PD-L1 Checkpoint Inhibitors Research Articles

Abstract CT238: An open-label, phase 1 study of IDO inhibitor KHK2455 in combination with avelumab in adult subjects with locally advanced or metastatic urothelial carcinoma

Abstract Background: Indoleamine 2,3-dioxygenase 1 (IDO1) degrades tryptophan to kynurenine, suppressing T cell effector activity and increasing T regulatory cell activity. IDO1 expression is induced in some cancer cells and has been associated with suppression of effector T cell responses toward tumors. In nonclinical studies, IDO1 inhibition combined with other clinically established immune modulating agents (eg, anti-CTLA-4 or anti-PD-1 antibodies) showed a significant improvement in tumor growth suppression. KHK2455 is a long acting and selective IDO1 inhibitor under development as a new approach to enhance anti-tumor immunity. KHK2455 is being combined with different anti-cancer therapies to explore its ability to enhance anti-tumor immunity and overcome tumor immune evasion. Avelumab is a PD-L1 checkpoint inhibitor approved for treatment of urothelial carcinoma. This study represents an opportunity to assess the complementary action of KHK2455 IDO1 inhibition and avelumab checkpoint inhibition in the treatment of urothelial carcinoma. Methods: Study 2455-002 is a two-part, multicenter, open-label Phase 1 study of KHK2455 in combination with avelumab in adult subjects with locally advanced or metastatic urothelial carcinoma (including bladder, urethra, ureters, and renal pelvis), who are checkpoint inhibitor naїve and previously treated with platinum-based therapy. Part 1 (dose-escalation) has a 3+3 design to evaluate safety and tolerability and identify the maximum tolerated dose (MTD). Dose de-escalation based on dose limiting toxicities is permitted. Part 2 (cohort expansion) further explores the safety, pharmacokinetics, pharmacodynamics, and anti-tumor activity for the combination regimen at the MTD or highest tested dose. All subjects will receive oral KHK2455 at their assigned dose and avelumab IV. The primary study endpoints are safety and tolerability, and the secondary endpoints are efficacy (based on RECIST v1.1 criteria), pharmacokinetics, and immunogenicity. Exploratory endpoints include examination of pre and post treatment biopsies for intratumoral suppression of IDO1 activity to correlate peripheral and intratumoral suppression, along with pre and post treatment serum markers including, but not limited to, immune mediators and related cytokines. Descriptive statistics (n, mean, standard deviation, median, minimum, and maximum) for continuous variables and frequency distributions and percentages for discrete variables will be utilized. Approximately 44 subjects are planned for enrollment (12 subjects in Part 1 and 32 subjects in Part 2). Clinical trial information: NCT03915405 (sponsor: Kyowa Kirin Pharmaceutical Development, Inc.) Citation Format: Pratibha Desai, Santosh Rao, Yuta Ikawa, Barbara Kapelan, Sergey Efuni, Robert Latek, Takashi Sato, Denis Healy, Yousef Zakharia. An open-label, phase 1 study of IDO inhibitor KHK2455 in combination with avelumab in adult subjects with locally advanced or metastatic urothelial carcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT238.

Abstract CT044: Genomic correlates of clinical benefits from atezolizumab combined with bevacizumab vs. atezolizumab alone in patients with advanced hepatocellular carcinoma (HCC)

Abstract Background: Atezolizumab (atezo) and bevacizumab (bev) combination therapy has demonstrated robust clinical activity in patients with unresectable HCC who have not received prior systemic therapy (Lee et al., APPLE 2019; Cheng et al., ESMO Asia 2019). In this exploratory analysis, we aimed to identify tumor-based molecular biomarkers that may be associated with clinical response or resistance to atezo + bev. We also investigated how VEGF blockade with bev could potentiate PD-L1 checkpoint inhibition with atezo in pts with advanced HCC. Methods: Archival tumor tissues or fresh biopsies taken prior to treatment were collected from HCC pts enrolled in the Phase 1b trial GO30140 (NCT02715531). Arm A (n = 104) was a single-arm evaluation of atezo + bev; Arm F (n = 119) was a randomized arm comparing atezo + bev with atezo. Whole-exome sequencing was carried out on these tumor tissues to determine tumor mutation burden (TMB). Gene expression in tumors was profiled by RNAseq analysis. The association between biomarker expression and clinical response (responders [R] vs. non-responders [NR]) or PFS was assessed by t-tests or Cox regression models, respectively. All p-values are descriptive. Results: In Arm A, 90/104 pts were biomarker evaluable. TMB was not associated with response to atezo + bev or PFS. In contrast, analysis of baseline tumor gene expression showed that pre-existing immunity appeared to be associated with clinical response and longer PFS, which included high expression of CD274 (PD-L1) (R vs. NR, p < 2.1 × 10−5; PFS: HR = 0.42 [0.25-0.72]), and T effector signature (GZMB, PRF1, CXCL9) (R vs. NR, p < 0.0004; PFS: HR = 0.46 [0.27-0.78]). Gene expression related to Notch pathway activation (i.e. high expression of HES1) appeared to be associated with lack of response to atezo + bev (p < 0.039) and shorter PFS (HR = 2.1 [1.3-3.6]). In Arm F, 91/119 pts were biomarker evaluable. High expression of VEGF receptor 2 (VEGFR2; HR = 0.36 [0.16-0.81]), Treg (HR = 0.35 [0.15-0.82]), myeloid inflammation (HR = 0.43 [0.19-0.95]), and TREM1/MDSC signatures (HR = 0.43 [0.19-0.94]) was associated with longer PFS in patients treated with atezo + bev than in those treated with atezo alone. Analysis of 12 serial biopsy pairs confirmed reduced levels of VEGFR2 and Treg signatures after atezo + bev treatment. Conclusion: We identified candidate biomarkers for predicting response to atezo + bev in HCC. Furthermore, the findings in Arm F are consistent with previous preclinical studies supporting a multi-faceted role of VEGF/VEGFR signaling in promoting immune suppression in addition to angiogenesis. Overall, the data presented here further support the mechanistic hypotheses on how anti-VEGF may combine with immune checkpoint blockade to increase its clinical benefit. As these results are exploratory, future study is needed to confirm these findings in a larger population. Citation Format: Andrew X. Zhu, Yinghui Guan, Alexander R. Abbas, Hartmut Koeppen, Shan Lu, Chih-Hung Hsu, Kyung-Hun Lee, Michael S. Lee, Aiwu Ruth He, Amit Mahipal, Beiying Ding, Jessica Spahn, Wendy Verret, Baek-Yeol Ryoo, Yulei Wang. Genomic correlates of clinical benefits from atezolizumab combined with bevacizumab vs. atezolizumab alone in patients with advanced hepatocellular carcinoma (HCC) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT044.

