Immune Checkpoint Inhibitors Targeting Research Articles

Immune-checkpoint inhibitor-mediated myocarditis: CTLA4, PD1 and LAG3 in the heart.

Immune-checkpoint inhibitors (ICIs) have revolutionized oncology, with nearly 50% of all patients with cancer eligible for treatment with ICIs. However, patients on ICI therapy are at risk for immune-related toxicities that can affect any organ. Inflammation of the heart muscle, known as myocarditis, resulting from ICI targeting cytotoxic Tlymphocyte-associated antigen 4 (CTLA4), programmed cell death protein 1 (PD1) and PD1 ligand 1 (PDL1) is an infrequent but potentially fatal complication. ICI-mediated myocarditis (ICI-myocarditis) is a growing clinical entity given the widespread use of ICIs, its increased clinical recognition and growing use of combination ICI treatment, a well-documented risk factor for ICI-myocarditis. In this Review, we approach ICI-myocarditis from a basic and mechanistic perspective, synthesizing the recent data from both preclinical models and patient samples. We posit that mechanistic understanding of the fundamental biology of immune-checkpoint molecules may yield new insights into disease processes, which will enable improvement in diagnostic and therapeutic approaches. The syndrome of ICI-myocarditis is novel, and our understanding of immune checkpoints in the heart is in its nascency. Yet, investigations into the pathophysiology will inform better patient risk stratification, improved diagnostics and precision-based therapies for patients.

Immune-checkpoint inhibitor-mediated myocarditis: CTLA4, PD1 and LAG3 in the heart.

Immune-checkpoint inhibitors (ICIs) have revolutionized oncology, with nearly 50% of all patients with cancer eligible for treatment with ICIs. However, patients on ICI therapy are at risk for immune-related toxicities that can affect any organ. Inflammation of the heart muscle, known as myocarditis, resulting from ICI targeting cytotoxic Tlymphocyte-associated antigen 4 (CTLA4), programmed cell death protein 1 (PD1) and PD1 ligand 1 (PDL1) is an infrequent but potentially fatal complication. ICI-mediated myocarditis (ICI-myocarditis) is a growing clinical entity given the widespread use of ICIs, its increased clinical recognition and growing use of combination ICI treatment, a well-documented risk factor for ICI-myocarditis. In this Review, we approach ICI-myocarditis from a basic and mechanistic perspective, synthesizing the recent data from both preclinical models and patient samples. We posit that mechanistic understanding of the fundamental biology of immune-checkpoint molecules may yield new insights into disease processes, which will enable improvement in diagnostic and therapeutic approaches. The syndrome of ICI-myocarditis is novel, and our understanding of immune checkpoints in the heart is in its nascency. Yet, investigations into the pathophysiology will inform better patient risk stratification, improved diagnostics and precision-based therapies for patients.

Disruption of the PGE2 synthesis / response pathway restrains atherogenesis in programmed cell death-1 (Pd-1) deficient hyperlipidemic mice.

Immune checkpoint inhibitors (ICIs) that target programmed cell death 1 (PD-1) have revolutionized cancer treatment by enabling the restoration of suppressed T-cell cytotoxic responses. However, resistance to single-agent ICIs limits their clinical utility. Combinatorial strategies enhance their antitumor effects, but may also enhance the risk of immune related adverse effects of ICIs. Prostaglandin (PG) E2, formed by the sequential action of the cyclooxygenase (COX) and microsomal PGE synthase (mPGES-1) enzymes, acting via its E prostanoid (EP) receptors, EPr2 and EPr4, promotes lymphocyte exhaustion, revealing an additional target for ICIs. Thus, COX inhibitors and EPr4 antagonists are currently being combined with ICIs potentially to enhance antitumor efficacy in clinical trials. However, given the cardiovascular (CV) toxicity of COX inhibitors, such combinations may increase the risk particularly of CV AEs. Here, we compared the impact of distinct approaches to disruption of the PGE2 synthesis /response pathway - global or myeloid cell specific depletion of mPges-1 or global depletion of Epr4 - on the accelerated atherogenesis in Pd-1 deficient hyperlipidemic (Ldlr-/-) mice. All strategies restrained the atherogenesis. While depletion of mPGES-1 suppresses PGE2 biosynthesis, reflected by its major urinary metabolite, PGE2 biosynthesis was increased in mice lacking EPr4, consistent with enhanced expression of aortic Cox-1 and mPges-1. Deletions of mPges-1 and Epr4 differed in their effects on immune cell populations in atherosclerotic plaques; the former reduced neutrophil infiltration, while the latter restrained macrophages and increased the infiltration of T-cells. Consistent with these findings, chemotaxis by bone-marrow derived macrophages from Epr4-/- mice was impaired. Epr4 depletion also resulted in extramedullary lymphoid hematopoiesis and inhibition of lipoprotein lipase activity (LPL) with coincident spelenomegaly, leukocytosis and dyslipidemia. Targeting either mPGES-1 or EPr4 may restrain lymphocyte exhaustion while mitigating CV irAEs consequent to PD-1 blockade.

