Effect of HLA Genotype on Anti-PD-1 Antibody Treatment for Advanced Renal Cell Carcinoma in the SNiP-RCC Study.

Immune checkpoint blockade therapies are widely used for cancer treatment, including advanced renal cell carcinoma (RCC). This study aimed to investigate the impact of zygosity in HLA genes and individual HLA genotypes on the efficacy of an anti-PD-1 Ab, nivolumab, in treating advanced RCC. Patient enrollment was conducted across 23 institutions in Japan from August 19, 2019, to September 30, 2020, with follow-up concluding on March 31, 2021. HLA genotype imputation of HLA-A, B, and C, DQB1, and DRB1 loci was performed. Among 222 patients, the presence of at least one homozygosity of the HLA-II allele significantly improved the best objective response (hazard ratio, 0.34; 95% confidence interval, 0.21-0.96; p = 0.042). The HLA evolutionary divergence (HED) of the HLA-A and HLA-B loci was higher than the HLA-C (p < 0.0001 and p < 0.0001, respectively), with high HED of the HLA-B locus correlating to clinical benefits in nivolumab treatment (hazard ratio, 0.44; 95% confidence interval, 0.21-0.90; p = 0.024) and improving cancer-specific survival compared with the low group (p = 0.0202). Additionally, high HED of the HLA-B locus was correlated with the number of infiltrated CD8+ cells in the tumor microenvironment (correlation coefficient, 0.4042). These findings indicate that the diversity of the HLA-B locus plays a significant role in the anti-tumor effect of nivolumab treatment in advanced RCC, potentially offering insights for improved risk stratification in nivolumab treatment and leading to better medical management of advanced RCC.

Impact of proton pump inhibitors on the efficacy of androgen receptor signaling inhibitors in metastatic castration-resistant prostate cancer patients.

BACKGROUND: Proton pump inhibitors (PPIs) are widely used due to their affordability and minimal severe side effects. However, their influence on the efficacy of cancer treatments, particularly androgen receptor signaling inhibitors (ARSIs), remains unclear. This study investigates the impact of PPI usage on the treatment outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC). METHODS: A total of 117 mCRPC patients were retrospectively analyzed and divided into two groups based on the concomitant use of PPI at the initiation of ARSI treatment: PPI+ (n = 38) and PPI- (n = 79). Patient characteristics, including age at ARSI treatment administered, prostate-specific antigen (PSA) value at ARSI treatment administered, International Society of Urological Pathology grade group at prostate biopsy, metastatic site at ARSI treatment administered, prior docetaxel (DTX) treatment, and type of ARSI (abiraterone acetate or enzalutamide) were recorded. Progression-free survival (PFS), overall survival (OS), and PSA response rates were compared between the two groups. Patients were further stratified by clinical background to compare PFS and OS between the two groups. RESULTS: The PPI- group exhibited significantly extended PFS and a trend toward improved OS. For PSA response (reduction of 50% or more from baseline), the rates were 62.3% and 45.9% in the PPI- group and the PPI+ group, respectively. For deep PSA response (reductions of 90% or more from baseline), the rates were 36.4% and 24.3% in the PPI- group and the PPI+ group, respectively. The effects were consistent across subgroups divided by prior DTX treatment and type of ARSI administered. CONCLUSIONS: The administration of PPIs appears to diminish the therapeutic efficacy of ARSIs in mCRPC patients. Further prospective studies are needed to confirm these findings and explore the biological mechanisms involved.

Prognosis based on postoperative PSA levels and treatment in prostate cancer with lymph node involvement.

