Immuno-oncology Agents Research Articles

Abstract B015: Tumor fraction as a predictive factor of outcome of patients referred for oncology early phase clinical trials: Analysis of the STING precision medicine study

Abstract Background The quantification of ctDNA shed by measuring tumor fraction (TF) has been associated with prognosis in solid tumors pts. However, whether TF can be also predictive of clinical benefit of systemic treatments in patients referred for early phase studies remain unknown. Methods: All consecutive adult pts with an advanced solid tumor referred to the Early Phase Trials Department of Gustave Roussy( Villejuif France) between December 2020 and December 2021 and enrolled in the precision medicine study STING (NCT04932525, sponsor: Institut Gustave Roussy, Villejuif, France) were analyzed. All pts underwent comprehensive genomic profiling with the 324-gene FoundationOne. TF was analyzed as a binary variable, indicating whether a specimen had TF ≥10% or TF <10%. Response to treatment was assessed as per RECIST criteria. Multivariate analysis included previously validated prognostic scores: the Royal Marsden Hospital (albumin, LDH, number of metastatic sites) and the GRIm (LDH, neutrophil/lymphocyte ratio (NLR), albumin) scores as well as their individual components. Results: 947 patients entered the study. High TF was associated with significantly worse overall survival (OS) (HR:2.52 [CI95%: 2.06 - 3.08, p<0.001] independently of the RMH and GRIM scores as well as their individual components. 409 pts received a systemic treatment following ctDNA profiling (Immuno-oncology agent: 146 patients, non-IO: 254 patients)The treatment was investigational for 200 patients. The most frequent tumor types were non-small cell lung cancer (n=85), prostate cancer (n=49), colorectal cancer (n=33). High TF was significantly associated with worse objective response/stable disease rate (37.8% vs 53.8%, p=0.006), PFS (2.1 vs 3.9 months, p<0.001) and OS (7.1 vs 18.6 months, p<0.001) . Conclusions: Besides its prognostic value, TF is predictive of outcome on systemic therapy in patients referred for early phase studies. This parameter can be used for informed decision making for patients before participating in phase 1 trials. Citation Format: Laila Belcaid, Arnaud Bayle, Kilian Trin, Mihaela Aldea, Damien Vasseur, Madona Sakkal, Yohann Loriot, Antoine Hollebecque, Santiago Ponce, Antoine Italiano. Tumor fraction as a predictive factor of outcome of patients referred for oncology early phase clinical trials: Analysis of the STING precision medicine study [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B015.

Uptake and efficacy of immuno-oncology combinations in metastatic renal cell carcinoma in the United States: Evidence from the ASCO CancerLinQ Discovery database.

532 Background: Immuno-Oncology (IO) combinations, either an IO/IO (ipilimumab/nivolumab) or an IO/TKI combination (pembrolizumab/axitinib, avelumab/axitinib, nivolumab/cabozantinib, and pembrolizumab/lenvatinib), have emerged as the standard of care for frontline treatment of metastatic clear cell renal cell carcinoma (mccRCC) since 2018. Here we present uptake trends and efficacy of IO combinations in the United States from 2018 to 2022 using American Society of Clinical Oncology’s (ASCO) CancerLinQ Discovery database (CLQD). Methods: Patients diagnosed with mccRCC treated with frontline IO-based combinations from 2018-2022 were identified in the CLQD kidney dataset. The Kaplan-Meier survival method was used to present time to treatment discontinuation (TTD) and overall survival (OS) stratified by International mRCC Database Consortium (IMDC) risk. Results: There were 515 mccRCC patients who received frontline IO agents in 2018-2022: 228 (44.3%) patients received ipilimumab/nivolumab, 153 (29.7%) patients received IO/TKI (139 out of 153 received pembrolizumab/axitinib), and 122 (23.7%) patients received IO monotherapy (nivolumab or pembrolizumab). 385 (75%) were IMDC intermediate/poor risk and 97 (19%) were favorable risk patients. The median age was 69 (interquartile range: 61-79) and 59% were male. There was an increasing trend of use of IO/TKI from 2019 to 2021 [30.8%, 42.8%, 44.3%, respectively; analysis for 2022 was limited by sample size (n = 8)]. The median follow-up for ipilimumab/nivolumab and pembrolizumab/axitinib was 13.1 and 11.8 months (mos), respectively. The mTTD for ipilimumab/nivolumab and pembrolizumab/axitinib was 8.5 vs 11.0 mos, respectively. The median OS (mOS) was not reached (NR) in either regimen. The TTD and OS stratified by IMDC risk are presented in Table 1. Conclusions: Uptake of frontline IO combinations therapy in mccRCC and in particular IO/TKI combinations increased in the United States since 2018. Compared to progression-free survival (PFS) from the landmark trials, this analysis demonstrated shorter TTD, indicating either underestimation of the true PFS or worse outcomes in a non-clinical trial setting. Integration of radiologic response into this dataset could help clarify outcomes.[Table: see text]

Integrating [18F]-Fluorodeoxyglucose Positron Emission Tomography with Computed Tomography with Radiation Therapy and Immunomodulation in Precision Therapy for Solid Tumors.

