PD-1 Monoclonal Antibody Research Articles

Combination of PD-1 Monoclonal Antibody and HPV Vaccine in Patients With Cervical Cancer

Combination of PD-1 Monoclonal Antibody and HPV Vaccine in Patients With Cervical Cancer

Treatment of Non-small Cell Lung Cancer With PD-1 Monoclonal Antibody Combined With Donafenib Toluene Sulfonate

Treatment of Non-small Cell Lung Cancer With PD-1 Monoclonal Antibody Combined With Donafenib Toluene Sulfonate

Abstract 3264: A novel TLR8 agonist induces immune responses and tumor regression

Abstract Toll like receptors (TLRs) have been a recent focus of drug discovery for cancer immunotherapy. TLRs play a crucial role in bridging innate and adaptive immunity. TLR8 is distinguished from other TLRs by its functions in reversing regulatory T (Treg) cell and myeloid derived suppressor cell (MDSC)’s immune suppression effects. Treg and MDSCs induce an immunosuppressive microenvironment that is a major cause of failed tumor immunotherapy. Therefore, activation of TLR8 can exert potent immune-mediated anticancer activity. We discovered a novel TLR8 selective agonist DN052 and demonstrated that DN052 clearly differentiated from motolimod, the only TLR8 agonist drug candidate in clinical development. DN052 was more potent than motolimod and exhibited better PK profiles and more strongly induced immune responses in the in vivo monkey and ex vivo human PBMC studies. However, it has been challenging to characterize TLR8 agonists in vivo partially due to the phylogenetic specificity of TLR8 and its diminished activity in rodents. We developed two new in vivo approaches using mouse syngeneic and mouse xenograft tumor models. Our in vivo studies showed that DN052 strongly suppressed tumor growth in a dose-dependent manner as a single agent and combination with the chemotherapeutic agent or PD-1 monoclonal antibody further enhanced the efficacy of the single agents in several tumor models. Remarkably, DN052 caused complete tumor regression as a single agent or in combination in some of the immune-competent tumor-bearing mice. GLP toxicity studies in rats and monkeys showed that DN052 had favorable safety profiles. Taken together, DN052 is a novel Best-in-Class TLR8 selective agonist for immunotherapy as a single agent or in combination with other immuno-oncology agents or chemotherapeutics for broad cancer indications. DN052 warrants further clinical development. Citation Format: Yuxun Wang, Heping Yang, Huanping Li, Shuda Zhao, Yin Zhang, Renjie Huang, Jinmiao Wu, Yikun Zeng, Panpan Zhang, Xingzhong Zhang, Longsheng Wang, Guangliang Fu, Zhiheng Wu, Panhu Zhu, Hui Xu, Yaqiao Gao, Pei Wang, Daxin Gao. A novel TLR8 agonist induces immune responses and tumor regression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3264.

Abstract 4121: Preclinical characterization of CS1003, a novel clinical-stage PD-1 monoclonal antibody

Abstract Background: The programmed cell death protein 1 receptor (PD-1) is an immune-checkpoint protein that negatively regulates the immune system to avoid collateral damage to self-tissues. Tumors hijack this mechanism as a way to avoid immune detection and destruction. Presently, the FDA has approved three anti-PD-1 antibodies for the treatment in more than ten cancer types. CS1003 is a novel anti-PD-1 mAb recognizing a unique epitope developed to disrupt the PD-1 interaction with PD-L1/PD-L2 to restore or improve T-cell function as stand-alone therapy or in combination with other approaches. Methods: A panel of rat PD-1 mAbs were generated through conventional hybridoma technology. Several mAbs with favorable characteristics were further humanized. CS1003, a humanized, hinge-stabilized IgG4 mAb, was selected as our lead candidate for further characterization including antigen binding, biophysical properties as well as functional characterization. Results: CS1003 binds mouse, cynomolgus monkey and human PD-1 with similar affinity. CS1003 bound PD-1-expressing cell lines and chronically-activated T cells, blocked PD-1 interactions with PD-L1/PD-L2, resulting in inhibition of PD-1 signaling, and enhanced T cell cytokine secretion and proliferation to levels comparable to those observed with nivolumab or pembrolizumab reference molecules. CS1003 showed significantly anti-tumor activity in conventional MC38 as well as in hPD-1 knock-in mice. CS1003 showed no unexpected cross-reactivity in human tissues, with specific staining observed primarily in lymphocytes of lymphoid organs. In a pharmacokinetic (PK) study in cynomolgus monkeys following single intravenous administration at multiple dose levels, PK properties were linear with the proportionally increasing exposures from 2-18 mg/kg. In a repeated-dose toxicity study, CS1003 was well tolerated in cynomolgus monkeys and the major finding was mononuclear infiltration in multiple organs, which was consistent with its pharmacologic activity. CS1003 demonstrated a favorable safety profile with the highest non-severely toxic dose (HNSTD) of 100 mg/kg. Conclusion: CS1003 is a novel anti-PD-1 mAb with favorable preclinical characteristics and safety profile in cynomolgus monkeys. The unique feature of CS1003 is its cross-reactivity with both human and murine PD-1. This should greatly facilitate further evaluation its potential for combination therapy in various syngeneic mouse tumor models. A phase I study for CS1003 is being conducted to evaluate the safety, tolerability, PK and anti-tumor activity in patients with advanced tumors [NCT03475251]. Citation Format: Fu Li, Jingrong Li, Ke Yin, Juan Zhang, Zhenhu Li, Liang Lu, Yuanwu Bao, Dan Pu, Zhen Qin, Yong Zheng, Baotian Yang, Jing Li, Xinzhong Jon Wang. Preclinical characterization of CS1003, a novel clinical-stage PD-1 monoclonal antibody [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4121.

