anti-PDL1 Therapy Research Articles

IL17A/CEBPβ/OPN/LYVE-1 axis inhibits antitumor immunity by promoting tumor-associated tissue resident macrophages

Tumor-associated macrophages (TAMs) are a critical component of the immunosuppressive tumor microenvironment, comprising monocyte-derived macrophages (MDM-TAMs) and tissue-resident macrophages (TRM-TAMs). Here, we discovered that TRM-TAMs mediate the pro-tumor effects of interleukin (IL)-17A and that IL-17A-driven tumor progression requires tumor cell production of osteopontin (OPN). Mechanistically, we identified CEBPβ as a transcription factor downstream of IL-17A in tumor cells and LYVE-1 as an OPN receptor on TRM-TAMs. IL-17A stimulates tumor cell production of OPN, and OPN/LYVE-1 signaling activatesthe JNK/c-Jun pathway, leading to the proliferation of immunosuppressive LYVE-1+ TRM-TAMs. Unlike its effect on LYVE-1+ TRM-TAMs, OPN interacts with α4β1 to promote the chemotaxis of LYVE-1- MDM-TAMs toward tumors. IL-17A neutralization, OPN inactivation in tumor cells, or LYVE-1 deletion in macrophages inhibited TAMs and enhanced anti-tumor immune responses and anti-PDL1 therapy. Thus, the IL-17A/CEBPβ/OPN/LYVE-1 axis offers a mechanism suppressing anti-tumor immune responses and, hence, an effective therapeutic target for cancer.

LSD1 inhibition improves efficacy of adoptive T cell therapy by enhancing CD8+ T cell responsiveness

The lysine-specific histone demethylase 1 A (LSD1) is involved in antitumor immunity; however, its role in shaping CD8 + T cell (CTL) differentiation and function remains largely unexplored. Here, we show that pharmacological inhibition of LSD1 (LSD1i) in CTL in the context of adoptive T cell therapy (ACT) elicits phenotypic and functional alterations, resulting in a robust antitumor immunity in preclinical models in female mice. In addition, the combination of anti-PDL1 treatment with LSD1i-based ACT eradicates the tumor and leads to long-lasting tumor-free survival in a melanoma model, complementing the limited efficacy of the immune or epigenetic therapy alone. Collectively, these results demonstrate that LSD1 modulation improves antitumoral responses generated by ACT and anti-PDL1 therapy, providing the foundation for their clinical evaluation.

Nilotinib boosts the efficacy of anti-PDL1 therapy in colorectal cancer by restoring the expression of MHC-I

BackgroundAlthough immune checkpoint inhibitors (ICIs) have revolutionized the landscape of cancer treatment, only a minority of colorectal cancer (CRC) patients respond to them. Enhancing tumor immunogenicity by increasing major histocompatibility complex I (MHC-I) surface expression is a promising strategy to boost the antitumor efficacy of ICIs.MethodsDual luciferase reporter assays were performed to find drug candidates that can increase MHC-I expression. The effect of nilotinib on MHC-I expression was verified by dual luciferase reporter assays, qRT-PCR, flow cytometry and western blotting. The biological functions of nilotinib were evaluated through a series of in vitro and in vivo experiments. Using RNA-seq analysis, immunofluorescence assays, western blotting, flow cytometry, rescue experiments and microarray chip assays, the underlying molecular mechanisms were investigated.ResultsNilotinib induces MHC-I expression in CRC cells, enhances CD8+ T-cell cytotoxicity and subsequently enhances the antitumor effects of anti-PDL1 in both microsatellite instability and microsatellite stable models. Mechanistically, nilotinib promotes MHC-I mRNA expression via the cGAS-STING-NF-κB pathway and reduces MHC-I degradation by suppressing PCSK9 expression in CRC cells. PCSK9 may serve as a potential therapeutic target for CRC, with nilotinib potentially targeting PCSK9 to exert anti-CRC effects.ConclusionThis study reveals a previously unknown role of nilotinib in antitumor immunity by inducing MHC-I expression in CRC cells. Our findings suggest that combining nilotinib with anti-PDL1 therapy may be an effective strategy for the treatment of CRC.

Diet restriction enhances the effect of immune checkpoint block by inhibiting the intratumoralmTORC1/B7-H3 axis.

Immune checkpoint blockade therapy has demonstrated significant therapeutic efficacy in certain cancer types; however, the impact of dietary restriction remains scarcely reported in this context. This study aimed to investigate the influence of dietary restriction on anti-PDL-1 therapy and the interplay of immune cells within this context. Using an anti-PDL-1 regimen combined with dietary restrictions, tumor progression was assessed in LLC-bearing mice. Flow cytometry was employed to analyze immune cell infiltration and differentiation levels within the tumor microenvironment. The expression of mTORC1/B7-H3 in tumors subjected to dietary restriction was also examined. LLC tumors with elevated B7-H3 expression were validated in mice to determine its inhibitory effect on immune cell proliferation and differentiation. A CD3/B7-H3 chimeric antibody was developed for therapeutic intervention in B7-H3 overexpressing tumors, with subsequent T cell responses assessed through flow cytometry. Dietary restriction potentiated the effect of anti-PDL1 therapy by suppressing the intratumorally mTORC1/B7-H3 axis. In vivo experiments demonstrated that elevated B7-H3 expression in tumors reduced infiltration and activation of CD8 + T cells within the tumor, while it did not affect tumor-infiltrating Tregs. In vitro studies revealed that high B7-H3 expression influenced the proliferation and activation of CD8 + T cells within a Coculture system. The constructed CD3/B7-H3 chimeric antibody prominently activated TCR within B7-H3 overexpressing tumors and impeded tumor progression. The findings suggest that dietary restriction enhances the efficacy of immune checkpoint blockade by modulating the intratumoral mTORC1/B7-H3 axis.

