ABT-199, a potent and selective BCL-2 inhibitor, achieves antitumor activity while sparing platelets

Small molecules targeting the eubacterial β-sliding clamp discovered by combined in silico and in vitro screening approaches

Antibiotic resistance stands as the foremost post-pandemic threat to public health. The urgent need for new, effective antibacterial treatments is evident. Protein-protein interactions (PPIs), owing to their pivotal role in microbial physiology, emerge as novel and attractive targets. Particularly promising is the α-subunit/β-sliding clamp interaction, crucial for the replicative competence of bacterial DNA polymerase III holoenzyme. Through pharmacophore-based virtual screening, we identified 4,000 candidate small molecule inhibitors targeting the β-clamp binding pocket. Subsequently, these candidates underwent evaluation using the BRET assay in yeast cells. Following this, three hits and 28 analogues were validated via Protein Thermal Shift and competitive ELISA assays. Among them, thiazolo[4,5-d]-pyrimidinedione and benzanilide derivatives exhibited micromolar potency in displacing the β-clamp protein partner and inhibiting DNA replication. This screening campaign unveiled new chemical classes of α/β-clamp PPI disruptors capable of inhibiting DNA polymerase III activity, which lend themselves for further optimisation to improve their antibacterial efficacy.

Discovery of XZ338, a highly potent BCL-XL degrader

BCL-XL is a crucial anti-apoptotic protein involved in tumorigenesis and resistance to cancer chemotherapy. Transitioning from conventional inhibitors to PROTAC degraders has shown promising potential, particularly in minimizing the on-target thrombocytopenia linked to BCL-XL inhibition. However, reported BCL-XL degraders were mostly derived from BCL-XL/BCL-2 dual inhibitor ABT-263, which also inhibits or degrades BCL-2 and can potentially cause neutropenia when combined with conventional chemotherapy as seen with ABT-263 in the clinic. The goal of the present study is to develop a highly specific BCL-XL degrader without BCL-2 inhibition/degradation. In this study, XZ338, a highly potent and selective BCL-XL degrader derived from BCL-XL specific inhibitor A-1331852, was generated. XZ338 is 70-fold more potent than ABT-263 against MOLT-4 T-ALL cells, with over 89-fold selectivity for MOLT-4 cells over human platelets.

Pharmacological modulation of cellular senescence: Implications for breast cancer progression and therapeutic strategies

Senescence, defined by the cessation of cell proliferation, plays a critical and multifaceted role in breast cancer progression and treatment. Senescent cells produce senescence-associated secretory phenotypes (SASP) comprising inflammatory cytokines, chemokines, and small molecules, which actively shape the tumor microenvironment, influencing cancer development, progression, and metastasis. This review provides a comprehensive analysis of the types and origins of senescent cells in breast cancer, alongside their markers and detection methods. Special focus is placed on pharmacological strategies targeting senescence, including drugs that induce or inhibit senescence, their molecular mechanisms, and their roles in therapeutic outcomes when combined with chemotherapy and radiotherapy. By exploring these pharmacological interventions and their impact on breast cancer treatment, this review underscores the potential of senescence-targeting therapies to revolutionize breast cancer management.

Targeting anti-apoptotic mechanisms in tumour cells: Strategies for enhancing Cancer therapy

Anti-cancer drug's cytotoxicity is determined by their ability to induce predetermined cell demise, commonly called apoptosis. The cancer-causing cells are able to evade cell death, which has been affiliated with both malignancy as well as resistance to cancer treatments. In order to avoid cell death, cancerous tumour cells often produce an abundance of anti-apoptotic proteins, becoming "dependent" on them. Consequently, protein inhibitors of cell death may prove to be beneficial as pharmacological targets for the future creation of cancer therapies. This article examines the molecular routes of apoptosis, its clinical manifestations, anti-cancer therapy options that target the intrinsic mechanism of apoptosis, proteins that prevent cell death, and members of the B-lymphoma-2 subset. In addition, novel approaches to cell death are highlighted, including how curcumin mitigates chemotherapy-induced apoptosis in healthy tissues and the various ways melatonin modifies apoptosis to improve cancer treatment efficacy, particularly through the TNF superfamily. Cancer treatment-induced increases in anti-apoptotic proteins lead to drug resistance; yet, ligands that trigger cell death by inhibiting these proteins are expected to improve chemotherapy's efficacy. The potential of frequency-modulated dietary phytochemicals as a cancer therapeutic pathway, including autophagy and apoptosis, is also explored. This approach may be more efficient than inhibition alone in overcoming drug resistance. Consequently, this method has the potential to allow for lower medication concentrations, reducing cytotoxicity and unwanted side effects.

Recent update on the development of HPV16 inhibitors for cervical cancer

Persistent infection with human papillomavirus (HPV) can lead to cervical cancer (CC), which is the fourth most commonly diagnosed cancer in women globally. In this review, we have explained the HPV genome and the development of CC. Additionally, we summarized recently discovered small molecules that act as inhibitors of HPV-16. These molecules were identified through experimental and in-silico studies aimed at preventing or treating CC. HPV-16 and HPV-18 are the most common subtypes of HPV that cause CC globally. E6 oncoprotein of HPV-16 is considered the primary cause of CC progression. Therefore, E6 is the most focused targeted protein for developing specific and novel therapeutic inhibitors to treat HPV-related cancers. In recent years, various HPV inhibitors have been identified by means of experimental and in-silico studies. In addition, artificial intelligence-based medical diagnostic tools have grown more popular as they are capable of screening and diagnosing HPV-related cancer.

The pan-BH-3 mimetic, obatoclax, synergistically enhances cisplatin-induced apoptosis in oral squamous cell carcinoma through a mechanism that involves degradation of the pro-survival protein Mcl-1

OBJECTIVES

The purpose of the study was to elucidate the role of the Bcl-2 family of proteins in mediating cisplatin resistance in oral squamous cell carcinoma (OSCC). The value of the BH3-mimetics venetoclax and obatoclax as sensitisers for cisplatin treatment in OSCC was also evaluated.

DESIGN

In this study the expression levels of a series of pro- and anti-apoptotic members of the Bcl-2 family in paired cisplatin-sensitive (SCC4) and resistant (SCC4cisR) tongue squamous carcinoma cell lines were examined by western blotting. The apoptotic rate induced by cisplatin and BH3-mimetics venetoclax and obatoclax alone or in combination in OSCC was also evaluated by Annexin V/Propidium Iodide double-stained flow cytometric assays.

RESULTS

Obatoclax was shown to synergistically enhance cisplatin-induced apoptosis, and this enhancement was associated with a marked degradation in pro-survival Mcl-1 and upregulation in conformationally active form of pro-apoptotic Bak.

CONCLUSIONS

Our study presents novel insights into the relationship between the Bcl-2 family and cisplatin efficacy in OSCC. It also demonstrates that targeted therapy with BH-3 mimetics, such as obatoclax, may represent a new strategy for OSCC therapy.

Inextricable association of connective tissue disease with B‑cell lymphoma (Review)

Connective tissue disease (CTD) is a kind of autoimmune disease with multisystem damage that mainly involves the bone, muscle and the vascular system. Patients with CTD have an increased incidence of malignant tumors, particularly hematological malignancies, compared to the general population. This association of autoimmune diseases with lymphoproliferative diseases is bidirectional. There is a heightened risk of B-cell lymphoma development among patients with CTD, and patients with autoimmune disease display a higher prevalence of non-Hodgkin lymphoma compared to the general population. More than 80% of malignant tumours occur after or at the same time as CTD develops. Among secondary lymphomas, the most common aggressive type of lymphoma is diffuse large B-cell lymphoma, while the most common indolent type is marginal zone lymphoma. Novel targets in patients with B-cell lymphoma are BCL2, the NF-κB pathway, components of the BCR activator of RhoGEF and GTPase signalling pathway and the PI3K-mTOR pathway. In this review, information is provided on the common types of B-cell lymphoma in CTD, the pathogenic factors implicated in lymphoma development and recent advancements in therapies effective for both autoimmune conditions and malignant lymphoproliferative diseases.

Venetoclax Combined With Chemotherapy in Pediatric and Adolescent/Young Adult Patients With Relapsed/Refractory Acute Lymphoblastic Leukemia

BACKGROUND

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer, and although many patients respond to induction therapy, those who relapse or have refractory disease face a poor prognosis. Venetoclax has promising preclinical and clinical activity in ALL. Here, we report the safety and preliminary efficacy of venetoclax combined with chemotherapy in pediatric and adolescent/young adult patients with relapsed/refractory ALL.

PROCEDURE

This phase 1, open-label, two-part, multicenter study evaluated venetoclax combined with chemotherapy in pediatric and adolescent/young adult patients (<25 years of age) with relapsed/refractory ALL. The study is registered with ClinicalTrials.gov, NCT03236857.

