PD-L1 Checkpoint Inhibitors Research Articles

Combination of T-Cell Bispecific Antibodies With PD-L1 Checkpoint Inhibition Elicits Superior Anti-Tumor Activity.

T-cell Bispecific Antibodies (TCBs) elicit anti-tumor responses by cross-linking T-cells to tumor cells and mediate polyclonal T-cell expansion that is independent of T-cell receptor specificity. TCBs thus offer great promise for patients who lack antigen-specific T-cells or have non-inflamed tumors, which are parameters known to limit the response of checkpoint inhibitors. The current study deepens the understanding of TCB mode of action and elaborates on one of the adaptive resistance mechanisms following its treatment in vivo in humanized mice and syngeneic pre-clinical tumor models. Single-agent TCB treatment reduced tumor growth compared with controls and led to a 2–10-fold increase in tumor-infiltrating T-cells, regardless of the baseline tumor immune cell infiltration. TCB treatment strongly induced the secretion of CXCL10 and increased the frequency of intra-tumor CXCR3+ T-cells pointing to the potential role of the CXCL10-CXCR3 pathway as one of the mechanisms for T-cell recruitment to tumors upon TCB treatment. Tumor-infiltrating T-cells displayed a highly activated and proliferating phenotype, resulting in the generation of a highly inflamed tumor microenvironment. A molecular signature of TCB treatment was determined (CD8, PD-1, MIP-a, CXCL10, CXCL13) to identify parameters that most robustly characterize TCB activity. Parallel to T-cell activation, TCB treatment also led to a clear upregulation of PD-1 on T-cells and PD-L1 on tumor cells and T-cells. Combining TCB treatment with anti-PD-L1 blocking antibody improved anti-tumor efficacy compared to either agent given as monotherapy, increasing the frequency of intra-tumoral T-cells. Together, the data of the current study expand our knowledge of the molecular and cellular features associated with TCB activity and provide evidence that the PD-1/PD-L1 axis is one of the adaptive resistance mechanisms associated with TCB activity. This mechanism can be managed by the combination of TCB with anti-PD-L1 blocking antibody translating into more efficacious anti-tumor activity and prolonged control of the tumor outgrowth. The elucidation of additional resistance mechanisms beyond the PD-1/PD-L1 axis will constitute an important milestone for our understanding of factors determining tumor escape and deepening of TCB anti-tumor responses in both solid tumors and hematological disorders.

15156 Autoimmune cutaneous disorders associated with PD-1 and PD-L1 inhibitors: Pharmacovigilance analysis of the FDA Adverse Event Reporting System from the Research on Adverse Drug Events and Reports program

Background: Autoimmune cutaneous disorders (AICD have been inconsistently reported during treatment with PD-1 (nivolumab, pembrolizumab, cemiplimab) and PD-L1 (atezolizumab, avelumab, durvalumab) checkpoint inhibitors. Case reports exist in the literature for 2 AICDs, vitiligo (VI) and lichen planus (LP), but an association with a PD1/PDL1 agents has not been well substantiated. The aim of this study was to determine if an association exists for these AICDs and PD-1 and PD-L1 inhibitors within a large database, the FDA Adverse Event Reporting System (FAERS).

A Phase I Dose Escalation Study of PT-112 in Patients with Relapsed or Refractory Multiple Myeloma