BACKGROUND: The therapeutic role of pelvic lymph node dissection (PLND) during radical prostatectomy (RP) for prostate cancer is not established. In clinical practice, PLND is primarily performed in cases of high-risk prostate cancer. The detection of lymph node metastasis plays a crucial role in determining the need for subsequent treatments. This study aims to evaluate the prognosis of prostate cancer patients with lymph node involvement (LNI) by stratifying them based on postoperative prostate-specific antigen (PSA) levels to identify biomarkers that can guide postoperative treatment strategies. METHODS: Analysis was conducted on 383 patients, selected from 572 initially eligible, who underwent RP with LNI across 33 Japanese Urological Oncology Group institutions from 2006 to 2019. Patients were grouped according to postoperative PSA levels and salvage treatments received. Follow-up focused on castration resistance-free survival (CRFS), metastasis-free survival (MFS), and overall survival (OS). RESULTS: In the persistent PSA group (PSA ≥ 0.1 ng/mL), CRFS and MFS were significantly shorter compared to the non-persistent PSA group (PSA < 0.1 ng/mL), and there was a tendency for shorter OS. In the persistent PSA group, patients with postoperative PSA values above the median (PSA ≥ 0.52 ng/mL) showed shorter CRFS and MFS. Furthermore, in the PSA ≥ 0.52 group, androgen deprivation therapy (ADT) plus radiotherapy (RT) combination had prolonged CRFS and MFS compared with ADT alone. CONCLUSIONS: This study provides valuable insights into stratifying patients based on postoperative PSA levels to tailor postoperative treatment strategies, potentially improving the prognosis of prostate cancer patients with LNI.

Validation of schedules for optimal prostate-specific antigen monitoring after radical prostatectomy.

BACKGROUND: Early detection of biochemical recurrence (BCR) after radical prostatectomy (RP) is crucial for early treatment and improving survival outcomes. The optimal prostate-specific antigen (PSA) monitoring remains unclear, and several models have been proposed. We aimed to externally validate four models for optimal PSA monitoring after RP and propose modifications to improve them. METHODS: We reviewed the clinicopathological data of 896 patients who underwent robot-assisted RP between 2009 and 2022. We examined all PSA values and estimated the PSA value for four monitoring schedules at each time point in the virtual follow-up. We defined the ideal PSA for BCR detection between 0.2 and 0.4 ng/mL. RESULTS: During the median follow-up of 21.4 months, 128 (14.3%) patients presented BCR. The original and modified Keio models, National Cancer Center Hospital model, and American Urological Association/American Society for Radiation Oncology model detected BCR in 14 (10.9%), three (2.3%), 12 (9.4%), and 11 (8.6%) patients with PSA >0.4 ng/mL. Most patients experienced BCR detected with PSA >0.4 ng/mL during the first year postoperative. The modification of interval within 6 months postoperative avoided BCR detection with PSA >0.4 ng/mL within the first year postoperative in 8/9 (88.9%), 1/2 (50.0%), 5/6 (83.3%), and 4/4 (100%) for the original and modified Keio models, National Cancer Center Hospital model, and American Urological Association/American Society for Radiation Oncology model, respectively. CONCLUSION: We validated four models for PSA monitoring after RP to detect BCR and suggested modifications to avoid detections out of the desired range of PSA. These modifications could help to establish an optimal PSA monitoring schedule after RP.

HLA Class I Analysis Provides Insight Into the Genetic and Epigenetic Background of Immune Evasion in Colorectal Cancer With High Microsatellite Instability.

BACKGROUND & AIMS: A detailed understanding of antitumor immunity is essential for optimal cancer immune therapy. Although defective mutations in the B2M and HLA-ABC genes, which encode molecules essential for antigen presentation, have been reported in several studies, the effects of these defects on tumor immunity have not been quantitatively evaluated. METHODS: Mutations in HLA-ABC genes were analyzed in 114 microsatellite instability-high colorectal cancers using a long-read sequencer. The data were further analyzed in combination with whole-exome sequencing, transcriptome sequencing, DNA methylation array, and immunohistochemistry data. RESULTS: We detected 101 truncating mutations in 57 tumors (50%) and loss of 61 alleles in 21 tumors (18%). Based on the integrated analysis that enabled the immunologic subclassification of microsatellite instability-high colorectal cancers, we identified a subtype of tumors in which lymphocyte infiltration was reduced, partly due to reduced expression of HLA-ABC genes in the absence of apparent genetic alterations. Survival time of patients with such tumors was shorter than in patients with other tumor types. Paradoxically, tumor mutation burden was highest in the subtype, suggesting that the immunogenic effect of accumulating mutations was counterbalanced by mutations that weakened immunoreactivity. Various genetic and epigenetic alterations, including frameshift mutations in RFX5 and promoter methylation of PSMB8 and HLA-A, converged on reduced expression of HLA-ABC genes. CONCLUSIONS: Our detailed immunogenomic analysis provides information that will facilitate the improvement and development of cancer immunotherapy.