RESULTS

Thirty-one patients were treated and received venetoclax monotherapy (n = 1), venetoclax plus dexamethasone and/or vincristine and/or pegasparaginase (VXL; n = 20) or venetoclax plus cytarabine and/or etoposide and/or pegasparaginase (n = 10). Patients were heavily pretreated, with a median of 3 prior lines of therapy. The most common grade 3/4 treatment-emergent adverse event was febrile neutropenia (55%). One fatal adverse event possibly related to venetoclax occurred. The overall response rate of treated patients was 42%, with all responding patients achieving complete remission/complete remission with incomplete marrow recovery. In biomarker-evaluable patients, responses to venetoclax plus VXL-based or cytarabine-based chemotherapy were observed in patients harboring a range of genetic alterations and heterogeneous BH3 family member dependencies.

CONCLUSIONS

Venetoclax plus VXL-based or cytarabine-based chemotherapy was overall well tolerated, with promising preliminary efficacy.

Effects of venetoclax, a BCL2 inhibitor, in systemic chronic active Epstein-Barr virus disease

Systemic chronic active Epstein-Barr virus disease (sCAEBV) is a chemotherapy-resistant, EBV-positive T- or NK-cell lymphoproliferative disorder characterized by persistent systemic inflammation driven by the activation of EBV-infected cells. In this study, we explored BCL2, an anti-apoptotic factor implicated in various hematopoietic malignancies, as a potential therapeutic target for sCAEBV, focusing on the effects of its inhibitor, venetoclax. We confirmed BCL2 expression in EBV-positive T- and NK-cell lines and peripheral blood mononuclear cells (PBMCs) from sCAEBV patients using western blotting. Immunofluorescence staining further revealed BCL2 expression in EBV-infected cells within patient-derived PBMCs. Venetoclax treatment reduced the viability of EBV-positive cell lines and patient-derived PBMCs in a dose-dependent manner and induced apoptosis in these cells. Moreover, venetoclax suppressed the mRNA expression of the inflammatory cytokine IFN-γ in patient-derived PBMCs. To evaluate the in vivo effects of venetoclax, we utilized sCAEBV xenograft model generated by transplanting patient-derived PBMCs into NOD/Shi-scid/IL-2Rγnull mice. No engraftment of EBV-infected cells was observed in mice treated with venetoclax, whereas one out of three mice in the untreated group exhibited engraftment of EBV-positive cells and tumor formation. Venetoclax treatment showed an insignificant trend to reducing IFN-γ levels in peripheral blood in established xenograft models. To our knowledge, this is the first report to suggest that venetoclax exerts not only anti-tumor effects but also potential anti-inflammatory effects in sCAEBV. BCL2 represents a promising therapeutic target to address the two pathological characteristics of sCAEBV: malignancy and inflammation.

Synergistic activity of S63845 and parthenolide to overcome acquired resistance to MEK1/2 inhibitor in melanoma cells: Mechanisms and therapeutic potential

Melanoma remains a global health challenge. While targeted therapy with BRAFV600/MEK inhibitors largely improved the survival and quality of life for advanced melanoma patients, most of them progress due to acquired resistance. Dynamic heterogeneity and phenotypic plasticity of resistant melanoma prompted us to use parthenolide, an agent with an assorted bioactivity profile in combination with agents targeting enhanced pro-survival capacity of resistant melanoma cells. Parthenolide was used in combination with S63845, ABT-263 and ABT-199, BH3-mimetics targeting anti-/pro-apoptotic protein interactions. These drug combinations were investigated in patient-derived drug-naïve melanoma cell lines, their trametinib-resistant counterparts displaying either dedifferentiation neural-crest-like phenotype (MITFlow/NGFRhigh) or differentiation phenotype (MITFhigh/NGFRlow), and trametinib-resistant cell lines undergoing the phenotype transition after trametinib withdrawal. While parthenolide reduces proliferation and increases senescent cell fraction accompanied with reduction of NF-κB activity and MITF expression, it does not trigger apoptosis in high percentages of melanoma cells. Combination of parthenolide with BH3-mimetics induces externalization of phosphatidylserine, most efficiently with S63845, an inhibitor of pro-survival MCL-1. Parthenolide and S63845 synergize to cause massive apoptosis regardless of melanoma cell phenotypes, which is associated with caspase-3/7 activation, H2AX phosphorylation, and PARP cleavage. Mechanistically, parthenolide combined with S63845 reduces the protein level of MCL-1, upregulates pro-apoptotic NOXA, and prevents S63845-induced reduction of NOXA protein. Collectively, massive apoptosis induced synergistically by parthenolide combined with S63845 in trametinib-resistant melanoma cells displaying various phenotypes justifies exploring the potential of this strategy as a future treatment option for patients with melanoma resistant to therapies targeting MAPK signaling.

Apoptosis regulators of the Bcl-2 family play a key role in chemoresistance of cholangiocarcinoma organoids

Cholangiocarcinoma (CCA) is a rare but devastating liver cancer which is commonly diagnosed at a late stage and often resistant to chemotherapy. Bcl-2 family members, which control apoptotic cell death, are known to be involved in the chemoresistance of some cancer types. This study investigated the role of Bcl-2 family members in the chemoresistance of cholangiocarcinoma organoids (CCAOs) in both undifferentiated and matured branching phenotypes (BRCCAOs). Patient-derived CCAOs and BRCCAOs were cultured to assess chemoresistance to an FDA-approved anticancer drug panel by testing cell viability using ATP quantification and apoptotic cell death by cleaved caspase 3 staining. More specifically, sensitivity to the first-line drug gemcitabine was tested in combination with Bcl-2 family inhibitors or activators. We found that in gemcitabine-resistant CCAOs, inhibition of Bcl-xl could overcome gemcitabine resistance and induce apoptotic cell death. Although inhibition of Mcl-1 or activation of Bax induced spontaneous cell death, this could not overcome gemcitabine resistance. The BRCCAOs, which mimic tumor architecture better than CCAOs, show broader chemoresistance to anticancer drugs. Of note, in the resistant BRCCAOs, Bcl-xl inhibition could restore gemcitabine sensitivity. In conclusion, this study shows that targeting Bcl-xl can overcome chemoresistance to gemcitabine in CCA organoids. CCAOs and BRCCAOs provide good preclinical models for testing new drug combinations and assessing personalized therapeutic approaches.

Design and in vitro evaluation of novel tetrazole derivatives of dianisidine as anticancer agents targeting Bcl-2 apoptosis regulator

This study examines the synthesis and biological evaluation of novel tetrazole derivatives of 3,3'-dimethoxybenzidine as potential anticancer agents, focusing on their cytotoxic, apoptotic, and anti-inflammatory properties. Ten derivatives were synthesized using thioureas as precursors, characterized through spectroscopic methods, and assessed for their in silico toxicological profiles using the ADMET-AI and ProTox 3.0 platforms. In vitro cytotoxic activity was evaluated against four human cancer cell lines (HTB-140, A549, HeLa, SW620) and one normal cell line (HaCaT) using MTT and LDH assays. Mechanistic studies included apoptosis assessment via flow cytometry and interleukin-6 (IL-6) analysis using ELISA. The synthesized tetrazole derivatives demonstrated significant anticancer potential, exhibiting selective cytotoxicity against cancer cell lines, robust induction of apoptosis, and a notable reduction in IL-6 levels. Their favorable toxicity profiles, as observed in both in silico and in vitro evaluations, support their potential as promising candidates for further development. The tested compounds showed strong inhibitory activity against the apoptosis regulator Bcl-2, with binding affinities comparable to those of native ligands. Western blot analysis revealed a dramatic loss of Bcl-2 protein expression in selected cancer cells during exposure to compound 5. Additionally, this research highlights the innovative use of hazardous substrates in drug discovery, aligning with the principles of green chemistry. Future efforts should focus on optimizing the most active derivatives and conducting in vivo studies to confirm their therapeutic potential and safety.

Development of a clinical prediction model for sensitivity to combination therapy of Bcl-2 inhibitors and hypomethylating agents in elderly/unfit patients with acute myeloid leukemia

OBJECTIVE

This study aims to develop a clinical prediction model for sensitivity to Bcl-2 inhibitors combined with hypomethylating agents (HMAs) in elderly/unfit patients with acute myeloid leukemia (AML).

METHODS

Clinical data, including French-American-British (FAB) classification, chromosomal karyotype, and second-generation sequencing results, were retrospectively collected from consecutive elderly/unfit patients with AML treated with Bcl-2 inhibitors in combination with HMAs between September 2019 and March 2024. Treatment efficacy was assessed in all patients. Logistic regression and Akaike information criterion were used to identify risk variables affecting efficacy. A nomogram was developed based on these variables to assess patient sensitivity to the treatment regimen. The performance of the nomogram was evaluated using a receiver operating characteristic (ROC) curve, calibration plot, and decision curve analysis (DCA).

