Efficacy of Ponatinib Versus Earlier Generation Tyrosine Kinase Inhibitors for Front-line Treatment of Newly Diagnosed Philadelphia-positive Acute Lymphoblastic Leukemia

Ponatinib-review of historical development, current status, and future research

Ponatinib is a third-generation BCR::ABL1 tyrosine kinase inhibitor (TKI) with high potency against Philadelphia chromosome (Ph)-positive leukemias, including T315I-mutated disease, which is resistant to first- and second-generation TKIs. Ponatinib was approved for T315I-mutated chronic myeloid leukemia (CML), CML resistant/intolerant to ≥2 prior TKIs, advanced phase CML and Ph-positive acute lymphoblastic leukemia (ALL) where no other TKIs are indicated, and T315I-mutated CML and Ph-positive ALL. The response-based dosing of ponatinib in chronic phase CML (CP-CML) improved treatment tolerance and reduced the risk of toxicities, including cardiovascular risks. Ponatinib-based therapy also resulted in significantly better outcomes in frontline Ph-positive ALL compared with prior TKIs and is becoming a new standard of care in this setting. As the clinical development of third-generation TKIs and their rational combinations progresses, we envision further transformative changes in the treatment of CML and Ph-positive ALL.

Is intensive chemotherapy and allogeneic stem cell transplantation mandatory for curing Philadelphia chromosome-positive acute lymphoblastic leukemia in young patients in the era of multitarget agents?

INTRODUCTION

The treatment outcomes for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) have improved with various tyrosine kinase inhibitors (TKIs) and bispecific T-cell engagers. Although allogeneic stem cell transplantation (allo-SCT) is the standard treatment for young patients with Ph+ALL, its role remains debatable in the era of TKIs and blinatumomab.

AREAS COVERED

There are some issues regarding Ph+ALL. First, do young patients require intensive chemotherapy (IC) in the era of multitarget agents? Second, which TKI is preferred for frontline therapy? Third, should allo-SCT be performed in patients achieving complete remission with ponatinib and IC? Fourth, can chemo-free treatment lead to a cure without allo-SCT? We searched relevant literature from the last 30 years on PubMed; reviewed the role of chemo-free therapies and combinations of ponatinib and IC; and assessed the necessity of allo-SCT in young patients with Ph+ALL.

EXPERT OPINION

Allo-SCT may not be needed, even in young patients with Ph+ALL treated with ponatinib-based IC or combined ponatinib and blinatumomab as frontline therapy. When adopting a ponatinib-based chemo-minimized regimen for induction, allo-SCT is needed with posttransplant ponatinib maintenance. Continuous exposure to ponatinib at pre- or post-transplant is regarded as one of the most important factor for the success of treatment.

Management of ALL in adults: 2024 ELN recommendations from a European expert panel

ABSTRACT

Experts from the European Leukemia Net (ELN) working group for adult acute lymphoblastic leukemia have identified an unmet need for guidance regarding management of adult acute lymphoblastic leukemia (ALL) from diagnosis to aftercare. The group has previously summarized their recommendations regarding diagnostic approaches, prognostic factors, and assessment of ALL. The current recommendation summarizes clinical management. It covers treatment approaches, including the use of new immunotherapies, application of minimal residual disease for treatment decisions, management of specific subgroups, and challenging treatment situations as well as late effects and supportive care. The recommendation provides guidance for physicians caring for adult patients with ALL which has to be complemented by regional expertise preferably provided by national academic study groups.

How I treat newly diagnosed acute lymphoblastic leukemia

Treatment algorithms differ for adult patients with Philadelphia-negative (Ph-) and Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL). For Ph- ALL intensive induction-consolidation chemotherapy using "pediatric-inspired" protocols is a standard of care. Allogeneic hematopoietic cell transplantation (allo-HCT) from either an HLA-matched sibling, unrelated or haploidentical donor should be considered for patients with high estimated risk of relapse. Inadequate response at the level of measurable residual disease (MRD) is the strongest adverse prognostic factor. Patients with B-ALL and detectable MRD should be treated with blinatumomab. In the future, the use of blinatumomab and/or inotuzumab ozogamycin in addition to first-line chemotherapy may become a new standard of care reducing the role of allo-HCT. For patients with Ph+ ALL, tyrosine kinase inhibitors (TKI) are the most important components of treatment protocols, while the intensity of chemotherapy may be reduced. Allo-HCT is recommended for all patients treated with imatinib along with low-intensity chemotherapy. Results of phase-II studies using front-line dasatinib or ponatinib in sequence or in combination with blinatumomab are very promising. Such a strategy may allow the avoidance of systemic chemotherapy. The future role of allo-HCT in this context appears uncertain.

Case report: Olverembatinib monotherapy: the chemotherapy-free regimen for an elderly patient with relapsed Ph-positive acute lymphoblastic leukemia

Background: The advent of first- and second-generation BCR/ABL1 tyrosine kinase inhibitors (TKIs), such as imatinib and dasatinib, has markedly improved the clinical outcomes of patients with philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+-ALL). However, due to acquired drug resistance, most Ph+-ALL patients experience relapse. Thus, third-generation BCR/ABL1 TKIs, including ponatinib and olverembatinib, have been developed with the aim of overcoming drug resistance. Case report: A 79-year-old woman presented with intermittent fever and fatigue for 4 days. After comprehensive cytogenetic examination, the patient was diagnosed with Ph+-B-ALL. Starting on 22 September 2021, a combined regimen of flumatinib and vincristine/prednisone (VP) was administered for seven cycles, followed by flumatinib maintenance therapy. The patient remained in first complete molecular remission (1st CMR) for 19 months. On 12 March 2023, she again complained of fatigue and loss of appetite for nearly a month. A comprehensive examination showed Ph+-B-ALL relapse with additional E255V mutation, although T315I mutation was negative. In view of her frail physical condition, she received olverembatinib monotherapy and achieved second CMR (second CMR). No severe toxicities were recorded except for mild fatigue. At present, she has been in second CMR for over 6 months. Conclusion: For elderly patients with relapsed Ph+-ALL, olverembatinib monotherapy may offer a novel option with a good safety profile, suggesting the feasibility of a chemo-free regimen.

