PD-1 Antagonist Research Articles

Model-Informed Selection of the Recommended Phase 2 Dosage for Anti-TIGIT Immunotherapy Leveraging co-Expressed PD-1 Inhibitor Target Engagement.

Refining dose projections requires a deep understanding of drug-target relationships at the site of action, which is often challenging to achieve. Here we present a case study of how one can refine dose projections for a TIGIT-targeted immunotherapy by leveraging information from the well-studied PD-1 pathway since the co-expression of PD-1 and TIGIT on immune cells provides a unique opportunity to extrapolate data from one target to inform the dosing strategy for the other. We develop a fit-for-purpose mathematical model that captures the experimentally observed relationship between the concentration of a mouse PD-1 antagonist in the plasma and PD-1 target engagement within the tumor microenvironment (TME). We then assess the applicability of this PD-1 model to elucidate the relationship between drug concentration and target engagement for tiragolumab, an anti-TIGIT antibody, across various doses. This analysis aims to refine our understanding of the dose-response relationship for targeting TIGIT, a critical step in optimizing therapeutic efficacy, without conducting additional experiments. The approach is then extended to project efficacious doses for M6223, another anti-TIGIT antibody, using the established PD-1 model, by leveraging the M6223 clinical PK and PD data, as well as virtual population analysis. This work provides a case study of a possible framework for refining dose projections via quantitative estimation of drug-target relationship at the site of action by leveraging established drug-target relationships. Through extrapolating information from a well-characterized pathway, we offer a method to inform dose optimization strategies with limited data using model-informed drug development.

Abstract P021: Countering adenosine (ADO) in rectal cancer to improve RT responses to immune checkpoint blockade: a trial to test the safety and efficacy of PD1 (AB122) and ADO dual receptor (AB928) antagonists with chemotherapy after short-course RT

Abstract Background: Rectal cancer (RC) is unresponsive to single agent immune checkpoint blockade (ICB), with the exception of microsatellite instability (MSI) high tumors. Neoadjuvant radiotherapy (RT), however, is a standard treatment for locally advanced RC. A recent analysis of RC showed that upregulation of genes reflecting an increased T cell-inflamed and IFN-I response in post-RT samples compared with pre-RT biopsies correlated with pathological responses. The efficacy of combining RT with ICB in RC remains a focus of several ongoing and recently reported clinical trials. Extracellular adenosine (eADO) signaling, an important immunosuppressive pathway in RC, may hinder immune activation as TCGA and our preclinical data, respectively, suggests that eADO generation and signaling is elevated at baseline and exacerbated by RT. In mouse models, the inhibition of eADO generation improved systemic responses to ICB in otherwise refractory tumors. HypothesisWe hypothesize that inhibition of ADO signaling in RC is safe and an effective method to enhance RT-induced anti-tumor T cell responses as a means to sensitize RC to RT and anti-PD1 therapy. Brief Methods: NCT05024097, PANTHER RC trial, is a prospective phase I-II neoadjuvant study in patients with locally advanced RC. Patients receive upfront (wk 1) SC-RT (25 Gy in 5 fx) to the pelvis in combination with the dual A2aR/A2bR (adenosine receptors) inhibitor etrumadenant (AB928). Chemotherapy (wks 3-15), mFOLFOX x 6 cycles, is given with etrumadenant and anti-PD1 antibody zimberelimab (AB122). All patients undergo clinical response assessment (weeks 17-20) followed by watch and wait (if cCR) or total mesorectal excision for pathologic response assessment. The primary endpoint is the proportion of patients who achieve a CR. Secondary endpoints include 3-year disease-related treatment failure and 5-year overall survival. Part I is a modified 3+3 safety run-in for etrumadenant plus SC-RT. Part II is an open label single arm Simon’s 2-stage optimal design. With a sample size of 27 patients (stage 1 = 15 patients and stage 2 = 12 patients) the trial is powered to detect a CR rate of 25% or less versus the atlernative, at least 45%. Results: To date 21 patients have enrolled. One of six patients accrued to part I experienced a grade 3+ treatment related toxicity. A CR was observed in one of five (20%) evaluable patients. In part II, the first eleven of fifteen accrued patients to stage 1 completed treatment and were assessed for response. A CR rate of 82% (4 pCRs, 5 cCRs, 2 pPRs) was observed. The trial is anticipated to proceed to stage 2 and accrue an additional twelve patients (27 total). Conclusion: The preliminary responses are promising and patient enrollment is ongoing. Tumor biopsies, blood specimens, and stool samples before and after RT will be comprehensively analyzed to determine the immune contexture at baseline, during, and after therapy. Correlative studies will help determine whether RT with ADO signaling blockade produces anti-tumor T cells capable of achieving CRs in locally advanced RC. Citation Format: Encouse Golden, Sandra Demaria, Nir Ben Chetrit, Mehraneh Dorna Jafari, Manish Shah, Silvia Formenti.Countering adenosine (ADO) in rectal cancer to improve RT responses to immune checkpoint blockade: a trial to test the safety and efficacy of PD1 (AB122) and ADO dual receptor (AB928) antagonists with chemotherapy after short-course RT.[abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Targeted Therapies in Combination with Radiotherapy; 2025 Jan 26-29; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(2_Suppl):Abstract nr P021

Famitinib plus camrelizumab in patients with advanced colorectal cancer: Data from a multicenter, basket study.