[18F]-FDG positron emission tomography with computed tomography (PET/CT) imaging is widely used to enhance the quality of care in patients diagnosed with cancer. Furthermore, it holds the potential to offer insight into the synergic effect of combining radiation therapy (RT) with immuno-oncological (IO) agents. This is achieved by evaluating treatment responses both at the RT and distant tumor sites, thereby encompassing the phenomenon known as the abscopal effect. In this context, PET/CT can play an important role in establishing timelines for RT/IO administration and monitoring responses, including novel patterns such as hyperprogression, oligoprogression, and pseudoprogression, as well as immune-related adverse events. In this commentary, we explore the incremental value of PET/CT to enhance the combination of RT with IO in precision therapy for solid tumors, by offering supplementary insights to recently released joint guidelines.

Clinico-Pathological Features Influencing the Prognostic Role of Body Mass Index in Patients With Advanced Renal Cell Carcinoma Treated by Immuno-Oncology Combinations (ARON-1).

Obesity has been associated with improved response to immunotherapy in cancer patients. We investigated the role of body mass index (BMI) in patients from the ARON-1 study (NCT05287464) treated by dual immuno-oncology agents (IO+IO) or a combination of immuno-oncology drug and a tyrosine kinase inhibitors (TKI) as first-line therapy for metastatic renal cell carcinoma (mRCC). Medical records of patients with documented mRCC treated by immuno-oncology combinations were reviewed at 47 institutions from 16 countries. Patients were assessed for overall survival (OS), progression-free survival (OS), and overall clinical benefit (OCB), defined as the sum of the rate of partial/complete responses and stable disease. Univariate and multivariate analyses were used to explore the association of variables of interest with survival. A total of 675 patients were included; BMI was >25 kg/m2 in 345 patients (51%) and was associated with improved OS (55.7 vs. 28.4 months, P < .001). The OCB of patients with BMI >25 kg/m2 versus those with BMI ≤25 kg/m2 was significantly higher only in patients with nonclear cell histology (81% vs. 65%, P = .011), and patients with liver metastases (76% vs. 58%, P = .007), Neutrophil to lymphocyte ratio >4 (77% vs 62%, P = .022) or treated by nivolumab plus ipilimumab (77% vs. 64%, P=.044). In the BMI ≤25 kg/m2 subgroup, significant differences were found between patients with NLR >4 versus ≤4 (62% vs. 82%, P = .002) and patients treated by IO+IO versus IO+TKIs combinations (64% vs. 83%, P = .002). Our study suggests that the prognostic significance and the association of BMI with treatment outcome varies across clinico-pathological mRCC subgroups.

Comprehensive immunophenotyping of solid tumor-infiltrating immune cells reveals the expression characteristics of LAG-3 and its ligands.

Immune cell expression profiling from patient samples is critical for the successful development of immuno-oncology agents and is useful to understand mechanism-of-action, to identify exploratory biomarkers predictive of response, and to guide treatment selection and combination therapy strategies. LAG-3 is an inhibitory immune checkpoint that can suppress antitumor T-cell responses and targeting LAG-3, in combination with PD-1, is a rational approach to enhance antitumor immunity that has recently demonstrated clinical success. Here, we sought to identify human immune cell subsets that express LAG-3 and its ligands, to characterize the marker expression profile of these subsets, and to investigate the potential relationship between LAG-3 expressing subsets and clinical outcomes to immuno-oncology therapies. Comprehensive high-parameter immunophenotyping was performed using mass and flow cytometry of tumor-infiltrating lymphocytes (TILs) and peripheral blood mononuclear cells (PBMCs) from two independent cohorts of samples from patients with various solid tumor types. Profiling of circulating immune cells by single cell RNA-seq was conducted on samples from a clinical trial cohort of melanoma patients treated with immunotherapy. LAG-3 was most highly expressed by subsets of tumor-infiltrating CD8 T central memory (TCM) and effector memory (TEM) cells and was frequently co-expressed with PD-1. We determined that these PD-1+ LAG-3+ CD8 memory T cells exhibited a unique marker profile, with greater expression of activation (CD69, HLA-DR), inhibitory (TIM-3, TIGIT, CTLA-4) and stimulatory (4-1BB, ICOS) markers compared to cells that expressed only PD-1 or LAG-3, or that were negative for both checkpoints. In contrast to tumors, LAG-3 expression was more limited in circulating immune cells from healthy donors and solid tumor patients. Additionally, we found abundant expression of the LAG-3 ligands MHC-II and galectin-3 in diverse immune cell types, whereas FGL1 and LSECtin were minimally expressed by immune cells in the tumor microenvironment (TME). Lastly, we found an inverse relationship between baseline and on-treatment levels of circulating LAG3 transcript-expressing CD8 memory T cells and response to combination PD-1 and CTLA-4 blockade in a clinical trial cohort of melanoma patients profiled by scRNAseq. These results provide insights into the nature of LAG-3- and ligand-expressing immune cells within the TME, and suggest a biological basis for informing mechanistic hypotheses, treatment selection strategies, and combination immunotherapy approaches to support continued development of dual PD-1 and LAG-3 blockade.

