Immune checkpoint blockade, exemplified by antibodies targeting the PD-1 receptor, can induce durable tumor regressions in some patients. To enhance the efficacy of existing immunotherapies, we screened for small molecules capable of increasing the activity of T cells suppressed by PD-1. Here, we show that short-term exposure to small-molecule inhibitors of cyclin-dependent kinases 4 and 6 (CDK4/6) significantly enhances T-cell activation, contributing to antitumor effects , due in part to the derepression of NFAT family proteins and their target genes, critical regulators of T-cell function. Although CDK4/6 inhibitors decrease T-cell proliferation, they increase tumor infiltration and activation of effector T cells. Moreover, CDK4/6 inhibition augments the response to PD-1 blockade in a novel organotypic tumor spheroid culture system and in multiple murine syngeneic models, thereby providing a rationale for combining CDK4/6 inhibitors and immunotherapies. Our results define previously unrecognized immunomodulatory functions of CDK4/6 and suggest that combining CDK4/6 inhibitors with immune checkpoint blockade may increase treatment efficacy in patients. Furthermore, our study highlights the critical importance of identifying complementary strategies to improve the efficacy of immunotherapy for patients with cancer. .

Hypothesis Proinflammatory cytokine Interleukin (IL)-17A (IL-17A) is overexpressed in a subset of patients with lung cancer. We hypothesized that IL-17A promotes a pro-tumorigenic inflammatory phenotype, and inhibits anti-tumor immune responses. Experimental Design We generated bi-transgenic mice expressing a conditional IL-17A allele along with conditional KrasG12D and performed immune phenotyping of mouse lungs, survival analysis, and treatment studies with antibodies either blocking PD-1 or IL6, or depleting neutrophils. To support preclinical findings, we analyzed human gene expression datasets and immune profiled patient lung tumors. Results Tumors in IL-17:KrasG12D mice grew more rapidly, resulting in a significantly shorter survival as compared to KrasG12D. IL-6, G-CSF, MFG-E8, and CXCL1 were increased in the lungs of IL17:Kras mice. Time course analysis revealed that tumor-associated neutrophils (TANs) were significantly elevated, and lymphocyte recruitment was significantly reduced in IL17:KrasG12D mice as compared to KrasG12D. In therapeutic studies PD-1 blockade was not effective in treating IL-17:KrasG12D tumors. In contrast, blocking IL-6 or depleting neutrophils with an anti-Ly-6G antibody in the IL17:KrasG12D tumors resulted in a clinical response associated with T cell activation. In tumors from lung cancer patients with KRAS mutation we found a correlation among higher levels of IL-17A and the colony stimulating factor (CSF3), and a significant correlation among high neutrophil and lower T cell numbers. Conclusions Here we show that an increase in a single cytokine, IL-17A, without additional mutations, can promote lung cancer growth by promoting inflammation, which contributes to resistance to PD-1 blockade and sensitizes tumors to cytokine/neutrophil depletion.

Purpose KRAS-activating mutations are the most common oncogenic driver in non-small cell lung cancer (NSCLC), but efforts to directly target mutant KRAS have proved a formidable challenge. Therefore, multi-targeted therapy may offer a plausible strategy to effectively treat KRAS-driven NSCLCs. Here, we evaluate the efficacy and mechanistic rationale for combining mTOR and WEE1 inhibition as a potential therapy for lung cancers harboring KRAS mutations. Experimental Design We investigated the synergistic effect of combining mTOR and WEE1 inhibitors on cell viability, apoptosis, and DNA damage repair response using a panel of human KRAS-mutant and wild type NSCLC cell lines and patient-derived xenograft cell lines. Murine autochthonous and human transplant models were used to test the therapeutic efficacy and pharmacodynamic effects of dual treatment. Results We demonstrate that combined inhibition of mTOR and WEE1 induced potent synergistic cytotoxic effects selectively in KRAS-mutant NSCLC cell lines, delayed human tumor xenograft growth and caused tumor regression in a murine lung adenocarcinoma model. Mechanistically, we show that inhibition of mTOR potentiates WEE1 inhibition by abrogating compensatory activation of DNA repair, exacerbating DNA damage in KRAS-mutant NSCLC, and that this effect is due in part to reduction in cyclin D1. Conclusions These findings demonstrate that compromised DNA repair underlies the observed potent synergy of WEE1 and mTOR inhibition and support clinical evaluation of this dual therapy for patients with KRAS-mutant lung cancers.

