scholarly journals Preliminary evidence of antitumour activity of Ipatasertib (Ipat) and Atezolizumab (ATZ) in glioblastoma patients (pts) with PTEN loss from the Phase 1 Ice-CAP trial (NCT03673787)

2021 ◽  
Vol 23 (Supplement_4) ◽  
pp. iv10-iv10
Author(s):  
Crescens Tiu ◽  
Liam Welsh ◽  
Timothy Jones ◽  
Anna Zachariou ◽  
Toby Prout ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Checkpoint Inhibitors ◽  
Tumour Resection ◽  
Clinical Activity ◽  
Who Grade ◽  
Pten Loss ◽  
Ice Cap ◽  
Post Surgery ◽  
Expansion Cohort

Abstract Aims Despite improved understanding of effector T-cell trafficking into the central nervous system, initial trials with anti-PD1/PD-L1 immune checkpoint inhibitors (ICIs) have failed to meet their primary endpoints. PTEN loss of function is frequent in GBM and has been correlated with not only poor overall prognosis, but also impaired antitumour responses, including reduced T cell infiltration into tumour and reduced efficacy of ICIs. Ipatasertib is a novel, potent, selective, small-molecule inhibitor of Akt. We have shown that Ipatasertib efficiently depletes FOXP3+ regulatory T cells from the tumour microenvironment (TME) resulting in increased infiltration of effector T cells in solid tumours (Lopez 2020, AACR). We hypothesize that the use of AKT inhibition in PTEN glioblastomas may deplete the TME of suppressive immune cells, and render malignant brain tumours more responsive to ICIs. We present updated data for the combination of Ipat+ATZ in patients with glioblastoma. Method Patients with relapsed WHO grade IV GBM with stable neurological symptoms ≥5 days prior to enrolment, requiring <3mg Dexamethasone were recruited into two cohorts of this early phase, open-label, single-centre trial studying the combination of Ipatasertib (Ipat) and Atezolizumab (ATZ): a dose finding cohort (A2; n=9) and an expansion cohort (B3; n=7, recruitment ongoing). The Ice-CAP A2 cohort assessed safety, pharmacodynamic, and preliminary clinical activity of Ipat (200mg or 400mg OD) + ATZ (1200mg Q3W) in pts with potentially resectable relapsed WHO Grade IV GBM. Pts had a 14-21-day run-in phase of Ipat then surgical tumour resection. Combination Ipat+ATZ commenced post surgery. Patients who declined surgery or who were deemed high risk for surgery proceeded directly to combination. Patients in the expansion cohort B3 commenced directly on Ipat+ATZ at the RP2D of 400mg Ipat with ATZ. Results 16 evaluable recurrent GBM pts were enrolled across two cohorts. Median age 56 yrs (25-71 yrs). Median ECOG PS 1. Median lines of prior therapy 1 (range 1-4). 10 pts had PTEN loss by IHC (H<30) and/or PTEN mutations on next generation sequencing. No DLTs, treatment-related (TR) serious adverse events (AEs), or immune-related AEs were observed. Most common TR AEs were G1 diarrhoea (44%), mucositis (17%), rash (28%). Clinical benefit rate (CR, PR and SD> 6 cycles) at clinical cutoff date (23/02/21) in patients with PTEN aberration was 30% (3/10). A 58-year-old man with PTEN loss had MRI at Cycle 5 showing worsening enhancement suggestive of disease progression. Resection of the lesion showed intense lymphocyte infiltration and pathological CR. He is currently on Cycle 22 with no evidence of disease. Two other patients with PTEN loss with radiological stable disease per RANO criteria remain well on study for >6 cycles. Conclusion Combination Ipat+ATZ appears safe and tolerable in GBM pts, with 400mg Ipatasertib OD + 1200mg ATZ Q3W declared as RP2D. Early efficacy signals were detected with PTEN loss being a promising predictive biomarker for response to combination. An expansion cohort enriched with pts with PTEN loss is ongoing.

scholarly journals A human CD137×PD-L1 bispecific antibody promotes anti-tumor immunity via context-dependent T cell costimulation and checkpoint blockade

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cecile Geuijen ◽  
Paul Tacken ◽  
Liang-Chuan Wang ◽  
Rinse Klooster ◽  
Pieter Fokko van Loo ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Checkpoint ◽  
Immune Checkpoint Inhibitor ◽  
Bispecific Antibody ◽  
Checkpoint Inhibitor ◽  
Checkpoint Inhibitors ◽  
Clinical Activity ◽  
Functional Screening ◽  
Anti Tumor Activity