75. PROGRAMMED DEATH RECEPTOR LIGAND ONE EXPRESSION MAY INDEPENDENTLY PREDICT SURVIVAL IN NON-SMALL CELL LUNG CARCINOMA BRAIN METASTASES PATIENTS RECEIVING IMMUNOTHERAPY

BACKGROUNDProgrammed death receptor ligand one (PD-L1) expression is known to predict response to PD-1/PD-L1 inhibitors in non-small cell lung cancer (NSCLC). However, the predictive role of this biomarker in brain metastases (BMs) is unknown. The aim of this study was to assess whether PD-L1 expression predicts survival in patients with NSCLC BMs treated with PD-1/PD-L1 inhibitors, after adjusting for established prognostic models.METHODSIn this multi-institutional retrospective cohort study, we identified NSCLC-BM patients treated with PD-1/PD-L1 inhibitors after local BM treatment (radiotherapy or neurosurgery) but before intracranial progression. Cox proportional hazards models were used to assess predictive value PD-L1 expression for overall survival (OS) and intracranial progression free survival (IC-PFS).RESULTSForty-eight BM patients with available PD-L1 expression were identified. PD-L1 expression was positive in 33 patients (69%). Median survival was 26 months. In univariable analysis, PD-L1 predicted favorable OS (HR = 0.44; 95% CI 0.19 – 1.02; p = 0.055). This effect persisted after correcting for lung-graded prognostic assessment (lung-GPA) and other identified potential confounders (HR = 0.24; 95% CI = 0.10 – 0.61; p = 0.002). Moreover, when modeled as a continuous variable, there appeared to be a proportional relationship between percentage of PD-L1 expression and survival (HR = 0.86 per 10% expression, 95% CI 0.77 – 0.98, p = 0.02). In contrast, PD-L1 expression did not predict IC-PFS in uni- or multivariable analysis (adjusted HR = 0.54, 95% CI 0.26 – 1.14, p = 0.11).CONCLUSIONSIn patients with NSCLC-BMs treated with PD-1/PD-L1 checkpoint inhibitors and local treatment, PD-L1 expression may predict OS independent of lung-GPA. IC-PFS did not show association with PD-L1 expression, although the present analysis may lack power to assess this. Larger studies are required to validate these findings.

Elucidation of S-Allylcysteine Role in Inducing Apoptosis by Inhibiting PD-L1 Expression in Human Lung Cancer Cells.

The aim of this study is to explore the therapeutic potential of S-allylcysteine (SAC) organosulphur compound as a potent immune checkpoint inhibitor PD-L1. Natural compounds have been showing tremendous anticancerous potential via suppressing the expression of genes involved in the development and progression of several carcinomas. This has further motivated us to explore the therapeutic potential of organosulphur compounds as potent immune checkpoint inhibitors. Our study was designed to elucidate the potential of S-allylcysteine (SAC) as significant PD-L1 (immune checkpoint) inhibitor in human lung cancer A549 cancer cell line by using both the in vitro and in silico approaches. Anticancerous effect of the SAC on lung cancer cells was determined by using the MTT cell viability. Apoptotic induction was confirmed by Hoechst staining, percent caspase-3 activity as well as gene expression analysis by real time PCR. Reactive Oxygen Species (ROS) was estimated by DCFDA method. Additionally, ligand-target protein interaction was analysed by molecular docking. Cell growth and proliferation was significantly reduced in SAC treated A549 cells in a concentration and time.dependent manner. The effect of SAC on apoptotic induction was analyzed by enhanced nuclear condensation, increased percent caspase-3 activity as well as modulation of apoptotic genes. Furthermore, SAC treatment also resulted in reduced expression of PD-L1 and HIF-1α. Additionally, in silico analysis also supported the in vitro findings by showing efficient docking with PD-L1 immune checkpoint target. Therefore, our results clearly suggested that SAC could serve as a novel chemotherapeutic candidate for the treatment of lung cancer by inhibiting immune checkpoint target PD-L1 in human lung cancer cells. Additionally, our study also explained a novel molecular mechanism of its antitumor activity.

Silibinin down-regulates PD-L1 expression in nasopharyngeal carcinoma by interfering with tumor cell glycolytic metabolism

The upregulation of checkpoint inhibitor PD-L1 expression has recently been associated with nasopharyngeal carcinoma (NPC) resistance to therapy. The mechanism of induction of PD-L1 has also been linked to enhanced aerobic glycolysis promoted by HIF1-α dysregulation and LDH-A activity in cancer. Here, we investigated the effect of the anti-tumoral compound Silibinin on HIF-1α/LDH-A mediated cancer cell metabolism and PD-L1 expression in NPC. Our results demonstrate that exposure to Silibinin potently inhibits tumor growth and promotes a shift from aerobic glycolysis toward oxidative phosphorylation. The EBV + NPC cell line C666-1 and glycolytic human tumor explants treated with Silibinin displayed a reduction in LDH-A activity which consistently associated with a reduction in lactate levels. This effect was accompanied by an increase in intracellular citrate levels in C666-1 cells. Accordingly, expression of HIF-1α, a critical regulator of glycolysis, was down-regulated after treatment. This event associated with a down-regulation in PD-L1. Altogether, our results provide evidence that silibinin can alter PD-L1 expression by interfering with HIF-1α/LDH-A mediated cell metabolism in NPC. These results provide a new perspective for Silibinin use to overcome PD-L1 mediated NPC resistance to therapy.

Cytokine Storm in COVID-19: The Current Evidence and Treatment Strategies.

Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) is the pathogen that causes coronavirus disease 2019 (COVID-19). As of 25 May 2020, the outbreak of COVID-19 has caused 347,192 deaths around the world. The current evidence showed that severely ill patients tend to have a high concentration of pro-inflammatory cytokines, such as interleukin (IL)-6, compared to those who are moderately ill. The high level of cytokines also indicates a poor prognosis in COVID-19. Besides, excessive infiltration of pro-inflammatory cells, mainly involving macrophages and T-helper 17 cells, has been found in lung tissues of patients with COVID-19 by postmortem examination. Recently, increasing studies indicate that the “cytokine storm” may contribute to the mortality of COVID-19. Here, we summarize the clinical and pathologic features of the cytokine storm in COVID-19. Our review shows that SARS-Cov-2 selectively induces a high level of IL-6 and results in the exhaustion of lymphocytes. The current evidence indicates that tocilizumab, an IL-6 inhibitor, is relatively effective and safe. Besides, corticosteroids, programmed cell death protein (PD)-1/PD-L1 checkpoint inhibition, cytokine-adsorption devices, intravenous immunoglobulin, and antimalarial agents could be potentially useful and reliable approaches to counteract cytokine storm in COVID-19 patients.

Late immune-related adverse events in long-term responders to PD-1/PD-L1 checkpoint inhibitors: A multicentre study

BackgroundData on spectrum and grade of immune-related adverse events (irAEs) in long-term responders to immune checkpoint inhibitors (ICIs) are lacking. MethodsWe performed a retrospective multicenter study to characterized irAEs occurring after a 12-months minimum treatment period with PD-(L)1 ICIs in patients with advanced cancer. IrAEs were categorized into ‘early’ (≤12 months) and ‘late’ (>12 months). ResultsFrom September 2013 to October 2019, 436 consecutive patients were evaluated. Two hundred twenty-three experienced any grade early-irAEs (51.1%), whereas 132 experienced any grade late-irAEs (30.3%) (p < 0.0001). Among the latter, 29 (22%) experienced a recurrence of an early-irAEs, whereas 103 (78%) experienced de novo late-irAEs involving different system/organ. Among patients with late-irAEs, 21 experienced GIII/GIV irAEs (4.8%). Median time to onset of early-irAEs was 3.4 months (95% confidence interval [CI]: 2.8–4.2), whereas the median time to onset of late-irAEs was 16.6 months (95% CI: 15.8–17.6). Cumulative time-adjusted risk of disease progression according to both the early-irAEs (hazard ratio [HR] = 0.63 [95% CI: 0.30–1.29], p = 0.204) and late-irAEs occurrence revealed no statistically significant differences (HR = 0.75 [95% CI: 0.37–1.56], p = 0.452). In addition, the time-adjusted cumulative risk of death in accordance with both early-irAEs (HR = 0.79 [95% CI: 0.34–1.86], p = 0.598) and late-irAEs (HR = 0.92 [95% CI: 0.49–1.74], p = 0.811) did not show statistically significant differences. ConclusionAlthough less frequent than early-irAEs, late-irAEs are quite common in long responders to PD-(L)1 ICIs and are different in terms of spectrum and grade. Time-adjusted analysis revealed that the cumulative risk of disease progression and death were not significantly reduced in patients who experienced late-irAEs.

Clinicogenomic predictors of extreme responses to anti-PD1/PDL1 checkpoint inhibitors (CPI) in metastatic urothelial cancer (mUC).

5050 Background: Only a subset of mUC patients (pts) derives benefit from CPI. We sought to evaluate potential clinical and genomic predictors, with additional focus on extreme outcomes. Methods: CPI-treated mUC with tumor sequencing with MSK-IMPACT (up to 468 genes) were identified. Pre-CPI clinical variables (including hemoglobin [hgb], lymphocyte [lymph], neutrophil [neut] and eosinophil [eos] counts) were extracted. Endpoint was time on treatment (ToT). Poor responders were defined as ToT ≤9 weeks and overall survival ≤3 months; exceptional responders had ToT &gt;20 months. A multivariate Cox model for ToT was performed with clinical variables chosen by stepwise selection minimizing Akaike information criterion. Genomic analyses were adjusted for multiple testing. Results: 166/171 identified mUC were evaluable. Median age was 68 years, 78% were male. 72% had bladder primary, while 17%, 35% and 28% had liver, lung and bone metastases (mets). 67% had prior platinum chemo. 24 pts (14%) were poor and exceptional responders, respectively. In univariate analysis, liver mets were associated with shorter ToT while DNA damage repair (DDR) gene alterations, higher body mass index (BMI), eos, hgb and tumor mutation burden (TMB) were associated with longer ToT. No specific genomic alterations achieved q&lt;.05. In multivariate model, prior chemo (HR 1.6, p=.01), liver mets (HR 2.4, p&lt;.01) and high neut were associated with shorter ToT while urethral primary (HR 0.1, p&lt;.01), higher TMB (HR 0.9, p&lt;.01) and higher eos (HR 0.1, p&lt;.01) were independently associated with ToT. Univariate logistic regression to identify poor and exceptional responders are tabulated. Multivariate results will be reported. Conclusions: In addition to validation of various known mUC prognosticators, we observed potential non-linear influence of clinical and genomic factors on extreme outcomes. [Table: see text]

Comparative quantitative safety profiles of PD-1 and PD-L1 checkpoint inhibitor monotherapies: A Bayesian model-based meta-analysis.

e15167 Background: Anti-cancer therapies with immune checkpoint inhibitors (ICIs) are associated with immune-mediated adverse events (imAEs). The objective of this study was to use a Bayesian model-based meta-analysis, to compare safety profiles of PD-1 and PD-L1 checkpoint inhibitor monotherapies. Methods: We performed an exhaustive search through PubMed and TrialTrove databases, ASCO and ESMO abstracts to identify relevant ICI safety data. A Bayesian meta-analysis (BMA) was performed for all-grade and high-grade (Grades 3-4) treatment-related AEs (trAEs) and immune-mediated AEs (imAEs). The analysis was performed for total AEs and individual AEs affecting different organs: dermatological (rash, pruritus), gastrointestinal (diarrhea, colitis), hepatic (AST, ALT), respiratory (pneumonitis), and endocrine (hyperthyroidism, hypothyroidism). Software STAN along with the brms package in R software were used for the BMA. Results: A total of 145 articles were identified, covering 30,737 patients in 153 cohorts treated with anti PD-1 and anti PD-L1 monotherapies. For total all-grade and grade 3&amp;4 trAEs, anti PD-L1 demonstrated lower AE rates vs. anti PD-1 (65% vs. 69% and 12% vs. 16%, respectively). Results were similar for total all-grade and high-grade imAEs (19% vs. 26% and 4% vs. 7%, respectively). The analysis of all-grade individual trAEs showed that anti PD-L1 exhibited lower AE rates vs. anti PD-1 for rash (8% vs. 10.5%), pruritus (9% vs. 12%), diarrhea (8.5% vs. 11%), colitis (1.0% vs. 1.6%), AST (3.0% vs. 5.5%), ALT (3.5% vs. 5.6%), pneumonitis (3.0% vs. 3.9%), hyperthyroidism (0.8% vs. 4.0%) and hypothyroidism (6.0% vs. 8.0%). For grade 3&amp;4 trAEs, differences between anti PD-L1 and anti PD-1 were: 0.6% vs. 1.3% for diarrhea, 0.7% vs. 1.4% for colitis, and 0.9% vs 1.6% for pneumonitis. All-grade imAEs were less frequent for anti PD-L1 vs. anti PD-1 for: rash (6.5% vs. 10%), colitis (1.0% vs. 2.0%), AST (3.5% vs. 3.9%), ALT (2.9% vs. 4.0%), pneumonitis (2.0% vs. 4.0%), hyperthyroidism (2.5% vs. 4.0%) and hypothyroidism (5.5% vs. 9.0%). Similar results were obtained for grade 3&amp;4 imAEs incidences: rash (0.5% vs. 0.9%), diarrhea (0.5% vs. 1.5%), colitis (0.5% vs. 1.1%) and pneumonitis (0.9% vs. 1.4%). Conclusions: Significant differences in trAEs and imAEs rates were shown for anti PD-L1 vs. anti PD-1 monotherapies. Anti PD-L1 demonstrated more favorable safety profiles for total and individual AE rates. Notably, AE rates for pneumonitis and colitis were twice as high for anti PD-1 vs. anti PD-L1 therapies.

PARP and PD-1/PD-L1 checkpoint inhibition in recurrent or metastatic endometrial cancer.

The prognosis of recurrent or metastatic endometrial cancer is poor, with five-year survival of only 10-20 %. First-line therapy consists of either platinum-based chemotherapy or hormonal therapy. No standard subsequent-line therapy has been identified. In recent years, significant progress has been made in the knowledge on underlying molecular biology of endometrial cancer and potential targets for therapy have been identified. Targeted therapies as poly (ADP-ribose) polymerase (PARP) inhibitors and immunotherapy as PD-1/PD-L1 checkpoint inhibitors have the potential to be effective against specific subtypes of endometrial cancer. Preclinical studies have shown that combining these agents may result in a synergistic effect. In this review, we focus on the molecular basis of checkpoint inhibition and targeted therapy as PARP inhibition in endometrial cancer and summarize available clinical data, and ongoing and planned clinical trials that investigate these agents as mono- or combination therapies in endometrial cancer and where relevant, other gynecological cancers.