Abstract CT046: Predictive biomarkers and pharmacodynamic changes in tumor RNA expression in a phase I study of anti PD-1 monoclonal antibody PF-06801591

Abstract Introduction: PF-06801591 is a humanized IgG4 monoclonal antibody that binds to programmed cell death (PD-1) receptor, blocking its interaction with PD-1 ligands. In a phase I study (NCT02573259; dose-escalation) of 40 patients (pts) with multiple solid tumor types treated with PF-06891591 intravenously (IV) or subcutaneously (SC), 7 pts showed partial response. PF-06801591 was well tolerated at all doses. Biopsy samples were evaluated for predictive biomarkers and pharmacodynamic effects. Methods: Biopsy samples at baseline and on-treatment (IV:day 29; SC:day 36) were collected from 4 dose cohorts (IV:1, 3 and 10 mg/kg; SC:300 mg). Whole-exome sequencing (WES) and RNA-seq of biopsy tissue were used to estimate tumor mutation burden (TMB) and gene expression. Regression analysis was used to identify TMB/genes/pathways potentially associated with response in baseline tissue. Differential analysis of baseline and on-treatment biopsies identified genes/pathways potentially upregulated by PF-06801591. PD-L1 (clone SP-263; Ventana) expression was evaluated in tumor biopsies by immunohistochemistry (IHC) and pathologist scoring. Results: In a combined WES analysis of samples from baseline biopsies (all doses, n=24 pts), higher TMB was significantly associated with improved objective response (R^2=0.215, P=0.013). From RNA-seq analysis, genes positively associated with response were involved in interferon-gamma (IFNG) and PD-1 signaling, and cell cycle; CTLA4 was among the genes most significantly associated with response (P<0.001). Response was better correlated with levels of PD-L1 RNA (P=0.028) than PD-L1 protein (IHC; P=0.39 to 0.84). RNA-seq analysis of paired baseline and on-treatment biopsies (all doses) showed increased expression of genes involved in adaptive immune response pathways, including chemokines and chemokine receptors such as CXCL9. Decreased expression of cell cycle genes such as CDKN1B was observed in on-treatment biopsies. Conclusion: Based on a mixed set of tumor types with possible sensitivity to anti-PD-1, high TMB, IFNG signaling, and PD-L1 were associated with response to PF-06801591, as reported for other anti-PD-1 antibodies. Albeit based on a small sample size and diverse indication profile, baseline expression of CTLA4 appears to be highly associated with response and PD-L1 RNA levels may be better associated with response than protein expression by IHC. Increased expression of genes/pathways associated with adaptive immune activation in on-treatment biopsies indicates an active, immunomodulatory mechanism with anti-PD-1 therapy. This ongoing study will evaluate predictive biomarkers in dose-expansion cohorts of PF-06801591 in non-small cell lung cancer and urothelial cancer. Acknowledgments Study sponsor: Pfizer. Medical writing support: Chu Kong Liew (Engage Scientific Solutions), funded by Pfizer. Citation Format: Siwen Hu-Lieskovan, Fadi Braiteh, Juneko E. Grilley-Olson, Shobha Potluri, Xiao Wang, Alison Forgie, Vinicius Bonato, Jeffrey Chou, Melissa L. Johnson. Predictive biomarkers and pharmacodynamic changes in tumor RNA expression in a phase I study of anti PD-1 monoclonal antibody PF-06801591 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT046.

Abstract 1453: Development of a novel PD-1 vaccine and in combination with two Chimeric HER-2 peptide vaccine provides synergistic inhibition of tumor growth in a syngeneic Balb/c model challenged with CT26/HER-2 carcinoma cell line