Background: PT-112 is a novel pyrophosphate-platinum conjugate with a multi-modal mechanism of action that induces immunogenic cell death and is not susceptible to DNA-repair drug resistance pathways. In phase I studies in solid tumors, PT-112 demonstrated safety and efficacy as single agent and in combination with PD-L1 checkpoint inhibitor avelumab, crossing a range of dose levels (DL) and tumor types, including in heavily pre-treated patients (pts) non-responsive to immunotherapy and refractory to other modalities. Non-clinical, in vivo research using advanced imaging technology demonstrated that PT-112 reached the highest concentrations in bone tissue (osteotropism). Moreover, PT-112 was highly active in the orthotopic, immune-competent Vk*MYC mouse model of multiple myeloma, including drug-resistant transplant variants. Thus, a rationale for PT-112 as an investigational candidate in multiple myeloma was established. Here, we present results of a phase I dose escalation study of PT-112 in pts with relapsed or refractory multiple myeloma (RRMM). Methods: A 3+3 design was used to determine the recommended phase 2 dose (RP2D) for PT-112 (28-day cycle IV days 1, 8, 15) in pts with evaluable RRMM who had exhausted available therapies (Tx), with adequate bone marrow (abs neutrophil count ≥ 1.0 x 109/L; platelet count ≥ 50 x 109/L; and hemoglobin ≥ 8.0 g/dL) and renal function (calculated creatinine clearance ≥ 30 mL/min), and ECOG PS 0-2. Results: A total of 24 pts were treated with PT-112 monotherapy across 6 DLs: 125 mg/m2, 3 pts; 180 mg/m2, 4 pts; 250 mg/m2, 5 pts; 300 mg/m2, 4 pts; 360 mg/m2, 4 pts; 420 mg/m2, 4 pts. Patients had a median age of 72 years and were heavily pre-treated, with a median of 8 prior lines of systemic Tx: 22 (92%) pts were triple-class refractory with 19 (79%) pts penta-refractory, and 3 (13%) pts refractory to BCMA-based therapies. The most common treatment-related adverse events (TRAEs) were thrombocytopenia (58%), neutropenia (42%), diarrhea (38%), and nausea (38%). 38% of pts had ≥1 grade 3 non-hematologic TRAE, with no grade 4 non-hematologic TRAEs reported. One dose-limiting toxicity (DLT) of grade 4 neutropenia occurred at the 420 mg/m2 DL. In addition, due to frequent dose reductions and modifications at this DL, the safety committee declared 360 mg/m2 as the RP2D. Among 8 patients who received a starting dose at / above the RP2D, 2 had stable disease and 4 experienced responses to PT-112 Tx. These included a confirmed partial response (PR) achieved in a 79-year-old pt with kappa free light chain (FLC) disease treated at 360 mg/m2, whose previous Tx included combination regimens with most approved therapies (penta-refractory) and stem cell transplantation. FLC levels declined by 65% from baseline on PT-112 therapy and the pt remained progression free for 4.5 months. A 72-year-old pt treated at the 420 mg/m2 DL, reduced to 250mg/m2 every other week over the course of Tx due to grade 3-4 cytopenias, had a confirmed minor response. Prior Tx with multiple lines given over 9 years included stem cell transplantation, most approved therapies (penta-refractory), prior investigational antibody and CAR-T cell Tx (primary refractory to CAR-T). The patient was M-protein negative, kappa FLC levels declined by 32% following the first dose reduction, and the pt remained progression free and clinically stable without complaints for 4.5 months. Additionally, two transient, unconfirmed PRs occurred in patients at the 420mg/m2 DL: in a triple-class-refractory 82-year-old previously treated with 5 lines of Tx, with 70% reduction in kappa FLC during cycle 1; and in a penta-refractory 85-year-old, who experienced disappearance of M-protein during cycle 1 and Gr 4 neutropenia (DLT). Conclusions: PT-112 monotherapy was feasible and well tolerated in this heavily pre-treated, multi-refractory multiple myeloma population, and the Phase I clinical data appear to validate the developmental hypothesis, built upon activity in the Vk*MYC mouse model of multiple myeloma. Responses were confirmed in 25% of patients treated at / above the RP2D using single-agent PT-112, an encouraging result in a dose escalation trial conducted in heavily refractory patients. Activity of PT-112 in RRMM patients may be explained by its osteotropism and its unique mechanism of action compared to other drug classes used to treat this disease. Further clinical study of PT-112 in RRMM is warranted in a phase 2 clinical trial. Disclosures Ailawadhi: Celgene: Honoraria; Janssen: Research Funding; Pharmacyclics: Research Funding; Amgen: Research Funding; Medimmune: Research Funding; BMS: Research Funding; Cellectar: Research Funding; Phosplatin: Research Funding; Takeda: Honoraria. Vogl:Janssen: Consultancy; Celgene: Consultancy; MorphoSys: Consultancy; Takeda: Consultancy; Active Biotech: Consultancy, Research Funding; Oncopeptides: Consultancy; Karyopharm: Consultancy. Ames:Phosplatin Therapeutics: Current Employment, Current equity holder in private company. Yim:Phosplatin Therapeutics: Current Employment, Current equity holder in private company. Price:Phosplatin Therapeutics: Current Employment, Current equity holder in private company. Jimeno:Phosplatin Therapeutics: Current Employment, Current equity holder in private company.

Integrated analysis of concomitant medications and oncological outcomes from PD-1/PD-L1 checkpoint inhibitors in clinical practice.