Pervasive loss of antigen presentation in solid tumors driven by loss of HLA class I expression.

e14654 Background: Human Leukocyte Antigens (HLA) play a key role in inducing responses to immune checkpoint inhibitor (ICI) therapy. HLA class I (HLA-I) expression is essential for antigen presentation in cancer cells and its loss leads to immune evasion. Expression of HLA-II shows presence of adaptive immune response via antigen presenting cells. To investigate the complex interplay of HLA class I/II in solid tumors, we study the landscape and association of several HLA phenotypes with biomarkers of tumor response and resistance to ICIs in a large pan-cancer cohort. Methods: A real-world cohort of 24,186 solid tumors was assessed by an immune expression profiling assay of 395 genes that were background subtracted, normalized, and ranked yielding a percentile rank value [0-100]. HLA Class I and class II expressions were estimated as average expression of HLA-A, HLA-B, HLA-C genes, and HLA HLA-DP, HLA-DQ, HLA-DR genes, respectively. Both HLA classes were labelled as high (≥66), moderate (≥33 & <66) or low (<33). We studied the distribution of HLA I/II phenotype defined as Ihi/IIhi comprised hot tumors with no loss of HLA-I and Ilo/IIhi defines immune evasion via loss of HLA-I in hot tumors. Ihi/IIlo phenotype comprises less inflamed tumors with high HLA-I expression and Ilo/IIlo comprises of cold tumors. We also performed differential expression of ICI targets including PD-1, PD-L1, LAG-3, TIM3 and expression-based signatures of inflammation and cell proliferation. Results: Loss of HLA-I expression was observed in 44.1% (n= 10669) of all solid tumors with most frequent loss observed in prostate (55%, n=450) cancer. Similarly, loss of HLA-II expression was observed in 34.7% (n=8396) of solid tumors with highest loss observed in neuroendocrine (59%; n=345) cancers. 49% of all tumors presented with four HLA-phenotypes, where 17.9% (n=4332) were characterized by Ilo/IIlo phenotype. Ihi/IIlo was present in 13% (n=3127) of all tumors. Both Ihi/IIhi and Ilo/IIhi phenotypes were significantly (p<0.001) associated with increased tumor inflammation. Other ICI targets such as PD-L1, TIM3, CTLA4 and LAG3 were significantly (p<0.001) overexpressed in this immune evasion phenotype compared to other phenotypes. Conversely, Ilo/IIlo phenotype was significantly associated with cold tumors (p<0.001), hinting at lack of adaptive immune response in these tumors. Conclusions: This study offers insight into pervasive loss of antigen presentation via HLA expression. Concurrent loss of HLA Class I expression with increased class II expression and additional ICI target co-expression is a potential immune escape mechanism in immunologically active solid tumors. Distinct and significant association of these MHC phenotypes with tumor inflammation, checkpoint markers and PD-L1 highlight the potential use of comprehensive immune profiling for further studying combination strategies to correct soft loss of HLA-I and ICI therapies.

Outcomes following long-term response to immune checkpoint inhibitors in patients with advanced melanoma.

9520 Background: Immune checkpoint inhibitors (ICI) targeting PD-1 and CTLA-4 can achieve durable responses. Historically, therapies in advanced malignancies were considered palliative, however long-term results from ICI melanoma studies suggest cure may be possible for some patients (pts). Despite clinical trial data, little is known about the risk, character, and clinical outcome of late recurrences after ICI. Methods: ICI treated pts with advanced melanoma who had a long-term disease control, defined as not requiring a subsequent line of systemic therapy within 3 years, were retrospectively identified at 11 centres. Those who had progressive disease managed with local therapies were included if no new systemic therapy was commenced within the 3 years. Demographics, disease characteristics, treatment, toxicity, recurrence patterns, management and outcomes were collected. Results: 567 pts were identified, with a median follow up of 7 years since start of therapy. At ICI commencement, 41% and 17% had M1c or M1d disease respectively, 26% had an elevated LDH, 33% were BRAF mutant and 24% had received prior therapy. The ICIs received were anti-PD-1 +/- an investigational agent (59.3%), anti-PD-1 plus anti-CTLA-4 (35.8%), or an anti-CTLA-4 (5%). The median duration of therapy was 18 months, with 31% of pts stopping due to toxicity. 63 pts (11.1%) had oligo-progression within 3 years from ICI start. 53 pts (9.3%) had progression after 3 years, with median time to progression of 16.3 months. Subsequent late progression was more common in those who had oligo-progression within 3 years of treatment compared to those who had not (14/63, 22% vs 39/504, 7.7%, P<0.001). The risk of late progression was lower in those who achieved a complete response (CR) compared to those without a CR (23/369, 6.2% vs 30/198, 15.2%, P<0.001). The landmark 5 year PFS was 95% compared to 89% in those with or without a CR respectively. Duration of therapy, treatment cessation due to toxicity, or corticosteroid use were not associated with the risk of late progression. Most late progression occurred within year 3 to 5 (38/53, 72%). 15 pts who progressed after 3 years were managed with local therapy alone. In progressors retreated with PD-1 alone as the next subsequent therapy, 14 of 26 (54%) responded (7 CR, 7 PR). In the total cohort, there were 31 (5.5%) deaths, 7 (1.2%) from melanoma. Of the pts with a CR, 14 (3.7%) died, only 1 (0.3%) from melanoma. Of the 53 pts who progressed after 3 years, 10 (19%) died, 7 (13%) from melanoma. Conclusions: In this population of pts with advanced melanoma with long term disease control from ICI, the risk of subsequent disease progression and death was low (1.2%). Predictors for late progression after 3 years were a non-CR best response and prior progression within 3 years. This and other data suggest a significant proportion of long-term ICI responders are likely cured, and may inform frequency and duration of follow up.

Retro TIMing: A multicentric retrospective analysis of immunotherapy timing in metastatic melanoma.