Abstract Background: Therapeutic blockade of the signaling axis between PD-1 and its ligand programmed cell death ligand-1 (PD-L1) with monoclonal antibodies has shown remarkable clinical success in the treatment of cancer and demonstrated impressive activity across a broad set of cancer subtypes, even at advanced and metastatic stages of disease. Contrary to treatment with monoclonal antibodies, chimeric B-cell cancer vaccines have the advantage of producing a specific immune response that can potentially induce memory B & T cell responses, while reducing immune evasion and suppression. Methods: We have translated two HER-2 combination peptide vaccines (B-Vaxx) to the clinic in a Phase 1/2b trial to safely deliver curative and transformative cancer immunotherapies to advanced cancer patients. We have created and established the development of a novel B-cell peptide vaccine (Key-Vaxx) with high immunogenicity that binds to human PD-1 and produces tumor inhibition in vivo in an animal model of colon cancer. Here, we describe the transferable CT-26-HER2 neu tumor model in Balb/c was used to test for synergistic effects of anti-PD1 immunization therapy in combination with anti-HER2 immunization therapy to determine whether this combination could increase immunogenicity, enhance anti-tumor responses and provide synergistic benefit in inhibiting tumor growth. Results: We show robust HER-2 and PD-1 antibody responses in all vaccinated mice indicating that the combined vaccination is effective in reducing tumor growth in a Balb/c syngeneic model of colon carcinoma versus either the PD-1 vaccine or more importantly the positive control gold standard that is anti-mouse PD-1 monoclonal antibody. The vaccine combination was found to be safe and did not appear to exhibit toxicity or autoimmunity. Conclusion: Development of a novel PD-1 vaccine in combination with two Chimeric HER-2 peptide vaccine provides synergistic inhibition of tumor growth with no evidence of toxicity or autoimmunity. A clinical trial with the combination is under planning. Citation Format: Tanios Bekaii-Saab, Jay Overholser, Yuhong Yang, Manuel Penichet, Pravin Kaumaya. Development of a novel PD-1 vaccine and in combination with two Chimeric HER-2 peptide vaccine provides synergistic inhibition of tumor growth in a syngeneic Balb/c model challenged with CT26/HER-2 carcinoma cell line [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1453.

Preliminary safety, efficacy, and pharmacokinetic/pharmacodynamic characterization from GARNET, a phase I/II clinical trial of the anti–PD-1 monoclonal antibody, TSR-042, in patients with recurrent or advanced MSI-h and MSS endometrial cancer

Preliminary safety, efficacy, and pharmacokinetic/pharmacodynamic characterization from GARNET, a phase I/II clinical trial of the anti–PD-1 monoclonal antibody, TSR-042, in patients with recurrent or advanced MSI-h and MSS endometrial cancer

HK3 Is Correlated with Immune Infiltrates and Predicts Response to Immunotherapy in NSCLC

Along with increasing understanding of tumor immune biology, recent breakthroughs in cancer immunotherapies have shed a new light on cancer therapy. However, only about 20% of treated patients have durable responses, while all are at risk for side effects.It is crucial to figure out the underly regulation mechanism of the immune microenvironment of NSCLC to improve the benefit of immuotherapy. Hexokinases-3(HK3) phosphorylate glucose to produce glucose-6-phosphate, the first step in most glucose metabolism pathways. Recent study reported functional role of HK3 in acute promyelocytic leukemia and colorectal cancer. In this present study, we studied the co-expression relationship between the glycolytic pathway gene and the immune checkpoint gene, and found that the expression of HK3 in tumor tissue may be related to immune status. By analyzing the TCGA data we found that HK3 expression was highly correlated with major clinical and molecular characteristics. Cases with low HK3 expression were more likely to be predicted as malignant entities and frequent with genomic aberrations of driver oncogenes. Moreover, gene ontology analysis based on significantly correlated genes of HK3 expression exhibited that HK3 was associated with immune responses and inflammatory activities. In addition, HK3 shows a significant trend in predicting the efficacy of immunotherapy for patients accept Keytruda (PD-1 monoclonal antibody) treatment. This study is the first integrative study characterizing HK3 expression of NSCLC both in molecular and clinic. Funding Statement: This work was supported by the grants from the National Natural Science Foundation of China (NO. 81472708). Declaration of Interests: The authors declare no potential conflicts of interest. Ethics Approval Statement: All protocols using human samples were reviewed and approved by the Ethical Committee of Huazhong University of Science and Technology. Written informed consent was obtained from all patients.

The Role of Membrane Bound Complement Regulatory Proteins in Tumor Development and Cancer Immunotherapy.

It has long been understood that the control and surveillance of tumors within the body involves an intricate dance between the adaptive and innate immune systems. At the center of the interplay between the adaptive and innate immune response sits the complement system—an evolutionarily ancient response that aids in the destruction of microorganisms and damaged cells, including cancer cells. Membrane-bound complement regulatory proteins (mCRPs), such as CD46, CD55, and CD59, are expressed throughout the body in order to prevent over-activation of the complement system. These mCRPs act as a double-edged sword however, as they can also over-regulate the complement system to the extent that it is no longer effective at eliminating cancerous cells. Recent studies are now indicating that mCRPs may function as a biomarker of a malignant transformation in numerous cancer types, and further, are being shown to interfere with anti-tumor treatments. This highlights the critical roles that therapeutic blockade of mCRPs can play in cancer treatment. Furthermore, with the complement system having the ability to both directly and indirectly control adaptive T-cell responses, the use of a combinatorial approach of complement-related therapy along with other T-cell activating therapies becomes a logical approach to treatment. This review will highlight the biomarker-related role that mCRP expression may have in the classification of tumor phenotype and predicted response to different anti-cancer treatments in the context of an emerging understanding that complement activation within the Tumor Microenvironment (TME) is actually harmful for tumor control. We will discuss what is known about complement activation and mCRPs relating to cancer and immunotherapy, and will examine the potential for combinatorial approaches of anti-mCRP therapy with other anti-tumor therapies, especially checkpoint inhibitors such as anti PD-1 and PD-L1 monoclonal antibodies (mAbs). Overall, mCRPs play an essential role in the immune response to tumors, and understanding their role in the immune response, particularly in modulating currently used cancer therapeutics may lead to better clinical outcomes in patients with diverse cancer types.

