Intermittent target inhibition with dasatinib 100 mg once daily preserves efficacy and improves tolerability in imatinib-resistant and -intolerant chronic-phase chronic myeloid leukemia

PURPOSE

Dasatinib is a BCR-ABL inhibitor, 325-fold more potent than imatinib against unmutated BCR-ABL in vitro. Phase II studies have demonstrated efficacy and safety with dasatinib 70 mg twice daily in chronic-phase (CP) chronic myelogenous leukemia (CML) after imatinib treatment failure. In phase I, responses occurred with once-daily administration despite only intermittent BCR-ABL inhibition. Once-daily treatment resulted in less toxicity, suggesting that toxicity results from continuous inhibition of unintended targets. Here, a dose- and schedule-optimization study is reported.

PATIENTS AND METHODS

In this open-label phase III trial, 670 patients with imatinib-resistant or -intolerant CP-CML were randomly assigned 1:1:1:1 between four dasatinib treatment groups: 100 mg once daily, 50 mg twice daily, 140 mg once daily, or 70 mg twice daily.

RESULTS

With minimum follow-up of 6 months (median treatment duration, 8 months; range, < 1 to 15 months), marked and comparable hematologic (complete, 86% to 92%) and cytogenetic (major, 54% to 59%; complete, 41% to 45%) response rates were observed across the four groups. Time to and duration of cytogenetic response were similar, as was progression-free survival (8% to 11% of patients experienced disease progression or died). Compared with the approved 70-mg twice-daily regimen, dasatinib 100 mg once daily resulted in significantly lower rates of pleural effusion (all grades, 7% v 16%; P = .024) and grade 3 to 4 thrombocytopenia (22% v 37%; P = .004), and fewer patients required dose interruption (51% v 68%), reduction (30% v 55%), or discontinuation (16% v 23%).

CONCLUSION

Dasatinib 100 mg once daily retains the efficacy of 70 mg twice daily with less toxicity. Intermittent target inhibition with tyrosine kinase inhibitors may preserve efficacy and reduce adverse events.

Loss of major molecular response as a trigger for restarting tyrosine kinase inhibitor therapy in patients with chronic-phase chronic myelogenous leukemia who have stopped imatinib after durable undetectable disease

PURPOSE

More than half of patients with chronic-phase chronic myelogenous leukemia (CP-CML) in complete molecular response (CMR) experience molecular relapse after imatinib discontinuation. We investigated loss of major molecular response (MMR) as a criterion for resuming therapy.

PATIENTS AND METHODS

A multicenter observational study (A-STIM [According to Stop Imatinib]) evaluating MMR persistence was conducted in 80 patients with CP-CML who had stopped imatinib after prolonged CMR.

RESULTS

Median time from imatinib initiation to discontinuation was 79 months (range, 30 to 145 months);median duration of CMR before imatinib discontinuation was 41 months (range, 24 to 96 months); median follow-up after discontinuation was 31 months (range, 8 to 92 months). Twenty-nine patients (36%) lost MMR after a median of 4 months off therapy (range, 2 to 17 months). Cumulative incidence of MMR loss was estimated as 35% (95% CI, 25% to 46%) at 12 months and 36% (95% CI, 26% to 47%) at 24 months, whereas probability of losing CMR was higher. Fluctuation of BCR-ABL transcript levels below the MMR threshold (≥ two consecutive positive values) was observed in 31% of patients after imatinib discontinuation. Treatment-free remission was estimated as 64% (95% CI, 54% to 75%) at 12 and 24 months and 61% (95% CI, 51% to 73%) at 36 months. Median to time to second CMR was estimated as 7.3 months in re-treated patients.

CONCLUSION

Loss of MMR is a practical and safe criterion for restarting therapy in patients with CML with prolonged CMR.