AbstractImmune checkpoint inhibitors demonstrate clinical activity in many tumor types, however, only a fraction of patients benefit. Combining CD137 agonists with these inhibitors increases anti-tumor activity preclinically, but attempts to translate these observations to the clinic have been hampered by systemic toxicity. Here we describe a human CD137xPD-L1 bispecific antibody, MCLA-145, identified through functional screening of agonist- and immune checkpoint inhibitor arm combinations. MCLA-145 potently activates T cells at sub-nanomolar concentrations, even under suppressive conditions, and enhances T cell priming, differentiation and memory recall responses. In vivo, MCLA-145 anti-tumor activity is superior to immune checkpoint inhibitor comparators and linked to recruitment and intra-tumor expansion of CD8 + T cells. No graft-versus-host-disease is observed in contrast to other antibodies inhibiting the PD-1 and PD-L1 pathway. Non-human primates treated with 100 mg/kg/week of MCLA-145 show no adverse effects. The conditional activation of CD137 signaling by MCLA-145, triggered by neighboring cells expressing >5000 copies of PD-L1, may provide both safety and potency advantages.

scholarly journals Multiplex Immunohistochemical Phenotyping of T Cells in Primary Prostate Cancer

2021 ◽  
Author(s):  
Busra Ozbek ◽  
Onur Ertunc ◽  
Andrew Erikson ◽  
Igor Damasceno Vidal ◽  
Carolina Gomes Alexandre ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Checkpoint Inhibitors ◽  
T Cell Subsets ◽  
Epithelial Tumor ◽  
Stromal Compartment ◽  
Tissue Samples ◽  
Pten Loss

Most prostate cancers are 'immune cold'and poorly responsive to immune checkpoint inhibitors. However, the mechanisms responsible for the lack of a robust anti-tumor adaptive immune response in the prostate are poorly understood, which hinders the development of novel immunotherapeutic approaches. In addition, most inflammatory infiltrates in the prostate are centered around benign glands and stroma, which can confound the molecular characterization of the anti-tumor immune response. We analytically validated a chromogenic-based multiplex IHC approach and performed whole slide digital image analysis to quantify T cell subsets from the tumor microenvironment (TME) of primary prostatic adenocarcinomas. We trained a classifier to quantify the densities of eight T cell phenotypes separately in the tumor epithelial and stromal subcompartments. As an initial application, we tested the hypothesis that PTEN loss leads to an altered anti-tumor immune response by comparing matched regions of tumors within the same individual with and without PTEN loss. Our main findings in carcinomas (benign removed) include the following: i) CD4+ T cells are present at higher density than CD8+ T cells; ii) All T cell subsets are present at higher densities in the stromal compartment compared to the epithelial tumor compartment; iii) most CD4+ and CD8+ T cells are PD1+; iv) cancer foci with PTEN loss harbored increased numbers of T cells compared to regions without PTEN loss, in both stromal and epithelial compartments; v) the increases in T cells in PTEN loss regions were associated with ERG gene fusion status. This modular approach can apply to any IHC-validated antibody combination, sets the groundwork for more detailed spatial analyses, can help preserve small tissue samples, and can complement single cell and spatial genomic approaches.

scholarly journals PTEN loss correlates with T cell exclusion across human cancers

BMC Cancer ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ziying Lin ◽  
Lixia Huang ◽  
Shao Li Li ◽  
Jincui Gu ◽  
Xiaoxian Cui ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Helper Cells ◽  
Pi3k Pathway ◽  
T Helper ◽  
Immune Microenvironment ◽  
Pten Loss ◽  
Pathway Activation ◽  
Tumor Types ◽  
T Cell Exclusion