Gene mutations of SWI/SNF complex and molecular profile in colorectal cancer.

3600 Background: The SWI/SNF complex includes proteins produced by 29 genes that regulate chromatin structure remodeling through effects upon transcription, replication, and repair. Understanding how SWI/SNF gene mutations interact to affect cancer progression could lead to new treatment strategies. Methods: We analyzed 7,370 colorectal cancer (CRC) samples with immunohistochemical stains (IHC) and Next-Generation Sequencing (NGS) using a 592-gene panel to examine the association between gene mutations of the SWI/SNF complex ( ARID1A, ARID2, PBRM1, SMARCA4, SMARCB1, SMARCE1, BCL11A, BCL11B, BCL7A, SS18, and SS18L1) and molecular features. Results: The overall mutation rate of the SWI/SNF complex genes was 11.3% ( ARID1A: 7.7% , ARID2: 1.7% , SMARCA4: 1.3% , PBRM1: 1.2% , BCL11A: 1.0% , SMARCB1: 0.5% , BCL11B: 0.5% , SMARCE1: 0.3% , SS18: 0.3% , BCL7A: 0.1% , SS18L1: 0.1%). When compared to tumors with SWI/SNF wild-type genes, those tumors with SWI/SNF gene mutations showed significantly higher rates of microsatellite instability (MSI)-high (40.9% vs 2.4%, P < 0.001), tumor mutational burden (TMB)-high (>= 10mut/MB) (56.8% vs 21.6%, P < 0.001) and PD-L1 positivity (17.9% vs 5.5%, P < 0.001). Tumors with each gene mutant also had strong association with the immune profile (MSI-high, TMB-high, and PD-L1 positivity) (Table). Furthermore, even SWI/SNF gene mutant samples with microsatellite stable status were significantly associated with TMB-high (28.2%, P < 0.001) and PD-L1 positivity (10.0%, P < 0.001). Conclusions: Gene mutations of the SWI/SNF complex exhibit findings that suggest that this subgroup of CRCs may have a higher likelihood of response to PD-1 and PD-L1 targeting monoclonal antibodies. If validated in other data sets, these findings can be used to justify clinical trials with eligibility based upon the presence of mutations within the SWI/SNF complex. [Table: see text]

Efficacy of PD-1 monoclonal antibody SHR-1210 plus apatinib in patients with advanced nonsquamous NSCLC with wild‐type EGFR and ALK.

9112 Background: Our preclinical study suggested combination of PD-1 monoclonal antibody SHR-1210 and VEGFR 2 inhibitor apatinib significantly improved antitumor effects. This was an open-label, multi-center, phase 1/2 study of intravenous SHR-1210 plus oral apatinib in patients with advanced NSCLC. Here, we reported preliminary efficacy and safety outcomes of SHR-1210 plus apatinib in patients with wild‐type EGFR and ALK. Methods: In dose-escalation phase, advanced non-squamous NSCLC patients (pts) previously treated with at least 2nd line chemotherapy were enrolled to explore 2 dose levels of apatinib (250, 375mg/d) + SHR-1210 (200mg, q2w). 250mg/d of apatinib was selected to be combined with SHR-1210 in phase II trial. Pts previously treated with 1st line platinum-based chemotherapy were enrolled. Primary endpoint was ORR per RECIST 1.1. Archived or fresh tumor tissues and blood samples were taken before the treatment, PD-L1 expression and tumor mutation burden (TMB) were tested and correlated with efficacy. TMB was detected by Oseq-pan cancer panel (including 636 genes and 1.95Mb), and then calculated by in-house algorithm developed by BGI Genomics Co., Ltd. Results: 96 pts with advanced non-squamous NSCLC harboring wild‐type EGFR and ALK were recruited . 23 had ≥2 prior lines of systemic treatment, and 73 had 1 prior line of treatment. Median age was 57, male 79.8%, adenocarcinoma 93.9%, ex-smokers 56.7%. ORR and DCR in 91evaluable pts were 29.7% and 81.3%, respectively. Blood TMB (bTMB) test was available in 80/91 evaluable patients and the cut-point was 1.54 muts/Mb as determined by receiver operating characteristic curve. ORR in pts with high bTMB was 50% (19/38). At data cutoff of 20 Jan 2019, 20/27 responders were still on treatment (table). Across all 96pts, 54(56.2%) grade ≥3 TRAEs. AEs of grade ≥3 occurring in 2 or more pts included hypertension, hand-foot syndrome, gamma-glutamyl transferase increase, proteinuria, abnormal hepatic function and alkaline phosphatase increase. Conclusions: SHR-1210 plus apatinib demonstrated promising anti-tumor activity with acceptable safety in patients with non-squamous NSCLC, especially in those with high bTMB. Prospective study is needed to validate the clinical outcome and bTMB as a predictor of efficacy. Clinical trial information: NCT03083041. [Table: see text]