RESULTS

This study included 209 patients with AML. The FAB classification, AML type, AML status, prior HMAs exposure, chromosomal karyotype, and mutations in ASXL1, FLT3, IDH, NPM1, and CEBPA were screened to develop the nomogram. The area under the ROC curve indicated a discriminatory power of 0.900 (95% CI, 0.860-0.941). The calibration curve suggested favorable concordance between the predicted and actual occurrence probabilities (P = 0.849). DCA revealed a net clinical benefit when the threshold probability ranged from 0 to 0.98. Internal validation, performed 500 times using the bootstrap method, demonstrated a satisfactory model performance in the validation set.

CONCLUSION

A prediction model was developed and validated to serve as a decision-making tool for physicians treating elderly/unfit patients with AML prior to initiating therapy with Bcl-2 inhibitors combined with HMAs.

A novel LncRNA risk model for disulfidptosis-related prognosis prediction and response to chemotherapy in acute myeloid leukemia

Acute myeloid leukemia (AML), the most prevalent acute leukemia in adults, is characterized by its heterogeneity, which contributes to a poor prognosis and high recurrence rate. Recently, a unique form of cell death, called disulfidptosis, has been identified, which could transforming our understanding of and strategy for cancer treatment. Consequently, further inquiry is necessary to explore the possible link between disulfidptosis and AML. To facilitate this analysis, the researchers obtained single-cell RNA sequencing (scRNA-seq) data from AML patients using the Gene Expression Omnibus (GEO) database. By applying the Cox proportional hazards model and least absolute shrinkage and selection operator (LASSO) regression analysis, we created a signature of disulfidptosis-related long non-coding RNAs (DRLs). This predictive model was established based on six specific DRLs (AC005076.1, AP002807.1, HDAC4-AS1, L3MBTL4-AS1, LINC01694, and THAP9-AS1). The utility of this model in forecasting the prognosis of AML patients was corroborated by the receiver operating characteristic (ROC) curve. Moreover, significant variations in the biological functions and signaling pathways were discovered by gene ontology (GO) and Gene Set Enrichment Analysis (GSEA). To further investigate the relationship between immune infiltration, the study assessed variations in immune checkpoint expression and immune cell subset infiltration. Additionally, we used real-time quantitative PCR (RT-qPCR) to detect lncRNA expression in AML and healthy control to substantiate our analysis results. In conclusion, the results of this study may help discover novel therapeutic targets and prognostic biomarkers for AML, paving the way for customized precision chemotherapy.

Phase II study of venetoclax added to bendamustine and obinutuzumab in patients with high-risk follicular lymphoma as front-line therapy: PrE0403

Over-expression of BCL-2 defines follicular lymphoma (FL). Venetoclax (VEN), a selective BCL-2 inhibitor, has previously been evaluated with bendamustine-based chemoimmunotherapy. VEN was given continuously, resulting in promising efficacy but unacceptable toxicity. The Phase II PrE0403 study was designed to evaluate intermittent dosing of VEN (10 days per cycle) combined with obinutuzumab and bendamustine (VEN-OB) in untreated FL subjects with high-risk features defined as a FLIPI-1 score of ≥3 and/or high tumor burden by GELF criteria. A total of 56 subjects were planned to be accrued with a goal of having 51 subjects eligible to improve the historical 50% CR rate to 65% with an 85% power and 15% type I error rate. Immunohistochemistry (IHC) expression of 3 antiapoptotic proteins (BCL-xL, MCL-1, and BCL-2) was performed and correlated with clinical outcomes. All 56 subjects were eligible and treated. CR rate was 41/56 (73.2%) and ORR was 52/56 (92.5%) meeting the primary endpoint. 2-year estimated PFS was 87.5% (90% CI: 75.3,93.9%) and 2-year estimated OS was 94.6% (90% CI: 86.7, 97.9%). However, the incidence of treatment-related adverse events ≥ grade 3 was 83.9% and serious adverse events were seen in 57.1%. After induction, atypical infections, including Grade 5 events, occurred. Anti-apoptotic protein expression by IHC was not correlated with clinical outcomes. Thus, while meeting the primary efficacy end point, VEN-OB is considered overly toxic in high-risk FL.

Unraveling Venetoclax Resistance: Navigating the Future of HMA/Venetoclax-Refractory AML in the Molecular Era

Acute myeloid leukemia (AML) has traditionally been linked to a poor prognosis, particularly in older patients who are ineligible for intensive chemotherapy. The advent of Venetoclax, a powerful oral BH3 mimetic targeting anti-apoptotic protein BCL2, has significantly advanced AML treatment. Its combination with the hypomethylating agent azacitidine (AZA/VEN) has become a standard treatment for this group of AML patients, demonstrating a 65% overall response rate and a median overall survival of 14.7 months, compared to 22% and 8 months with azacitidine monotherapy, respectively. However, resistance and relapses remain common, representing a significant clinical challenge. Recent studies have identified molecular alterations, such as mutations in FLT3-ITD, NRAS/KRAS, TP53, and BAX, as major drivers of resistance. Additionally, other factors, including metabolic changes, anti-apoptotic protein expression, and monocytic or erythroid/megakaryocytic differentiation status, contribute to treatment failure. Clinical trials are exploring strategies to overcome venetoclax resistance, including doublet or triplet therapies targeting IDH and FLT3 mutations; novel epigenetic approaches; menin, XPO1, and MDM2 inhibitors; along with immunotherapies like monoclonal antibodies and antibody-drug conjugates. A deeper understanding of the molecular mechanisms of resistance through single-cell analysis will be crucial for developing future therapeutic strategies.

Ciclosporin A potentiates venetoclax efficacy in FLT3-ITD AML by targeting the NFATC1-AKT-mTOR-BCL-2/MCL-1 signaling axis

The Fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutation in acute myeloid leukaemia (AML) is associated with adverse clinical outcomes, including poor prognosis, high relapse rates and reduced responses to conventional treatment regimens. While venetoclax (VEN) monotherapy has shown limited efficacy in FLT3-ITD AML due to intrinsic resistance mechanisms, this study demonstrates that ciclosporin A (CsA) synergistically enhances VEN's anti-leukaemic activity. CsA significantly suppresses cell proliferation, induces mitochondrial apoptosis and impairs mitochondrial bioenergetics in FLT3-ITD AML cells. Mechanistically, CsA enhances the effects of VEN through the downregulation of NFATC1, a critical regulator of the PI3K/AKT/mTOR signalling pathway. This suppression of NFATC1 leads to the coordinated downregulation of the anti-apoptotic proteins BCL-2 and MCL-1, thereby overcoming resistance and reinstating therapeutic susceptibility in FLT3-ITD AML.

Venetoclax confers synthetic lethality to chidamide in preclinical models with transformed follicular lymphoma

Transformed follicular lymphoma (t-FL) is an aggressive and heterogeneous hematological malignancy with limited treatment success; the development of novel therapeutic approaches is urgently needed for patients with t-FL. Here, we conducted high-throughput screening (HTS) and in vitro experiments using t-FL cell lines and primary samples to assess the synergistic effects of the histone deacetylase inhibitor chidamide and the BCL-2 inhibitor venetoclax. In vivo efficacy was further tested in xenograft models. The combination of venetoclax and chidamide significantly inhibited cell proliferation, induced apoptosis, and arrested the cell cycle in the G0/G1 phase across multiple t-FL cell lines. Furthermore, the combined therapy effectively reduced tumor burden, extended overall survival in xenograft models, and synergistically targeted patient samples, while sparing normal PBMCs. Mechanistically, this combination disrupted mitochondrial membrane potential and modulated the Wnt signaling pathway, as evidenced by decreased protein expression levels of Wnt3a, Wnt5a/b, β-catenin, and phosphorylated GSK3β. Concurrently, the combined regimen enhanced their respective anticancer effects by inhibiting the key genes HDAC10 and BCL-xL. Taken together, venetoclax combined with chidamide presents a potent anticancer strategy in preclinical models of t-FL and merits further exploration in clinical trials to validate its effectiveness and safety for treating t-FL.

IRF4 contributes to chemoresistance in IGH::BCL2-positive diffuse large B-cell lymphomas by mediating BCL2-induced SOX9 expression

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL), an aggressive type of non-Hodgkin's lymphoma, has a high relapse/refractory rate. We previously identified sex-determining region Y (SRY)-box transcription factor (SOX9) as a transcription factor that serves as a prognostic biomarker, particularly in BCL2-overexpressing DLBCL, and plays a vital role in lymphomagenesis. However, the molecular mechanisms that modulate the aberrant expression of SOX9 in this DLBCL subset remain unknown.