Concurrent inhibition of angiogenesis and immune checkpoints represents a potent therapeutic approach. We conducted a phase 2, multicenter, basket study to assess the efficacy and safety of combination therapy of famitinib (anti-angiogenic agent) plus camrelizumab (PD-1 antagonist) in patients with metastatic solid tumors across 11 cohorts (this study was registered at Clinicaltrials.gov [NCT04346381]). This report focuses on the cohort of patients with metastatic or advanced colorectal cancer. Eligible patients, who had previously received ≥2 lines of systemic treatments for their metastatic disease, were treated with famitinib (20mg once daily) in combination with camrelizumab (200mg intravenously every 3weeks). The primary endpoint was the objective response rate, with secondary endpoints encompassing progression-free survival, overall survival, duration of response, safety and exploratory biomarkers. A total of 44 patients were enrolled and treated. With a median follow-up time of 9.46months (range 2.0-22.5months), objective responses were observed in 6 patients (13.6%; 95% confidence interval [CI], 5.2%-27.4%), all of whom had rectal cancer. The median duration of response is 6.2months (95% CI, 2.3-10.6months). Median progression-free survival was 3.3months (95% CI, 2.1-4.1months), and median overall survival was 10.9months (95% CI, 7.6-15.2months). Among the 44 patients, 29 (65.9%) experienced grade 3 or 4 treatment-related adverse events, predominantly hypertension and proteinuria. In conclusion, the combination of famitinib and camrelizumab demonstrates promising antitumor activity with a manageable safety profile in metastatic colorectal cancer patients. Further research is warranted to confirm and extend these findings.

PD-1 antibody interactions with Fc gamma receptors enable PD-1 agonism to inhibit T cell activation – therapeutic implications for autoimmunity

PD-1 has emerged as a central inhibitory checkpoint receptor in maintaining immune homeostasis and as a target in cancer immunotherapies. However, targeting PD-1 for the treatment of autoimmune diseases has been more challenging. We recently showed in a phase 2a trial that PD-1 could be stimulated with the PD-1 agonist antibody peresolimab to treat rheumatoid arthritis. Here, we demonstrate that PD-1 antibodies can elicit agonism and inhibit T cell activation by co-localization of PD-1 with the T cell receptor via Fcγ receptor (FcγR) engagement. Three PD-1 agonist antibodies with different antigen binding domains, including the clinically validated PD-1 blocking antibody pembrolizumab, suppressed T cell activation to a similar degree; this finding suggests that a specific PD-1-binding epitope is not required for PD-1 agonism. We next explored whether antibody-mediated clustering was an important driver of inhibition of T cell activation; however, we found that a monovalent PD-1 antibody was not inferior to a conventional bivalent antibody in its ability to suppress T cell activation. Importantly, we found that affinity to PD-1 correlated positively with inhibition of T cell activation, with higher affinity antibodies exhibiting higher levels of inhibition. Using a series of human Fc mutants with altered affinities to various FcγRs, we dissected the contributions of FcγRs and found that multiple FcγRs rather than a single receptor contribute to agonist activity. Our work reveals an important role for FcγR binding in the activity of PD-1 antibodies, which has implications for optimizing both PD-1 agonist and antagonist antibodies.

Clinical outcomes in cancer patients with immune checkpoint inhibitor-induced arthritis treated with methotrexate: a retrospective longitudinal monocentric pilot study.

Immune-mediated adverse events (irAEs) from immune checkpoint inhibitors (ICIs) often require high-dose glucocorticoids (GCs), which can promote cancer progression and counteract ICI benefits. This study evaluated the articular and oncologic clinical outcomes of ICI-induced arthritis treated with methotrexate (MTX) as a GC-sparing agent. Adult patients with ICI-induced arthritis in 2023 were included. Arthritis was assessed using the disease activity score on 28 joints by C-reactive protein (DAS28-CRP), with follow-ups every 3 months. All patients received subcutaneous MTX, and oncologic outcomes were evaluated using RECIST 1.1 criteria after one year. Fourteen patients (median age 74.5 years) with melanoma (64.3%), colorectal cancer (14.3%), lung cancer (14.3%), or Hodgkin's lymphoma (7.1%) were treated with PD1 antagonists (92.9%) or combined with CTLA4 blockers (7.1%). Arthritis presentations included oligo-arthritis (36%), mono-arthritis (29%), polyarthritis (21%), and polymyalgia rheumatica-like syndrome (14.3%), with a mean onset of 4.7±3.7 months post-ICI. MTX was started for all at a mean dose of 9.5±1.5 mg weekly, beginning at the first rheumatology visit in 78.5% of patients. Over a mean follow-up of 12.8±4.6 months, DAS28-CRP scores improved significantly, and prednisone dosage was in all reduced (3.6 mg at V4 vs. 8.4 mg at V0, p=0.003). No major MTX-related toxicities were noted. Cancer responses at follow-up were complete (50%), partial (21.4%), stable disease (7.1%), and progression (21.5%). The use of MTX in ICI-induced arthritis showed promising results in reducing GC dosages and managing the inflammatory articular activity, with no major toxicities observed over one year. These findings suggest that MTX may be a viable GC-sparing option in this context, but larger, controlled studies are needed to confirm these observations and better understand the impact on both articular and oncologic outcomes.