BackgroundConcomitant medications, such as steroids, proton pump inhibitors (PPI) and antibiotics, might affect clinical outcomes with immune checkpoint inhibitors.MethodsWe conducted a multicenter observational retrospective study aimed at evaluating the impact of concomitant medications on clinical outcomes, by weighing their associations with baseline clinical characteristics (including performance status, burden of disease and body mass index) and the underlying causes for their prescription. This analysis included consecutive stage IV patients with cancer, who underwent treatment with single agent antiprogrammed death-1/programmed death ligand-1 (PD-1/PD-L1) with standard doses and schedules at the medical oncology departments of 20 Italian institutions. Each medication taken at the immunotherapy initiation was screened and collected into key categories as follows: corticosteroids, antibiotics, gastric acid suppressants (including proton pump inhibitors - PPIs), statins and other lipid-lowering agents, aspirin, anticoagulants, non-steroidal anti-inflammatory drugs (NSAIDs), ACE inhibitors/Angiotensin II receptor blockers, calcium antagonists, β-blockers, metformin and other oral antidiabetics, opioids.ResultsFrom June 2014 to March 2020, 1012 patients were included in the analysis. Primary tumors were: non-small cell lung cancer (52.2%), melanoma (26%), renal cell carcinoma (18.3%) and others (3.6%). Baseline statins (HR 1.60 (95% CI 1.14 to 2.25), p=0.0064), aspirin (HR 1.47 (95% CI 1.04 to 2.08, p=0.0267) and β-blockers (HR 1.76 (95% CI 1.16 to 2.69), p=0.0080) were confirmed to be independently related to an increased objective response rate. Patients receiving cancer-related steroids (HR 1.72 (95% CI 1.43 to 2.07), p<0.0001), prophylactic systemic antibiotics (HR 1.85 (95% CI 1.23 to 2.78), p=0.0030), prophylactic gastric acid suppressants (HR 1.29 (95% CI 1.09 to 1.53), p=0.0021), PPIs (HR 1.26 (95% CI 1.07 to 1.48), p=0.0050), anticoagulants (HR 1.43 (95% CI: 1.16 to 1.77), p=0.0007) and opioids (HR 1.71 (95% CI 1.28 to 2.28), p=0.0002) were confirmed to have a significantly higher risk of disease progression. Patients receiving cancer-related steroids (HR 2.16 (95% CI 1.76 to 2.65), p<0.0001), prophylactic systemic antibiotics (HR 1.93 (95% CI 1.25 to 2.98), p=0.0030), prophylactic gastric acid suppressants (HR 1.29 (95% CI 1.06 to 1.57), p=0.0091), PPI (HR 1.26 (95% CI 1.04 to 1.52), p=0.0172), anticoagulants (HR 1.45 (95% CI 1.14 to 1.84), p=0.0024) and opioids (HR 1.53 (95% CI 1.11 to 2.11), p=0.0098) were confirmed to have a significantly higher risk of death.ConclusionWe confirmed the association between baseline steroids administered for cancer-related indication, systemic antibiotics, PPIs and worse clinical outcomes with PD-1/PD-L1 checkpoint inhibitors, which can be assumed to have immune-modulating detrimental effects.

Targeting Glutamine Metabolism and PD-L1: A Novel Anti-tumor Pas de Deux

In this issue of Molecular Cell, Byun etal. (2020) find that the dual targeting of glutamine metabolism and the PD-L1 checkpoint inhibitor augments anti-tumor immunity. Mechanistically, decreased glutamine availability attenuated S-glutathionylation of SERCA, resulting in an increase in cytosolic calcium, enhanced NF-κB activity, and upregulation of programmed death-ligand 1.

Id1 and PD-1 Combined Blockade Impairs Tumor Growth and Survival of KRAS-mutant Lung Cancer by Stimulating PD-L1 Expression and Tumor Infiltrating CD8+ T Cells.

Simple SummaryLung adenocarcinoma is the most frequent lung cancer subtype. Many of those adenocarcinomas of the lung are driven by the KRAS gene. Although immunotherapy has significantly improved the clinical outcomes of patients with lung adenocarcinomas, many patients do not benefit from that therapeutic strategy. Id1 is a protein involved in immunosuppression. Here we aimed to test whether a combined blockade of Id1 and PD-1 is able to improve outcomes of mice models with KRAS-driven lung adenocarcinoma.The use of PD-1/PD-L1 checkpoint inhibitors in advanced NSCLC is associated with longer survival. However, many patients do not benefit from PD-1/PD-L1 blockade, largely because of immunosuppression. New immunotherapy-based combinations are under investigation in an attempt to improve outcomes. Id1 (inhibitor of differentiation 1) is involved in immunosuppression. In this study, we explored the potential synergistic effect of the combination of Id1 inhibition and pharmacological PD-L1 blockade in three different syngeneic murine KRAS-mutant lung adenocarcinoma models. TCGA analysis demonstrated a negative and statistically significant correlation between PD-L1 and Id1 expression levels. This observation was confirmed in vitro in human and murine KRAS-driven lung cancer cell lines. In vivo experiments in KRAS-mutant syngeneic and metastatic murine lung adenocarcinoma models showed that the combined blockade targeting Id1 and PD-1 was more effective than each treatment alone in terms of tumor growth impairment and overall survival improvement. Mechanistically, multiplex quantification of CD3+/CD4+/CD8+ T cells and flow cytometry analysis showed that combined therapy favors tumor infiltration by CD8+ T cells, whilst in vivo CD8+ T cell depletion led to tumor growth restoration. Co-culture assays using CD8+ cells and tumor cells showed that T cells present a higher antitumor effect when tumor cells lack Id1 expression. These findings highlight that Id1 blockade may contribute to a significant immune enhancement of antitumor efficacy of PD-1 inhibitors by increasing PD-L1 expression and harnessing tumor infiltration of CD8+ T lymphocytes.

Neuro-Ophthalmic Complications in Patients Treated With CTLA-4 and PD-1/PD-L1 Checkpoint Blockade.