METHODS

Cell viability, apoptosis and cell cycle assays were performed to determine whether SOX9 contributes to DLBCL chemoresistance and rescues silencing IRF4-induced phenotypes. Protein‒protein interactions and protein ubiquitination were elucidated using immunoprecipitation, immunohistochemistry, immunofluorescence and immunoblotting. Chromatin immunoprecipitation sequencing (ChIP-seq), ChIP and dual-luciferase reporter assays were used to investigate IRF4 binding to the SOX9 promoter. The therapeutic potential of IRF4 inhibition was evaluated in vitro and in a mouse model of DLBCL xenografts.

RESULTS

SOX9 enhanced the resistance of the BCL2-overexpressing DLBCL subset to chemotherapy or a BCL2 inhibitor. Moreover, BCL2 inhibition downregulated SOX9 in an immunoglobulin heavy chain/BCL2-positive DLBCL subset. We further identified IRF4 as a key regulator of BCL2-induced SOX9 expression, and ChIP-seq confirmed that IRF4 is a key transcription factor for SOX9 in DLBCL. In addition, BCL2 promotes IRF4 entry into the nucleus by enhancing protein stability and downregulating proteasomal ubiquitination, thereby enforcing SOX9-mediated phenotypes. Finally, in a DLBCL cell line and xenografted mouse model, in vivo inhibition of IRF4 with an hIRF4 antisense oligonucleotide repressed lymphomagenesis and DLBCL chemoresistance.

CONCLUSIONS

Our data support the conclusion that IRF4 plays an essential role in BCL2-induced upregulation of SOX9 expression, and targeting IRF4 may represent a promising therapeutic strategy to cure relapsed and refractory DLBCL.

KEYPOINTS/HIGHLIGHTS

BCL2 activated IRF4 by enhancing its nuclear activity to induce sex-determining region Y (SRY)-box 9 protein (SOX9) aberrant expression, which is a critical pathway for drug resistance in BCL2-overexpressing diffuse large B-cell lymphoma (DLBCL). Targeting IRF4 may be worth investigating further regarding its potential to overcome the chemoresistance of BCL2-overexpressing DLBCL to standard therapies.

Metabolism and therapeutic response in acute myeloid leukemia with IDH1/2 mutations

Pathogenic variants of isocitrate dehydrogenase 1 and 2 (IDH1/2) genes are present in approximately 20% of acute myeloid leukemia (AML) cases, resulting in the oncometabolite R-2-hydroxyglutarate (R-2-HG). The accumulation of R-2-HG in leukemic cells and in their niche induces epigenetic modifications, profound rewiring of the cellular metabolism, and microenvironmental remodeling. These changes promote cellular differentiation bias, enhancing the survival and proliferation of leukemic cells, and thus playing a pivotal role in leukemogenesis and resistance to standard AML therapy. This review focuses on the different perspectives offered by studying metabolism and resistance to standard treatments in AML with IDH1 or IDH2 pathogenic variants, for the development of new biomarkers and therapeutic solutions.

The challenge of targeting key drivers of CLL and sequencing therapy in an era of experimental therapeutics

Treatment of chronic lymphocytic leukemia (CLL) has been revolutionized with the introduction of small molecule inhibitors targeting both the B-cell receptor (BCR) signaling pathway and B-cell lymphoma-2 (BCL-2) family of proteins. Inhibitors of Bruton's tyrosine kinase (BTK) and the BH3 mimetic venetoclax are bothcurrently used as the standard of care for patients in the frontline and relapsed/refractory setting of CLL. With the clinical success of both these classes of therapies, sequencing of these agents has become a major challenge in treatment of CLL. In this review we will discuss the current data available for both classes of agents in the front-line and relapsed/refractor setting, considerations when giving these agents, and how we can continue to improve the treatment landscape for CLL.

Augmenting the Anti-Leukemic Activity of the BCL-2 Inhibitor Venetoclax Through Its Transformation Into Polypharmacologic Dual BCL-2/HDAC1 and Dual BCL-2/HDAC6 Inhibitors

Motivated by the anti-leukemic synergy between histone deacetylase (HDAC) inhibitors and the FDA-approved BCL-2 inhibitor venetoclax, coupled with our interests in polypharmacology, we sought to bolster the anti-leukemic efficacy of the clinical drug by grafting HDAC1-selective or HDAC6-selective inhibitor motifs onto a solvent-accessible domain of venetoclax. We discovered multiple polypharmacological agents that both retained the potent BCL-2 inhibitory activity of venetoclax and effectively inhibited either HDAC1 or HDAC6 with excellent (up to 80-fold) selectivities for the desired HDAC isoform. In addition, relative to parental venetoclax, two of our lead compounds, BD-4-213 and AMC-4-154, exhibited superior activities against the acute myeloid leukemia cell line MV4;11 and an MV4;11 cell line engineered to overexpress BCL-2. Annexin-V assay results confirmed an on-target mechanism of apoptosis for these novel chimeric molecules. Efforts to further boost the HDAC1 or HDAC6 binding affinities and/or selectivities proved unsuccessful due to synthetic chemistry challenges and solubility problems, which may underscore the difficulties of polypharmacology approaches involving a large inhibitor, such as venetoclax.

Integrated Genomics Reveal Potential Resistance Mechanisms of PANoptosis-Associated Genes in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is marked by the proliferation of abnormal myeloid progenitor cells in the bone marrow and blood, leading to low cure rates despite new drug approvals from 2017 to 2018. Current therapies often fail due to the emergence of drug resistance mechanisms, such as those involving anti-apoptotic pathways and immune evasion, highlighting an urgent need for novel approaches to overcome these limitations. Programmed cell death (PCD) is crucial for tissue homeostasis, with PANoptosis-a form of PCD integrating pyroptosis, apoptosis, and necroptosis-recently identified. This process, regulated by the PANoptosome complex, could be key to overcoming AML drug resistance. Targeting multiple PCD pathways simultaneously may prove more effective than single-target therapies. Research suggests that disrupting anti-apoptotic mechanisms, such as those involving Bcl-2, can enhance drug sensitivity in AML. This study hypothesizes that PANoptosis-associated resistance genes (PARGs) play a critical role in AML drug resistance by modulating immune responses and offers a multi-faceted approach to tackle this challenge. Using RNA sequencing data from the Cancer Genome Atlas and Gene Expression Omnibus databases, we performed differential expression analysis to identify significantly dysregulated PARGs in AML. Regression analysis identified prognostic PARGs, bridging a key gap in understanding how these genes contribute to treatment resistance. We then verified their expression in AML cell lines and cell samples treated with cytarabine using RT-qPCR. Hierarchical clustering revealed distinct PARG expression patterns, and functional enrichment analysis highlighted their involvement in immune-related pathways. The combination of bioinformatics and experimental validation underscores how these genes may mediate immune modulation in drug resistance, providing a robust framework for further study. Our findings suggest that PARGs contribute to AML resistance by modulating immune responses and provide potential targets for therapeutic intervention. This study highlights the potential of targeting PARGs to improve treatment outcomes in AML. By analyzing the expression changes of these genes in response to standard clinical treatments, we provide a framework for developing multi-target therapeutic strategies that simultaneously disrupt multiple programmed cell death pathways. Such an approach directly addresses the limitations of current treatments by offering a method to enhance drug sensitivity and mitigate resistance, potentially improving survival rates. Our findings underscore the importance of a comprehensive understanding of PCD mechanisms and pave the way for innovative treatments that could significantly impact AML management.

Anticancer Potential of Cymbopogon citratus L. Essential Oil: In Vitro and In Silico Insights into Mitochondrial Dysfunction and Cytotoxicity in Cancer Cells

This study aims to assess the potential anticancer activity of lemongrass essential oil (LEO) using in vitro and in silico methods. The steam hydrodistillation of the aerial parts yielded 3.2% (wt) LEO. The GC-MS analysis of the LEO revealed the presence of α-citral (37.44%), β-citral (36.06%), linalool acetate (9.82%), and d-limonene (7.05%) as major components, accompanied by several other minor compounds. The antioxidant activity, assessed using the DPPH assay, revealed that LEO exhibits an IC50 value of 92.30 μg/mL. The cytotoxic effect of LEO, as well as LEO solubilized with Tween-20 (LEO-Tw) and PEG-400 (LEO-PEG), against a series of cancer cell lines (A375, RPMI-7951, MCF-7, and HT-29) was assessed using the Alamar Blue assay; the results revealed a high cytotoxic effect against all cell lines used in this study. Moreover, neither one of the tested concentrations of LEO, LEO-PG, or LEO-TW significantly affected the viability of healthy HaCaT cells, thus showing promising selectivity characteristics. Furthermore, LEO, LEO-PG, and LEO-TW increased ROS production and decreased the mitochondrial membrane potential (MMP) in all cancer cell lines. Moreover, LEO treatment decreased all mitochondrial respiratory rates, thus suggesting its ability to induce impairment of mitochondrial function. Molecular docking studies revealed that LEO anticancer activity, among other mechanisms, could be attributed to PDK1 and PI3Kα, where the major contributors are among the minor components of the essential oil. The highest active theoretical inhibitor against both proteins was β-caryophyllene oxide.