Abstract 5300: BH3120, PD-L1 X 4-1BB bispecific antibody, plus PD-1 antagonist results in synergistic anti-tumor efficacy with excellent safety profile

Abstract BH3120 is a clinical stage PD-L1 binding dependent 4-1BB agonist with moderate affinity against 4-1BB. In multiple preclinical evaluations, BH3120 decoupled T cell modulation in TME from that in normal tissues, indicating potential decoupling of efficacy from safety concerns. 4-1BB agonism improves T cell functions in TME, combining BH3120 and PD-1 antagonist shows dose dependent and complete control of established tumor burden with bi-directionally synergistic mechanism: Blockade of PD-1 increases the expression and exposure of surface PD-L1, providing BH3120 more chance to form immune clusters in the tumor environment. In the meantime, increased PD-1 induced by BH3120 can be blocked by PD-1 antagonist. This bi-directional mechanism results in rapid eradication of tumor tissues shortening the time to regression, indicating potentially fast control of tumor burden and associated symptoms. With the characteristics decoupling co-stimulatory activity in TME from that in normal tissues, BH3120 either as a monotherapy or in combination with PD-1 antagonist was not associated with liver toxicity and other concerns in relation to excessive modulation of immune cells systemically. Safety profile and clinical signs with BH3120 are being investigated in early-stage clinical trials as a monotherapy and in combination with a PD-1 antagonist. Citation Format: Jun Wang, Jing Wang, Yang Liu, Jiangcheng Xu, Jiawang Liu, Kyoungwoo Lee. BH3120, PD-L1 X 4-1BB bispecific antibody, plus PD-1 antagonist results in synergistic anti-tumor efficacy with excellent safety profile [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5300.

Abstract 2651: A selective HPK1 inhibitor FB849 reprograms intratumoral immune cells and elicits strong anti-cancer immunity

Abstract Hematopoietic progenitor kinase 1 (HPK1) is a negative regulator of immune cells and suppresses the immune function of a wide range of cells, including T cells, B cells, and dendritic cells (DCs). Recent studies have shown that HPK1 is correlated with increased T cell exhaustion, one of hallmark phenomena for acquired resistance to immune checkpoint inhibitors (ICIs), that is a major obstacle in the current immunotherapy regimen with an increasing need of novel agent to overcome it. We have discovered FB849, a highly potent, highly selective, and orally available HPK1 inhibitor especially with an excellent selectivity over key immune-related off target kinases. FB849 confers the activation of various human primary immune cells such as T cells, B cells, and DCs in vitro. FB849 elicited robust anti-cancer efficacy in syngeneic mouse models including MC38 and CT26 both as a monotherapy and in combination with a PD-1 antagonist. A dramatic synergistic efficacy with FB849 and PD-1 combination was observed in EMT6. Durable effects possibly through immunological memory were also confirmed in CT26. Under a CD8+ T cell depletion condition in vivo, FB849 still maintained monotherapy efficacy, demonstrating its anti-cancer immunity through CD8+ T cell-independent pathway possibly via efficacy through myeloid lineage. FB849 significantly reduced the LAG3+ and PD-1+ exhausted T cells and CD25+ FoxP3+ regulatory T cells, simultaneously depleted tumor associated macrophages (TAMs), and modulated dendritic cell population in the syngeneic tumors. To better understand how FB849’s effects on human cancer, FB849 was evaluated in isolated TILs (tumor-infiltrating lymphocytes) from patients with renal cell carcinoma and other cancer types. CD8+ T cells from a RCC patient was highly activated evidenced by the increased cell proliferation and the enhanced cytokine secretion by ex vivo treatment of FB849 alone or by the combination with PD-1 antagonist. Similar phenomena were observed in gastric cancer, hepatocellular carcinoma, colorectal cancer, and head and neck cancer. FB849 treatment resulted in the activation of not only stem-like T cells but also in the partial reinvigoration of terminally differentiated T cells from a RCC patient. These data from patient TIL’s together with mouse TIL’s pinpoint unprecedented anti-tumor mechanism by FB849 through modulation of exhausted T cells as well as myeloid cells. Altogether, this study supports the planned clinical development of FB849 as a promising immuno-oncology agent as a monotherapy in the selected cancer types and as post-ICI combination with a PD-1 antagonist. Citation Format: Hyekyoung Kim, Seungmook Lim, A Yeong Park, Jinhwa Lee, Jamie Jae Eun Kim, Seung Hyuck Jeon, Yong Joon Lee, Eui-Cheol Shin, Seongkon Kim. A selective HPK1 inhibitor FB849 reprograms intratumoral immune cells and elicits strong anti-cancer immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2651.

Abstract 2379: The bispecific antibody KA-3007 against B7H3 and CD28 enhances T cell activation in solid tumors

Abstract Immunotherapy, revolutionizing the treatment of advanced solid tumors by blocking PD1 signaling, faces challenges as most cancers remain unresponsive to anti-PD-1 therapy. CD28, a key immune co-stimulatory receptor on T cells, often lacks ligands expressed on tumor cells. B7H3 is highly expressed in various solid tumors. In this study, we developed a bispecific antibody (BsAb) named KA-3007, targeting B7H3 and human CD28 to activate T cells in the tumor microenvironment. KA-3007, featuring an identical light chain, was developed using our common light chain bispecific antibody discovery platform with knob-into-hole technology. This BsAb is in regular IgG1 format with mutations in the Fc domain to eliminate ADCC, ADCP, and CDC activity. Its two Fabs bind to B7H3 with high affinity and CD28 with relatively low affinity. Co-culturing T cells with tumor cells expressing B7H3 enhances T cell activation. In PBMC humanized immunodeficient mouse tumor models, KA-3007 effectively suppresses the growth of NCI-H292 tumors, with or without a PD1 antagonist antibody. Furthermore, this antibody exhibits a half-life of more than five days in the blood of Balb/c mice. Finally, we assessed the developability of KA-3007 with different treatments such as high concentration, low pH, repeated freezing and thawing, and high temperature, and it shows neither aggregation nor degradation. In conclusion, the BsAb KA-3007, developed with our common light chain antibody discovery platform, emerges as a promising pre-clinical candidate drug for the treatment of solid cancers. Citation Format: Guojin Wu, Zhengcheng Guo, Hao Peng, Feng Hao, Feng He, Jinying Ning. The bispecific antibody KA-3007 against B7H3 and CD28 enhances T cell activation in solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2379.