In recent years, CTLA-4 and PD-1/PD-L1 checkpoint inhibitors have proven to be effective and have become increasingly popular treatment options for metastatic melanoma and other cancers. These agents work by enhancing autologous antitumor immune responses. Immune-related ophthalmologic complications have been reported in association with checkpoint inhibitor use but remain incompletely characterized. This study seeks to investigate and further characterize the neuro-ophthalmic and ocular complications of immune checkpoint blockade treatment. A survey was distributed through the secure electronic data collection tool REDCap to neuro-ophthalmology specialists in the North American Neuro-Ophthalmology Society listserv. The study received human subjects approval through the University of California at Los Angeles Institutional Review Board. The survey identified patients sent for neuro-ophthalmic consultation while receiving one or more of a PD-1 inhibitor (pembrolizumab, nivolumab, or cemiplimab); PD-L1 inhibitor (atezolizumab, avelumab, or durvalumab); or the CTLA-4 inhibitor ipilimumab. Thirty-one patients from 14 institutions were identified. Patient demographics, neuro-ophthalmic diagnosis, diagnostic testing, severity, treatment, clinical response, checkpoint inhibitor drug used, and cancer diagnosis was obtained. The checkpoint inhibitors used in these patients included pembrolizumab (12/31), nivolumab (6/31), combined ipilimumab with nivolumab (7/31, one of whom also received pembrolizumab during their course of treatment), durvalumab (3/31), ipilimumab (2/31), and cemiplimab (1/31). Malignant melanoma (16/31) or nonsmall cell lung carcinoma (6/31) were the most common malignancies. The median time between first drug administration and the time of ophthalmological symptom onset was 14.5 weeks. Eleven patients had involvement of the optic nerve, 7 patients had inflammatory orbital or extraocular muscle involvement, 6 patients had ocular involvement from neuromuscular junction dysfunction, 4 patients had cranial nerve palsy, and 4 patients had non neuro-ophthalmic complications. Use of systemic corticosteroids with or without stopping the checkpoint inhibitor resulted in improvement of most patients with optic neuropathy, and variable improvement for the other ophthalmic conditions. This study describes the variable neuro-ophthalmic adverse events associated with use of immune checkpoint inhibitors and contributes a more thorough understanding of their clinical presentations and treatment outcomes. We expect this will increase awareness of these drug complications and guide specialists in the care of these patients.

Programmed Death Receptor Ligand One Expression May Independently Predict Survival In Non-Small Cell Lung Carcinoma Brain Metastases Patients Receiving Immunotherapy

Programmed 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. In 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). Forty-eight BM patients with available PD-L1 expression were identified. PDL1 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). In patients with NSCLC-BMs treated with PD-1/PD-L1 checkpoint inhibitors and local treatment, PD-L1 expression may predict OS independent of lungGPA. 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.

Abstract B17: Activating mutations of phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) gene confer sensitivity to PD-L1 checkpoint inhibition in metastatic adenocarcinoma patients

Abstract Background: Immunotherapy has produced durable responses in advanced cancers with microsatellite instability (MSI). However, response rates remain low in many adenocarcinomas, and biomarkers predictive of response are urgently needed. Preliminary data suggest that PD-L1 checkpoint expression is increased in early-stage microsatellite stable colorectal cancers with PIK3CA mutations as compared to wild-type PIK3CA. Increased expression of PD-L1 has been reported to be associated with response to immunotherapy. The impact of activating PIK3CA mutations on response to anti-PD-L1 checkpoint inhibitors in metastatic adenocarcinomas remains unknown. The objective of our study is to evaluate the impact of activating PIK3CA mutations on treatment outcomes with anti-PD-L1 checkpoint inhibitors in metastatic adenocarcinomas without MSI. Methods: We retrospectively identified patients with metastatic adenocarcinoma treated with anti-PD-L1 antibody, either as monotherapy or in combination with anti-PD-1 antibody, in early-phase clinical trials at the MD Anderson Clinical Center for Targeted Therapy. Molecular profiling was performed on archived primary or metastatic tumor tissue using CLIA-certified targeted next-generation sequencing (FoundationOne or Oncomine), and results were annotated for functional significance by the MD Anderson Precision Oncology Decision Support Team. Fischer's exact test was used for group comparisons. Median time to treatment failure (TTF) was estimated using the Kaplan and Meier method, and compared among groups by the log-rank test. Results: A total of 27 patients (female, 20; male, 7) with metastatic adenocarcinomas without MSI from 12 different sites (breast, colon and esophageal cancers being the most common cancer types with 7, 5 and 2 patients, respectively) were treated with anti-PD-L1 antibody. Activating PIK3CA mutations were present in 6 (22%) patients (E545K, 2; H1047R, 2; E542K, 1; co-occurring R88Q and K111N, 1). Patients with PIK3CA mutations had longer median TTF than patients with a wild-type PIK3CA (8.7 vs. 2.8 months, P=0.045). In addition, 3 of 6 (50%) patients with PIK3CA mutations had stable disease on treatment for &amp;gt; 6 months as compared to 1 of 21 (4.8%) patients with a wild-type PIK3CA (P=0.02). Conclusion: Our preliminary data suggest that activating PIK3CA mutations in patients with metastatic adenocarcinoma without MSI are associated with prolonged stable disease and longer TTF on treatment with PD-L1 checkpoint inhibitors. Future studies to validate our observations are warranted. Citation Format: Maliha Nusrat, David Hong, Sarina A. Piha-Paul, Vivek Subbiah, Jordi Rodon, Apostolia Tsimberidou, Abha Adat, Yan Wang, Michael Overman, Scott Kopetz, Funda Meric-Bernstam, Filip Janku. Activating mutations of phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) gene confer sensitivity to PD-L1 checkpoint inhibition in metastatic adenocarcinoma patients [abstract]. In: Proceedings of the AACR Special Conference on Targeting PI3K/mTOR Signaling; 2018 Nov 30-Dec 8; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(10_Suppl):Abstract nr B17.

