Utility Of Immune Checkpoint Inhibitors Research Articles

Abstract PO5-06-13: Impact of Therapy on Sites of Metastases in Triple Negative Breast Cancer

Abstract Background: Metastatic triple negative breast cancer (TNBC) is a diverse disease with the propensity to spread to visceral organs and the central nervous system (CNS). While systemic chemotherapy is commonly used, there is a growing utilization of immune checkpoint inhibitors (ICI) and antibody drug conjugates (ADC). However, few studies have examined the impact of specific therapies on individual metastatic sites, limiting clinical guidance for solitary metastases. Objective: This study aimed to evaluate the efficacy of various systemic therapies in TNBC patients with lung, liver, and CNS metastases. Methods: We analyzed data from the Dallas Metastatic Breast Cancer Study, a retrospective cohort study that includes all patients with metastatic breast cancer treated at a single academic medical center and identified 52 TNBC patients with visceral and CNS metastases diagnosed between 2009 and 2021. We correlated the site of metastasis with and treatment response, which was assessed based on imaging findings using RECIST 1.1 criteria. Results and Discussion: The median age at diagnosis of visceral metastatic disease was 52 years. Of the patients, 60% presented with de novo metastatic disease, while 40% experienced disease recurrence. The most prevalent metastatic sites were the lung (n=28), CNS (n=28), and liver (n=9). Among patients with detectable circulating tumor DNA, the most prevalent gene mutations in lung metastases were TP53 (36%), PTEN (13%), and PIK3R1 (10%). In liver metastases, TP53 (53%) and BRCA1 (15%) mutations were the most frequently observed. Similarly, in CNS metastases, TP53 (40%) and BRCA1 (13%) mutations were again most frequently detected. The notable frequency of TP53 mutations indicates the necessity for further investigations to explore potential differences in treatment approaches for patients with these mutations. The median overall survival (OS) was 14.43 months ±15.53, with the longest survival observed in patients with lung metastases (15 months), followed by liver metastases (6 months) and CNS metastases (5 months). Patients with involvement of a single visceral or CNS site had a mean OS of 15.80±18.19 months, whereas those with two sites of involvement had a mean OS of 13.08±10.18 months. Patients with metastases in all three sites had a mean OS of 8.33±8.50 months. Treatment modalities varied among patients. For liver metastases, chemotherapy (n=6), ICI (n=2), ADC (n=1), radiation therapy (n=2), and surgery (n=1) were administered. Lung metastases were treated with chemotherapy (n=26), ICI (n=4), ADC (n=5), radiation therapy (n=4), and surgery (n=1). CNS metastases were managed with chemotherapy (n=14), ICI (n=2), ADC (n=1), radiation therapy (n=21), and surgery (n=4). Systemic therapy for liver metastases resulted in stable disease (75%) and progressive disease (25%). In lung metastases, it led to stable disease (56%), partial response (23%), complete response (13%), and progressive disease (8%). CNS metastases treated with systemic therapy demonstrated stable disease (86%) and progressive disease (14%). The most commonly used systemic therapy was paclitaxel. Immunotherapy achieved a partial response (60%), stable disease (20%), and progressive disease (20%) in metastatic lesions. Treatment with ADCs resulted in stable disease (43%), partial response (29%), and progressive disease (29%). Compared to lung metastases, liver and CNS metastases exhibited lower response rates and overall survival. CNS metastases were less likely to receive systemic therapies, indicating a need for improvement. These findings highlight the importance of personalized treatment strategies tailored to individual metastatic sites in TNBC. Citation Format: Hannah Chang, Pallavi Dev, Luise Froessl, Shao-Po Huang, Christine Hodgdon, Julia Maues, Isaac Chan. Impact of Therapy on Sites of Metastases in Triple Negative Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-06-13.

A Multicenter Study on the Challenges and Real-World Utilization of Immune Checkpoint Inhibitors in Resource-Constrained Settings: Insights and Implications from India