Abstract 2378: The triple-specific antibody KA-3003, targeting PSMA, CD28, and 4-1BB, is developed for the treatment of prostate cancer by enhancing T cell activity within the tumor

Abstract Immunotherapy, revolutionizing the treatment of advanced solid tumors by blocking PD1 signaling, has encountered a challenge in prostate cancer, exhibiting a low response ratio to anti-PD-1 therapy. Furthermore, cancer immunotherapy using 4-1BB agonists faces limited clinical development due to dose-limiting toxicity. Here, we developed a tri-specific antibody, KA-3003, targeting PSMA, CD28, and 4-1BB, with the goal of enhancing T cell activation in the tumor microenvironment. This antibody was created using our common light chain bispecific antibody discovery platform and nanobody antibody discovery platform with knob-into-hole technology. KA-3003, in IgG1 format, features mutations in the Fc domain to eliminate ADCC, ADCP, and CDC activity. It contains two identical nanobodies at the C-terminal against 4-1BB, while binding to PSMA and CD28 with two Fabs at the N-terminal, sharing an identical light chain. KA-3003 exhibits high affinity for PSMA and relatively lower affinity for CD28 and CD137. In the presence of a low concentration of CD3 antibody to stimulate T cell activation, co-culture of tumor cells expressing PSMA with primary T cells isolated from human PBMC enhances T cell activation and proliferation. In PBMC humanized immunodeficient mouse tumor models, KA-3003 effectively suppresses the growth of 22Rv1 tumors with or without a PD1 antagonist antibody. Additionally, KA-3003 has a half-life of more than five days in the blood of Balb/c mice. Finally, we assessed the developability of this antibody with different treatments such as high concentration, low pH, repeated freezing and thawing, and high temperature. KA-3003 shows neither aggregation nor degradation. In conclusion, the tri-specific antibody KA-3003, developed with our common light chain antibody discovery platform, stands out as a promising pre-clinical candidate drug for the treatment of prostate cancer. Citation Format: Guojin Wu, Zhengcheng Guo, Hao Peng, Feng Hao, Tongtong Liu, Jinying Ning. The triple-specific antibody KA-3003, targeting PSMA, CD28, and 4-1BB, is developed for the treatment of prostate cancer by enhancing T cell activity within the tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2378.

Abstract 1367: PD1 signaling uncovers a pathogenic subset of cytotoxic T cells

Abstract PD-1 drives its fame for serving as a pivotal immune checkpoint receptor on T cells. Within the realm of cancer immunotherapy, blocking this receptor triggers the T cell activation, leading to the immune response against tumors. Conversely, in autoimmunity, PD-1 agonist is a prime candidate for effectively suppressing the T-cell-driven auto-reactivity and self-tissue damage. Despite a decade of exploration and unlike cancer immunotherapy, the efficacy of PD-1 agonists in treating autoimmunity remains a challenge. To overcome this hurdle, innovative methods must be devised to look beyond the PD-1 receptor engagement and uncover the downstream effectors involved in PD-1 signal transduction. A comprehensive genome-wide CRISPR/Cas9 screen was also conducted to pinpoint genes linked to PD-1 signaling. An in-depth exploration of genes associated with PD-1 signaling was undertaken, utilizing publicly accessible bulk and single-cell RNA sequencing datasets of patients with melanoma treated with PD-1 blockade and in patients with inflammatory arthritis. We employed flow cytometry of T cells derived from peripheral blood and synovial fluid to validate the results.Our screening process validated established regulators in the proximal PD-1 signaling pathway and unveiled an additional 1,112 unique genes associated with PD-1's capacity to hinder T-cell functions. These genes demonstrated a robust correlation with the response of cancer patients to PD-1 blockades and exhibited high scores for tumor immune dysfunction and exclusion, affirming their downstream involvement in PD-1 signaling. Functional annotation underscored the significance of these genes in established immune regulation processes. Intriguingly, T cells isolated from patients with inflammatory arthritis exhibited a significant downregulation of the same genes, emphasizing their overarching inhibitory role. Examining single-cell RNA sequencing data revealed that five specific genes, KLRG1, CRTAM, SLAMF7, PTPN2, and KLRD1, were notably downregulated in activated and effector T cells from synovial fluids. Back-gating these genes to canonical cytotoxic T cell signatures identified PD-1+ HLA-DRHIGH KLRGLOW T cells as a novel inflammatory T cell subset that should be targeted with immunotherapies. Our findings suggest that PD-1+ HLA-DRHIGH KLRGLOW T cells are promising targets for prospective PD-1 antagonists and agonists in treating inflammatory diseases. This study not only reveals novel genes linked to PD-1 downstream functions but also serves as a valuable resource, offering insights for further investigations essential to delineate the role of PD-1 within immune responses. Citation Format: Shoiab Bukhari, Shalom Lerrer, Johanna Straube, Robert Winchester, Brian Henick, Matthew Dragovich, Adam Mor. PD1 signaling uncovers a pathogenic subset of cytotoxic T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1367.

