FXa variants advance toward a therapy for bleeding

Cost-effectiveness analysis for midostaurin versus standard of care in acute myeloid leukemia in the United Kingdom

AIMS

Midostaurin (MIDO) has been proposed for the treatment of newly-diagnosed adult patients with FMS-like tyrosine kinase 3 mutation-positive (FLT3+) acute myeloid leukemia (AML) in combination with standard chemotherapy. The cost-effectiveness of MIDO and standard of care (SOC) followed by MIDO monotherapy was compared to SOC alone for newly-diagnosed FLT3+ AML in the UK.

METHODS

A partitioned survival model was developed from a UK public healthcare system perspective to compare the cost-effectiveness of MIDO plus SOC and SOC over a lifetime horizon. The model included the following health states/partitions: induction, consolidation, monotherapy, complete remission (CR), relapse, stem cell transplantation (SCT), SCT recovery, and post-SCT recovery. Data on CR, overall survival, and adverse events were obtained from a Phase III clinical trial. Overall survival was extrapolated beyond the trial horizon using a 'cure model' approach and data from the Office for National Statistics. Utilities were identified via a systematic review. Routine care utilization was obtained from the National Institute for Health and Care Excellence single technology appraisal for azacitidine in AML (TA399). The costs of drugs and administration, adverse events, hospitalizations, physician visits, and end-of-life care were incorporated.

RESULTS

Incremental life years (LYs) and quality-adjusted life years (QALYs) gained by patients on MIDO and SOC versus SOC were 1.67 and 1.47, respectively. At an incremental cost of £54,072 over a lifetime horizon, the ICER was £32,465 per LY and £36,826 per QALY. Sensitivity analyses were generally consistent with the base case findings.

CONCLUSIONS

With limited treatments in FLT3+ AML, MIDO represents a clinically significant advance in the management of newly-diagnosed AML. Using a threshold of £50,000 per QALY for end-of-life treatment, MIDO was shown to be a cost-effective option for newly-diagnosed FLT3+ AML.

Novel Therapies for Acute Myeloid Leukemia: Are We Finally Breaking the Deadlock?

Acute myeloid leukemia (AML) is one of the best studied malignancies, and significant progress has been made in understanding the clinical implications of its disease biology. Unfortunately, drug development has not kept pace, as the '7+3' induction regimen remains the standard of care for patients fit for intensive therapy 40 years after its first use. Temporal improvements in overall survival were mostly confined to younger patients and driven by improvements in supportive care and use of hematopoietic stem cell transplantation. Multiple forms of novel therapy are currently in clinical trials and are attempting to bring bench discoveries to the bedside to benefit patients. These novel therapies include improved chemotherapeutic agents, targeted molecular inhibitors, cell cycle regulators, pro-apoptotic agents, epigenetic modifiers, and metabolic therapies. Immunotherapies in the form of vaccines; naked, conjugated and bispecific monoclonal antibodies; cell-based therapy; and immune checkpoint inhibitors are also being evaluated in an effort to replicate the success seen in other malignancies. Herein, we review the scientific basis of these novel therapeutic approaches, summarize the currently available evidence, and look into the future of AML therapy by highlighting key clinical studies and the challenges the field continues to face.

Epidemiological, genetic, and clinical characterization by age of newly diagnosed acute myeloid leukemia based on an academic population-based registry study (AMLSG BiO)

We describe genetic and clinical characteristics of acute myeloid leukemia (AML) patients according to age from an academic population-based registry. Adult patients with newly diagnosed AML at 63 centers in Germany and Austria were followed within the AMLSG BiO registry (NCT01252485). Between January 1, 2012, and December 31, 2014, data of 3525 patients with AML (45% women) were collected. The median age was 65 years (range 18-94). The comparison of age-specific AML incidence rates with epidemiological cancer registries revealed excellent coverage in patients < 70 years old and good coverage up to the age of 80. The distribution according to the European LeukemiaNet (ELN) risk categorization from 2010 was 20% favorable, 31% intermediate-1, 28% intermediate-2, and 21% adverse. With increasing age, the relative but not the absolute prevalence of patients with ELN favorable and intermediate-1 risk (p < 0.001), with activating FLT3 mutations (p < 0.001), with ECOG performance status < 2 (p < 0.001), and with HCT-CI comorbidity index < 3 (p < 0.001) decreased. Regarding treatment, obesity and favorable risk were associated with an intensive treatment, whereas adverse risk, higher age, and comorbidity index > 0 were associated with non-intensive treatment or best supportive care. The AMLSG BiO registry provides reliable population-based distributions of genetic, clinical, and treatment characteristics according to age.