Imatinib combined with induction or consolidation chemotherapy in patients with de novo Philadelphia chromosome-positive acute lymphoblastic leukemia: results of the GRAAPH-2003 study

The combination of imatinib with chemotherapy has been recently reported as very promising in patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). During 2004 and 2005, 45 patients with newly diagnosed Ph+ ALL were treated in the Group for Research on Adult Acute Lymphoblastic Leukemia (GRAAPH) 2003 study, in which imatinib was started with HAM (mitoxantrone with intermediate-dose cytarabine) consolidation in good early responders (corticosensitive and chemosensitive ALL) or earlier during the induction course in combination with dexamethasone and vincristine in poor early responders (corticoresistant and/or chemoresistant ALL). Imatinib was then continuously administered until stem cell transplantation (SCT). Overall, complete remission (CR) and BCR-ABL real-time quantitative polymerase chain reaction (RQ-PCR) negativity rates were 96% and 29%, respectively. All of the 22 CR patients (100%) with a donor actually received allogeneic SCT in first CR. At 18 months, the estimated cumulative incidence of relapse, disease-free survival, and overall survival were 30%, 51%, and 65%, respectively. These 3 end points compared very favorably with results obtained in the pre-imatinib LALA-94 trial. This study confirms the value of the combined approach and encourages prospective trials to define the optimal chemotherapy that has to be combined with imatinib and to carefully reevaluate the place of allogeneic SCT in this new context.

Lung abnormalities after dasatinib treatment for chronic myeloid leukemia: a case series

Tyrosine kinase inhibitors have revolutionized the treatment of chronic myeloid leukemia and are increasingly used for other indications. Fluid retention, however, including pleural effusions, are a significant side effect of imatinib, the first-line treatment for chronic myeloid leukemia. We investigated pleural and pulmonary complications in patients treated with dasatinib, a novel multitargeted tyrosine kinase inhibitor, as part of clinical trial protocols. Of 40 patients who received dasatinib (70 mg twice daily) for imatinib resistance or intolerance, 9 (22.5%) developed dyspnea, cough, and chest pain. Of these nine patients, six had pleural effusions (all were exudates) and seven had lung parenchyma changes with either ground-glass or alveolar opacities and septal thickening (four patients had both pleural effusions and lung parenchyma changes). Lymphocytic accumulations were detected in pleural and bronchoalveolar lavage fluids in all patients except for one who presented with neutrophilic alveolitis. Pleural biopsies revealed lymphocytic infiltration in one patient and myeloid infiltration in another. After dasatinib interruption, lung manifestations resolved in all cases and did not recur in three of four patients when dasatinib was reintroduced at a lower dose (40 mg twice daily). Thus, lung physicians should be aware that lung manifestations, presumably related to an immune-mediated mechanism rather than fluid retention, may occur with dasatinib treatment.

Combined treatment with arsenic trioxide and all-trans-retinoic acid in patients with relapsed acute promyelocytic leukemia

PURPOSE

Arsenic trioxide (ATO) is capable of inducing a high hematologic response rate in patients with relapsed acute promyelocytic leukemia (APL). Preclinical observations have indicated that all-trans-retinoic acid (ATRA) may strongly enhance the response to ATO.

PATIENTS AND METHODS

Between 1998 and 2001, we conducted a randomized study of ATO alone versus ATO plus ATRA in 20 patients with relapsed APL, all previously treated with ATRA-containing chemotherapy. The primary objective was to demonstrate a significant reduction in the time necessary to obtain a complete remission (CR) in the ATO/ATRA group compared with the ATO group. Secondary objectives were safety and molecular response.

RESULTS

The CR rate after one ATO with or without ATRA induction cycle was 80%. Clinical and pharmacokinetic observations indicated that the main mechanism of action of ATO in vivo was the induction of APL cell differentiation. Hematologic and molecular response, time necessary to reach CR, and outcome were comparable in both treatment groups. Of 16 CR patients, three patients who reached a molecular remission after one induction cycle had all received chemotherapy for a treatment-induced hyperleukocytosis. Three additional patients who received further additional ATO with or without ATRA cycles converted later to molecular negativity.

CONCLUSION

ATRA did not seem to significantly improve the response to ATO in patients relapsing from APL. Other potential combinations, including ATO plus chemotherapy, have to be tested.

