A new diagnostic kit, ODK-1201, for the quantitation of low major BCR-ABL mRNA level in chronic myeloid leukemia: correlation of quantitation with major BCR-ABL mRNA kits

Decade-long WT1-specific CTLs induced by WT1 peptide vaccination

INTRODUCTION

The peptide-based cancer vaccine targeting Wilms' tumor 1 (WT1) is a promising immunotherapeutic strategy for hematological malignancies. It remains unclear how long and to what extent the WT1-specific CD8 + cytotoxic T cell (CTL) persist after WT1 peptide vaccination.

METHODS

The WT1 peptide vaccine was administered with written consent to a patient with CML in the chronic phase who did not respond well to imatinib, and the patient was followed for 12 years after vaccination. Immune monitoring was performed by specific amplification of WT1-specific CTLs using a mixed lymphocyte peptide culture. T-cell receptors (TCRs) of amplified WT1-specific CTLs were analyzed using next-generation sequencing. This study was approved by the Institutional Review Board of our institution.

RESULT

WT1-specific CTLs, which were initially detected during WT1 peptide vaccination, persisted at a frequency of less than 5 cells per 1,000,000 CD8 + T cells for more than 10 years. TCR repertoire analysis confirmed the diversity of WT1-specific CTLs 11 years after vaccination. CTLs exhibited WT1 peptide-specific cytotoxicity in vitro.

CONCLUSION

The WT1 peptide vaccine induced an immune response that persists for more than 10 years, even after cessation of vaccination in the CML patient.

Discontinuation of tyrosine kinase inhibitors in pediatric chronic myeloid leukemia

BACKGROUND

The feasibility of tyrosine kinase inhibitor (TKI) discontinuation in pediatric chronic myeloid leukemia (CML) remains to be fully elucidated.

PROCEDURES

TKI was prospectively discontinued in patients who were diagnosed with CML at <20 years of age, treated with TKI for ≥3 years, and sustained molecular response 4.0 (MR4.0) for ≥2 years. Molecular relapse was defined as a single loss of major molecular response (MMR) (BCR-ABL1^IS >0.1%). Relapsed patients resumed the same TKI therapy administered before discontinuation.

RESULTS

Twenty-two patients with chronic-phase CML were enrolled, and the median ages at diagnosis and at TKI discontinuation were 9 (range: 1-14) years and 16 (5-26) years, respectively. The median follow-up time after TKI discontinuation was 37 months (range: 24-41 months). The median duration of TKI treatment before discontinuation was 100 (42-178) months, and that of MR4.0 was 53.5 (25-148) months. The treatment-free remission (TFR) rate at 12 months was 50.0% (90% confidence interval: 31.7%-65.8%). Eleven patients experienced loss of MMR within 4 months after TKI discontinuation and resumed TKI as originally prescribed. No progression was observed, and all 11 patients regained MR4.0 after TKI resumption. No patient had a withdrawal syndrome. The quality-of-life analysis suggested that successful TFR may improve academic performance in some patients. In patients who discontinued TKI therapy before puberty, the possibility of improvement in growth velocity upon TKI discontinuation was observed.

CONCLUSIONS

TKI could be discontinued safely in patients with pediatric CML showing a sustained deep MR.

The EUTOS long-term survival score predicts disease-specific mortality and molecular responses among patients with chronic myeloid leukemia in a practice-based cohort

The European Treatment and Outcome Study (EUTOS) long‐term survival (ELTS) score predicts disease‐specific death in patients with chronic myeloid leukemia (CML) being treated with imatinib during the chronic phase (CP) of the disease. However, it is unclear whether the ELTS score predicts CML‐related events or treatment responses. This study evaluated the predictive value of the ELTS score regarding prognosis and treatment response in patients with CML‐CP. Clinical data were retrospectively obtained from patients enrolled in the CML Cooperative Study Group (CML‐CSG), which included patients diagnosed with CML‐CP from April 2001 to January 2016, and treated with any tyrosine kinase inhibitor (TKI) as first‐line therapy. Among 342 eligible patients, the ELTS scores indicated low‐, intermediate‐, and high‐risk in 74%, 21%, and 5% of patients, respectively. Patients with high ELTS scores had significantly higher disease‐specific mortality and worse event‐free survival, progression‐free survival, and overall survival. Among four risk scores, including the Sokal, Hasford, EUTOS, and ELTS scores, risk stratification by the ELTS score had the highest predictive value in assessing patient prognosis, and also in treatment responses. In fact, the EUTOS and ELTS scores were able to predict the major molecular response within 12 months. Most importantly, the ELTS score was the only scoring system that predicted deep molecular response at any time, regardless of risk level (65.0%, 43.7%, and 23.5% in low‐, intermediate‐, and high‐risk groups, respectively). Compared to other risk scores, the ELTS score was the most sensitive risk classification tool for the four endpoints of interest in this study, as well as molecular responses in patients with CML‐CP.