Novel markers of MCL1 inhibitor sensitivity in triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) is an aggressive breast cancer sub-type with limited treatment options and poor prognosis. Currently, standard treatments for TNBC include surgery, chemotherapy, and anti-PDL1 therapy. These therapies have limited efficacy in advanced stages. Myeloid-cell leukemia 1 (MCL1) is an anti-apoptotic BCL2 family protein. High expression of MCL1 contributes to chemotherapy resistance and is associated with a worse prognosis in TNBC. MCL1 inhibitors are in clinical trials for TNBC, but response rates to these inhibitors can vary and predictive markers are lacking. Currently, we identified a 4-member (AXL, ETS1, IL6, EFEMP1) gene signature (GS) that predicts MCL1 inhibitor sensitivity in TNBC cells. Factors encoded by these genes regulate signaling pathways to promote MCL1 inhibitor resistance. Small molecule inhibitors of the GS factors can overcome resistance and sensitize otherwise resistant TNBC cells to MCL1 inhibitor treatment. These findings offer insights into potential therapeutic strategies and tumor stratification for MCL1 inhibitor use in TNBC.

Abstract LB123: Conditionally active, therapeutic lymphotoxin beta receptor (LTBR) agonist bispecific antibodies for induction of tertiary lymphoid structures in the treatment of solid tumors

Abstract The presence of tertiary lymphoid structures (TLS) and associated high endothelial venules (HEV) in the tumor microenvironment strongly correlates with improved prognosis and treatment outcomes across a wide range of solid tumors. These clinical observations, now replicated repeatedly, highlight the therapeutic potential of induction of TLS and/or boosting TLS functions, which include acting as a point of entry and education for immune effector cells locally in the tumor. Lymphotoxin beta receptor (LTBR) signalling is essential for lymphoid structure development and the ectopic expression of its ligands, lymphotoxin αβ and LIGHT, is sufficient for TLS formation in vivo but challenging for therapeutic development. Here we present human bispecific antibodies (bsAbs) which conditionally agonize LTBR on co-engagement of fibroblast activation protein (FAP), a tumor microenvironment specific marker expressed by cancer associated fibroblasts. In vitro characterisation of these therapeutic bsAbs is presented, along with in vivo preclinical evaluation of surrogate bsAbs binding to mouse LTBR and mouse FAP in murine tumor models. Results - Therapeutic bsAbs were identified following an extensive screening campaign combining LTBR and FAP binding arms on an engineered human Fc with minimal FcyR binding. In vitro assays using primary cancer associated fibroblasts and LTBR positive cells demonstrated conditionally active therapeutic bsAbs potently activated LTBR in the presence of FAP expressing cells, whereas in the absence of FAP expressing cells no activity was observed. Surrogate bsAbs demonstrated monotherapy activity and led to tumor regressions in combination with anti-PDL1 therapy in an EMT6 mouse model, a syngeneic orthotopic model of breast cancer. Flow cytometry of endpoint tumors showed robust formation of HEVs and increased infiltration of T cells and B cells. In addition, we demonstrate that LTBR agonism, but not PD-L1 inhibition, leads to the formation of TLS structures containing organized lymphocyte aggregates with the appearance of germinal centres and accumulations of T and B cells in a mouse model of lung cancer. In conclusion, conditionally active FAP-LTBR bispecifics activate LTBR in the tumor microenvironment and induce HEV and TLS formation, leading to potent monotherapy activity in vivo, and to tumor regression in combination with PD-L1. These data support the development of FAP-LTBR bispecifics for the treatment of solid tumors as monotherapy and in combination with standard of care. Citation Format: Marta Lewandowska, Fevzi Demircioglu, Lucy Penfold, Rebecca B. Riddle, Sameer Sirohi, Floriane Laurent, Richard Brown, Sonia Bains, Dara Bevan, Emma Stanley, Jeanine Pignatelli, James W. Legg, Ray Jupp. Conditionally active, therapeutic lymphotoxin beta receptor (LTBR) agonist bispecific antibodies for induction of tertiary lymphoid structures in the treatment of solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB123.

Lanosterol synthase deficiency promotes tumor progression by orchestrating PDL1-dependent tumor immunosuppressive microenvironment.