Long-term follow-up of the imatinib GRAAPH-2003 study in newly diagnosed patients with de novo Philadelphia chromosome-positive acute lymphoblastic leukemia: a GRAALL study

We report here the results of the GRAAPH-2003 trial with long-term follow-up in 45 patients with de novo Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). Imatinib-based strategy improved the 4-year overall survival (OS) up to 52% versus 20% in the pre-imatinib LALA-94 trial (P = .0001). Despite the selection in patients who actually underwent transplantation, these results suggest that allogeneic or autologous stem cell transplants (SCTs) still have a place in overcoming the poor prognosis of Ph+ ALL in the era of imatinib therapy. OS was 50% after allogeneic SCT (24 patients), 33% in patients without a transplantation (9 patients), and 80% after autologous SCT (10 patients without allogeneic donor or >55 years, including 7 patients in complete molecular response).

Asciminib vs bosutinib in chronic-phase chronic myeloid leukemia previously treated with at least two tyrosine kinase inhibitors: longer-term follow-up of ASCEMBL

Asciminib, the first BCR::ABL1 inhibitor that Specifically Targets the ABL Myristoyl Pocket (STAMP), is approved worldwide for the treatment of adults with Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase (CML-CP) treated with ≥2 prior tyrosine kinase inhibitors (TKIs). In ASCEMBL, patients with CML-CP treated with ≥2 prior TKIs were randomized (stratified by baseline major cytogenetic response [MCyR]) 2:1 to asciminib 40 mg twice daily or bosutinib 500 mg once daily. Consistent with previously published primary analysis results, after a median follow-up of 2.3 years, asciminib continued to demonstrate superior efficacy and better safety and tolerability than bosutinib. The major molecular response (MMR) rate at week 96 (key secondary endpoint) was 37.6% with asciminib vs 15.8% with bosutinib; the MMR rate difference between the arms, after adjusting for baseline MCyR, was 21.7% (95% CI, 10.53-32.95; two-sided p = 0.001). Fewer grade ≥3 adverse events (AEs) (56.4% vs 68.4%) and AEs leading to treatment discontinuation (7.7% vs 26.3%) occurred with asciminib than with bosutinib. A higher proportion of patients on asciminib than bosutinib remained on treatment and continued to derive benefit over time, supporting asciminib as a standard of care for patients with CML-CP previously treated with ≥2 TKIs.

Expert opinion-management of chronic myeloid leukemia after resistance to second-generation tyrosine kinase inhibitors

Regardless of line of therapy, treatment goals in chronic phase chronic myeloid leukemia (CML) are: avoid progression to accelerated phase or blast crisis CML such that patients achieve a life expectancy comparable with that of the general population; avoid adverse events (AEs); and restore and maintain quality of life. The most important prognostic factor for achieving these goals is response to tyrosine kinase inhibitors (TKIs) at key milestones. For patients failing a TKI, a treatment change is mandatory to limit the risk of progression and death. There is currently no precise guideline for patients that fail a second-generation TKI, and there is a paucity of data to guide clinical decision making in this setting. There is, therefore, an unmet need for practical and actionable guidance on how to manage patients who fail a second-generation TKI. Although the term 'failure' includes patients failing for resistance or intolerance, the focus of this paper is failure of a second-generation TKI because of resistance. CML patients who fail their first second-generation TKI for true resistance need a more potent therapy. In these patients, the key issues to consider are the relative appropriateness of early allogeneic hematopoietic stem cell transplantation or the use of a further TKI. Selection of the next line of treatment after second-generation TKI resistance should be individualized and must be based on patient-specific factors including cytogenetics, mutation profile, comorbidities, age, previous history of AEs with prior TKI therapy, and risk profile for AEs on specific TKIs. This expert opinion paper is not in conflict with existing recommendations, but instead represents an evolution of previous notions, based on new data, insights, and clinical experience. We review the treatment options for patients resistant to second-generation TKI therapy and provide our clinical opinions and guidance on key considerations for treatment decision making.

Second transplant with two unrelated cord blood units for early graft failure after haematopoietic stem cell transplantation

Graft failure (GF) can be a fatal complication following haematopoietic stem cell transplantation (HSCT). We report four patients who developed early GF after unrelated HSCT and who subsequently received a double unrelated cord blood transplant (dUCBT) after reduced-intensity conditioning, at a median 15 d after the decision to perform a second transplant. Neutrophil recovery was observed in all four patients between day +15 and +31 with full donor chimaerism of one unit. Acute GVHD grades II-IV was observed in three patients. Three are alive, between 12 and 25 months after dUCBT. In conclusion, dUCBT is a promising procedure to treat early GF.

