BCL2 mutation

P1, N=45, Recruiting, National Cancer Institute (NCI) | Not yet recruiting --> Recruiting | Initiation date: Oct 2024 --> Jul 2025

The approval of venetoclax, a B-cell lymphoma-2 (Bcl-2) selective inhibitor, for the treatment of chronic lymphocytic leukemia demonstrated that the antiapoptotic protein Bcl-2 is a druggable target for B-cell malignancies. Comprehensive structure optimization led to the clinical candidate BGB-11417 (compound 12e, sonrotoclax), which exhibits strong in vitro and in vivo inhibitory activity against both WT Bcl-2 and the G101V mutant, as well as excellent selectivity over Bcl-xL without obvious cytochrome P450 inhibition. Currently, BGB-11417 is undergoing phase II/III clinical assessments as monotherapy and combination treatment.

In contrast, relapsed CLL that arises while being off therapy after a period of time-limited venetoclax-based regimens maintains sensitivity to re-treatment with venetoclax for the majority of patients. Novel strategies related to therapeutic targeting of apoptosis include next-generation BCL-2 inhibitors with improved potency and pharmacokinetic profiles, direct targeting of anti-apoptotic BH3 family proteins beyond BCL-2 such as MCL-1, and indirect targeting of MCL-1 through mechanisms such as small molecule cyclin-dependent kinase 9 inhibitors.

Leukemia drug venetoclax is currently the only approved selective BCL-2 inhibitor...Furthermore, we identify a single-residue discrepancy between BCL-2 D111 and BCL-XL A104 as a molecular "switch" that can differently engage CPs. Our study suggests that CPs may inhibit BCL-2 or BCL-XL by delicately modulating protein-protein interactions, potentially benefiting the development of next-generation therapeutics.

In summary, sonrotoclax emerges as a potential second-generation BCL2 inhibitor for the treatment of hematologic malignancies with the potential to overcome BCL2 mutation-induced venetoclax resistance. Sonrotoclax is currently under investigation in multiple clinical trials.

However, with resistant patients' subsets targeted combination therapies are becoming an increasingly attractive option. We explore the incorporation of non-BCL-2 inhibitors, next-generation BCL-2 and multi-protein agents, other inhibitors most prominently FLT-3 inhibitors in addition to Venetoclax, and other novel approaches for resolving Venetoclax resistance.

Additionally, we provide evidence that anti-apoptotic BCL-2 family protein phosphorylation alters the apoptotic protein interactome, thereby changing the profile of functional dependence on these pro-survival proteins. Targeting BCL-2 family protein phosphorylation with phosphatase-activating drugs re-wired these dependences, thus restoring sensitivity to venetoclax in a panel of venetoclax resistant lymphoid cell lines, resistant mouse model, and paired patient samples pre-venetoclax and at time of progression.

P3, N=20, Completed, Mayo Clinic | Active, not recruiting --> Completed | Trial completion date: Jan 2026 --> Nov 2023

5 pts have started subsequent therapy (acalabrutinib, n=4; ibrutinib, n=1; all are clinically responding); 1 pt has not yet started therapy. We report long term follow-up of combined IBR and VEN in first-line CLL (n=120) with a 5-year PFS of 90.1%. The 5-year PFS for pts with del(17p)/TP53 mutation is 86.1%. Retreatment with BTK inhibitor appears effective for pts with disease relapse.

Older cHL patients exhibit unique genomic characteristics compared to younger counterparts, including more prevalent H2 tumor genetic subtype and EBV positivity. Identifying of a high-risk subgroup of older cHL underscores the importance of ctDNA levels and EBV status. We envision future trials of personalized biomarker driven treatment strategies could therapeutically target this risk, including by PD1 blockade.

Venetoclax is a specific inhibitor of Bcl-2, the key protein which protects CLL cells from intrinsic apoptosis, whereas the Bruton's Tyrosine Kinase (BTK) inhibitor ibrutinib kills CLL cells via blockade of B-cell receptor (BCR) signalling. In conclusion, WH25244 is a PROTAC-based Bcl-2/Bcl-xL degrader with the potential to overcome venetoclax-resistant CLL dependent on Bcl-xL and mutant Bcl-2. Relative to its precursor, navitoclax, it shows increased potency against CLL cells and decreased toxicity against platelets in vitro, due to its VHL-dependent activity and minimal expression of VHL in platelets.

In conclusion, our results provide a high-resolution view of events spanning FL progression and indicate a major role of early TME remodeling in establishing a suitable niche for progression. Early intervention aimed to target the B cell-tumor microenvironment interactions driving intra-tumoral heterogeneity may represent a promising therapeutic avenue against early disease and prevention of FL recurrence.