The value of coimmunoprecipitation (Co-IP) assays in drug discovery

INTRODUCTION

Co-IP assays are well-established technologies widely applicated for investigating the mechanisms underlying protein-protein interactions and identifying protein-protein interaction modulators. These assays play an important role in elucidating the complex networks of protein interactions critical for cellular functions.

AREAS COVERED

This review covers a technical protocol of standard Co-IP. The research contents and conclusions of Co-IP in protein-protein interactions and protein-protein interaction modulators are summarized. Finally, three derivations of Co-IP assays are introduced. Literature was surveyed from original publications, standard sources, PubMed and clinical trials through 14 April 2025.

EXPERT OPINION

To perform Co-IP successfully, researchers must consider the selection of specific antibody, remission of nonspecific binding and detection limitations for transient or weak interactions. Co-IP assays offer several advantages over tandem affinity purification and pull-down methods, particularly in their applicability to primary cells. This allows for the study of PPIs in a natural cellular environment. Conventional Co-IP assays often struggle to detect weak or transient interactions and can suffer from nonspecific binding contamination. However, advancements in Co-IP techniques address these challenges, enhancing sensitivity and specificity, and enabling the detection of subtle interactions while distinguishing specific binding events. This makes Co-IP a powerful tool for exploring the dynamics of protein interactions in living systems.

Stromal lipid species dictate melanoma metastasis and tropism

Cancer cells adapt to signals in the tumor microenvironment (TME), but the TME cues that impact metastasis and tropism are still incompletely understood. We show that abundant stromal lipids from young subcutaneous adipocytes, including phosphatidylcholines, are taken up by melanoma cells, where they upregulate melanoma PI3K-AKT signaling, fatty acid oxidation, oxidative phosphorylation (OXPHOS) leading to oxidative stress, resulting in decreased metastatic burden. High OXPHOS melanoma cells predominantly seed the lung and brain; decreasing oxidative stress with antioxidants shifts tropism from the lung to the liver. By contrast, the aged TME provides fewer total lipids but is rich in ceramides, leading to lower OXPHOS and high metastatic burden. Aged TME ceramides taken up by melanoma cells activate the S1P-STAT3-IL-6 signaling axis and promote liver tropism. Inhibiting OXPHOS in the young TME or blocking the IL-6 receptor in the aged TME reduces the age-specific patterns of metastasis imposed by lipid availability.

Targeting BCL2 in Waldenström macroglobulinemia: from biology to treatment management

Despite recent advances in the treatment of Waldenström macroglobulenimia (WM), including the development of Bruton tyrosine kinase inhibitors (BTKis), the disease remains incurable highlighting the urgent need for new treatments. The overexpression of BCL2 in WM cells promotes cell survival by resisting apoptosis and contributes to resistance to chemotherapy and targeted therapies. Concurrently, Bcl2 proteins that are encoded by oncogenes supporting cell survival are frequently upregulated in WM, even in the presence of DNA-damaging agents, and hence have emerged as an alternative therapeutic target. Venetoclax serves as a novel orally administered small agent that targets Bcl-2 protein by acting as a BCL2 homology domain 3 (BH3) mimetic and has shown promising results in WM patients, including those previously treated with BTKis. Furthermore, venetoclax, in combination with standard WM regimens, has shown enhanced activity, but further studies are required to elucidate the mechanism of its synergistic action and identify the patients who can benefit from the combined therapy. New BCL2 inhibitors are in advanced stages of clinical development and may offer additional options. The present review will focus on the current knowledge we have on BCL2 inhibitors in WM, the input of these compounds "from bench to bedside," and their utility in managing relapsed/refractory WM patients.

Understanding and Targeting Metabolic Vulnerabilities in Acute Myeloid Leukemia: An Updated Comprehensive Review

Acute Myeloid Leukemia (AML) is characterized by aggressive proliferation and metabolic reprogramming that support its survival and resistance to therapy. This review explores the metabolic distinctions between AML cells and normal hematopoietic stem cells (HSCs), emphasizing the role of altered mitochondrial function, oxidative phosphorylation (OXPHOS), and biosynthetic pathways in leukemic progression. AML cells exhibit distinct metabolic vulnerabilities, including increased mitochondrial biogenesis, reliance on glycolysis and amino acid metabolism, and unique signaling interactions that sustain leukemic stem cells (LSCs). These dependencies provide potential therapeutic targets, as metabolic inhibitors have demonstrated efficacy in disrupting AML cell survival while sparing normal hematopoietic cells. We examine current and emerging metabolic therapies, such as inhibitors targeting glycolysis, amino acid metabolism, and lipid biosynthesis, highlighting their potential in overcoming drug resistance. However, challenges remain in translating these strategies into clinical practice due to AML's heterogeneity and adaptability. Further research into AML's metabolic plasticity and precision medicine approaches is crucial for improving treatment outcomes. Understanding and exploiting AML's metabolic vulnerabilities could pave the way for novel, more effective therapeutic strategies.

Impact of mitochondrial metabolism on T-cell dysfunction in chronic lymphocytic leukemia

T cells play a central role in anti-tumor immunity, yet their function is often compromised within the immunosuppressive tumor microenvironment, leading to cancer progression and resistance to immunotherapies. T-cell activation and differentiation require dynamic metabolic shifts, with mitochondrial metabolism playing a crucial role in sustaining their function. Research in cancer immunometabolism has revealed key mitochondrial abnormalities in tumor-infiltrating lymphocytes, including reduced mitochondrial capacity, depolarization, structural defects, and elevated reactive oxygen species. While these mitochondrial disruptions are well-characterized in solid tumors and linked to T-cell exhaustion, their impact on T-cell immunity in lymphoproliferative disorders remains underexplored. Chronic lymphocytic leukemia (CLL), the most prevalent chronic adult leukemia, is marked by profound T-cell dysfunction that limits the success of adoptive cell therapies. Emerging studies are shedding light on the role of mitochondrial disturbances in CLL-related T-cell dysfunction, but significant knowledge gaps remain. This review explores mitochondrial metabolism in T-cell exhaustion, emphasizing recent findings in CLL. We also discuss therapeutic strategies to restore T-cell mitochondrial function and identify key research gaps.

Main methods and tools for peptide development based on protein-protein interactions (PPIs)

Protein-protein interactions (PPIs) regulate essential physiological and pathological processes. Due to their large and shallow binding surfaces, PPIs are often considered challenging drug targets for small molecules. Peptides offer a viable alternative, as they can bind these targets, acting as regulators or mimicking interaction partners. This review focuses on competitive peptides, a class of orthosteric modulators that disrupt PPI formation. We provide a concise yet comprehensive overview of recent advancements in in-silico peptide design, highlighting computational strategies that have improved the efficiency and accuracy of PPI-targeting peptides. Additionally, we examine cutting-edge experimental methods for evaluating PPI-based peptides. By exploring the interplay between computational design and experimental validation, this review presents a structured framework for developing effective peptide therapeutics targeting PPIs in various diseases.

Binding-Site Purification of Actives (B-SPA) Enables Efficient Large-Scale Progression of Fragment Hits by Combining Multi-Step Array Synthesis With HT Crystallography

Fragment approaches are long-established in target-based ligand discovery, yet their full transformative potential lies dormant because progressing the initial weakly binding hits to potency remains a formidable challenge. The only credible progression paradigm involves multiple cycles of costly conventional design-make-test-analyse medicinal chemistry. We propose an alternative approach to fragment elaboration, namely performing large numbers of parallel and diverse automated multiple step reactions, and evaluating the binding of the crude reaction products by high-throughput protein X-ray crystallography. We show it is effective and low-cost to perform, in parallel, large numbers of non-uniform multi-step reactions, because, even without compound purification, crystallography provides a high-quality readout of binding. This can detect low-level binding of weakly active compounds, which the target binding site extracts directly from crude reaction mixtures. In this proof-of-concept study, we have expanded a fragment hit, from a crystal-based screen of the second bromodomain of pleckstrin homology domain-interacting protein (PHIP(2)), using array synthesis on low-cost robotics. We were able to implement 6 independent multi-step reaction routes of up to 5 steps, attempting the synthesis of 1876 diverse expansions, designs entirely driven by synthetic tractability. The expected product was present in 1108 (59%) crude reaction mixtures, detected by liquid chromatography mass spectrometry (LCMS). 22 individual products were resolved in the crystal structures of crude reaction mixtures added to crystals, providing an initial structure activity relationship map. 19 of these showed binding pose stability, while, through binding instability in the remaining 3 products, we could resolve a stereochemical preference for mixtures containing racemic compounds. One compound showed biochemical potency (IC50=34 μM) and affinity (Kd=50 μM) after resynthesis. This approach therefore lends itself to routine fragment progression, if coupled with algorithmically guided compound and reaction design and new formalisms for data analysis.