Effect of the tyrosine kinase inhibitors on the growth in children with Philadelphia chromosome-positive acute lymphoblastic leukemia: a case-control study

Background

First-generation ABL-targeted tyrosine kinase inhibitor (TKI) imatinib is known to retard growth in children but it is not known if the second-generation ABL-targeted TKI dasatinib has the same effect. We aimed to determine the impact of the first- or second-generation TKI on the growth of children treated for Philadelphia chromosome-positive (Ph+) childhood acute lymphoblastic leukemia (ALL).

Methods

We evaluated the longitudinal growth changes in 140 children with Ph+ ALL treated with imatinib or dasatinib in additional to intensive cytotoxic chemotherapy and 280 matched controls treated with the same intensity of cytotoxic chemotherapy without TKI on Chinese Children's Cancer Group ALL-2015 protocol between 2015 and 2019. We retrospectively reviewed the height data obtained during routine clinic visits at 4 time points: at diagnosis, the end of therapy, 1 year and 2 years off therapy. Height z Scores were derived with the aid of WHO Anthro version 3.2.2 and WHO AnthroPlus version 1.0.4, global growth monitoring tool.

Findings

This study consisted only patients who have completed all treatment in continuous complete remission without major events, including 33 patients randomized to receive imatinib, 43 randomized to receive dasatinib, and 64 assigned to receive dasatinib. Similar degree of loss of height z scores from diagnosis to the end of therapy was observed for the 33 imatinib- and the 107 dasatinib-treated patients (median △ = -0.84 vs. -0.88, P = 0.41). Adjusting for height z score at diagnosis, puberty status, and sex, there was no significant difference in the longitudinal mean height z scores between patients treated with imatinib and those with dasatinib (0.08, 95% CI, -0.22 to 0.38, P = 0.60). The degree of loss of height z scores from diagnosis to end of therapy was significantly greater in the 140 TKI-treated patients than the 280 controls (median △ = -0.88 vs. -0.18, P < 0.001). The longitudinal mean height z scores in the TKI-treated patients were significantly lower than those of the controls (-0.84, 95% CI, -0.98 to -0.69; P < 0.001).

Interpretation

These data suggest that dasatinib and imatinib have the similar adverse impact on the growth of children with Ph+ ALL.

Funding

This study was supported by the National Natural Science Foundation of China (grant 81670136 [JCai and JT]), the fourth round of Three-Year Public Health Action Plan (2015-2017; GWIV-25 [SS]), Shanghai Health Commission Clinical Research Project (202140161 [JCai]), the US National Cancer institute (CA21765 [C-H Pui]), and the American Lebanese Syrian Associated Charities (CC, JJY, and C-HP). The content of this paper is solely the responsibility of the authors and does not necessarily represent the official views of the US National Institutes of Health.

Management of Philadelphia chromosome positive acute lymphoblastic leukemia in the current era

Before the advent of tyrosine kinase inhibitors (TKI) the outcome of Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL) was dismal. The TKI combination with induction regimens has greatly improved the long-term outcome of Ph+ ALL, specifically ponatinib a most potent TKI in combination with HyperCVAD (hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone) chemotherapy has demonstrated 5 years overall survival up to 75%. Historically, allogeneic hematopoietic stem cell transplantation (allo-HSCT) used to be the only potential curative option, recent data suggest that patients who achieve complete molecular remission within 3 months of TKI based induction therapies can achieve comparable overall survival with or without allo-HSCT. Intensive cytotoxic chemotherapy may not be the desirable treatment option in elderly Ph+ ALL patients due to anticipated tolerance, recently in a phase II study, "chemotherapy free" combinations such as blinatumomab (bispecific anti-CD3 and anti-CD19 monoclonal antibody) with ponatinib in treatment naïve Ph+ ALL patients have shown a complete response rate of 95% and 2 years overall survival of 93%. In this review we have highlighted the evolving treatment landscape of Ph+ ALL and what to look for in future.

The evolution of acute lymphoblastic leukemia research and therapy at MD Anderson over four decades

Progress in the research and therapy of adult acute lymphoblastic leukemia (ALL) is accelerating. This analysis summarizes the data derived from the clinical trials conducted at MD Anderson between 1985 and 2022 across ALL subtypes. In Philadelphia chromosome-positive ALL, the addition of BCR::ABL1 tyrosine kinase inhibitors (TKIs) to intensive chemotherapy since 2000, improved outcomes. More recently, a chemotherapy-free regimen with blinatumomab and ponatinib resulted in a complete molecular remission rate of 85% and an estimated 3-year survival rate of 90%, potentially reducing the role of, and need for allogeneic stem cell transplantation (SCT) in remission. In younger patients with pre-B Philadelphia chromosome-negative ALL, the integration of blinatumomab and inotuzumab into the frontline therapy has improved the estimated 3-year survival rate to 85% across all risk categories. Our future strategy is to evaluate the early integration of both immunotherapy agents, inotuzumab and blinatumomab, with low-dose chemotherapy (dose-dense mini-Hyper-CVD-inotuzumab-blinatumomab) into the frontline setting followed by CAR T cells consolidation in high-risk patients, without any further maintenance therapy. In older patients, using less intensive chemotherapy (mini-Hyper-CVD) in combination with inotuzumab and blinatumomab has improved the 5-year survival rate to 50%. Among patients ≥ 65-70 years, the mortality in complete remission (CR) is still high and is multifactorial (old age, death in CR with infections, development of myelodysplastic syndrome or acute myeloid leukemia). A chemotherapy-free regimen with inotuzumab and blinatumomab is being investigated. The assessment of measurable residual disease (MRD) by next-generation sequencing (NGS) is superior to conventional assays, with early MRD negativity by NGS being associated with the best survival. We anticipate that the future therapy in B-ALL will involve less intensive and shorter chemotherapy regimens in combination with agents targeting CD19 (blinatumomab), CD20, and CD22 (inotuzumab). The optimal timing and use of CAR T cells therapy may be in the setting of minimal disease, and future trials will assess the role of CAR T cells as a consolidation among high-risk patients to replace allogeneic SCT. In summary, the management of ALL has witnessed significant progress during the past four decades. Novel combination regimens including newer-generation BCR::ABL1 TKIs and novel antibodies are questioning the need and duration of intensive chemotherapy and allogeneic SCT.