Lipid metabolic reprogramming is closely related to tumor progression with the mechanism not fully elucidated. Here, we report the immune-regulated role of lanosterol synthase (LSS), an essential enzyme in cholesterol synthesis. Database analysis and clinical sample experiments suggest that LSS was lowly expressed in colon and breast cancer tissues, which indicates poor prognosis. The biological activity of tumor cell lines and tumor progression in NOD scid gamma (NSG) mice were not affected after LSS knockdown, whereas LSS deficiency obviously aggravated tumor burden in fully immunized mice. Flow cytometry analysis showed that LSS knockdown significantly promoted the formation of tumor immunosuppressive microenvironment, characterized by the increase in M2 macrophages and polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), as well as the decrease in anti-tumoral T lymphocytes. With the inhibition of myeloid infiltration or loss function of T lymphocytes, the propulsive effect of LSS knockdown on tumor progression disappeared. Mechanistically, LSS knockdown increased programmed death ligand 1 (PDL1) protein stability by 2,3-oxidosqualene (OS) binding to PDL1 protein. Anti-PDL1 therapy abolished LSS deficiency-induced immunosuppressive microenvironment and cancer progression. In conclusion, our results show that LSS deficiency promotes tumor progression by establishing an OS-PDL1 axis-dependent immunosuppressive microenvironment, indicative of LSS or OS as a potential hallmark of response to immune checkpoint blockade.

Adoptive cell transfer therapy with ex vivo primed peripheral lymphocytes in combination with anti-PDL1 therapy effectively inhibits triple-negative breast cancer growth and metastasis

BackgroundAdoptive cell transfer cancer immunotherapy holds promise for treating disseminated disease, yet generating sufficient numbers of lymphocytes with anti-cancer activity against diverse specificities remains a major challenge. We recently developed a novel procedure (ALECSAT) for selecting, expanding and maturating polyclonal lymphocytes from peripheral blood with the capacity to target malignant cells.MethodsImmunodeficient mice were challenged with triple-negative breast cancer cell lines or patient-derived xenografts (PDX) and treated with allogeneic or autologous ALECSAT cells with and without anti-PDL1 therapy to assess the capacity of ALECSAT cells to inhibit primary tumor growth and metastasis.ResultsALECSAT mono therapy inhibited metastasis, but did not inhibit primary tumor growth or prolong survival of tumor-bearing mice. In contrast, combined ALECSAT and anti-PDL1 therapy significantly inhibited primary tumor growth, nearly completely blocked metastasis, and prolonged survival of tumor-bearing mice.ConclusionsCombined ALECSAT and anti-PDL1 therapy results in favorable anti-cancer responses in both cell line-derived xenograft and autologous PDX models of advanced triple-negative breast cancer.

The deubiquitinating enzyme USP44 suppresses hepatocellular carcinoma progression by inhibiting Hedgehog signaling and PDL1 expression

Hepatocellular carcinoma (HCC) is one of the deadliest malignancies in the world. Research into the key genes that maintain the malignant behavior of cancer cells is crucial for the treatment of HCC. Here, we identified ubiquitin‐specific peptidase 44 (USP44), a member of the deubiquitinase family, as a novel regulator of HCC progression. The tumor suppressive function of USP44 was evaluated in a series of in vitro and in vivo experiments. Through quantitative proteomics examination, we demonstrated that USP44 inhibits HCC PDL1 expression by downregulating the Hedgehog (Hh) signaling pathway. Mechanistically, we found that USP44 directly interacts with Itch, an E3 ligase involved in Hh signaling, and promotes the deubiquitination and stabilization of Itch. These events result in the proteasomal degradation of Gli1 and subsequent inactivation of Hh signaling, which ultimately suppresses PDL1 expression and the progression of HCC. Furthermore, the HCC tissue microarray was analyzed by immunohistochemistry to evaluate the pathological relevance of the USP44/Itch/Gli1/PDL1 axis. Finally, the Gli1 inhibitor GANT61 was found to act in synergy with anti-PDL1 therapy. Overall, USP44 can act as a suppressive gene in HCC by modulating Hh signaling, and co-inhibition of Gli1 and PDL1 might be an effective novel combination strategy for treating HCC patients.

A Specialized CD4+ T-Cell Subset Protects Residual Leukemic Cells from Immune Surveillance, Enabling Relapse