The BCL-2 protein family: from discovery to drug development

The landmark discovery of the BCL-2 gene and then its function marked the identification of inhibition of apoptotic cell death as a crucial novel mechanism driving cancer development and launched the quest to discover the molecular control of apoptosis. This work culminated in the generation of specific inhibitors that are now in clinical use, saving and improving tens of thousands of lives annually. Here, some of the original players of this story, describe the sequence of critical discoveries. The t(14;18) chromosomal translocation, frequently observed in follicular lymphoma, allowed the identification and the cloning of a novel oncogene (BCL-2) juxtaposed to the immunoglobulin heavy chain gene locus (IgH). Of note, BCL-2 acted in a distinct manner as compared to then already known oncogenic proteins like ABL and c-MYC. BCL-2 did not promote cell proliferation but inhibited cell death, as originally shown in growth factor dependent haematopoietic progenitor cell lines (e.g., FDC-P1) and in Eμ-Myc/Eμ-Bcl-2 double transgenic mice. Following a rapid expansion of the BCL-2 protein family, the Abbott Laboratories solved the first structure of BCL-XL and subsequently the BCL-XL/BAK peptide complex, opening the way to understanding the structures of other BCL-2 family members and, finally, to the generation of inhibitors of the different pro-survival BCL-2 proteins, thanks to the efforts of Servier/Norvartis, Genentech/WEHI, AbbVie, Amgen, Prelude and Gilead. Although the BCL-2 inhibitor Venetoclax is in clinical use and inhibitors of BCL-XL and MCL-1 are undergoing clinical trials, several questions remain on whether therapeutic windows can be achieved and what other agents should be used in combination with BH3 mimetics to achieve optimal therapeutic impact for cancer therapy. Finally, the control of the expression of BH3-only proteins and pro-survival BCL-2 family members needs to be better understood as this may identify novel targets for cancer therapy. This story is still not concluded!

Re-appraising assays on permeabilized blood cancer cells testing venetoclax or other BH3 mimetic agents selectively targeting pro-survival BCL2 proteins

BH3 mimetic drugs that selectively target the pro-survival BCL2 proteins are highly promising for cancer treatment, most notably for treating blood cancers. Venetoclax, which inhibits BCL2, is now approved for treating chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML). Preferably, robust and validated assays would identify patients most likely to benefit from therapy with venetoclax itself or with inhibitors of other pro-survival proteins. A sophisticated method that has been developed is the BH3 profiling assay. In this assay, permeabilized, instead of intact, cells are treated for a few hours with inhibitors of the pro-survival BCL2 proteins, and the resultant mitochondrial depolarization measured. Sensitivity to a specific inhibitor (e.g., venetoclax or other BH3 mimetics) is then used to infer the reliance of a tumor (e.g., CLL) on one or more pro-survival BCL2 proteins. However, we found that this methodology cannot reliably identify such dependencies. In part, this is because almost all cells express multiple pro-survival BCL2 proteins that restrain BAX and BAK which must be inhibited before mitochondrial depolarization and apoptosis can proceed. Using genetic and pharmacological tools across multiple cell line models of blood cancer, we demonstrated that selective BCL2 inhibitors have important flow-on effects that includes the redistribution of BH3-only proteins to ancillary pro-survival proteins not directly engaged by the inhibitor. These secondary effects, critical to the biological action of selective inhibitors, were not accurately recapitulated in permeabilized cells, probably due to the limited time frame possible in such assays or the altered biophysical conditions when cells are permeabilized. While we could consistently define the sensitivity of a tumor cell to a particular BH3 mimetic drugs using intact cells, this was not reliable with permeabilized cells. These studies emphasize the need to carefully evaluate assays on permeabilized cells undertaken with inhibitors of the pro-survival BCL2 proteins.

The First Chalcone Derivatives of Valine-Based Spiro-Cyclotriphosphazenes: In Vitro Cytotoxic Properties, Molecular Docking and DNA Damage Mechanism Studies

Cancer treatment requires novel compounds with potent cytotoxic and genotoxic properties to effectively target cancer cells. In this study, new hybrid cyclotriphosphazene compounds were synthesized, characterized, and evaluated for their biological activity. Cytotoxicity against A2780 and Caco-2 cancer cell lines was assessed via the MTT assay, while genotoxic effects at 60-70% cell viability were examined using the Comet assay. Apoptotic cells were identified through TUNEL analyses, and reactive oxygen species levels were measured. Results showed that these compounds significantly reduced cell viability through DNA damage mechanisms. At high doses (50-100 µM), BV, BVK1, BVK2, and BVK4 decreased A2780 cell viability by 30-65%, whereas VPA had a milder effect (15-25%). In Caco-2 cells, viability was reduced by 10-35%. The compounds exhibited varying cytotoxicity across different cancer cell lines, reflecting cancer cell heterogeneity. Significant DNA damage, including changes in tail length, tail density, and tail moment, was observed in A2780 cells, confirming cell death via DNA damage. Molecular docking analyses further supported the potential of cyclotriphosphazene compounds (BV and BVK2) as targeted cancer inhibitors. Molecular docking revealed BVK2's high selectivity for Bcl-2, mutant p53, and VEGFR2. BVK2 and BV demonstrate strong binding affinities with key cancer-related targets, indicating their potential as multi-targeted inhibitors that regulate apoptosis, cell cycle control, and angiogenesis, making them promising candidates for targeted cancer therapy.

Mcl-1 is an important target protein for kaempferol from persimmon leaves in sensitizing ABT-199 to induce apoptosis in hepatoma cancer cells

Overexpression of Mcl-1 causes hepatocellular carcinoma resistance to Bcl-2 inhibitors, but there are currently no direct Mcl-1 inhibitors available for clinical application. Our previous research demonstrated that kaempferol from persimmon leaves (KPL) can sensitize ABT-199 to inhibit liver cancer cell proliferation. This study further explored the effect of KPL sensitizing ABT-199 on liver cancer cell apoptosis and its potential mechanisms. The inhibitory effects of KPL and ABT-199, both individually and in combination, on the proliferation of HepG2, Huh7, and HCCLM3 cells were evaluated. Cell apoptosis and mitochondrial morphology were assessed with flow cytometry and confocal microscopy, respectively. Apoptosis and changes in Mcl-1 protein expression were evaluated after siMcl-1 knockdown. Molecular docking simulations were used to analyze the interactions of KPL and ABT-199, both individually and in combination, with Mcl-1 protein. The effect of KPL on Mcl-1 stability was investigated with proteasome inhibitor MG132. The results demonstrated that KPL showed a strong sensitizing effect on ABT-199 (CI value < 1), enhanced liver cancer cell proliferation inhibition and increased apoptosis rate. Combined treatment led to mitochondrial fragmentation and swelling, and significantly reduced Mcl-1 expression. siMcl-1 interference resulted in little difference in apoptosis rates and Mcl-1 expression between the combination treatment and untreated groups. Molecular docking revealed that KPL increased the affinity of ABT-199 for Mcl-1, whereas MG132 prevented KPL from downregulating Mcl-1 expression. These findings suggest that KPL enhances ABT-199-induced apoptosis in HCC cells by targeting Mcl-1 protein through increasing the affinity between ABT-199 and Mcl-1, while also promoting Mcl-1 degradation by affecting post-translational modifications.

Proinflammatory cytokines sensitise mesenchymal stromal cells to apoptosis

Mesenchymal stromal cells (MSCs) exert broad therapeutic effects across a range of inflammatory diseases. Their mechanism of action has largely been attributed to paracrine signalling, orchestrated by an array of factors produced by MSCs that are collectively termed the "secretome". Strategies to enhance the release of these soluble factors by pre-exposure to inflammatory cytokines, a concept known as "licensing", is thought to provide a means of enhancing MSC efficacy. Yet, recent evidence shows that intravenously infused MSCs entrapped within the lungs undergo apoptosis, and their subsequent clearance by host phagocytes is essential for their therapeutic efficacy. We therefore sought to clarify the mechanisms governing regulated cell death in MSCs and how exposure to inflammatory cytokines impacts this process. Our results show that MSCs are relatively resistant to cell death induced via the extrinsic pathway of apoptosis, as well as stimuli that induce necroptosis, a form of regulated inflammatory cell death. Instead, efficient killing of MSCs required triggering of the mitochondrial pathway of apoptosis, via inhibition of the pro-survival proteins MCL-1 and BCL-XL. Apoptotic bodies were readily released by MSCs during cell disassembly, a process that was inhibited in vitro and in vivo when the apoptotic effectors BAK and BAX were genetically deleted. Licensing of MSCs by pre-exposure to the inflammatory cytokines TNF and IFN-γ increased the sensitivity of MSCs to intrinsic apoptosis in vitro and accelerated their in vivo clearance by host cells within the lungs after intravenous infusion. Taken together, our study demonstrates that inflammatory "licensing" of MSCs facilitates cell death by increasing their sensitivity to triggers of the intrinsic pathway of apoptosis and accelerating the kinetics of apoptotic cell disassembly.

