A Phase II Study of Azacitidine, Venetoclax and Trametinib in Relapsed or Refractory AML Harboring RAS Pathway-Activating Mutations

Case report: Venetoclax plus Azacitidine in treatment of acute undifferentiated leukemia

OBJECTIVES

Acute undifferentiated leukemia (AUL) is a clinical rare leukemia with an overall poor prognosis. Currently, there are no well-established treatment guidelines for AUL, further exploration of optimal treatment options is now required.

METHODS

We report an AUL patient who was complicated by a NRAS mutation and del5q was admitted to our hospital and we present the clinical features. In addition, we conducted a literature review.

RESULTS

The "VA" scheme combines agents Venetoclax and Azacitidine that have synergistic therapeutic effect with a tolerable safety profile. There is no previous report of the "VA" scheme employed in AUL treatment. An AUL patient who was complicated by a NRAS mutation and del5q was admitted to our hospital. The "VA" scheme was administrated, and complete remission (CR) was achieved at the end of the first cycle. The patient then underwent HLA-identical sibling allogeneic hematopoietic stem cell transplantation.

DISCUSSION

The "VA" scheme has been extensively used in AML treatment, but its application in AUL treatment has not yet been reported. This study is the first to report an AUL patient treated with the "VA" scheme and achieved CR. Our result preliminarily suggested the effectiveness and safety of the "VA" scheme in AUL treatment, but validation is required in more clinical samples. The "VA" scheme provides a new treatment option for AUL patients and deserves further clinical promotion.

Venetoclax with low-dose cytarabine, a forgotten combination in patients with acute myeloid leukemia ineligible for intensive chemotherapy: a systematic review

BACKGROUND

Based on the VIALE-A and VIALE-C studies, the Food and Drug Administration approved venetoclax in 2020 in combination with azacitidine or low-dose cytarabine for the treatment of patients with acute myeloid leukemia ineligible for intensive chemotherapy. After the publication of these studies, venetoclax/azacitidine was assumed to be superior to venetoclax/low-dose cytarabine; however, these studies were not designed to demonstrate superiority between these combinations. Therefore, we conducted a systematic review to describe overall survival, complete remission rate, and composite complete remission rate to assess response of these two regimens in patients with newly diagnosed acute myeloid leukemia who are ineligible for intensive chemotherapy.

MATERIALS AND METHODS

The PubMed and Web of Science databases were searched for retrospective studies and complete remission, composite complete remission, and overall survival rates were recorded.

RESULTS

Only 11 of the 815 publications identified were eligible to be included n this review, ten studies evaluated the venetoclax/azacitidine combination and one study evaluated the venetoclax/low-dose cytarabine combination. The median overall survival for venetoclax/azacitidine was 10.75 months, whereas for venetoclax/low-dose cytarabine the median overall survival had not been reached at the time of publication. Composite complete remission was 63.3 % for venetoclax/azacitidine and 90 % for venetoclax/low-dose cytarabine. Adverse events were similar for both combinations.

CONCLUSIONS

A limited number of studies investigating the venetoclax/low-dose cytarabine combination exist. Based on the available data, the superiority of venetoclax/azacitidine over venetoclax/low-dose cytarabine cannot be assumed for all acute myeloid leukemia patients who are ineligible for intensive chemotherapy. Venetoclax/low-dose cytarabine can still be considered as an option for the drug combinations currently under investigation.

Adhesion GPCR ADGRE2 Maintains Proteostasis to Promote Progression in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is an aggressive and heterogeneous hematologic malignancy. In elderly patients, AML incidence is high and has a poor prognosis due to a lack of effective therapies. G protein-coupled receptors (GPCR) play integral roles in physiologic processes and human diseases. Particularly, one third of adhesion GPCRs, the second largest group of GPCRs, are highly expressed in hematopoietic stem and progenitor cells or lineage cells. Here, we investigate the role of adhesion GPCRs in AML and whether they could be harnessed as antileukemia targets. Systematic screening of the impact of adhesion GPCRs on AML functionality by bioinformatic and functional analyses revealed high expression of ADGRE2 in AML, particularly in leukemic stem cells, which is associated with poor patient outcomes. Silencing ADGRE2 not only exerts antileukemic effects in AML cell lines and cells derived from patients with AML in vitro, but also delays AML progression in xenograft models in vivo. Mechanistically, ADGRE2 activates phospholipase Cβ/protein kinase C/MEK/ERK signaling to enhance the expression of AP1 and transcriptionally drive the expression of DUSP1, a protein phosphatase. DUSP1 dephosphorylates Ser16 in the J-domain of the co-chaperone DNAJB1, which facilitates the DNAJB1-HSP70 interaction and maintenance of proteostasis in AML. Finally, combined inhibition of MEK, AP1, and DUSP1 exhibits robust therapeutic efficacy in AML xenograft mouse models. Collectively, this study deciphers the roles and mechanisms of ADGRE2 in AML and provides a promising therapeutic strategy for treating AML. Significance: Increased expression of the adhesion GPCR member ADGRE2 in AML supports leukemia stem cell self-renewal and leukemogenesis by modulating proteostasis via an MEK/AP1/DUSP1 axis, which can be targeted to suppress AML progression.