9542 Background: Immune checkpoint inhibitors (ICI) targeting programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) are now the standard of care in the treatment of metastatic melanoma (mM). The interplay between cancer cells and tumor microenvironment cells (e.g. immune cells) impacts cancer cell survival, local invasion, and metastatic dissemination. Chrono-immunotherapy is an emerging field as circadian oscillations are observed in the immune landscape (e.g immune cell numbers) as well as in the expression of immunotherapy targets (e.g. PD-1). Recently, a growing body of evidence suggests the outcome can be influenced by the time of the day when immunotherapy is administered (morning versus in the afternoon). This work aims to evaluate the impact of immunotherapy with ICIs administration timing on the overall survival (OS) and progression-free survival (PFS) of patients with mM. Methods: Multicentric, retrospective cohort study of mM patients under immunotherapy (ipilimumab/nivolumab, nivolumab, or pembrolizumab) with PS 0-1, between July 2016 and June 2023. Clinical, demographic characteristics, and time of treatment administration were obtained from medical records. Patients were distributed in two groups: those who received less than 75% of infusions after 2pm (morning group), and those who received at least 75% of infusions after 2pm (afternoon group). OS and PFS were calculated with Kaplan-Meier method and tested using a Cox regression model, with a 95% confidence interval. Results: We identified 168 patients from the 7 Oncology Centers included. The majority were men (n=100, 59.5%), with a median age of 69 years old, and 22% of the patients (n=37) were included in the afternoon group. No significant demographic or tumor burden differences were found between the morning and afternoon groups. The median follow-up time was 29 months, the estimated median PFS was 11.8 months (CI 95%, 8.0 - 14.6) and median OS was 31.4 months (CI 95%, 20.6 - NR). Patients in the afternoon group presented with shorter OS compared with those in the morning group (14.4 vs 37.6 months; HR 1.94 [CI 95% 1.16 to 3.23]; p 0,014). No statistically significant differences were observed in PFS. Subgroup analysis showed an increased detriment of performing ICIs infusions in the afternoon in women (OS 8.7 (4.2, 21.2) versus 30.9 months (18.9, NR), p=0.002; afternoon versus morning) and those older than 65 years old (OS 14.2 months (4.7, 31.4) versus 24.2 months (18.3, NR), p=0.002); afternoon versus morning). Conclusions: This work provides valuable insights into the potential role of the circadian timing of immunotherapy treatments for mM, suggesting patients may benefit from having ICIs infusion in the morning. Prospective randomized studies with a translational approach are needed to validate and fully understand the underlying mechanisms at play in circadian timing efficacy.

Correlation of previous local vaccination site “flares” during immunotherapy for metastatic melanoma with complete responses to therapy.

e21534 Background: mRNA vaccines have been shown to stimulate T-cells targeting patient-specific tumor neoantigens. When combined with immune checkpoint inhibitors (ICI) in a randomized Phase II trial, mRNA vaccines demonstrated improvement in recurrence free survival and distant metastasis free survival compared to ICI alone. We retrospectively examined patients (pts) with advanced melanoma treated more than 5 years ago on clinical trials with adjuvant NYESO1 or mRNA vaccine therapies (VT) then ICI upon recurrence and analyzed biomarkers correlating with treatment response. Methods: This retrospective study examined 22 pts with advanced melanoma treated between 2004-2017 with adjuvant vaccine therapies (VT). 10 of the 22 pts subsequently developed recurrent disease and were treated with ICI. We evaluated disease free interval following ICI, sex, age, BRAF status, HLA type, site of primary and metastatic disease, initial vaccine treatment, vaccine toxicities, stage and sites of melanoma recurrence, ICI treatment, response and toxicities, vaccine site flares or cutaneous immune related adverse events (irAEs) following ICI. Results: Of the 22 patients (11 male, 11 female) treated with adjuvant VT, median age at first vaccine was 53 years old. HLA type was known for 11 pts. Stage at initial VT was IIB to IIIC. 14 pts recurred following adjuvant VT. Median time from vaccine initiation to melanoma recurrence was 3.2 years (range 6.5 months to 11 years). 10 pts received ICI for recurrent melanoma, 3 pts received ipilimumab, 2 anti-PD1 monotherapy, 4 ipilimumab and nivolumab, and 1 nivolumab/relatlimab. Stage at first ICI was IIIB to IV M1d. 9 pts experienced cutaneous irAEs. 7 pts experienced local vaccine site flare reactions following ICI treatment. Additionally, 2 pts experienced vitiligo, 2 with dermatologic flares (bullous pemphigoid and psoriatic rash), 2 with generalized rash that resolved with steroid cream. 1 pt did not experience rash, vaccine site flare, nor irAE dermatologic flare. Of the pts who recurred, 2 pts had BRAF V600E mutations, and 1 of these pts experienced vaccine flare, the other did not. 1 pt with a BRAF Q16L mutation did not have vaccine flare. 6 out of 7 BRAF wild type pts who recurred and received ICI experienced a localized vaccine site flare. Median disease-free interval following ICI treatment was 1.5 years (range 3 months to 9 years). All 10 pts are disease-free and off ICI being closely monitored. Conclusions: Evidence of prior localized vaccination “flare” may be a biomarker for a complete immunologic response in pts with metastatic disease treated with immunotherapy. ICI targeting CTLA-4 and/or PD-1 both triggered this localized vaccination site response, suggesting that T cell memory and immunologic activation against melanoma antigens translate into clinical responses.

Immune checkpoint inhibitors: breakthroughs in cancer treatment.

Over the past two decades, immunotherapies have increasingly been considered as first-line treatments for most cancers. One such treatment is immune checkpoint blockade (ICB), which has demonstrated promising results against various solid tumors in clinical trials. Monoclonal antibodies (mAbs) are currently available as immune checkpoint inhibitors (ICIs). These ICIs target specific immune checkpoints, including cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) and programmed cell death protein 1 (PD-1). Clinical trial results strongly support the feasibility of this immunotherapeutic approach. However, a substantial proportion of patients with cancer develop resistance or tolerance to treatment, owing to tumor immune evasion mechanisms that counteract the host immune response. Consequently, substantial research focus has been aimed at identifying additional ICIs or synergistic inhibitory receptors to enhance the effectiveness of anti-PD-1, anti-programmed cell death ligand 1 (anti-PD-L1), and anti-CTLA-4 treatments. Recently, several immune checkpoint molecular targets have been identified, such as T cell immunoreceptor with Ig and ITIM domains (TIGIT), mucin domain containing-3 (TIM-3), lymphocyte activation gene-3 (LAG-3), V-domain immunoglobulin suppressor of T cell activation (VISTA), B and T lymphocyte attenuator (BTLA), and signal-regulatory protein α (SIRPα). Functional mAbs targeting these molecules are under development. CTLA-4, PD-1/PD-L1, and other recently discovered immune checkpoint proteins with distinct structures are at the forefront of research. This review discusses these structures, as well as clinical progress in mAbs targeting these immune checkpoint molecules and their potential applications.