Abstract 2381: The bispecific antibody KA-3001, targeting PSMA and CD28, specifically enhances T cell activation within prostate tumors

Abstract Immunotherapy, which involves blocking PD-1 signaling, has revolutionized the treatment paradigm for advanced solid tumors. However, prostate cancer exhibits a low response ratio to anti-PD-1 therapy. In this study, we have developed a bispecific antibody (BsAb), KA-3001, targeting PSMA and human CD28, aiming to enhance T cell activation in the tumor microenvironment. KA-3001, in a regular IgG1 format, features an identical light chain and was designed using our common light chain bispecific antibody discovery platform with knob-into-hole technology. Mutations in the Fc domain were introduced to eliminate ADCC, ADCP, and CDC activity. KA-3001's two Fabs demonstrate high affinity for PSMA and relatively low affinity for CD28. In comparison to REGN5678, KA-3001 exhibits significantly stronger binding to PSMA-expressing prostate tumor cells, along with relatively lower CD28 activation, minimizing toxicity while maintaining anti-tumor efficacy. In PBMC humanized immunodeficient mouse tumor models, KA-3001 effectively suppresses the growth of 22Rv1 tumors with or without PD-1 antagonist antibody. Furthermore, KA-3001 has a half-life of more than five days in the blood of Balb/c mice. Finally, we assessed the developability of this antibody through various treatments such as high concentration, low pH, repeated freezing and thawing, and high temperature. The BsAb demonstrates neither aggregation nor degradation. In conclusion, the BsAb KA-3001, developed using our common light chain antibody discovery platform, stands out as a promising pre-clinical candidate drug for the treatment of prostate cancer. Citation Format: Jiabei Liang, Chen Su, Hao Peng, Feng Hao, Tongtong Liu, Jinying Ning, Guojin Wu. The bispecific antibody KA-3001, targeting PSMA and CD28, specifically enhances T cell activation within prostate tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2381.

Safety, Efficacy and T-Cell Predictive Biomarkers in a Phase I Trial of Copanlisib+Nivolumab in Patients with Richter's Transformation (RT) or Transformed Non-Hodgkin Lymphoma (tNHL)

Background. Despite advances in targeted and cellular therapy, outcomes among patients (pts) with RT and tNHL remain dismal. Copanlisib (COPA) is a selective, small molecule, PI3Kinhibitor which preferentially targets the p110αδ isoforms . COPA has shown clinical efficacy in NHL and is an approved therapy for follicular lymphoma (FL). Nivolumab (NIVO) is a PD-1 antagonist which has demonstrated activity in NHL. Furthermore, combined targeting of PI3K and PD-1 has demonstrated synergy in pre-clinical lymphoma models. Here we report results of a phase 1 study of COPA in combination with NIVO in pts with R/R RT or tNHL (NCT03884998) and correlate response to treatment and T cell functionality in RT. Methods. This ongoing multicenter, open-label, phase I, investigator-sponsored study is enrolling pts with RT or tNHL, age ≥18 years, whose disease has relapsed or was refractory to ≥1 prior line of therapy. The phase I portion of the study follows a standard 3+3 design, followed by a dose expansion of 16 evaluable pts, with two planned dose levels of COPA administered IV (dose level [DL]1 - 45 mg on days 1, 8 and 15 and DL2 - 60 mg on days 1, 8 and 15 of a 28-day cycle). NIVO 240 mg is given IV on days 1 and 15. Pts receive up to 24 cycles of therapy. Dose limiting toxicities (DLT) were defined as grade ≥4 hematologic lasting > 7 days or grade ≥3 non-hematologic toxicities. The primary study objective is to evaluate the maximum tolerated dose (MTD) of the combination; secondary objectives are preliminary efficacy by Lugano criteria. Exploratory objectives include T-cell functionality assessed by flow cytometry analysis of cell subsets as well as scRNA-Seq performed on biospecimens banked from pts pre-treatment, after cycles 1 and 5, and at the end of treatment. Results. The study enrolled 25 pts to date, 11 in dose finding (8 at DL1 and 3 at DL2) and 14 in dose expansion cohorts. Fourteen pts had RT and 11 had tNHL (10 tFL and 1 transformed lymphoplasmacytic lymphoma). Median (med) age was 65 years (32-77), 88% (22/25) had ECOG performance status 0-1. Pts had received a med of 4 prior lines of therapy (range, 1-10); 8 pts (2 RT, 6 tNHL) had CAR T cells. During dose finding, 8 pts were treated at DL1 (45 mg COPA), of which 2 pts did not complete the DLT period due to rapidly progressive disease and were replaced. No DLTs were observed in 6 evaluable pts at DL1. At DL2 (60 mg COPA), three DLTs (neutropenia, thrombocytopenia) occurred in 2 pts determining the MTD of COPA to be 45 mg. After a median follow-up of 14 months (range 1.8-20.6), the most common treatment-related adverse events (AEs, any grade) were diarrhea and anemia (Table 1). Twenty-three pts went off protocol after a med of 3 cycles (range 1-20); 2 remain on treatment. Sixteen pts discontinued therapy due to progressive disease and 6 due to AEs. Among the 23 efficacy-evaluable pts who completed at least one cycle of therapy, 10 pts achieved a response (ORR 43%). Pts with tFL had an ORR of 60% (2 CR and 4 PR) with median progression free survival (mPFS) 4.8 months (95%CI: 0.4-16.8) and median duration of response (mDOR) 10.2 months (95%CI: 2.0-13.6) (Figure 1). Pts with RT had an ORR of 33% (2 CR and 2 PR) with mPFS 2.0 months (95%CI: 0.7-4.9) and mDOR not reached (95%CI: 3.0-NA). Analysis of paired samples from pts using flow cytometry and scRNA-Seq demonstrated an increase in circulating CD8+ T cell population and a decrease in exhaustion markers (PD1, CTLA-4) after exposure to COPA/NIVO. Analysis of 2 responding RT pts by scRNA-Seq demonstrated downregulation of MYC in tumor cells and upregulation of IFN response in T cells. This pattern was not observed 3 RT non-responders (NRs). By contrast, CD8+ effector T-cells from NRs exhibited downmodulation of the IFN response after cycle 1 of treatment and concurrent activation of p53-regulated genes and apoptotic genes. Tregs sourced from RT responders showed enhanced expression of apoptosis pathways after treatment, while these pathways were downregulated in NR Tregs. Discussion. We identified COPA 45 mg IV on days 1, 8 and 15 as the MTD/RP2D in combination with NIVO in pts with R/R RT and tFL. This combination was generally well-tolerated and had activity, particularly in pts with with tFL. We observed key differences in gene expression patterns in T cell subsets between the responders and NRs. Downregulation of MYC in the tumor, activation of the apoptotic program in Tregs and enhanced CD8 T-cell IFN response were associated with treatment response in RT. Accrual is ongoing.