Autoimmunity linked protein phosphatase PTPN22 as a target for cancer immunotherapy

BackgroundCancer immunotherapy has evolved from interferon-alpha (IFNα) and interleukin-2 in the 1980s to CTLA-4 and PD-1/PD-L1 checkpoint inhibitors (CPIs), the latter highlighting the importance of enhancing T-cell functions. While the...

Comment on: Jilkova, Z.M.; et al. "Predictive Factors for Response to PD-1/PD-L1 Checkpoint Inhibition in the Field of Hepatocellular Carcinoma: Current Status and Challenges" Cancers 2019, 11, 1554.

I read with interest the article 'Predictive Factors for Response to PD-1/PD-L1 Checkpoint Inhibition in the Field of Hepatocellular Carcinoma: Current Status and Challenges' [...].

Reply to Comment on "Jilkova, Z.M.; et al. Predictive Factors for Response to PD-1/PD-L1 Checkpoint Inhibition in the Field of Hepatocellular Carcinoma: Current Status and Challenges" Cancers 2019, 11, 1554.

We appreciate the comments made on our review paper focused on possible predictive factors for responses to PD-1/PD-L1 checkpoint inhibitors in the field of hepatocellular carcinoma [...].

495P Lack of liver metastases identifies a group of MSS metastatic colorectal cancer with potential benefit from PD-1/PD-L1 targeting

Microsatellite stable (MSS) metastatic colorectal cancer (mCRC) represent 95% of all mCRC cases and are characterized by resistance to PD-1 or PD-L1 checkpoint inhibition. Liver metastatic disease has been associated with decreased responses to immunotherapy in non-small cell lung cancer and melanoma. However, the impact of metastatic disease to the liver in MSS mCRC on treatment response has not been investigated in the setting of PD-1 or PD-L1 targeting.

Abstract 5607: Broad acting glutamine antagonism remodels the tumor microenvironment, induces distinctive immune modulation, and synergizes with immune checkpoint blockade

Abstract We previously reported that DRP-104, a novel broad acting glutamine antagonist, has significant therapeutic potential in cancer via directly targeting tumor metabolism and inducing a potent antitumor immune response. Here we sought to further elucidate the immunomodulatory effect of DRP-104 on tumor growth inhibition as a single agent and in combination with PD-1/PD-L1 checkpoint inhibitors in the MC38 and CT26 colon cancer syngeneic models. We utilized multiple technologies to assess mechanistic effects on immune cells in vivoincluding flowcytometry, multiplex immunoassay, gene expression profiling and GeoMx™ digital spatial profiling. DRP-104 mediated tumor growth inhibition was associated with increased tumor-infiltrating leukocytes (TIL) including T, NKT, and NK cells, M1-polarized tumor associated macrophages, and decreased immune-suppressive cells such as MDSCs. Nanostring® IO360 analysis revealed broad immunological modulation such as increase in cytotoxicity/antigen presentation score, increase in tumor metabolic stress/apoptotic score and decrease in cell proliferation score. GeoMx™ profiling also showed increased tumoral T cells and granzyme B expression. Luminex analysis of tumor lysates revealed DRP-104 treatment decreased pro-tumorigenic proteins, such as VEGF and IL-8. DRP-104 showed significant dose dependent tumor growth inhibition and regressions as a single agent in mouse syngeneic tumor models, including those resistant to immune checkpoint inhibitors. Lastly, combination of DRP-104 with anti-PD-1 Ab or anti-PD-L1 Ab further reduced tumor growth resulting in significant improvement in survival with long-term durable cures. In summary, DRP-104 treatment resulted in broad remodeling of the tumor microenvironment including enhanced infiltration and function of multiple immune cells distinct from activities obtained by a checkpoint inhibitor treatment. Combination therapy of DRP-104 with anti-PD-1/PD-L1 achieved significantly enhanced anti-tumor efficacy including long-term durable cures even in checkpoint inhibitor resistant models. This unique and non-overlapping mechanism of action supports clinical development of DRP-104 alone and in combination with PD-1/PD-L-1 checkpoint inhibitors. Citation Format: Yumi Yokoyama, Robert Wild. Broad acting glutamine antagonism remodels the tumor microenvironment, induces distinctive immune modulation, and synergizes with immune checkpoint blockade [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 5607.

