Preclinical evaluation of combination nemtabrutinib and venetoclax in chronic lymphocytic leukemia.

Inhibitors of B cell receptor (BCR) signaling such as the Bruton's tyrosine kinase (BTK) inhibitors are effective therapeutics for chronic lymphocytic leukemia (CLL). The first-in-class covalent BTK inhibitor, ibrutinib, produces durable responses in most CLL patients; however, complete responses are only observed in a minority of patients. B cell lymphoma 2 (BCL2), an anti-apoptotic protein that contributes to CLL cell survival, has also been investigated as a therapeutic target. The BCL2 inhibitor venetoclax is effective in patients with CLL and can produce undetectable minimal residual disease, allowing discontinuation of therapy. In combination, ibrutinib and venetoclax have shown preclinical synergy and clinical efficacy. Nemtabrutinib is a next generation, reversible inhibitor of BTK that potently inhibits BCR signaling in treatment-naïve and ibrutinib-refractory CLL cells ex vivo. The clinical efficacy of combining BTK inhibitors with BCL2 inhibitors motivated us to evaluate the novel combination of nemtabrutinib and venetoclax. In vitro studies show that nemtabrutinib and venetoclax are not antagonistic to each other. In an adoptive transfer CLL mouse model, mice treated with nemtabrutinib and venetoclax had prolonged survival compared to mice treated with ibrutinib and venetoclax. Our preclinical studies further validate the combination of BTK inhibitors with venetoclax and justify further investigation of combining nemtabrutinib with venetoclax in CLL.

Both BRCA1-wild type and -mutant triple-negative breast cancers show sensitivity to the NAE inhibitor MLN4924 which is enhanced upon MLN4924 and cisplatin combination treatment.

Triple-negative breast cancer (TNBC) shows limited therapeutic efficacy. PARP inhibitor has been approved to treat advanced BRCA-mutant breast cancer but shows high resistance. Therefore, the development of new therapeutics that sensitize TNBC irrespective of BRCA status is urgently needed. The neddylation pathway plays a critical role in many physiological processes by regulating the degradation of proteins. MLN4924, a selective inhibitor of the key neddylation enzyme NEDD8 Activation Enzyme (NAE1), shows higher sensitivity to both BRCA1-wild type and -mutant TNBCs compared to other breast cancer subtypes. MLN4924 induced re-replication with >4N DNA content leading to robust DNA damage. Accumulation of unrepaired DNA damage resulted in S and G2/M arrest causing apoptosis and senescence, due to the stabilization of the replication initiation protein CDT1 and the accumulation of cell cycle proteins upon MLN4924 treatment. Moreover, adding MLN4924 to the standard TNBC chemotherapeutic agent cisplatin increased the DNA damage level, further enhancing the sensitivity. In vivo, MLN4924 reduced tumor growth in a NOD-SCID mouse xenograft model by inducing DNA damage which was further augmented with the MLN4924 and cisplatin cotreatment. NAE1 is overexpressed in TNBC cell lines and in patients compared to other breast cancer subtypes suggesting that NAE1 status is prognostic of MLN4924 treatment response and outcome. Taken together, we demonstrated the mechanism of TNBC sensitization by the MLN4924 and MLN4924/cisplatin treatments irrespective of BRCA1 status, provided a strong justification for using MLN4924 alone or in combination with cisplatin, and identified a genetic background in which this combination will be particularly effective.

Notch3-dependent ß-catenin signaling mediates EGFR TKI drug persistence in EGFR mutant NSCLC.

EGFR tyrosine kinase inhibitors cause dramatic responses in EGFR-mutant lung cancer, but resistance universally develops. The involvement of ß-catenin in EGFR TKI resistance has been previously reported, however, the precise mechanism by which ß-catenin activation contributes to EGFR TKI resistance is not clear. Here, we show that EGFR inhibition results in the activation of ß-catenin signaling in a Notch3-dependent manner, which facilitates the survival of a subset of cells that we call "adaptive persisters". We previously reported that EGFR-TKI treatment rapidly activates Notch3, and here we describe the physical association of Notch3 with ß-catenin, leading to increased stability and activation of ß-catenin. We demonstrate that the combination of EGFR-TKI and a ß-catenin inhibitor inhibits the development of these adaptive persisters, decreases tumor burden, improves recurrence free survival, and overall survival in xenograft models. These results supports combined EGFR-TKI and ß-catenin inhibition in patients with EGFR mutant lung cancer.

A comprehensive study on dehydration-induced antioxidative responses during germination of Indian bread wheat (Triticum aestivum L. em Thell) cultivars collected from different agroclimatic zones.

To explore the adaptability of bread wheat to dehydration stress, we screened 28 cultivars collected from different agroclimatic zones, on the basis of malonaldehyde content as biochemical marker in roots of wheat seedlings during germination and classified them as highly tolerant, tolerant, sensitive and highly sensitive. From this primary screening, ten cultivars that showed differential responses to dehydration stress were selected to understand the biochemical and physiological basis of stress tolerance mechanisms. The highly tolerant cultivars showed lower levels of lipid peroxidation, less membrane damage, increased levels of antioxidants, enzymes like catalase, ascorbate peroxidase, glutathione reductase activities, and maintained higher relative water content in comparison to sensitive cultivars, indicating better protection mechanism operating in tolerant cultivars. Correspondingly, highly tolerant cultivars exhibited more accumulation of proline and less H2O2 content across different time points of polyethylene glycol treatments in comparison to sensitive ones. The above biochemical and physiological parameters were further validated through northern analysis of catalase (CAT1) gene, that showed differential expression patterns in tolerant and sensitive cultivars largely in confirmation with the biochemical and physiological analyses. Our study positively correlates the differences in the redox status and antioxidant defense system between tolerant and sensitive cultivars for the establishment of wheat seedlings in typical dehydration conditions.

Inhibition of lindane-induced toxicity using alpha-lipoic acid and vitamin E in the brain of Mus musculus.

In the present investigation, we have used adenosine triphosphatase (ATPase) activity as biochemical test of toxic action of lindane that was explained by lipid peroxidation model. Study was also undertaken to ascertain the potential protective role of alpha-lipoic acid (ALA) and vitamin E on the same parameters. Highly acute dose of lindane, i.e., 40 mg/kg bw for 18 h exposure, was used for creating lesions in brain. Lipid peroxidation was measured in terms of glutathione peroxidase and thio barbituric acid-reacting substances (TBARS). Various brain regions under investigation were cerebellum and pons-medulla oblongata. Healthy, male, Swiss mice (7-8 weeks old) were allocated into four groups. First group was control, second group was treated with lindane, third group was treated purely with antioxidants, and fourth group received both antioxidants and lindane treatment. Results revealed the significant difference (at 1% and 5% in all groups) in all studied parameters from control. Increased TBARS level in second group suggests that lindane enhances the production of free radicals in studied brain regions. Antioxidants under test are efficient remedy for neurotoxicity caused by lindane. We conclude that lindane manifests toxic effects on brain ATPase and enhances lipid peroxidation. ALA and vitamin E in combination may provide protection against lindane-induced acute toxicity.