Targeting leucine-rich repeat serine/threonine-protein kinase 2 sensitizes pancreatic ductal adenocarcinoma to anti-PD-L1 immunotherapy.

Pancreatic ductal adenocarcinoma (PDAC) is not sensitive to immune checkpoint blockade therapy, and negative feedback of tumor immune evasion might be partly responsible. We isolated CD8+ T cells and cultured them in vitro. Proteomics analysis was performed to compare changes in Panc02 cell lines cultured with conditioned medium, and leucine-rich repeat kinase 2 (LRRK2) was identified as a differential gene. LRRK2 expression was related to CD8+ T cell spatial distribution in PDAC clinical samples and upregulated by CD8+ T cells via interferon gamma (IFN-γ) simulation in vitro. Knockdown or pharmacological inhibition of LRRK2 activated an anti-pancreatic cancer immune response in mice, which meant that LRRK2 acted as an immunosuppressive gene. Mechanistically, LRRK2 phosphorylated PD-L1 at T210 to inhibit its ubiquitination-mediated proteasomal degradation. LRRK2 inhibition attenuated PD-1/PD-L1 blockade-mediated, T cell-induced upregulation of LRRK2/PD-L1, thus sensitizing the mice to anti-PD-L1 therapy. In addition, adenosylcobalamin, the activated form of vitamin B12, which was found to be a broad-spectrum inhibitor of LRRK2, could inhibit LRRK2 in vivo and sensitize PDAC to immunotherapy as well, which potentially endows LRRK2 inhibition with clinical translational value. Therefore, PD-L1 blockade combined with LRRK2 inhibition could be a novel therapy strategy for PDAC.

Improvement strategy for immune checkpoint blockade: A focus on the combination with immunogenic cell death inducers.

Cancer immunotherapies have yielded promising outcomes in various malignant tumors by blocking specific immune checkpoint molecules, such as programmed cell death 1 and cytotoxic T lymphocyte antigen 4. However, only a few patients respond to immune checkpoint blockade therapy because of the poor immunogenicity of tumor cells and immune-suppressive tumor microenvironment. Accumulating evidence suggests that chemotherapeutic agents, including oxaliplatin and doxorubicin, not only mediate direct cytotoxicity in tumor cells but also induce immunogenic cancer cell death to stimulate a powerful anti-cancer immune response in the tumor microenvironment. In this review, we summarize the recent advances in cancer combination therapy based on immune checkpoint inhibitors plus immunogenic cell death inducers. Despite some clinical failures and challenges, immunogenic cell death inducers have displayed great potential when combined with immune checkpoint inhibitors for anti-cancer treatment in both preclinical studies and clinical trials.

Dynamic profiling of immune microenvironment during pancreatic cancer development suggests early intervention and combination strategy of immunotherapy.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) has little response to immune checkpoint inhibitors. An in-depth understanding of the immune microenvironment from a comprehensive and dynamic perspective is critical to generate effective therapeutic strategies for PDAC. METHODS: Using mass cytometry and immunohistochemistry, we explored the dynamic changes of tumor-infiltrating immune cells during the development of PDAC in a genetically engineered mouse model (KrasG12D/+; Trp53R172H/+; Pdx1-cre) and human specimens. PD-L1-/- mice were crossed with KrasG12D/+; TgfßR2flox/flox; Ptf1a-cre mice to achieve early depletion of PD-L1 in pancreatic cancer. Combination therapy of Arginase-1 (Arg-1) inhibitor and anti-PD-1 mAb was validated in syngeneic mouse models. FINDINGS: Two different stages of immunosuppression with unique features were observed in both mouse model and human specimens. Early stage of immunosuppression featured highly abundant Tregs during acinar-to-ductal metaplasia, despite of a prominent and continuous presence of effector lymphocytes. The differentiation/activation branch of Ly-6C+ monocytes changed from a BST2+/MHC-II+ phenotype to an Arg-1+ phenotype over time during PDAC development. The late stage of immunosuppression thus featured the presence of a large number of myeloid suppressive cells together with a significant reduction of effector lymphocytes. Removal of PD-L1 from the beginning efficiently triggered anti-tumor immunity and significantly prolonged survival in PDAC-developing mice. Targeting Arg1+ macrophages with an Arg-1 inhibitor synergized with anti-PD-1 immunotherapy and led to PDAC-specific immune memory. INTERPRETATION: By demonstrating the coevolution of histopathology and immunology in PDAC, this study highlights the necessity and value of early intervention and combinational approach in leveraging immunotherapy to treat pancreatic cancer. FUNDING: A full list of funding bodies that contributed to this study can be found in the Acknowledgements section.