Venetoclax and Cobimetinib in Relapsed/Refractory AML: A Phase 1b Trial

BACKGROUND

Therapies for relapsed/refractory acute myeloid leukemia remain limited and outcomes poor, especially amongst patients who are ineligible for cytotoxic chemotherapy or targeted therapies.

PATIENTS AND METHODS

This phase 1b trial evaluated venetoclax, a B-cell lymphoma-2 (BCL-2) inhibitor, plus cobimetinib, a MEK1/2 inhibitor, in patients with relapsed/refractory acute myeloid leukemia, ineligible for cytotoxic chemotherapy. Two-dimensional dose-escalation was performed for venetoclax dosed daily, and for cobimetinib dosed on days 1-21 of each 28-day cycle.

RESULTS

Thirty patients (median [range] age: 71.5 years [60-84]) received venetoclax-cobimetinib. The most common adverse events (AEs; in ≥40.0% of patients) were diarrhea (80.0%), nausea (60.0%), vomiting (40.0%), febrile neutropenia (40.0%), and fatigue (40.0%). Overall, 66.7% and 23.3% of patients experienced AEs leading to dose modification/interruption or treatment withdrawal, respectively. The composite complete remission (CRc) rate (complete remission [CR] + CR with incomplete blood count recovery + CR with incomplete platelet recovery) was 15.6%; antileukemic response rate (CRc + morphologic leukemia-free state/partial remission) was 18.8%. For the recommended phase 2 dose (venetoclax: 600 mg; cobimetinib: 40 mg), CRc and antileukemic response rates were both 12.5%. Failure to achieve an antileukemic response was associated with elevated baseline phosphorylated ERK and MCL-1 levels, but not BCL-xL. Baseline mutations in ≥1 signaling gene or TP53 were noted in nonresponders and emerged on treatment. Pharmacodynamic biomarkers revealed inconsistent, transient inhibition of the mitogen-activated protein kinase (MAPK) pathway.

CONCLUSION

Venetoclax-cobimetinib showed limited preliminary efficacy similar to single-agent venetoclax, but with added toxicity. Our findings will inform future trials of BCL-2/MAPK pathway inhibitor combinations.

Targeting CCL2/CCR2 Signaling Overcomes MEK Inhibitor Resistance in Acute Myeloid Leukemia

PURPOSE

Emerging evidence underscores the critical role of extrinsic factors within the microenvironment in protecting leukemia cells from therapeutic interventions, driving disease progression, and promoting drug resistance in acute myeloid leukemia (AML). This finding emphasizes the need for the identification of targeted therapies that inhibit intrinsic and extrinsic signaling to overcome drug resistance in AML.

EXPERIMENTAL DESIGN

We performed a comprehensive analysis utilizing a cohort of ∼300 AML patient samples. This analysis encompassed the evaluation of secreted cytokines/growth factors, gene expression, and ex vivo drug sensitivity to small molecules. Our investigation pinpointed a notable association between elevated levels of CCL2 and diminished sensitivity to the MEK inhibitors (MEKi). We validated this association through loss-of-function and pharmacologic inhibition studies. Further, we deployed global phosphoproteomics and CRISPR/Cas9 screening to identify the mechanism of CCR2-mediated MEKi resistance in AML.

RESULTS

Our multifaceted analysis unveiled that CCL2 activates multiple prosurvival pathways, including MAPK and cell-cycle regulation in MEKi-resistant cells. Employing combination strategies to simultaneously target these pathways heightened growth inhibition in AML cells. Both genetic and pharmacologic inhibition of CCR2 sensitized AML cells to trametinib, suppressing proliferation while enhancing apoptosis. These findings underscore a new role for CCL2 in MEKi resistance, offering combination therapies as an avenue to circumvent this resistance.

CONCLUSIONS

Our study demonstrates a compelling rationale for translating CCL2/CCR2 axis inhibitors in combination with MEK pathway-targeting therapies, as a potent strategy for combating drug resistance in AML. This approach has the potential to enhance the efficacy of treatments to improve AML patient outcomes.