Using immune checkpoint inhibitors (ICIs) has revolutionized cancer treatment, but access and affordability remain significant challenges, particularly in resource-constrained settings. This multicenter study evaluated the utilization, outcomes, and challenges associated with ICIs in India. Data from multiple centers involving patients treated between January 2018 and December 2021 were retrospectively collected. Patient demographics, treatment indications, biomarker testing, financial coverage, toxicity, treatment discontinuation, clinical benefit, progression-free survival (PFS), and overall survival (OS) were analyzed. Ninety-one patients were analyzed; lung cancer (39.6%) and renal cancer (11%) were the main indications for ICI use. Programmed death ligand 1 expression was tested in 40.7% and tumor mutational burden in 3.3%. Financial constraints influenced 41.8% of patients with out-of-pocket expenses. Treatment discontinuation due to financial constraints occurred in 17.6%, with 50% showing ongoing responses. The median number of cycles was 4; the median PFS was 4.6 months, and the median OS was 15.4 months. The lung cancer cohort had a median PFS of 5.7 months and a 1-year OS of 57.6%. Limited biomarker testing and 6.6% grade ¾ toxicities were observed. This study revealed challenges in ICI utilization in resource-constrained settings driven by financial constraints. Compared with prior studies, improved outcomes reflect better patient selection and evolving understanding of ICI use. However, in the absence of biosimilars, cost remains a significant barrier. Solutions to increase access include using lower doses, which may be as effective.

Identification of immune-related gene signature for non-small cell lung cancer patients with immune checkpoint inhibitors

BackgroundThe utilization of immune checkpoint inhibitors (ICIs) has become the established protocol for treating advanced non-small cell lung cancer (NSCLC). This work aimed to identify the immune-related gene signature that can predict the prognosis of NSCLC patients receiving ICI treatment. MethodsThe ImmPort database was queried to obtain a list of immune-related genes (IRGs). Differentially expressed IRGs in NSCLC patients were identified using the TCGA database. RNA-seq data and clinical information from NSCLC patients receiving immunotherapy were obtained from the GEO database (GSE93157 and ////). A gene signature was generated through multivariate Cox and LASSO regression analyses. The prognostic value and function of this gene signature were thoroughly investigated using comprehensive bioinformatics analyses. ResultsA total of 6 prognostic-related genes were identified from 617 differentially expressed genes, and two prognostic-related differentially expressed genes (CAMP and IL17A) were determined to construct gene signature. Our gene signature demonstrated superior performance compared to other clinicopathological parameters in predicting the prognosis of NSCLC patients receiving immunotherapy, with an area under the ROC curve (AUC) of 0.812. Furthermore, immune infiltration analysis indicated that the high-risk group was enriched with resting CD4 T cell memory, while the low-risk group showed a "hot" tumor microenvironment that promotes anti-tumor immunity in NSCLC patients. ConclusionGene signatures based on immune-related genes exhibited excellent indicator performance of prognosis and immune infiltration, which has the potential to be an effective biomarker for NSCLC with ICI treatment.

Enhanced tumor control activities of anti-mPD-L1 antibody and antigen-presenting cell-like natural killer cell in an allograft model

BackgroundDespite the utilization of immune checkpoint inhibitors (ICIs) in treating numerous types of cancers being approved, their efficacy in tumor control in the clinic is not satisfactory. Since adoptive cell therapy (ACT) can alter the tumor microenvironment, we hypothesized that ACT potentially synergized with ICI in tumor control and examined this hypothesis via a murine allograft model.MethodsFemale C57BL/6 mice were stimulated with interleukin 15 and granulocyte monocyte-colony stimulating factor, followed by collecting their bone marrow cells for murine NKDC cultivation. Then, female C57BL/6 mice, inoculated with lymphoma cancer cell line E.G7-OVA, were administrated with murine NKDC cells, murine anti-program cell death ligand-1 antibody (α-mPD-L1), or both for 28 days. After 28 days of treatment, mice were sacrificed whose inoculated tumors, spleen, sentinel lymph nodes, and peripheral blood were collected to measure tumor size, lymphocyte infiltration, and change of immune cell profile.ResultsCombined treatment of NKDCs with α-mPD-L1 exhibited significantly stronger tumor control efficacy than treatment of NKDCs or α-mPD-L1 alone. NKDCs/α-mPD-L1 combination increased migration of dendritic cells, CD4, CD8 T cells, and activated CD8 T cells to the tumor-bedding site, and promoted endogenous tumor-specific cytotoxic T-cell response.ConclusionThe current study confirmed our hypothesis that combining NKDC ACT with ICI therapy can potentiate tumor control efficacy by manipulating the tumor microenvironment. This study provided a novel circumstance on tumor immunotherapy.