Abstract Background Recent evidences had shown that loss in phosphatase and tensin homolog deleted on chromosome 10 (PTEN) was associated with immunotherapy resistance, which may be attributed to the non-T-cell-inflamed tumor microenvironment. The impact of PTEN loss on tumor microenvironment, especially regarding T cell infiltration across tumor types is not well understood. Methods Utilizing The Cancer Genome Atlas (TCGA) and publicly available dataset of immunotherapy, we explored the correlation of PTEN expressing level or genomic loss with tumor immune microenvironment and response to immunotherapy. We further investigated the involvement of PI3K-AKT-mTOR pathway activation, which is known to be the subsequent effect of PTEN loss, in the immune microenvironment modulation. Results We reveal that PTEN mRNA expression is significantly positively correlated with CD4/CD8A gene expression and T cells infiltration especially T helpers cells, central memory T cell and effector memory T cells in multiples tumor types. Genomic loss of PTEN is associated with reduced CD8+ T cells, type 1 T helper cells, and increased type 2 T helper cells, immunosuppressed genes (e.g. VEGFA) expression. Furthermore, T cell exclusive phenotype is also observed in tumor with PI3K pathway activation or genomic gain in PIK3CA or PIK3CB. PTEN loss and PI3K pathway activation correlate with immunosuppressive microenvironment, especially in terms of T cell exclusion. PTEN loss predict poor therapeutic response and worse survival outcome in patients receiving immunotherapy. Conclusion These data brings insight into the role of PTEN loss in T cell exclusion and immunotherapy resistance, and inspires further research on immune modulating strategy to augment immunotherapy.

scholarly journals 250 Spatial-transcriptomic analysis of tumor-immune microenvironment in AML patients receiving pembrolizumab and decitabine

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A270-A270
Author(s):  
Chen Zhao ◽  
Abigail Wong-Rolle ◽  
Prajan Divakar ◽  
Katherine Calvo ◽  
Christopher Hourigan
Keyword(s):  
T Cells ◽  
T Cell ◽  
Checkpoint Inhibitors ◽  
Treatment Strategies ◽  
Transcriptomic Analysis ◽  
Inadequate Response ◽  
Immune Microenvironment ◽  
Clinical Center ◽  
Tumor Immune Microenvironment ◽  
Refractory Acute Myeloid Leukemia

BackgroundRelapsed or refractory Acute Myeloid Leukemia (R-AML) is a deadly disease with an inadequate response rate to current treatments. Recent advances in immunotherapy shed light on R-AML, and several clinical trials have shown promising potential for combining immune checkpoint inhibitors (ICIs) with hypomethylating agents. A deeper understanding of the tumor-immune microenvironment in R-AML during combination ICI treatment is urgently needed for developing better therapeutics and stratifying treatment strategies.MethodsTo dissect the tumor-immune interactions in the bone marrow microenvironment, we employed nanoString GeoMx Digital Spatial Profiler (DSP) and performed a spatial-transcriptomic analysis of patients with R-AML who received pembrolizumab and decitabine. We compared the transcriptomic profiles and TCR clonalities of tumor-interacting T cells, bystander T cells, and other cells at baseline, post-pembrolizumab treatment, and post-decitabine, which enable us to identify R-AML’s suppressive immune microenvironment and immune cells’ responses to ICI and hypomethylating agent.ResultsWe obtained the spatial-transcriptomic profiles of T cells, stromal cells, and leukemia cells in patients with R-AML at different treatment points. Our TCR-specific probes were able to track T cell clonal changes during treatments.ConclusionsR-AML harbored a complex tumor immune microenvironment and diverse T cell clonality.AcknowledgementsThis research was supported in part by the Intramural Research Program of the NCI (the Center for Cancer Research), NHLBI, and NIH Clinical Center.Ethics ApprovalThis study is approved by NHLBI IRB.

scholarly journals Strategies to Improve the Antitumor Effect of γδ T Cell Immunotherapy for Clinical Application

2021 ◽  
Vol 22 (16) ◽  
pp. 8910
Author(s):  
Masatsugu Miyashita ◽  
Teruki Shimizu ◽  
Eishi Ashihara ◽  
Osamu Ukimura
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Checkpoint ◽  
Checkpoint Inhibitors ◽  
Γδ T Cells ◽  
Target Cells ◽  
Γδ T Cell ◽  
Antitumor Effects ◽  
Cell Immunotherapy ◽  
T Cell Immunotherapy

Human γδ T cells show potent cytotoxicity against various types of cancer cells in a major histocompatibility complex unrestricted manner. Phosphoantigens and nitrogen-containing bisphosphonates (N-bis) stimulate γδ T cells via interaction between the γδ T cell receptor (TCR) and butyrophilin subfamily 3 member A1 (BTN3A1) expressed on target cells. γδ T cell immunotherapy is classified as either in vivo or ex vivo according to the method of activation. Immunotherapy with activated γδ T cells is well tolerated; however, the clinical benefits are unsatisfactory. Therefore, the antitumor effects need to be increased. Administration of γδ T cells into local cavities might improve antitumor effects by increasing the effector-to-target cell ratio. Some anticancer and molecularly targeted agents increase the cytotoxicity of γδ T cells via mechanisms involving natural killer group 2 member D (NKG2D)-mediated recognition of target cells. Both the tumor microenvironment and cancer stem cells exert immunosuppressive effects via mechanisms that include inhibitory immune checkpoint molecules. Therefore, co-immunotherapy with γδ T cells plus immune checkpoint inhibitors is a strategy that may improve cytotoxicity. The use of a bispecific antibody and chimeric antigen receptor might be effective to overcome current therapeutic limitations. Such strategies should be tested in a clinical research setting.