Incidence of thyroid dysfunctions during treatment with nivolumab for non-small cell lung cancer: Retrospective study of 105 patients

Immunotherapy is a standard not only in second line but also in first line treatment in patients with non-small cell lung cancer (NSCLC) and other tumors. Thyroid dysfunctions are the most common endocrine toxicities. To determine the incidence of thyroid dysfunctions during treatment with a PD-1 monoclonal antibody (nivolumab) in patients with NSCLC. Retrospective study of patients treated with nivolumab for NSCLC between May 2015 and December 2016; euthyroidism within the 3 months preceding immunotherapy; monitoring of thyroid function tests until stopping nivolumab, death or February 2017. Patients treated with levothyroxine, amiodarone or another immunotherapy were excluded. Among 183 patients treated, 105 fullfilled the inclusion criteria (72 males, median age: 61 years [range: 41-80]). Fifteen patients (14.3%) experienced a thyroid dysfunction; among them, compared to the "control" group (n=90), we found more females (53.3% vs. 27.8%; P=0.07), and younger patients (median age: 56 years vs. 62 years; P=0.02). Thirteen patients had thyrotoxicosis (median onset: 8 weeks), and then hypothyroidism was observed in 5 patients. Isolated hypothyroidism was rare (n=2) and late (median: 30 weeks). Three patients had anti-TPO antibodies. Three patients discontinued immunotherapy transiently due to thyroid dysfunctions. After a median follow-up of 9 months [95% CI, 7.5-10.3], one patient (6.7%) in the "thyroid dysfunctions" group and 30 patients (33.3%) in the "control" group died, with a trend toward a higher overall survival in the "thyroid dysfunctions" group (HR: 0.16 [95% CI, 0.02-1.15]; P=0.07). Thyroid dysfunctions (isolated thyrotoxicosis, biphasic thyroiditis and hypothyroidism) were common, and required patients with NSCLC to be screened during nivolumab therapy.

Unconventional immune-related phenomena observed using 18F-FDG PET/CT in Hodgkin lymphoma treated with anti PD-1 monoclonal antibodies.

Unconventional immune-related phenomena observed using 18F-FDG PET/CT in Hodgkin lymphoma treated with anti PD-1 monoclonal antibodies.

PD-1/PD-L1 pathway: Basic biology and role in cancer immunotherapy.

Over the course of past few years, cancer immunotherapy has been accompanied with promising results. However, preliminary investigations with respect to immunotherapy concentrated mostly on targeting the immune checkpoints, nowadays, emerge as the most efficient strategy to raise beneficial antitumor immune responses. Programmed cell death protein 1 (PD-1) plays an important role in subsiding immune responses and promoting self-tolerance through suppressing the activity of T cells and promoting differentiation of regulatory T cells. PD-1 is considered as an immune checkpoint and protects against autoimmune responses through both induction of apoptosis in antigen-specific T cells and inhibiting apoptosis in regulatory T cells. Several clinical trials exerting PD-1 monoclonal antibodies as well as other immune-checkpoint blockades have had prosperous outcomes and opened new horizons in tumor immunotherapy. Nonetheless, a bulk of patients have failed to respond to these newly emerging immune-based approach and the survival rate was not satisfying. Additional strategies, especially combination therapies, has been initiated and been further promising. Attempts to identify novel and well-suited predictive biomarkers are also sensed. In this review, the promotion of cancer immunotherapy targeting PD-1 immunoinhibitory pathway is discussed.

Combination of Baseline LDH, Performance Status and Age as Integrated Algorithm to Identify Solid Tumor Patients with Higher Probability of Response to Anti PD-1 and PD-L1 Monoclonal Antibodies.

Predictive biomarkers of response to immune-checkpoint inhibitors (ICIs) are an urgent clinical need. The aim of this study is to identify manageable parameters to use in clinical practice to select patients with higher probability of response to ICIs. Two-hundred-and-seventy-one consecutive metastatic solid tumor patients, treated from 2013 until 2017 with anti- Programmed death-ligand 1 (PD-L1)/programmed cell death protein 1 (PD-1) ICIs, were evaluated for baseline lactate dehydrogenase (LDH) serum level, performance status (PS), age, neutrophil-lymphocyte ratio, type of immunotherapy, number of metastatic sites, histology, and sex. A training and validation set were used to build and test models, respectively. The variables’ effects were assessed through odds ratio estimates (OR) and area under the receive operating characteristic curves (AUC), from univariate and multivariate logistic regression models. A final multivariate model with LDH, age and PS showed significant ORs and an AUC of 0.771. Results were statistically validated and used to devise an Excel algorithm to calculate the patient’s response probabilities. We implemented an interactive Excel algorithm based on three variables (baseline LDH serum level, age and PS) which is able to provide a higher performance in response prediction to ICIs compared with LDH alone. This tool could be used in a real-life setting to identify ICIs in responding patients.

