Honoraria, Research Funding; Academy of Finland: Research Funding; Sigrid Juselius Foundation: Research Funding; Finnish Cancer Institute: Research Funding; Signe and Ane Gyllenberg Foundation: Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Research Funding.

Nonhematologic toxicity of imatinib mesylate in pediatric patients with chronic myelogenous leukemia: a predominance of musculoskeletal pain.

Therapy with the tyrosine kinase inhibitor imatinib mesylate has become standard initial treatment for adult and pediatric patients with chronic myelogenous leukemia. Long-term follow-up data are now available in the adult population, and the toxicity profile of imatinib mesylate among adults has been extensively studied and reported. Despite its increasing use in the pediatric population, there are limited data regarding adverse event profiles of imatinib mesylate in children, and few reports exist in the literature focusing on nonhematologic toxicity in this population. We reviewed our institutional experience with imatinib therapy for chronic myelogenous leukemia over an 8-year period of time. Nine pediatric patients began therapy with imatinib mesylate and were included in this review. We reviewed the occurrence of nonhematologic toxicity in this cohort and the impact of that toxicity on continuation of therapy. Eight patients experienced nonhematologic toxicity, including nausea/vomiting (44.4%) and musculoskeletal pain (88.9%). Three patients (33.3%) required discontinuation of imatinib therapy due to grade 3/4 musculoskeletal pain, a rate that is significantly higher than that seen in the adult population. As imatinib therapy becomes increasingly widespread in the treatment of pediatric malignancies, there may be different patterns of clinically significant nonhematologic toxicity, including higher grade musculoskeletal pain.

Imatinib Mesylate-Induced Erythema Multiforme: Recurrence after Rechallenge with 200 mg/day Imatinib.

Dear Editor: Imatinib mesylate (Gleevec; Novartis AG, Basel, Switzerland), a selective tyrosine receptor kinase inhibitor, is increasingly used for treating chronic myeloid leukemia, Philadelphia chromosome-positive acute lymphoblastic leukemia, and high-grade gastrointestinal stromal tumors (GISTs)1. Several cases of cutaneous reactions after imatinib use have been reported1. We report a case of EM after imatinib administration for the treatment of a GIST. A 66-year-old woman was referred for pruritus from the department of oncology. She received a diagnosis of a GIST, for which she received adjuvant imatinib therapy after gastric wedge resection. She noticed a pruritic rash on her trunk after 5 weeks of 400 mg/day imatinib therapy. Physical examination revealed generalized variable-sized erythematous wheal-like patches with some targetoid lesions on the trunk, face, and extremities (Fig. 1). Immunoglobulin (Ig) G and IgM antibodies to the herpes simplex virus were not detected. A skin biopsy from the trunk revealed vacuolar degeneration, tagging of lymphocytes along the dermal-epidermal junction, and perivascular lymphocytic and some eosinophilic infiltrations in the upper dermis (Fig. 2A). Some dyskeratotic and necrotic keratinocytes were obvious in the epidermis (Fig. 2B); therefore, EM was diagnosed. As imatinib was the only medication administered to the patient, it was considered the most probable cause. Imatinib was discontinued, and oral steroid and antihistamine were prescribed. For 2 weeks, 30 mg/day steroid, tapered to 5 mg/day, was administered. One month after the discontinuation of imatinib therapy, the rash was fully cured. Imatinib treatment was restarted at a lower dose of 100 mg/day without steroids; no skin lesion developed for 2 months. However, when the dose was increased to 200 mg/day without oral steroids, a similar rash developed. The patient could continue imatinib therapy with a gradual dose escalation from 100 to 200 mg/day with concomitant 5 mg/day oral steroids. No additional skin lesions were detected during 5 months of follow-up. Fig. 1 Clinical manifestations of the patient. (A) Generalized erythematous variable-sized wheal-like patches on the trunk. (B) Several lesions showing the typical targetoid appearance. Fig. 2 Histopathological findings of the lesion. (A) Vacuolar degeneration, tagging of lymphocytes along the dermal-epidermal junction, and perivascular lymphocytic and a few eosinophilic infiltrations in the upper dermis (H&E, ×200). (B) Spongiosis ... It is estimated that approximately 7%~21% of patients treated with imatinib experience variable degrees of skin eruptions2. There are a few reports of imatinib-induced EM. Park et al.3 reviewed patients with cutaneous eruptions after imatinib therapy, and 2 of 10 patients (20%) had EM-like drug eruptions. The cutaneous adverse effects of imatinib are dose dependent and seemingly related to a pharmacological effect of the drug1,2. The most common skin reactions are maculopapular rashes1,2, and these are spontaneously relieved with a minimal dose of antihistamine or topical steroids. Several uncommon or severe reactions such as Stevens-Johnson syndrome have also been reported; however, they seem to be an idiosyncratic adverse reaction of hypersensitivity4. These reactions require the concomitant use of oral steroids, and immediate discontinuation of imatinib therapy is imperative4,5. Here, we observed a case of imatinib-induced EM. We noted a dose-dependent relation; thus, we consider that imatinib-induced EM is related to a pharmacological effect of imatinib. The skin lesion subsided and did not recur only with the concomitant use of low-dose oral steroids. As imatinib is a very effective therapeutic agent and alternative treatment options are limited, recognition of adverse cutaneous reactions after imatinib therapy and the appropriate management required is helpful.