MicroRNAs as Potential Regulators of GSK-3β in Renal Cell Carcinoma.

The prognosis of patients with advanced renal cell carcinoma (RCC) has improved with newer therapies, including molecular-targeted therapies and immuno-oncology agents. Despite these therapeutic advances, many patients with metastatic disease remain uncured. Inhibition of glycogen synthase kinase-3β (GSK-3β) is a promising new therapeutic strategy for RCC; however, the precise regulatory mechanism has not yet been fully elucidated. MicroRNAs (miRNAs) act as post-translational regulators of target genes, and we investigated the potential regulation of miRNAs on GSK-3β in RCC. We selected nine candidate miRNAs from three databases that could potentially regulate GSK-3β. Among these, hsa-miR-4465 (miR-4465) was downregulated in RCC cell lines and renal cancer tissues. Furthermore, luciferase assays revealed that miR-4465 directly interacted with the 3' untranslated region of GSK-3β, and Western blot analysis showed that overexpression of miR-4465 significantly decreased GSK-3β protein expression. Functional assays showed that miR-4465 overexpression significantly suppressed cell invasion of A498 and Caki-1 cells; however, cell proliferation and migration were suppressed only in Caki-1 and A498 cells, respectively, with no effect on cell cycle and apoptosis. In conclusion, miR-4465 regulates GSK-3β expression but does not consistently affect RCC cell function as a single molecule. Further comprehensive investigation of regulatory networks is required in this field.

Managing the Risk of Lung Toxicity with Trastuzumab Deruxtecan (T-DXd): A Canadian Perspective.

Ongoing advances in precision cancer therapy have increased the number of molecularly targeted and immuno-oncology agents for a variety of cancers, many of which have been associated with a risk of pulmonary complications, among the most concerning being drug-induced interstitial lung disease/pneumonitis (DI-ILD). As the number of patients undergoing treatment with novel anticancer agents continues to grow, DI-ILD is expected to become an increasingly significant clinical challenge. Trastuzumab deruxtecan (T-DXd) is an antibody-drug conjugate targeting human epidermal growth factor receptor 2 that is gaining widespread use in the metastatic breast cancer setting and is undergoing exploration for other oncologic indications. ILD/pneumonitis is an adverse event of special interest associated with T-DXd, which has potentially fatal consequences if left untreated and allowed to progress. When identified in the asymptomatic stage (grade 1), T-DXd-related ILD can be monitored and treated effectively with the possibility of treatment continuation. Delayed diagnosis and/or treatment, however, results in progression to grade 2 or higher toxicity and necessitates immediate and permanent discontinuation of this active agent. Strategies are, therefore, needed to optimize careful monitoring during treatment to ensure patient safety and optimize outcomes. Several guidance documents have been developed regarding strategies for the early identification and management of T-DXd-related ILD, although none have been within the context of the Canadian health care environment. A Canadian multidisciplinary steering committee was, therefore, convened to evaluate existing recommendations and adapt them for application in Canada. A multidisciplinary approach involving collaboration among medical oncologists, radiologists, respirologists, and allied health care professionals is needed to ensure the proactive identification and management of T-DXd-related ILD and DI-ILD associated with other agents with a similar toxicity profile.

Considerations for the clinical development of immuno-oncology agents in cancer.

Targeting of the immune system has shown to be a successful therapeutic approach in cancer, with the development of check point inhibitors (ICI) or T-cell engagers (TCE). As immuno-oncology agents modulate the immune system to attack cancer cells and do not act directly on oncogenic vulnerabilities, specific characteristics of these compounds should be taken in consideration during clinical development. In this review we will discuss relevant concepts including limitations of preclinical models, special pharmacologic boundaries, clinical development strategies such as the selection of clinical indication, line of treatment and backbone partner, as well as the endpoints and expected magnitude of benefit required at different stages of the drug development. In addition, future directions for early and late trial designs will be reviewed. Examples from approved drugs or those currently in clinical development will be discussed and options to overcome these limitations will be provided.

Current Trends in Immuno-Oncology.