Chemotherapy with the use of next-generation TKIs based on MRD has the potential to avoid hematopoietic stem cell transplantation in treatment for adults with Philadelphia chromosome-positive acute lymphoblastic leukemia

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) as postremission treatment is recommended for Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL) in current guidelines. However, comparisons of later generation tyrosine kinase inhibitors (TKIs) plus chemotherapy with allo-HSCT have yielded similar outcomes. This meta-analysis was performed to evaluate allo-HSCT in first complete remission (CR1) versus chemotherapy for adult Ph+ ALL in the TKI era.

METHODS

Pooled assessment of the hematologic and molecular complete response rates was performed after 3-month TKI treatment. Hazard ratios (HRs) were determined for disease-free survival (DFS) and overall survival (OS) benefit with allo-HSCT. The effect of measurable residual disease status on survival benefit was also analyzed.

RESULTS

Thirty-nine retrospective and prospective single-arm cohort studies involving 5054 patients were included. Combined HRs indicated that in the general population, allo-HSCT favorably influenced DFS and OS. Achieving complete molecular remission (CMR) within 3 months after starting induction was a favorable survival prognostic factor regardless of whether the patient had undergone allo-HSCT. Among the patients with CMR, survival rates in the nontransplant subgroup were comparable with those in the transplant subgroup, with the estimated 5-year OS of 64% versus 58% and 5-year DFS of 58% versus 51%, respectively. The use of next-generation TKIs results in a higher proportion of patients achieving CMR (ponatinib 82% vs. imatinib 53%), while improving survival in nontransplant patients.

CONCLUSION

Our novel findings suggest that combination chemotherapy plus TKIs leads to a comparable survival benefit as with allo-HSCT for MRD-negative (CMR) patients. This study provides novel evidence for allo-HSCT indications for Ph+ ALL in CR1 in the TKI era.

ERBB1/EGFR and JAK3 Tyrosine Kinases as Potential Therapeutic Targets in High-Risk Multiple Myeloma

Our main objective was to identify abundantly expressed tyrosine kinases in multiple myeloma (MM) as potential therapeutic targets. We first compared the transcriptomes of malignant plasma cells from newly diagnosed MM patients who were risk-categorized based on the patient-specific EMC-92/SKY-92 gene expression signature values vs. normal plasma cells from healthy volunteers using archived datasets from the HOVON65/GMMG-HD4 randomized Phase 3 study evaluating the clinical efficacy of bortezomib induction/maintenance versus classic cytotoxic drugs and thalidomide maintenance. In particular, ERBB1/EGFR was significantly overexpressed in MM cells in comparison to normal control plasma cells, and it was differentially overexpressed in MM cells from high-risk patients. Amplified expression of EGFR/ERBB1 mRNA in MM cells was positively correlated with increased expression levels of mRNAs for several DNA binding proteins and transcription factors with known upregulating activity on EGFR/ERBB1 gene expression. MM patients with the highest ERBB1/EGFR expression level had significantly shorter PFS and OS times than patients with the lowest ERBB1/EGFR expression level. High expression levels of EGFR/ERBB1 were associated with significantly increased hazard ratios for unfavorable PFS and OS outcomes in both univariate and multivariate Cox proportional hazards models. The impact of high EGFR/ERBB1 expression on the PFS and OS outcomes remained significant even after accounting for the prognostic effects of other covariates. These results regarding the prognostic effect of EGFR/ERBB1 expression were validated using the MMRF-CoMMpass RNAseq dataset generated in patients treated with more recently applied drug combinations included in contemporary induction regimens. Our findings provide new insights regarding the molecular mechanism and potential clinical significance of upregulated EGFR/ERBB1 expression in MM.

Tyrosine kinases in KMT2A/MLL-rearranged acute leukemias as potential therapeutic targets to overcome cancer drug resistance

Aim: The main goal of this study was to elucidate at the transcript level the tyrosine kinase expression profiles of primary leukemia cells from mixed lineage leukemia 1 gene rearranged (KMT2A/MLL-R⁺) acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) patients. Methods: We evaluated protein tyrosine kinase (PTK) gene expression profiles of primary leukemic cells in KMT2A/MLL-R⁺ AML and ALL patients using publicly available archived datasets. Results: Our studies provided unprecedented evidence that the genetic signatures of KMT2A/MLL-R⁺ AML and ALL cells are characterized by transcript-level overexpression of specific PTK. In infants, children and adults with KMT2A/MLL-R⁺ ALL, as well as pediatric patients with KMT2A/MLL-R⁺ AML, the gene expression levels for FLT3, BTK, SYK, JAK2/JAK3, as well as several SRC family PTK were differentially amplified. In adults with KMT2A/MLL-R⁺ AML, the gene expression levels for SYK, JAK family kinase TYK2, and the SRC family kinases FGR and HCK were differentially amplified. Conclusion: These results provide new insights regarding the clinical potential of small molecule inhibitors of these PTK, many of which are already FDA/EMA-approved for other indications, as components of innovative multi-modality treatment platforms against KMT2A/MLL-R⁺ acute leukemias.