AML treatment: conventional chemotherapy and emerging novel agents

Acute myeloid leukemia (AML) is driven by complex mutations and cytogenetic abnormalities with profound tumoral heterogeneity, making it challenging to treat. Ten years ago, the 5-year survival rate of patients with AML was only 29% with conventional chemotherapy and stem cell transplantation. All attempts to improve conventional therapy over the previous 40 years had failed. Now, new genomic, immunological, and molecular insights have led to a renaissance in AML therapy. Improvements to standard chemotherapy and a wave of new targeted therapies have been developed. However, how best to incorporate these advances into frontline therapy and sequence them in relapse is not firmly established. In this review, we highlight current treatments of AML, targeted agents, and pioneering attempts to synthesize these developments into a rational standard of care (SoC).

Venetoclax resistance in acute myeloid leukaemia-Clinical and biological insights

Venetoclax, an oral BCL-2 inhibitor, has been widely incorporated in the treatment of acute myeloid leukaemia. The combination of hypomethylating agents and venetoclax is the current standard of care for elderly and patient's ineligible for aggressive therapies. However, venetoclax is being increasingly used with aggressive chemotherapy regimens both in the front line and in the relapse setting. Our growing experience and intensive research demonstrate that certain genetic abnormalities are associated with venetoclax sensitivity, while others with resistance, and that resistance can emerge during treatment leading to disease relapse. In the current review, we provide a summary of the known mechanisms of venetoclax cytotoxicity, both regarding the inhibition of BCL-2-mediated apoptosis and its effect on cell metabolism. We describe how these pathways are linked to venetoclax resistance and are associated with specific mutations. Finally, we provide the rationale for novel drug combinations in current and future clinical trials.

High throughput screening aids clinical decision-making in refractory acute myeloid leukaemia

BACKGROUND

Despite advances in therapeutics for adverse-risk acute myeloid leukaemia (AML), overall survival remains poor, especially in refractory disease. Comprehensive tumour profiling and pre-clinical drug testing can identify effective personalised therapies.

CASE

We describe a case of ETV6-MECOM fusion-positive refractory AML, where molecular analysis and in vitro high throughput drug screening identified a tolerable, novel targeted therapy and provided rationale for avoiding what could have been a toxic treatment regimen. Ruxolitinib combined with hydroxyurea led to disease control and enhanced quality-of-life in a patient unsuitable for intensified chemotherapy or allogeneic stem cell transplantation.

CONCLUSION

This case report demonstrates the feasibility and role of combination pre-clinical high throughput screening to aid decision making in high-risk leukaemia. It also demonstrates the role a JAK1/2 inhibitor can have in the palliative setting in select patients with AML.

Innovations in conditioning and post-transplant maintenance in AML: genomically informed revelations on the graft-versus-leukemia effect

Acute Myeloid Leukemia (AML) is the prototype of cancer genomics as it was the first published cancer genome. Large-scale next generation/massively parallel sequencing efforts have identified recurrent alterations that inform prognosis and have guided the development of targeted therapies. Despite changes in the frontline and relapsed standard of care stemming from the success of small molecules targeting FLT3, IDH1/2, and apoptotic pathways, allogeneic stem cell transplantation (alloHSCT) and the resulting graft-versus-leukemia (GVL) effect remains the only curative path for most patients. Advances in conditioning regimens, graft-vs-host disease prophylaxis, anti-infective agents, and supportive care have made this modality feasible, reducing transplant related mortality even among patients with advanced age or medical comorbidities. As such, relapse has emerged now as the most common cause of transplant failure. Relapse may occur after alloHSCT because residual disease clones persist after transplant, and develop immune escape from GVL, or such clones may proliferate rapidly early after alloHSCT, and outpace donor immune reconstitution, leading to relapse before any GVL effect could set in. To address this issue, genomically informed therapies are increasingly being incorporated into pre-transplant conditioning, or as post-transplant maintenance or pre-emptive therapy in the setting of mixed/falling donor chimerism or persistent detectable measurable residual disease (MRD). There is an urgent need to better understand how these emerging therapies modulate the two sides of the GVHD vs. GVL coin: 1) how molecularly or immunologically targeted therapies affect engraftment, GVHD potential, and function of the donor graft and 2) how these therapies affect the immunogenicity and sensitivity of leukemic clones to the GVL effect. By maximizing the synergistic action of molecularly targeted agents, immunomodulating agents, conventional chemotherapy, and the GVL effect, there is hope for improving outcomes for patients with this often-devastating disease.