Abstract PO1-25-12: Metformin enhances response to chemotherapy combined with immunotherapy in a triple negative breast cancer in vivo model

Abstract Background Triple-negative breast cancer (TNBC) is a heterogeneous group comprising several well-defined molecular subtypes. Classical chemotherapy remains the standard of care for advanced TNBC, although blockade of the PD-1/PD-L1 axis has emerged as a promising therapeutic option to enhance antitumor immunity. Atezolizumab is an immune checkpoint inhibitor targeting PD-L1 that has been approved for use in combination with paclitaxel for the treatment of advanced TNBC. Metformin (MTF) is a prescribed drug for type 2 diabetes with well-tolerated side-effects and has been reported to have anticancer effects. Xenograft mouse models studies of breast, lung and prostate cancer, have reveal a synergistic effect of MTF when combined with paclitaxel, carboplatin or doxorubicin and has been reported to enhance the efficacy of immunotherapy. In this work we want to explore the effect of including MTF in a chemo-immunotherapy scheme using an in vivo model. Methods 1x106 EMT6 TNBC cell line (ATCC® CRL-2755™) were implanted subcutaneously in the back of immunocompetent BALB/c mice. Treatment began when tumours reached a volume size of 30-100 mm3. At that moment, mice received the drug, or drugs combinations, for 21 days. All drugs were administered intraperitoneally, except for MTF, which was given orally in drinking water at a concentration of 1g/L. The anti PD-L1 drug anti-hPD-L1-mIgG1 (mATZ, 300 mg/week) was administered twice per week and doxorubicin (DOXO) every three days (0.3 mg/Kg or 6 mg/kg). The primary outcome will be tumour response. Tumour size was measured using a digital caliper every day until mice were euthanized. For tumour volume determination (mm3), two measures were taken (length and width). Volume was calculated as (length x wide2)/2. We tested three different arms: DOXO(0,3mg/Kg)+m-ATZ, DOXO(0,3mg/Kg)+m-ATZ+MTF, and DOXO(6mg/Kg)+m-ATZ. Each arm included 10 mice. Differences in tumour volume and mice weight were assessed by Kruskall-Wallis analysis. Results EMT6 cells produced a tumour mass in twenty seven out of thirty mice. Follow-up in mice in the DOXO(0.3mg/Kg)+m-ATZ and DOXO(6mg/Kg)+m-ATZ arms was interrupted in two weeks due to extended tumour growth and quality of live criteria, respectively. Mice in the DOXO(0.3mg/Kg)+m-ATZ+MTF arm were followed for three weeks. Increase of tumoral volume was assessed at 14 days. Mean increase was 205, 1096 and 365 mm3in the DOXO(6mg/Kg)+m-ATZ, DOXO(0,3mg/Kg)+m-ATZ, and DOXO(0,3mg/Kg)+m-ATZ+MTF arms respectively, being the volume increase between DOXO(0,3mg/Kg)+m-ATZ treated mice significantly higher. Regarding mice, mean weight at the beginning of the treatments was 19.8 gr for the complete mice population, whereas mean weight after 14 days of treatment was 15.4, 20.9 and 21.7 gr in the DOXO(6mg/Kg)+m-ATZ, DOXO(0,3mg/Kg)+m-ATZ, and DOXO(0,3mg/Kg)+m-ATZ+MTF arms respectively, showing a significant decrease of body weight in mice receiving a high dose of DOX, while no differences associated to the inclusion of MTF in the treatment scheme was found. Conclusions MTF addition to a combination of chemotherapy and immunotherapy in the treatment of TNBC increased therapy efficacy, with no added side effects. These result paves the way to explore treatment schemes with lower chemotherapy doses, decreasing toxicity side effects. Citation Format: Pilar Zamora, Angelo Gamez Pozo, Luz Vega-Clemente, Elena Lopez-Camacho, Lucia Trilla-Fuertes, David Alonso-Martin, Juan Angel Fresno Vara, Mariano Garcia-Arranz, Enrique Espinosa. Metformin enhances response to chemotherapy combined with immunotherapy in a triple negative breast cancer in vivo model [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 PO1-25-12.

Abstract 7525: Investigating B7-H3 as a checkpoint and antibody drug conjugate target across prostate cancer variants- both androgen receptor dependent and independent