A Novel Approach to a Retrospective Longitudinal Analysis of Dose Change or Discontinuation of Imatinib Therapy in Chronic Phase–Chronic Myeloid Leukemia

▪Imatinib (IM) is a cornerstone in the treatment of chronic myeloid leukemia (CML). Dose change or discontinuation of IM in patients who experience sustained molecular response is a subject of debate.We retrospectively studied 142 CML patients in chronic phase (Table 1) treated with IM and followed-up during 2000-2013 at our institution. Dose changes, discontinuation of therapy, cytogenetic and molecular analyses were regularly recorded during follow-up. Patients’ history was subdivided into 483 treatment time-periods at constant dosage. Response was evaluated at the end of each treatment period. We assessed whether the probability of observing a complete cytogenetic response (CCyR) or a molecular response (MR: complete, CMR or major, MMR) or a progression were influenced by treatment dose and/or duration.We applied generalized estimating equation (GEE) logistic models for the analysis of longitudinal panel data. These models are designed to account for individual patient variation due to repeated measurements during each patient’s follow-up.Out of 483 time periods at constant IM dose, 236 were followed by dose modification, 116 by IM discontinuation, 29 by a change to other treatments due to tolerability issues or non-response; 102 were still ongoing without dose changes.Treatment response: 74% of time periods resulted in a CCyR and 2.3% showed no response; 31.9% showed a CMR, 29.6% showed a MMR (MR3, MR4, MR4.5), 35.6% a suboptimal response, 2.9% no MR. CMR+MMR was observed in 61.5% time periods.Periods at standard dose showed a higher response rate, both when considering CCyR (response rate after low, standard, high dose: 69.3%, 79.6%, 68%, respectively, P=0.023) and when considering MR (CMR after low, standard, high dose: 27%, 40.5%, 15.4%, respectively, P<0.001; CMR + MMR after low, standard, high dose: 53.4%, 69.8%, 52.3%, respectively, P=0.001).After adjusting for length of treatment period in a multivariate GEE model, dose lost significance and treatment duration was the only significant predictor of CCyR (P<0.001).In a GEE analysis of MR accounting for treatment duration, reduction in CMR rate after periods at high dose compared with periods at standard dose remained significant (P=0.025). Treatment dose lost significance when considering CMR+MMR.In 32 patients who discontinued IM therapy for >1 mos and then re-started IM, the CR rate after a period preceded by a treatment suspension was significantly higher than in other periods (CCyR: 85.7% vs. 73%, P=0.058; CMR 55.1% vs. 29.3%, P=0.001). In a GEE model with dose category, duration of treatment and previous suspension as covariates, both duration and previous suspension maintained a positive significant association to CCyR (P<0.001, P=0.034, respectively), to CMR (both P<0.001) and to CMR+MMR (P<0.001, P=0.006, respectively).Cytogenetic progression rate at the end of a period of IM treatment was 7.1% while molecular progression rate was 12.8%.Treatment dose was not associated to progression: cytogenetic progression after low, standard, high dose: 6.1%, 6.7%, 10.5%, respectively, P=0.428; molecular progression after low, standard, high dose: 14.8%, 11.3%, 13%, respectively, P=0.584. In a multivariate GEE analysis, neither dose nor duration of treatment predicted progression. After adding type of previous treatment (IM, other drug, no treatment) as a covariate, treatment periods preceded by at least 1 month of discontinuation had a significantly lower molecular progression rate (P=0.011).The possibility of varying dosage is often considered in “real-life” patient clinical management. In our study, 62% of time periods were followed by a dose change, but this did not affect response and progression rate after accounting for length of treatment period. The prompt response to resumed IM therapy suggests that patients may be candidates for intermittent therapy.Future studies could use the same statistical model to pick up individual patient variation in longitudinal data collected over time, including trials at reduced IM dose or of “on-off” therapy or on new TKI.Table 1Patients’ characteristicVariableDescriptionN. of patients142Sex M/F58%/42%Age at diagnosis (years), median (range)52 (18-78)N. of IM treatment periods483IM dosage, N (%)Low dose (100-300 mg/day)163 (34%)Standard dose (400 mg/day)242 (50%)High dose (450-800 mg/day)78 (16%)Duration of IM at constant dosage (days), median (range)258 (7-4526) DisclosuresNo relevant conflicts of interest to declare.