Influence of proton pump inhibitors and H2-receptor antagonists on the efficacy and safety of dasatinib in chronic myeloid leukemia patients

We evaluated the effect of proton pump inhibitors (PPIs) and H2-receptor antagonists (H2RAs) on the efficacy and safety of dasatinib for chronic-phase chronic myeloid leukemia (CP-CML). Retrospective analyses were performed for patients with CP-CML who received dasatinib at seven hospitals between April 2009 and December 2016. Seventy-three patients were identified, 16 of whom received PPIs or H2RAs concurrently with dasatinib. Major molecular response at 12 months was observed in 13 of 13 patients (100%) with concurrent PPIs or H2RAs (combination group), and in 23 of 51 patients (45.1%) who received only dasatinib (dasatinib-alone group; P < 0.001). Deep molecular response at 12 months was observed in four of six patients (66.7%) in the combination group, and seven of 38 patients (18.4%) in the dasatinib-alone group (P = 0.027). Dasatinib chemotherapy was stopped after 18 months for 25 patients (43.9%) from the dasatinib-alone group, but for none from the combination group. Combination treatment with PPIs or H2RAs did not reduce the efficacy of dasatinib. PPIs and H2RAs reduce the incidence of dasatinib discontinuation due to adverse events and increase the efficacy of dasatinib chemotherapy for patients.

Cessation of nilotinib in patients with chronic myelogenous leukemia who have maintained deep molecular responses for 2 years: a multicenter phase 2 trial, stop nilotinib (NILSt)

The aim of this multicenter phase 2 trial, Stop Nilotinib (NILSt), was to examine the safety and efficacy of discontinuation of nilotinib in patients with chronic phase (CP)-chronic myelogenous leukemia (CML). Patients with CP-CML who had achieved molecular response (MR^4.5) after initiation of imatinib or nilotinib therapy received consolidation therapy with nilotinib 300-400 mg twice daily for up to 24 months. Patients who maintained MR^4.5 at 24 months of consolidation therapy proceeded to discontinuation of nilotinib. The study enrolled 149 patients; 112 patients proceeded to consolidation therapy with nilotinib; 90 patients maintained MR^4.5 with consolidation therapy, and 87 proceeded to discontinuation of nilotinib. The treatment-free remission (TFR) (MR^4.5) rate at both 1 and 3 years after discontinuation of nilotinib was the same, at 60.9% (90% CI 51.6-69.7). Among 34 patients with molecular relapse, nilotinib was resumed in 33 patients; all of them attained MR^4.5. There was no significant association between molecular relapse and age, sex, Sokal score, previous interferon-α exposure, duration of tyrosine kinase inhibitors treatment, or trough concentration of nilotinib. With nilotinib, it might be possible to avoid prognostic factors for TFR that exist with imatinib discontinuation. Cessation of nilotinib after two years of consolidation was safe and feasible.Trial registration UMIN000007141.

Outcomes of unplanned tyrosine kinase inhibitor discontinuation in patients with chronic myeloid leukemia: retrospective analysis of real-world experience in a single institution

OBJECTIVES

To explore real-world prognoses for tyrosine kinase inhibitor (TKI) discontinuation in chronic myeloid leukemia (CML) patients and the associated reasons for TKI discontinuation.

METHODS

We investigated, using the medical records of 85 consecutive CML patients who received TKIs between December 2001 and August 2016 at our hospital, reasons for discontinuation, duration of TKI treatment before discontinuation, molecular response (MR) status at TKI discontinuation, treatment-free remission (TFR) duration, and overall survival after TKI discontinuation.

RESULTS

TKI therapy was discontinued in 21 patients. The median treatment duration before discontinuation was 68.3 months. The response statuses at discontinuation were MR⁴ (n = 2), MR^4.5 (n = 4), and ≥MR⁵ (n = 15). The reasons were pleural effusion (n = 5); requests for prolonged deep molecular response (DMR) (n = 4); ischemic heart disease, anemia, and economic problems (each, n = 3); renal dysfunction (n = 2); and hyperkalemia, diarrhea, dementia, asthma, and desire to get pregnant, (each, n = 1). All patients were alive with median follow-up period of 32.1 months. TFR was maintained in 14 patients, and the 2-year TFR proportion was 66.7%. Seven patients restarted TKI therapy and achieved MR⁴ within median of 3 months. The duration of TKI administration before discontinuation (≥ 70 months) was favored longer TFR durations.