Abstract B118: Development of a novel prostatic acid phosphatase-derived vaccine for the treatment of advanced prostate cancer

Abstract Our aim is to develop a new and more effective prostatic acid phosphatase (PAP) peptide-based vaccine for the treatment of advanced prostate cancer (PCa). We have previously shown that a 15mer PAP peptide-derived vaccine, when administered as a DNA vaccine, could induce PAP-specific T-cell responses and reduce the growth of implanted murine TRAMP C1-derived tumors in a syngeneic heterotopic murine model. We have subsequently developed an elongated (42mer) PAP-derived peptide in which Alanine at position 115 was replaced by Leucine.Herein, the capacity of the wild-type and mutated PAP-42mer vaccines to induce PAP-specific immune responses were compared in two pre-clinical murine models. The murine PAP-42mer sequence was evaluated in C57Bl/6 mice and the human PAP-42mer sequence in HHDII/DR1 transgenic mice. Following the identification of the most promising PAP-42mer sequence, the capacities of different delivery systems (CpG adjuvant, CAF09 adjuvant and ImmunoBody® DNA vaccine) to generate PAP-specific immunity were compared. For these studies, the responsiveness of splenocytes isolated from immunized mice following in vitro stimulation with MHC class I or class II wild-type vaccine-derived peptides (8/9 or 15 amino-acid long) was assessed using an IFNγ ELISpot assay and by immunophenotyping of splenic T-cells using flow cytometry. The ability of splenocytes to kill relevant targeT-cells after a short in vitro stimulation was assessed using a 51chromium release assay. B16 cells that had been knocked out for beta-2m gene and transfected to express chimeric HLA-A2 (HHDII), HLA-DR1 and human PAP implanted into HHDII/DR1 mice was used as a proof-of-concept model to assess the antitumor efficacy of the hPAP42mer mutated vaccine with CAF09 adjuvant in a prophylactic setting.The mutated murine and human PAP42mer-based vaccines induced a higher number of IFNγ-releasing splenocytes in response to in vitro stimulation with class I or class II vaccine-derived peptides and generated cells having a higher functional avidity. CAF09 and ImmunoBody® were superior to CpG in inducing PAP-specific immune responses, with CAF09 eliciting strong immune responses in both models, and ImmunoBody® eliciting potent immune responses in C57Bl/6 mice. Indeed, a higher proportion of CD8+ T-cells were able to release IFNγ and TNFα, to proliferate (Ki67 expression) and to degranulate (CD107a and Granzyme B expression) after short incubation with MHC class-I peptide. These vaccines strategies were also able to induce a higher proportion of memory CD8+ T-cells and the expression of PD-1 on CD8+ T-cells. Additionally, splenocytes from vaccinated mice were able to kill MHC class I peptide-pulsed targeT-cells (T2 and RMAS cells) and murine PCa cells expressing PAP (TRAMP-C1 cells) in vitro. The vaccine slowed the growth of human-PAP+-B16-derived tumors in HHDII/DR1 model and prolonged the survival (9 days delay for 30% of the mice). Splenic CD8+ T-cells and CD8+ tumor-infiltrating cells from vaccinated mice released IFNγ and TNFα, proliferated and degranulated in response to in vitro stimulation with MHC class I peptide. Finally, multimer-based flow cytometric analysis of peripheral blood mononuclear cells from patients with PCa following in vitro stimulation with PAP-derived peptides demonstrated the presence of PAP42mer-reactive CD8+ T-cells. Ongoing studies are assessing the effect of combining the vaccine with checkpoint inhibition (a PD-1 monoclonal antibody) in a therapeutic setting. In summary, we have developed a vaccine strategy which induces robust anti-PAP immunity and slows the growth of implanted PAP+ cancer cell-derived tumors in vivo. The presence of PAP-specific CD8+ T-cells in the periphery of patients with advanced PCa suggests that these patients will benefit from this new approach, especially when combined with checkpoint inhibition. Citation Format: Pauline Le Vu, Jayakumar Vadakekolathu, Dennis Christensen, Lindy Durrant, Graham Pockley, Stephanie E.B. McArdle. Development of a novel prostatic acid phosphatase-derived vaccine for the treatment of advanced prostate cancer [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B118.