What are the most promising new agents in acute myeloid leukemia?

PURPOSE OF REVIEW

Although the treatment paradigm for acute myeloid leukemia (AML) had been largely unchanged for many years, in-depth molecular characterization has revolutionized our understanding of mutations that drive the disease, subsequently serving to guide current clinical investigation. Furthermore, recent advances in the field have highlighted the importance of optimizing known efficacious agents by improving drug delivery or bypassing resistance mechanisms. The current status of novel agents which are shaping the clinical management of AML patients are summarized in this review.

RECENT FINDINGS

Practice changing findings over the past year include improved overall survival (OS) in a molecularly defined AML subgroup as well as in elderly patients with secondary AML (sAML). Specifically, synergistic combination of daunorubicin and cytarabine (i.e., CPX-351) was found to improve OS in sAML patients. Furthermore, although multiple mutation specific inhibitors have been developed, optimal combination with additional agents appears critical, as monotherapies have not resulted in durable remissions or improved outcomes. Improved OS via the addition of midostaurin to intensive chemotherapy in FLT3 mutant AML supports this concept.

SUMMARY

For the first time in AML, personalized therapy has become possible through improved understanding of the molecular architecture and survival pathways of an individual's disease. The landscape of AML treatment is encouraging, with multiple novel agents likely to gain approval over the next 5 years.

Innovative strategies for adverse karyotype acute myeloid leukemia

PURPOSE OF REVIEW

Adverse karyotype acute myeloid leukemia is a disease particularly of older patients, but also observed in younger patients. Despite all efforts, standard chemotherapy is still generally applied in fit patients, as already for decades, and for nearly all different subtypes of acute myeloid leukemia. Lack of more specifically targeted therapy and the often older age of the patients are complicating treatment, and in the subgroup of patients achieving a complete remission, the strikingly high frequency of relapse is a characteristic of this disease. This review aims to give an overview of current treatment approaches as well as emerging therapies.

RECENT FINDINGS

Currently, the approach of a targeted therapy specific to the genetic and/or epigenetic aberrations detected in the individual patient is still not possible, and a 'one treatment fits all' course of action is still used, with allografting as curative consolidation. However, first immunotherapeutic approaches are emerging as treatment options and first phase 1 and 2 studies are described.

SUMMARY

Treatment of acute myeloid leukemia with adverse karyotype is still not individualized, most treatment options currently not being curative. This can change in the near future, but recent findings will have to be implemented into larger phase 3 studies before being standard of care.

The Future of Targeting FLT3 Activation in AML

Internal tandem duplications (ITD) and tyrosine-kinase domain (TKD) mutations of the FMS-like tyrosine-kinase 3 (FLT3) can be found in up to one third of patients with acute myeloid leukemia (AML) and confer a poor prognosis. First discovered 20 years ago, these mutations were identified as viable therapeutic targets, and FLT3 tyrosine-kinase inhibitors (TKIs) have been in development for the last decade with steadily increasing potency. However, FLT3-mutated AML often acquires resistance to the growing armamentarium of FLT3 inhibitors through a variety of mechanisms. In this review, we discuss the distinct clinical phenotype of FLT3-mutated AML, historically and currently available therapeutics, mechanisms of resistance, ongoing trials, and future outlook at treatment strategies.

State of the Art Update and Next Questions: Acute Myeloid Leukemia

As our general understanding regarding the complex nature of acute myeloid leukemia (AML) is expanding, so is our ability to translate this biological data into clinically relevant information. The use of whole genome and whole exome sequencing has begun to shed light on the importance of a variety of somatic mutations that are frequently identified in AML. In turn, this has allowed the field to incorporate mutational data into prognostic classifications which can guide treatment decisions. Furthermore, minimal residual disease (MRD) monitoring in AML is more commonplace as the prognostic relevance of MRD at various time points during treat is becoming clear. Many novel treatments have recently been approved, or are expected to gain approval in the near future, and this is opening the door to a more personalized approach to the management of AML.