Surgery, radiation, chemotherapy, and targeted therapy were the four basic kinds of cancer treatment until recently. Immuno-oncology (IO), or the concept that cancer cells were damaged by activating the body's immune system, has emerged and is explained as a unique and crucial method for treating different cancers over the last decade. The US Food and Drug Administration and the European Medicines Agency both approved this newly recognized way of treating cancer in 2020. Within IO, different therapeutic classes have arisen, which are the subject of this article. Immune checkpoint inhibitors are currently the most well-known therapeutic class of immuno-oncology medications due to their amazing ability to show efficacy in a variety of tumor types. Biomarkers were tested for different tumors like gastrointestinal cancer, whole Head, lower and upper part Neck cancer, and also cervical cancer by programmed death-ligand 1 (PD-L1) check point and their targets and are currently being utilized prior to treatment by using Pembrolizumab. However, the significance of PD-L1 expression for immune check point reticence therapy in other/different onco-cancer types remains unclear. Homogenized immuneoncology drugs with regular therapy have been recently studied and clinical efficacy outcomes have shown to be significantly improved. While IO agents are fast transforming the marketed treatment for cancer patients, there are still a number of obstacles to overcome in terms of associating their adverse effects and confirming those different healthcare systems, such as financing these expensive therapies. In addition to cancer vaccines and chimeric antigen receptor T-cell treatments, other IO drugs are in pipeline containing chimeric antigen receptor T-cell therapies; earlier ones have their own set of toxicities and high cost related challenges.

Exploiting an Interleukin-15 Heterodimeric Agonist (N803) for Effective Immunotherapy of Solid Malignancies.

Identifying effective immunotherapies for solid tumors remains challenging despite the significant clinical responses observed in subsets of patients treated with immune checkpoint inhibitors. Interleukin-15 (IL-15) is a promising cytokine for the treatment of cancer as it stimulates NK and CD8+ lymphocytes. However, unfavorable pharmacokinetics and safety concerns render recombinant IL-15 (rIL-15) a less attractive modality. These shortcomings were addressed by the clinical development of heterodimeric IL-15 agonists, including N803. In preclinical tumor models, N803 elicited significant Th1 immune activation and tumor suppressive effects, primarily mediated by NK and CD8+ T lymphocytes. In addition, multiple clinical studies have demonstrated N803 to be safe for the treatment of cancer patients. The combination of N803 with the immune checkpoint inhibitor nivolumab demonstrated encouraging clinical responses in nivolumab-naïve and nivolumab-refractory patients with non-small cell lung cancer. In a recent Phase II/III clinical study, most Bacillus Calmette-Guerin (BCG)-refractory bladder cancer patients treated with N803 plus BCG experienced durable complete responses. Currently, N803 is being evaluated preclinically and clinically in combination with various agents, including chemotherapeutics, immune checkpoint inhibitors, vaccines, and other immuno-oncology agents. This report will review the mechanism(s) of action of N803 and how it relates to the preclinical and clinical studies of N803.

Data from the 2022 ASCO Annual Meeting on surgical therapy

Last year, studies on immuno-oncologic treatment approaches for recurrent or metastatic head and neck cancer were the main focus at the two major international cancer congresses of the American Society of Clinical Oncology (ASCO) and the European Society for Medical Oncology (ESMO). The success of these therapeutic strategies has led to many new studies, including their use in the neoadjuvant setting. This review article summarizes presented studies from ASCO 2022 in which surgical therapy is the focus of the study protocol and also includes study results on neoadjuvant treatment strategies. No surgical trials were presented at ESMO 2022. At ASCO 2022 as well as in previous years, it became increasingly clear that treatment de-escalation in the context of human papillomavirus (HPV)-associated oropharyngeal carcinoma treatment involving surgical measures appears to be oncologically safe and functionally beneficial. In addition, anumber of studies indicate that in the setting of neoadjuvant administration of immuno-oncologic agents, aproportion of patients have pathologic complete remission. In this fraction of patients, which is usually significantly smaller than 50%, survival data are better than in those who have already failed to respond to neoadjuvant therapy. Unfortunately, however, significant toxicities or tumor progression with the risk of inoperability were also seen under these current therapeutic regimens, leading to discontinuation of therapy in 5-20% of cases. It remains to be seen whether neoadjuvancy with immune checkpoint inhibitors can establish itself, in contrast to the failed attempts of the past with the use of cytostatics.

Prognostic factors of early mortality in children and adolescents enrolled in oncology trials with a dose-finding part in the era of targeted and immune therapies: An Innovative Therapies for Children with Cancer (ITCC) study.