Abstract A218: Modulating glucocorticoid receptor-mediated signaling for enhancement of cancer immunotherapy

Abstract Glucocorticoids are a class of steroid hormones essential to the modulation of a number of physiologic processes, including cellular metabolism, neural development and immune system function. Functions of glucocorticoids are mediated through the glucocorticoid receptor (GR). Synthetic glucocorticoids are front-line therapies in the clinic for leukemia and lymphoma due to their potent induction of lymphocyte death. Glucocorticoids are also prescribed as adjuvant therapies to chemotherapies to alleviate adverse effects including nausea, emesis and allergic reactions. In the current regimen of immune checkpoint blockade therapies against solid tumors, glucocorticoids are incorporated to manage symptoms related to acute immune hyperactivation. However, given that glucocorticoids preferentially cause lymphocyte death, their inclusion in immune checkpoint blockade regimens which capitalize on cytotoxic T-cell-mediated killing of tumor cells is controversial. The precise effects of systematic glucocorticoids use on tumor development, and particularly, on the tumor-immune microenvironment comprised tumor-infiltrating leukocytes (TILs) remains unknown. Conversely, methods to antagonize glucocorticoid signaling could potentially boost lymphocyte number and function and potentiate cytotoxic T-cell-mediated killing of tumor cells. Presently, the treatment of “immune cold” solid tumor types remains a challenge for immunotherapy due low level of TILs and presence of immunosuppressive cells (including regulatory T-cells and myeloid-derived suppressor cells) in the tumor microenvironment. Pharmacologic modulation of GR presents a unique opportunity to regulate immune cell homeostasis and function with the goal of promoting a favorable tumor immune microenvironment to augment the effectiveness of cancer immunotherapies in solid tumors. Our research seeks to understand the impact of glucocorticoid modulation in the context of immune checkpoint blockade therapies in preclinical models, and to provide a rationale for selective pharmacologic modulation of GR to promote a favorable tumor immune microenvironment and increased efficacy of immunotherapies in solid tumors. We investigated GR activation and inhibition on the immune tumor microenvironment in murine syngeneic melanoma (B16), breast cancer (4T1) and colorectal cancer (CT26) models. Mice bearing allograft tumors were randomized into groups receiving synthetic glucocorticoids or GR inhibitors in combination with anti-PD-1 and anti-CTLA4 therapies. Following treatment, tumors were assessed for composition of intratumoral leukocyte infiltration by flow cytometry phenotyping. In the mouse breast cancer model (4T1), we found evidence supporting substantial lymphodepletion by dexamethasone (a synthetic glucocorticoid compound). Treatment with PD-1 and CTLA-4 blocking monoclonal antibodies increased lymphocyte infiltration into the tumor. Interestingly, immune checkpoint blockade therapies significantly raised the number of more CD4+ T helper cells than CD8+ cytotoxic T-cells in the tumor. Our future plan includes investigation of the effects of GR inhibition on TILs in murine solid tumor models, and utilization of RNA-sequencing on TILs for identification of genes and molecular pathways that provide opportunities to boost TIL function within the tumor. In summary, our work can provide insight into the fundamental molecular mechanisms by which the glucocorticoid receptor modulates the tumor immune microenvironment and provide novel avenues for enhancing cancer immunotherapies in solid tumors. Citation Format: Qin Tang, Myles A. Brown. Modulating glucocorticoid receptor-mediated signaling for enhancement of cancer immunotherapy [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A218.

Design and Synthesis of A PD-1 Binding Peptide and Evaluation of Its Anti-Tumor Activity.

Immune-checkpoint blockades, suchas PD-1 monoclonal antibodies, have shown new promising avenues to treat cancers. Failure responsesof many cancer patients to these agents have led to a massive need for alternative strategies to optimize tumor immunotherapy. Currently, new therapeutic developments involve peptide blocking strategies, as they have high stability and low immunogenicity. Here, we have designed and synthesized a new peptide FITC-YT-16 to target PD-1. We have studied FITC-YT-16 by various experiments, including Molecular Operating Environment MOE modeling, purification testing by HPLC and LC mass, peptide/PD-1 conjugation and affinity by microscale thermophoresis (MST), and T cell immune-fluorescence imaging by fluorescence microscopy and flow cytometry. The peptide was tested for its ability to enhanceT cell activity against tumor cell lines, including TE-13, A549, and MDA-MB-231. Lastly, we assessed T cell cytotoxicity under peptide treatment. YT-16–PD-1 interaction showed a high binding affinity as a low energy complex that was confirmed by MOE. Furthermore, the peptide purity and molecular weights were 90.96% and 2344.66, respectively. MST revealed that FITC-YT-16 interacted with PD-1 at a Kd value of 17.8 ± 2.6 nM. T cell imaging and flow cytometry revealed high affinity of FITC-YT-16 to PD-1. Interestingly, FITC-YT-16 efficiently blocked PD-1 signaling pathways and promoted T cell inflammatory responses by elevating IL-2 and INF-γ levels. Moreover, FITC-YT-16 has the ability to activate T cell cytotoxicity. Therefore, FITC-YT-16 significantly enhanced T cell anti-tumor activity by blocking PD-1–PD-L1 interactions.