Predominance of Central Memory T Cells with High T-Cell Receptor Repertoire Diversity is Associated with Response to PD-1/PD-L1 Inhibition in Merkel Cell Carcinoma.

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer, which can be effectively controlled by immunotherapy with PD-1/PD-L1 checkpoint inhibitors. However, a significant proportion of patients are characterized by primary therapy resistance. Predictive biomarkers for response to immunotherapy are lacking. We applied Bayesian inference analyses on 41 patients with MCC testing various clinical and biomolecular characteristics to predict treatment response. Further, we performed a comprehensive analysis of tumor tissue-based immunologic parameters including multiplexed immunofluorescence for T-cell activation and differentiation markers, expression of immune-related genes and T-cell receptor (TCR) repertoire analyses in 18 patients, seven objective responders, and 11 nonresponders. Bayesian inference analyses demonstrated that among currently discussed biomarkers only unimpaired overall performance status and absence of immunosuppression were associated with response to therapy. However, in responders, a predominance of central memory T cells and expression of genes associated with lymphocyte attraction and activation was evident. In addition, TCR repertoire usage of tumor-infiltrating lymphocytes (TILs) demonstrated low T-cell clonality, but high TCR diversity in responding patients. In nonresponders, terminally differentiated effector T cells with a constrained TCR repertoire prevailed. Sequential analyses of tumor tissue obtained during immunotherapy revealed a more pronounced and diverse clonal expansion of TILs in responders indicating an impaired proliferative capacity among TILs of nonresponders upon checkpoint blockade. Our explorative study identified new tumor tissue-based molecular characteristics associated with response to anti-PD-1/PD-L1 therapy in MCC. These observations warrant further investigations in larger patient cohorts to confirm their potential value as predictive markers.

Pharmacokinetics and Systems Pharmacology of Anti-CD47 Macrophage Immune Checkpoint Inhibitor Hu5F9-G4

Background: Hu5F9-G4, a human immunoglobulin G4 (IgG4) monoclonal antibody (mAb) has recently been granted fast-track designation by the FDA for the treatment of relapsed or refractory diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma. Hu5F9-G4 has the ability to block CD47-SIRPα signaling along with anti- EGFR and anti-PD-L1 immune checkpoint activity that is involved in a variety of cancers like solid tumors, Non-Hodgkin’s Lymphoma (NHL), colorectal cancer (CRC), breast, ovarian and bladder cancers, and hematological malignancies. Thus, Hu5F9-G4 is an important biologic that has increasing clinical relevance in cancer care. Methods: We queried PubMed, Web of Science, Google Scholar, Science Direct and Scopus databases with keywords pertaining to Hu5F9-G4. In addition, we have included the Hu5F9-G4 data presented at the 60th American Society of Hematology (ASH) Annual Meeting, the American Society of Clinical Oncology (ASCO) Annual Meeting and 23rd Congress of the European Hematology Association (EHA). Results: We discuss the mechanistic basis and preclinical evidence for the anticancer activity of Hu5F9-G4. Further, we delineate clinical studies, alone and in combination with anti-CD20 mAb rituximab, anti-EGFR mAb cetuximab, PD-L1 checkpoint inhibitors avelumab and atezolizumab, and anti-HER2 mAb trastuzumab. Moreover, the potential adverse effects, pharmacokinetics, and pharmacodynamics of Hu5F9-G4 with emphasis on the role of CD47-SIRPα signaling in phagocytosis are presented. Conclusions: Taken together, we review the pharmacokinetics and systems pharmacology of Hu5F9-G4 which appears to hold great promise for the future of cancer care.

Abstract B26: Tumor reduction by a small molecule human PD-1/PD-L1 inhibitor in a melanoma/PBMC co-implantation model

Abstract Introduction: FDA-approved antibody-based therapies targeting the Programmed cell Death-1/Programmed Death-Ligand 1 (PD-1/PD-L1) immune checkpoint axis have gained considerable attention and success in cancer immunotherapy recently. As a next-generation therapy, small-molecule PD-1/PD-L1 checkpoint inhibitors may provide the potential for increased tumor penetration, shorter half-life (to better manage immune related adverse events), and lower cost of goods. We embarked on an effort to identify and develop small molecules capable of targeting the immune checkpoint molecules PD-1/PD-L1, with an aim to improve anticancer immune responses in vivo. Methods: Co-crystallized human PD-1/PD-L1 provided structural information from which we developed a number of small-molecule checkpoint inhibitors. Active compounds were first profiled by an ELISA assay measuring inhibition of the PD-1/PD-L1 interaction, followed by functional cell-based reporter and mixed lymphocyte reaction (MLR) assays. PD-1/PD-L1 inhibitory compounds thus identified were further selected for in vivo model testing. Since our human-specific PD-1/PD-L1 inhibitors did not cross-react with murine PD-1/PD-L1, we co-implanted A375 human melanoma cells along with human peripheral blood mononuclear cells (PBMCs) into immunodeficient NOD/SCID mice to test their efficacy in vivo. Results: The optimized human PD-1/PD-L1 inhibitors exhibited marked activities in both the cell-based reporter and MLR assays. Moreover, lead compound CCX4503 reduced tumor growth in vivo to a similar extent as the positive control anti-human PD-L1 antibody. Antitumor activity was completely dependent on the presence of human PBMCs. The tumor microenvironment analysis by flow cytometry indicated that the antitumor activity of CCX4503 was accompanied by a significantly higher CD8+ T-Cell/CD4+ T-cell ratio. An X-ray structure of CCX4503 co-crystallized with PD-L1 revealed several vital interactions within the PD-1-binding-region of PD-L1, providing information about the structural basis by which the compound disrupts the PD-1/PD-L1 immune checkpoint interaction. Summary: We have identified and advanced unique small-molecule inhibitors of human PD-1/PD-L1 by rational design. Molecules resulting from these efforts, such as CCX4503, exhibited marked inhibition of the PD-1/PD-L1 interaction and signaling in vitro, and also clear antitumor effects in an animal model system in vivo. Citation Format: Marta Vilalta, Sreenivas Punna, Shijie “Chris” Li, Viengkham Malathong, Christopher Lange, Darren McMurtrie, Ju Yang, Howard Roth, Jeffrey McMahon, James J. Campbell, Linda S. Ertl, Ryan Ong, Yu Wang, Niky Zhao, Vicky Chhina, Alice Kumamoto, Simon Yau, Tong Dang, Penglie Zhang, Thomas J. Schall, Rajinder Singh. Tumor reduction by a small molecule human PD-1/PD-L1 inhibitor in a melanoma/PBMC co-implantation model [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B26.