Fixed Duration of Venetoclax-Rituximab in Relapsed/Refractory Chronic Lymphocytic Leukemia Eradicates Minimal Residual Disease and Prolongs Survival: Post-Treatment Follow-Up of the MURANO Phase III Study. JCO 2019, 7(4):269-277

BTK Cysteine 481 substitution is known to contribute to cBTKi acquired resistance to ibrutinib, acalabrutinib, and zanubrutinib. Despite this cohort representing the first relapsing CLL patients from BRUIN and presenting with frequent baseline BTK mutations, response to pirtobrutinib was high, with an ORR of 83%, and substantial clearance of BTK C481 clones. At progression, the majority of pts (56%) either acquired non-BTK mutations or did not acquire any resistance mutations in this targeted panel, suggesting alternative resistance mechanisms. A smaller group of patients (44%) displayed emergence of non-C481 clones, particularly gatekeeper T474 and kinase-impaired L528W mutations.

To evaluate if combination treatment of AZD0466 with BTK inhibitors would improve efficacy, we transplanted murine Eµ-TCL1 tumors into syngeneic recipient mice and randomized them for treatment with vehicle, ibrutinib (30mg/kg in drinking water), acalabrutinib (25mg/kg, p.o. QD), AZD0466 (70mg/kg, i.v., QW) and combination of AZD0466 with ibrutinib or acalabrutinib. Moreover, AZD4320 was highly efficacious in MAVER-1 and MINO cell line models where resistance to venetoclax mediated by BCL-XL upregulation was modelled by an in vitro dose escalation method. In summary, our pre-clinical study shows that the dual BCL2/BCL-XL inhibitor could represent an important treatment option for venetoclax resistance mediated by specific BCL2 mutations or BCL-XL upregulation and that its efficacy could be further improved upon combination treatment with BTKi.

The Bellini study demonstrated that combination therapy of BH3-mimetic venetoclax with velcade improves progression-free survival (PFS) and response rates in this subgroup of MM patients...Simultaneous inhibition of MCL1 (via S63845) or BCL-XL (via A155463) and BCL2 (via venetoclax) increased BIM release and enhanced cell death in the resistant clones compared to single agents, with combination index (CI) values < 0.3 in all doses tested. In conclusion, we report that resistance to Venetoclax in in vitro models of MM evolves from the outgrowth of persister clones with a shift in mitochondrial dependency that confers broad resistance to all anti-tumor agents, including standard-of-care myeloma drugs.

Both lacked mutations involving IRF4 and NF-kB pathway genes that are frequently detected in large B-cell lymphoma with IRF4 rearrangement, and one case showed DLBCL-EZH2 type mutations, including KMT2D and BCL2 mutations, similar to 2 previously reported DLBCL with BCL2 and IRF4 rearrangements. Adults with FL and FL/DLBCL with BCL2 and IRF4 rearrangements display clinicopathologic and mutational features more akin to FL and DLBCL and should not be characterized as large B-cell lymphoma with IRF4 rearrangement.

With regard to treatment, 56% received Brutone tyrosine kinase (BTK) inhibitors, others received Bcl-2 inhibitor venetoclax (31%) or PI3K inhibitor idelalisib (13%). This interim analysis points to the dynamic and complex nature of genomic alterations in CLL, with implications for disease progression and therapeutic responses. Our findings highlight the importance of longitudinal genomic monitoring to uncover evolving mutational profiles and their clinical implications.

Knowing that BCL-xL inhibition in the clinic has been limited by platelet toxicity, PROTACs PZ18753b and WH25244 were synthesized from navitoclax (BCL-2/BCL-xL dual inhibitor) linked to a VHL E3 ligase ligand to target Bcl-2 and Bcl-xL for degradation, with improved specificity to cancer cells while sparing platelets. PZ18753b and WH25244 have preclinical efficacy in baseline CLL and can degrade, both, Bcl-xL and mutant Bcl-2 proteins, which are known to confer venetoclax resistance. This translational study supports the development of novel therapeutics for the treatment of CLL subgroups with adverse clinical prognosis and will open new frontiers as we better understand the biology of this disease.

Ex vivo drug treatments included: BCL2i (inhibitor): venetoclax; MCL-1i: AZD5991, S63845 and BCLXLi: A133. The genomic landscape of BCL2-R CLL is characterized by a high frequency of trisomy 12, subclonal NOTCH and RAS pathway mutations, as well as BCL2 and MLL2 mutations. Protein expression, BH3 profiling and viability assays data are consistent with nearly exclusive dependence on Bcl-2.

This report highlights the successful use of a venetoclax-based regimen in CLL patients with CNS involvement. It presents a case of primary ibrutinib-resistant CNS involvement in CLL, responding to second-line therapy with venetoclax-rituximab. Additionally, it discusses a case of CNS relapse after venetoclax treatment discontinuation, with a response to resuming venetoclax.