75P - Cemiplimab, a human PD-1 monoclonal antibody, in patients (pts) with recurrent or metastatic cervical cancer: Interim data from phase I cohorts

Background: For pts who progress after first-line platinum based therapy for recurrent/metastatic cervical cancer, there are no therapies available that have been demonstrated to improve survival or quality of life. Cemiplimab (REGN2810), a human monoclonal antibody to PD-1, exhibited encouraging efficacy and acceptable tolerability in a phase 1 dose escalation study. The present report focuses on interim data from the phase 1 cervical cancer expansion cohorts (ECs) of cemiplimab as a monotherapy (EC 23) or in combination with hypofractionated radiotherapy (hfRT) (EC 24) (NCT02383212). Methods: Pts with recurrent or metastatic cervical cancer resistant to or intolerant of platinum and taxane doublet therapy received cemiplimab 3 mg/kg Q2W IV for up to 48 weeks, in ECs 23 and 24, and hfRT (9 Gy x 3 times/week given 1 week after first dose of cemiplimab) in EC 24. The co-primary objectives were to evaluate the safety, tolerability, and efficacy of cemiplimab monotherapy or in combination with hfRT. Tumour response assessments (in non-irradiated target lesions) were performed by RECIST 1.1 Q8W. Results: As of 1 Sept, 2017, these ECs were fully enrolled with 20 pts (EC 23, n = 10, EC 24, n = 10). Median (range) age was 55.0 (31–76) years (EC 23) and 51.5 (29–65) years (EC 24). ECOG performance status 1 vs. 0 was 60% vs. 40% and 80% vs. 20%, respectively, for EC 23 and EC 24. Investigator-assessed overall response rate (ORR; complete response [CR] + partial response [PR]) was 10.0% (0 CR and 1 PR) in each of EC 23 and EC 24. At the time of data cut-off, both responses were ongoing with durations of 3.7+ months. The most common treatment-emergent adverse events (TEAEs) of any grade were diarrhoea (40.0%), fatigue, hypokalaemia and pain in extremity (each 30.0%) in EC 23, and diarrhoea and urinary tract infection (each 30.0%) in EC 24. There was no grade ≥3 TEAE reported in > 1 patient in either cohort. Conclusions: Cemiplimab as monotherapy and in combination with hfRT demonstrated antitumour activity with an acceptable safety profile in pts with metastatic or recurrent cervical cancer. Cemiplimab monotherapy vs. chemotherapy in ≥ 2nd line cervical cancer is currently being evaluated in a global randomised phase 3 study (NCT03257267). Editorial acknowledgement: Medical writing support under the direction of the authors was provided by Emmanuel Ogunnowo, PhD, of Prime (Knutsford, UK) and funded by Regeneron Pharmaceuticals, Inc. and Sanofi according to Good Publication Practice guidelines. Clinical trial identification: NCT02383212. Legal entity responsible for the study: Regeneron Pharmaceutical Inc. and Sanofi. Funding: Regeneron Pharmaceutical Inc. and Sanofi. Disclosure: D. Rischin: Research funding: Genentech/Roche, Merck, Amgen, Regeneron, Bristol-Myers Squibb. A. González-Martin: Consulting, advisory, speakers’ bureau, travel accommodation expenses: AstraZeneca, Tesaro, Roche, Pharmamar. J.Y. Hou: Consultant and fees: Foundation Medicine, Massive Bio, Inc. D. Cho: Consulting fees: Pfizer, BMS, Exelixis, Genentech, Prometheus. G. Falchook: Funding for trial for submitted work. S. Jabbour: Research funding grants: Merck, Nestle outside of the submitted work. K. Moore: KInstitutional consultancy (honorarium and ad board) fees: Tesaro, Genentech Roche, Clovis, AstraZeneca (for agents not involved in the SOLO-1 study), Immunogen, VBL Therapeutics, Janssen. M.G. Fury: Employee and shareholder: Regeneron Pharmaceuticals, Inc.; Patents, royalties, other intellectual property: Regeneron Pharmaceuticals, Inc. M. Feng: Employee and shareholder: Regeneron Pharmaceuticals, Inc., Bayer. J. Li: Employee and shareholder: Regeneron Pharmaceuticals, Inc., Novartis. I. Lowy: Employee, shareholder, fees for travel and accommodation expenses, leadership: Regeneron Pharmaceuticals, Inc. M. Mathias: Employee and shareholder: Regeneron Pharmaceuticals, Inc. All other authors have declared no conflicts of interest.

74P - Phase I expansion cohort results of cemiplimab, a human PD-1 monoclonal antibody, in combination with radiotherapy (RT), cyclophosphamide and GM-CSF, in patients (pts) with recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC)

74P - Phase I expansion cohort results of cemiplimab, a human PD-1 monoclonal antibody, in combination with radiotherapy (RT), cyclophosphamide and GM-CSF, in patients (pts) with recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC)