Project description:Pancreatic ductal adenocarcinoma(PDAC) is a highly lethal malignancy with poor response rate to therapy. An immune suppressive tumor microenvironment (TME) and oncogenic mutations in KRAS have been implicated as drivers of resistance to both conventional and immune therapies. As such, targeting RAS/MAPK signaling is an attractive strategy. However, in practice, MAPK inhibition has not yet shown clinical efficacy, likely due to rapid acquisition resistance in PDAC cells. Tumor intrinsic mechanisms of resistance to RAS/MAPK have been studied, however, the unique PDAC TME may also be a key driver in resistance. Previous studies have shown that FAK inhibition can reprogram the PDAC TME and delay PDAC progression in animal models. Herein, we found that long-term FAK inhibitor treatment leads to hyperactivation of the MAPK pathway in both genetically engineered mouse models and in post-treatment PDAC tissues from FAK inhibitor clinical trials. Concomitant inhibition of both FAK (VS4718) and RAF/MEK (V6766) signaling dramatically suppressed tumor cell growth, leading to increased survival across multiple PDAC mouse models. The mechanisms of synergy include both changes in tumor-intrinsic signaling and modulation of tumor/stroma interactions that drive MEK resistance. In the TME, we found that cancer associated fibroblasts (CAFs) can impair the downregulation of cMyc by MEK inhibition in PDAC cells. This results in de-novo resistance to MEK inhibition in fibrotic conditions. By contrast, FAK inhibitors reprogram CAFs to suppress the production of key growth factors, including FGF1, that drives resistance to RAF/MEK inhibition. While combined FAK and RAF/MEK inhibition only leads to disease stasis, the addition of chemotherapy to the combination led to tumor regression and improved long-term survival in PDAC mouse models. Analysis of tumor immunity showed that the combination of FAK and MEK inhibition improved anti-tumor immunity and improved priming of T cell responses, which was further improved with the addition of chemotherapy. These findings led to testing of FAK (Defactinib) plus RAF/MEK (Avutometinib) inhibition in combination with gemcitabine and nab-paclitaxel in advanced pancreatic cancer patients (NCT05669482). Finally, we tested if the addition of immunotherapy could enhance the efficacy of the FAKi/MEKi/chemotherapy and found adding in either PD1 or CTLA4/PD1 blockade led to long term disease control in PDAC animal models. Together, these studies identified novel FAK inhibition as a route to overcome both tumor intrinsic and stromal-derived resistance to MAPK inhibition and showed that this combination can be exploited to increase the efficacy of cytotoxic and immunotherapy approaches.

Project description:Purpose: Focal adhesion kinase (FAK), hyaluronan (HA), and hyaluronan synthase-3 (HAS3) have been implicated in cancer growth and progression. FAK inhibition with the small molecule inhibitor Y15 decreases colon cancer cell growth in vitro and in vivo. HAS3 inhibition in colon cancer cells decreases FAK expression and activation, and exogenous HA increases FAK activation. We sought to determine the genes affected by HAS and FAK inhibition and hypothesized that dual inhibition would synergistically inhibit viability. Methods: We treated SW620 colon cancer cells with Y15 to inhibit FAK. We used two strategies to inhibit HAS: (1) cells were transfected with siRNA (HAS3 inhibited); a scrambled sequence was used as a control (HAS3 scrambled), and (2) cells were treated with the HAS inhibitor 4-methylumbelliferone (4-MU). To determine the effect on viability, MTT assays were performed on transfected cells treated with Y15, and wild type cells treated with Y15 alone, 4-MU alone or Y15+4-MU. Treated and untreated cells were submitted to the gene microarray facility for expression profiling. RT-PCR was done to confirm the results. Results: HAS and FAK inhibition affected cell viability. Y15 and 4-MU decreased viability in a dose-dependent manner; viability was further inhibited by treatment with Y15+4-MU in combination (p<0.05). HAS-inhibited cells treated with as little as 2 M of Y15 showed significantly decreased viability compared to HAS scrambled cells treated with the same dose (p<0.05), suggesting synergistic inhibition of viability with dual FAK/HAS inhibition. Microarray analysis showed more than 2-fold up- or down-regulation of 121 genes by HAS inhibition, and 696 genes by FAK inhibition (p<0.05). Of 29 genes that were common to both groups, 9 were down-regulated (CBS, DHRS3, EEPD1, ESPN, FAM46C, GRTP1, IL20RA, INHBE, SCNN1A) and 4 were up-regulated (ANXA1, MALL, RGS2, SNAI2). RT-PCR confirmed these findings. Among the genes affected by FAK or HAS3 inhibition were FOX genes (apoptosis, cell cycle regulation), ANXA1 (apoptosis, proliferation), IL8 (cell cycle regulation, adhesion, proliferation), RGS2 (cell cycle regulation), CEACAM6 (adhesion), SNAI2 (transcription regulation), and SFRP5 (apoptosis). Several genes were specific to either FAK or HAS3 inhibition and several were common to both. Gene expression profiles of samples isolated from human colorectal cancer cells (SW620). A comparison of gene expression between untreated cells and cells treated with 4mcM of Y15. A second comparison between cells transfected with siRNA to HAS3 (HAS3-silenced) and cells transfected with a scrambled control sequence (sc). Two replicates each.

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Elucidation of focal adhesion kinase as a modulator of migration and invasion and as a potential therapeutic target in chronic lymphocytic leukemia (RNA-Seq II)

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