Pathogenic/Likely Pathogenic Somatic CDK12 Mutations in Black Men With Prostate Cancer.

Considering recently published data, this letter to the editor highlights the clinical relevance of CDK12 pathogenic or likely pathogenic mutations, noting that Black men have prostate cancers with increased rates of this pathologic alteration. Practitioners should be made aware of recent findings, given that CDK12 mutations are known to be associated with aggressive variants of prostate cancer and that they may confer susceptibility to PD-1 antagonists.

A platform trial of neoadjuvant and adjuvant antitumor vaccination alone or in combination with PD-1 antagonist and CD137 agonist antibodies in patients with resectable pancreatic adenocarcinoma

A neoadjuvant immunotherapy platform clinical trial allows for rapid evaluation of treatment-related changes in tumors and identifying targets to optimize treatment responses. We enrolled patients with resectable pancreatic adenocarcinoma into such a platform trial (NCT02451982) to receive pancreatic cancer GVAX vaccine with low-dose cyclophosphamide alone (Arm A; n = 16), with anti-PD-1 antibody nivolumab (Arm B; n = 14), and with both nivolumab and anti-CD137 agonist antibody urelumab (Arm C; n = 10), respectively. The primary endpoint for Arms A/B - treatment-related change in IL17A expression in vaccine-induced lymphoid aggregates - was previously published. Here, we report the primary endpoint for Arms B/C: treatment-related change in intratumoral CD8+ CD137+ cells and the secondary outcomes including safety, disease-free and overall survivals for all Arms. Treatment with GVAX+nivolumab+urelumab meets the primary endpoint by significantly increasing intratumoral CD8+ CD137+ cells (p = 0.003) compared to GVAX+Nivolumab. All treatments are well-tolerated. Median disease-free and overall survivals, respectively, are 13.90/14.98/33.51 and 23.59/27.01/35.55 months for Arms A/B/C. GVAX+nivolumab+urelumab demonstrates numerically-improved disease-free survival (HR = 0.55, p = 0.242; HR = 0.51, p = 0.173) and overall survival (HR = 0.59, p = 0.377; HR = 0.53, p = 0.279) compared to GVAX and GVAX+nivolumab, respectively, although not statistically significant due to small sample size. Therefore, neoadjuvant and adjuvant GVAX with PD-1 blockade and CD137 agonist antibody therapy is safe, increases intratumoral activated, cytotoxic T cells, and demonstrates a potentially promising efficacy signal in resectable pancreatic adenocarcinoma that warrants further study.

Phase II study of the efficacy of retifanlimab (Rf) (INCMGA00012) in penile squamous cell carcinoma (PSqCC): ORPHEUS final analysis.

5043 Background: PSqCC is a rare tumor with poor prognosis. The standard of care for advanced disease (AD) has been palliative platinum-based chemotherapy (CT). Most PSqCC patients (pts) have high levels of programmed death-ligand 1 (PD-L1). ORPHEUS has evaluated the efficacy and safety of Rf –a PD-1 antagonist– in pts with unresectable locally advanced or metastatic PSqCC. Methods: ORPHEUS (NCT04231981) is an international, multicenter, open-label, single-arm phase II trial. The study enrolled pts aged ≥18 years with locally advanced or metastatic PSqCC who had not received any previous treatment with PD-1 or PD-L1/2 agents. Pts received Rf 500 mg intravenously on day 1 of each 28-day cycle until progressive disease, unacceptable toxicity, discontinuation or death. The primary endpoint was investigator-assessed objective response rate (ORR) as per RECIST v.1.1. Secondary endpoints included clinical benefit rate, progression-free survival (PFS), duration of response (DoR), time to response (TTR), disease control rate (DCR), overall survival (OS) and safety evaluated as per NCI-CTCAE 5.0. The design was planned to attain an 80% power at 5% one-sided α level (H0: ORR≤5%; HA: ORR≥25%). Results: Between Jul 7, 2020, and Aug 26, 2021, 18 men were enrolled at 8 sites from Italy and Spain. Median age was 64.2 years (range 42-81),13 (72.2%) pts had an AD at first diagnosis, 15 (83.3%) had a previous surgical procedure for penile cancer (lymphadenectomy in 7 pts), 10 (55.6%) had previously received platinum-based CT (TPF/TIP in 8 pts) and 7 (38.9%) were naïve to AD treatment. At data cutoff (Aug 26, 2022), with a median follow-up of 7.2 months, no pts remained on therapy. ORR (3 partial responses) was 16.7% (95% CI 5.8%-39.2%) with a median DoR and TTR of 3.3 (range 1.8-8.5) and 1.9 (range 1.7-2.4) months, respectively. DCR was (33.3%) (1 stable disease ≥ 6 months). Median PFS was 2.0 months (95% CI 1.6-3.3) and median OS with 17 events was 7.2 months (95% CI 3.0-9.8). Most common non-hematological treatment emergent adverse events (TEAEs) of any grade (G) were fatigue (27.8%; 5.6% G≥3), cellulitis, groin infection and Pseudomonas infection (11.1%; 5.6% G≥3), respectively. Treatment related (TR) TEAEs were fatigue (22.2%; 5.6% G≥3), rash (5.6%; 0% G≥3) and decreased appetite (5.6% G≥3). Anemia (11.1%; 0% G≥3) was the most frequent hematological TEAE. Serious unrelated TEAEs occurred in 5 pts (27.8%). Two (11.1%) pts discontinued treatment due to unrelated non-hematological TEAEs; 1 case of infected lymphocele (G3) and 1 case of skin neoplasm bleeding (G3). No TR deaths were reported. Conclusions: Rf in monotherapy showed signals of clinical activity in advanced or metastatic PSqCC pts. Safety profile was consistent with previous data. These results along with identification of suitable biomarkers could help to develop novel immunotherapy combination strategies in this orphan genitourinary tumor. Clinical trial information: NCT04231981 .