Outcomes for patients with acute lymphoblastic leukemia (ALL) continue to improve in the era of immune- therapies. Despite this, measurable residual disease (MRD) frequently persists after frontline treatment, necessitating allogeneic hematopoietic stem cell transplantation or prolonged chemotherapy lasting multiple years. Relapse remains common and is associated with long-term survival rates of <25%. This emphasizes the need for research into fundamental mechanisms that enable the persistence of leukemic blasts. We previously showed that adding anti-PDL1 therapy to the tyrosine kinase inhibitor nilotinib improved survival from 10% to 70% in a murine model of BCR-ABL+ ALL. This effect was abrogated in the absence of CD4 T cells, suggesting a key role for CD4 T cells in anti-leukemia immunity. Persisting MRD in the absence of PDL1 blockade was associated with the polyclonal expansion of FOXP3- CD4 T-cells. These CD4s expressed high levels of the suppressive cytokine IL10, and loss of key helper molecules such as CD40L. In contrast, successful treatment with PDL1 blockade correlated with oligoclonal expansion of a CD4+ T-cell subset with preserved CD40L expression and diminished IL10. The observed IL10+ FOXP3- CD4 T-cell phenotype implies a T-regulatory type 1 (Tr1) identity. Importantly, a specialized Tr1 subset has been shown to eliminate mutation-harboring hematopoietic stem cells (HSCs), demonstrating a role for surveillance and leukemia prevention by Tr1s in the HSC niche. Tr1s convey pro-proliferative and differentiation signals towards mutation-harboring HSCs, driving their development into short-lived myeloid blasts. Tr1s in the HSC niche secrete high levels of IL10, apparently to minimize excess inflammation while eliminating mutated HSCs. In our current proposal, we hypothesize that the pro-proliferative and immunosuppressive signals of Tr1s are co-opted by residual acute lymphoblastic leukemia cells, maladaptively protecting them from immune attack and eradication. To investigate this hypothesis, we made a novel transgenic mouse (HV1) that harbors CD4 T-cells with a fixed TCR derived from the oligoclonally expanded CD4+ T-cells that we observed during treatment with anti-PDL1 blockade. HV1 CD4 T-cells specifically recognized and expanded in response to BCR-ABL+ ALL cells. HV1 cells remained largely FOXP3-negative and demonstrated an increase in IL10 expression with concordant loss of CD40L during leukemia progression. scATACSeq studies revealed that naïve HV1 cells develop into 5 distinct subsets during leukemia challenge in vivo (Fig. 1). Accessible chromatin regions (ACRs) of IL10, EOMES and other Tr1-like genes were high in clusters 1,2, and 5. Interestingly, clusters 1 and 5 did not have a loss of ACRs in genes associated with helper/effector function (CD40L, IFNγ, TNF). Functional studies verified that co-culture of CD4 T-cells with BCR-ABL+ ALL cells induced CD4s to suppress bystander CD8+ T-cells. Adoptive transfer of HV1 cells prolonged survival of mice bearing BCR-ABL+ ALL, but was non-curative, consistent with reprogramming of HV1 cells to an IL10+ suppressive phenotype. These findings imply that anti-leukemia CD4 T-cells in the presence of leukemia initially develop into heterogenous pro-helper/cytotoxic subsets. Chronic exposure to leukemia drives most of these early subsets to terminally differentiate into IL10+/FOXP3- suppressive Tr1s. These Tr1s do not bear classic hallmarks of exhaustion (e.g. epigenetic silencing of effector cytokines) but instead phenocopy a class of CD4s that normally guards the HSC niche. Anti-PDL1 blockade may function in this context by clonally expanding progenitor helper/cytotoxic leukemia-specific CD4s, tilting the local balance away from IL10+ populations. This mechanism is distinct from rescue of early-exhausted T-cell populations, which is a well-accepted explanation for the effects of checkpoint blockade on CD8+ T-cells in solid tumor settings. Our results imply a novel mechanism underlying anti-PDL1 checkpoint blockade clinical efficacy, which may be therapeutically exploited to eradicate measurable residual disease.

Enhancing Immune-Mediated Radiotherapy Efficacy in Murine Models of Head and Neck Cancer through Peroxisome Proliferator-Activated Receptor Modulation

The tumor microenvironment (TME) in HPV-unrelated head and neck cancer (HNC) is considered to be immunologically "cold," and immunometabolic adaptations to radiotherapy (RT) can exacerbate these conditions and lead to radioresistance. Peroxisome proliferator-activated receptor-α (PPARα) agonism may improve the immune response to RT by reducing glucose scarcity through upregulation of fatty acid utilization in cancer cells. Our clinical trial data shows that high serum oleic acid (OA), a PPAR ligand, correlates with response to radioimmunotherapy. Orthotopic buccal tumor implantations of MOC2 and LY2 HNC cell lines were performed in C57BL/6 and BALB/c mice, respectively. Mice were placed on a high OA diet (38% kcal from OA) 3 weeks prior to tumor implantation. Control diet consisted of 1% kcal from OA. In vitro RT was performed to characterize the metabolic effects on the cancer cell lines. For in vivo studies, tumors were irradiated upon reaching 100 mm^3 with three 8 Gy fractions, given every 4-5 days. The PPARα agonist fenofibrate (FF, 100mg/kg/day) was given via oral gavage or intraperitoneal injection starting 5 days after RT. Tumor volume and overall survival were measured as objective outcomes, and flow cytometry was used to characterize the immune landscape of the tumor, blood, and lymph nodes. Mass spectrometry was employed for bulk proteomics and metabolomics on serum samples, and stable isotope labeling was performed on CD8 T cells from treated mice ex vivo. Extracellular flux analyses were performed on tumor cells and CD8 T cells to determine metabolic phenotypic changes. In vitro cytotoxicity was met for MOC2 and LY2 cancer cells in 100 uM FF and OA in comparison to solvent (p<0.01). Extracellular flux analyses show that RT upregulates the glycolytic phenotype of MOC2 and LY2 cancer cells; and that FF and/or OA decrease the glycolytic capacity of the cancer cells. Ex vivo extracellular flux analyses showed increased glycolytic capacity of CD8 T cells in mice treated with FF in comparison to RT alone. RT in combination with FF significantly improved tumor volume response in comparison to RT alone (mean 99.4 vs 182.7 mm^3, p = 0.001) and was comparable to combination radioimmunotherapy (with anti-PDL1 therapy; mean 99.4 vs. 132.3 mm^3). Unexpectedly, OA negated this improvement in efficacy in both MOC2 and LY2 tumor models; mice on the high OA diet had significantly higher average body weight (p<0.01). Significant changes in adaptive immune response were observed within the TME with the addition of FF. This was mirrored by changes in serum metabolomics. PPARα agonism improved the efficacy of RT in murine HNC models and could be considered in future translational clinical trial design.

