Tumor Growth Kinetics Research Articles

Velocity and pattern of growth of intracranial meningiomas.

The authors' aim was to assess the velocity and pattern of growth of meningiomas and to correlate the kinetics of tumor growth with their previously reported two-item radiological risk stratification and CNS WHO grade (5th edition, 2021). The authors performed a serial volumetric analysis of meningiomas diagnosed radiologically at their institution between 2003 and 2015. The primary endpoint was velocity of diametric expansion (VDE), which represents the slope of the linear regression of the mean tumor diameter against time. For the secondary analysis, they categorized the growth patterns as linear or exponential by fitting time-volume curves to a linear and exponential function. Three radiological risk categories based on T2-weighted iso/hyperintensity and absence of calcifications were compared: low risk (T2-weighted hypointense), intermediate-risk (T2-weighted iso/hyperintense with calcifications), and high-risk (T2-weighted iso/hyperintense without calcifications) tumors. For the entire cohort of 240 meningiomas, the median (IQR) VDE was 0.33 (0.00-0.71) mm/year. Distribution of VDE differed significantly among radiological risk categories (0.49 vs 0.35 vs 0.05 mm/year, p < 0.001). High-risk and intermediate-risk tumors more frequently tended to grow exponentially compared to low-risk tumors (43.8% vs 37.0% vs 8.3%, p = 0.067). The authors found no correlation of growth velocity with CNS WHO grade in their cohort (1.30 mm/year for CNS WHO grade 1 vs 4.01 mm/year for CNS WHO grade 2, p = 0.185). A radiological risk assessment using two parameters-T2-weighted signal iso/hyperintensity and absence of calcifications-allows estimation of growth velocity and characteristics of untreated intracranial meningiomas. Only high-risk tumors exhibit the potential for rapid growth. However, rapid tumor growth does not indicate a higher CNS WHO grade per se.

Значення пренатальної діагностики та диспансеризації в перинатальному супроводі плодів і новонароджених дітей із крижово-куприковими тератомами

Aim: to determine the importance of prenatal diagnosis in the perinatal care of fetuses and newborns with sacrococcygeal teratomas Materials and methods. A retrospective analysis of the medical cards of 26 newborns with sacrococcygeal teratomas (SCT) who underwent surgery in the period from 1983 to 2023. A statistical analysis of the value of prenatal diagnosis criteria in the perinatal care of fetuses and newborns with SCT was perfomed. P values less than 0.05 were considered reliable. Results. Prenatal SCT was diagnosed in 69.2% (n=18) of fetuses. The criteria for prenatal diagnosis and its importance in the perinatal support of fetuses and newborns with SCT were determined. Tumor volume growth &gt;100 cm3/week (p=0.0189), tumor-corporal index - TFR&gt;0.12 (p=0.0007), tumor-cranial index - TV:HV &gt;1 (p=0.0006) had a reliable influence on the pathological process, tactics of pregnancy and childbirth. Conclusions. Prenatal diagnosis and dispensation make it possible to detect fetal SCT in advance, to detail its features and to observe the dynamics of the pathological process during different periods of gestation. The developed method of determining the dynamics of fetal tumor growth, as well as the use of the proposed TFR and TV:HV indices, are reliable risk factors that affect the intrauterine passing of the pathological process, the frequency of dispensary monitoring, the tactics of pregnancy management, the terms of hospitalization in the clinic and the delivery of the pregnant woman. The developed classification of tumor growth rate in the fetus within 1 week has important practical significance in predicting the antenatal passing of the pathological process. The research was carried out in accordance with the principles of the Declaration of Helsinki. The research protocol was approved by the Local Ethics Committee of all institutions mentioned in the work. Informed consent of the women was obtained for the research. The authors declare no conflict of interest.

Evaluation of the Immunomodulatory Effects of Radiation for Chimeric Antigen Receptor T Cell Therapy in Glioblastoma Multiforme.

Standard-of-care treatment for Glioblastoma Multiforme (GBM) is comprised of surgery and adjuvant chemoradiation. Chimeric Antigen Receptor (CAR) T cell therapy has demonstrated disease-modifying activity in GBM and holds great promise. Radiation, a standard-of-care treatment for GBM, has well-known immunomodulatory properties and may overcome the immunosuppressive tumor microenvironment (TME); however, radiation dose optimization and integration with CAR T cell therapy is not well defined. Murine immunocompetent models of GBM were treated with titrated doses of stereotactic radiosurgery (SRS) of 5, 10, and 20 Gray (Gy), and the TME was analyzed using Nanostring. A conditioning dose of 10 Gy was determined based on tumor growth kinetics and gene expression changes in the TME. We demonstrate that a conditioning dose of 10 Gy activates innate and adaptive immune cells in the TME. Mice treated with 10 Gy in combination with mCAR T cells demonstrated enhanced antitumor activity and superior memory responses to rechallenge with IL13Rα2-positive tumors. Furthermore, 10 Gy plus mCAR T cells also protected against IL13Rα2-negative tumors through a mechanism that was, in part, c-GAS-STING pathway-dependent. Together, these findings support combination conditioning with low-dose 10 Gy radiation in combination with mCAR T cells as a therapeutic strategy for GBM.