DKK1 Impairs the Tumor Response to αPD‐1 Immunotherapy by Inactivating CD8+ T Cells and Recruiting MDSC Cells in HNSC

AbstractThe utilization of immune checkpoint inhibitors (ICIs) has received authorization for the treatment of head and neck squamous cell carcinoma (HNSC) and various other tumor types. However, a large proportion of HNSC patients exhibit unresponsiveness to ICIs. Dickkopf‐1, a secreted protein with pivotal functions in Wnt signaling pathways, is increasingly recognized for its role in modulating anti‐tumor immunity. In this study, the authors employed TCGA and GEO datasets to investigate the correlation between tumoral DKK1 expression and survival outcomes, as well as the suppressive nature of the tumor immunosuppressive microenvironment (TIME) in HNSC patients. The findings reveal a strong association between elevated DKK1 expression in HNSC tumors and poorer survival rates, along with an immunosuppressive TIME. In vivo studies utilizing subcutaneous tumor graft mouse models demonstrate that knockdown of DKK1 inhibit the growth of HNSC tumor cells in a CD8+ T cell‐dependent manner. Additionally, an inverse relationship between DKK1 expression and CD8+ T cell infiltration and activation is observed, while a positive correlation is observed with infiltration of myeloid‐derived suppressor cells (MDSCs) and CD8+ T cell exhaustion. Moreover, combining DKK1 knockdown with neutralizing antibodies against PD‐1 significantly suppress the growth of HNSC cells. Consequently, The study proposes DKK1 as a promising target for immunotherapy to enhance PD‐1 blockade therapy in HNSC. These findings show that DKK1 can thus be regarded as a potential target for immunotherapy and need further study.

Emerging Immune Checkpoint Molecules on Cancer Cells: CD24 and CD200.

Cancer immunotherapy strategies are based on the utilization of immune checkpoint inhibitors to instigate an antitumor immune response. The efficacy of immune checkpoint blockade, directed at adaptive immune checkpoints, has been demonstrated in select cancer types. However, only a limited subset of patients has exhibited definitive outcomes characterized by a sustained response after discontinuation of therapy. Recent investigations have highlighted the significance of immune checkpoint molecules that are overexpressed in cancer cells and inhibit myeloid lineage immune cells within a tumor microenvironment. These checkpoints are identified as potential targets for anticancer immune responses. Notably, the immune checkpoint molecules CD24 and CD200 have garnered attention owing to their involvement in tumor immune evasion. CD24 and CD200 are overexpressed across diverse cancer types and serve as signaling checkpoints by engaging their respective receptors, Siglec-10 and CD200 receptor, which are expressed on tumor-associated myeloid cells. In this review, we summarized and discussed the latest advancements and insights into CD24 and CD200 as emergent immune checkpoint moieties, further delving into their therapeutic potentials for cancer treatment.

Genetic Testing for Prostate Cancer, Urothelial Cancer, and Kidney Cancer

As genetic testing plays an increasingly salient role in the realm of cancer diagnosis, prognostication, and treatment, this review aims to elucidate the current landscape and future directions of genetic testing in genitourinary cancers, with a focus on prostate cancer, urothelial carcinoma, and renal cell carcinoma. With the increasing adoption of next-generation sequencing technology, the utilization and access to genetic testing in real-world settings have become critical for practicing urologists and genitourinary oncologists, especially after the approval of poly(ADP-ribose) polymerase inhibitors for prostate cancer and the utilization of immune checkpoint inhibitors. In this rapidly evolving field, this review underscores the clinical value of interpreting genetic variations and the importance of distinguishing between germline and somatic mutations, for whom testing can be prescribed, and which genes should be tested. While the current modus operandi predominantly relies on exome sequencing, we posit that the future of genetic testing in genitourinary cancers will see an expansion to encompass whole-genome sequencing, accounting for structural and regulatory variations that impact gene expression. In the upcoming era of liquid biopsies, we envisage an increase in noninvasive cancer genetic testing for the purposes of diagnosis, prognosis, treatment response, and progression monitoring, supplementing the gold-standard tissue biopsies that provide histologic information. Ultimately, thoroughly interpreting genetic testing results and the subsequent treatment implications necessitates a multidisciplinary approach. This review strives to offer urologists a comprehensive perspective on genetic testing in these prevalent urological cancers, contributing to improved diagnosis, prognosis, and treatment decision-making.

Immune checkpoint inhibitor‐related myocarditis in thymic epithelial tumors: Recent progress and perspectives

AbstractThymic epithelial tumors (TETs) are rare anterior mediastinal malignancies originating in the thymus with poor outcomes, and standard platinum‐based chemotherapy shows limited efficacy for treating metastatic or recurrent disease. In this setting, further improved novel treatment strategies are needed. Immune checkpoint inhibitors (ICIs) are widely applied in clinical practice for cancer therapy and early results of clinical trials have brought notable objective responses and lasting survival benefits to patients with TETs. However, the incidences of immune‐related adverse events (irAEs), especially cardiac adverse events, are higher than those of other tumor types. Myocarditis is a rapidly progressive and life‐threatening irAE in patients treated with ICIs, thereby hindering the further utilization of ICI in TETs patients. Therefore, this article aims to review the results of case series and clinical trials that evaluated ICIs for the treatment of TETs and to provide an overview of the clinical features of fatal ICI‐related myocarditis in TETs. Furthermore, we approach insights into the immunobiology of thymic tumors and focus on revealing the mechanisms of cardiotoxicity in patients with TETs, hoping to provide several valuable insights for maximizing the therapeutic potential of ICIs in TETs.