Real world outcomes in patients with Philadelphia chromosome positive acute lymphoblastic leukemia undergoing allogeneic stem cell transplantation-A single institution experience

Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL) has been associated with a worse prognosis compared to Ph negative ALL. Tyrosine kinase inhibitor (TKI) therapy has led to an improvement in response rates and survival, thus becoming a critical component of therapy. We performed a retrospective cohort study of Ph+ ALL patients treated at the University of Michigan who received TKI therapy pre- and post-allogeneic hematopoietic stem cell transplant (HSCT) from April 2007 to November 2019. The study included 40 patients with Ph+ ALL (47.5% female) with a median age of 54 (24-69) years. Median event-free survival (EFS) was not reached, with a 5-year EFS of 61%. Median overall survival (OS) was not reached, with a 5-year OS of 71%. There was no difference in 2-year EFS or OS for patients on pre-transplant imatinib or dasatinib (p = 0.16, 0.09, respectively), though definitive conclusions are challenging as post-transplant TKI therapy was variable. The incidence of any grade acute graft-versus-host disease (GVHD) was 62.5% (25/40) and any grade chronic GVHD was 77.5% (31/40). Complete molecular remission (CMR) was achieved in 57.5% of patients pre-transplant with no significant difference when stratified by induction TKI (p = 1). Achievement of CMR pre-HSCT showed a trend towards improved 2-year EFS (p=0.0198) but did not significantly change 2-year OS (p = 1). Patients receiving 1^st and 2^nd generation TKIs pre- and post-HSCT seem to have favorable outcomes, although type of TKI (pre-HSCT) did not significantly impact EFS or OS. In addition, attaining a CMR pre-transplant improved EFS, but did not change OS.

Treatment of Adults With Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia-From Intensive Chemotherapy Combinations to Chemotherapy-Free Regimens: A Review

Importance

With the advent of potent BCR::ABL1 tyrosine kinase inhibitors (TKIs), Philadelphia chromosome-positive (Ph-positive) acute lymphoblastic leukemia (ALL) is now a relatively favorable-risk acute leukemia. In this review, we discuss the current evidence for frontline therapies of Ph-positive ALL, the major principles that guide therapy, and the progress with chemotherapy-free regimens.

Observations

Incorporating TKIs into the chemotherapy regimens of patients with newly diagnosed Ph-positive ALL has led to improved remission rates, higher probability of reaching allogeneic stem cell transplantation (SCT), and longer survival compared with chemotherapy alone. Early achievement of a complete molecular remission (CMR) is an important end point in Ph-positive ALL and identifies patients who have excellent long-term survival and may not need allogeneic SCT. Second-generation TKIs combined with intensive or low-intensity chemotherapy resulted in higher CMR rates compared with imatinib-based regimens. This translated into better outcomes, with less reliance on allogeneic SCT. To further improve the outcomes, the potent third-generation TKI ponatinib was added to chemotherapy. The combination of hyper-CVAD and ponatinib resulted in an overall CMR rate of 84% and a 5-year survival rate of 73% and 86% among patients who did and did not undergo allogeneic SCT, respectively, suggesting that allogeneic SCT may not be needed with this regimen. The recent chemotherapy-free combination of dasatinib and blinatumomab was safe and effective in patients with newly diagnosed Ph-positive ALL and resulted in an estimated 3-year OS rate of 80%; 50% of patients underwent allogeneic SCT. The chemotherapy-free regimen of ponatinib and blinatumomab resulted in a CMR rate of 86% and a 2-year survival rate of 93%, with no relapses or leukemia-related deaths, and with only 1 patient proceeding to allogeneic SCT.

Conclusions and Relevance

The promising results obtained with the chemotherapy-free regimens of blinatumomab plus TKIs question the role of allogeneic SCT in first remission. Patients with Ph-positive ALL who achieve early and deep molecular responses have excellent long-term outcomes and may not benefit from allogeneic SCT.

The current treatment approach to adolescents and young adults with acute lymphoblastic leukemia (AYA-ALL): challenges and considerations

INTRODUCTION

AYA-ALL differs from pediatric ALL in terms of clinical, biological, psychosocial factors and access to care and has an inferior outcome. It is now being recognized that pediatric-inspired protocols are superior to adult protocols for this cohort, but given the lack of randomized trials, several questions remain unanswered.

AREAS COVERED

In this review, we discuss how AYA-ALL is different from the pediatric ALL population, compare AYA ALL with ALL in middle and older age adults, review the studies that have enrolled the AYA cohort, summarize risk-stratified and response-adapted approaches, describe the biological subtypes, and review the novel agents/approaches under evaluation.

EXPERT OPINION

AYA-ALL is a complex and challenging disease that needs multidisciplinary and focused care. Well-designed clinical trials that focus on this cohort are needed to further improve the outcomes.