10020 Background: Phase I/II trials play a key role for children with relapsed/refractory tumors. Life expectancy beyond 8-12 weeks is a common eligibility criterion. However, there are no objective means to determine life expectancy for trial candidates. A better understanding of the risk factors associated with early mortality on trial could maximize the efficiency of such trials, whilst ensuring the ethical aspects of recruitment. Methods: Patients with relapsed/refractory solid tumors or lymphomas aged &lt; 18 years and participating in interventional clinical trials with a dose-finding part between 2000-2018 in 14 ITCC centers (across 5 European countries) were eligible. The mortality at 30 and 90 days (30-DM and 90-DM, respectively) from Cycle1-Day1 (C1D1) and its association with clinical, laboratory and efficacy data were assessed. Validated prognostic scores (RMH, MDACC) were correlated with early mortality rates. Results: Overall, 527 cases were included in the study; 19 subjects had participated in &gt; 1 trial, leaving a total of 507 subjects enrolled in their first phase I/II trial. Median age at C1D1 was 11.6 years (range, 0.5-17.9); male:female ratio 1.2:1; central nervous system (CNS) tumors (40%) Vs extra-CNS tumors (60%); 75% cases were treated in trials with at least one targeted therapy. The 30-DM (24/507) and 90-DM (116/507) were 4.7% (95%CI 3.1-7.0) and 23.0% (95%CI 19.3-26.8), respectively. At baseline the clinical variables which correlated with higher 90-DM in the univariate analysis were: performance status (Lansky or Karnofsky) ≤80%, no school/work attendance, requirement of opioids, ≥3 metastatic sites, Hb &lt; 100 g/dL and Total Bilirubin, LDH or AST above normal levels (up to the maximum permitted according to protocol eligibility criteria). Higher RMH and MDACC scores also correlated with higher 90-DM. Conclusions: To our knowledge this is the largest case series of children and adolescents participating in pediatric phase I/II trials to date, in which most of the patients were treated with targeted or immuno-oncology agents. The reported 30-DM and 90-DM will serve as a reference benchmark for future trials. Performance status ≤80%, no school/work attendance, requirement of opioids and ≥3 metastatic sites correlated with higher 90-DM. Adult prognostic scores (RMH, MDACC) showed good correlation with 90-DM in the pediatric population. Prognostic factors of early mortality should be given appropriate relevance at the time of study design, informing families and recruiting patients to these studies.

Use of tumor mutational burden as a predictive marker of response to immuno-oncology agents: Initial experience at an academic center in Venezuela.

e14613 Background: Tumor Genetic Profiling (TGP) is steadily becoming the mainstay of clinical practice, namely, the Tumor Mutational Burden (TMB) is believed to be a predictor of efficacy to treatment with Immune Checkpoint Inhibitors (ICI). Recent studies have demonstrated that a high-TMB score (TMB-H) is associated with higher response rates. In Venezuela, the evidence of mutational frequencies obtained by TGP is limited, herein we present our experience at a large educational institution. Methods: In this retrospective cohort, we included 80 subjects with different types of solid tumors to whom TGP was performed to determine TMB values, as well as other associated mutations, between January 2020 and December 2022. In a subgroup of subjects in which ICI therapy was formally indicated (n=21) we used the Objective Response Rate (ORR) as a primary endpoint, recorded as the percentage of patients who had a complete response (CR) or partial response (PR), based on the RECIST v1.1 criteria. Treatment options included Ipilimumab, Atezolizumab, Pembrolizumab and Nivolumab, as either monotherapy or in combination according to the corresponding NCCN guidelines. A TMB-H score was defined as greater than 10 mutations per megabase. Results: A TMB-H was found in 11 samples, subjects with lung cancer accounted for the majority of this finding (n=6). The most frequently reported mutations were BRCA 1-2 (n=9), KRAS (n=9), and EGFR (n=4). In the subgroup treated with ICI, the ORR of the group with TMB-H was 71.42%, while in those with low TMB it was 35.71%. The differences in response rates, with a 95% CI, yielded a p=0.122; which corresponds to a statistically non-significant outcome. Conclusions: This study constitutes the first country-level documentation of what is becoming a standardized practice, and contributes to the growing evidence regarding the use of TMB-H as a marker to predict response to treatment. Our small cohort demonstrated a high ORR to ICI when a TMB-H score is present, albeit to a non-statistically significant degree. We will continue to follow-up these patients, as well as to include newly sequenced samples for TGP, to give greater statistical power to these findings.

Exploiting docetaxel-induced tumor cell necrosis with tumor targeted delivery of IL-12

There is strong evidence that chemotherapy can induce tumor necrosis which can be exploited for the targeted delivery of immuno-oncology agents into the tumor microenvironment (TME). We hypothesized that docetaxel, a chemotherapeutic agent that induces necrosis, in combination with the bifunctional molecule NHS-IL-12 (M9241), which delivers recombinant IL-12 through specific targeting of necrotic regions in the tumor, would provide a significant antitumor benefit in the poorly inflamed murine tumor model, EMT6 (breast), and in the moderately immune-infiltrated tumor model, MC38 (colorectal). Docetaxel, as monotherapy or in combination with NHS-IL-12, promoted tumor necrosis, leading to the improved accumulation and retention of NHS-IL-12 in the TME. Significant antitumor activity and prolonged survival were observed in cohorts receiving docetaxel and NHS-IL-12 combination therapy in both the MC38 and EMT6 murine models. The therapeutic effects were associated with increased tumor infiltrating lymphocytes and were dependent on CD8+ T cells. Transcriptomics of the TME of mice receiving the combination therapy revealed the upregulation of genes involving crosstalk between innate and adaptive immunity factors, as well as the downregulation of signatures of myeloid cells. In addition, docetaxel and NHS-IL-12 combination therapy effectively controlled tumor growth of PD-L1 wild-type and PD-L1 knockout MC38 in vivo, implying this combination could be applied in immune checkpoint refractory tumors, and/or tumors regardless of PD-L1 status. The data presented herein provide the rationale for the design of clinical studies employing this combination or similar combinations of agents.