Abstract 3172: Evaluation of cytotoxic T cell infiltration and clinical benefit from PD-L1 checkpoint inhibition among PIK3CA mutant microsatellite stable (MSS) metastatic adenocarcinoma patients

Abstract Background: Immunotherapy has produced durable responses in advanced cancers with microsatellite instability. However, response rates remain very low for microsatellite stable (MSS) adenocarcinomas, and biomarkers predictive of response are urgently needed. PI3K pathway alterations are known to modulate anti-tumor immune microenvironment. We previously reported increased cytotoxic T cell infiltration and greater clinical benefit from immunotherapy among PIK3CA mutant MSS colorectal cancer patients as compared to PIK3CA wild-type patients. Here, we investigated the immune repertoire and treatment outcomes with anti-PD-L1 checkpoint inhibitors in PIK3CA mutant MSS metastatic adenocarcinoma patients. Methods: We retrospectively identified metastatic adenocarcinoma patients treated with anti-PD-L1 antibody either as monotherapy or in combination with anti-PD-1 antibody in early phase clinical trials at the MD Anderson Center for Targeted Therapy. Molecular profiling was performed on archived primary or metastatic tumor tissue using CLIA certified targeted next generation sequencing (FoundationOne or Oncomine). PIK3CA mutations were annotated for functional significance by the Precision Oncology Decision Support Team. Density of cytotoxic T cells was determined using immunohistochemistry (IHC) on biopsy or resection specimens. Microsatellite status was assessed using IHC or polymerase chain reaction. Median time to treatment failure (TTF) was estimated using Kaplan and Meier method. Groups were compared using Fischer's exact, Student's T test or Log-rank test, as appropriate. Results: Twenty-seven patients with MSS metastatic adenocarcinoma (female, 20; male, 7) from 12 different sites were treated with anti-PD-L1 antibody. Breast, colon and esophageal cancers were the most common cancers with 7, 5 and 3 patients, respectively. Activating PIK3CA mutations were present in 7/27 (26%) patients (H1047R, 3; E545K, 2; E542K, 1; co-occuring R88Q and K111N, 1). Patients with activating PIK3CA mutations had trend towards longer median TTF as compared to PIK3CA wild-type patients (6.6 vs. 3.1 months, P=0.1). Similarly, 3/7 (42.9%) patients with activating PIK3CA mutations had stable disease (SD) &amp;gt; 6 months as compared to 2/20 (10%) patients with wild type PIK3CA (P=0.09). CD8 densities were available for 8 patients (5 PIK3CA mutant, 3 PIK3CA wild). Among PIK3CA mutant patients, mean CD8 density was higher in patients who had SD &amp;gt; 6 months as compared to those who did not (630.3 vs 305.1 cells/mm3; P=0.06). Conclusion: Activating PIK3CA mutations are enriched among MSS metastatic adenocarcinoma patients with prolonged SD (&amp;gt; 6 months) on anti-PD-L1 treatment. PIK3CA mutant patients with prolonged SD have higher CD8 densities, possibly due to high-affinity neopeptide-HLA interactions. Larger studies to validate our observations are warranted, including assessment of neopeptide load and HLA types, which may help identify an immunotherapy sensitive subset of PIK3CA mutant MSS adenocarcinoma. Citation Format: Maliha Nusrat, Coya Tapia, S. Greg Call, David S. Hong, Sarina A. Piha-Paul, Vivek Subbiah, Jordi Rodon, Apostolia M. Tsimberidou, Abha Adat, Yan Wang, Funda Meric-Bernstam, Michael J. Overman, Scott Kopetz, Filip Janku. Evaluation of cytotoxic T cell infiltration and clinical benefit from PD-L1 checkpoint inhibition among PIK3CA mutant microsatellite stable (MSS) metastatic adenocarcinoma patients [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 3172.

Abstract 3267: Identification of a novel biomarker response in a prospective clinical trial of immune checkpoint blockade in recurrent ovarian carcinoma

Abstract The role of immune checkpoint inhibitors (ICPIs) in ovarian cancer continues to be refined. The presence of intratumoral T cells in ovarian tumors correlates with improved survival and progression, suggesting that immune modulation, such as by ICPIs, may be beneficial. However, a better understanding of the immune effects following ICPI use, particularly in those with a long progression free survival, is needed. Thus, we used imaging mass cytometry (IMC) to compare the tumor immune landscape of patients with ovarian cancer before and after a CTLA4 immune checkpoint inhibitor treatment to determine the association between alterations in immune landscapes and progression free survival. Fine needle biopsies were obtained from 8 patients with recurrent platinum-resistant ovarian carcinoma enrolled in a phase 2 randomized trial evaluating the efficacy of Tremelimumab and Durvalumab (CTLA4 and PDL1 checkpoint inhibitors, respectively) in recurrent ovarian cancer treatment. Each patient had a pre-treatment biopsy and on-treatment biopsy after 3 cycles of CTLA4 inhibitor therapy. Progression free time (PFS) was recorded with 3 patients with a long PFS (&amp;gt;180 days) and 5 with short PFS (&amp;lt;60 days). Formalin fixed paraffin embedded (FFPE) tissue sections were stained for IMC analysis via Fluidigm protocol with 34 metal-tagged antibodies to detect various cell and immune related markers. The IMC data was obtained using the Fluidigm Helios CyTOF instrument and Hyperion Imaging System laser ablation module. A novel image informatics pipeline through Matlab was used to assess the image intensity of each marker and cell location. Using the developed image informatics pipeline, cell types and locations were analyzed for 16 samples from 8 patients. In all patients, mean CD8+ T cell densities had an increased trend in on-treatment vs pre-treatment samples (205.6 v 129.9 cells/mm2, p=0.086). An analysis of cell location found that in all patients on-treatment, the mean number of CD8+ T cells adjacent to M2 macrophages increased significantly (0.09 v. 0.17 cells, p = 0.0460) as well as the mean number of CD8+ T cells adjacent to B7H4+ tumor cells (0.035 v. 0.01 cells, p = 0.046). Furthermore, patients with a long PFS had a significantly higher number of CD8+ cells neighboring B cells on-treatment than short PFS (0.12 v. 0.27 cells, p=0.028). Using IMC and novel image informatics pipeline, we found that patients with recurrent ovarian cancer treated with Tremelimumab with a long PFS mounted a significant immune response compared to patients with a short PFS, with a higher number of CD8+ T cells neighboring B cells after treatment. For all patients, the immune landscape altered after treatment. To our knowledge, this is the first known use of IMC to demonstrate immune response in ovarian cancer following ICPI therapy. Overall, IMC and image informatics pipeline are robust tools that simultaneously analyze multiple biomarkers and spatial location of cells to better assess the tumor immune microenvironment and cellular interactions. Citation Format: Han Cun, Emily M. Hinchcliff, Ying Zhu, Sammy Ferri-Borgogno, Rita Cheng, Jared K. Burks, Stephen T. Wong, Amir A. Jazaeri, Samuel C. Mok. Identification of a novel biomarker response in a prospective clinical trial of immune checkpoint blockade in recurrent ovarian 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 3267.