Effect of genetic polymorphisms on outcomes following nivolumab for advanced renal cell carcinoma in the SNiP-RCC trial.

BACKGROUND: Anti-PD-1 antibodies are widely used for cancer treatment including advanced renal cell carcinoma (RCC). However, their therapeutic and adverse effects vary among patients. This study aimed to identify genetic markers that predict outcome after nivolumab anti-PD-1 antibody treatment for advanced RCC. METHODS: This study was registered on the website of the University Hospital Medical Information Network (protocol ID, UMIN000037739). Patient enrollment was conducted at 23 institutions in Japan between August 19, 2019, and September 30, 2020. Patient follow-up ended on March 31, 2021. Patients were treated with nivolumab for advanced clear cell RCC. A genome-wide association study was performed in the development set, while genotyping of target regions in the validation set was undertaken. Single nucleotide polymorphisms (SNPs) in genes of interest CD274, PDCD1LG2 and PDCD1 were genotyped in the combined set. The primary endpoint was the association of SNPs with objective response following nivolumab treatment. As secondary endpoints, the associations of SNPs with radiographic progression-free survival (rPFS) and treatment-related grade ≥ 3 adverse events (AEs) were evaluated. RESULTS: A genome-wide association study followed by a validation study identified that SNPs in FARP1 (rs643896 and rs685736) were associated with objective response and rPFS but not AEs following nivolumab treatment. Furthermore, SNPs in PDCD1LG2 (rs822339 and rs1411262) were associated with objective response, rPFS, and AEs following nivolumab treatment. Genetic risk category determined according to the number of risk alleles in SNPs (rs643896 in FARP1 and rs4527932 in PDCD1LG2) excellently predicted objective response and rPFS in nivolumab treatment. CONCLUSION: This study revealed that SNPs in FARP1 and PDCD1LG2 were correlated with outcome in nivolumab treatment. The use of these SNPs may be beneficial in selecting appropriate treatment for individual patients and may contribute to personalized medicine.

Clinical factors for tumor response, progression, and survival in nivolumab for advanced renal cell carcinoma in the SNiP-RCC study.

BACKGROUND: This study is part of the SNPs in Nivolumab PD-1 inhibitor for RCC (SNiP-RCC). Here we aimed to reveal clinical factors for tumor response, progression, and survival in nivolumab for advanced clear cell renal cell carcinoma (RCC) in Japanese patients. METHODS: We included patients from 23 institutions in Japan. We evaluated the objective response, radiographic progression-free survival (PFS), overall survival (OS), and treatment-related grade ≥ 3 (serious adverse events [SAEs]). RESULTS: We included 222 patients. The median age was 69 years (interquartile range 62-74 years), and 71% of the patients were male. Pancreas metastasis, lung metastases, prior cytokine therapy, and SAEs, were associated with objective response. The median PFS was 18 months. Liver metastases (hazard ratio [HR], 1.61), age ≥ 75 (HR, 0.48), previous resection of primary sites (HR, 0.47), and SAEs (HR, 0.47) were independent prognostic factors for PFS. Karnofsky Performance Status <70 (HR, 2.90), high platelets (HR, 4.48), previous resection of primary sites (HR, 0.23), and pathological grade (HR, 0.19 for grade 2 and HR, 0.12 for grade 3) were independent prognostic factors for OS. SAEs were reported in 45 (20.3%) cases. In the group of patients with prior nephrectomy, SAEs were associated with objective response, PFS, and OS. CONCLUSION: The SNiP-RCC study identified clinical parameters correlated with treatment outcomes in Japanese patients with priorly treated advanced clear cell RCC undergoing nivolumab monotherapy.