Abstract Background: CD276 (B7-H3) has recently emerged as a promising presumptive immune checkpoint inhibitor (ICI) and antibody-drug conjugate (ADC) target for PCa. Unfortunately, current immunotherapy trials have yielded few objective responses in PCa and hormonal therapy seldom cures necessitating the need to develop new immunotherapy or targeted antibody-drug conjugate (ADC) treatment options for PCa, including B7-H3 targeted approaches. Method: In this work, we evaluated important ADC targets and immune checkpoints (PD-1, PD-L1, PD-L2, LAG3, TIGIT, OX40, 4-1BB, CTLA4, STEAP1, STEAP2, PSMA, NECTIN1, TROP-2, DLL3 and B7-H3) in various PCa cell lines and multiple patients spanning various subtypes of PCa using publicly available bulk RNA sequencing data and single-cell RNA sequencing (scRNA-seq) data respectively. The results were validated at RNA and protein levels in listed cell lines. Further, the impact of androgen receptor (AR) signaling on B7-H3 expression was quantified using charcoal stripped media, AR agonist (R1881) and antagonist (enzalutamide) using real-time PCR and flow cytometry at RNA and protein levels respectively. Results: We found that B7-H3 shows high expression and very low variability compared to other ADC targets and immune checkpoints in AR-positive (LnCAP), hormone-refractory (VCAP), Castrate resistant (22RVI), AR negative (PC3, DU145), and neuroendocrine (H660) cell lines, as well as in—PCa cells and tumor microenvironment (TME) myeloid cells—of multiple patients spanning various subtypes of PCa. Western blotting confirms the ubiquitous presence of B7-H3 in all these cell lines, even when PSMA is absent. Furthermore, B7-H3 expression was modifiable via androgen depletion, R1881 supplementation, or addition of the AR antagonist enzalutamide. These changes were significant in AR-positive LnCAP cells compared to AR-negative DU145 cells further endorsing the crosstalk between AR and B7-H3 signaling pathways, which will be presented in greater detail. Conclusion: This work explores the therapeutic relevance of important ADC targets and immune checkpoints for Prostate Cancer (PCa), highlighting B7-H3 as a unique therapeutic ADC and ICI candidate across the continuum of PCa—androgen sensitive, castration resistant, and neuroendocrine—due to its stable expression across various subtypes and on TME myeloid cells. The relationship between AR and B7-H3 opens the possibility of future combination therapies based on this interaction. Citation Format: Nikita Mundhara, Shivang Sharma, Emirhan Tekoglu, Ezra G. Baraban, Nathan A. Lack, Eugene Shenderov. Investigating B7-H3 as a checkpoint and antibody drug conjugate target across prostate cancer variants- both androgen receptor dependent and independent [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7525.

Abstract 4027: From tumor progression to therapeutic control: Combinatorial targeting of immune vulnerabilities in TNBC

Abstract Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer, associated with limited treatment options and high mortality rates. Although immune checkpoint inhibitors (ICIs) show promise, early clinical results indicate benefits in only a specific subset of patients with TNBC. Preclinical evidence indicates that infiltrating macrophages contribute to breast tumor progression by restricting CD8+ T cell infiltration, activation, and cytotoxicity within tumor microenvironments. Preliminary data has revealed that immune-competent mammary tumor-bearing MMTV-PyMT transgenic mice have slowed tumor progression following sequential combination of a microtubule poison (paclitaxel; PTX) to enhance tumor immunogenicity, plus a macrophage-depleting/reprogramming agent such as a colony-stimulating factor 1 receptor blocking antibody (αCSF1R), and undergo primary tumor regression in 60% of transgenic mice when an ICI targeting PD-1 is applied (3x therapy) by a CD8+ T cell-dependent mechanism. Response to 3x therapy is associated with localized CD8+ T effector and resident memory cell expansion, and increased antigen-specific clonal expansion at primary tumor sites. We hypothesized that epigenetic plasticity was limiting T cell memory and thus impeding long-term tumor control. Using a class 1 benzamide histone deacetylase (HDAC) inhibitor (e.g., entinostat) sequentially added to PTX/αCSF1R/αPD-1 therapy (4x) resulted in primary tumor stasis in 100% of mice, and significantly enhanced overall survival, in two transgenic mouse models of breast cancer (MMTV-PyMT and C3-(1)-TAg). Cohorts were analyzed at distinct time points for primary and metastatic tumor burden, in addition to immunophenotyping (flow cytometry), transcriptional (bulk and scRNA-Seq), epigenetic (sciATAC-Seq), and T cell receptor (TCR) changes correlating with 4x responses. Improved outcome and tumor stasis was associated with increased presence of long-lived central and stem-like memory CD8+ T cell infiltration, intra-tumoral B memory cell, and CD4+ T follicular helper cell infiltration. Tumor stasis was achieved by B and T cell-dependent mechanisms where B cell depletion led to decreased T cell cytotoxicity. Adoptive serum transfer (AST) from 4x-treated MMTV-PyMT mice into either 3x-treated or untreated MMTV-PyMT mice elicited tumor stasis and control. These preclinical studies indicate the complexity of myeloid, B cell and T cell interactions that are co-opted by tumors, and identify novel paths to therapeutic tumor control by targeting vulnerable immune communication programs. Citation Format: Amanda Poissonnier, Eivind Valen Egeland, Wesley Horton, Shamilene Sivagnanam, Orian Stapleton, Rossin Erbe, Nell Kirchberger, Konjit Betre, Alyza Skaist, Ludmila Danilova, Andrew Fields, Peter Ordentlich, Andrew C. Adey, Elana J. Fertig, Lisa M. Coussens. From tumor progression to therapeutic control: Combinatorial targeting of immune vulnerabilities in TNBC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4027.

The Use of Immune Regulation in Treating Head and Neck Squamous Cell Carcinoma (HNSCC).

Immunotherapy has emerged as a promising new treatment modality for head and neck cancer, offering the potential for targeted and effective cancer management. Squamous cell carcinomas pose significant challenges due to their aggressive nature and limited treatment options. Conventional therapies such as surgery, radiation, and chemotherapy often have limited success rates and can have significant side effects. Immunotherapy harnesses the power of the immune system to recognize and eliminate cancer cells, and thus represents a novel approach with the potential to improve patient outcomes. In the management of head and neck squamous cell carcinoma (HNSCC), important contributions are made by immunotherapies, including adaptive cell therapy (ACT) and immune checkpoint inhibitor therapy. In this review, we are focusing on the latter. Immune checkpoint inhibitors target proteins such as programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) to enhance the immune response against cancer cells. The CTLA-4 inhibitors, such as ipilimumab and tremelimumab, have been approved for early-stage clinical trials and have shown promising outcomes in terms of tumor regression and durable responses in patients with advanced HNSCC. Thus, immune checkpoint inhibitor therapy holds promise in overcoming the limitations of conventional therapies. However, further research is needed to optimize treatment regimens, identify predictive biomarkers, and overcome potential resistance mechanisms. With ongoing advancements in immunotherapy, the future holds great potential for transforming the landscape of oral tumor treatment and providing new hope for patients.