Targeting Apoptosis Pathways With BCL2 and MDM2 Inhibitors in Adult B-cell Acute Lymphoblastic Leukemia

In adult patients, the treatment outcome of acute lymphoblastic leukemia (ALL) remains suboptimal. Here, we used an ex vivo drug testing platform and comprehensive molecular profiling to discover new drug candidates for B-ALL. We analyzed sensitivity of 18 primary B-ALL adult patient samples to 64 drugs in a physiological concentration range. Whole-transcriptome sequencing and publicly available expression data were used to examine gene expression biomarkers for observed drug responses. Apoptotic modulators targeting BCL2 and MDM2 were highly effective. Philadelphia chromosome–negative (Ph–) samples were sensitive to both BCL2/BCL-W/BCL-XL-targeting agent navitoclax and BCL2-selective venetoclax, whereas Ph-positive (Ph+) samples were more sensitive to navitoclax. Expression of BCL2 was downregulated and BCL-W and BCL-XL upregulated in Ph+ ALL compared with Ph– samples, providing elucidation for the observed difference in drug responses. A majority of the samples were sensitive to MDM2 inhibitor idasanutlin. The regulatory protein MDM2 suppresses the function of tumor suppressor p53, leading to impaired apoptosis. In B-ALL, the expression of MDM2 was increased compared with other hematological malignancies. In B-ALL cell lines, a combination of BCL2 and MDM2 inhibitor was synergistic. In summary, antiapoptotic proteins including BCL2 and MDM2 comprise promising targets for future drug studies in B-ALL.

Patient preferences for frontline therapies for Philadelphia chromosome-positive acute lymphoblastic leukemia: a discrete choice experiment

Aim: We examined the preferences of adults with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) for benefits and risks of tyrosine kinase inhibitors combined with chemotherapy for first-line treatment. Methods: In a discrete choice experiment, 201 patients chose between hypothetical treatment alternatives with varied levels of remission duration and overall survival (OS), and risks of major cardiovascular (CV) events and myelosuppression. Results: Although OS was the most important attribute to patients with Ph+ ALL, they were willing to tolerate a 2.9% increase in CV risk for 1 additional month of OS. Older patients (>59 years) and patients not in remission were less likely to tolerate increased CV risk. Conclusion: Preferences and risk tolerance varied between patients, highlighting the importance of shared decision making when selecting treatments for Ph+ ALL.

The cure of leukemia through the optimist's prism

Progress is occurring at a dizzying rate across all leukemias. Since the authors' review of the topic in Cancer in 2018, numerous discoveries have been made that have improved the therapy and outcomes of several leukemia subsets. Hairy cell leukemia is potentially curable with a single course of cladribine followed by rituximab (10-year survival, ≥90%). Acute promyelocytic leukemia is curable at a rate of 80% to 90% with a nonchemotherapy regimen of all-trans retinoic acid and arsenic trioxide. The cure rate for core-binding factor acute myeloid leukemia (AML) is ≥75% with fludarabine, high-dose cytarabine, and gemtuzumab ozogamicin. Survival for patients with chronic myeloid leukemia is close to that for an age-matched normal population with BCR-ABL1 tyrosine kinase inhibitors (TKIs). Chronic lymphocytic leukemia, a previously incurable disease, may now be potentially curable with a finite duration of therapy with Bruton tyrosine kinase inhibitors and venetoclax. The estimated 5-year survival rate for patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL) exceeds 70% with intensive chemotherapy and ponatinib, a third-generation BCR-ABL1 TKI, and more recent nonchemotherapy regimens using dasatinib or ponatinib with blinatumomab are producing outstanding results. Survival in both younger and older patients with ALL has improved with the addition of antibodies targeting CD20, CD19 (blinatumomab), and CD22 (inotuzumab) to chemotherapy. Several recent drug discoveries (venetoclax, FLT3 and IDH inhibitors, and oral hypomethylating agents) are also improving outcomes for younger and older patients with AML and for those with higher risk myelodysplastic syndrome.

SOHO State of the Art Updates & Next Questions: Intensive and Non-Intensive Approaches for Adults With Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia

Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) was historically considered to be a very poor-risk subtype of ALL. However, with the introduction of highly potent BCR-ABL tyrosine kinase inhibitors (TKIs), Ph+ ALL can now be considered relatively favorable-risk acute leukemia. Considering the high rates of measurable residual disease negativity and excellent long-term survival that has been achieved with regimens incorporating later-generation TKIs and particularly with ponatinib, lower-intensity and even chemotherapy-free regimens are now being evaluated for patients of all ages with Ph+ ALL. The very encouraging early results observed with blinatumomab-based, chemotherapy-free regimens challenge previous notions that all patients with Ph+ ALL should undergo allogeneic stem cell transplantation in first remission, as these regimens are capable of achieving deep and durable remissions without need for transplant in the vast majority of patients, particularly when combined with ponatinib. In this review, we discuss the evolving approach to the treatment of adults with newly diagnosed Ph+ ALL and the major principles that should guide therapy in this disease. We also review the rationale and data supporting the use of novel, chemotherapy-free regimens in Ph+ ALL, and how these approaches may soon become new standards of care.

Targeted Therapy in Acute Lymphoblastic Leukaemia

The last decade has seen a significant leap in our understanding of the wide range of genetic lesions underpinning acute lymphoblastic leukaemia (ALL). Next generation sequencing has led to the identification of driver mutations with significant implications on prognosis and has defined entities such as BCR-ABL-like ALL, where targeted therapies such as tyrosine kinase inhibitors (TKIs) and JAK inhibitors may play a role in its treatment. In Philadelphia positive ALL, the introduction of TKIs into frontline treatment regimens has already transformed patient outcomes. In B-ALL, agents targeting surface receptors CD19, CD20 and CD22, including monoclonal antibodies, bispecific T cell engagers, antibody drug conjugates and chimeric antigen receptor (CAR) T cells, have shown significant activity but come with unique toxicities and have implications for how treatment is sequenced. Advances in T-ALL have lagged behind those seen in B-ALL. However, agents such as nelarabine, bortezomib and CAR T cell therapy targeting T cell antigens have been examined with promising results seen. As our understanding of disease biology in ALL grows, as does our ability to target pathways such as apoptosis, through BH3 mimetics, chemokines and epigenetic regulators. This review aims to highlight a range of available and emerging targeted therapeutics in ALL, to explore their mechanisms of action and to discuss the current evidence for their use.