Therapeutic application of human type 2 innate lymphoid cells via induction of granzyme B-mediated tumor cell death

The therapeutic potential for human type 2 innate lymphoid cells (ILC2s) has been underexplored. Although not observed in mouse ILC2s, we found that human ILC2s secrete granzyme B (GZMB) and directly lyse tumor cells by inducing pyroptosis and/or apoptosis, which is governed by a DNAM-1-CD112/CD155 interaction that inactivates the negative regulator FOXO1. Over time, the high surface density expression of CD155 in acute myeloid leukemia cells impairs the expression of DNAM-1 and GZMB, thus allowing for immune evasion. We describe a reliable platform capable of up to 2,000-fold expansion of human ILC2s within 4 weeks, whose molecular and cellular ILC2 profiles were validated by single-cell RNA sequencing. In both leukemia and solid tumor models, exogenously administered expanded human ILC2s show significant antitumor effects in vivo. Collectively, we demonstrate previously unreported properties of human ILC2s and identify this innate immune cell subset as a member of the cytolytic immune effector cell family.

Allosteric SHP2 inhibition increases apoptotic dependency on BCL2 and synergizes with venetoclax in FLT3- and KIT-mutant AML

Mutations in the receptor tyrosine kinases (RTKs) FLT3 and KIT are frequent and associated with poor outcomes in acute myeloid leukemia (AML). Although selective FLT3 inhibitors (FLT3i) are clinically effective, remissions are short-lived due to secondary resistance characterized by acquired mutations constitutively activating the RAS/MAPK pathway. Hereby, we report the pre-clinical efficacy of co-targeting SHP2, a critical node in MAPK signaling, and BCL2 in RTK-driven AML. The allosteric SHP2 inhibitor RMC-4550 suppresses proliferation of AML cell lines with FLT3 and KIT mutations, including cell lines with acquired resistance to FLT3i. We demonstrate that pharmacologic SHP2 inhibition unveils an Achilles' heel of RTK-driven AML, increasing apoptotic dependency on BCL2 via MAPK-dependent mechanisms, including upregulation of BMF and downregulation of MCL1. Consequently, RMC-4550 and venetoclax are synergistically lethal in AML cell lines and in clinically relevant xenograft models. Our results provide mechanistic rationale and pre-clinical evidence for co-targeting SHP2 and BCL2 in RTK-driven AML.

Recent advances in precision medicine for acute myeloid leukemia

PURPOSE OF REVIEW

Acute myeloid leukemia (AML) is a heterogeneous disease, in which treatment response and patient survival are highly conditioned by the leukemia biology. The aim of this review is to summarize recent advances in AML classification, risk stratification models, measurable residual disease (MRD) and the increasing number of treatment options that are paving the way towards precision medicine in AML.

RECENT FINDINGS

AML classification and risk stratification were recently updated by incorporating novel molecular markers that are important for diagnosis and outcome prediction. In addition, the impact of co-mutational patterns is under investigation and novel approaches using machine learning algorithms are starting to be used for individualized risk estimation. Molecular markers are also becoming useful in predicting response to non-intensive treatments. MRD informs of treatment response with high sensitivity, allowing dynamic patient risk assessment and early intervention. Finally, important advances were made in AML therapy, with an increasing number of targeted therapies becoming available and many novel treatment approaches being under development with promising early results.

SUMMARY

A better understanding of AML biology is leading to improved risk stratification and important advances in treatments, which are allowing the development of precision medicine in AML at an unprecedented pace.

Targeting apoptosis dysregulation in myeloid malignancies - The promise of a therapeutic revolution

In recent years, the therapeutic landscape of myeloid malignancies has been completely revolutionized by the introduction of several new drugs, targeting molecular alterations or pathways crucial for leukemia cells survival. Particularly, many agents targeting apoptosis have been investigated in both pre-clinical and clinical studies. For instance, venetoclax, a pro-apoptotic agent active on BCL-2 signaling, has been successfully used in the treatment of acute myeloid leukemia (AML). The impressive results achieved in this context have made the apoptotic pathway an attractive target also in other myeloid neoplasms, translating the experience of AML. Therefore, several drugs are now under investigation either as single or in combination strategies, due to their synergistic efficacy and capacity to overcome resistance. In this paper, we will review the mechanisms of apoptosis and the specific drugs currently used and under investigation for the treatment of myeloid neoplasia, identifying critical research necessities for the upcoming years.

