MIK665

BH3 mimetics, including the BCL2/BCLXL/BCLw inhibitor navitoclax and MCL1 inhibitors S64315 and tapotoclax, have undergone clinical testing for a variety of neoplasms...Building on the observation that BH3 mimetic monotherapy induces AMP kinase (AMPK) activation in multiple acute leukemia cell lines, we report that the AMPK inhibitors (AMPKis) dorsomorphin and BAY-3827 sensitize these cells to navitoclax or MCL1 inhibitors...Conversely, dorsomorphin synergizes with navitoclax or the MCL1 inhibitor S63845 to induce cell death in primary acute leukemia samples ex vivo and increases the antitumor effects of navitoclax or S63845 in several xenograft models in vivo with little or no increase in toxicity in normal tissues. These results suggest that AMPK inhibition can sensitize acute leukemia to multiple BH3 mimetics, potentially allowing administration of lower doses while inducing similar antineoplastic effects.

In this study, we show that the MCL1 inhibitor S64315 reduces melanoma tumor growth in an immune cell-dependent manner in mice...Together, this proof-of-concept study demonstrates the potential of combining an MCL1 inhibitor with anti-PD-1 in the treatment of melanoma. It justifies the further development of next generation MCL1 inhibitors to improve efficacy of ICIs in treating malignant melanoma.

P1, N=37, Active, not recruiting, Novartis Pharmaceuticals | Trial primary completion date: Dec 2023 --> Jun 2024

This combination also prolonged overall survival compared with using S64315 or venetoclax alone. Our research highlights the therapeutic potential of inhibiting Mcl-1 and Bcl-2 simultaneously in chemoresistant cancers and provides a rationale for initiating clinical trials to investigate the combination of S64315 and venetoclax for the treatment of advanced colon and cervical cancer.

P1, N=37, Active, not recruiting, Novartis Pharmaceuticals | Trial completion date: Dec 2023 --> Apr 2024

Therefore, we analyzed the efficacy of the two BH3-mimetics ABT-199 (Bcl-2 inhibitor) and MIK665 (Mcl-1 inhibitor) in HCC cell lines with differential expression levels of endogenous Bcl-2 and Mcl-1. Both drugs acted synergistically, highlighting the effectivity of this specific BH3-mimetic combination, particularly in HCC cell lines. These results indicate the potential of combining inhibitors of the BCL-2 family as new therapeutic options in HCC.

P1, N=37, Active, not recruiting, Novartis Pharmaceuticals | Trial completion date: Sep 2024 --> Dec 2023 | Trial primary completion date: Sep 2024 --> Dec 2023

Despite being previously considered undruggable, seven small-molecule Mcl-1 inhibitors have recently entered clinical trials. Here, we report the crystal structure of the clinical-stage inhibitor AMG-176 bound to Mcl-1 and analyze its interaction along with clinical inhibitors AZD5991 and S64315...Nuclear Magnetic Resonance (NMR)-based free ligand conformer analysis demonstrates that such unprecedented induced fit is uniquely achieved by designing highly rigid inhibitors, preorganized in their bioactive conformation. By elucidating key chemistry design principles, this work provides a roadmap for targeting the largely untapped PPI class more successfully.

The challenge is the observed resistance to venetoclax, for which the MCL-1 protein may be largely responsible. Molecules with the potential to break the associated resistance include S63845, S64315, chidamide and arsenic trioxide (ATO)...Knockdown of the PD-L1 gene in preclinical studies was associated with increased levels of BCL-2 and MCL-1 in lymphocytes T, which could increase their survival and promote tumor apoptosis. A trial (NCT03969446) is currently underway to combine inhibitors from both groups.

In summary, our study identified a highly synergistic drug combination, venetoclax and dinaciclib, for the treatment of hypodiploid B ALL, an aggressive leukemia with few effective current therapies. Finally, the promising results presented in this study may prompt further studies to support the inclusion of hypodiploid and other B-ALL patients to clinical trials combining phase I/II drugs against BCL-2 (mainly venetoclax) and CDK9 (dinaciclib, alvocidib, flavopiridol, SNS-032) or MCL-1 (MIK-665).

The human HCC cell lines HepG2, Hep3B and Huh7 were treated with 0,01 - 5 μM ABT-199 and 0,01 - 6 μM MIK665 either alone or in combination. HCC is one of the most common cancer types and the third leading cause of cancer related deaths worldwide. Although screening and therapy have improved over the past years, overall prognosis remains poor. Therefore, new therapeutic options are urgently needed.

Synthetic inhibitors targeting these proteins have been developed, and some hematological malignancies are now widely treated with a BCL-2 inhibitor (venetoclax)...Six MCL-1 inhibitors (S64315, AZD-5991, AMG-176, AMG-397, ABBV-467 and PRT1419) have been evaluated in clinical trials since 2016, but some were affected by safety issues and none are currently used clinically...Importantly, a similar treatment with NA1-115-7 was not toxic to erythrocytes, peripheral blood mononuclear cells, platelets, or cardiomyocytes. These results highlight the potential of natural products for use as specific BH3 mimetics non-toxic to normal cells, and they suggest that NA1-115-7 may be a promising tool for use in cancer treatment.