Chronic neutrophilic leukemia. A study of four cases

Chronic neutrophilic leukemia (CNL) is a very rare entity, which has to be included among the chronic myeloid leukemias. Once an underlying cause of neutrophilia is excluded, the diagnosis of CNL is based on exclusion of chronic granulocytic and other types of chronic myeloid leukemias. The classification proposed by Sheperd et al. has proven to be helpful, but it must be completed by cytogenetic analysis and the search for bcr rearrangement by molecular biology methods, in order to confirm the absence of Philadelphia chromosome and of bcr-abl hybrid gene. We report here four cases of CNL, with confirmed absence of bcr rearrangement in two cases. Two patients died, 12 and 8 years after diagnosis, the second one following transformation into myelofibrosis with myeloid metaplasia. The other two died of acute myelogenous leukemia, the first one, 25 years after diagnosis of CNL, following a 3-year phase of acceleration. The last patient presented combined features of CNL and refractory anemia with excess of blasts, and was characterized by both progressive leukocytosis and severe thrombocytopenia; acute transformation into acute myelogenous leukemia occurred 6 months after diagnosis and death 1 month later. Among the 30 cases reported so far, plus the four presented here, combined myelodysplastic features were observed in five cases and transformation into acute myelogenous leukemia in six. Chronic neutrophilic leukemias should be reported regularity, in view of the uncertain and low frequency of this hematological disease.

Longer treatment duration and history of osteoarticular symptoms predispose to tyrosine kinase inhibitor withdrawal syndrome

The effectiveness of tyrosine kinase inhibitors (TKIs) has made it possible to consider treatment discontinuation in chronic myeloid leukaemia (CML) patients that achieve an excellent response. However, a few of the patients included in the Europe Stop Tyrosine Kinase Inhibitors (EURO-SKI) trial reported musculoskeletal pain shortly after stopping TKIs, considered as a withdrawal syndrome (WS). To identify factors that may predispose to TKI WS, we analysed the pharmacovigilance declarations for the 6 months after stopping TKIs in a large cohort of CML (n = 427) that combined the French patients included in the STop IMatinib 2 (STIM2; n = 224) and EURO-SKI (n = 203) trials. Among these patients, 23% (99/427) developed TKI WS after stopping imatinib (77/373; 20·4%), nilotinib (12/29; 41·4%) or dasatinib (10/25; 40%). WS concerned mainly the upper body joints, and required multiple symptomatic treatments in 30% of patients. Univariate and multivariate analyses identified two risk factors: duration of TKI treatment [risk ratio (RR) = 1·68 (1·02-2·74)] with a 93-month cut-off time, and history of osteoarticular symptoms [RR = 1·84 (1·04-3·28)]. These findings confirm that WS is a TKI class effect. CML patients should be carefully screened before treatment initiation to identify pre-existent osteoarticular symptoms. Moreover, before TKI discontinuation, patients should be informed of the possibility of WS, particularly after a long treatment period.

Intermediate maturation of Mycobacterium tuberculosis LAM-activated human dendritic cells

Contrasting observations raise the question of the role of mycobacterial derived products as compared with the whole bacterium Mycobacterium tuberculosis on maturation and function of human dendritic cells (DCs). DC-SIGN has been identified as the key DC receptor for M. tuberculosis through its interaction with the mannosylated lipoarabinomannan (ManLAM). Although ManLAM is a major mycobacterial component released from infected antigen-presenting cells, there is no formal evidence yet for an effect of ManLAM per se on DC maturation and function. DCs activated with purified ManLAM displayed an intermediate maturation phenotype as compared with lipopolysaccharide fully matured DCs with reduced expression of MHC class I and class II molecules, CD83 and CD86 and of the chemokine receptor CCR7. They were sensitive to autologous natural killer (NK) lysis, thus behaving like immature DCs. However, ManLAM-activated DCs lost phagocytic activity and triggered priming of naive T-cells, confirming their intermediate maturation. Partial maturation of ManLAM-activated DCs was overcome by triggering the CD40/CD40L pathway as a second signal, which completed maturation phenotypically and abolished autologous NK lysis susceptibility. Altogether, these data provide evidence that ManLAM may induce a partial maturation phenotype on non-infected bystander DCs during infection suggesting that ManLAM released from infected cells might impair adaptive immune response towards M. tuberculosis.