Turning up the heat: CTLA4 blockade in urothelial cancer.

Anti-PD1 and anti-PDL1 monotherapies have shown clinical efficacy in stage IV urothelial cancer and are integrated into current clinical practice. However, only a small number of the patients treated with single-agent checkpoint blockade experience an antitumour response. Insufficient priming or inhibitory factors in the tumour immune microenvironment might have a role in the lack of response. CTLA4 is an inhibitory checkpoint on activated T cells that is being studied as a therapeutic target in combination with anti-PD1 or anti-PDL1 therapies in advanced urothelial cancer. In locally advanced urothelial cancer, this combination approach has shown encouraging antitumour effects when administered pre-operatively. We believe that the presence of pre-existing intratumoural T cell immunity is not a prerequisite for response to combination therapy and that the additional value of CTLA4 blockade might involve the broadening of peripheral T cell priming, thereby transforming immunologically cold tumours into hot tumours.

Frequent expression of PD-L1 in lymphocyte-rich hepatocellular carcinoma: A report of 4 cases

BackgroundProgrammed death ligand 1 (PD-L1) is an immune checkpoint inhibitor. PD-L1 binds to its receptor programmed death receptor (PD-1) expressed by immune cells and plays a key role in regulating immune responses. Engagement of PD-L1 on cancer cells and PD-1 on immune cells avoid destruction of tumour cells by immune cells. Immunostaining with PD-L1 has been suggested as a biomarker predictive of antiPD-L1 immunotherapy. Lymphocyte-rich hepatocellular carcinoma (LrHCC) is a rare histological HCC subtype which is characterised by neoplastic epithelial cells intermixed with numerous immune cells. MethodsHere in we investigated immunohistochemical PD-L1 expression in 4 cases of LrHCC. Tumour proportion score (TPS) and immune cell score was recorded. Immunophenotypic characterization of the tumour and inflammatory cells was also done. Epstein-Barr encoding region (EBER) in situ hybridization (ISH) assay as performed in all four tumours. ResultsExpression of PD-L1 was demonstrated in tumour epithelial cells and immune cells in all four cases. Incomplete to membranous staining was demonstrated in the tumour cells. Tumour proportion score (TPS) was 1.2–20 %. Immune cells demonstrated membranous and cytoplasmic immunostaining. Immune cell score was ≥1 % to >10 %. ConclusionPD-L1 expression in both tumour and immune cells suggests distinct immunogenic feature and potential role of antiPD-L1 therapies in cases with inoperable disease.

Phase 1 trial of avelumab with hypofractionated thoracic radiation therapy (HT-RT) in patients with metastatic soft-tissue sarcomas (mSTS).

11552 Background: Combining HT-RT with anti PD-L1 therapy may enhance local and distant tumour control in mSTS. This was a Phase 1 trial to evaluate the safety, tolerability, and efficacy of avelumab in patients with mSTS. Methods: This was a single centre phase 1 trial of avelumab with HT- RT in patients with mSTS (NCT03602833). Patients &gt; 18 years with at least 2 pulmonary metastases, ECOG performance status 0-1 were eligible between Oct 2018-Apr 22. Patients received HT-RT (36 Gy in 12 fractions), with concurrent intravenous avelumab (10 mg/kg q14d) until disease progression. The primary end point was safety of avelumab with HT-RT. Secondary endpoints included local control rate at 3 months. Dose limiting Toxicity (DLT) assessed from start of HR-CT and avelumab up to Cycle 7 avelumab and defined as: ≥ G2 pneumonitis, ≥ G2 myelitis, ≥ G3 non-haem toxicity, ≥ any other G4 and/or HT-RT interruption &gt; 5 days. Response was evaluated using the Response Evaluation Criteria in Solid Tumors (RECIST). Results: 12 patients were treated in this trial. Histological subtypes: leiomyosarcoma (n = 2), undifferentiated pleomorphic sarcoma (n = 2), and spindle cell sarcoma (n = 2). The median age was 57.5 (37-68) years, 7 were female (58%). All patients had lung metastases. 1 previously received SBRT to the lung, and 5 (42%) patients had received prior systemic treatment. 12 patients received at least one cycle of avelumab, median 9 (range: 1-37), and treatment was discontinued in 11 (92%) patients; 10 (83%) stopping for progressive disease, 1 (8%) patient for G4 immune-mediated hepatitis after DLT period and 1 patient completed and continues on compassionate-use avelumab. Eleven (92%) completed radiotherapy (36 Gy, 12 fractions). No DLTs or treatment-related deaths were observed. HT-RT toxicity: 3 G2 acute (1 oesophagitis, 2 skin) noted up to 11 weeks. 13 G1 late toxicities (5 pneumonitis, 5 skin, 1 cardiac, 1 myelitis, 1 oesophagitis) reported. Avelumab toxicities: 2 G3 (1 ALT rise, 1 viral infection) and 3 G4 (1 AST rise, 1 hepatitis, 1 sepsis) reported after DLT observation period. The median follow-up was 21.8 (range 3.2-31.9) months with a 3-month local control rate of 50% (95% CI, 21%-74%). RECIST responses at 3 months were 0 CR, 1 (8%) PR, 5 (42%) SD and 5 (42%) PD. Conclusions: Avelumab in combination with thoracic radiotherapy was safe with encouraging anti-tumour activity in patients with metastatic soft-tissue sarcomas. Additional molecular biomarker analyses are in progress. Clinical trial information: NCT03602833 .