Spending, Utilization, and Price Trends for Immune Checkpoint Inhibitors in US Medicaid Programs: An Empirical Analysis from 2011 to 2021

Immune checkpoint inhibitors (ICIs) have become a cornerstone in cancer treatment. With high treatment costs and an increasing number of young and low-income patients with cancer, there is a need to determine the current spending and utilization of ICIs in a real-world population. The objective of this study was to outline the drug spending, utilization, and price trends of ICIs for US Medicaid programs from 2011 to 2021. A retrospective descriptive analysis was conducted using the Medicaid State Drug Utilization pharmacy summary files managed by the Centers for Medicare and Medicaid Services. Six ICIs for this study include ipilimumab, pembrolizumab, nivolumab, atezolizumab, avelumab, and cemiplimab. Yearly reimbursement and prescription numbers were calculated for six ICIs billed through Medicaid between 2011 and 2021. The average spending per prescription was calculated as a proxy for drug prices. Overall spending and utilization on ICIs have risen exponentially over the past decade. Between 2011 and 2021, expenditures increased from $2.8 million to $4.1 billion. Utilization increased from 94 prescriptions to 462,049 prescriptions in 2021 with six ICIs. The average spending per prescription, or average drug price, decreased 70%, from $29,795.88 in 2011 to $8914.69 in 2021. Spending on and utilization of ICIs have increased dramatically over the past decade. These findings shed new light on the impact of ICIs on state Medicaid programs and may provide insight into potential cost drivers that need to be addressed through policy.

Progress on neoadjuvant immunotherapy in resectable non-small cell lung cancer and potential biomarkers.

Immune checkpoint inhibitors (ICIs) are highly concerned in the treatment of non-small cell lung cancer (NSCLC), represented by inhibitors of programmed death protein 1 (PD-1) and its ligand (PD-L1), and inhibitors of cytotoxic T lymphocyte-associated antigen-4 (CTLA-4). The introduction of immunotherapy in the treatment of perioperative NSCLC has improved the prognosis to a great extent, as demonstrated by several phase II and III clinical trials. The target population for immunotherapy in early-stage NSCLC is still under discussion, and the biomarkers for neoadjuvant immunotherapy population selection are the next pending problem. The predictive efficacy of many potential makers is still being explored, including PD-L1 expression levels, tumor mutation burden, circulating tumor DNA, components of the tumor microenvironment, and several clinical factors. We summarize key findings on the utility of ICIs in clinical trials of preoperative NSCLC patients and conclude analyses of relevant biomarkers to provide a better understanding of potentially predictive biomarkers in neoadjuvant immunotherapy.

Expanding the applications of immune checkpoint inhibitors in advanced lung cancer beyond disease progression.

Immunotherapy, particularly the utilization of immune checkpoint inhibitors (ICIs), assumes a pivotal role in the comprehensive management of advanced lung cancer. There has been substantial deliberation regarding the appropriateness of extending ICIs treatment beyond the point of disease progression. This study delves into the potential benefits of sustained utilization of ICIs subsequent to disease progression in patients. A retrospective analysis was conducted on a cohort of 248 patients diagnosed with advanced lung cancer who received treatment with ICIs. The study population comprised 99 patients in the treatment beyond progression (TBP) group and 42 patients in the non-treatment beyond progression (NTBP) group. Parameters including progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and disease control rate (DCR) were assessed. The Cox proportional hazard regression model was employed to analyze prognostic factors related to immunotherapy. Patients undergoing primary treatment with PD-1/PD-L1 inhibitors exhibited a median progression-free survival (mPFS) of 5.3 months. In the context of disease progression, a comparison between the TBP and NTBP groups was performed with respect to mPFS. The results demonstrated that the TBP group manifested an mPFS of 8.6 months, contrasting with the NTBP group's mPFS of 4.0 months (p=0.028). The mean overall survival (mOS) in the TBP group exhibited a statistically significant increase in comparison to the NTBP group (14.1 months vs. 6.0 months, p=0.028). Evaluation of the objective response rate (ORR) between the TBP and NTBP groups revealed a substantial distinction. The TBP group displayed an ORR of 12.1%, while the NTBP group exhibited a lower ORR of 2.4%. The statistical analysis yielded a p-value of 0.068, signifying a notable trend towards significance. The disease control rate (DCR) was also assessed and exhibited a noteworthy variance between the two groups, with a higher DCR of 92.9% in contrast to 71.4% in the control group (p = 0.001). Subsequent to ICIs treatment, a subset of patients may derive continued benefits from anticancer therapy, notwithstanding the progression of their advanced lung cancer.