Targeted therapies in Acute Myeloid Leukemia: a focus on FLT-3 inhibitors and ABT199

INTRODUCTION

Acute myeloid leukemia (AML) remains a therapeutic challenge. Despite ongoing research, the standard therapy for AML has not changed significantly in the past four decades. With the identification of cytogenetic and molecular abnormalities, several promising therapeutic agents are currently being investigated. FLT3 mutation is a well-recognized target seen in 30% of the cytogenetically normal AML. More recently, the BCL2 family of anti-apoptotic proteins have also generated great interest as a therapeutic target. Areas covered: This review will cover the role of FLT3 inhibitors in AML, discussing trials in relapsed/refractory AML and in the frontline setting, including the young and elderly patient population. Toxicities and potential mechanism of resistance will also be covered. In addition, most current studies demonstrating the role of BCL-2 inhibitors namely ABT-199/venetoclax in AML will also be discussed. Expert commentary: AML is one of the most heterogeneous group of hematological malignancies. It remains a therapeutic challenge with limited therapeutic progress despite ongoing research. With the identification of different mutations in AML, several drugs are being evaluated in clinical trials. Targeted agents such as FLT3 inhibitors and BH3 mimetics so far have shown promising results in terms of response and toxicity profile.

Treatment of Relapsed/Refractory Acute Myeloid Leukemia

OPINION STATEMENT

Approximately 40-45% of younger and 10-20% of older adults with acute myeloid leukemia (AML) will be cured with current standard chemotherapy. The outlook is particularly gloomy for patients with relapsed and/or refractory disease (cure rates no higher than 10%). Allogeneic hematopoietic stem cell transplantation (HSCT), the only realistic hope of cure for these patients, is an option for only a minority. In recent years, much has been learned about the genomic and epigenomic landscapes of AML, and the clonal architecture of both de novo and secondary AML has begun to be unraveled. These advances have paved the way for rational drug development as new "drugable" targets have emerged. Although no new drug has been approved for AML in over four decades, with the exception of gemtuzumab ozogamycin, which was subsequently withdrawn, there is progress on the horizon with the possible regulatory approval soon of agents such as CPX-351 and midostaurin, the Food and Drug Administration "breakthrough" designation granted to venetoclax, and promising agents such as the IDH inhibitors AG-221 and AG-120, the smoothened inhibitor glasdegib and the histone deacetylase inhibitor pracinostat. In our practice, we treat most patients with relapsed/refractory AML on clinical trials, taking into consideration their prior treatment history and response to the same. We utilize targeted sequencing of genes frequently mutated in AML to identify "actionable" mutations, e.g., in FLT3 or IDH1/2, and incorporate small-molecule inhibitors of these oncogenic kinases into our therapeutic regimens whenever possible. In the absence of actionable mutations, we rationally combine conventional agents with other novel therapies such as monoclonal antibodies and other targeted drugs. For fit patients up to the age of 65, we often use high-dose cytarabine-containing backbone regimens. For older or unfit patients, we prefer hypomethylating agent-based therapy. Finally, all patients with relapsed/refractory AML are evaluated for allogeneic HSCT.

Enhancing venetoclax activity in acute myeloid leukemia by co-targeting MCL1

Targeted therapies are frequently combined with standard cytotoxic drugs to enhance clinical response. Targeting the B-cell lymphoma 2 (BCL-2) family of proteins is an attractive option to combat chemoresistance in leukemia. Preclinical and clinical studies indicate modest single-agent activity with selective BCL-2 inhibitors (for example, venetoclax). We show that venetoclax synergizes with cytarabine and idarubicin to increase antileukemic efficacy in a TP53-dependent manner. Although TP53 deficiency impaired sensitivity to combined venetoclax and chemotherapy, higher-dose idarubicin was able to suppress MCL1 and induce cell death independently of TP53. Consistent with an MCL1-specific effect, cell death from high-dose idarubicin was dependent on pro-apoptotic Bak. Combining higher-dose idarubicin with venetoclax was able to partially overcome resistance in Bak-deficient cells. Using inducible vectors and venetoclax to differentially target anti-apoptotic BCL-2 family members, BCL-2 and MCL1 emerged as critical and complementary proteins regulating cell survival in acute myeloid leukemia. Dual targeting of BCL-2 and MCL1, but not either alone, prolonged survival of leukemia-bearing mice. In conclusion, our findings support the further investigation of venetoclax in combination with standard chemotherapy, including intensified doses of idarubicin. Venetoclax should also be investigated in combination with direct inhibitors of MCL1 as a chemotherapy-free approach in the future.