The Risk of Relapse in CML Patients Who Discontinued imatinib Can Be Predicted Based on Patients Age and the Results of dPCR Analysis

▪Introduction. Chronic myeloid leukemia (CML) patients (pts) treated with imatinib first line achieve complete cytogenetic response (CCyR) in > 70% of cases and major molecular response (MMR) in 18-58%. These pts have a life expectancy similar to the general population. However even undetectable BCR-ABL may not equate to eradication of the disease because of the sensitivity of Q-RT-PCR. A new diagnostic method, the digital-PCR (dPCR), able to detect 1 BCR-ABL+ cell out of 107 cells, has been recently developed (Goh HG et al., 2011). dPCR corresponds to a 100 fold increase in sensitivity as compared to Q-RT-PCR. Therefore, dPCR by assessing the presence of minimal residual disease with higher sensitivity, could potentially identify pts in whom CML has been eradicated.Aims. The Imatinib Suspension And Validation (ISAV) study is aimed at validating the capability of dPCR to predict relapses after imatinib discontinuation in CML pts with negative Q-RT-PCR results.Methods. This study involves 15 sites, 10 in Italy and 1 in each of the following countries: Germany, Spain, The Netherlands, Canada and Israel. CML pts (Chronic or Accelerated Phase) under imatinib therapy since more than 2 years and in complete molecular remission (CMR) were eligible for this study. Patients had to be in CMR for at least 18 months (mts), with a minimum of 3 Q-RT-PCR performed at their own sites. After signing the informed consent, blood samples are obtained for dPCR and the pts discontinue imatinib therapy. Standard Q-RT-PCR is performed monthly (mts 1-6) and then bimonthly for 36 mts to assess the maintenance of the molecular remission. The loss of molecular remission is defined as two consecutive positive Q-RT-PCR tests with at least one BCR-ABL/ABL value above 0.1%. Patients losing molecular remission resume imatinib treatment at the same dosage used before interruption. Patients’ quality of life during imatinib discontinuation/resumption is evaluated through the EORTC – C30 Quality of Life questionnaire.Results. The enrolment in ISAV began in November 2011 and ended in July 2013. The study enrolled 112 pts: Italy 69.6%, Germany 21.4%, Canada 5.3%, Spain 2.6% and Israel 0.9%. Among the 112 pts, 59.3% were male and 37.0% were aged 65 or older; median duration of imatinib treatment was 103.1 mts with median duration of CMR of 25.8 mts before imatinib discontinuation. To date, the median follow-up (FUP) time is 16.6 mts [95% CI: 14.9-18.2]. Forty-seven pts (43.5%, 95% CI: 34.0-53.4) of the 108 eligible pts relapsed and resumed imatinib; 38/47 (80.9%) of them relapsed in the first 9 mts and the last relapse occurred 19.6 mts after imatinib discontinuation. A loss of CCyR occurred in 11 pts (23.4%): 10/11 CCyR losses were recovered; 1 patient withdrew the consent shortly after obtaining a partial cytogenetic response. No case of CML progression was observed. After the resumption of imatinib the median time to either MMR or CMR was 1.9 [95% CI: 1.2-2.4] mts. Of the 61 not-relapsed