Combination therapy with PD-1 inhibition plus rapamycin and metformin enhances anti-tumor efficacy in triple negative breast cancer

Immunotherapy using PD-1/PD-L1 inhibitors has been proved to be effective in triple negative breast cancer (TNBC), albeit only in a fraction of patients. Emerging evidences indicate mTOR blockade and metformin may re-orchestrate the immune system in tumors. Herein, in this study we aimed to evaluate the anti-tumor efficacy of PD-1 monoclonal antibody with mTOR inhibitor rapamycin or with the anti-diabetic drug metformin. The status of PD-1/PD-L1 and mTOR pathway was determined through analyzing the TCGA and CCLE data in TNBCs as well as by detection at mRNA and protein level. The inhibition of tumor growth and metastasis by anti-PD-1 combined with rapamycin or with metformin was evaluated in allograft mouse model of TNBC. The effects of combination therapy on the AMPK, mTOR and PD-1/PD-L1 pathways were also evaluated. The combination treatment with PD-1 McAb and rapamycin/metformin had additive effects on suppression of tumor growth and distant metastasis in mice. Compared with the control group and the monotherapy, combined PD-1 McAb with either rapamycin or metformin exhibited more obvious effects on induction of necrosis, CD8+ T lymphocytes infiltrating and inhibition of PD-L1 expression in TNBC homograft. In vitro study showed either rapamycin or metformin not only decreased PD-L1 expression, but increased p-AMPK expression and therefore led to down-regulation of p-S6. In summary, combination of PD-1 antagonist with either rapamycin or metformin led to more infiltrating TILs and decreased PD-L1 resulting in enhanced antitumor immunity and blockade of PD-1/PD-L1 pathway. Our results suggested such combination therapy may be a potential therapeutic strategy for TNBC patients.

NL-201 Upregulates MHC-I Expression and Intratumoral T-cell Receptor Diversity, and Demonstrates Robust Antitumor Activity as Monotherapy and in Combination with PD-1 Blockade.

Cytokine engineering has shown promise as a means to create novel immunomodulatory agents or to improve upon the therapeutic potential of natural cytokines. NL-201, a de novo, hyperstable, IL2 receptor alpha (IL2Rα)-independent agonist of the receptors for IL2 and IL15, elicits robust preclinical activity in syngeneic murine cancer models, including those resistant to immune checkpoint inhibitors (ICI). Here, we report that NL-201 monotherapy converts 'cold' tumor microenvironments (TME) to immunologically 'hot' states by driving pro-inflammatory gene expression, enhancing IFNγ-dependent MHC-I expression, and expanding both T-cell number and clonal diversity. In addition, the combination of NL-201 and anti-PD-1 resulted in complementary antitumor activity in the immunologically 'cold' and ICI resistant B16F10, EMT6, and Renca syngeneic models. In the B16F10 model, treatment with NL-201 plus anti-PD-1 increased the abundance of CD4+ and CD8+ effector T cells in the TME. These findings reveal an important mechanistic basis for the antitumor activity of NL-201 both as a monotherapy and in combination with PD-1 antagonists, and provide further context for the role of IL2Rα-based signaling in ICI-resistant tumors.

Abstract 1799: BH3120, a bispecific antibody targeting 4-1BB and PD-L1 simultaneously, stimulates T cells in tumor tissue preferred manner

Abstract BH3120 is a heterodimeric bispecific antibody, designed to target 4-1BB and PD-L1 simultaneously with Pentambody™ platform, to stimulate anti-tumor immune response in a tumor microenvironment (TME) specific manner. BH3120 showed strong antitumor efficacy in multiple tumor models, and combination of BH3120 with a PD-1 antagonist showed synergic effects eradicating tumor. While BH3120 consistently activates T cells, both as a monotherapy and in combination with a PD-1 antagonist, modulation of immune system in the tumor tissue is clearly de-coupled from that in peripheral blood, suggesting reduced risks of immune related adverse events (irAEs) with BH3120. To verify this hypothesis, BH3120 was compared with reference bispecific antibodies. Combination of BH3120 with a PD-1 antogonist does not result in elevation of transaminase enzymes, while the reference bispecific antibodies, when combined with the same PD-1 antagonist, show significant increase of the enzymes and macrophage in liver. In the toxicology studies conducted so far with cynomolgus monkeys, NOAEL of BH3120 was determined to be 200 mg/kg (QW X 5). Citation Format: Jing Wang, Jun Wang, Yang Liu, Yan Pang, Aihong Zhang, Jie Feng, Aibo Sun, Xiao Ma, Jingmei Cai, Jiangcheng Xu, Jiawang Liu, Kyoungwoo Lee. BH3120, a bispecific antibody targeting 4-1BB and PD-L1 simultaneously, stimulates T cells in tumor tissue preferred manner [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 1799.