Phase 1 dose-escalating study to evaluate the safety, pharmacokinetics, and pharmacodynamics of a recombinant factor Xa variant (FXaI16L )

Essentials FXaI16L is a recombinant zymogen-like variant of activated coagulation factor X (FXa). A phase 1 dose escalation clinical trial of FXaI16L was conducted in healthy adults. FXaI16L was safe and tolerated at doses up to 5 μg/kg; no dose-limiting toxicity was observed. Data support further development of FXaI16L for patients with acute hemorrhagic conditions.

SUMMARY

Background FXaI16L (PF-05230907) is a zymogen-like variant of activated factor X (FXa). It shows enhanced resistance to inactivation by endogenous inhibitors as compared with wild-type FXa, and restores hemostatic activity in non-clinical models of various bleeding conditions. Objectives To evaluate the safety, pharmacokinetics and pharmacodynamics of FXaI16L by performing a phase 1, first-in-human, dose-escalation clinical trial in healthy adult volunteers. Methods Participants were assigned to one of six ascending single-dose cohorts (0.1, 0.3, 1, 2, 3 or 5 μg kg-1 ), each planned to comprise six volunteers treated with FXaI16L and two treated with placebo. Assessments included safety monitoring, pharmacokinetic and pharmacodynamic (PD) analyses, and immunogenicity testing. Results The trial enrolled 49 male volunteers. Administration of a single intravenous bolus dose of FXaI16L was safe and tolerated at all dose levels tested, with no dose-limiting toxicity or serious adverse events. FXaI16L plasma levels appeared to increase dose-proportionally, with a half-life of ~ 4 min. Treatment-related PD changes were observed for activated partial thromboplastin time, thrombin generation assay, thrombin-antithrombin complexes, prothrombin fragment 1 + 2, and D-dimer. One volunteer had a weak and transient non-neutralizing antidrug antibody response, which did not cross-react with native FX or native FXa. Conclusions FXaI16L was safe and tolerated, and showed a pharmacologic effect in healthy adults when administered at doses up to 5 μg kg-1 . The safety profile, pharmacokinetics and pharmacodynamics observed in this clinical trial support the further development of FXaI16L for hemostatic treatment in individuals with acute hemorrhagic conditions.

Preclinical Pharmacokinetics, Pharmacodynamics, Tissue Distribution, and Interspecies Scaling of Recombinant Human Coagulation Factor XaI16L

FXa^I16L is a recombinant human FXa variant which is currently being evaluated in the clinic for treating intracerebral hemorrhage. The aim of our studies is to investigate overall pharmacokinetics, pharmacodynamics, and distribution of FXa^I16L in preclinical species, and to understand its potential implication in human. Pharmacokinetics of FXa^I16L was examined using active site probes and the results showed that FXa^I16L displayed fast clearance, low volume of distribution, and a very short plasma resident time in mice, rats, and monkeys. When pharmacodynamics was examined in monkeys, concentration effects of FXa^I16L on shortening of active partial prothrombin time and formation of thrombin-antithrombin complex were observed. Furthermore, biodistribution study was conducted in mice using radiolabeled FXa^I16L, and showed that ¹²⁵I-FXa^I16L has high plasma protein binding and significant liver and kidney distribution. Human pharmacokinetic prediction for first-in-human dosing was evaluated using allometric scaling, liver blood flow, and a fixed coefficient method, and single species allometric scaling using monkey data was most predictive for human pharmacokinetics of FXa^I16L.