Abstract LB316: A next-generation KRASG12C inhibitor ABSK071 demonstrated broad synergy with other therapeutic agents in KRASG12C mutated cancer models

Abstract Background: KRAS is frequently mutated in human cancers, including pancreatic (~90%), colorectal (~35%), and lung cancer (~25%). The KRASG12C mutation (single amino acid substitution of cysteine for glycine at position 12) accounts for ~14% of lung cancer, ~4% of colorectal cancer, and ~2% of pancreatic cancer. Currently, two covalent KRASG12C inhibitors, namely sotorasib (AMG-510) and adagrasib (MRTX-849), have been approved as monotherapy to treat locally advanced or metastatic NSCLC with KRASG12C mutation through accelerated approval process. Despite the beneficial effects of KRASG12C inhibitors in clinic for certain patients, the limited antitumor efficacy in most patients and potential drug resistance are major concerns. A next-generation inhibitor with better inhibitory activity may improve anti-tumor efficacy. Combination with other therapeutic agents may also improve the single-agent activity of KRASG12C inhibitors. These approaches could both overcome the limitations of sotorasib and adagrasib and provide additional benefits to patients. Materials and methods: KRASG12C inhibitory activity of ABSK071 was examined in vitro and in vivo in comparison with sotorasib and adagrasib. To identify potential targeted agents synergizing with ABSK071, we tested a set of inhibitors that targeting signaling components of KRAS pathways, including EGFRi, FGFRi, SHP2i and SOS1i, in combination with ABSK071 in cellular experiments using KRASG12C mutant cell lines. Cell growth inhibition was measured and synergistic effect was analyzed. In vivo efficacy study was also conducted to confirm the synergistic anti-tumor effect in animal models. A set of immuno-oncology reagents, including anti-PD-1/L1, CSF-1R inhibitor (ABSK021) and CD73 inhibitor (ABSK051) were also tested in combination with ABSK071 in vivo using mouse syngeneic models. Results: ABSK071 demonstrated much stronger inhibitory activity than sotorasib and adagrasib against a variety of cell lines harboring KRASG12C, as well as significantly better in vivo anti-tumor efficacy in xenograft models that were less sensitive to sotorasib. Synergistic effects on cell growth inhibition were observed in vitro with ABSK071 in combination with several agents including cetuximab, afatinib, AZD4547, TNO-155, RMC-4630 and BI3406. Superior anti-tumor activities were observed in vivo when these agents were combined with ABSK071 than in combination with sotorasib. In mouse syngeneic models harboring KrasG12C mutations, ABSK071 also demonstrated synergy with anti PD-1/L1 antibody or other IO reagents. Conclusions: ABSK071 is a next-generation KRASG12C inhibitor with greater activity and anti-tumor efficacy in vitro and in vivo. It also demonstrated broad synergistic effects with a large set of targeted agents and immuno-oncology agents, indicating its strong potential in combinatory therapy in treating a wider range of KRASG12C-dependent cancers. Citation Format: Haiyan Ying, Fushen Guo, Juan Peng, Jie Wang, Jie Zhang, Manqi Liu, Zhixuan Zhu, Zhui Chen. A next-generation KRASG12C inhibitor ABSK071 demonstrated broad synergy with other therapeutic agents in KRASG12C mutated cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB316.

A Novel Hydrogel-Based 3D In Vitro Tumor Panel of 30 PDX Models Incorporates Tumor, Stromal and Immune Cell Compartments of the TME for the Screening of Oncology and Immuno-Therapies.