Patients previously treated with B-cell receptor pathway inhibitors (BCRi), such as ibrutinib and idelalisib, have lower response rates to Ven; those who are refractory to prior BCRi have a significantly higher risk of relapse than those who are not refractory [1]. With extended follow-up, Ven demonstrated durable responses in patients with CLL who progressed on BCRi, irrespective of BTK mutation status. BCL-2 resistance mutations were detected in 19.1% (13/68) of patients, generally at low VAF. These acquired mutations were detectable in patients with prolonged Ven exposure, supporting further exploration of strategies focused on time-limited Ven exposure.

Among 97 FL patients who did not initially receive rituximab-containing therapy, nonsynonymous BCL2 mutations at VAF ≥20% were associated with increased transformation risk (HR 3.01, 95% CI 1.04-8.78, p = 0.043) and a trend toward shorter event-free survival (EFS, median 20 months with mutations versus 54 months without, p = 0.052)...Across the entire population, nonsynonymous BCL2 mutations at VAF ≥20% were associated with decreased EFS (HR 1.55, 95% CI 1.02-2.35, p = 0.043 after correction for FLIPI and treatment) and decreased overall survival after median 14-year follow-up (HR 1.82, 95% CI 1.05-3.17, p = 0.034). Thus, high VAF nonsynonymous BCL2 mutations remain prognostic even in the chemoimmunotherapy era.

After the first induction cycle with the 7+3 scheme (cytarabine + idarubicin), refractoriness was observed, in addition to the appearance of 6% of nuclei with BCL2 amplification by FISH, while maintaining the TP53 variant (confirmed by PCR). A new therapeutic scheme was initiated with decitabine 10- venetoclax... Clonal evolution of the leukemia was evidenced by the acquisition of BCL2 amplification alongside changes in the karyotype after antineoplastic treatment, and particularly following venetoclax administration, while maintaining the primary TP53 pathogenic variant.The increasing use of targeted therapies is improving remission and survival rates in most hematologic neoplasms, but it is also leading to the emergence of therapy-related clonal selections, as seen in this case, which could cause resistant relapses or even refractoriness. Understanding the mechanisms responsible for these phenomena would help to understand their relevance in the evolution of these patients.

Four phase-2 trials of the German CLL Study Group evaluated time-limited combination regimens in treatment-naïve or relapsed/refractory CLL: BAG (venetoclax-obinutuzumab), BCG (idelalisib- obinutuzumab), BIG (ibrutinib-obinutuzumab) and BIO (ibrutinib-ofatumumab), with or without initial debulking with bendamustine. Genetic risk factors such as the IGHV mutation status remain significant prognostic factors for PFS in the context of time-limited treatment with targeted drugs. Acquisition of high-risk markers was rare and resistance mutations were only acquired in 2 of 44 cases. Chronic lymphocytic leukemia, ibrutinib, Prognostic factor, Venetoclax

Background: The BCL-2 inhibitor venetoclax, in combination with hypomethylating agents (HMA) or low dose cytarabine, has been introduced to clinical practice as an alternative for AML patients unfit for intensive chemotherapy... We demonstrate that sensitivity to venetoclax and navitoclax correlates with sensitivity to the HDAC inhibitors belinostat, panobinostat and vorinostat in samples from AML patients with relapsed disease (N = 53)...We demonstrated that small doses of HDAC inhibitors, non-toxic as a single agent, can resensitize AML cells to venetoclax and navitoclax by induction of irreversible DNA damage.

P2, N=42, Recruiting, Dana-Farber Cancer Institute | Not yet recruiting --> Recruiting | Initiation date: Aug 2023 --> May 2023

To assess the correlation between disease progression and the most common BCL2 mutations G101V and D103Y, sensitive (10) screening for the most common BCL2 mutations G101V and D103Y was performed in 67 R/R CLL patients during venetoclax single-agent or venetoclax-rituximab combination therapy. This cohort is the largest R/R CLL patient population reported to date in which BCL2 resistance mutations were investigated. Our study demonstrates the feasibility and clinical value of sensitive screening for BCL2 resistance mutations in R/R CLL.

Preferable safety profiles of FCN-683 were shown with no potential hERG inhibitory effect and less drug-drug interaction potential, as evidenced by no inhibitory effect (IC50 >50 μM) on CYP2C9 enzyme compared with VEN (IC50 1.05 μM). Together, FCN-683 is highly potent, selective and highly efficacious against a variety of clinically relevant VEN-resistance BCL-2 mutations in vitro and in vivo and exhibits favorable PK and safety profiles, highlighting its therapeutic potential to become an effective therapeutic approach for VEN-naïve or -resistant BCL-2-addicted B-cell malignancies.