Targeting β-catenin and PD-L1 simultaneously by a racemic supramolecular peptide for the potent immunotherapy of hepatocellular carcinoma.

Objective: The low clinical utility of immune checkpoint inhibitors (ICIs) against PD-1 or PD-L1 has recently been associated with the activation of the Wnt/β-catenin signaling pathway in hepatocellular carcinoma (HCC), which promotes tumor immune escape and resistance to anti-PD-1/PD-L1 therapy. Hence, we aimed to fabricate a supramolecular peptide which could target the Wnt/β-catenin signaling pathway coupled with ICIs blockage therapy for optimizing HCC immunotherapy. Methods: A racemic spherical supramolecular peptide termed sBBI&PDP nanoparticle was constructed by hierarchical self-assembly, comprising an L-enantiomeric peptide as an inhibitor of BCL9 and β-catenin (sBBI) and a D-enantiomeric peptide as an inhibitor of PD-1/PD-L1 (PDP). Results: sBBI&PDP nanoparticle potently suppressed the hyperactivated Wnt/β-catenin signaling pathway in vitro and in vivo, while blocking endogenous PD-L1 effectively. Furthermore, sBBI&PDP increased the infiltration and action of CD8+ T cells at tumor sites. Notably, compared with the original sBBI and commercial Anti-PD-L1 inhibitors, the designed sBBI&PDP showed stronger antitumor efficacy in an orthotopic homograft mice model of HCC and a PDX HCC model in Hu-PBMC-NSG mice. Moreover, sBBI&PDP possessed a favorable biosafety profile. Conclusion: The successful implementation of this strategy could revitalize ICIs blockage therapy and promote the discovery of artificial peptides for HCC immunotherapy.

A Review of the Role of Stereotactic Radiosurgery and Immunotherapy in the Management of Primary Central Nervous System Tumors.

Stereotactic radiosurgery (SRS) and immune checkpoint inhibitors (ICIs) are widely used in the management of brain metastases. These therapies are commonly administered concurrently; as SRS may enhance anti-tumor immunity and responsiveness to ICIs. However, the use of ICIs with and without SRS in the management of primary brain tumors remains a controversial topic. Meningiomas are the most common nonmalignant and extra-parenchymal brain tumor, which often respond well to surgery and radiotherapy. However, higher grade meningiomas tend to be resistant to these treatments, and the use of chemotherapy and targeted agents in this setting have yielded disappointing results. Thus, there is heightened interest in the utilization of ICIs. Glioblastoma is the most common malignant primary intraparenchymal brain tumor. It is associated with a grim prognosis with a median overall survival of approximately 20 months, despite optimal therapy. While SRS in the adjuvant setting, and ICI in the recurrent setting, have failed to demonstrate a survival benefit, SRS in the preoperative setting has the potential to enhance anti-tumor immunity and responsiveness to ICIs. Thus, these treatments represent an attractive option to add to the armamentarium of meningioma and glioblastoma management. In this review, we provide a detailed overview of the evidence supporting the use of ICIs and SRS in each of these settings.

T cells specific for α-myosin drive immunotherapy-related myocarditis.

Immune-related adverse events, particularly severe toxicities such as myocarditis, are major challenges to the utility of immune checkpoint inhibitors (ICIs) in anticancer therapy1. The pathogenesis of ICI-associated myocarditis (ICI-MC) is poorly understood. Pdcd1-/-Ctla4+/- mice recapitulate clinicopathological features of ICI-MC, including myocardial T cell infiltration2. Here, using single-cell RNA and T cell receptor (TCR) sequencing of cardiac immune infiltrates from Pdcd1-/-Ctla4+/- mice, we identify clonal effector CD8+ T cells as the dominant cell population. Treatment with anti-CD8-depleting, but not anti-CD4-depleting, antibodies improved the survival of Pdcd1-/-Ctla4+/- mice. Adoptive transfer of immune cells from mice with myocarditis induced fatal myocarditis in recipients, which required CD8+ T cells. The cardiac-specific proteinα-myosin, which is absent from the thymus3,4, was identified as the cognate antigen source for three major histocompatibility complex class I-restricted TCRs derived from mice with fulminant myocarditis. Peripheral blood T cells from three patients with ICI-MC were expanded by α-myosin peptides. Moreover, these α-myosin-expanded T cells shared TCR clonotypes with diseased heart and skeletal muscle, which indicates that α-myosin may be a clinically important autoantigen in ICI-MC. These studies underscore the crucial role for cytotoxic CD8+ T cells, identify a candidate autoantigen in ICI-MC and yield new insights into the pathogenesis of ICI toxicity.