Effect of HLA genotype on intravesical recurrence after bacillus Calmette-Guérin therapy for non-muscle-invasive bladder cancer.

The intravesical administration of bacillus Calmette-Guérin (BCG) is widely used to control the intravesical recurrence of non-muscle-invasive bladder cancer (NMIBC). This study aimed to reveal the effects of zygosity on human leukocyte antigen (HLA) genes and individual HLA genotypes on intravesical recurrence after intravesical BCG therapy for NMIBC. This study included Japanese patients who had received intravesical BCG for NMIBC. HLA genotyping of HLA-A, B, C, and DRB1 was performed. The effect of HLA zygosity and HLA genotype on intravesical recurrence was evaluated. Among 195 patients, those homozygous for the HLA-B supertype were more likely than those heterozygous for the HLA-B supertype to experience intravesical recurrence by univariate analysis (hazard ratio [HR], 95% confidence interval [CI]; 1.87, 1.14-3.05, P = 0.012) and multivariate analysis (HR, 95% CI; 2.26, 1.02-5.01, P = 0.045). Patients with B07 or B44 had a decreased risk of intravesical recurrence by univariate analysis (HR, 95% CI; 0.43, 0.24-0.78, P = 0.0056) and multivariate analysis (HR, 95% CI; 0.36, 0.16-0.82, P = 0.016). This study suggests the importance of the diversity and specificity of HLA-B loci in the antitumor effect of BCG immunotherapy for NMIBC. These findings may contribute to the delineation of risk strata for BCG therapy and improve the medical management of NMIBC.

The potential application of PD-1 blockade therapy for early-stage biliary tract cancer.

Biliary tract cancer (BTC) is an aggressive cancer with a poor prognosis partially due to the limited success in developing novel therapies, including molecularly targeted therapies and immunotherapies. Programmed cell death-1 (PD-1) blockade therapy is less effective against BTCs, necessitating further studies to understand the detailed immunological status of the tumor microenvironment (TME) in BTC. Here, we examined the immunological status of the TME in 37 BTCs with early- to late-stage disease, especially focusing on PD-1+CD8+ T cells. PD-1+CD8+ T cells, which are reportedly associated with the clinical response to PD-1 blockade therapy, were frequently observed in early-stage BTC and decreased with disease progression. Imaging mass cytometry for representative PD-1+CD8+TIL-high and -low patients demonstrated that tumor-infiltrating PD-1+CD8+ T cells were localized adjacent to tumor cells, whereas PD-1-CD8+ T cells were detected mainly in the stroma of the TME. In a mouse model, PD-1 expression by tumor-infiltrating CD8+ T cells was higher in smaller tumors and decreased with tumor growth. Consequently, large tumors became resistant to PD-1 blockade, while small tumors containing higher numbers of PD-1+CD8+ T cells were sensitive. We propose the important role of tumor-infiltrating PD-1+CD8+ T cells in anti-tumor immunity and the potential application of PD-1 blockade therapy for early-stage BTC.

Importance of 3ß-hydroxysteroid dehydrogenases and their clinical use in prostate cancer.

Androgen receptor signaling is crucial for the development of treatment resistance in prostate cancer. Among steroidogenic enzymes, 3ß-hydroxysteroid dehydrogenases (3ßHSDs) play critical roles in extragonadal androgen synthesis, especially 3ßHSD1. Increased expression of 3ßHSDs is observed in castration-resistant prostate cancer tumors compared with primary prostate tumors, indicating their involvement in castration resistance. Recent studies link 3ßHSD1 to resistance to androgen receptor signaling inhibitors. The regulation of 3ßHSD1 expression involves various factors, including transcription factors, microenvironmental influences, and posttranscriptional modifications. Additionally, the clinical significance of HSD3B1 genotypes, particularly the rs1047303 variant, has been extensively studied. The impact of HSD3B1 genotypes on treatment outcomes varies according to the therapy administered, suggesting the potential of HSD3B1 genotyping for personalized medicine. Targeting 3ßHSDs may be a promising strategy for prostate cancer management. Overall, understanding the roles of 3ßHSDs and their genetic variations may enable the development and optimization of novel treatments for prostate cancer.