pts, 43 (39.8% of the total) regained Q-RT-PCR positivity but never lost MMR. The median time to Q-RT-PCR positivity was 3.6 mts [95% CI: 3.0-4.8] and the range of duration of Q-RT-PCR positivity (below 0.1%) was between 5.7 and 29.2 mts. No significant correlation between relapse and previous duration of imatinib treatment, use of interferon, time to CCyR or duration of CMR was identified. An inverse relationship between pts age and risk of relapse is evident: 90% of pts < 45 years relapsed vs 37.5% in the class ≥ 45 - < 65 years and 27.5% of pts ≥ 65 years, p(χ2)<0.0001. dPCR results showed that 23.4% of pts were positive and 76.6% negative, with a dPCR Negative Predictive Value (NPV) of 63.4% (Tab.1) and a significant NPV ratio (dPCR/Q-RT-PCR) of 1.131 [95% CI: 1.032-1.239]. Age and dPCR results predicted the risk of relapse: pts with less than 45 years and with a positive dPCR had the highest risk of relapse (100%) as opposed to pts ≥ 45 years and with negative dPCR (30.6%; Fig.1).Conclusions. After 32 mts from the beginning of the study, with a median FUP of 16.6 mts, 43.5% of pts relapsed; the majority of relapses developed in the first 9 months after imatinib discontinuation. Age < 45 years and dPCR positivity are significantly associated with relapses. Funded by Regione Lombardia. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Imatinib and pegylated IFN‐α2b discontinuation in first‐line chronic myeloid leukemia patients following a major molecular response

Previous studies indicate that 40-50% of patients with chronic myeloid leukemia in prolonged complete molecular remission may discontinue imatinib therapy without imminent relapse. The combination of pegylated interferon-alpha (Peg-IFN-α2b) and imatinib may increase the rate of successful discontinuation. In this pilot study, we prospectively stopped imatinib from patients (n = 12) who had achieved major molecular response (MMR) after ≥12 months of treatment with either imatinib or imatinib+Peg-IFN-α2b. Molecular monitoring was carried out monthly for BCR-ABL1. In addition, analyses of lymphocyte immunophenotype, function, and plasma cytokines were performed. In the monotherapy group, 5/6 patients lost MMR within 4 months. One patient remains to date in MR(4.0) 61 months after discontinuation. In the combination therapy group, 2/6 patients relapsed within 4 months while still receiving Peg-IFN-α2b. Four of six patients were able to discontinue both treatments, but three of these patients relapsed after 3 months. One patient is still in sustained MR(4.0) at 58 months off all treatment. All relapsed patients re-responded to imatinib. The two successfully discontinued patients had either an increased number of NK-cells or functionally active T-cells. A higher frequency of relapsed patients in our study in comparison with other studies may be due to the shorter duration of imatinib treatment prior to discontinuation. However, in selected patients with an active immune system, even a short duration of TKI therapy (<2 yr) may allow for therapy discontinuation but this needs to be confirmed in larger prospective studies.