CONCLUSION

TKI was safely discontinued in clinical practice and yielded TFR rates similar to those observed in previous clinical trials, regardless of reason. Achievement of TFR significantly impacts patients' quality of life and should be considered in clinical practice.

A new highly sensitive real-time quantitative-PCR method for detection of BCR-ABL1 to monitor minimal residual disease in chronic myeloid leukemia after discontinuation of imatinib

Tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL1 fusion protein, encoded by the Philadelphia chromosome, have drastically improved the outcomes for patients with chronic myeloid leukemia (CML). Although several real-time quantitative polymerase chain reaction (RQ-PCR) kits for the detection of BCR-ABL1 transcripts are commercially available, their accuracy and efficiency in laboratory practice require reevaluation. We have developed a new in-house RQ-PCR method to detect minimal residual disease (MRD) in CML cases. MRD was analyzed in 102 patients with CML from the DOMEST study, a clinical trial to study the rationale for imatinib mesylate discontinuation in Japan. The BCR-ABL1/ABL1 ratio was evaluated using the international standard (IS) ratio, where IS < 0.1% was defined as a major molecular response. At enrollment, BCR-ABL1 transcripts were undetectable in all samples using a widely-applied RQ-PCR method performed in the commercial laboratory, BML (BML Inc., Tokyo, Japan); however, the in-house method detected the BCR-ABL1 transcripts in five samples (5%) (mean IS ratio: 0.0062 ± 0.0010%). After discontinuation of imatinib, BCR-ABL1 transcripts were detected using the in-house RQ-PCR in 21 patients (21%) that were not positive using the BML method. Nineteen samples were also tested using a commercially available RQ-PCR assay kit with a detection limit of IS ratio, 0.0032 (ODK-1201, Otsuka Pharmaceutical Co., Tokyo, Japan). This method detected low levels of BCR-ABL1 transcripts in 14 samples (74%), but scored negative for five samples (26%) that were positive using the in-house method. From the perspective of the in-house RQ-PCR method, number of patients confirmed loss of MMR was 4. These data suggest that our new in-house RQ-PCR method is effective for monitoring MRD in CML.

Efficacy and safety of switching to nilotinib in patients with CML-CP in major molecular response to imatinib: results of a multicenter phase II trial (NILSw trial)

We evaluated the efficacy and safety of switching to nilotinib in CML-CP patients who had achieved MMR with continuous detectable BCR-ABL1 transcript levels after long-term imatinib treatment. Patients who had achieved MMR, but not deep molecular response (DMR), after > 18 months from the initiation of imatinib received nilotinib 400 mg twice daily for up to 24 months. BCR-ABL1 transcript levels were assessed every 3 months. Thirty-eight patients with a median age of 57.5 years (range 22-76 years) were evaluated. Twenty-seven patients completed 24 months of nilotinib treatment; 11 discontinued nilotinib due to retraction of consent (three patients), loss of MMR (1), intolerance (3) or AEs (5). Twenty patients [52.6%, (90% CI 38.2-66.7%)] achieved DMR. The cumulative incidence of achieving DMR by the time of 3, 6, 9, 12, 15, 18, and 21 months was 22.9, 37.7, 47.0, 53.7, 53.7, 53.7, and 53.7%, respectively. Adverse events were consistent with those reported in other nilotinib studies. Patients experienced each of the following cardiovascular complications: atrial fibrillation (G2), chest tightness and dyspnea (G1), myocardial infarction (G2) and heart failure (G3) (n = 1 for each complication). This study indicates nilotinib achieves strong, rapid induction of DMR for patients who achieved MMR after long-term imatinib therapy.

Molecular monitoring in chronic myeloid leukemia-how low can you go?

Molecular monitoring of BCR-ABL1 transcripts for patients with chronic myeloid leukemia (CML) is now used to assess response to tyrosine kinase inhibitors (TKIs), including treatment failure that mandates a change of therapy. Therefore, many centers have adopted the molecular technique for measuring BCR-ABL1 and rely on conversion of values to the international reporting scale for appropriate clinical interpretation. However, the technique has a degree of inherent variability despite standardized procedures, which means care should be taken by the clinician when assessing response based on BCR-ABL1 cutoff limits. The last few years have witnessed the emergence of a new molecular response target, which is the achievement and maintenance of a deep molecular response. The ability to achieve treatment-free remission for some patients has shifted the relevant boundary for molecular response. However, the definitive safe BCR-ABL1 transcript level and length of the maintenance phase after which treatment cessation can be attempted has not yet been determined. For patients with TKI resistance, BCR-ABL1 kinase domain mutation analysis remains an essential assessment to guide therapy. Furthermore, low-level mutation detection is clinically relevant for response prediction to subsequent TKI therapy for some patients. Multiple low-level mutations may be a biomarker of a clonally diverse disease with the propensity for resistance evolution. Overall, molecular monitoring, including low-level monitoring is a fundamental component of management for patients with CML.