scholarly journals Evaluation of Various Strategies to Generate NPM1mut-Specific T Cell Clones

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5718-5718 ◽  
Author(s):  
Elke Ruecker-Braun ◽  
Falk Heidenreich ◽  
Cornelia S Link ◽  
Maria Schmiedgen ◽  
Rebekka Wehner ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Checkpoint Inhibitors ◽  
Single Cells ◽  
Molecular Genetic ◽  
Specific Antigen ◽  
Positive Control ◽  
Low Frequencies ◽  
T Cell Clones ◽  
Cell Clones

Abstract Mutated nucleophosmin (NPM1) was identified as a promising leukemia-specific antigen for cytotoxic T lymphocytes (CTL). NPM1 is a multifunctional nucleocytoplasmic shuttling phosphoprotein. In AML patients with normal cytogenetics NPM1 mutations are the most frequent molecular genetic abnormalities, accounting for up to 60% of the patients. The peptide (AIQDLCLAV) derived from the mutated NPM1 (NPM1mut) has been described to elicit a CTL response restricted to HLA-A*02:01. We observed that NPM1mut multimer+ T cells were very rare in peripheral blood. The limitation of the multimer technology is the absence of a positive control; nevertheless it is an attractive tool to generate antigen positive T cell clones. The goal was to compare strategies for the generation of NPM1mut multimer+ T cell clones systematically. For this purpose we analyzed blood samples from two patients with AML after transplantation and six different healthy donors. We explored different strategies to isolate HLA-A*02:01 restricted NPM1mut multimer+ T single cells. The first strategy was to isolate multimer+ T cells directly from the blood without any supplements by single cell sorting. The second strategy was to sort multimer+ T cells which were previously CD8+ enriched supplementing the media either with or without IL-21. Published by Yongqing et al.IL-21 enhances the generation of human antigen-specific CD8+ T cells. A further strategy was to previously enrich CD14+ cells for the generation of autologous monocyte-derived dendritic cells (MoDCs). The co-cultivation of MoDCs loaded with the NPM1mut peptide and CD8+ cells were performed either with or without IL-21, as well. We expanded the last strategy by a second round of NPM1mut-specific stimulation. So far it was not possible to generate NPM1mut-specific T cell clones based on the advanced strategies and consistently there is no data published on NPM1mut multimer+ T cell clones. This fact raises the question why NPM1mut specific clones display such low frequencies. We want to point out that although we varied the strategies and we used eight different donors the isolation of NPM1mut-specific T cells restricted to HLA-A*02:01 apparently is challenging. Greater efforts, e.g. a larger number of donors or the use of immunological checkpoint inhibitors during cell culture are needed. Disclosures Thiede: AgenDix: Employment, Other: Ownership. Schetelig:Sanofi: Honoraria.

scholarly journals Early Investigations and Recent Advances in Intraperitoneal Immunotherapy for Peritoneal Metastasis

Vaccines ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 54 ◽  
Author(s):  
Anusha Thadi ◽  
Marian Khalili ◽  
William Morano ◽  
Scott Richard ◽  
Steven Katz ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Peritoneal Metastasis ◽  
Checkpoint Inhibitors ◽  
Folate Receptor ◽  
Malignant Ascites ◽  
T Cell Response ◽  
Adoptive Cell Transfer ◽  
Car T Cells ◽  
Car T