Cartridge-based automated BCR-ABL1 mRNA quantification: solving the issues of standardization, at what cost?

BACKGROUND

Molecular monitoring of chronic myeloid leukemia patients treated with tyrosine kinase inhibitors is essential for therapeutic stratification. Inter-laboratory reproducibility is, therefore, a crucial issue which requires standardization and strict alignment of BCR-ABL1 values to the international scale. An automated cartridge-based assay (Xpert BCR-ABL Monitor(™), Cepheid) had been proposed as a robust alternative to non-automated assays. This study aimed to compare inter-laboratory reproducibility of automated and non-automated quantification, the possibility of converting automated results to the international scale, and the potential economic impact of automation.

DESIGN AND METHODS

One hundred and eighteen blood samples from chronic myeloid leukemia patients treated with tyrosine kinase inhibitors were prospectively analyzed in two laboratories using both automated and non-automated assays. The economic evaluation involved a micro-costing study and average costs were assessed as a function of sample throughput.

RESULTS

Automated assays achieved similar inter-laboratory reproducibility to highly standardized non-automated assays and a short delay (≤6 h) between sampling and blood lysis had a positive impact on inter-laboratory reproducibility. Reporting automated BCR-ABL1 ratios on the international scale was possible using a specific conversion factor which may vary with batches. Cost assessment showed that automated assays could be relevant for annual activity levels below 300 since average costs were lower than those of the non-automated assays.

CONCLUSIONS

The Xpert BCR-ABL Monitor(™) assay could be appropriately used in a near-patient setting for routine quantification of e13/e14-a2 transcripts, preferably in partnership with a regional reference laboratory. However, its prognostic impact relative to non-automated quantification remains to be tested prospectively within appropriate clinical trials.

Long-term safety and efficacy of imatinib mesylate (Gleevec®) in elderly patients with chronic phase chronic myelogenous leukemia: results of the AFR04 study

Data from registries suggest that the median age of chronic myelogenous leukemia (CML) patients is 10-15 years older than that of clinical trials. We conducted a prospective phase II study to evaluate imatinib mesylate (IM, 400 mg daily) in newly diagnosed chronic phase CML (CP-CML) patients. Patients aged 70 years and over diagnosed with CP-CML within 12 months were eligible. Thirty patients were enrolled from April 2002 to October 2004. Median age was 74.8 years (range, 70-90). Male/female ratio was 1.72. At inclusion, comorbidities were reported in all but one patient, Cumulative Illness Rating Scale for Geriatrics comorbidity mean index was 1.47, and 66% of patients had cardiovascular disease. The median daily IM dose was 392 mg (range, 256-445). IM was interrupted in patients with severe comorbidities. Treatment discontinuation was observed in 36.6% of patients. Cumulative incidence of complete cytogenetic response was 71.4 and 78.5% at 12 and 24 months, respectively. A high level of sustained responses was observed in patients with mild or moderate comorbidities. Seven-year estimated overall survival was 80.8% (95% CI: 59.0-91.7). Two-thirds of the patients were still on long-term therapy at cut-off, and no patients had died from progression. This trial was registered at http://www.clinicaltrials.gov as # NCT00219765.