Validation of Digital-PCR Analysis through Programmed imatinib Interruption in Q-RT-PCR Negative Chronic Myeloid Leukemia Patients

IntroductionImatinib induces complete cytogenetic response (CCyR) in up to 80% of chronic myeloid leukemia (CML) patients (pts) and major molecular response (MMR) in 33-60% of them. These patients enjoy life expectancy similar to general population. However even undetectable BCR-ABL may not equate to eradication of the disease because the sensitivity of the standard diagnostic method, the Q-RT-PCR, is limited. A new diagnostic method, the digital-PCR (dPCR), able to detect 1 BCR-ABL+ cell out of 107 cells, corresponding to a 100 times increased sensitivity as compared to conventional Q-RT-PCR, was developed (Goh HG et al., Leuk Lymphoma 52(5): 896-904. 2011). Therefore dPCR, assessing with more sensitivity the presence of minimal residual disease, could potentially identify pts in whom CML is eradicated. The Imatinib Suspension And Validation (ISAV) study is aimed at assessing the capability of dPCR to predict relapses after imatinib discontinuation in CML pts with negative Q-RT-PCR results. MethodsThis study involves 15 sites, 10 in Italy and 5 in each of the following countries: Germany, Spain, The Netherlands, Canada and Israel. In this study CML patients (Chronic Phase or Accelerated Phase) under imatinib therapy since more than 2 years and in complete molecular remission (CMR) were eligible. Patients had to be in CMR for at least 18 months, with a minimum of 3 Q-RT-PCR performed in their own centers. After signing the informed consent, pts were tested for dPCR and discontinued imatinib therapy. They are being monitored by standard Q-RT-PCR for 36 months to assess the maintenance of the molecular remission. At the end of this period, a peripheral blood sample for dPCR analysis will be obtained from those pts who will still have undetectable BCR-ABL transcripts by Q-RT-PCR, to verify CML eradication. The loss of molecular remission is defined as two consecutive positive Q-RT-PCR tests with at least one BCR-ABL/ABL value above 0.1%. Patients losing molecular remission resumed imatinib treatment at the same dosage used before interruption. Patients' quality of life during imatinib discontinuation/resumption is being evaluated trough the EORTC – C30 Quality of Life questionnaire. ResultsThe enrollment in the ISAV study began in November 2011 and ended in June 2013. The study enrolled 112 pts: Italy 69.6%, Berlin 21.4%, Montreal 5.3%, Zaragoza 2.6% and Tel Hashomer 0.9%. Sixty-one percent of the pts were male and 38% were aged 65 or older; median duration of imatinib treatment is 102 months with median duration of CMR of 32 months before imatinib discontinuation. To date, the median follow-up (FUP) time is 4.6 months [95% CI: 4.1-5.8] and 92 pts out of 112 (82%) had at least one Q-RT-PCR performed after imatinib discontinuation. The following analysis is restricted to 48 pts with a minimum of 6 months of FUP. Of these 48 pts, 20 remained Q-RT-PCR negative (42%, 95% CI:29-56%, median duration of negativity after imatinib discontinuation: 10.3 months). Nineteen pts (40%, 95% CI:27-53%) relapsed and resumed imatinib. All relapses occurred in the first 10 months and all but 3 of them in the first 6 months. A loss of CCyR happened in 5 pts out of 19 (26%): 1 pt regained CCyR after 3 months of re-treatment and is now in CMR, 1 pt died shortly after the diagnosis of relapse because of lung adenocarcinoma and 3 pts are now being monitored after imatinib resumption. No case of progression of CML was observed. After the resumption of imatinib the median time to either MMR or CMR, whichever came first, was 2.1 [95% CI: 0.9-5.8] months. Finally, nine pts (18%, 95% CI:10-31%) regained Q-RT-PCR positivity but never lost MMR. The median time to Q-RT-PCR positivity in this group of pts was 2.92 months (range 1-5 months), and the range of duration of Q-RT-PCR positivity (below 0.1%) is between 2 and 14 months. No significant correlation between relapse and previous duration of imatinib treatment, time to CCyR or duration of CMR was present. Patients previously treated with interferon showed a trend toward lower risk of relapse which is not significant so far. Finally, 19% of pts complained of musculoskeletal/articular pain after imatinib discontinuation. ConclusionsAfter 21 months from the beginning of the study with a median follow-up of 4.6 months, 40% of pts relapsed; the majority of relapses happened in the first 6 months after imatinib discontinuation. The correlation of dPCR results with clinical outcomes will be presented at the meeting. Disclosures:le Coutre:Novartis: Honoraria; BMS: Honoraria; Pfizer: Honoraria; Novartis: Research Funding. Gozzini:Novartis: Consultancy; Bristol Myers Squibb: Consultancy.