Abstract 5134: PD-1/PD-L1 signalling axis, “a double-edged sword” in DSS induced colitis mouse model

Abstract Background. Immune checkpoint molecules are essential for modulating immune responses and maintaining self-tolerance. While immune checkpoint inhibitors have improved the treatment of a broad spectrum of cancers, many of them are also believed to play a critical role in the induction of immune related adverse events (irAEs) such as autoimmune and inflammatory diseases. For example, patients receiving anti-PD-1 based therapy frequently develop colitis. In addition, dysfunctional PD-1 signalling has also been linked to increasing susceptibility to autoimmune and inflammatory diseases. Therefore, immune checkpoint molecule agonist which could, like their natural ligands, confer a great potential in suppressing excessively activated immune response observed in autoimmune and inflammatory diseases. Methods. In the first part, the proinflammation effects of a Pembrolizumab analogue was evaluated in a MC38-OVA colorectal tumor bearing mice treated with or without DSS. In the second part, an anti-hPD-1 agonistic antibody at 10 mg/kg was evaluated in acute DSS IBD model. Results. In the MC38-OVA colorectal cancer model, mice treated with Pembrolizumab analogue only or Pembrolizumab analogue plus 1.5% DSS showed significant tumor growth inhibition (100% TGI and 92.01% TGI, respectively at Day 27) compared to their respective control group, which suggests this Pembrolizumab analogue induced robust anti-tumor immunity against MC38-OVA tumors. Notably, 8/8 mice treated with Pembrolizumab analogue only showed complete tumor regression, while only 5/8 mice treated with Pembrolizumab analogue plus DSS showed complete tumor regression. Taken together, these results suggest DSS treatment leading to a proinflammatory context could compromise anti-hPD-1 anti-tumor efficacy. Moreover, mice treated with Pembrolizumab analogue plus DSS also showed 3.59% more Body Weight Loss (BWL) in comparison to 1.5% DSS only group, suggesting that Pembrolizumab analogue could exacerbate DSS induced colitis. In the acute DSS IBD model, mice treated with an agonistic anti-hPD-1 antibody showed significantly lower disease score (DAI 5.3 vs DAI 2.4) and less BWL (BWL 13.44% vs BWL 3.31%) in comparison to isotype control group. In addition, pathology results showed that mice treated with agonistic anti-hPD-1 exhibits significantly less inflammatory cell infiltration and colonic lesions when compared to isotype control group. Conclusion. In summary, we reported in this study that blocking of PD-L1/PD-1 signalling axis by a PD-1 antagonist activated T cell function which at the same time aggravated DSS induced colitis in mouse. In contrast, activation of PD-L1/PD-1 signalling pathway by a PD-1 agonist alleviated DSS induced colitis. Citation Format: Tao Yang, Rongfei Lu, kaixia lian, Likun Zhang, Dawei Wang, Xinhe Feng, Xiaoyu An, Jessie (Jingjing) Wang, Carl K. Edwards. PD-1/PD-L1 signalling axis, “a double-edged sword” in DSS induced colitis mouse model. [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 5134.

Phase II study (daNIS-1) of the anti–TGF-β monoclonal antibody (mAb) NIS793 with and without the PD-1 inhibitor spartalizumab in combination with nab-paclitaxel/gemcitabine (NG) versus NG alone in patients (pts) with first-line metastatic pancreatic ductal adenocarcinoma (mPDAC).

TPS761 Background: Overall survival remains short for pts with mPDAC despite approved therapies, highlighting the need for more effective treatment options. While TGF-β can act as a tumor suppressor in normal tissue and early-stage PDAC, it is associated with tumorigenic processes (such as enhanced genomic instability, neoangiogenesis, epithelial-to-mesenchymal transition, and metastasis) observed in late-stage PDAC. Within the pancreatic tumor microenvironment (TME), TGF-β activates stellate cells and cancer-associated fibroblasts, thereby promoting fibrotic network development and immune exclusion, maintaining an immunosuppressive TME. Preclinical data in murine models have shown that addition of TGF-β blockade to anti-PD-1 therapy or NG augmented the antitumor activity of those agents, leading to tumor regression. These data provide the rationale for combining TGF-β-targeting agents with chemotherapy and/or immunotherapy. This study investigates NIS793, a human IgG2 mAb that binds TGF-β1 and 2, with and without spartalizumab (PD-1 antagonist) combined with NG in treatment-naïve mPDAC. Methods: This is a phase II open-label, randomized study (NCT04390763) with a safety run-in period followed by randomization. Eligible pts are adults with previously untreated mPDAC with measurable disease as per RECIST 1.1 and ECOG performance status score ≤1. Pts are excluded if they have a microsatellite-unstable tumor. The safety run-in was completed and confirmed a dose of NIS793 (intravenously [IV] 2100 mg Q2W) + spartalizumab (IV 400 mg Q4W) + nab-paclitaxel (IV 125 mg/m2 on Days 1, 8, and 15) + gemcitabine (IV 1000 mg/m2 on Days 1, 8, and 15). In the randomized part, pts will be randomized 1:1:1 to NIS793 + spartalizumab + NG (n = 50) or NIS793 + NG (n = 50) or NG (n = 50). Treatment will continue until disease progression, unacceptable toxicity, discontinuation by investigator’s/pt’s choice, or withdrawal of consent. The primary objective is to evaluate the progression-free survival per RECIST v1.1 of NIS793 + NG with or without spartalizumab, versus NG alone. Secondary objectives include safety and tolerability, antitumor activity, overall survival, change in tumoral CD8 and PD-L1 status, and characterization of immunogenicity and pharmacokinetics. Efficacy will be assessed by investigator per RECIST v1.1 and iRECIST at screening, every 8 weeks for 1 year and then every 12 weeks until disease progression. The study is ongoing and has an estimated enrollment of 161 pts. There are currently 31 sites participating across 14 countries. The study is funded by Novartis. Clinical trial information: NCT04390763 .