Harnessing the power of proteomics for identification of oncogenic, druggable signalling pathways in cancer

INTRODUCTION

Genomic and transcriptomic profiling of tumours has revolutionised our understanding of cancer. However, the majority of tumours possess multiple mutations, and determining which oncogene, or even which pathway, to target is difficult. Proteomics is emerging as a powerful approach to identify the functionally important pathways driving these cancers, and how they can be targeted therapeutically. Areas covered: The authors provide a technical overview of mass spectrometry based approaches for proteomic profiling, and review the current and emerging strategies available for the identification of dysregulated networks, pathways, and drug targets in cancer cells, with a key focus on the ability to profile cancer kinomes. The potential applications of mass spectrometry in the clinic are also highlighted. Expert opinion: The addition of proteomic information to genomic platforms - 'proteogenomics' - is providing unparalleled insight in cancer cell biology. Application of improved mass spectrometry technology and methodology, in particular the ability to analyse post-translational modifications (the PTMome), is providing a more complete picture of the dysregulated networks in cancer, and uncovering novel therapeutic targets. While the application of proteomics to discovery research will continue to rise, improved workflow standardisation and reproducibility is required before mass spectrometry can enter routine clinical use.

Comparable post-relapse outcomes between haploidentical and matched related donor allogeneic stem cell transplantation

We investigated the impact of donor type on post-relapse survival (PRS) in 85 patients with hematological relapse after their first allogeneic hematological stem cell transplantation (allo-HSCT) for hematological malignancy. The median follow-up was 64 months among survivors. Both 3-year overall survival and 3-year PRS were similar in haploidentical donor (HID) and matched sibling donor (MRD) transplantation (13.0%±4.7% vs 19.4%±7.1%, P=0.913 and 7.7±3.9% vs 9.7±5.3%, P= 0.667). Higher rates of post-relapse grade II-IV and III-IV acute GvHD (aGvHD) were observed in HID transplantation patients. A higher cumulative incidence of post-relapse extensive chronic GvHD was also observed for HID transplantation patients. Multivariate analyses confirmed that treatment including donor lymphocyte infusion (DLI), late relapse >1 year, and in first CR at transplantation were associated with superior PRS (P=0.012, hazard ratio (HR)=0.527 (0.320-0.866)); P=0.033, HR=0.534 (0.300-0.952) and P=0.046, HR=0.630 (0.400-0.992). The data suggest that post-relapse outcomes are comparable in HID and MRD transplantation, and that DLI is safe for relapsed patients after haploidentical transplantation.

Matched and mismatched unrelated donor compared to autologous stem cell transplantation for acute myeloid leukemia in first complete remission: a retrospective, propensity score-weighted analysis from the ALWP of the EBMT

BACKGROUND

Optimal post-remission strategy for patients with acute myeloid leukemia (AML) is matter of intense debate. Recent reports have shown stronger anti-leukemic activity but similar survival for allogeneic stem cell transplantation (allo-HSCT) from matched sibling donor compared to autologous transplantation (auto-HSCT); however, there is scarcity of literature confronting auto-HSCT with allo-HSCT from unrelated donor (UD-HSCT), especially mismatched UD-HSCT.

METHODS

We retrospectively compared outcome of allogeneic transplantation from matched (10/10 UD-HSCT) or mismatched at a single HLA-locus unrelated donor (9/10 UD-HSCT) to autologous transplantation in patients with AML in first complete remission (CR1). A total of 2879 patients were included; 1202 patients received auto-HSCT, 1302 10/10 UD-HSCT, and 375 9/10 UD-HSCT. A propensity score-weighted analysis was conducted to control for disease risk imbalances between the groups.

RESULTS

Matched 10/10 UD-HSCT was associated with the best leukemia-free survival (10/10 UD-HSCT vs auto-HSCT: HR 0.7, p = 0.0016). Leukemia-free survival was not statistically different between auto-HSCT and 9/10 UD-HSCT (9/10 UD-HSCT vs auto-HSCT: HR 0.8, p = 0.2). Overall survival was similar across the groups (10/10 UD-HSCT vs auto-HSCT: HR 0.98, p = 0.84; 9/10 UD-HSCT vs auto-HSCT: HR 1.1, p = 0.49). Notably, in intermediate-risk patients, OS was significantly worse for 9/10 UD-HSCT (9/10 UD-HSCT vs auto-HSCT: HR 1.6, p = 0.049), while it did not differ between auto-HSCT and 10/10 UD-HSCT (HR 0.95, p = 0.88). In favorable risk patients, auto-HSCT resulted in 3-year LFS and OS rates of 59 and 78 %, respectively.