Abstract 3170: Different genomic mutations signatures are associated to specific PD-L1/TMB states on lung cancer with potential value for patients screening for immunotherapy

Abstract Objective: PD-L1 expression and Tumor Mutation Burden (TMB) have independently emerged as prospective biomarkers of response to anti PD1-/PDL1 checkpoint inhibitors. However, TMB has not fully proven its value as a biomarker of Immunotherapy response in lung cancer. Moreover, FDA-approved CDx PD-L1 expression alone is not an optimal biomarker for checkpoint inhibitors and combined use of MSI, TMB and PD-L1 protein levels has been proposed. Here we present the correlation between genomic landscape, including TMB and MSI with PDL1 IHC in lung cancer specimens to help identify immunogenomic profiles for stratification of patients for check-point inhibitors therapies evaluation. Methods: 874 FFPE clinical samples across cancer types were characterized in our CLIA/CAP accredited clinical laboratory using a CLIA-validated NGS-based assay that interrogates SNVs, indels, TMB and Microsatellite Status (27 MS markers) using a 323 gene panel. TMB (mutations/Mb) is categorized as low (≤7), intermediate (7&amp;lt;TMB≤15) and high: (greater than 15). The de-identified aggregated results paired with PD-L1 IHC data from 424 lung cancer samples were analyzed and correlations between PD-L1 tumor proportion scores (TPS) and TMB results were made. In silico analyses were also performed on 5939 lung cancer samples from public databases. Results: The detected TMB median in lung cancer was 8.6 (range 0-126.4). Median PD-L1 TPS was 7%, with 26% of samples being PD-L1 negative (TPS&amp;lt;1%), 44% Low expressing (≥1-49%) and 31% High (≥50%). All samples were MSS. We found poor correlation between PD-L1 expression and TMB in NSCLC (r2=0.266). We classified samples based on TMB and PD-L1 TPS and found mutational correlations specific to in each of the following groups: PD-L1 High/TMB Low, PD-L1 High/TMB High, PD-L1 Low/TMB High, PD-L1 High/TMB High, and PD-L1 Neg/TMB High. Of note 67% (34/51) of PD-L1 High/TMB Low samples presented mutations either on EGFR (12%), KRAS (23.5%) or in genes from known driver TRK/MAPK pathways, whereas only KRAS was part of the frequently mutated gene signature with 36.5% (13/36) samples mutated on PD-L1 High/TMB High samples. Neither EGFR nor KRAS were found frequently mutated on PD-L1 Low/TMB High group (n=46). Strikingly the top 12 most frequently mutated genes on PD-L1 Neg/TMB High tumors were TP53, LRP1B, SPTA1, SMARCA4, GNAS, ALK, FGFR2, SLIT2, ROS1, AMER1, FAT1, and MED12. We found statistically significant co-occurrences between LRP1B and 7 other genes from this signature in additional 5939 lung cancer patients assessed. Conclusions: TMB and PD-L1 results do not correlate in lung cancer specimens. Common genomic alteration signatures might define subsets of lung cancer tumors with no PD-L1 expression to complement TMB and PD-L1 on the selection criteria for patients whom may benefit from checkpoint inhibitors. Citation Format: Fernando J. Lopez-Diaz, Lauryn Keeler, Forrest Blocker, Shiloh Sprankles, Ryan Bender, Sally Agersborg, Lawrence Weiss, Vincent Funari. Different genomic mutations signatures are associated to specific PD-L1/TMB states on lung cancer with potential value for patients screening for immunotherapy [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 3170.