Is Adherence to Imatinib Mesylate Treatment Among Patients with Chronic Myeloid Leukemia Associated with Better Clinical Outcomes in Qatar?

BACKGROUND

Despite the revolutionary success of introducing tyrosine kinase inhibitors (TKIs), such as imatinib mesylate (IM), for treating chronic myeloid leukemia (CML), a substantial proportion of patients' treatments fail.

AIM

This study investigates the correlation between patient adherence and failure of TKIs' treatment in a follow-up study.

METHODS

This is a follow-up study of a new cohort of CML patients. Adherence to IM is assessed using the Medication Event Monitoring System (MEMS 6 TrackCap, AARDEX Ltd). The 9-item Morisky Medication Adherence Scale, medication possession ratio (MPR) calculation, and the electronic medical records are used for identifying potential factors that influence adherence. Clinical outcomes are assessed according to the European Leukemia Net 2013 guidelines via reverse transcriptase quantitative polymerase chain reaction measurement of the level of BCR-ABL1 transcripts in peripheral blood. Response is classified at the hematological, cytogenetic, and molecular levels into optimal, suboptimal, or failure.

RESULTS

A total of 36 CML patients (5 citizens and 31 noncitizen residents) consented to participate in the study. The overall mean MEMS score was 89. Of the 36 patients, 22 (61%) were classified as adherent (mean: 95) and 14 (39%) were classified as nonadherent (mean: 80.2). Adherent patients were significantly more likely to obtain optimal response (95%) compared to the nonadherent group (14.3%; P < 0.0001). The rate of poor adherence was as high as 39% using MEMS, which correlates with 37% treatment failure rate. The survey results show that 97% of patients increased the IM dose by themselves when they felt unwell and 31% of them took the missing IM dose when they remembered. Other factors known to influence adherence show that half of patients developed one or more side effects, 65% of patients experienced lack of funds, 13% of patients declared unavailability of the drug in the NCCCR pharmacy, and 72% of patients believed that IM would cure the disease. The MPR results reveal that 16% of patients had poor access to treatment through the hospital pharmacy.

DISCUSSION AND CONCLUSION

This is the first prospective study to evaluate CML patients' adherence and response to IM in Qatar. The high rate of treatment failure observed in Qatar is explained by poor adherence. An economic factor (unaffordable drug prices) is one of the main causes of nonadherence and efforts should be made locally to improve access to medication for cancer diseases. Other risk factors associated with poor adherence could be improved by close monitoring and dose adjustment. Monitoring risk factors for poor adherence and patient education that include direct communication between the health-care teams, doctors, nurses, pharmacists, and patients are essential components for maximizing the benefits of TKI therapy and could rectify this problem. The preliminary results show that patients' response to treatment may be directly linked to patients' adherence to treatment. However, further in-depth and specific analysis may be necessary in a larger cohort.

Validation of a rapid one-step high sensitivity real-time quantitative PCR system for detecting major BCR-ABL1 mRNA on an International Scale

BACKGROUND

Detection and quantitation of BCR-ABL1 transcripts are crucial for managing patients with chronic myeloid leukemia (CML). Although real-time quantitative polymerase chain reaction (RT-qPCR) can be measured on an International Scale (IS), this has not become fully universal. By using a WHO international standard panel established for calibrating secondary standards based on the IS, we have previously developed an RT-qPCR kit, ODK-1201, for quantification of major BCR-ABL1.

RESULTS

In this study, the reliability of kit-specific conversion factor 1.12 was validated by exchanging patients' samples between three local clinical laboratories and a reference laboratory. The mean bias of the local method after IS conversion was 1.6 fold lower than the reference method. The clinically-useful sensitivity of the kit was further evaluated for monitoring patients with deep molecular response. Based on the correlation of the IS values between ODK-1201 and the reference laboratory method, the detection level of the kit was estimated as 0.0032 % BCR-ABL1 (IS).

CONCLUSIONS

ODK-1201 is a highly sensitive one-step RT-qPCR system for detecting BCR-ABL1 on the IS in 2 h after RNA extraction, thus contributing to standardization of molecular monitoring in CML.