Optimizing the treatment of acute lymphoblastic leukemia in younger and older adults: new drugs and evolving paradigms

In the past decade, the available treatments for patients with acute lymphoblastic leukemia (ALL) have rapidly expanded, in parallel with an increased understanding of the genomic features that impact the disease biology and clinical outcomes. With the development of the anti-CD22 antibody-drug conjugate inotuzumab ozogamicin, the CD3-CD19 bispecific T-cell engager antibody blinatumomab, CD19 chimeric antigen receptor T-cell therapy, and the potent BCR-ABL1 tyrosine kinase inhibitor ponatinib, the outlook of ALL in both younger and older adults has substantially improved. The availability of highly effective drugs raised important questions concerning the optimal combination and sequence of these agents, their incorporation into frontline regimens, and the role of hematopoietic stem cell transplantation. In this review, we discuss the rapidly evolving paradigms in the treatment of ALL, highlighting both established and effective regimens, as well as promising new therapies that are being evaluated in ongoing clinical trials. We specifically focus on novel combination regimens in both the frontline and salvage settings that are leading to new standards of care in the treatment of ALL.

Impact of frontline treatment approach on outcomes of myeloid blast phase CML

Background

The natural course of untreated chronic myeloid leukemia (CML) is progression to an aggressive blast phase. Even in the current era of BCR-ABL1 tyrosine kinase inhibitors (TKIs), the outcomes of blast phase CML remain poor with no consensus frontline treatment approach.

Methods

We retrospectively analyzed the response rates and survival outcomes of 104 consecutive patients with myeloid blast phase CML (CML-MBP) treated from 2000 to 2019 based on 4 different frontline treatment approaches: intensive chemotherapy (IC) + TKI (n = 20), hypomethylating agent (HMA) + TKI (n = 20), TKI alone (n = 56), or IC alone (n = 8). We also evaluated the impact of TKI selection and subsequent allogeneic stem cell transplant (ASCT) on patient outcomes.

Results

Response rates were similar between patients treated with IC + TKI and HMA + TKI. Compared to treatment with TKI alone, treatment with IC/HMA + TKI resulted in a higher rate of complete remission (CR) or CR with incomplete count recovery (CRi) (57.5% vs 33.9%, p < 0.05), a higher complete cytogenetic response rate (45% vs 10.7%, p < 0.001), and more patients proceeding to ASCT (32.5% vs 10.7%, p < 0.01). With a median follow-up of 6.7 years, long-term outcomes were similar between the IC + TKI and HMA + TKI groups. Combination therapy with IC/HMA + TKI was superior to therapy with TKI alone, including when analysis was limited to those treated with a 2nd/3rd-generation TKI. When using a 2nd/3rd-generation TKI, IC/HMA + TKI led to lower 5-year cumulative incidence of relapse (CIR; 44% vs 86%, p < 0.05) and superior 5-year event-free survival (EFS; 28% vs 0%, p < 0.05) and overall survival (OS; 34% vs 8%, p = 0.23) compared to TKI alone. Among patients who received IC/HMA + TKI, EFS and OS was superior for patients who received a 2nd/3rd generation TKI compared to those who received imatinib-based therapy. In a landmark analysis, 5-year OS was higher for patients who proceeded to ASCT (58% vs 22%, p = 0.12).

Conclusions

Compared to patients treated with TKI alone for CML-MBP, treatment with IC + TKI or HMA + TKI led to improved response rates, CIR, EFS, and OS, particularly for patients who received a 2nd/3rd-generation TKI. Combination therapy with IC + TKI or HMA + TKI, rather than a TKI alone, should be considered the optimal treatment strategy for patients with CML-MBP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-021-01106-1.

Optimal approach to the treatment of young adults with acute lymphoblastic leukemia in 2020

Akin to the introduction of tyrosine kinase inhibitors to Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL), pediatric-based asparaginase-heavy approaches have revolutionized the treatment of young adults with the Philadelphia chromosome-negative subset the past decades. Once again, we are approaching a new era. An era of precision medicine with immunotherapy and other molecularly targeted treatments that offers unique opportunities to customize treatment intensity with or without hematopoietic stem cell transplantation, reduce the burden of toxicities, and combat persistent residual disease. Recently approved agents for refractory/relapsed B-cell precursor ALL include the chimeric antigen receptor-modified T-cells, the anti-CD22 monoclonal antibody-drug conjugate, inotuzumab ozogamicin, and the bispecific anti-CD19 T-cell engager, blinatumomab. These agents are expected to move widely into the frontline setting along with the proteasome inhibitors, bortezomib and carfilzomib, as well as tyrosine kinase inhibitors for Philadelphia-like rearrangements that are especially frequent among young adults. To this add the BH3 mimetics, venetoclax and navitoclax, which are being widely explored in refractory/relapsed as well as frontline settings for B- and T-cell ALL. The promising anti-CD38 monoclonal antibody, daratumumab, is entering the scene of refractory/relapsed T-ALL, whereas the old purine analogue, nelarabine, is being evaluated in a new upfront setting. This review focuses on 2 main questions: How do we optimize frontline as well as salvage ALL treatment of young adults in the 2020s? Not least, how do we address the current burden of serious toxicities unique to young adults?