Oxidative stress in peroxisomes induced by androgen receptor inhibition through peroxisome proliferator-activated receptor promotes enzalutamide resistance in prostate cancer.

Androgen receptor (AR)-targeting therapy induces oxidative stress in prostate cancer. However, the mechanism of oxidative stress induction by AR-targeting therapy remains unclear. This study investigated the mechanism of oxidative stress induction by AR-targeting therapy, with the aim to develop novel therapeutics targeting oxidative stress induced by AR-targeting therapy. Intracellular reactive oxygen species (ROS) was examined by fluorescence microscopy and flow cytometry analysis. The effects of silencing gene expression and small molecule inhibitors on gene expression and cytotoxic effects were examined by quantitative real-time PCR and cell proliferation assay. ROS induced by androgen depletion co-localized with peroxisomes in prostate cancer cells. Among peroxisome-related genes, PPARA was commonly induced by AR inhibition and involved in ROS production via PKC signaling. Inhibition of PPARα by specific siRNA and a small molecule inhibitor suppressed cell proliferation and increased cellular sensitivity to the antiandrogen enzalutamide in prostate cancer cells. This study revealed a novel pathway by which AR inhibition induced intracellular ROS mainly in peroxisomes through PPARα activation in prostate cancer. This pathway is a promising target for the development of novel therapeutics for prostate cancer in combination with AR-targeting therapy such as antiandrogen enzalutamide.

Salvage robot-assisted radical prostatectomy after carbon ion radiotherapy to the prostate.

PURPOSE: This study presents the surgical and oncological outcomes of salvage robot-assisted radical prostatectomy (RARP) after carbon ion radiotherapy at a single institution. METHODS: Patients who underwent salvage RARP for local recurrence after carbon ion radiotherapy at Kyushu University Hospital between 2020 and 2023 were included. A single surgeon performed salvage RARP with extended pelvic lymph node dissection. Clinicopathological characteristics and perioperative and postoperative outcomes were prospectively collected and electronically recorded. RESULTS: Ten cases were included. The preoperative clinical T-stage was T2, except for one case with T3a. The median console time was 171 min (range, 135-226 min). No severe perioperative or postoperative complications were noted. The pathological T-stage was T2, T3a, and T3b in four, four, and two cases, respectively. Biochemical recurrence was observed in one patient at 31.2 months after surgery. For patients with more than 1 year of follow-up, urinary continence recovery with ≤1 pad was achieved in two cases within 1 year, whereas four cases did not recover urinary continence within 1 year. CONCLUSIONS: This case series demonstrated the feasibility of salvage RARP after carbon ion radiotherapy. Although the urinary continence recovery was modest, short-term disease control was favorable.

The effect of human leukocyte antigen genotype on survival in advanced prostate cancer treated with primary androgen deprivation therapy: the KYUCOG-1401-A study.

BACKGROUND: Immune editing, in which human leukocyte antigens (HLA) have critical roles, has been suggested to shape the landscape of human cancer. This study prospectively investigated whether HLA gene zygosity is associated with the prognosis of primary androgen deprivation therapy in advanced prostate cancer. METHODS: KYUCOG-1401-A was conducted in conjunction with a prospective clinical trial (KYUCOG-1401). Among the patients enrolled in KYUCOG-1401 and treated with primary androgen deprivation therapy, only Japanese patients were included. HLA genotypes of HLA-A, B, C, DRB1, DQB1, and DPB1 were determined. The effect of divergence of HLA genotypes on time to progression, prostate cancer-specific survival, and overall survival was evaluated. RESULTS: Among 127 patients, homozygosity for HLA-DRB1 (HR, 95% CI; 4.05, 1.54-10.7, P = 0.0047) and HLA-DQB1 (HR, 95% CI; 3.75, 1.47-9.58, P = 0.0058) was associated with an increased risk of prostate cancer-specific mortality. Patients with higher HLA evolutionary divergence scores at HLA-DQB1 (HR, 95% CI; 0.90, 0.82-0.97, P = 0.0093) had lower risks of prostate cancer-specific mortality. Androgen-responsive gene sets were upregulated in CD4low and CD8low tumors in the prostate cancer cohort, but not in the bladder and kidney cancer cohorts. CONCLUSIONS: This study suggested that the diversity of HLA-II loci including HLA-DRB1 and HLA-DQB1 plays an important role in advanced prostate cancer survival, contributing to improved risk stratification in advanced prostate cancer. Moreover, it was shown that CD4+ T cells play an important role in androgen deprivation therapy, suggesting that immunotherapy targeting CD4+ T cells is promising for prostate cancer.