Dasatinib dose optimisation based on therapeutic drug monitoring reduces pleural effusion rates in chronic myeloid leukaemia patients

Dasatinib is a second-generation BCR-ABL1 tyrosine kinase inhibitor approved for patients with chronic myeloid leukaemia (CML). Dasatinib 100 mg per day is associated with an increased risk of pleural effusion (PlEff). We randomly evaluated whether therapeutic drug monitoring (TDM) may reduce dasatinib-associated significant adverse events (AEs) by 12 months (primary endpoint). Eligible patients started dasatinib at 100 mg per day followed by dasatinib (C)min assessment. Patients considered overdosed [(C)min ≥ 3 nmol/l) were randomised between a dose-reduction strategy (TDM arm) and standard of care (control arm). Out of 287 evaluable patients, 80 patients were randomised. The primary endpoint was not met due to early haematological AEs occurring before effective dose reduction. However, a major reduction in the cumulative incidence of PlEff was observed in the TDM arm compared to the control arm (4% vs. 15%; 11% vs. 35% and 12% vs. 39% at one, two and three years, respectively (P = 0·0094)). Molecular responses were superimposable in all arms. Dasatinib TDM during treatment initiation was feasible and resulted in a significant reduction of the incidence of PlEff in the long run, without impairing molecular responses. (NCT01916785; https://clinicaltrials.gov).

Bone marrow mesenchymal stromal cell (MSC) gene profiling in chronic myeloid leukemia (CML) patients at diagnosis and in deep molecular response induced by tyrosine kinase inhibitors (TKIs)

Although it has been well-demonstrated that bone marrow mesenchymal stromal cells (MSCs) from CML patients do not belong to the Ph1-positive clone, there is growing evidence that they could play a role in the leukemogenesis process or the protection of leukemic stem cells from the effects of tyrosine kinase inhibitors (TKIs). The aim of the present study was to identify genes differentially expressed in MSCs isolated from CML patients at diagnosis (CML-MSCs) as compared to MSCs from healthy controls. Using a custom gene-profiling assay, we identified six genes over-expressed in CML-MSCs (BMP1, FOXO3, MET, MITF, NANOG, PDPN), with the two highest levels being documented for PDPN (PODOPLANIN) and NANOG. To determine whether this aberrant signature persisted in patients in deep molecular response induced by TKIs, we analyzed MSCs derived from such patients (MR-MSCs). This analysis showed that, despite the deep molecular responses, BMP1, MET, MITF, NANOG, and PDPN mRNA were upregulated in MR-MSCs. Moreover, BMP1, MITF, and NANOG mRNA expressions in MR-MSCs were found to be intermediate between control MSCs and CML-MSCs. These results suggest that CML-MSCs exhibit an abnormal gene expression pattern which might have been established during the leukemogenic process and persist in patients in deep molecular response.

Development of Asciminib, a Novel Allosteric Inhibitor of BCR-ABL1

Chronic myeloid leukemia (CML) is driven by a translocation event between chromosomes 9 and 22, leading to the formation of a constitutively active BCR-ABL1 oncoprotein. Approved tyrosine kinase inhibitors (TKIs) for CML inhibit BCR-ABL1 by competitively targeting its adenosine triphosphate (ATP)-binding site, which significantly improves patient outcomes. However, resistance to and intolerance of TKIs remains a clinical challenge. Asciminib is a promising investigational agent in development that allosterically targets BCR-ABL1 in a non-ATP-competitive manner. It binds to the ABL1 myristoyl-binding pocket and is effective against most ABL1 kinase domain mutations that confer resistance to ATP-competitive TKIs, including the T315I mutation. This review discusses unmet needs in the current CML treatment landscape, reports clinical data from asciminib trials that support the use of single-agent asciminib as third-line therapy and beyond, and explores the potential benefit of asciminib in combination with approved TKIs in earlier lines.

Killer immunoglobulin-like receptor genotypes and chronic myeloid leukemia outcomes after imatinib cessation for treatment-free remission

Background

Natural Killer (NK) cells are innate lymphoid cells that can be cytotoxic toward a large panel of solid tumors and hematological malignancies including chronic myeloid leukemia (CML). Such a cytotoxicity depends on various receptors. Killer immunoglobulin‐like receptors (KIR) belong to these receptors and are involved in maturation process, then in the activation abilities of NK cells. Methods: We investigated the prognostic impact of the KIR2DL5B genotype in 240 CML patients included in two clinical trials investigating tyrosine kinase inhibitors (TKI) discontinuation: STIM and STIM2. Results: After adjustment for standard risk factors in CML, we found that the inhibitory receptor KIR2DL5B‐positive genotype was independently related to a delayed second deep molecular remission (HR 0.54, 95% CI [0.32‐0.91], P = 0.02) after TKI rechallenge but not to time to first deep molecular remission or treatment‐free remission rates. Conclusion: These results suggest that KIR2DL5B could carry a role in lymphocyte‐mediated control of leukemic residual disease control in patient with CML relapse.