CONCLUSIONS

Our findings suggest that in AML patients in CR1 lacking an HLA-matched sibling donor, 10/10 UD-HSCT significantly improves LFS, but this advantage does not translate in better OS compared to auto-HSCT. In intermediate-risk patients lacking a fully HLA-matched donor, auto-HSCT should be considered as a valid option, as better survival appears to be provided by auto-HSCT compared to mismatched UD-HSCT. Finally, auto-HSCT provided an encouraging outcome in patients with favorable risk AML.

FLT3 Inhibitors for Treating Acute Myeloid Leukemia

FLT3 (Fms-like tyrosine kinase 3) inhibitors are tyrosine kinase inhibitors. The first-generation FLT3 inhibitors were developed several years ago and include midostaurin, lestaurtinib, sunitinib, and sorafenib. They are relatively nonspecific for FLT3, with other potential targets that include platelet-derived growth factor receptor, vascular endothelial growth factor receptor, KIT, and Janus kinase 2. The second-generation inhibitors, including quizartinib, crenolanib, PLX3397, and ASP2215, are more potent and selective than the first-generation inhibitors. The greater potency and selectivity promises greater efficacy in FLT3-mutated acute myelogenous leukemia (AML) (particularly in patients with a greater allele burden) and less toxicity. A number of receptor tyrosine kinase inhibitors are being studied across virtually all disease settings, including frontline, relapsed and refractory, and maintenance, mainly in patients with FLT3-mutated AML. The future of FLT3 inhibitors in the treatment of AML, in combination with chemotherapy or stem cell transplant, appears bright. The present report reviews the current data on FLT3 inhibitors.

Aberrant activation of the PI3K/mTOR pathway promotes resistance to sorafenib in AML

Therapy directed against oncogenic FLT3 has been shown to induce response in patients with acute myeloid leukemia (AML), but these responses are almost always transient. To address the mechanism of FLT3 inhibitor resistance, we generated two resistant AML cell lines by sustained treatment with the FLT3 inhibitor sorafenib. Parental cell lines carry the FLT3-ITD (tandem duplication) mutation and are highly responsive to FLT3 inhibitors, whereas resistant cell lines display resistance to multiple FLT3 inhibitors. Sanger sequencing and protein mass-spectrometry did not identify any acquired mutations in FLT3 in the resistant cells. Moreover, sorafenib treatment effectively blocked FLT3 activation in resistant cells, whereas it was unable to block colony formation or cell survival, suggesting that the resistant cells are no longer FLT3 dependent. Gene expression analysis of sensitive and resistant cell lines, as well as of blasts from patients with sorafenib-resistant AML, suggested an enrichment of the PI3K/mTOR pathway in the resistant phenotype, which was further supported by next-generation sequencing and phospho-specific-antibody array analysis. Furthermore, a selective PI3K/mTOR inhibitor, gedatolisib, efficiently blocked proliferation, colony and tumor formation, and induced apoptosis in resistant cell lines. Gedatolisib significantly extended survival of mice in a sorafenib-resistant AML patient-derived xenograft model. Taken together, our data suggest that aberrant activation of the PI3K/mTOR pathway in FLT3-ITD-dependent AML results in resistance to drugs targeting FLT3.

The artful management of older patients with acute myeloid leukemia

Acute myeloid leukemia in older patients has historically had a dismal 10-15% long-term survival rate. Although patient frailty plays a role in this disappointing outcome, the primary driver of poor results remains the resistance of disease to current therapies. The optimal management of this difficult-to-treat disease should include a careful consideration of disease, patient and treatment factors. Disease factors include cytogenetic and molecular features and the history of an antecedent hematological disorder. Patient factors include age, performance status, comorbid conditions and individual patient preference. We favor intensive induction in most fit older patients but alternatives such as hypomethylating agents and low-dose cytarabine may be considered in patients with other comorbidities. Enrollment of patients into well designed clinical trials addressing important questions remains of utmost importance in order to advance the understanding and treatment of this disease although the best means of drug development remains a challenging dilemma.