Inpatient utilization of immune checkpoint inhibitors and clinical outcomes.

Retrospective studies have suggested that patients with poor performance status treated with immune checkpoint inhibitors have shorter overall survival and poorer response rates. This study was undertaken to investigate the possible relationships between inpatient immune checkpoint inhibitor use and clinical outcomes. This was a retrospective chart review of cancer patients who received an immune checkpoint inhibitor while hospitalized from 1 January 2016 to 30 December 2020. The primary outcome was 90-day mortality or admission to hospice rate. Secondary outcomes included overall survival, time to death or discharge to hospice, and descriptive summarization of patient characteristics. A total of 52 patients were analyzed. At 90 days, 68.2% of subjects were expired or admitted to hospice (95% CI: 54.7-81%). 90-day overall survival was 47.1%; median survival time was 81 days (95% CI: 28-242 days). The median time to death or hospice was 35 days (95% CI: 24-72 days). The time to death or hospice was shorter for immune checkpoint inhibitor-naive patients compared to those who received immune checkpoint inhibitors prior to admission (29 days, 95% CI: 12-43 days vs. 242 days, 95% CI: 36-1288 days, respectively; HR: 2.74, 95% CI: 1.2-6.25; p = 0.0121). No differences were found when comparing other baseline characteristics. A majority of patients who received an immune checkpoint inhibitor while hospitalized were either discharged to hospice or expired by 90 days. An increased rate of death or discharge to hospice was observed for patients who were immune checkpoint inhibitor-naive prior to their admission.

Abstract 2577: ITI-214, a potent and selective PDE1 inhibitor, inhibits tumor growth when combined with a checkpoint inhibitor in a mouse model of breast cancer

Abstract Breast cancer is the most common cancer in women. Targeted therapies, such as hormonotherapy or immunotherapy, including checkpoint inhibitors, have revolutionized cancer treatment and are effective for most breast cancer patients. Unfortunately, some patients do not benefit from these therapies and development of resistance might lead to cancer progression in patients with primary clinical responses. Therefore, resistance to checkpoint inhibitor (e.g., PD-1/PD-L) blockade remains a significant challenge and impedes their broader application. To overcome this limitation, development of new therapeutic solutions to improve efficacy and clinical response is essential. We have demonstrated that a selective inhibitor (ITI-214) of the phosphodiesterase type 1 (PDE1) enzyme [Li et al. J Med Chem. 2016;59:1149] modulates immune cell function (microglia and macrophages) by altering cell migration and key cytokines (mainly CCL2 and TNF-α) [O’Brien et al. MCN. 2020;102:103449]. We hypothesized that ITI-214 will affect macrophage infiltration and polarization, as well as improve T cell recruitment and function into the tumor microenvironment, thereby promoting antitumor immunity in murine cancer models. Here we have tested this hypothesis by studying the effect of ITI-214, alone or in combination with sub-effective doses of a programmed cell death-1 (PD-1) immune checkpoint inhibitor, in a syngeneic mouse model of breast cancer. We measured effects of ITI-214 (+/-anti-PD-1 antibody, 10 mpk) on tumor growth, tumor microenvironment composition, and survival of E0771 tumor-bearing C57Bl/6 mice. Tumor growth in mice treated with ITI-214 or with anti-PD-1 antibody alone was similar to isotype control. However, significant inhibition of tumor growth was observed in mice receiving ITI-214 and anti-PD-1 in combination compared to control. Flow cytometry analysis of the tumor microenvironment showed no change in the number of tumor macrophages or T cells in the combination group, but significant shift in the polarization of macrophages toward a more inflammatory phenotype. Furthermore, RNAseq analysis of tumors treated with combination therapy showed a reduction in genes from pathways involved in cell cycle and proliferation and an increase in genes from inflammatory and immune response pathways. The results suggest that ITI-214, in combination with anti-PD-1 antibody, promotes antitumor immunity, leading to tumor growth inhibition. Furthermore, we have evidence that these observations are driven by tumor-associated macrophages. In conclusion, this study demonstrates a synergistic ability of ITI-214 and anti-PD-1 to alter the tumor microenvironment and control tumor growth in mice. Translating these findings to the clinic suggests that ITI-214 may provide a means to expand the utility of immune checkpoint inhibitors to treatment-refractory tumors. Citation Format: Maud Voisin, Stephen Goding, Gretchen L. Snyder, Robert E. Davis. ITI-214, a potent and selective PDE1 inhibitor, inhibits tumor growth when combined with a checkpoint inhibitor in a mouse model of breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2577.