Activation Levels of Natural Killer Cells and CD8+ T Cells Correlate Highly with Sustained Complete Molecular Response After Discontinuation of Imatinib in Chronic Myeloid Leukemia Patients

AbstractAbstract 3745 Introduction:Recently, it has been recognized that some chronic myeloid leukemia (CML) patients with a complete molecular response (CMR) are able to maintain the CMR after discontinuation of imatinib. Mahon et al. reported that among patients with a CMR lasting at least 2 years, CMR was sustained in 41% after discontinuation of imatinib (Lancet Oncol. 2010;11:1029). Similarly, Takahashi et al. reported that 47% of Japanese CML patients with CMR maintained CMR after imatinib discontinuation (Haematologica 2012;97:903). Moreover, Ohyashiki et al. have recently demonstrated that higher peripheral natural killer (NK) cell counts are associated with a reduced risk of relapse after halting imatinib (Br. J. Haematol. 2012;157:254). These findings suggest that, although CML stem cells may remain, even if CMR status is attained, some CML patients could discontinue imatinib therapy and maintain a stable condition, possibly owing to immune surveillance. Aim:To more precisely identify these patients who can safely discontinue imatinib, we characterized the immunophenotype profiles of CML patients. We compared the profiles among CML patients who received imatinib with CMR for more than 2 consecutive years (CMR group), those who could not sustain CMR but maintained a major molecular response (fluctuated CMR group), those who sustained CMR for more than 6 months after discontinuation of imatinib (STIM group), those who relapsed after discontinuation of imatinib (relapse group), and healthy volunteers (control group). Methods:Peripheral blood mononuclear cells (PBMCs) from CML patients and healthy volunteers were separated using a Ficoll density gradient, and immunophenotyping analysis was performed with a 5-color flow cytometry panel, including antibodies against the following cell surface antigens and effector molecules: CD3, CD8, CD45RO, CD56, CCR7, IFN-g, granzyme B, and perforin. After PBMCs were stimulated with phorbol 12-myristate 13-acetate and ionomycin for 4 h in the presence of monensin, cell surface antigens were stained, fixed, and permeabilized. Resultant cells were then intracellularly stained and analyzed with the FACSCanto II flow cytometer. Results:The percentage of effector populations of NK cells, such as interferon (IFN)-g+CD3−CD56+ cells, was significantly higher in the CMR and STIM groups than in the control group. In contrast, the percentage of effector populations of CD8+ T cells, such as IFN-g+CD8+ T cells, was significantly higher in the STIM and control groups than in the CMR group. Moreover, the percentage of effector populations of NK cells, but not CD8+ T cells, was significantly higher in the CMR group than in the fluctuated CMR group. On the other hand, CML patients with a lower percentage of effector populations of NK cells and CD8+T cells, and those with a higher percentage of these effector populations, but whose percentage had decreased after imatinib cessation, had a tendency to relapse after discontinuation of imatinib. Conclusion:The percentage of effector populations of NK cells and CD8+ T cells, such as those expressing IFN-g, correlated highly with sustained CMR after discontinuation of imatinib. Moreover, the activation level of NK cells, but not CD8+ T cells, inversely correlated with the BCR-ABL1 transcript level. Taken together, these results suggest that whether imatinib treatment can be safely discontinued may depend greatly on the immunological activation status of both NK cells and CD8+ T cells in CML patients. Disclosures:No relevant conflicts of interest to declare.