Oncolytic peptide LTX-315 induces anti-pancreatic cancer immunity by targeting the ATP11B-PD-L1 axis.

BACKGROUND: LTX-315 is an oncolytic peptide deriving from bovine lactoferrin, with the ability to induce cancer immunogenic cell death. However, the mechanism used by LTX-315 to trigger the antitumor immune response is still poorly understood. The expression of programmed cell death ligand 1 (PD-L1) largely determines the efficacy and effectiveness of cancer immunotherapies targeting this specific immune checkpoint. This study aimed to demonstrate the potential effect and mechanism of LTX-315 in PD-L1 inhibition-induced anti-pancreatic cancer immunity. METHODS: Both immunodeficient and immunocompetent mouse models were used to evaluate the therapeutic efficacy of monotherapy and combination therapy. Flow cytometry and immunohistochemistry were used to assess the immune microenvironment. Multiomic analysis was used to identify the potential target and down-streaming signaling pathway. Both in-house tissue microarray and open accessed The Cancer Genome Atlas data sets were used to evaluate the clinical relevance in pancreatic cancer prognosis. RESULTS: LTX-315 treatment inhibited PD-L1 expression and enhanced lymphocyte infiltration in pancreatic tumors. ATP11B was identified as a potential target of LTX-315 and a critical regulator in maintaining PD-L1 expression in pancreatic cancer cells. As regards the mechanism, ATP11B interacted with PD-L1 in a CKLF-like MARVEL transmembrane domain containing 6 (CMTM6)-dependent manner. The depletion of ATP11B promoted CMTM6-mediated lysosomal degradation of PD-L1, thus reactivating the immune microenvironment and inducing an antitumor immune response. The significant correlation among ATP11B, CMTM6, and PD-L1 was confirmed in clinical samples of pancreatic cancer. CONCLUSIONS: LTX-315 was first identified as a peptide drug inducing PD-L1 downregulation via ATP11B. Therefore, LTX-315, or the development of ATP11B-targeting drugs, might improve the efficacy of cancer immunotherapy.

A Seven-Gene Signature to Predict Prognosis of Patients With Hepatocellular Carcinoma.

Purpose: Hepatocellular carcinoma (HCC) is one of the most prevalent malignant diseases worldwide and has a poor prognosis. Gene-based prognostic models have been reported to predict the overall survival of patients with HCC. Unfortunately, most of the genes used in earlier prognostic models lack prospective validation and, thus, cannot be used in clinical practice. Methods: Candidate genes were selected from GEPIA (Gene Expression Profiling Interactive Analysis), and their associations with patients' survival were confirmed by RT-PCR using cDNA tissue microarrays established from patients with HCC after radical resection. A multivariate Cox proportion model was used to calculate the coefficient of corresponding gene. The expression of seven genes of interest (MKI67, AR, PLG, DNASE1L3, PTTG1, PPP1R1A, and TTR) with two reference genes was defined to calculate a risk score which determined groups of different risks. Results: Our risk scoring efficiently classified patients (n = 129) with HCC into a low-, intermediate-, and high-risk group. The three groups showed meaningful distinction of 3-year overall survival rate, i.e., 88.9, 74.5, and 20.6% for the low-, intermediate-, and high-risk group, respectively. The prognostic prediction model of risk scores was subsequently verified using an independent prospective cohort (n = 77) and showed high accuracy. Conclusion: Our seven-gene signature model performed excellent long-term prediction power and provided crucially guiding therapy for patients who are not a candidate for surgery.