Abstract 48: Molecular characteristics of HRAS mutated non-small cell lung cancer (NSCLC)

Abstract Background: Alterations in the RAS pathway have been linked to tumorigenesis, apoptosis, metabolism and angiogenesis. Mutations of KRAS in NSCLC are more frequent and better characterized, however, other family members such as HRAS remain under investigated and RAS remains a challenging therapeutic target. HRAS has been indirectly targeted with tipifarnib, a farnesyltransferase inhibitor rendering HRAS inactive in head and neck tumors. Here, we characterize the incidence, genomic landscape, and clinical context of HRAS alterations in NSCLC. Methods: A total of 29,767 NSCLC tumor samples underwent comprehensive molecular profiling at Caris Life Sciences. Analyses included next generation sequencing of DNA (592 Gene Panel, NextSeq, or whole exome sequencing, NovaSeq), RNA (NovaSeq, whole transcriptome sequencing, WTS) and immunohistochemistry. MAPK activation was assessed using the MPAS gene expression signature. Wilcoxon, Fisher’s exact, or Dunnett’s tests were used to determined statistical significance (displayed as p value without and q value with multi-comparison correction). Overall survival was calculated from date of tissue collection to last contact from insurance claims data and used for Kaplan-Meier analysis. Comparisons were conducted between HRAS mutated tumors and the entire NSCLC general cohort (GC). Results: HRAS mutations (Hm) were detected in 128 of 29767 NSCLC samples (0.4%) and were significantly enriched in older patients (median age, 71 vs. 69 years; q<0.01) and squamous histology (57.8% vs 21.8%, q<0.0001) compared to GC. Smoking status was not associated with HRAS mutational status (p=0.19). The most prevalent loci of hotspot mutations in Hm tumors were G13 (42.2%), followed by Q61 (33.6%) and G12 (21.1%). HRAS was not prognostic for overall survival (HR = 1.06, 95% CI [0.83-1.35], p=0.64), but for HRAS G13 mutant subset of NSCLC there was a trend towards worse prognosis (HR = 1.31, 95% CI [0.91-1.88], p =0.14). Hm-positive tumors harbored significantly more PIK3CA mutations (16.9% vs 5.5%, q<0.05) but less KRAS (3.2% vs 27.4%, q<0.05) and EGFR mutations (0.8% vs 11.9%, q<0.05) compared to GC. In addition, Hm displayed dMMR/MSI deficiency (2.6% vs 0.7%, p <0.05) more frequently, but had a comparable percentage of TMB-H tumors (34.2% vs 40.2%, p = 0.16) and similar median PD-L1 expression (54.7% vs 60.3%, p = 0.21) when comparing to GC. Lastly, MAPK pathway activation score was relatively higher in Hm compared to GC (-0.26 vs -0.42) with Q61 being the highest group (0.04 vs -0.42, p = 0.37). Conclusions: HRAS mutations are detectable but uncommon events in NSCLC and significantly enriched in squamous histology. HRAS mutations often occur with PIK3CA co-mutations and trended towards higher activation of MAPK pathway and MSI-H frequency. This warrants further investigation on possible clinical applications of HRAS pathway inhibitors and utility of immune checkpoint inhibitors for this subset of NSCLC. Citation Format: Asaad Trabolsi, Estelamari Rodriguez, Samuel Alexander Kareff, Michael Korn, Joanne Xiu, Stephen Liu, Philip walker, Patrick Ma, Hirva Mamdani, Jorge Nieva, Hossein Borghaei, Chadi Nabhan, Misako Nagasaka, Sonam puri, Gilberto Lopes. Molecular characteristics of HRAS mutated non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 48.