Drugging Challenging Cancer Targets Using Fragment-Based Methods

There are many highly validated cancer targets that are difficult or impossible to drug due to the absence of suitable pockets that can bind small molecules. Fragment-based methods have been shown to be a useful approach for identifying ligands to proteins that were previously thought to be undruggable. In this review, I will give an overview of fragment-based ligand discovery and provide examples from our own work on how fragment-based methods were used to discover high affinity ligands for challenging cancer drug targets.

The BCL2 family: from apoptosis mechanisms to new advances in targeted therapy

The B cell lymphoma 2 (BCL2) protein family critically controls apoptosis by regulating the release of cytochrome c from mitochondria. In this cutting-edge review, we summarize the basic biology regulating the BCL2 family including canonical and non-canonical functions, and highlight milestones from basic research to clinical applications in cancer and other pathophysiological conditions. We review laboratory and clinical development of BH3-mimetics as well as more recent approaches including proteolysis targeting chimeras (PROTACs), antibody-drug conjugates (ADCs) and tools targeting the BH4 domain of BCL2. The first BCL2-selective BH3-mimetic, venetoclax, showed remarkable efficacy with manageable toxicities and has transformed the treatment of several hematologic malignancies. Following its success, several chemically similar BCL2 inhibitors such as sonrotoclax and lisaftoclax are currently under clinical evaluation, alone and in combination. Genetic analysis highlights the importance of BCL-XL and MCL1 across different cancer types and the possible utility of BH3-mimetics targeting these proteins. However, the development of BH3-mimetics targeting BCL-XL or MCL1 has been more challenging, with on-target toxicities including thrombocytopenia for BCL-XL and cardiac toxicities for MCL1 inhibitors precluding clinical development. Tumor-specific BCL-XL or MCL1 inhibition may be achieved by novel targeting approaches using PROTACs or selective drug delivery strategies and would be transformational in many subtypes of malignancy. Taken together, we envision that the targeting of BCL2 proteins, while already a success story of translational research, may in the foreseeable future have broader clinical applicability and improve the treatment of multiple diseases.

Novel selective strategies targeting the BCL-2 family to enhance clinical efficacy in ALK-rearranged non-small cell lung cancer

ALK (anaplastic lymphoma kinase) rearrangements represent the third most predominant driver oncogene in non-small cell lung cancer (NSCLC). Although ALK inhibitors are the tyrosine kinase inhibitors (TKIs) with the longest survival rates in lung cancer, the complex systemic clinical evaluation and the apoptotic cell death evasion of drug-tolerant persister (DTP) cancer cells may limit their therapeutic response. We found that dynamic BH3 profiling (DBP) presents an excellent predictive capacity to ALK-TKIs, that would facilitate their use in a clinical setting and complementing the readout of standard diagnostic assays. In addition, we revealed novel acute adaptive mechanisms in response to ALK inhibitors in cell lines and patient-derived tumor cells. Consistently, all our cell models confirmed a rapid downregulation of the sensitizer protein NOXA, leading to dependence on the anti-apoptotic protein MCL-1 after treatment with ALK-TKIs. In some cases, the anti-apoptotic protein BCL-xL may contribute equally to this anti-apoptotic response. Importantly, these acute dependencies could be prevented with BH3 mimetics in vitro and in vivo, blocking tumor adaptation to treatment. Finally, we also demonstrated how dual reactivation of PI3K/AKT and MAPK signaling pathways can impair lorlatinib response, which could be overcome with specific inhibitors of both signaling pathways. In conclusion, our findings propose several therapeutic combinations that should be explored in future clinical trials to enhance ALK inhibitors efficacy and improve the clinical response in a broad NSCLC patient population.

A First-in-Class Dual Degrader of Bcl-2/Bcl-xL Reverses HIV Latency and Minimizes Ex Vivo Reservoirs from Patients

The persistence of latent HIV-1 proviruses in CD4+ T cells is a major obstacle to curing HIV. The "shock and kill" strategy involves reversing latency with latency-reversing agents (LRAs) and selectively inducing cell death in infected cells. However, current LRAs have shown limited efficacy in eliminating the ex vivo HIV reservoir and thus failed in clinical study. In this study, we repurposed PZ703b, a pro-apoptotic protein degrader initially developed for anti-leukemia therapy, to target HIV eradication. PZ703b induced the degradation of Bcl-2 and Bcl-xL, activating the non-canonical NF-kB pathway and caspases cascade, resulting in latency reversal and the selective apoptosis of infected cells. The treatment of ex vivo CD4+ T cells from ART-suppressed HIV-1 patients led to approximately a 50% reduction in the replication-competent reservoir. While this result does not reach the threshold required for a complete cure, it demonstrates the potential of a dual degrader of Bcl-2/Bcl-xL in reversing HIV latency and inducing selective cell death. Our study provides a proof-of-concept for using dual degraders of Bcl-2/Bcl-xL as a novel category of LRAs in therapeutic strategies aimed at reducing HIV reservoirs. This approach may pave the way for the further exploration of targeted interventions to eliminate the HIV-inducible reservoir.

Fisetin as a Blueprint for Senotherapeutic Agents - Elucidating Geroprotective and Senolytic Properties with Molecular Modeling

Targeting senescent cells and the factors that accelerate this pathological state has recently emerged as a novel field in medicinal chemistry. As attention shifts to synthetic substances, studies on natural agents are often overlooked. In this paper, we present a detailed computational modeling study that encompasses quantum mechanics and molecular dynamics to elucidate the senotherapeutic activity of fisetin, a natural flavonoid. The mitochondrial environment, serving as a proxy for senescence, received special attention. Throughout the study, fisetin's outstanding geroprotective properties-exhibiting significant potential against ⋅OOH, O2⋅-, and ⋅OH radicals, surpassing those of Trolox or ascorbate-were identified. Furthermore, fisetin demonstrated a high capacity to restore oxidatively damaged biomolecules to their pristine forms, thereby renewing the functionality of proteins and amino acids. The senolytic properties were examined in terms of Bcl-2 and Bcl-xL inhibition. The results indicated that fisetin not only binds effectively to these proteins but also, with appropriate modifications, may exhibit specific selectivity toward either target. This study highlights fisetin's remarkable activity in these areas and provides a molecular description of the underlying processes, paving the way for future research.

Both direct and indirect suppression of MCL1 synergizes with BCLXL inhibition in preclinical models of gastric cancer

Despite the progress of treatment in gastric cancer (GC), the overall outcomes remain poor in patients with advanced diseases, underscoring the urgency to develop more effective treatment strategies. BH3-mimetic drugs, which inhibit the pro-survival BCL2 family proteins, have demonstrated great therapeutic potential in cancer therapy. Although previous studies have implicated a role of targeting the cell survival pathway in GC, the contribution of different pro-survival BCL2 family proteins in promoting survival and mediating resistance to current standard therapies in GC remains unclear. A systematic study to elucidate the hierarchy of these proteins using clinically more relevant GC models is essential to identify the most effective therapeutic target(s) and rational combination strategies for improving GC therapy. Here, we provide evidence from both in vitro and in vivo studies using a broad panel of GC cell lines, tumoroids, and xenograft models to demonstrate that BCLXL and MCL1, but not other pro-survival BCL2 family proteins, are crucial for GC cells survival. While small molecular inhibitors of BCLXL or MCL1 exhibited some single-agent activity, their combination sufficed to cause maximum killing. However, due to the unsolved cardiotoxicity associated with direct MCL1 inhibitors, finding combinations of agents that indirectly target MCL1 and enable the reduction of doses of BCLXL inhibitors while maintaining their anti-neoplastic effects is potentially a feasible approach for the further development of these compounds. Importantly, inhibiting BCLXL synergized significantly with anti-mitotic and HER2-targeting drugs, leading to enhanced anti-tumour activity with tolerable toxicity in preclinical GC models. Mechanistically, anti-mitotic chemotherapies induced MCL1 degradation via the ubiquitin-proteasome pathway mainly through FBXW7, whereas HER2-targeting drugs suppressed MCL1 transcription via the STAT3/SRF axis. Moreover, co-targeting STAT3 and BCLXL also exhibited synergistic killing, extending beyond HER2-amplified GC. Collectively, our results provide mechanistic rationale and pre-clinical evidence for co-targeting BCLXL and MCL1 (both directly and indirectly) in GC. (i) Gastric cancer cells rely on BCLXL and, to a lesser degree, on MCL1 for survival. The dual inhibition of BCLXL and MCL1 with small molecular inhibitors acts synergistically to kill GC cells, regardless of their TCGA molecular subtypes or the presence of poor prognostic markers. While the effect of S63845 is mediated by both BAX and BAK in most cases, BAX, rather than BAK, acts as the primary mediator of BCLXLi in GC cells. (ii) Inhibiting BCLXL significantly synergizes with anti-mitotic and HER2-targeting drugs, leading to enhanced anti-tumour activity with tolerable toxicity in preclinical GC models. Mechanistically, anti-mitotic chemotherapies induce MCL1 degradation via the ubiquitin-proteasome pathway mainly through FBXW7, whereas HER2-targeting drugs suppress MCL1 transcription via the STAT3/SRF axis. The combination of the STAT3 inhibitor and BCLXL inhibitor also exhibits synergistic killing, extending beyond HER2-amplified GC.