Abstract 5903: Clinical immune and genomic profiling of STK11 mutant non-squamous non-small cell lung cancer

Abstract Background: The use of immune PD-1/PD-L1 checkpoint inhibitors (ICI) has dramatically altered the treatment of advanced Non-Small Cell Lung Cancer (NSCLC). However, a large proportion of patients with NSCLC do not derive clinical benefit from ICI treatment. Recent studies have identified STK11 mutations leading to loss of LKB1 in NSCLC as drivers of primary resistance to ICI treatment. Using a clinical cohort of patients whose tumors underwent comprehensive genomic and immune transcriptomic analysis, we characterized the immune gene expression profile of STK11 mutant non-squamous NSCLC tumors and identified TRIM29 as a potential therapeutic target in STK11 mutant non-squamous NSCLC. Methods: We performed comprehensive analysis of the genomic and immunological landscape of 199 formalin-fixed, paraffin-embedded tumor samples (obtained prior to ICI treatment) from advanced stage non-squamous NSCLC patients treated at Roswell Park Comprehensive Cancer Center using a CLIA-certified laboratory test that included targeted NGS genomic sequencing, gene fusion analysis, and RNA-seq of 394 immune transcripts. Differential gene expression analysis was performed using R/Bioconductor package limma with Benjamini-Hochberg adjusted p-values reported. This study was approved by Roswell Park internal review board review (protocol BDR 091817) according to institutional policy for nonhuman subjects research. Results: Among the cohort of 199 cases, 32 contained truncating STK11 mutations. STK11 mutant cases showed an immunosuppressive environment with decreased PD-L1 expression (p=0.01) and decreased T-cell inflammation gene expression signature (p=0.0029) consistent with prior published cohorts. Analysis of differentially expressed immune genes signatures showed significant decreases in antigen presentation (p=0.015) and processing (p=0.044), NK cell activation (p=0.039), chemokine and cytokine signaling (p=0.044), immune checkpoint pathways (p=0.015), innate immune response (p=0.04), and interferon signaling (p=0.039). The top upregulated gene in STK11 mutant cases was TRIM29 (p=0.03). Other overexpressed targets included ID3 (p=0.009), KRT7 (p=0.02), and NOTCH3 (p=0.05). Interrogation of TCGA LUAD dataset also demonstrated elevated TRIM29 expression (p=0.006) in STK11-mutant compared to STK11-wild-type samples and we also confirmed elevated TRIM29 RNA and protein expression in a panel of STK11 mutant NSCLC human cell lines. Immunohistochemical staining of a cohort of 68 KRAS mutant NSLCLC patient samples also showed higher levels of TRIM29 protein staining in STK11 mutant samples. Knockdown of TRIM29 using shRNA inhibited growth of STK11 mutant tumor xenografts. TRIM29 is a E3 ubiquitin ligase and we evaluated known targets of TRIM29 and found decreased TAB2 expression in STK11 mutant NSCLC. Notably, TAB2 is also regulated by SIK1/3, which have been recently identified as signaling partners with STK11. TRIM29 has been implicated as a mediator of processes also involved in STK11 tumorigenesis such as cellular metabolism, DNA damage repair, innate immunity, and squamous differentiation. Conclusion: Using a large clinical cohort of non-squamous NSCLC patients we characterized the immunosuppressive environment of STK11 mutant tumors and identified the E3 ubiquitin ligase TRIM29 as a potential therapeutic target. Citation Format: Edwin Yau, Sarabjot Pabla, Sean Glenn, Antonios Papanicolau-Sengos, Mary Nesline, Grace Dy, Carl Morrison. Clinical immune and genomic profiling of STK11 mutant non-squamous non-small cell lung cancer [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 5903.

Abstract 4228: PLAP (placental alkaline phosphatase)-CAR-T cells specifically target colorectal cancer

Abstract Placental alkaline phosphatase, PLAP encoded by ALPP gene in humans is mainly expressed in placenta and testis, and not expressed in any other normal tissues. PLAP is overexpressed in a proportion of colorectal cancers which makes it an attractive target for CAR (chimeric antigen receptor)-T cell therapy. PLAP mRNA expression was detected in 21.4% (25 out of 117) of colorectal cancer cell lines and this expression was confirmed by FACS at the protein level. In addition, IHC staining on primary colorectal cancer tumors demonstrated PLAP expression in &amp;gt;20% of colorectal cancer tumors. We generated mouse and humanized PLAP ScFv-CAR-T cells and demonstrated high specificity against PLAP-positive colon cancer cells using RTCA (real-time cytotoxicity assay) and IFN-gamma secretion. In addition, humanized-CAR-T cells significantly decreased Lovo xenograft tumor growth in vivo. The combination of hPLAP-CAR-T cells with PD-1, PDL-1 or LAG-3 checkpoint inhibitors significantly increased the activity of hPLAP-CAR-T cells. Significance: This study demonstrates ability of novel PLAP-CAR-T cells to kill colorectal cancers and that the extent of killing can be increased by combination with checkpoint inhibitors. These preclinical results suggest that PLAP-CAR-T cells combined with checkpoint inhibitors may be developed into an effective clinical therapy for PLAP expressing colorectal and other cancers. Citation Format: Vita M. Golubovskaya, Robert Berahovich, Hua Zhou, Xianghong Liu, Feng Li, Shirley Xu, Yuehua Wei, Djamila Ouaret, Walter Bodmer, Lijun Wu. PLAP (placental alkaline phosphatase)-CAR-T cells specifically target colorectal cancer [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 4228.

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.