Therapeutic Role of Synthetic Lethality in ARID1A-Deficient Malignancies.

AT-rich interaction domain 1A (ARID1A), a mammalian switch/sucrose nonfermenting complex subunit, modulates several cellular processes by regulating chromatin accessibility. It is encoded by ARID1A, an immunosuppressive gene frequently disrupted in a many tumors, affecting the proliferation, migration, and invasion of cancer cells. Targeting molecular pathways and epigenetic regulation associated with ARID1A loss, such as inhibiting the PI3K/AKT pathway or modulating Wnt/β-catenin signaling, may help suppress tumor growth and progression. Developing epigenetic drugs like histone deacetylase or DNA methyltransferase inhibitors could restore normal chromatin structure and function in cells with ARID1A loss. As ARID1A deficiency correlates with enhanced tumor mutability, microsatellite instability, high tumor mutation burden, increased programmed death-ligand 1 expression, and T-lymphocyte infiltration, ARID1A-deficient cells can be a potential therapeutic target for immune checkpoint inhibitors that warrants further exploration. In this review, we discuss the role of ARID1A in carcinogenesis, its crosstalk with other signaling pathways, and strategies to make ARID1A-deficient cells a potential therapeutic target for patients with cancer.

Inhibition of PTPN3 Expressed in Activated Lymphocytes Enhances the Antitumor Effects of Anti-PD-1 Therapy in Head and Neck Cancer, Especially in Hypoxic Environments.

In the tumor microenvironment, wherein cytotoxic lymphocytes interact with cancer cells, lymphocyte exhaustion, an immune checkpoint inhibitor target, is promoted. However, the efficacy of these inhibitors is limited, and improving response rates remains challenging. We previously reported that protein tyrosine phosphatase nonreceptor type (PTPN) 3 is a potential immune checkpoint molecule for activated lymphocytes and that PTPN3 inhibition should be a focus area for cancer immunotherapy development. Therefore, in this study, we focused on PTPN3-suppressive therapy in terms of lymphocyte exhaustion under hypoxic conditions, which are a cancer microenvironment, and investigated measures for improving the response to anti-programmed death receptor (PD)-1 antibody drugs. We found that PTPN3 expression was upregulated in activated lymphocytes under hypoxic conditions, similar to the findings for other immune checkpoint molecules, such as PD-1, T cell immunoglobulin mucin-3, and lymphocyte-activation gene-3; furthermore, it functioned as a lymphocyte exhaustion marker. In addition, PTPN3-suppressed activated lymphocytes promoted the mammalian target of rapamycin (mTOR)-Akt signaling pathway activation and enhanced proliferation, migration, and cytotoxic activities under hypoxic conditions. Furthermore, PTPN3 suppression in activated lymphocytes increased PD-1 expression and enhanced the antitumor effects of anti-PD-1 antibody drugs against head and neck cancer in vitro and in vivo. These results suggest that the suppression of PTPN3 expression in activated lymphocytes enhances the therapeutic effect of anti-PD-1 antibody drugs in head and neck cancer, especially under hypoxic conditions that cause lymphocyte exhaustion.

Clinical Significance of Tumor Immune Microenvironment in Endometrial Endometrioid Carcinoma, Grade 1 With DNA Mismatch Repair Protein Loss.

The administration of immune checkpoint inhibitors (ICIs) is increasing in endometrial cancer, especially in the mismatch repair (MMR)-deficient group. To prevent unnecessary immune-related adverse events, ICIs need to be administered to more appropriate patients. The tumor immune microenvironment has been reported to be a predictive marker of the efficacy of ICI therapies. This study evaluated CD8, FoxP3, CD68, PD-L1, and β-catenin expression in endometrial endometrioid carcinoma, grade 1 (G1) with DNA mismatch repair protein loss (MMR loss), and their association with clinicopathological features. We retrospectively analyzed tumor samples from 107 patients with endometrial endometrioid carcinoma, G1 (MMR-deficient group: n=67; MMR-proficient group: n=40). Overall, 47 cases of MLH1/PMS2 loss and 20 cases of MSH2/MSH6 loss were observed. The patients with low intraepithelial CD8 expression significantly more frequently exhibited deep myometrial invasion, and the elderly group (≥60 y) significantly more frequently showed low stromal CD8 expression. In addition, FoxP3-positive cell count and FoxP3/CD8+ ratio were significantly correlated with the International Federation of Obstetrics and Gynecology 2023 stage and lymph node metastasis. In the Kaplan-Meier analysis, the patients with low intraepithelial or stromal CD8 expression had shorter progression-free survival (PFS) than those with high intraepithelial or stromal CD8 expression, albeit not significantly. We clarified that the tumor immune microenvironment had an impact on clinicopathological features within the group with MMR loss, which is the main target for ICIs, limited to endometrioid carcinoma, G1. Further studies are needed, including on patients administered ICIs.

Immune-related adverse events in patients with gastrointestinal cancer undergoing pembrolizumab monotherapy: A systematic review of clinical trials.