BATF epigenetically and transcriptionally controls the activation program of regulatory T cells in human tumors.

Regulatory T (Treg) cells suppress effective antitumor immunity in tumor-bearing hosts, thereby becoming promising targets in cancer immunotherapy. Despite the importance of Treg cells in tumor immunity, little is known about their differentiation process and epigenetic profiles in the tumor microenvironment (TME). Here, we showed that Treg cells in the TME of human lung cancers harbored a completely different open chromatin profile compared with CD8+ T cells, conventional CD4+ T cells in the TME, and peripheral Treg cells. The integrative sequencing analyses including ATAC, single-cell RNA, and single-cell ATAC sequencing revealed that BATF, IRF4, NF-κB, and NR4A were important transcription factors for Treg cell differentiation in the TME. In particular, BATF was identified as a key regulator, which leveraged Treg cell differentiation through epigenetically controlling activation-associated gene expression, resulting in the robustness of Treg cells in the TME. The single-cell sequencing approaches also revealed that tissue-resident and tumor-infiltrating Treg cells followed a common pathway for differentiation and activation in a BATF-dependent manner heading toward Treg cells with the most differentiated and activated phenotypes in tissues and tumors. BATF deficiency in Treg cells remarkably inhibited tumor growth, and high BATF expression was associated with poor prognosis in lung cancer, kidney cancer, and melanoma. These findings indicate one of the specific chromatin remodeling and differentiation programs of Treg cells in the TME, which can be applied in the development of Treg cell-targeted therapies.

Tim-3 mediates T cell trogocytosis to limit antitumor immunity.

T cell immunoglobulin mucin domain-containing protein 3 (Tim-3) negatively regulates innate and adaptive immunity in cancer. To identify the mechanisms of Tim-3 in cancer immunity, we evaluated the effects of Tim-3 blockade in human and mouse melanoma. Here, we show that human programmed cell death 1-positive (PD-1+) Tim-3+CD8+ tumor-infiltrating lymphocytes (TILs) upregulate phosphatidylserine (PS), a receptor for Tim-3, and acquire cell surface myeloid markers from antigen-presenting cells (APCs) through transfer of membrane fragments called trogocytosis. Tim-3 blockade acted on Tim-3+ APCs in a PS-dependent fashion to disrupt the trogocytosis of activated tumor antigen-specific CD8+ T cells and PD-1+Tim-3+ CD8+ TILs isolated from patients with melanoma. Tim-3 and PD-1 blockades cooperated to disrupt trogocytosis of CD8+ TILs in 2 melanoma mouse models, decreasing tumor burden and prolonging survival. Deleting Tim-3 in dendritic cells but not in CD8+ T cells impeded the trogocytosis of CD8+ TILs in vivo. Trogocytosed CD8+ T cells presented tumor peptide-major histocompatibility complexes and became the target of fratricide T cell killing, which was reversed by Tim-3 blockade. Our findings have uncovered a mechanism Tim-3 uses to limit antitumor immunity.

Lactic acid promotes PD-1 expression in regulatory T cells in highly glycolytic tumor microenvironments.