Acute myeloid leukemia: from NGS, through scRNA-seq, to CAR-T. dissect cancer heterogeneity and tailor the treatment

Acute myeloid leukemia (AML) is a malignant blood cancer with marked cellular heterogeneity due to altered maturation and differentiation of myeloid blasts, the possible causes of which are transcriptional or epigenetic alterations, impaired apoptosis, and excessive cell proliferation. This neoplasm has a high rate of resistance to anticancer therapies and thus a high risk of relapse and mortality because of both the biological diversity of the patient and intratumoral heterogeneity due to the acquisition of new somatic changes. For more than 40 years, the old gold standard "one size fits all" treatment approach included intensive chemotherapy treatment with anthracyclines and cytarabine.The manuscript first traces the evolution of the understanding of the pathology from the 1970s to the present. The enormous strides made in its categorization prove to be crucial for risk stratification, enabling an increasingly personalized diagnosis and treatment approach.Subsequently, we highlight how, over the past 15 years, technological advances enabling single cell RNA sequencing and T-cell modification based on the genomic tools are affecting the classification and treatment of AML. At the dawn of the new millennium, the advent of high-throughput next-generation sequencing technologies has enabled the profiling of patients evidencing different facets of the same disease, stratifying risk, and identifying new possible therapeutic targets that have subsequently been validated. Currently, the possibility of investigating tumor heterogeneity at the single cell level, profiling the tumor at the time of diagnosis or after treatments exist. This would allow the identification of underrepresented cellular subclones or clones resistant to therapeutic approaches and thus responsible for post-treatment relapse that would otherwise be difficult to detect with bulk investigations on the tumor biopsy. Single-cell investigation will then allow even greater personalization of therapy to the genetic and transcriptional profile of the tumor, saving valuable time and dangerous side effects. The era of personalized medicine will take a huge step forward through the disclosure of each individual piece of the complex puzzle that is cancer pathology, to implement a "tailored" therapeutic approach based also on engineered CAR-T cells.

Pro-Apoptotic Activity of MCL-1 Inhibitor in Trametinib-Resistant Melanoma Cells Depends on Their Phenotypes and Is Modulated by Reversible Alterations Induced by Trametinib Withdrawal

BACKGROUND

Although BRAFV600/MEK inhibitors improved the treatment of melanoma patients, resistance is acquired almost inevitably.

METHODS

Trametinib withdrawal/rechallenge and MCL-1 inhibition in trametinib-resistance models displaying distinct p-ERK1/2 levels were investigated.

RESULTS

Trametinib withdrawal/rechallenge caused reversible changes in ERK1/2 activity impacting the balance between pro-survival and pro-apoptotic proteins. Reversible alterations were found in MCL-1 levels and MCL-1 inhibitors, BIM and NOXA. Taking advantage of melanoma cell dependency on MCL-1 for survival, we used S63845. While it was designed to inhibit MCL-1 activity, we showed that it also significantly reduced NOXA levels. S63845-induced apoptosis was detected as the enhancement of Annexin V-positivity, caspase-3/7 activation and histone H2AX phosphorylation. Percentages of Annexin V-positive cells were increased most efficiently in trametinib-resistant melanoma cells displaying the p-ERK1/2low/MCL-1low/BIMhigh/NOXAlow phenotype with EC50 values at concentrations as low as 0.1 μM. Higher ERK1/2 activity associated with increased MCL-1 level and reduced BIM level limited pro-apoptotic activity of S63845 further influenced by a NOXA level.

CONCLUSIONS

Our study supports the notion that the efficiency of an agent designed to target a single protein can largely depend on the phenotype of cancer cells. Thus, it is important to define appropriate phenotype determinants to stratify the patients for the novel therapy.

Transcriptional Response to Standard AML Drugs Identifies Synergistic Combinations

Unlike genomic alterations, gene expression profiles have not been widely used to refine cancer therapies. We analyzed transcriptional changes in acute myeloid leukemia (AML) cell lines in response to standard first-line AML drugs cytarabine and daunorubicin by means of RNA sequencing. Those changes were highly cell- and treatment-specific. By comparing the changes unique to treatment-sensitive and treatment-resistant AML cells, we enriched for treatment-relevant genes. Those genes were associated with drug response-specific pathways, including calcium ion-dependent exocytosis and chromatin remodeling. Pharmacological mimicking of those changes using EGFR and MEK inhibitors enhanced the response to daunorubicin with minimum standalone cytotoxicity. The synergistic response was observed even in the cell lines beyond those used for the discovery, including a primary AML sample. Additionally, publicly available cytotoxicity data confirmed the synergistic effect of EGFR inhibitors in combination with daunorubicin in all 60 investigated cancer cell lines. In conclusion, we demonstrate the utility of treatment-evoked gene expression changes to formulate rational drug combinations. This approach could improve the standard AML therapy, especially in older patients.