744 Background: Pembrolizumab, an immune checkpoint inhibitor targeting programmed death 1 (PD-1), is widely employed in the treatment of various gastrointestinal (GI) cancers. This systematic review aims to assess the spectrum and incidence of immune-related adverse events (irAEs) associated with pembrolizumab monotherapy in GI cancer patients. Methods: A comprehensive search of PubMed/MEDLINE was conducted to identify full-text articles of clinical trials investigating pembrolizumab monotherapy in GI cancer patients. Two independent authors reviewed the articles and extracted data, with discrepancies resolved by consensus. Primary endpoints included the incidence of grade 3 or higher irAEs and the treatment discontinuation rate due to irAEs. Secondary endpoints encompassed the incidence of any-grade irAEs and specific irAEs such as pneumonitis, colitis, hepatitis, myositis, myocarditis, nephritis, pancreatitis, peripheral neuropathy, skin toxicity, endocrine toxicity, infusion reactions, and deaths. Results: After excluding duplicates and articles not meeting inclusion criteria, data extraction and analysis were performed on 25 selected articles. Common reasons for exclusion included concomitant use of chemotherapy or targeted therapy and trials involving non-GI cancer patients. The analysis included 2866 patients with a median age of 62 years, of which 29% were female. Tumor types included colorectal (13%), esophagogastric (46%), hepatocellular carcinoma (25%), and others (16%). The aggregate incidence of grade 3 or higher irAEs was 8.7%, with reported rates ranging from 3% to 41% across different trials. The incidence of any grade irAEs varied from 39% to 98%. The treatment discontinuation rate due to irAEs was 6.8%. The most common grade 3 or higher irAEs were hepatitis (3.6%), pneumonitis (0.8%), and colitis (0.7%). irAE-related deaths were infrequent (0.9%). Detailed irAE data are summarized in the Table. Conclusions: In GI cancer patients receiving pembrolizumab monotherapy, severe irAEs are rare. Treatment discontinuation and deaths attributed to pembrolizumab-related irAEs are infrequent, underscoring the safety profile of this therapy in patients with GI cancer. [Table: see text]

Mitochondrial DNA copy number plays opposing roles in T-lymphocyte infiltration of colorectal cancer based on mismatch repair status: new directions for immunotherapy?

Researchers have previously reported that mitochondrial DNA copy number (mtDNA-CN) can play different roles in microsatellite instable/mismatch repair-deficient (MSI/dMMR) and microsatellite stable/mismatch repair-proficient (MSS/pMMR) colorectal cancer (CRC). To support malignancy, dMMR CRC relies on glycolysis, while pMMR CRC favors oxidative phosphorylation. However, it is unclear whether mtDNA-CN changes are related to T cell infiltration in CRC. The mtDNA-CN was detected by qRT-PCR in 532 patients, and the expression of CD3 and CD8 in 485 patients was detected by immunohistochemistry. The correlation between mtDNA-CN and the prognosis of CRC patients was further analyzed, and the correlation between mtDNA-CN and T lymphocyte infiltration was also analyzed. Biopsy specimens from the immune checkpoint inhibitors (ICIs) treatment cohort were obtained to verify the correlation between mtDNA-CN and the efficacy of ICIs. The effects of mtDNA-CN and MMR status on gene expression were analyzed by RNA-seq. Our results show that mtDNA-CN has inverse relationships to CRC prognosis in cases with different MMR statuses, potentially inducing the U-shaped association in CRC. The opposing correlations between mtDNA-CN and T lymphocyte infiltration in cases of dMMR CRC and pMMR CRC further suggest that mtDNA-CN might play an important role in CRC development. More importantly, cases of pMMR CRC with lower mtDNA-CN and of dMMR CRC with higher mtDNA-CN can benefit more dramatically from ICIs. Furthermore, RNA-seq revealed a link between the level of mtDNA-CN and T lymphocyte infiltration in CRC cases with different MMR statuses. Our study found a potential relationship between mtDNA-CN and CRC development that differs by MMR status, potentially providing a rationale for the use of mtDNA-CN as both a predictive biomarker and a therapeutic target for ICIs.

Immunohistochemical study of Programmed Cell Death Ligand 1 (PDL1) expression by combined positive score using 22C3 clone in head and neck squamous cell carcinomas, its correlation with clinicopathological features and outcome.

Programmed cell death ligand 1 (PD L1) is a transmembrane protein that is highly expressed in neoplastic cells. Therapy with immune checkpoint inhibitors target PD-1/PD-L1 blockade-inducing tumour regression. Immunohistochemistry (IHC) for PD-L1 expression enables patient selection for immunotherapy and can be considered as a potential predictive biomarker for immunotherapy in head and neck squamous cell carcinoma (HNSCC). To determine the PDL1 expression in HNSCC, to correlate with clinicopathological features and outcome. We retrospectively analysed 59 cases of HNSCC at our Tertiary Hospital between January 2017 and November 2018 and followed up until death/Nov 2022 for Overall survival. IHC analysis of PD-L1 using Combined Positive Score (CPS) with antibody clone 22C3 in 59 cases of HNSCC was performed. PD-L1 expression was correlated with clinicopathological features and outcomes. Pearson Chi-square test was used to analyse the correlation between PD-L1 expression and clinicopathological parameters using SPSS20.0. Survival curves were calculated by Kaplan-Meier method, and differences were analysed by log-rank test. A total of 25 cases (42.4%) had positive PDL expression (CPS ≥1). 16/25 cases (27.1%) belonged to CPS (≥1, <10). An almost-perfect interobserver agreement was noted by two pathologists for PD-L1 IHC expression. No statistically significant correlation was noted between PD-L1 score and clinicopathologic features. Detection of PD-L1 status gives further insight into frequency of PD-L1 expression in Indian HNSCC patients to possibly improve clinical treatment strategies, ensuring that our patients get the maximum therapeutic benefit of immunotherapy.