Philadelphia Chromosome-Positive Leukemia in the Lymphoid Lineage-Similarities and Differences with the Myeloid Lineage and Specific Vulnerabilities

Philadelphia chromosome (Ph) results from a translocation between the breakpoint cluster region (BCR) gene on chromosome 9 and ABL proto-oncogene 1 (ABL1) gene on chromosome 22. The fusion gene, BCR-ABL1, is a constitutively active tyrosine kinase which promotes development of leukemia. Depending on the breakpoint site within the BCR gene, different isoforms of BCR-ABL1 exist, with p210 and p190 being the most prevalent. P210 isoform is the hallmark of chronic myeloid leukemia (CML), while p190 isoform is expressed in majority of Ph-positive B cell acute lymphoblastic leukemia (Ph+ B-ALL) cases. The crucial component of treatment protocols of CML and Ph+ B-ALL patients are tyrosine kinase inhibitors (TKIs), drugs which target both BCR-ABL1 isoforms. While TKIs therapy is successful in great majority of CML patients, Ph+ B-ALL often relapses as a drug-resistant disease. Recently, the high-throughput genomic and proteomic analyses revealed significant differences between CML and Ph+ B-ALL. In this review we summarize recent discoveries related to differential signaling pathways mediated by different BCR-ABL1 isoforms, lineage-specific genetic lesions, and metabolic reprogramming. In particular, we emphasize the features distinguishing Ph+ B-ALL from CML and focus on potential therapeutic approaches exploiting those characteristics, which could improve the treatment of Ph+ B-ALL.

Hematopoietic Stem Cell Transplantation in Pediatric Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

The remarkable improvement in the prognosis of children with acute lymphoblastic leukemia (ALL) has been mainly achieved through the administration of risk-adapted therapy, including allogeneic hematopoietic stem cell transplantation (HSCT). This paper reviews the current indications to HSCT in ALL children, as well as the type of donor and conditioning regimens commonly used. Finally, it will focus on future challenges in immunotherapy.

RECENT FINDINGS

As our comprehension of disease-specific risk factors improves, indications to HSCT continue to evolve. Future studies will answer the year-old question on the best conditioning regimen to be used in this setting, while a recent randomized controlled study fixed the optimal anti-thymocyte globulin dose in unrelated donor HSCT. HSCT, the oldest immunotherapy used in clinical practice, still represents the gold standard consolidation treatment for a number of pediatric patients with high-risk/relapsed ALL. New immunotherapies hold the promise of further improving outcomes in this setting.

Evolving therapy of adult acute lymphoblastic leukemia: state-of-the-art treatment and future directions

Recent years have witnessed major advances that have improved outcome of adults with acute lymphoblastic leukemia (ALL). The emergence of the concept of measurable residual disease has fine-tuned our prognostic models and guided our treatment decisions. The treatment paradigms of ALL have been revolutionized with the advent of tyrosine kinase inhibitors targeting BCR-ABL1, monoclonal antibodies targeting CD20 (rituximab), antibody-drug conjugates targeting CD22 (inotuzumab ozogamicin), bispecific antibodies (blinatumomab), and CD19 chimeric antigen receptor T cell therapy (tisagenlecleucel). These highly effective new agents are allowing for novel approaches that reduce reliance on intensive cytotoxic chemotherapy and hematopoietic stem cell transplantation in first remission. This comprehensive review will focus on the recent advances and future directions in novel therapeutic strategies in adult ALL.

Evaluation and management of measurable residual disease in acute lymphoblastic leukemia

With standard chemotherapy regimens for adults with acute lymphoblastic leukemia, approximately 90% of patients achieve complete remission. However, up to half of patients have persistent minimal/measurable residual disease (MRD) not recognized by routine microscopy, which constitutes the leading determinant of relapse. Many studies in pediatric and adult populations have demonstrated that achievement of MRD negativity after induction chemotherapy or during consolidation is associated with significantly better long-term outcomes, and MRD status constitutes an independently prognostic marker, often superseding other conventional risk factors. Persistence of MRD after intensive chemotherapy is indicative of treatment refractoriness and warrants alternative therapeutic approaches including allogeneic stem cell transplantation, blinatumomab, or investigational therapies such as inotuzumab ozogamicin or chimeric antigen receptor T cells. Furthermore, the incorporation of novel monoclonal antibodies or potent BCR-ABL1 tyrosine kinase inhibitors, such as ponatinib into frontline treatment may have the advantage of achieving higher rates of MRD negativity while minimizing chemotherapy-related toxicities. Many studies are therefore ongoing to determine whether this strategy can improve cure rates without the need for allogeneic stem cell transplantation.

Curing Ph+ ALL: assessing the relative contributions of chemotherapy, TKIs, and allogeneic stem cell transplant

The understanding and treatment of Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia have changed rapidly in the past 10 years. The outcome is equally as good as for Ph- disease, and with targeted tyrosine kinase inhibitor therapies in addition to chemotherapy, the novel immunotherapy approaches, and the extension of allogeneic hematopoietic stem cell transplant (allo-HCT) to older individuals, there is the potential to exceed this outcome. There is particular interest in reducing chemotherapy exposure and considering for whom allo-HCT can be avoided. However, the patient population that can help test these options in clinical trials is limited in number, and the available evidence is often derived from single-arm studies. This paper summarizes outcomes achieved with recent approaches to de novo Ph+ acute lymphoblastic leukemia in the postimatinib era and helps integrate all the available information to assist the reader to make informed choices for patients in an increasingly complex field.