ARC-10: A phase 3 study to evaluate zimberelimab + domvanalimab versus pembrolizumab in front-line, PD-L1-high, locally advanced or metastatic non–small-cell lung cancer.

TPS9148 Background: Despite improvements in the management of locally advanced or metastatic non–small cell lung cancer (NSCLC) from programmed cell death/ligand protein 1 (PD-[L]1) inhibition, there remains an unmet need for improved treatment options. PD-L1 expression is a known biomarker of response to anti–PD-L1 therapies in metastatic NSCLC. The combination of PD-1 inhibition with inhibition of the immunosuppressive T cell Immunoglobulin and ITIM domain (TIGIT) pathway is associated with improved response and prolonged progression-free survival in patients with advanced NSCLC. Domvanalimab (dom) is an Fc-silent humanized IgG1 monoclonal antibody (mAb) that blocks TIGIT, thereby reducing immunosuppression of T/natural killer (NK) cells and promoting antitumor activity. Zimberelimab (zim) is an mAb that binds to PD-1 on T/NK cells, preventing PD-L1-mediated immunosuppressive effects and resulting in tumor cell death. This phase 3 study will investigate the efficacy and safety of combination therapy with dom + zim compared with pembrolizumab monotherapy in patients with PD-L1-high NSCLC. Methods: ARC-10 (NCT04736173) is a global, phase 3, randomized, multicenter, open-label study. Eligible patients are adults with histologically confirmed, treatment-naive, locally advanced or metastatic, squamous or non-squamous NSCLC with ≥1 measurable lesion(s) per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1, high expression of PD-L1 (tumor cells [TC] ≥50%), and an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. Patients must not have genomic tumor aberrations for which targeted therapies are approved and available (eg, EGFR, ALK, ROS, BRAF, NTRK). Approximately 600 patients will be randomized 1:1 to receive combination therapy with dom + zim (dom 1200 mg intravenous [IV] once every 3 weeks [Q3W] + zim 360 mg IV Q3W) or pembrolizumab monotherapy (200 mg IV Q3W) for 21-day cycles until disease progression, intolerance, or a maximum of 35 cycles. Randomization will be stratified by ECOG performance status (0 vs 1), geographical region (Asia vs non-Asia), and histology (squamous vs non-squamous). The primary efficacy endpoint is overall survival. Secondary efficacy endpoints include blinded independent central review of progression-free survival and confirmed overall response rate according to RECIST v1.1. Safety endpoints include the presence of treatment-emergent adverse events and laboratory parameters. Health-related quality of life will be assessed by measuring the time to first symptom deterioration in the NSCLC-Symptom Assessment Questionnaire total score. Study recruitment is planned in Asia, North and South America, Africa, and Europe. Clinical trial information: NCT04736173 .

Absence of Toll-like receptor 5 confers survival in mice bearing ovarian tumors treated with anti-PD-L1

Abstract Ovarian cancer accounts for more deaths than any other cancer of the female reproductive system. Patients bearing ovarian tumors infiltrated with high frequencies of T cells associate with a greater survival probability. However, therapies targeting T cells in ovarian cancers are ineffective. We observed in models of late-stage murine ovarian cancer that in absence of Toll-Like Receptor 5 (TLR5) signaling, anti-PD-L1 promotes significant survival and protection against tumor rechallenge. Ovarian tumors from rechallenged TLR5KO mice exhibited significantly higher frequency/number of CD8 T cells expressing functional and activation markers. Thus, in the absence of TLR5 signaling, T cells mount/maintain a stronger response to ovarian tumors after inhibitory receptor blockade. Furthermore, protection against tumor progression in TLR5KO mice corresponds with a significant increase in tumor infiltrating cross presenting and IL-12 producing Dendritic cells (DCs). Additionally, in CD11c Cre x TLR5 fl/fl mice, whose DCs lack TLR5 expression, PD-L1-blockade mediated extended survival in ovarian tumor-bearing mice. Using a mixed bone marrow chimera approach, we demonstrate that direct TLR5 signaling functionally alters DCs to become more suppressive in the tumor microenvironment, impacting T cell differentiation and anti-tumor activity, thereby reducing survival during aPD-L1 therapy. Clinically, roughly 7.5% of the general population harbor a TLR5 SNP that diminishes TLR5 signaling and is associated with increased long-term survival for ovarian cancer patients. Therefore, patients who express the TLR5 SNP may immediately benefit from anti-PDL1 therapy and those without the SNP, TLR5 antagonism. NIH/NCI 1R01CA253285 UVA Farrow Fellowship

Abstract 1863: Evaluation of BDB101, a first-in-class TLR7/8 dual agonist conjugated to an anti-PD-L1 mAb, in cancer treatment