Preoperative transarterial chemoembolization for barcelona clinic liver cancer stage A/B hepatocellular carcinoma beyond the milan criteria: a propensity score matching analysis.

BACKGROUND: Debate continues about the benefits of preoperative transarterial chemoembolization (TACE) for treatment of hepatocellular carcinoma (HCC). This study aimed to assess the impact of preoperative TACE on long-term outcomes after curative resection for HCC beyond the Milan criteria. METHODS: Patients who underwent HCC resection exceeding the Milan criteria without macrovascular invasion between 2015 and 2018 were identified (n = 393). Short- and long-term outcomes were compared between patients who underwent preoperative TACE and patients who did not before and after propensity score matching (PSM). Factors associated with recurrence after resection were analyzed. RESULTS: 100 patients (25.4%) underwent preoperative TACE. Recurrence-free survival (RFS) and overall survival (OS) were comparable with patients who underwent primary liver resection. 7 patients (7.0%) achieved total necrosis with better RFS compared with patients who had an incomplete response to TACE (P=0.041). PSM created 73 matched patient pairs. In the PSM cohort, preoperative TACE improved RFS (P=0.002) and OS (P=0.003). The maximum preoperatively diagnosed tumor diameter (HR 3.230, 95% CI: 1.116-9.353; P=0.031) and hepatitis B infection (HR 2.905, 95%CI: 1.281-6.589; P=0.011) were independently associated with favorable RFS after HCC resection. CONCLUSION: Preoperative TACE made no significant difference to perioperative complications and was correlated with an improved prognosis after surgical resection for patients with HCC beyond the Milan criteria.

Advantages of targeting the tumor immune microenvironment over blocking immune checkpoint in cancer immunotherapy.

Despite great success in cancer immunotherapy, immune checkpoint-targeting drugs are not the most popular weapon in the armory of cancer therapy. Accumulating evidence suggests that the tumor immune microenvironment plays a critical role in anti-cancer immunity, which may result in immune checkpoint blockade therapy being ineffective, in addition to other novel immunotherapies in cancer patients. In the present review, we discuss the deficiencies of current cancer immunotherapies. More importantly, we highlight the critical role of tumor immune microenvironment regulators in tumor immune surveillance, immunological evasion, and the potential for their further translation into clinical practice. Based on their general targetability in clinical therapy, we believe that tumor immune microenvironment regulators are promising cancer immunotherapeutic targets. Targeting the tumor immune microenvironment, alone or in combination with immune checkpoint-targeting drugs, might benefit cancer patients in the future.

Genomic investigation of co-targeting tumor immune microenvironment and immune checkpoints in pan-cancer immunotherapy.

Drugs that target immune checkpoints (ICPs) have become the most popular weapons in cancer immunotherapy; however, they are only beneficial for a small fraction of patients. Accumulating evidence suggests that the tumor immune microenvironment (TIME) plays a critical role in anti-cancer immunity. This study aimed to assess the potential merits and feasibility of combinational targeting ICPs and TIME in cancer immunotherapy. A total of 31 cancer type-specific datasets in TCGA were individually collected by the publicly available web servers for multiple bioinformatic analyses of ICPs and TIME factors. GEPIA was used to calculate the prognostic indexes, STRING was used to construct protein-protein interactions, cBioPortal was used for visualization and comparison of genetic alterations, and TISIDB was used to explore the correlation to tumor-infiltrating lymphocytes (TILs). Intriguingly, TIME factors were identified to have more global coverage and prognostic significance across multiple cancer types compared with ICPs, thus offering more general targetability in clinical therapy. Moreover, TIME factors showed interactive potential with ICPs, and genomic alteration of TIME factors coupled with that of ICPs, at least in pancreatic cancer. Furthermore, TIME factors were found to be significantly associated with TILs, including but not limited to pancreatic cancer. Finally, the clinical significance and translational potential of further combination therapies that incorporate both ICP inhibitors and TIME factor-targeted treatments were discussed. Together, TIME factors are promising immunotherapeutic targets, and a combination strategy of TIME factors-targeted therapies with ICP inhibitors may benefit more cancer patients in the future.