Poor prognosis of chromosome 7 clonal aberrations in Philadelphia-negative metaphases and relevance of potential underlying myelodysplastic features in chronic myeloid leukemia

Clonal chromosome abnormalities in Philadelphia-negative cells could concern chronic myeloid leukemia patients treated by tyrosine kinase inhibitors. The European LeukemiaNet distinguishes -7/del(7q) abnormalities as a “warning”. However, the impact of clonal chromosome abnormalities, and specifically those of -7/del(7q), in Philadelphia-negative cells on clinical outcomes is unclear and based on case-reports showing morphological dysplasia and increased risk of acute myeloid leukemia, suggesting the coexistence of chronic myeloid leukemia and high-risk myelodysplastic syndrome. The aim of this study was to determine whether the impact of -7/del(7q) clonal chromosome abnormalities in Philadelphia-negative cells on the clinical outcome is different from that of other types of abnormalities, and we argue for an underlying associated high-risk myelodysplastic syndrome. Among 102 chronic myeloid leukemia patients with clonal chromosome abnormalities in Philadelphia-negative cells with more than a median of 6 years of follow up, patients with -7/del(7q) more frequently had signs of dysplasia, a lower cumulative incidence of deep molecular response and often needed further treatment lines, with the consequent impact on event-free and progression-free survival. Morphological features of dysplasia are associated with myelodysplastic syndrome/acute myeloid leukemia mutations and compromise the optimal response to tyrosine kinase inhibitors, irrespectively of the type of clonal chromosome abnormalities in Philadelphia-negative cells. However, mutation patterns determined by next-generation sequencing could not clearly explain the underlying high-risk disease. We hereby confirm the pejorative prognostic value of -7/del(7q) clonal chromosome abnormalities in Philadelphia-negative cells and suggest that myelodysplastic features constitute a warning signal that response to tyrosine kinase inhibitors may be less than optimal.

Calibration of BCR-ABL1 mRNA quantification methods using genetic reference materials is a valid strategy to report results on the international scale

OBJECTIVES

Until recently, diagnostic laboratories that wanted to report on the international scale had limited options: they had to align their BCR-ABL1 quantification methods through a sample exchange with a reference laboratory to derive a conversion factor. However, commercial methods calibrated on the World Health Organization genetic reference panel are now available. We report results from a study designed to assess the comparability of the two alignment strategies.

DESIGN AND METHODS

Sixty follow-up samples from chronic myeloid leukemia patients were included. Two commercial methods calibrated on the genetic reference panel were compared to two conversion factor methods routinely used at Saint-Louis Hospital, Paris, and at Lille University Hospital. Results were matched against concordance criteria (i.e., obtaining at least two of the three following landmarks: 50, 75 and 90% of the patient samples within a 2-fold, 3-fold and 5-fold range, respectively).

RESULTS

Out of the 60 samples, more than 32 were available for comparison. Compared to the conversion factor method, the two commercial methods were within a 2-fold, 3-fold and 5-fold range for 53 and 59%, 89 and 88%, 100 and 97%, respectively of the samples analyzed at Saint-Louis. At Lille, results were 45 and 85%, 76 and 97%, 100 and 100%, respectively. Agreements between methods were observed in the four comparisons performed.

CONCLUSION

Our data show that the two commercial methods selected are concordant with the conversion factor methods. This study brings the proof of principle that alignment on the international scale using the genetic reference panel is compatible with the patient sample exchange procedure. We believe that these results are particularly important for diagnostic laboratories wishing to adopt commercial methods.

Matching-adjusted indirect comparison of asciminib versus other treatments in chronic-phase chronic myeloid leukemia after failure of two prior tyrosine kinase inhibitors

PURPOSE

The current standard of care for chronic-phase chronic myeloid leukemia (CP-CML) is tyrosine kinase inhibitors (TKIs). Treatment recommendations are unclear for CP-CML failing ≥ 2 lines of treatment, partly due to the paucity of head-to-head trials evaluating TKIs. Thus, matching-adjusted indirect comparisons (MAICs) were conducted to compare asciminib with competing TKIs in third- or later line (≥ 3L) CP-CML.