Abstract Background Responses to antiPDL1 checkpoint inhibitors (CPIs) in many tumors are governed by the PDL1 expression on tumor and immune cells in the tumor microenvironment (TME). Increasing PDL1 expression on cells may enhance the response to CPIs. Tolllike receptor (TLR) agonists have shown to induce PDL1 expression in the TME and may enhance the antitumor effects of CPIs. The effective dose of TLR agonist administered to patients is limited by systemic toxicities. To overcome this limitation, one approach is to conjugate the TLR agonist to an antibody. This allows for delivery and release of higher doses of the TLR agonist in the TME while limiting systemic exposure.BDB001 is an intravenously (IV) delivered TLR7/8 dual agonist that activates both the innate and adaptive immune system. In clinical trials, BDB001 has been well tolerated and shown promising antitumor responses in monotherapy and in combination with antiPDL1 therapy (Patel M. et al, SITC 2020 and SITC 2021). To further enhance the antitumor effect and allow for increased concentration of the TLR7/8 dual agonist in the TME, we developed BDB101, a proprietary firstinclass TLR7/8 dual agonist - antiPDL1 monoclonal antibody (mAb) conjugate using our TollLike receptor Agonist Conjugate (TLAC) platform. Here we report on the preclinical and nonhuman primate (NHP) evaluation of BDB101. Methods BDB101 utilizes a cleavable linker, allowing for the TLR7/8 dual agonist payload to be released in the TME and enabling a bystander effect. BDB101 was assessed for in vitro TLR7/8 dual agonist activity and PDL1 binding, and in vivo antitumor efficacy in immune competent mouse models. The pharmacokinetic and pharmacodynamic effects of BDB101 was evaluated in NHP. Results The conjugated TLR7/8 dual agonist did not change the PDL1 binding specificity of the antibody, and the uncleaved conjugate did not activate TLR7 or TLR8. In the C26 mouse model, a BDB101 mouse surrogate showed a significantly more robust antitumor effect compared to the TLR7/8 dual agonist or the antiPDL1 mAb alone. In NHP, a single IV infusion of BDB101 showed no significant differences in PK parameters between BDB101 and the total antiPDL1 mAb. BDB101 demonstrated remarkable in vitro stability in human plasma for up to 21 days. In NHP, BDB101 was also very stable with minimal release of free TLR7/8 dual agonist payload. Pharmacodynamic studies in NHP were consistent with PK behavior. Conclusions BDB101 exhibits robust preclinical efficacy and prolonged stability in NHP. The low rate of free TLR7/8 dual agonist payload released into the systemic circulation from the conjugated form of BDB101, should minimize the risk of systemic TLR7/8 dual agonist exposure, while maintaining the ability to deliver the payload to the TME. These results indicate that BDB101 will likely have a good in vivo therapeutic window and strongly support the clinical development of BDB101. Citation Format: Jing Yang, Robert H. Andtbacka, Walter Lau, Lixin Li. Evaluation of BDB101, a first-in-class TLR7/8 dual agonist conjugated to an anti-PD-L1 mAb, in cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1863.

Abstract 6653: Analysis of selective response of anti-PD-L1 treatment in huPBMC-NCG mice reconstituted with different donors

Abstract Despite the success of programmed death ligand 1 (PD-L1) and programmed death 1 (PD-1) blockage as cancer therapies, the overall clinical response rates are still unsatisfying, with only a 25% response rate in most cancers. The underlying mechanisms of non-responsiveness towards anti-PD-L1 treatment have been extensively studied and associated with many factors, including PD1/PD-L1 expression level, tumor mutation burden, IFN signaling, loss of MHC-I, tumor microenvironment (immune infiltration, suppressive immune system), and so on. Immunodeficient mice such as the NSG and NCG are commonly used to study the efficacy of cancer immunotherapies. These mice, reconstituted with either human PBMC or HSC, act as an avatar to provide a window of the potential agent efficacy at the preclinical level. However, due to the challenge of obtaining an HSC/PBMC donor, and often cost and time can also be a limiting factor, many studies only use 2-5 human donors. Here we present data demonstrating the significant variation observed between donor-to-donor, highlighting the importance of testing multiple donors. We reconstituted immune system and tumor tissue humanized mouse models using peripheral blood mononuclear cells (PBMCs), and cell line-derived xenografts (CDX) in severe immunodeficiency NCG mice. Anti-tumor efficacy of anti-PD-L1 (Tecentriq) in huPBMC-NCG mice engrafted with several tumor cells including MDA-MB-231, HCC827, NUGC4, and some other CDX cell lines was tested in our system. In the cases of MDA-MB-231, HCC827, and NUGC4, different donors were enrolled in the same study, and tumor growth inhibition measured by tumor volume (TGITV) of 3% to 52.40% (MDA-MB-231), 5% to 33% (HCC827) and 4.75% to 20.74% (NUGC4) were observed. Especially, In the case of MDA-MB-231, 6 donors were enrolled in this study at the same time. About 40% of immune infiltration was first observed in tumors. High expression of PD1 on immune cells and PDL1 on tumor cells were also detected from different donors simultaneously. Although the similar immune infiltration and PD1/PDL1 expression, the TGITV of 6 donors varied between 3% and 52.40%, suggesting the donor-dependent response to anti-PD-L1 treatment, which is similar to the clinical trials. Our data showed diverse in vivo responses when multiple human PBMC donors were used for preclinical agent evaluation. While unsurprising, it showed the critical need to include various human PBMC donors when an agent is in preclinical status because the donors' immune profile may dictate the study's outcome. This can be divided into two parts, on the one hand, donor screening for favorable efficacy response donors in advance is an alternative approach to ensure the positive efficacy of anti-PDL1 blockade relative therapy. On the other hand, the low-efficacy response donors also can be candidates for anti-PD1/PDL1 combination therapy. Citation Format: Tingting Gu, Weiwei Yu, Hongyan Sun, Fang Zhu, Huiyi Wang, Mengting Wang, Shuai Li, Jianming Xu, Santi Chen, Zhiying Li, Mark Wade Moore, Cunxiang Ju, Hongyu Wang, Jing Zhao, Xiang Gao. Analysis of selective response of anti-PD-L1 treatment in huPBMC-NCG mice reconstituted with different donors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6653.