Peritoneal metastasis (PM) is an advanced stage malignancy largely refractory to modern therapy. Intraperitoneal (IP) immunotherapy offers a novel approach for the control of regional disease of the peritoneal cavity by breaking immune tolerance. These strategies include heightening T-cell response and vaccine induction of anti-cancer memory against tumor-associated antigens. Early investigations with chimeric antigen receptor T cells (CAR-T cells), vaccine-based therapies, dendritic cells (DCs) in combination with pro-inflammatory cytokines and natural killer cells (NKs), adoptive cell transfer, and immune checkpoint inhibitors represent significant advances in the treatment of PM. IP delivery of CAR-T cells has shown demonstrable suppression of tumors expressing carcinoembryonic antigen. This response was enhanced when IP injected CAR-T cells were combined with anti-PD-L1 or anti-Gr1. Similarly, CAR-T cells against folate receptor α expressing tumors improved T-cell tumor localization and survival when combined with CD137 co-stimulatory signaling. Moreover, IP immunotherapy with catumaxomab, a trifunctional antibody approved in Europe, targets epithelial cell adhesion molecule (EpCAM) and has shown considerable promise with control of malignant ascites. Herein, we discuss immunologic approaches under investigation for treatment of PM.

Modeling and simulation of the “IL-36 cytokine” and CAR-T cells interplay in cancer onset

2021 ◽  
Author(s):  
Khaled A. Al-Utaibi ◽  
Alessandro Nutini ◽  
Ayesha Sohail ◽  
Robia Arif ◽  
Sümeyye Tunc ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Adoptive Immunotherapy ◽  
Checkpoint Inhibitors ◽  
Antitumor Action ◽  
Adoptive Therapy ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Background: CAR-T cells are chimeric antigen receptor (CAR)-T cells; they are target-specific engineered cells on tumor cells and produce T cell-mediated antitumor responses. CAR-T cell therapy is the “first-line” therapy in immunotherapy for the treatment of highly clonal neoplasms such as lymphoma and leukemia. This adoptive therapy is currently being studied and tested even in the case of solid tumors such as osteosarcoma since, precisely for this type of tumor, the use of immune checkpoint inhibitors remained disappointing. Although CAR-T is a promising therapeutic technique, there are therapeutic limits linked to the persistence of these cells and to the tumor’s immune escape. CAR-T cell engineering techniques are allowed to express interleukin IL-36, and seem to be much more efficient in antitumoral action. IL-36 is involved in the long-term antitumor action, allowing CAR-T cells to be more efficient in their antitumor action due to a “cross-talk” action between the “IL-36/dendritic cells” axis and the adaptive immunity. Methods: This analysis makes the model useful for evaluating cell dynamics in the case of tumor relapses or specific understanding of the action of CAR-T cells in certain types of tumor. The model proposed here seeks to quantify the action and interaction between the three fundamental elements of this antitumor activity induced by this type of adoptive immunotherapy: IL-36, “armored” CAR-T cells (i.e., engineered to produce IL-36) and the tumor cell population, focusing exclusively on the action of this interleukin and on the antitumor consequences of the so modified CAR-T cells. Mathematical model was developed and numerical simulations were carried out during this research. The development of the model with stability analysis by conditions of Routh–Hurwitz shows how IL-36 makes CAR-T cells more efficient and persistent over time and more effective in the antitumoral treatment, making therapy more effective against the “solid tumor”. Findings: Primary malignant bone tumors are quite rare (about 3% of all tumors) and the vast majority consist of osteosarcomas and Ewing’s sarcoma and, approximately, the 20% of patients undergo metastasis situations that is the most likely cause of death. Interpretation: In bone tumor like osteosarcoma, there is a variation of the cellular mechanical characteristics that can influence the efficacy of chemotherapy and increase the metastatic capacity; an approach related to adoptive immunotherapy with CAR-T cells may be a possible solution because this type of therapy is not influenced by the biomechanics of cancer cells which show peculiar characteristics.

EP.WE.805From bench to bedside; A rationale for Immunotherapy in the adjuvant setting for Oesophageal cancer

2021 ◽  
Vol 108 (Supplement_7) ◽  
Author(s):  
Noel Donlon ◽  
Maria Davern ◽  
Andrew Sheppard ◽  
John Reynolds ◽  
Joanne Lysaght
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Immune Checkpoint ◽  
Cell Activation ◽  
Single Agent ◽  
T Cell Subsets ◽  
Effector Memory ◽  
Post Surgery ◽  
Post Operative Period