The polypharmacy combination of the BCL-2 inhibitor venetoclax (VEN) and the FLT3 inhibitor gilteritinib (GIL) is more active in acute myeloid leukemia cells than novel polypharmacologic BCL-2/FLT3 VEN-GIL hybrid single-molecule inhibitors

Current treatments for acute myeloid leukemias (AMLs) cure fewer than 30 % of patients. This low efficacy is due, in part, to the inter-patient and intra-patient heterogeneity of AMLs; accordingly, all current AML treatment regimens involve drug combinations (polypharmacy). A recently-completed clinical trial in relapsed/refractory AML using a combination of two newer targeted antileukemics, the BCL-2 inhibitor venetoclax (VEN) plus the FLT3 inhibitor gilteritinib (GIL), yielded highly promising results for this two-drug polypharmacy combination. Polypharmacology - wherein a single drug molecule that inhibits two or more biological targets is created - has been proposed to offer superior therapeutic results, as compared to the corresponding polypharmacy approach. Herein, we designed and synthesized several polypharmacologic dual BCL-2/FLT3 hybrid single-molecule inhibitors by tethering VEN to GIL, through their solvent-exposed domains. While the in vitro antileukemic activity of the two-drug VEN + GIL polypharmacy combination proved superior to our focused library of VEN-GIL hybrids, alternative grafting points on GIL may yield improved results for future hybrid compounds.

A BCL-xL/BCL-2 PROTAC effectively clears senescent cells in the liver and reduces MASH-driven hepatocellular carcinoma in mice

Accumulation of senescent cells (SnCs) plays a causative role in many age-related diseases and has also been implicated in the pathogenesis and progression of metabolic dysfunction-associated steatotic liver disease (MASLD). Senolytics that can selectively kill SnCs have the potential to be developed as therapeutics for these diseases. Here we report the finding that 753b, a dual BCL-xL/BCL-2 proteolysis-targeting chimera (PROTAC), acts as a potent and liver-tropic senolytic. We found that treatment with 753b selectively reduced SnCs in the liver in aged mice and STAM mice in part due to its sequestration in the liver. Moreover, 753b treatment could effectively reduce the progression of MASLD and the development of hepatocellular carcinoma (HCC) in STAM mice even after the mice developed substantial metabolic dysfunction-associated steatohepatitis (MASH) and hepatic fibrosis. These findings suggest that BCL-xL/BCL-2 PROTACs have the potential to be developed as therapeutics for MASLD to reduce MASH-driven HCC.

Chronic Lymphocytic Leukemia: 2025 Update on the Epidemiology, Pathogenesis, Diagnosis, and Therapy

DISEASE OVERVIEW

Chronic lymphocytic leukemia (CLL) is the most frequent type of leukemia. It typically occurs in older patients and has a highly variable clinical course. Leukemic transformation is initiated by specific genomic alterations that interfere with the regulation of proliferation and apoptosis in clonal B-cells.

DIAGNOSIS

The diagnosis is established by blood counts, blood smears, and immunophenotyping of circulating B-lymphocytes, which identify a clonal B-cell population carrying the CD5 antigen as well as typical B-cell markers.

PROGNOSIS AND STAGING

Two clinical staging systems, Rai and Binet, provide prognostic information by using the results of physical examination and blood counts. Various biological and genetic markers provide additional prognostic information. Deletions of the short arm of chromosome 17 (del(17p)) and/or mutations of the TP53 gene predict a shorter time to progression with most targeted therapies. The CLL international prognostic index (CLL-IPI) integrates genetic, biological, and clinical variables to identify distinct risk groups of patients with CLL. The CLL-IPI retains its significance in the era of targeted agents, but the overall prognosis of CLL patients with high-risk stages has improved.

THERAPY

Only patients with active or symptomatic disease or with advanced Binet or Rai stages require therapy. When treatment is indicated, several therapeutic options exist: combinations of the BCL2 inhibitor venetoclax with obinutuzumab, or venetoclax with ibrutinib, or monotherapy with one of the inhibitors of Bruton tyrosine kinase (BTK). At relapse, the initial treatment may be repeated if the treatment-free interval exceeds 3 years. If the leukemia relapses earlier, therapy should be changed using an alternative regimen.

FUTURE CHALLENGES

Combinations of targeted agents now provide efficient therapies with a fixed duration that generate deep and durable remissions. These fixed-duration therapies have gained territory in the management of CLL, as they are cost-effective, avoid the emergence of resistance, and offer treatment free time to the patient. The cure rate of these novel combination regimens is unknown. Moreover, the optimal sequencing of targeted therapies remains to be determined. A medical challenge is to treat patients who are double-refractory to both BTK and BCL2 inhibitors. These patients need to be treated within experimental protocols using novel drugs.

Comparative efficacy of venetoclax-based regiments in the management of chronic lymphocytic leukemia: a systematic review and metanalysis

Chronic lymphocytic leukemia and small lymphocytic lymphoma (CLL/SLL) are common lymphoproliferative diseases in the elderly, accounting for 33% of all leukemias. The use of targeted therapies has significantly changed the management landscape of CLL/SLL. However, the efficacy of specific targeted therapies, such as venetoclax-based therapies, is limited. This review, therefore, aims to summarize the current evidence on the effectiveness and safety of venetoclax-based treatments in the management of CLL/SLL. We conducted a comprehensive search of three electronic databases, PubMed, Science Direct and Google Scholar, for all relevant articles. The reported outcomes were then analyzed using the statistical software Review Manager (RevMan 5.4.1). Our electronic search yielded 347 articles, of which only five were included in the review. We pooled the outcomes from 2195 patients. Our analysis found that venetoclax-based therapies significantly increased progression-free survival (PFS) (HR 0.30; 95% CI [0.21, 0.43] p < 0.00001), overall survival (OS) (HR 0.60; 95% CI [0.45, 0.80] p = 0.0004), and time to the next treatment (TTNT) (HR 0.29; 95% [0.18, 0.46] p < 0.00001). Additionally, we found the comparative safety of venetoclax-based therapies to other combination therapies. Our study found that venetoclax-based therapies are superior to other combination therapies in prolonging survival. Furthermore, they are comparable in safety to standard chemotherapy regimens and cost-effective. The findings of this review provide preliminary evidence on the efficacy of venetoclax-based regimens in CLL/SLL. However, further research is required to determine the best comparative regimen and the feasibility of venetoclax monotherapy in patients with CLL/SLL.

Semi-mechanistic population PK/PD model to aid clinical understanding of myelodysplastic syndromes following treatment with Venetoclax and Azacitidine

Myelodysplastic syndromes (MDS) represent a group of bone marrow disorders involving cytopenias, hypercellular bone marrow, and dysplastic hematopoietic progenitors. MDS remains a challenge to treat due to the complex interplay between disease-induced and treatment-related cytopenias. Venetoclax, a selective BCL-2 inhibitor, in combination with azacitidine, a hypomethylating agent, is currently being investigated in patients with previously untreated higher-risk MDS. We present an integrated semi-mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model developed using preliminary clinical data from an ongoing Phase 1b study evaluating the safety and efficacy of venetoclax in combination with azacitidine in treatment-naïve patients with higher-risk MDS. Longitudinal data from 57 patients were used to develop the model, which accounted for venetoclax PK and azacitidine treatment to describe time dynamics of bone marrow blasts, neutrophils, red blood cells, and platelets. The proliferation and maturation of progenitor cells in the bone marrow to peripheral cells is described via three parallel connected transit models including feedback terms. The model also accounted for bone marrow crowding and its impact on hematopoiesis. Model validation demonstrated adequate goodness-of-fit, visual and numerical predictive checks. Model predicted complete remission (CR) rates and marrow complete remission (mCR) rates closely matched observed rates in the clinical study, and simulated efficacy (recovery of blast count, CR, and mCR rates) and safety (neutropenia and thrombocytopenia) endpoints aligned with expected outcomes from various dosing regimens. Importantly, the semi-mechanistic model may aid understanding and discriminating between disease-driven and drug-induced cytopenias.