Philadelphia chromosome-positive acute lymphoblastic leukemia at first relapse in the era of tyrosine kinase inhibitors

Despite the advances in the management of Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) with the introduction of tyrosine kinase inhibitors (TKIs), relapses remain challenging. We reviewed clinical data from adult patients with Ph + ALL who received frontline hyperCVAD chemotherapy with a TKI to determine their outcomes after first relapse. Patients with first morphological relapse after prior complete remission were evaluated for predictors of response and survival. For 57 of 233 (25%) patients, there was morphological relapse after a median of 15.9 months from first remission [range: 5.3-94]. The choice of salvage treatments was at the discretion of the treating physician. So, 43 (75%) patients received a TKI in combination with their salvage treatment. Second remission was achieved in 41 of 49 (84%) evaluable patients. Median relapse free survival (RFS) was 10.5 months [range, 0.2-81]. The 1-year and 2-year overall survival (OS) were 41% and 20% respectively. On multivariate analysis, only elevated LDH (units/L), the use of first-generation or no TKI at the time of first relapse and the achievement of a major molecular response (MMR) had a significant effect on OS (HR: 2.82, 95% CI:1.11-7.16, P = .029; HR = 2.39, 95% CI: 1.07,5.39, P = .034; HR = 0.39, 95% CI: 0.16-0.94, P = .03, respectively). Whereas, only achievement of MMR was significantly prognostic for RFS with a HR of 0.48 (95% CI: 0.23-0.98, P = .04). The OS and RFS were comparable between recipients and non-recipients of allogeneic hematopoietic stem cell transplantation (alloHSCT) at second remission, due to a higher non-relapse mortality (53%) seen in patients who underwent alloHSCT.

Ponatinib in the Treatment of Chronic Myeloid Leukemia and Philadelphia Chromosome-Positive Acute Leukemia: Recommendations of a German Expert Consensus Panel with Focus on Cardiovascular Management

Treatment of chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute leukemia (Ph+ ALL) has been revolutionized with the advent of tyrosine kinase inhibitors (TKIs). Most patients with CML achieve long-term survival similar to individuals without CML due to treatment with TKIs not only in frontline but also in further lines of therapy. The third-generation TKI ponatinib has demonstrated efficacy in patients with refractory CML and Ph+ ALL. Ponatinib is currently the most potent TKI in this setting demonstrating activity against T315I mutant clones. However, ponatinib's safety data revealed a dose-dependent, increased risk of serious cardiovascular (CV) events. Guidance is needed to evaluate the benefit-risk profile of TKIs, such as ponatinib, and safety measures to prevent treatment-associated CV events. An expert panel of German hematologists and cardiologists summarize current evidence regarding ponatinib's efficacy and CV safety profile. We propose CV management strategies for patients who are candidates for ponatinib.

Targeted therapy paves the way for the cure of acute lymphoblastic leukaemia

The past decade has witnessed tremendous progress in the treatment of acute lymphoblastic leukaemia (ALL), primarily due to the development of targeted therapies, including tyrosine kinase inhibitors targeting BCR-ABL1 tyrosine kinase, monoclonal antibodies targeting cell surface antigens (CD19, CD20 and CD22), bispecific antibodies and chimeric antigen receptor T- cell therapy. A number of new therapies have been approved by the US Food and Drug Administration in the past 5 years, including blinatumomab in 2014, inotuzumab ozagamicin in 2017 and tisagenlecleucel in 2017 for relapsed/refractory ALL. This has led to tremendous improvement in long-term survival, of more than 50% in patients with precursor B-ALL [50-70% in patients with Philadelphia chromosome (Ph)-positive ALL)], 50-60% in T-ALL and 80% in mature B-ALL. Research is ongoing to optimize the benefit of targeted therapeutics with the goal of decreasing the use of cytotoxic therapies.

Treatment of Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia

OPINION STATEMENT

With the introduction of tyrosine kinase inhibitors (TKIs) in the management of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL), the prognosis of patients has improved dramatically. Currently, the standard of care in the frontline setting for fit patients is TKI in combination with chemotherapy. Age-adjusted chemotherapy or corticosteroids alone have been used with TKIs in elderly patients with comorbidities with modest long-term benefit. The primary goal of treatment is the achievement of early deep molecular remission as the achievement of complete molecular remission (CMR) at 3 months has been demonstrated to be predictive of higher long-term survival. The probability of attaining this goal by a more potent TKIs like dasatinib or ponatinib is higher, thus we recommend the use of second- or third-generation TKIs over imatinib. Clinicians should be aware of possible fatal cardiovascular events mainly related to ponatinib. Allogeneic hematopoietic stem cell transplantation (alloHSCT) should still be considered in first remission, especially for younger patients treated with imatinib combination therapy. A subset of patients achieving CMR at 3 months may be able to continue consolidation and maintenance with chemotherapy and TKI without the need for alloHSCT. Because of higher risk of relapses in the central nervous system, intrathecal chemoprophylaxis is mandatory for all patients. New strategies incorporating novel agents, such as antibody-drug conjugates, bispecific monoclonal antibodies, potent TKIs, and CAR T cells are under investigation.

The role of stem cell transplantation in the management of Philadelphia chromosome-positive acute lymphoblastic leukemia

The concurrent administration of tyrosine kinase inhibitors (TKIs) with standard chemotherapy together with allogeneic hematopoietic stem cell transplantation (alloHSCT) has improved the outcome of patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). Although to date, no study has shown alloHSCT to be inferior to chemotherapy plus TKIs in any subgroup of adult Ph+ ALL, there is some evidence suggesting no additional benefit of alloHSCT in patients with deep molecular responses to intensive chemotherapy with a second-generation, and especially, third-generation TKI. As none of these positive and negative studies are controlled, randomized trials are needed to fully define the role of alloHSCT in Ph+ ALL, especially in those with deep molecular response. However, if studies combining TKIs with new approaches such as immunotherapy lead to durable responses, alloHSCT in the first complete remission could be avoided in the near future in the majority of patients with Ph+ ALL.