Human-relevant systems that mimic the 3D tumor microenvironment (TME), particularly the complex mechanisms of immuno-modulation in the tumor stroma, in a reproducible and scalable format are of high interest for the drug discovery industry. Here, we describe a novel 3D in vitro tumor panel comprising 30 distinct PDX models covering a range of histotypes and molecular subtypes and cocultured with fibroblasts and PBMCs in planar (flat) extracellular matrix hydrogels to reflect the three compartments of the TME-tumor, stroma, and immune cells. The panel was constructed in a 96-well plate format and assayed tumor size, tumor killing, and T-cell infiltration using high-content image analysis after 4 days of treatment. We screened the panel first against the chemotherapy drug Cisplatin to demonstrate feasibility and robustness, and subsequently assayed immuno-oncology agents Solitomab (CD3/EpCAM bispecific T-cell engager) and the immune checkpoint inhibitors (ICIs) Atezolizumab (anti-PDL1), Nivolumab (anti-PD1) and Ipilimumab (anti-CTLA4). Solitomab displayed a strong response across many PDX models in terms of tumor reduction and killing, allowing for its subsequent use as a positive control for ICIs. Interestingly, Atezolizumab and Nivolumab demonstrated a mild response compared to Ipilimumab in a subset of models from the panel. We later determined that PBMC spatial proximity in the assay setup was important for the PD1 inhibitor, hypothesizing that both duration and concentration of antigen exposure may be critical. The described 30-model panel represents a significant advancement toward screening in vitro models of the tumor microenvironment that include tumor, fibroblast, and immune cell populations in an extracellular matrix hydrogel, with robust and standardized high content image analysis in a planar hydrogel. The platform is aimed at rapidly screening various combinations and novel agents and forming a critical conduit to the clinic, thus accelerating drug discovery for the next generation of therapeutics.

Abstract 818: Preclinical studies of the cabazitaxel nanoformulation MPB-1734 support therapeutic application in chemo-resistant solid tumors and synergistic benefit in combination with immune checkpoint inhibitor

Abstract Background: Cabazitaxel (CBZ) is a second-generation taxane that has the potential to overcome taxane-resistance due to the low affinity for the P-glycoprotein efflux pump. However, with the high systemic toxicity such as neutropenia and hypersensitivity, the clinical use is restricted to patients with metastatic castration-resistant prostate cancer who show progression after docetaxel-based chemotherapy. MPB-1734 is a CBZ nanoformulation which is currently being evaluated as monotherapy in patients with advanced solid tumors in a Phase 1/2a trial (NCT04643418). It is developed to overcome the limitations associated with CBZ application and as potential therapeutic agent for chemo-resistant cancers. This work outlines the results of preclinical studies that support the tumor targeting ability, improved safety profiles, significant therapeutic effect, and synergistic benefit in combination with immune checkpoint inhibitor. Methodology: A series of nonclinical studies of MPB-1734 were conducted including toxicology evaluations in two species and the antitumor activity evaluations in a range of xenograft mice models as cervical cancer (KB), ovarian cancer (OVCAR3) and platinum-resistant human ovarian cancer patient-derived-xenograft (PDX) model (OV0276). The antitumor activity of MPB1734 combined with anti-PD-1 antibody were also evaluated in the syngenetic 4T1 breast cancer mice model. Results: Toxicology evaluations of MPB-1734 demonstrated the safety profiles of CBZ were significantly improved, and the tolerated doses of MPB-1734 are at least 2 folds higher than commercial formulation. An in-vivo tumor targeting study showed that MPB1734 mainly accumulated in the tumor sites, rather than in the vital organs. MPB1734 exhibited a better efficacy compared to commercial formulation in KB and OVCAR3 models. For platinum-resistant PDX model, MPB-1734 demonstrated significant anti-tumor efficacy (TGI:100%, p&amp;lt;0.001). For 4T1 mice model, MPB-1734 combined with anti-PD-1 antibody demonstrated synergistic benefit (TGI: 78.6%) compared to anti-PD-1 antibody monotherapy (TGI: 2.8%) and MPB-1734 monotherapy (TGI: 52.9%). This synergistic benefit may result from increased CD8+ T cells in tumor region after MPB-1734 treatment. Conclusion: MPB-1734 can reduce the major dose-limiting side effect (neutropenia) of CBZ and increase the tolerated dose. With tumor targeting ability, superior antitumor effects were demonstrated as compared with commercial formulation in a range of cancer models. MPB-1734 combined with anti-PD-1 antibody showed synergistic benefit in tumor inhibition. These preclinical results support the potential use of MPB-1734 as therapeutic agent for chemo-resistant cancer with monotherapy or combination therapy with immuno-oncology agents. Citation Format: Yuan Hung Hsu, Chih-Lung Chen, Jhih-Yun Jian, Ming-Cheng Wei, Wen-Yuan Hsieh, Chia-Wen Huang, Yung-Chu Chen, Tzu-Hsin Liao, Shian-Jy Wang. Preclinical studies of the cabazitaxel nanoformulation MPB-1734 support therapeutic application in chemo-resistant solid tumors and synergistic benefit in combination with immune checkpoint inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 818.