Abstract 1220: Accurately genotyping HLA and KIR alleles using cfDNA assay and k-mer based algorithm for immunotherapy

Abstract Background: HLA and KIR genotypes show great promise as emerging biomarkers for immune checkpoint inhibitors (ICIs) and understanding patient prognosis. Multiple studies have shown that HLA-I heterozygosity and high sequence divergence across alleles positively correlates with response to ICIs. However the high degree of polymorphism and allele sequence similarities in HLA and KIR present a challenge to accurate allele calling. To address these difficulties we developed kmerizer, a novel allele caller optimized for short fragments, such as reads from a cfDNA assay. Methods: We tested kmerizer on MHC class1 and class2 genes, and on KIR genes, on both simulated datasets and real samples (cell lines and plasma samples). To assess the capability of the algorithm to distinguish highly homologous allele pairs, we simulated cfDNA-like fragments with errors on randomly selected allele pairs, and on allele pairs with a high level of homology. Twelve plasma samples and 19 reference cell lines fragmented to cfDNA size were analyzed using a NGS cfDNA assay. For plasma samples, paired buffy coats were sent to an external vendor for HLA typing using multiplex PCR-based amplicon and sequenced by 300bp paired-end reads. Results: Of the 19 cell lines and 12 plasma samples for HLA typing (A, B, C, and DQB1 loci), kmerizer delivered 100% sensitivity with 98% specificity. On the simulated dataset, kmerizer achieved 99% sensitivity and specificity on all the MHC class1 and class 2 loci, and 90% sensitivity and specificity on all KIR loci, for both homozygous and heterozygous pairs. The novel allele caller kmerizer also demonstrated a lighter footprint on computational resource need: one deep-sequencing plasma sample on average can be processed in less than 2 minutes which is about 15 times faster than the most commonly used HLA typing tool HISAT21, which does not support KIR typing. Conclusions: As utilization of ICIs increases, the use of genetic and genomic information to accurately identify patients more likely to respond to ICIs will be critical. kmerizer is a fast and highly sensitive and specific allele caller, and it can effectively call alleles on both HLA and KIR.

Immunotherapy in Lung Cancer: Current Landscape and Future Directions.

Over the past decade, lung cancer treatment has undergone a major paradigm shift. A greater understanding of lung cancer biology has led to the development of many effective targeted therapies as well as of immunotherapy. Immune checkpoint inhibitors (ICIs) have shown tremendous benefit in the treatment of non-small cell lung cancer (NSCLC) and are now being used as first-line therapies in metastatic disease, consolidation therapy following chemoradiation in unresectable locally advanced disease, and adjuvant therapy following surgical resection and chemotherapy in resectable disease. Despite these benefits, predicting who will respond to ICIs has proven to be difficult and there remains a need to discover new predictive immunotherapy biomarkers. Furthermore, resistance to ICIs in lung cancer is frequent either because of a lack of response or disease progression after an initial response. The utility of ICIs in the treatment of small cell lung cancer (SCLC) remains limited to first-line treatment of extensive stage disease in combination with chemotherapy with modest impact on overall survival. It is thus important to explore and exploit additional targets to reap the full benefits of immunotherapy in the treatment of lung cancer. Here, we will summarize the current state of immunotherapy in lung cancer, discuss novel targets, and explore the intersection between DNA repair defects and immunotherapy.

Management of Patients with Malignant Peritoneal Mesothelioma: The Evolving Role of Surgery and Immunotherapy

Malignant peritoneal mesothelioma, a neoplastic process that arises from the peritoneal membranes and presents as a diffuse malignant process, has an incidence of approximately 400-600 new cases annually in the United States. Systemic chemotherapy regimens, like the combination of cisplatin and pemetrexed, have response rates of approximately 25% in peritoneal mesothelioma. Due to chemotherapy’s poor response rates, the first line approach to treating malignant peritoneal mesothelioma over the last 30 years has been surgical resection with regional intra-peritoneal chemotherapy in appropriately selected patients. Hyperthermic intraoperative intraperitoneal perfusion with chemotherapy with cisplatin or mitomycin c for 90 to 120 minutes is the most commonly reported type of regional chemotherapy that is administered during surgical cytoreduction. Favorable prognostic factors for patient outcomes after cytoreduction and hyperthermic intraperitoneal perfusion with chemotherapy tend to be favorable operative characteristics (lower peritoneal cancer index, better complete cytoreduction score), less aggressive tumor characteristics (epithelioid histology, low Ki-67, well-differentiated), and other patient characteristics (young, female, fewer comorbidities). Recently, there has been considerable interest in the utility of immune checkpoint inhibitors either alone or in combination with chemotherapy for patients with mesothelioma. Data demonstrate that programmed death-ligand 1 may be highly expressed in a large proportion of malignant peritoneal mesothelioma tumors and therefore the evaluation of checkpoint blockade in this patient population is a high clinical priority.