Discontinuation of Imatinib Therapy in Chronic Myeloid Leukemia Patients with Sustained Complete Molecular Response4.5 (CMR4.5)

Abstract 2763Approximately 50% of CP CML patients achieve complete molecular response (CMR) at 6–7 years of first-line imatinib therapy. Although imatinib therapy is effective in CML patients and a substantial portion of patients achieve CMR with prolonged imatinib therapy, up to 10^7 leukemic cells can still be present in the absence of detectable BCR-ABL in RQ-PCR assay due to the sensitivity limit of current RQ-PCR technology. The recent data from STIM (Stop Imatinib) trial showed that the probability of persistent CMR at 12 month follow-up after imatinib discontinuation was 41%, and the conclusion was that imatinib can be safely discontinued, at least in some patients with persistent CMR. However, it is still not clearly defined whether discontinuation of imatinib therapy can be safely employed in patients with sustained CMR. In our prospective study, we examined if imatinib therapy can be safely discontinued in CML patients with sustained CMR4.5 according to strict PCR sensitivity criteria, and CMR4.5 was defined as undetectable BCR-ABL using RQ-PCR assay with at least 4.5-log sensitivity. CML patients who were treated with imatinib for more than 3 years and whose BCR-ABL was undetectable in RQ-PCR for at least 2 years were enrolled in this study. Our primary objectives were to evaluate the probability of persistent CMR4.5 at 12 month follow-up after discontinuation, and to measure the duration of persistent CMR4.5 after discontinuation. The secondary objective was to evaluate the probability of major molecular response (MMR) loss and the time taken to lose MMR at 12 month follow-up after discontinuation. In patients with loss of MMR, the probability of re-achieving MMR/CMR4.5 and the time taken to re-achieve MMR/CMR4.5 after imatinib resumption were also evaluated. After discontinuation, molecular response was monitored using RQ-PCR assay every month up to 6 month follow-up, every 2 months up to 12 month follow-up, and every 3 months thereafter. Digital PCR methodology with higher sensitivity compared to RQ-PCR assay was also applied before discontinuation and every year after discontinuation for more accurate estimation of BCR-ABL transcript levels. In case of relapse, defined as loss of MMR on 2 consecutive assessments, imatinib therapy was re-introduced and molecular response after resumption was observed using both RQ-PCR and digital PCR assays. As of data cut-off date of 15 Jul 2011, 20 patients (13 females, 7 males) who were diagnosed in Seoul St. Mary’s Hospital between 20 Mar 1996 and 25 Apr 2005 were enrolled in this study with a median follow-up of 7 months (range, 2–9), and informed consents were obtained from all patients prior to participation. With a median age of 44 years (range, 25–67), the percentages of patients with low, intermediate and high Sokal risk scores were 30%, 30% and 15%, respectively with unknown Sokal risk scores in 25%. Ten patients (50%) received SCT and/or interferon therapy prior to imatinib therapy, while 10 patients (50%) received first-line imatinib therapy. The median time on imatinib therapy and the median duration of sustained CMR4.5 were 91 months (range, 40–112) and 60 months (range, 23–104), respectively, prior to discontinuation. Since discontinuation of imatinib therapy, all of 20 patients remained off therapy at the last follow-up with persistent CMR4.5 in 18 patients (90%) and loss of CMR in 2 patients (10%). Although loss of CMR was observed in 2 patients, both patients have not resumed imatinib therapy as MMR was maintained at the last follow-up. Our preliminary data show lower relapse rate after discontinuation compared to previous discontinuation studies. Strict PCR sensitivity criteria should be employed to assess the accurate measurement of BCR-ABL transcript levels prior to discontinuation, and then it might be possible to safely stop imatinib therapy in CML patients with stable CMR4.5. Through further clinical investigation on a large patient population and longer period of observation, more concrete conclusion can be made regarding the outcome of imatinib discontinuation. Updated data with longer follow-up duration will be presented in the meeting. Disclosures:No relevant conflicts of interest to declare.