METHODS

Individual patient-level data for asciminib (ASCEMBL; follow-up: ≥ 48 weeks) and published aggregate data for comparator TKIs (ponatinib, nilotinib, and dasatinib) informed the analyses. Major molecular response (MMR), complete cytogenetic response (CCyR), and time to treatment discontinuation (TTD) were assessed, where feasible.

RESULTS

Asciminib was associated with statistically significant improvements in MMR by 6 (relative risk [RR]: 1.55; 95% confidence interval [CI]: 1.02, 2.36) and 12 months (RR: 1.48; 95% CI: 1.03, 2.14) vs ponatinib. For CCyR, the results vs ponatinib were similar by 6 (RR: 1.11; 95% CI: 0.81, 1.52) and 12 months (RR: 0.97; 95% CI: 0.73, 1.28). Asciminib was associated with improvements in MMR by 6 months vs dasatinib but with a CI overlapping one (RR 1.52; 95% CI: 0.66, 3.53). Asciminib was associated with statistically significant improvements in CCyR by 6 (RR: 3.57; 95% CI: 1.42, 8.98) and 12 months (RR: 2.03; 95% CI: 1.12, 3.67) vs nilotinib/dasatinib. Median TTD was unreached for asciminib in ASCEMBL. However, post-adjustment asciminib implied prolonged TTD vs nilotinib and dasatinib, but not vs ponatinib.

CONCLUSION

These analyses demonstrate favorable outcomes with asciminib versus competing TKIs, highlighting its therapeutic potential in ≥ 3L CP-CML.

A multicenter, randomized phase III study of asciminib (ABL001) versus bosutinib in patients (pts) with chronic myeloid leukemia in chronic phase (CML-CP) previously treated with ≥2 tyrosine kinase inhibitors (TKIs)

TPS7070

Background: There is a need for new treatment options for pts with CML who are intolerant/resistant to currently available BCR-ABL1 ATP-binding site targeted TKIs. Asciminib is a potent and specific BCR-ABL1 inhibitor with a novel allosteric mechanism of action targeting the ABL1 myristoyl pocket. This results in a mutation-driven resistance profile different from that of ATP binding-site TKIs, providing potential for both monotherapy and combination therapy with ATP-binding-site TKIs. In a phase 1 study (NCT02081378), asciminib showed clinical activity and good safety/tolerability in CML pts with resistance/intolerance to ≥2 TKIs and in pts with the T315I mutation. The recommended dose for asciminib monotherapy in CML pts without the T315I mutation was established as 40 mg BID. An ongoing phase 3 study (NCT03106779) is evaluating asciminib monotherapy vs bosutinib in pts with CML who have been treated with ≥2 prior ATP-binding-site TKIs. Methods: Eligible pts are adults with CML-CP who previously received ≥2 TKIs, with intolerance or failure to the most recent TKI. Treatment failure is defined per 2013 European LeukemiaNet (ELN) recommendations. Pts harboring T315I or V299L mutations are excluded. Pts are randomized 2:1 – stratified by baseline cytogenetic response status – to receive asciminib 40 mg BID or bosutinib 500 mg QD (planned enrollment: N = 222). Primary and key secondary objectives are to compare the rate of major molecular response ( BCR-ABL1IS≤0.1%) with asciminib vs bosutinib at 24 and 96 weeks, respectively. In a recent protocol amendment, the baseline BCR-ABL1IS threshold for enrollment was lowered from ≥1% to > 0.1% for pts with intolerance to the most recent TKI. This change was implemented to align with clinical practice and satisfy the treatment need to avoid waiting for an increase in BCR-ABL1IS levels to ≥1%. In addition, pts with documented bosutinib treatment failure as per ELN recommendations may switch to receive asciminib therapy at any time, as such pts may have limited treatment options outside of this study. This study is ongoing with 149 participating study sites in 30 countries. Clinical trial information: NCT03106779.