Abstract 4155: The RAF/MEK clamp avutometinib (VS-6766) induces an immunogenic tumor microenvironment and potentiates the efficacy of anti-PD-1

Abstract The RAS/RAF/MEK/ERK (MAPK) pathway is one of the most commonly mutated oncogenic pathways in human cancers. Although RAS, RAF and MEK have been validated as anticancer targets with approval of KRAS G12C, BRAF and MEK inhibitors, combination strategies with chemotherapy, targeted therapies and/or immune checkpoint inhibitors may be optimal for deep and durable response. Avutometinib (avuto, VS-6766) is a unique RAF/MEK clamp that potently inhibits MEK kinase activity and induces a dominant negative RAF/MEK complex preventing phosphorylation of MEK by ARAF, BRAF and CRAF. Preclinically, avuto has shown strong anti-proliferative potency across tumor cell lines carrying various MAPK pathway alterations. Clinically, avuto monotherapy has shown responses in gynecological cancers and KRAS mutant non-small cell lung cancer. Here, we tested the immune modulatory effects of avuto on tumor cells and tumor-infiltrating immune cells and assessed anti-tumor efficacy in mice treated with avuto in combination with an anti-PD1 antibody. In a panel of KRAS and BRAF mutant human tumor cell lines, avuto treatment increased the expression of MHC-I complex genes, including B2M, HLA-A and TAP1. In the CT26 KRAS G12D syngeneic colorectal cancer model, upregulation of B2M and TAP1 by avuto was confirmed in vivo, suggesting that avuto may increase antigen presentation. Furthermore, avuto upregulated the expression of markers of T cells (CD8, PDCD1), NK cell activation (NCR1) and interferon response (IFNG, IRF7, IL12) in the CT26 model. Interestingly, all these pro-immune changes observed with avuto were stronger than those observed with an equivalent dose level of the MEK-only inhibitor trametinib. Avuto also increased expression of B2M, CD8A, PDCD1, NCR1 and IRF7 in a KPARG12C orthotopic lung cancer model. Flow cytometry analysis showed that avuto also significantly increased MHC-II expression by tumor cells and the numbers of CD8 T cells and M1 macrophages, and significantly decreased monocytic and granulocytic MDSCs. These immune changes indicate that avuto induces an immunogenic tumor microenvironment that may potentiate the efficacy of immuno-oncology agents such as anti-PD-1. Accordingly, in the CT26 model, whereas avuto and anti-PD-1 each delayed tumor growth, combination of avuto with anti-PD-1 increased antitumor efficacy and prolonged survival. Furthermore, all complete responders in the avuto + anti-PD-1 group were able to reject a re-challenge with CT26 tumor cells and showed increased CD8 and CD4 effector memory T cells relative to untreated naïve control mice, indicating that avuto + anti-PD-1 treatment induces durable immune memory. These results support clinical evaluation of avutometinib in combination with an anti-PD-1 antibody for treatment of patients with solid tumors harboring MAPK pathway alterations such as KRAS or BRAF mutations. Citation Format: Silvia Coma, Miriam Molina Arcas, Julian Downward, Jonathan A. Pachter. The RAF/MEK clamp avutometinib (VS-6766) induces an immunogenic tumor microenvironment and potentiates the efficacy of anti-PD-1. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4155.

Discovery of non-boronic acid Arginase 1 inhibitors through virtual screening and biophysical methods

Inhibiting Arginase 1 (ARG1), a metalloenzyme that hydrolyzes l-arginine in the urea cycle, has been demonstrated as a promising therapeutic avenue in immuno-oncology through the restoration of suppressed immune response in several types of cancers. Most of the currently reported small molecule inhibitors are boronic acid based. Herein, we report the discovery of non-boronic acid ARG1 inhibitors through virtual screening. Biophysical and biochemical methods were used to experimentally profile the hits while X-ray crystallography confirmed a class of trisubstituted pyrrolidine derivatives as optimizable alternatives for the development of novel classes of immuno-oncology agents targeting this enzyme.

Glioblastoma treatment slowly moves toward change: novel druggable targets and translational horizons in 2022

ABSTRACT Introduction Glioblastoma (GBM) is the most common primary brain tumor in adults. GBM treatment options have been the same for the past 30 years and have only modestly extended survival, despite aggressive multimodal treatments. The progressively better knowledge of GBM biology and a comprehensive analysis of its genomic profile have elucidated GBM heterogeneity, contributing to a more effective molecular classification and to the development of innovative targeted therapeutic approaches. Areas covered This article reports all the noteworthy innovations for immunotherapy and targeted therapy, providing insights into the current advances in trial designs, including combination therapies with immuno-oncology agents and target combinations. Expert opinion GBM molecular heterogeneity and brain anatomical characteristics critically restrain drug effectiveness. Nevertheless, stimulating insights for future research and drug development come from innovative treatment strategies for GBM, such as multi-specific ‘off-the-shelf’ CAR-T therapy, oncolytic viral therapy and autologous dendritic cell vaccination. Disappointing results from targeted therapies-clinical trials are mainly due to complex interferences between signaling pathways and biological processes leading to drug resistance: hence, it is imperative in the future to develop combinatorial approaches and multimodal therapies.