Abstract Background Immunotherapy is being intensively investigated for its utilisation in the curative setting as a single agent and in the multimodal setting, however, the most appropriate time to incorporate ICIs remains unknown. Our study profiles systemic anti-tumour immunity perioperatively to provide a rationale for adjuvant immunotherapy. Methods Systemic immunity was immunophenotyped pre and post-oesophagectomy on days 0, 1, 3, 7 and week 6 by flow cytometry (n = 14). The frequency of circulating lymphocytes, T cells, cytotoxic and helper T lymphocytes was profiled longitudinally including the proportion of T cell subsets in circulation. This study also profiled immune checkpoint expression on circulating T cells including: PD-1, CTLA-4, TIGIT, TIM-3, LAG-3, PD-L1 and PD-L2. Markers of immunogenicity (calreticulin, HMGB1 and MIC-A/B) were also assessed. Results The frequency of circulating CD27 + T cells increases sequentially in the immediate post-operative period peaking on day 7 in OAC patients. (p < 0.01) There is a sequential decrease in the percentage of effector memory and central memory T cells in circulation and an increase in the percentage of naïve T cells in peripheral circulation of OAC patients in the immediate post-operative period. The expression of CTLA-4 on the surface of circulating CD4 + T cells decreases 6 weeks post-operatively in OAC patients. Conclusions We observed increased T cell activation and immune checkpoints immediately post-surgery with returns to baseline by week 6. These results suggest that immune checkpoint inhibitors such as anti-PD-1 may be beneficial immediately post-surgery to maintain T cell activation and prevent exhaustion of this increased population of activated T cells observed immediately post-surgery.

Differentiated activity profile for the PD-1 inhibitor balstilimab.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. 5529-5529
Author(s):  
Cailin Joyce ◽  
Dhan Chand ◽  
Benjamin Duckless ◽  
Manuel Hidalgo ◽  
Joseph Elan Grossman ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
T Cells ◽  
T Cell ◽  
Cancer Cells ◽  
Culture System ◽  
Checkpoint Inhibitors ◽  
Objective Response ◽  
Activity Profile ◽  
Double Positive ◽  
Programmed Death

5529 Background: The development and clinical application of immune checkpoint inhibitors has transformed the therapeutic landscape for cancer treatment in recent years. Balstilimab (AGEN2034) is a fully human, monoclonal IgG4 antibody that binds with high affinity to programmed death 1 (PD-1), thus preventing the interaction between this receptor and its ligands programmed death ligand 1 and 2 (PD-L1, PD-L2). Emerging evidence suggests that balstilimab exhibits a differentiated activity profile compared to currently approved anti-PD-1 agents, including pembrolizumab and nivolumab. Methods: Balstilimab as monotherapy was evaluated in a large phase 2 study in patients (pts) with recurrent/metastatic cervical cancer who had relapsed after a platinum-based treatment regimen for advanced disease. Pts were dosed at 3 mg/kg once every 2 weeks for up to 24 months and antitumor activity was assessed using RECIST v1.1. The tumor cell killing activity of balstilimab was evaluated preclinically in a human co-culture system of (1) primary T cells engineered to recognize NY-ESO-1 and (2) NY-ESO-1+ cancer cell lines, including PD-L1 and/or PD-L2-deficient engineered lines. The co-culture system was maintained for ̃ two weeks to drive partial T cell exhaustion; a state where cytotoxicity is compromised but recoverable with PD-1 blockade. Cytotoxicity of these partially exhausted T cells was quantified against PD-L1/L2 double positive, single positive, or double negative cancer cells in the presence or absence of PD-(L)1 antibodies. Results: In the second-line treatment setting for pts with advanced cervical cancer, balstilimab showed a numerically higher objective response rate (ORR) in subjects with PD-L1+, squamous cell carcinoma (SCC) tumors (21%, 95% CI, 12.7-32.6%) than those reported for pembrolizumab. Unlike pembrolizumab, balstilimab showed activity in PD-L1(-) pts, and irrespective of tumor histology (ORR 7.9%, 95% CI, 2.7-20.8%). Despite lower overall PD-L1 positivity compared to SCC (41.7 v 72.9%), an ORR of 12.5% (95% CI, 5.9-24.7%) was observed in the subset of pts with a poorer prognosis, those with cervical adenocarcinoma. Concordant with clinical observations, balstilimab demonstrated superior rescue of antigen-specific T cell cytotoxicity in vitro relative to pembrolizumab, nivolumab, or atezolizumab. Balstilimab also induced cytotoxicity against PD-L1 and/or PD-L2 deficient target cancer cells. Conclusions: Taken together, these data suggest functional differentiation of balstilimab from other PD-1 inhibitors with potentially important implications for extending the therapeutic reach of anti-PD-1 therapy. Investigation of the underlying mechanistic basis for these findings is ongoing. Clinical trial information: NCT03104699.

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