The balance of programmed death-1 (PD-1)-expressing CD8+ T cells and regulatory T (Treg) cells in the tumor microenvironment (TME) determines the clinical efficacy of PD-1 blockade therapy through the competition of their reactivation. However, factors that determine this balance remain unknown. Here, we show that Treg cells gain higher PD-1 expression than effector T cells in highly glycolytic tumors, including MYC-amplified tumors and liver tumors. Under low-glucose environments via glucose consumption by tumor cells, Treg cells actively absorbed lactic acid (LA) through monocarboxylate transporter 1 (MCT1), promoting NFAT1 translocation into the nucleus, thereby enhancing the expression of PD-1, whereas PD-1 expression by effector T cells was dampened. PD-1 blockade invigorated the PD-1-expressing Treg cells, resulting in treatment failure. We propose that LA in the highly glycolytic TME is an active checkpoint for the function of Treg cells in the TME via upregulation of PD-1 expression.

Highly immunogenic cancer cells require activation of the WNT pathway for immunological escape.

PD-1 blockade exerts antitumor effects by reinvigorating tumor antigen­specific CD8+ T cells. Whereas neoantigens arising from gene alterations in cancer cells comprise critical tumor antigens in antitumor immunity, a subset of non­small cell lung cancers (NSCLCs) harboring substantial tumor mutation burden (TMB) lack CD8+ T cells in the tumor microenvironment (TME), which results in resistance to PD-1 blockade therapy. To overcome this resistance, clarifying the mechanism(s) impairing antitumor immunity in highly mutated NSCLCs is an urgent issue. Here, we showed that activation of the WNT/ß-catenin signaling pathway contributed to the development of a noninflamed TME in tumors with high TMB. NSCLCs that lacked immune cell infiltration into the TME despite high TMB preferentially up-regulated the WNT/ß-catenin pathway. Immunologic assays revealed that those patients harbored neoantigen-specific CD8+ T cells in the peripheral blood but not in the TME, suggesting impaired T cell infiltration into the TME due to the activation of WNT/ß-catenin signaling. In our animal models, the accumulation of gene mutations in cancer cells increased CD8+ T cell infiltration into the TME, thus slowing tumor growth. However, further accumulation of gene mutations blunted antitumor immunity by excluding CD8+ T cells from tumors in a WNT/ß-catenin signaling-dependent manner. Combined treatment with PD-1 blockade and WNT/ß-catenin signaling inhibitors induced better antitumor immunity than either treatment alone. Thus, we propose a mechanism-oriented combination therapy whereby immune checkpoint inhibitors can be combined with drugs that target cell-intrinsic oncogenic signaling pathways involved in tumor immune escape.

Immune Suppression by PD-L2 against Spontaneous and Treatment-Related Antitumor Immunity.

PURPOSE: To evaluate the detailed immunosuppressive role(s) of PD-L2 given that its detailed role(s) remains unclear in PD-1 signal blockade therapy in animal models and humans. EXPERIMENTAL DESIGN: We generated mouse cell lines harboring various status of PD-L1/PD-L2 and evaluated the tumor growth and phenotypes of tumor-infiltrated lymphocytes using several PD-1 signal blockades in animal models. In humans, the correlation between immune-related gene expression and CD274 (encoding PD-L1) or PDCD1LG2 (encoding PD-L2) was investigated using The Cancer Genome Atlas (TCGA) datasets. In addition, PD-L1 or PD-L2 expression in tumor cells and CD8+ T-cell infiltration were assessed by IHC. RESULTS: In animal models, we showed that PD-L2 expression alone or simultaneously expressed with PD-L1 in tumor cells significantly suppressed antitumor immune responses, such as tumor antigen-specific CD8+ T cells, and was involved in the resistance to treatment with anti-PD-L1 mAb alone. This resistance was overcome by anti-PD-1 mAb or combined treatment with anti-PD-L2 mAb. In clinical settings, antitumor immune responses were significantly correlated with PD-L2 expression in the tumor microenvironment in renal cell carcinoma (RCC) and lung squamous cell carcinoma (LUSC). CONCLUSIONS: We propose that PD-L2 as well as PD-L1 play important roles in evading antitumor immunity, suggesting that PD-1/PD-L2 blockade must be considered for optimal immunotherapy in PD-L2-expressing cancers, such as RCC and LUSC.