Age-Related Tumor Immune Microenvironment Differences in Patients with Squamous Cell Carcinoma of the Oral Tongue

Squamous cell carcinoma (SCC) is the most common malignancy of the oral tongue, usually affecting older patents, but occasionally also patients younger than 40 years old, mostly women. No genomic differences have been reported in the different age groups, but little is known about the tumor immune microenvironment. We performed an exploratory analysis for potential age-related differences in the tumor inflammation signature (TIS), which can be predictive for potential responders to PD-1 / PD-L1 checkpoint inhibitors in a variety of cancer patients.

Integration of Immunotherapy Into the Treatment of Advanced Urothelial Carcinoma

Five new PD-1/PD-L1 checkpoint inhibitors have been approved for the treatment of metastatic urothelial carcinoma (UC): pembrolizumab, atezolizumab, durvalumab, nivolumab, and avelumab. Although cisplatin-based chemotherapy remains the recommended frontline option for cisplatin-eligible patients with metastatic UC, immunotherapy is now an available option in the second-line setting as well as the frontline setting for selected cisplatin-ineligible patients who are either unable to tolerate chemotherapy or PD-L1-positive. This review describes the updated clinical efficacy of these checkpoint inhibitors in the treatment of advanced UC and suggests how they can be sequenced in the context of available chemotherapeutic options.

Current Understanding of the Mechanisms Underlying Immune Evasion From PD-1/PD-L1 Immune Checkpoint Blockade in Head and Neck Cancer.

Starting in 2014, large phase III clinical trials began to disclose the study results of using programmed death (PD)-1 immune checkpoint inhibitors (ICIs) (pembrolizumab, nivolumab) and PD-ligand (L)1 (atezolizumab, durvalumab, avelumab) ICIs immunotherapy in patients with advanced head and neck squamous cell carcinoma (HNSCC). In the recurrent and metastatic (R/M), cisplatin-refractory setting, nivolumab achieved a 2.2-fold increase of the median 1-year overall survival as compared with investigators' choice of salvage chemotherapy (36.0 vs. 16.6%). A paradigm shift to the winning regimen, pembrolizumab combined with platinum and infusional fluorouracil, has outperformed the past gold standard of cetuximab-based platinum and fluorouracil combination in terms of overall survival (median, 13.6 vs. 10.1 mo) when administered as the first-line treatment for R/M HNSCC. Nevertheless, many patients still did not respond to the PD-1/PD-L1 checkpoint inhibitor treatment, indicating innate, adapted, or quickly acquired resistance to the immunotherapy. The mechanisms of resistance to ICIs targeting the PD-1/PD-L1 signaling pathway in the context of HNSCC are the focus of this review. The past 5 years have seen improved understanding of the mechanisms underlying checkpoint inhibition resistance in tumor cells, such as: tumor cell adaption with malfunction of the antigen-presenting machinery via class I human leukocyte antigen (HLA), reintroduction of cyclin D–cyclin-dependent kinase (CDK) 4 complex to cell cycles, enrichment of CD44+ cancer stem-like cells, or development of inactivating mutation in IKZF1 gene; impairment of T-cell functions and proliferation through mutations in the interferon-γ-regulating genes, suppression of the stimulator of interferon genes (STING) pathway, or resulted from constitutional nutritional iron deficiency state; metabolic reprogramming by cancer cells with changes in metabolites such as GTP cyclohydrolase 1, tetrahydrobiopterin, kynurenine, indoleamine 2,3-dioxygenase, and arginase 1; defective dendritic cells, CD-69 sufficient state; and the upregulation or activation of the alternative immune checkpoints, including lymphocyte activation gene-3 (LAG3), T-cell immunoglobulin and ITIM domain (TIGIT)/CD155 pathway, T-cell immunoglobulin mucin-3 (TIM-3), and V domain-containing Ig suppressor of T-cell activation (VISTA). Several potential biomarkers or biosignatures, which could predict the response or resistance to the PD-1/PD-L1 checkpoint immunotherapy, are also discussed.

