Inhibition of MALT1 and BCL2 Induces Synergistic Antitumor Activity in Models of B-Cell Lymphoma.

The activated B cell (ABC) subset of diffuse large B-cell lymphoma (DLBCL) is characterized by chronic B-cell receptor signaling and associated with poor outcomes when treated with standard therapy. In ABC-DLBCL, MALT1 is a core enzyme that is constitutively activated by stimulation of the B-cell receptor or gain-of-function mutations in upstream components of the signaling pathway, making it an attractive therapeutic target. We discovered a novel small-molecule inhibitor, ABBV-MALT1, that potently shuts down B-cell signaling selectively in ABC-DLBCL preclinical models leading to potent cell growth and xenograft inhibition. We also identified a rational combination partner for ABBV-MALT1 in the BCL2 inhibitor, venetoclax, which when combined significantly synergizes to elicit deep and durable responses in preclinical models. This work highlights the potential of ABBV-MALT1 monotherapy and combination with venetoclax as effective treatment options for patients with ABC-DLBCL.

Functional characterization of a single nucleotide polymorphism associated with Alzheimer's disease in a hiPSC-based neuron model.

Neurodegenerative diseases encompass a group of debilitating conditions resulting from progressive nerve cell death. Of these, Alzheimer's disease (AD) occurs most frequently, but is currently incurable and has limited treatment success. Late onset AD, the most common form, is highly heritable but is caused by a combination of non-genetic risk factors and many low-effect genetic variants whose disease-causing mechanisms remain unclear. By mining the FinnGen study database of phenome-wide association studies, we identified a rare variant, rs148726219, enriched in the Finnish population that is associated with AD risk and dementia, and appears to have arisen on a common haplotype with older AD-associated variants such as rs429358. The rs148726219 variant lies in an overlapping intron of the FosB proto-oncogene (FOSB) and ERCC excision repair 1 (ERCC1) genes. To understand the impact of this SNP on disease phenotypes, we performed CRISPR/Cas9 editing in a human induced pluripotent stem cell (hiPSC) line to generate isogenic clones harboring heterozygous and homozygous alleles of rs148726219. hiPSC clones differentiated into induced excitatory neurons (iNs) did not exhibit detectable molecular or morphological variation in differentiation potential compared to isogenic controls. However, global transcriptome analysis showed differential regulation of nearby genes and upregulation of several biological pathways related to neuronal function, particularly synaptogenesis and calcium signaling, specifically in mature iNs harboring rs148726219 homozygous and heterozygous alleles. Functional differences in iN circuit maturation as measured by calcium imaging were observed across genotypes. Edited mature iNs also displayed downregulation of unfolded protein response and cell death pathways. This study implicates a phenotypic impact of rs148726219 in the context of mature neurons, consistent with its identification in late onset AD, and underscores a hiPSC-based experimental model to functionalize GWAS-identified variants.

Transcriptomics reveals in vivo efficacy of PARP inhibitor combinatorial synergy with platinum-based chemotherapy in human non-small cell lung carcinoma models.

Inhibitors of poly(ADP)-ribose polymerase (PARP) exploit defective DNA repair pathways existing in several forms of cancer, such as those with BRCA mutations, and have proven clinical efficacy as chemosensitizers. However, platinum-based chemopotentiation by PARP inhibitors (PARPi), particularly for non-small cell lung cancer (NSCLC), has only been confirmed in a few preclinical models and the molecular mechanisms that drive PARPi combinatorial synergy with chemotherapeutics remains poorly defined. To better understand these mechanisms, we characterized cisplatin and veliparib efficacy in A549 and Calu6 NSCLC in vivo tumor xenograft models and observed combinatorial synergy in the Calu6 model. Transcriptome-wide analysis of xenografts revealed several differentially expressed genes (DEGs) between untreated and cisplatin + veliparib-treated groups, which were unique from genes identified in either of the single-agent treatment arms. Particularly at 10- and 21-days post-treatment, these DEGs were enriched within pathways involved in DNA damage repair, cell cycle regulation, and senescence. Furthermore, TGF-ß- and integrin-related pathways were enriched in the combination treatment arm, while pathways involved in cholesterol metabolism were identified at earlier time points in both the combination and cisplatin-only groups. These data advance the biological underpinnings of PARPi combined with platinum-based chemotherapy and provides additional insight into the diverse sensitivity of NSCLC models.

