BCL2 Inhibition: A New Paradigm for the Treatment of AML and Beyond

Olutasidenib in post-venetoclax patients with mutant isocitrate dehydrogenase 1 (mIDH1) acute myeloid leukemia (AML)

Olutasidenib, a potent, selective, oral, mutant isocitrate dehydrogenase 1 (mIDH1) inhibitor, is FDA-approved for relapsed/refractory (R/R) acute myeloid leukemia (AML). Here we report efficacy and safety of olutasidenib in 18 patients with mIDH1 AML who were relapsed (10), refractory (6) or had complete remission with incomplete hematologic recovery (CRi; 2) to a venetoclax combination. Of the 16 patients who were R/R, 4 (25%) achieved complete remission (CR), one (6.3%) achieved CR with partial hematologic recovery (CRh), and 7 (43.8%) achieved a composite complete remission (CRc). Median time to CRc was 1.9 months (range 1-2.8). As of data cutoff (18 June 2021), median duration of CRc was not reached (range, 1.2-NR, ongoing at 30.4+ months). Both patients with CRi at study entry achieved a CR. Safety was consistent with the overall profile of olutasidenib. Olutasidenib offers a valuable treatment option for patients with mIDH1 AML previously treated with venetoclax.

BCL-2 inhibition in haematological malignancies: Clinical application and complications

B-cell lymphoma-2 (BCL-2) family proteins are fundamental regulators of the intrinsic apoptotic pathway which modulate cellular fate. In many haematological malignancies, overexpression of anti-apoptotic factors (BCL-2, BCL-XL and MCL-1) circumvent apoptosis. To address this cancer hallmark, a concerted effort has been made to induce apoptosis by inhibiting BCL-2 family proteins. A series of highly selective BCL-2 homology 3 (BH3) domain mimetics are in clinical use and in ongoing clinical trials for acute myeloid leukaemia (AML), chronic myeloid leukaemia (CML), chronic lymphocytic leukaemia (CLL), and multiple myeloma (MM). These inhibitors serve as promising candidates, both as single agents or in combination therapy to improve patient outcomes. In other diseases such as follicular lymphoma, efficacy has been notably limited. There are also clinical problems with BCL-2 family inhibition, including drug resistance, disease relapse, tumour lysis syndrome, and clinically relevant cytopenias. Here, we provide a balanced view on both the clinical benefits of BCL-2 inhibition as well as the associated challenges.

Phosphoproteomic Characterization and Kinase Signature Predict Response to Venetoclax Plus 3+7 Chemotherapy in Acute Myeloid Leukemia

Resistance to chemotherapy remains a formidable obstacle in acute myeloid leukemia (AML) therapeutic management, necessitating the exploration of optimal strategies to maximize therapeutic benefits. Venetoclax with 3+7 daunorubicin and cytarabine (DAV regimen) in young adult de novo AML patients is evaluated. 90% of treated patients achieved complete remission, underscoring the potential of this regimen as a compelling therapeutic intervention. To elucidate underlying mechanisms governing response to DAV in AML, quantitative phosphoproteomics to discern distinct molecular signatures characterizing a subset of DAV-sensitive patients is used. Cluster analysis reveals an enrichment of phosphoproteins implicated in chromatin organization and RNA processing within DAV-susceptible and DA-resistant AML patients. Furthermore, kinase activity profiling identifies AURKB as a candidate indicator of DAV regimen efficacy in DA-resistant AML due to AURKB activation. Intriguingly, AML cells overexpressing AURKB exhibit attenuated MCL-1 expression, rendering them receptive to DAV treatment and maintaining them resistant to DA treatment. Moreover, the dataset delineates a shared kinase, AKT1, associated with DAV response. Notably, AKT1 inhibition augments the antileukemic efficacy of DAV treatment in AML. Overall, this phosphoproteomic study identifies the role of AURKB as a predictive biomarker for DA, but not DAV, resistance and proposes a promising strategy to counteract therapy resistance in AML.