The cell senescence regulator p16 is a promising cancer prognostic and immune check-point inhibitor (ICI) therapy biomarker.

Cyclin-dependent kinase inhibitor 2A (CDKN2A) encodes the cell senescence regulator protein p16. The expression of p16 raises in cell senescence and has a nuclear regulation in cell aging. Meanwhile, it's also reported to inhibit the aggression of several cancers. But its clinical application and role in cancer immunotherapy needs further investigation. We collected the transcriptional data of pan-cancer and normal human tissues from The Cancer Genome Atlas and the Genotype-Tissue Expression databases. CBioPortal webtool was employed to mine the genomic alteration status of CDKN2A across cancers. Kaplan-Meier method and univariate Cox regression were performed for prognostic assessments across cancers, respectively. Gene Set Enrichment Analysis is the main method used to search the associated cancer hallmarks associated with CDKN2A. TIMER2.0 was used to analyze the immune cell infiltration relevance with CDKN2A in pan-cancer. The associations between CDKN2A and immunotherapy biomarkers or regulators were performed by spearman correlation analysis. We found CDKN2A is overexpressed in most cancers and exhibits prognosis predictive ability in various cancers. In addition, it is significantly correlated with immune-activated hallmarks, cancer immune cell infiltrations and immunoregulators. The most interesting finding is that CDKN2A can significantly predict anti-PDL1 therapy response. Finally, specific inhibitors which correlated with CDKN2A expression in different cancer types were also screened by using Connectivity Map (CMap) tool. The results revealed that CDKN2A acts as a robust cancer prognostic and immunotherapy biomarker. Its function in the regulation of cancer cell senescence might shape the tumor microenvironment and contribute to its predictive ability of immunotherapy.

Abstract P1-04-04: A multiomic approach to the identification of immune signatures of anti-PD1/PDL1 therapy responders in metastatic triple negative breast cancer: new implications in the role of helper T-cell and B-cell interplay

Abstract Introduction Triple negative breast cancer (TNBC) is a heterogeneous breast cancer subtype which continues to portend a particularly poor prognosis compared to other breast cancer subtypes. Immune checkpoint inhibitor (ICI) therapies have emerged as promising options for locally advanced and metastatic TNBC. However, clinical trials have demonstrated mixed results with respect to ICI response. Given varied outcomes and the potential for immune-related adverse events associated with ICIs, there is critical need for identification of accurate biomarkers of response and improved strategies to counteract ICI resistance and/or toxicity. Methods Advanced immunoprofiling of peripheral blood mononuclear cells (PBMCs) and plasma from 7 metastatic TNBC patients with variable responses to anti-PD1 or anti-PDL1 therapy was performed. Samples were analyzed from blood draws obtained: (i) prior to first administration, (ii) while receiving ICI treatment, and (iii) at the time of conformed clinical progression or response to therapy. Response was determined by standard radiological assessment. Immunoprofiling included high parameter flow cytometry, single cell transcriptomics (10x genomics) and secretome analysis (Isoplexis). Single cell RNA profiles from 63,984 cells were analyzed. Results High parameter flow cytometry identified higher circulating levels of a subpopulation of activated CD4+ T cells with a phenotype of CXCR3low CD62Llow CD45RAhigh and CD57high expression in responders versus non-responders. Higher effector function of CD4+ T cells was corroborated by significantly elevated plasma concentrations of IL-2 (p=0.02) and IL-5 (p&amp;lt; 0.0001) among responders. Single cell transcriptomic analysis revealed clusters of B and T cells with distinct activation patterns that were associated with radiographic response. Strikingly, genes involved in B cell activation and T cell-B cell conjugation such as CD81 were found to be highly upregulated among CD4+ T cells from responders. Conclusions Our results are consistent with previous reports describing an association of increased B cell activity in TNBC with improved overall survival. We identified a subpopulation of CD4+ T cells with effector functions consistent with type 2 helper T cells that may not only target cancer cells by direct cytotoxic function, but also promote increased B cell anti-tumor activity. Our study provides insight into specific mechanisms of immune cell interplay that may drive response to ICI therapy. These cell populations and their associated pathways may represent potential biomarkers of response and/or targets for resistance reversal. Citation Format: Avia D. Wilkerson, Patricia A. Rayman, Paul G. Pavicic Jr, Hana Husic, Vladimir Makarov, Ivan Juric, Timothy Chan, Alberto J. Montero, Marcela Diaz-Montero. A multiomic approach to the identification of immune signatures of anti-PD1/PDL1 therapy responders in metastatic triple negative breast cancer: new implications in the role of helper T-cell and B-cell interplay [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-04-04.