BH3-mimetics directly target resistance to apoptosis as one of the hallmarks of cancer. They have already proven beneficial in hematologic and some solid cancers. We now provide evidence that a combination of the BH3-mimetics ABT-199 and MIK665 effectively induces cell death in HCC cell lines.

Methods Primary leukemic blasts from APL mice (n=4) and patients (age, 25-52y; n=10) were treated with VEN (250-500nM), ATO, ATRA (1µM), and S64315 (10-50nM) monotherapies and combinations and evaluated for cell survival. Finally, in vivo CLDX model revealed limited effect of VEN and S64315 monotherapy, while the combination was able to effectively reduce the leukemic burden, resulting in increased overall survival (vehicle:15 vs Combo:42 days). Conclusion The combination of BCL2 and MCL1 inhibition is a potential effective treatment in ATO/RA resistant APL patients and could be clinically explored in this category of patients with very poor prognosis.

We have recently shown for the first time that a novel MCL-1 inhibitor S63845 elicited synergistic activity with FLT3 inhibitors AC220, sorafenib and with a multi-kinase inhibitor midostaurin at nanomolar doses in pre-clinical in vitro models of FLT3-ITD AML, including cells resistant to venetoclax ( Skwarska A, et al...Mice were treated for 3 weeks with low doses of midostaurin (25 mg/kg/5 days per week) and with MIK665, structurally optimized version of S63845 Mcl-1 inhibitor with improved pharmacokinetics in mice ( Halilovic E, et al...The long-term effect of combination on mice survival is currently being tested and will be reported. Altogether, our results indicate that efficacy of FLT3-ITD inhibitors can be enhanced through combination with low doses BH3 mimetics targeting MCL-1 and provide a rationale for the clinical evaluation of such combinations in FLT3 mutant AML patients.

Importantly, the venetoclax/S63845 combination induced tumor regressions in SS patient-derived xenograft (PDX) models. As a very close analog of S63845 (S64315) is now in clinical trials with venetoclax in AML (NCT03672695), the combination of MCL-1 BH3 mimetics and venetoclax should be considered for SS patients as a new therapy.

Both, the very similar Mcl-1 inhibitor MIK665 (S64315) and the JAK1/2 inhibitor ruxolitinib are currently in early clinical evaluation in patients with advanced multiple myeloma. The data presented here suggest that a combination of ruxolitinib and the Mcl-1 inhibitor S63845 is particularly efficient in control of multiple myeloma.

Strong and persistent tumor regression in xenograft models of lymphoid malignancies in mouse and rat were observed at well tolerated doses following weekly IV administration of S65487 in combination with the MCL-1-specific inhibitor, S64315/MIK665. Altogether, these data demonstrate that S65487/VOB560 has significant therapeutic potential against human lymphoid and myeloid malignancies as well as in patients with Venetoclax resistant leukemias. Clinical studies are currently ongoing with S65487/VOB560 (NCT03755154).

In hematological cancers, venetoclax (BCL2 inhibitor) is approved and S64315 (MCL1 inhibitor/MCL1i) is in clinical trials. However, MCL1i alone was ineffective at killing the UM stem-like cells, but a combination with venetoclax synergistically killed UM stem-like cells, inhibited their capacity to self-renew, and reduced tumor growth in vivo (p<0.01). In summary, our data indicated MCL1i, alone or in combination with venetoclax, are promising treatments for UM.

During optimization, we have also established predictive PD markers of Mcl-1 inhibition and achieved both efficient in vitro cell killing and tumor regression in Mcl-1 dependent cancer models. The preclinical candidate has drug-like properties that have enabled its development and entry into clinical trials.

We explored the efficacy of combining two BH3 mimetics, ABT-199 and a myeloid cell leukemia sequence 1 (MCL1) inhibitor (S63845 or S64315/MIK665) in cutaneous, mucosal and acral melanomas, in vitro and in vivo. Our knockdown/knockout experiments suggest that several pro-apoptotic BCL2 family members, BCL2-like 11 (apoptosis facilitator) (BIM), phorbol-12-myristate-13-acetate-induced protein 1 (NOXA) or BID, play a role in the combination-induced effects. Overall, our study supports the rationale for combining an MCL1 inhibitor with a BCL2 inhibitor as a therapeutic option in patients with advanced melanoma.

Moreover, in mouse xenograft model, the combination inhibited tumor growth of multiple melanomas (p <0.01), had tolerable toxicity, and reduced sphere forming capacity (p < 0.05) in a downstream in vitro assay. In summary, this study suggests that dual targeting of MCL1 and BCLXL can be an alternative treatment for melanoma patients who have exhausted current treatment options.

The obtained compounds described here exhibit nanomolar binding affinity and mechanism-based cellular efficacy, caspase induction, and growth inhibition. These early research efforts illustrate drug discovery optimization from thienopyrimidine hits to a lead compound, the chemical series leading to the identification of our more advanced compounds S63845 and S64315.

Recapitulated in our mouse xenograft model, the combination inhibited tumor growth, reduced sphere-forming capacity (p  0.40). Taken together, this study suggests that dual targeting of MCL1 and BCLXL should be considered as a treatment option for difficult-to-treat melanoma patients.