Microsatellite instability (MSI-H) in metastatic urothelial carcinoma (mUC): A biomarker of divergent responses to systemic therapy.

566 Background: MSI frequently arises from deficiencies in mismatch repair mechanisms (dMMR) and are associated with higher response rates to anti-PD1/PDL1 checkpoint inhibitors (CPI) in different cancer types, including mUC (Iyer et al, ASCO 2017). Here, we sought to (1) assess the platinum-based chemotherapy response in MSI-H mUC, and (2) present an updated analysis of CPI response in MSI-H mUC from a database of &gt; 1000 sequenced UC. Methods: From an institutional database of UC tumors genomically characterized using the MSK-IMPACT assay, we identified tumors with high MSIsensor score &gt; 10 (MSI-H) for in-depth analysis. MSIsensor has been shown to correlate strongly with MSI status (Middha et al, JCO Precis Oncol 2017). Patient and disease characteristics, as well as response to (1) platinum-based chemotherapy and (2) CPI were analyzed. Results: A total of 1,333 UC from 1,194 pts were sequenced. 26 pts (2%) had an MSI score &gt; 10. Of these, 20 (77%) were male, 17 (65%) were current or former smokers, and 20 (77%) had upper tract UC. 23/26 pts had alterations in MMR genes (MSH2, n = 15; MLH1, n = 6; MSH6 and PMS2, n = 1), 18 of which underwent germline testing which was positive in 14 cases (78%). 10/26 MSI-H patients developed metastatic UC. Six received first-line platinum-based chemotherapy with median PFS of 2.6 months, four with primary progressive disease. Ten patients received CPI in the mUC setting, two of them in combination with non-CTLA4 agents, six as second or third-line therapies, two following recurrence of disease within 12 months of peri-operative chemotherapy, and two as first line therapy. With a median follow-up of 24.3 months, PFS rate was 90% and 77% at 12 and 24 months, respectively, with near-complete or complete response in 9 patients. Conclusions: MSI-H status in UC predicts deep and durable responses to CPI and is associated with inferior chemotherapy responses. CPI should be considered for first-line treatment in this subset of patients. Pts with somatic MSI-H bladder or upper tract UC should be offered genetic testing for Lynch syndrome.

Abstract P5-04-02: Safety and efficacy from first-in-human immunotherapy combining NK and T cell activation with off-the-shelf high-affinity CD16 NK cell line (haNK) in patients with 2nd-line or greater metastatic triple-negative breast cancer (TNBC)

Abstract TNBC is an aggressive subtype of breast cancer with limited treatment options. We hypothesize that effective response against TNBC requires a coordinated approach that orchestrates both the innate and adaptive immune system. We further hypothesize that by orchestrating the activation of the entire immune system, we could accomplish immunogenic cell death with durable responses in this disease. We describe a first-in-human novel combination immunotherapy protocol of chemoradiation, cytokine-induced NK and T cell activation, checkpoint inhibition, and off-the-shelf high-affinity NK cell infusion. We instituted this first in human immunotherapy protocol consisting of low-dose metronomic chemoradiation therapy, combined with a novel IgG1 Fc-engineered IL-15-complexed protein (N803), adenoviral and yeast tumor-associated antigen vaccines (MUC1, brachyury, CEA), followed by off-the-shelf high-affinity NK cells (haNK), and a PD-L1 checkpoint inhibitor. A phase 1b trial in pts with metastatic TNBC was initiated in 9 pts, 8 of whom had relapsed after two or more lines of prior therapy (3rd-line). All pts received this combination therapy instituted over a three-week cycle as outpatients. Safety was assessed and efficacy assessment is ongoing. Nine pts have been treated to date in an outpatient setting. All pts had at least 1 grade ≥3 TRAE, primarily chemotherapy-related neutropenia or anemia. Grade ≥3 haNK-related AEs (fever and fatigue) were observed in 2 subjects. No SAEs were attributed to investigational agents. No pts experienced cytokine release syndrome. To date, early efficacy results are as follows: a disease control rate (CR+PR+SD) of 78% (7/9 pts); ORR (PR+CR) of 56% (5/9 pts). Two pts (22%; 2/9) achieved a complete response (CR). To date, median follow up time is 301 days. 7 pts are alive, and the duration of response ranges from 2 mo to over 12 mo. In pts with CR or PR, peripheral blood (PB) analysis showed &amp;gt;13x increase in TCR diversity at 2 mo after initial treatment with increasing overall diversity thereafter; conversely, in pts with SD, PB TCR diversity increased &amp;lt;2x or decreased. Four patients remain on study. This first in human clinical trial of combination chemoradiation, cytokine fusion protein, NK cell therapy, and a checkpoint inhibitor demonstrated a safe and tolerable immunotherapy protocol. Early efficacy data is encouraging with a 78% disease control rate, 56% ORR and 22% (2/9) CR in pts with metastatic TNBC, 2nd-line or greater. Citation Format: Mira Kistler, Chaitali Nangia, Christina To, Lennie Sender, John Lee, Frank Jones, Omid Jafari, Tara Seery, Shahrooz Rabizadeh, Kayvan Niazi, Amy Rock, Patrick Soon-Shiong. Safety and efficacy from first-in-human immunotherapy combining NK and T cell activation with off-the-shelf high-affinity CD16 NK cell line (haNK) in patients with 2nd-line or greater metastatic triple-negative breast cancer (TNBC) [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-04-02.