Combating Acute Myeloid Leukemia via Sphingosine Kinase 1 Inhibitor-Nanomedicine Combination Therapy with Cytarabine or Venetoclax

MP-A08 is a novel sphingosine kinase 1 (SPHK1) inhibitor with activity against acute myeloid leukemia (AML). A rationally designed liposome-based encapsulation and delivery system has been shown to overcome the physicochemical challenges of MP-A08 and enable its effective delivery for improved efficacy and survival of mice engrafted with human AML in preclinical models. To establish therapies that overcome AML's heterogeneous nature, here we explored the combination of MP-A08-loaded liposomes with both the standard chemotherapy, cytarabine, and the targeted therapy, venetoclax, against human AML cell lines. Cytarabine (over the dose range of 0.1-0.5 µM) in combination with MP-A08 liposomes showed significant synergistic effects (as confirmed by the Chou-Talalay Combination Index) against the chemosensitised human AML cell lines MV4-11 and OCI-AML3. Venetoclax (over the dose range of 0.5-250 nM) in combination with MP-A08 liposomes showed significant synergistic effects against the chemosensitised human AML cell lines, particularly in venetoclax-resistant human AML cells. This strong synergistic effect is due to multiple mechanisms of action, i.e., inhibiting MCL-1 through SPHK1 inhibition, leading to ceramide accumulation, activation of protein kinase R, ATF4 upregulation, and NOXA activation, ultimately resulting in MCL-1 degradation. These combination therapies warrant further consideration and investigation in the search for a more comprehensive treatment strategy for AML.

Pharmacological Inhibition of PIP4K2 Potentiates Venetoclax-Induced Apoptosis in Acute Myeloid Leukemia

Phosphatidylinositol-5-phosphate 4-kinase type 2 (PIP4K2) protein family members (PIP4K2A, PIP4K2B, and PIP4K2C) participate in the generation of PIP4,5P2, which acts as a secondary messenger in signal transduction, a substrate for metabolic processes, and has structural functions. In patients with acute myeloid leukemia (AML), high PIP4K2A and PIP4K2C levels are independent markers of a worse prognosis. Recently, our research group reported that THZ-P1-2 (PIP4K2 pan-inhibitor) exhibits anti-leukemic activity by disrupting mitochondrial homeostasis and autophagy in AML models. In the present study, we characterized the expression of PIP4K2 in the myeloid compartment of hematopoietic cells, as well as in AML cell lines and clinical samples with different genetic abnormalities. In ex vivo assays, PIP4K2 expression levels were related to sensitivity and resistance to several antileukemia drugs and highlighted the association between high PIP4K2A levels and resistance to venetoclax. The combination of THZ-P1-2 and venetoclax showed potentiating effects in reducing viability and inducing apoptosis in AML cells. A combined treatment differentially modulated multiple genes, including TAp73, BCL2, MCL1, and BCL2A1. In summary, our study identified the correlation between the expression of PIP4K2 and the response to antineoplastic agents in ex vivo assays in AML and exposed vulnerabilities that may be exploited in combined therapies, which could result in better therapeutic responses.

Venetoclax with Hypomethylating Agents in Newly Diagnosed Acute Myeloid Leukemia: A Systematic Review and Meta-Analysis of Survival Data from Real-World Studies

In recent years, the association of venetoclax (VEN) with hypomethylating agents (HMAs) significantly improved the outcome of patients with newly diagnosed acute myeloid leukemia (AML) who were unfit for intensive chemotherapy and became the standard of care after the publication of the pivotal RCT VIALE-A. However, it is still not clear to what extent the results observed in the VIALE-A apply to a real-world setting. For this reason, we carried out a systematic review and meta-analysis of real-world studies on newly diagnosed patients with AML, ineligible for intensive induction chemotherapy, receiving first-line VEN+HMA. We then compared their results in term of survival with those from the VIALE-A. Kaplan-Meier curves were extracted from all included studies and individual survival data was reconstructed. We then estimated a pooled survival curve and compared it with the results of the VIALE-A using the log-rank test. We also conducted a secondary analysis including only studies considering VEN plus azacytidine (AZA) as treatment, as this was the schedule originally used in the VIALE-A. Nineteen real-world studies met the inclusion criteria and were included in the systematic review. Most of them reported a worse survival than the VIALE-A. The pooled survival curve was similar to that reported in the VIALE-A during the first three months of treatment but diverged thereafter (p-value = 0.0001). The pooled median survival among the real-world studies was 9.37 months (95%CI 8.81-10.5), substantially lower than that reported in the VIALE-A (14.7 months; 95%CI 11.9-18.7). Results slightly increased when the analysis was restricted to the studies using VEN+AZA as treatment (median survival: 11.5 months; 95%CI 10.2-14.8). Survival of newly diagnosed AML patients treated with VEN+HMAs in a real-world setting seems to be lower than previously reported in the VIALE-A, while the effect of VEN+AZA is more in line with expected results. Future studies are needed to evaluate whether this apparent discrepancy is due to the different characteristics of enrolled patients or to a non-optimal adherence to therapy, and whether alternative regimens can provide better results in terms of safety and effectiveness.