LAG3 is an independent prognostic biomarker and potential target for immune checkpoint inhibitors in malignant pleural mesothelioma: a retrospective study

BackgroundLymphocyte-activation gene 3 (LAG3) is an immune checkpoint receptor; novel LAG3 immune checkpoint inhibitors (ICIs) exhibit therapeutic activity in melanoma. The role of LAG3and ICIs of LAG3 are unknown in malignant pleural mesothelioma (MPM). This study aimed to uncover the prognostic landscape of LAG3 in multiple cancers and investigate the potential of using LAG3 as an ICIs target in patients with MPM.MethodsWe used The Cancer Genome Atlas (TCGA) cohort for assessing mRNA expression and our cohort for immunohistochemical expression. TCGA cohort were analyzed using the Wilcoxon rank-sum test to compare mRNA expression between normal and tumor tissues in multiple cancers. We used 86 MPM cases from TCGA and 38 MPM cases from our cohort to analyze the expression of LAG3 in tumor-infiltrating lymphocytes. The mean LAG3 mRNA expression was set as the cut-off and samples were classified as positive/negative for immunohistochemical expression. Overall survival (OS) of patients with MPM was determined using the Kaplan–Meier method based on LAG3 mRNA and immunohistochemical expression. OS analysis was performed using the multivariate Cox proportional hazards model. The correlation of LAG3 expression and mRNA expression of tumor immune infiltration cells (TIICs) gene markers were estimated using Spearman correlation. To identify factors affecting the correlation of LAG3 mRNA expression, a multivariate linear regression model was performed.ResultsLAG3 mRNA was associated with prognosis in multiple cancers. Elevated LAG3 mRNA expression was correlated with a better prognosis in MPM. LAG3 expression was detected immunohistochemically in the membrane of infiltrating lymphocytes in MPM. LAG3 immunohistochemical expression was correlated with a better prognosis in MPM. The multivariate Cox proportional hazards model revealed that elevated LAG3 immunohistochemical expression indicated a better prognosis. In addition, LAG3 mRNA expression was correlated with the expression of various gene markers of TIICs, the most relevant to programmed cell death 1 (PD-1) with the multivariate linear regression model in MPM.ConclusionsLAG3 expression was correlated with prognosis in multiple cancers, particularly MPM; LAG3 is an independent prognostic biomarker of MPM. LAG3 regulates cancer immunity and is a potential target for ICIs therapy. PD-1 and LAG3 inhibitors may contribute to a better prognosis in MPM.Trial registrationThis study was registered with UMIN000049240 (registration day: August 19, 2022) and approved by the Institutional Review Board (approval date: August 22, 2022; approval number: 2022–0048) at Tokyo Women’s Medical University.

Abstract A035: Comparing the clinical and genomic landscapes of acral, mucosal, and cutaneous metastatic melanomas treated with immune checkpoint inhibitors

Abstract Background: Melanoma is a melanocytic malignancy that is classified into different subtypes, including cutaneous (CM), acral (AM), and mucosal melanoma (MM). Immune checkpoint inhibitors (ICI) targeting PD-1 and/or CTLA-4 have emerged as the standard of care for advanced metastatic melanoma. We investigated responses to ICIs, genomic profiles, and molecular differences among these different subtypes of melanoma. Methods: We performed a multi-center retrospective cohort study including patients with metastatic melanoma who received anti-PD1 +/- CTLA4 inhibitor ICI for metastatic disease. We employed the AACR GENIE (v13.1) cancer database, DepMap portal, and Enrichr web tool with MSigDB Hallmark 2020 database to analyze the incidence and distribution of significant alterations, differentially expressed genes, and pathway enrichment within distinct melanoma subtypes. Results: We identified 337 patients with advanced melanoma who received anti-PD1 +/- anti-CTLA4 for metastatic disease. CM was the most frequent melanoma subtype (81%), followed by MM (12%), and AM (8%). Patients with AM had the shortest OS and PFS CM (OS 3.4 years, PFS of 1.1 years), AM median (OS 1.4 years, PFS 3.8 months), and MM (OS 1.7 years, PFS 6 months; OS, P= 0.028; PFS P=0.029). Patients with CM or MM experienced longer OS with anti-PD1 +/- CTLA4 vs. anti-PD1 monotherapy, but no survival advantage was observed in patients with AM. In the GENIE dataset, we identified 2015/374/177 samples with CM/MM/AM, respectively. AM and MM patients were significantly more likely to be Female, Black or Asian than CM patients. BRAF V600 mutations were most frequent in CM (40%), followed by MM (7%) and AM (14%). However, MM and AM had an increase in alterations in cell cycle regulator genes. The incidence of CDK4 and CCND1 amplification, respectively was highest in AM (17%, 16%), followed by MM (6%, 6%) and CM (2%, 3%). We compared the pathways represented by differentially altered genes in AM vs. CM: G2M-Checkpoint (Q&amp;lt;0.05) and E2F targets (Q&amp;lt;0.05) pathways were enriched in AM. We also compared RNAseq data from n=4) AM and n=20 CM cell lines, and found the same pathways enriched amongst genes that were differentially expressed between AM and CM: G2M-Checkpoint (Q&amp;lt;0.01) and E2F targets (Q&amp;lt;0.01) Conclusions: Our findings highlight comparatively poor outcomes with ICIs in Acral Melanoma. AM has lower rates of actionable BRAF mutations; as such, very few patients with metastatic AM have access to effective 1st or 2nd line therapies. Thus, there is an urgent need to explore alternative therapeutic targets. Our data implicate cell cycle inhibitors as potentially important components of novel treatment strategies that could augment immunotherapy efficacy for patients with metastatic AM. Citation Format: Sadaf Solati, April A. N. Rose, Anna Spreafico, Adrian Sacher, Denis Yahiaoui, Wilson H. Miller. Comparing the clinical and genomic landscapes of acral, mucosal, and cutaneous metastatic melanomas treated with immune checkpoint inhibitors [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A035.