Abstract P3-05-09: mRNA expression level and prognostic significance of different immune-related biomarkers in early breast cancer

Abstract Background: The combination of an anti-Programmed Cell Death-Ligand-1 (anti-PD-L1) agent, atezolizumab, plus chemotherapy (CT) as first line treatment in triple negative (TN) advanced breast cancer (ABC), resulted into a significant improvement in Progression Free Survival (PFS) as compared to Nab-paclitaxel alone, and a significant improvement in Overall Survival (OS) in the PD-L-1 positive subgroup (&amp;gt; 1% by IHC). With these results, the IMpassion 130 study met its primary endpoint, although its impact on the prognosis of TN ABC is less than expected, suggesting that innovative approaches are needed to maximize the role of immunotherapy in this disease subset. In this perspective, the potential role of addressing innate immunity as opposed to adaptive immunity has not yet been evaluated. It has been shown that Tumor-Associated Macrophages (TAMs) may express the immune checkpoint inhibitor PD-L1, thus contributing to immunosuppression. In addition, in response to microenvironmental signals they acquire a tumor-promoting M2-like phenotype, that supports angiogenesis, tissue remodeling and metastasis formation. They also express the Signal-regulatory protein (SIRPα) which provides a “don’t eat” me signal that impairs phagocytosis of CD47 positive cancer cells. CD47 is expressed in all human solid tumor cells; its role is to protect cancer cells from being recognized by innate immune surveillance. With these premises, the aim of this study is to evaluate the expression and prognostic value of different biomarkers related to innate and adaptive immunity, by using publicy available gene expression datasets, to assess if double immune co-targeting (i.e. innate and adaptive) might represent a viable strategy to optimise immunotherapy in ABC. Methods: We used previously published gene expression datasets by two online tools: GOBO and GEPIA. GOBO is an ultrafast tool including 1881 early BC patients generated on Affymetrix U133A microarrays, with a median follow up of 120 months. Expression of CD47, SIRP, CD163 and CD204 (M2-like phenotype) mRNA were evaluated as continuous variables. Kaplan Meier survival curves were used to assess the prognostic ability of the identified biomarkers. GEPIA is a web server for analysing the RNA sequencing expression data of tumours and normal samples from the TCGA and the GTEx projects, by a standard processing pipeline. Results: CD47 and CD204 mRNAs were significantly overexpressed in BC samples with respect to normal tissues (p &amp;lt; 0.05). Furthermore, CD47, SIRPalpha and CD163 were differentially modulated in the different BC subtypes (p&amp;lt;0.00001), showing an increased expression in the basal like group. Finally, the expression of mRNA CD47, SIRPa and CD163 were associated with a significanly worse OS only in the luminal A subtype (p&amp;lt;0.008, p&amp;lt;0.05 and p&amp;lt;0.01, respectively). Conclusions: These results indicate that innate immunity is involved in BC prognosis, and might be considered a target for therapy, in particular in those subtypes such as the Luminal A group, characterised by a favourable outcome; conversely, no effect was observed in subtypes characterised by a worse prognosis such as the basal-like tumors. Further investigation on the role of innate immunity in BC is warranted. Citation Format: Veronica Martini, Francesco Favero, Davide Corà, Feba Varughese, Antonio Sica, Alessandra Gennari. mRNA expression level and prognostic significance of different immune-related biomarkers in early breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-05-09.

Weighing the role of skeletal muscle mass and muscle density in cancer patients receiving PD-1/PD-L1 checkpoint inhibitors: a multicenter real-life study

Sarcopenia represents one of the hallmarks of all chronic diseases, including cancer, and was already investigated as a prognostic marker in the pre-immunotherapy era. Sarcopenia can be evaluated using cross-sectional image analysis of CT-scans, at the level of the third lumbar vertebra (L3), to estimate the skeletal muscle index (SMI), a surrogate of skeletal muscle mass, and to evaluate the skeletal muscle density (SMD). We performed a retrospective analysis of consecutive advanced cancer patient treated with PD-1/PD-L1 checkpoint inhibitors. Baseline SMI and SMD were evaluated and optimal cut-offs for survival, according to sex and BMI (+/−25) were computed. The evaluated clinical outcomes were: objective response rate (ORR), immune-related adverse events (irAEs), progression free survival (PFS) and overall survival (OS). From April 2015 to April 2019, 100 consecutive advanced cancer patients were evaluated. 50 (50%) patients had a baseline low SMI, while 51 (51%) had a baseline low SMD according to the established cut offs. We found a significant association between SMI and ECOG-PS (p = 0.0324), while no correlations were found regarding SMD and baseline clinical factors. The median follow-up was 20.3 months. Patients with low SMI had a significantly shorter PFS (HR = 1.66 [95% CI: 1.05–2.61]; p = 0.0291) at univariate analysis, but not at the multivariate analysis. They also had a significantly shorter OS (HR = 2.19 [95% CI: 1.31–3.64]; p = 0.0026). The multivariate analysis confirmed baseline SMI as an independent predictor for OS (HR = 2.19 [1.31–3.67]; p = 0.0027). We did not find significant relationships between baseline SMD and clinical outcomes, nor between ORR, irAEs and baseline SMI (data not shown). Low SMI is associated with shortened survival in advanced cancer patients treated with PD1/PDL1 checkpoint inhibitors. However, the lack of an association between SMI and clinical response suggests that sarcopenia may be generally prognostic in this setting rather than specifically predictive of response to immunotherapy.