L105 showed great potency on wild type and acquisition resistance mutations of Bcl-2, excellent oral bioavailability, and superior preclinical anti-tumor activities and safety profiles. It may provide new thoughts on treatment for a wide range of Bcl-2-dependent and Venetoclax-resistant hematological cancers.

Mutation status was associated with improvements in PFS in FL pts with mutant BCL2 or mutant EZH2 treated with C+R. iNHL pts with low plasma levels of IL2 levels treated with C+R showed a significant improvement in OS.

P2, N=42, Not yet recruiting, Dana-Farber Cancer Institute

Therefore, we have designed and synthesized dual BCL-2/HDAC inhibitors to target HDAC1, as well as other dual inhibitors to target HDAC6. It is hypothesized that our polypharmacological approach will be comparable with the corresponding polypharmacy approach in cells but superior in vivo; our progress will be presented.

The presence of BCL2 mutations correlates with BCL2 translocations suggesting an AID-induced mechanism. The epitopes recognized by the antibodies are often affected by mutations in that region, therefore may lead to false negative IHC results using the 124/Ventana clone. Given the clinical significance of BCL2 expression in diagnosis and prognostication of FL and DLBCL, it is recommended that alternative antibodies, such as the E17 clone, be used to prevent false negative BCL2 protein expression.

All have previously received a BTKi and 76.5% had also received venetoclax. Double- and emerging triple-refractory CLL (patients who progressed on cBTKi, ncBTKi, and a BCL2 inhibitor) represents a major unmet medical need with no approved therapeutic options and poor survival. These patients may thus benefit from the interruption of BTK kinase-independent scaffolding signaling. In this first-in-human, first-in-class study of a BTK degrader, clinical responses and benefit were observed in heavily pretreated (median 6 prior therapies) patients with CLL who have poor prognostic factors, including those with BTK mutations resistant to cBTKi and ncBTKi, BCL2 mutations and those who were previously treated with both BTKi and BCL2 inhibitors.

In summary, HZ-L105 as a next generation Bcl-2 inhibitor, showed great potency on wild type and acquisition resistance mutations of Bcl-2 in vitro, excellent oral bioavailability, superior anti-tumor activities on preclinical xenograft model, and safety profiles,. It may provide new thoughts on treatment for a wide range of Bcl-2-dependent and Venetoclax-resistant hematological cancers.

To evaluate the prognostic significance of these 4 signatures, we performed signature recovery on two independent FL datasets annotated with mature clinical data (both with OS, one with failure free survival (FFS), which identified heterogeneous survival outcomes between transcriptional subtypes (Figure 1) and highlighted the potential predictive value of the signatures for treatment naïve patients initiating frontline therapy with rituximab and chemotherapy...In summary, our analyses uncovered genetic subtypes of FL with distinct biological and clinical features, providing a potential framework for advancing precision medicine strategies in FL. These results suggest the possibility of using transcriptional signatures and/or their surrogates as novel biomarkers to guide front-line risk-adapted therapy.

In conclusion, we found an association between CREBBP mutations and shorter time to progression in limited-stage FL treated with RT. To our knowledge, this represents a novel genetic prognostic finding in limited-stage FL. Further studies with larger sample sizes are required to confirm the association.

Treatment for chronic lymphocytic leukemia (CLL) is primarily based upon the use of small molecules targeting Bruton's tyrosine kinase (BTK; ibrutinib, acalabrutinib) or BCL-2 (venetoclax)...The efficacy of WH2544 and PZ18753b in treating naïve CLL cells fell in between that of venetoclax and navitoclax...In conclusion, our results suggest that venetoclax refractory CLL cells retain survival dependency on BCL-2 and BCL-xL proteins to evade apoptosis. This vulnerability can be therapeutically exploited using the BCL-2/BCL-xL dual targeting PROTACs PZ18753b and WH2544 in CLL.

Lisaftoclax in combination with alrizomadlin overcomes venetoclax resistance mediated by various mechanisms, including BCL-2 mutations. In addition, we posit further, putative molecular mechanisms. Our data rationalize clinical development of this treatment combination in patients with diseases that are insensitive or resistant to venetoclax.

Mutational status analysis suggests that the pathogenesis of high-grade ChS and progression of diseases may be related to tumor growth and cell proliferation (PI3K-AKT-mTOR, RAS-RAF-MEK-ERK), regulation of cell cycle, and apoptosis (p53 signaling), and chondrocyte differentiation (Hedgehog pathway) signaling pathways. Moreover, methylation of histones may play also an important role in high-grade ChS, but not in the mesenchymal subtype.

Targeted therapies related to oncogenic mutations may be applied based on cfDNA genotyping results. However, the results of this study need to be validated in a larger cohort of FL patients as the analyses conducted in this study have an exploratory nature.