Second Line Therapy with Second Generation TKI After Intolerance to Imatinib Based Treatments Showed High Overall Survival in Contrast to Second Line Therapy After Resistance; Results of the Randomized CML Study IV

Abstract 781▪FN2▪This icon denotes a clinically relevant abstract Introduction:Data on second line therapy with second generation tyrosine kinase inhibitors (TKI) in CML treatment were generated mainly from phase II/III industry initiated trials (Review Hehlmann Exp Op. 2011). 24-month overall survival (OS) varies between 88% and 94% after intolerance and/or resistance to imatinib for chronic phase (CP) and between 67% and 72% for accelerated phase (AP) or blast crisis (BC). Intention to treat analyses including outcome of patients after discontinuation of first line therapies have not been available as yet. We thought to evaluate overall and progression-free survival (OS and PFS) of imatinib intolerant vs. resistant patients under second line TKI with long-term follow-up within an investigator initiated trial. Methods:We analyzed data of the German CML study IV, a randomized 5-arm trial to optimize imatinib therapy on an intention to treat basis. According to protocol, follow-up of patients on and after second generation TKI after imatinib intolerance and/or resistance was continued for OS and PFS. Analysis of PFS was only relevant, if intolerance and resistance to imatinib therapy occurred while a patient was still in chronic phase (CP). Patients were censored at the time of allogeneic stem cell transplantation (allo-SCT). Results:From July 2002 to December 2010, 1,502 patients with Philadelphia chromosome and /or BCR-ABL positive CML in CP were randomized. 129 patients of the “imatinib after interferon arm” and 36 other patients had to be excluded (14 due to incorrect randomization or withdrawal of consent, 22 with missing baseline information). 1337 were randomized to primary imatinib treatment (imatinib 400 mg vs. imatinib 800 mg vs. imatinib in combination with either interferon alpha or araC). Of these, 234 (17%) discontinued imatinib therapy. 156 patients were treated with 2nd generation TKI, 61 were directly referred to allo-SCT, 17 patients received other regimens (including interferon alpha only or hydroxyurea).120 of 156 patients started second generation TKI therapy (nilotinib, n=41, dasatinib, n=75, bosutinib, n=2, nilotinib and dasatinib, n=2) within 3 months after stopping imatinib, received treatment for at least one week and were evaluable for PFS and OS. 36 patients received second TKI later (median 10 months, range 3.5–61.4). Median age was 50 years (range 16–78), 42.5% were female. 48 patients were intolerant, 48 failed imatinib within CP and 24 after loss of CP (accelerated phase, n=10, blast crisis, n=14). Median time to second generation TKI was 17 months (range 1.4–97 months) and median follow-up after start of second-line TKI 31 months (range 0.2–71 months). Risk stratification according to the EUTOS Score was high in 20 patients (17%) and low in 94 patients (78%) and unknown in 6 patients (5%). OS for all 120 patients 3 years after start of second generation TKI was 73%, 96% for intolerant and 80% for resistant patients in CP and 19% for resistant patients in advanced disease (s. Fig. 1). According to EUTOS score, 3-year OS was 78% for low and 56% for high risk patients. Probability of PFS of the 96 patients in 1st CP after 3 years was 96% for intolerant and 76% for resistant patients. After 2nd generation TKI, 18 patients received an allo-SCT: all were in CP, 2 patients after imatinib intolerance, 16 patients after imatinib resistance. [Display omitted] Conclusion:Survival on second generation TKI is high for imatinib intolerant patients in first CP but much lower for resistant patients in first CP or for patients with advanced disease phases. Alternative treatment strategies are warranted for these patient groups. Disclosures:Krause:Micromet: Research Funding. Kneba:Hoffmann La Roche: Honoraria. Hochhaus:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Ariad: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. German CML Study Group:Deutsche Krebshilfe: Research Funding; Novartis: Research Funding; BMBF: Research Funding; EU: Research Funding; Roche: Research Funding; Essex: Research Funding.