Relevance of Platinum-free Interval and BRCA Reversion Mutations for Veliparib Monotherapy after Progression on Carboplatin/Paclitaxel for gBRCA Advanced Breast Cancer (BROCADE3 Crossover).

PURPOSE: Safety, efficacy, and exploratory biomarker analyses were evaluated in patients with advanced HER2-negative germline breast cancer susceptibility gene (gBRCA)-associated breast cancer enrolled in the BROCADE3 trial who received crossover veliparib monotherapy after disease progression on placebo plus carboplatin/paclitaxel. PATIENTS AND METHODS: Eligible patients (N = 513) were randomized 2:1 to veliparib plus carboplatin/paclitaxel or placebo plus carboplatin/paclitaxel; patients had variable platinum-free intervals (PFI) at progression. In the placebo arm, patients were eligible to receive crossover veliparib monotherapy (300-400 mg twice daily continuous). Antitumor activity and adverse events were assessed during crossover veliparib treatment. BRCA reversion mutations at crossover were analyzed retrospectively using next-generation sequencing on plasma circulating tumor DNA (ctDNA). RESULTS: Seventy-five patients in the placebo plus carboplatin/paclitaxel arm received ≥1 dose of crossover veliparib postprogression (mean treatment duration: 154 days). Eight of 50 (16%) patients with measurable disease had a RECIST v1.1 response. Activity was greater in patients with PFI ≥180 days compared with <180 days [responses in 23.1% (3/13) vs. 13.5% (5/37) of patients]. BRCA reversion mutations that restored protein function were detected in ctDNA from 4 of 28 patients tested, and the mean duration of crossover veliparib monotherapy was <1 month in these 4 patients versus 7.49 months in patients lacking reversion mutations. The most frequent adverse events were nausea (61%), vomiting (29%), and fatigue (24%). CONCLUSIONS: Crossover veliparib monotherapy demonstrated limited antitumor activity in patients who experienced disease progression on placebo plus carboplatin/paclitaxel. PFI appeared to affect veliparib activity. BRCA reversion mutations may promote cross-resistance and limit veliparib activity following progression on platinum.

Rapid and efficient conversion of integration-free human induced pluripotent stem cells to GMP-grade culture conditions.

Data suggest that clinical applications of human induced pluripotent stem cells (hiPSCs) will be realized. Nonetheless, clinical applications will require hiPSCs that are free of exogenous DNA and that can be manufactured through Good Manufacturing Practice (GMP). Optimally, derivation of hiPSCs should be rapid and efficient in order to minimize manipulations, reduce potential for accumulation of mutations and minimize financial costs. Previous studies reported the use of modified synthetic mRNAs to reprogram fibroblasts to a pluripotent state. Here, we provide an optimized, fully chemically defined and feeder-free protocol for the derivation of hiPSCs using synthetic mRNAs. The protocol results in derivation of fully reprogrammed hiPSC lines from adult dermal fibroblasts in less than two weeks. The hiPSC lines were successfully tested for their identity, purity, stability and safety at a GMP facility and cryopreserved. To our knowledge, as a proof of principle, these are the first integration-free iPSCs lines that were reproducibly generated through synthetic mRNA reprogramming that could be putatively used for clinical purposes.

Endometrial decidualization: of mice and men.

In murine and human pregnancies, embryos implant by attaching to the luminal epithelium and invading into the stroma of the endometrium. Under the influence of the steroid hormones estrogen and progesterone, the stromal cells surrounding the implanting embryo undergo a remarkable transformation event. This process, known as decidualization, is an essential prerequisite for implantation. It comprises morphogenetic, biochemical, and vascular changes driven by the estrogen and progesterone receptors. The development of mutant mouse models lacking these receptors has firmly established the necessity of steroid signaling for decidualization. Genomic profiling of mouse and human endometrium has uncovered a complex yet highly conserved network of steroid-regulated genes that supports decidualization. To advance our understanding of the mechanisms regulating implantation and better address the clinical challenges of infertility and endometrial diseases such as endometriosis, it is important to integrate the information gained from the mouse and human models.