Background Acute lung injury and respiratory distress syndrome is characterized by uncontrolled inflammation of the lungs after a severe inflammatory stimulus. We have previously demonstrated an ameliorated syndrome and improved survival in mice with early administration of valproic acid (VPA), a broad-spectrum histone deacetylase inhibitor, while studies in humans have shown no benefit when anti-inflammatories are administered late. The current study tested the hypothesis that early treatment would improve outcomes in our gram-negative pneumonia-induced acute lung injury. Materials and methods Mice (C57BL/6) had 50 × 106 Escherichia coli (strain 19,138) instilled endotracheally and VPA (250 mg/kg) administered intraperitoneally 3, 4, 6, and 9 h (n = 12/group) later. Six hours after VPA administration, the animals were killed, and bronchoalveolar lavage (BAL) fluid interleukin-6 (IL-6), tumor necrosis factor, neutrophils and macrophages as well as theE coli colony-forming units were quantified. Plasma IL-6 was also measured. A separate group of mice (n = 12/group) were followed prospectively for 7 days to assess survival. Results BAL IL-6 and tumor necrosis factor as well as plasma IL-6 were significantly lower in the animals administered VPA within 3 h (P < 0.05) but not when administered later (4, 6, 9 h). There was no difference in the BAL E coli colony-forming units, macrophage, or neutrophil numbers at any time point. Survival improved only when VPA was administered within 3 h. Conclusions A narrow therapeutic window exists in this murine model of gram-negative pneumonia-induced acute lung injury and likely explains the lack of response in studies with late administration of anti-inflammatory therapies in clinical studies.

<div>Abstract<p><b>Purpose:</b> <i>KRAS</i>-activating mutations are the most common oncogenic driver in non–small cell lung cancer (NSCLC), but efforts to directly target mutant KRAS have proved a formidable challenge. Therefore, multitargeted therapy may offer a plausible strategy to effectively treat <i>KRAS</i>-driven NSCLCs. Here, we evaluate the efficacy and mechanistic rationale for combining mTOR and WEE1 inhibition as a potential therapy for lung cancers harboring <i>KRAS</i> mutations.</p><p><b>Experimental Design:</b> We investigated the synergistic effect of combining mTOR and WEE1 inhibitors on cell viability, apoptosis, and DNA damage repair response using a panel of human <i>KRAS-</i>mutant and wild type NSCLC cell lines and patient-derived xenograft cell lines. Murine autochthonous and human transplant models were used to test the therapeutic efficacy and pharmacodynamic effects of dual treatment.</p><p><b>Results:</b> We demonstrate that combined inhibition of mTOR and WEE1 induced potent synergistic cytotoxic effects selectively in <i>KRAS</i>-mutant NSCLC cell lines, delayed human tumor xenograft growth and caused tumor regression in a murine lung adenocarcinoma model. Mechanistically, we show that inhibition of mTOR potentiates WEE1 inhibition by abrogating compensatory activation of DNA repair, exacerbating DNA damage in <i>KRAS</i>-mutant NSCLC, and that this effect is due in part to reduction in cyclin D1.</p><p><b>Conclusions:</b> These findings demonstrate that compromised DNA repair underlies the observed potent synergy of WEE1 and mTOR inhibition and support clinical evaluation of this dual therapy for patients with <i>KRAS</i>-mutant lung cancers. <i>Clin Cancer Res; 23(22); 6993–7005. ©2017 AACR</i>.</p></div>