A Comparative Analysis of ARX and ANFIS Models for Tumor Growth Prediction Under Single and Multi-agent Chemotherapy.

Despite the advances in oncology and cancer treatment over the past decades, cancer remains one of the deadliest diseases. This study focuses on further understanding the complex nature of cancer by using mathematical tumor modeling to understand, capture as best as possible, and describe its complex dynamics under chemotherapy treatment. Focusing on autoregressive with exogenous inputs, i.e., ARX, and adaptive neuro-fuzzy inference system, i.e., ANFIS, models, this work investigates tumor growth dynamics under both single and combination anticancer agent chemotherapy treatments using chemotherapy treatment data on xenografted mice. Four ARX and ANFIS models for tumor growth inhibition were developed, estimated, and evaluated, demonstrating a strong correlation with tumor weight data, with ANFIS models showing superior performance in handling the multi-agent tumor growth complexities. These findings suggest potential clinical applications of the ANFIS models through further testing. Both types of models were also tested for their prediction capabilities across different chemotherapy schedules, with accurate forecasting of tumor growth up to five days in advance. The use of adaptive prediction and sliding (moving) data window techniques allowed for continuous model updating, ensuring more robust predictive capabilities. However, long-term forecasting remains a challenge, with accuracy declining over longer prediction horizons. While ANFIS models showed greater reliability in predictions, the simplicity and rapid deployment of ARX models offer advantages in situations requiring immediate approximations. Future research with larger, more diverse datasets and by exploring varying model complexities is recommended to improve the models' reliability and applicability in clinical decision-making, thereby aiding the development of personalized chemotherapy regimens.

Tumor Growth Kinetics Based on Initial Tumor Volume Doubling Time in Active Surveillance of Low-Risk Papillary Thyroid Carcinoma.

Background: During active surveillance (AS) of low-risk papillary thyroid carcinomas (PTCs), the majority remain stable, while some exhibit either an increase or a decrease in tumor diameter or tumor volume (TV). We aimed to evaluate the clinical outcomes and relevant parameters influencing tumor growth kinetics of low-risk PTCs. Methods: This retrospective cohort study evaluated clinical parameters of 402 patients with low-risk PTC sized <2 cm, with a follow-up duration over 3 years. Changes in maximum tumor diameter, TV, and initial TV doubling time (i-TVDT) calculated within 3 years were assessed. A significant change in TV was defined as a change of 75% or more. Results: Of the 402 patients with low-risk PTC, 93.3% (375/402) were diagnosed with papillary thyroid microcarcinoma. During a median follow-up of 5 years, 3.4% (14/402) of patients developed new cervical lymph node (LN) metastasis, and 8.2% (33/402) experienced a maximal diameter increase of ≥3 mm. The i-TVDT of <5 years emerged as an independent risk factor for both maximal diameter growth and new LN metastasis (p < 0.001 and p = 0.04, respectively). Based on TV changes and i-TVDT during AS, we identified four statistically significant tumor kinetic patterns (p < 0.001): Stable (±75% change in TV), Rapid growth (TV increase >75% and i-TVDT <5 years), Slow growth (TV increase >75% and i-TVDT ≥5 years), and Shrinkage (TV decrease >75%). Most of the PTCs remained stable (67.7%), but 17.2% were rapidly growing, with a median onset of growth of 2.0 years. Slowly growing PTCs, comprising 10.9%, grew at a median of 4.3 years. A minority, 4.2%, exhibited shrinkage. In total, 115 (28.6%) patients underwent delayed surgery >12 months after initiating AS. The reasons for delayed surgery included patient preference (51/115, 44.3%), disease progression (31/115, 27.0%), and suspected disease progression, which was referred to as tumor growth not meeting the criteria of an increase of ≥3 mm in maximal tumor diameter (17/115, 14.8%). Conclusion: An i-TVDT of <5 years serves as an important prognostic indicator for disease progression, including tumor growth and new LN metastasis. The four tumor kinetic patterns based on TV changes and i-TVDT assist in guiding personalized decisions early in AS.

Analysis of tumor microenvironment composition in vestibular schwannomas: insights into NF2-associated and sporadic variations and their clinical correlations.

Vestibular schwannomas (VS), benign tumors stemming from the eighth cranial nerve's Schwann cells, are associated with Merlin gene mutations, inflammation, and the tumor microenvironment (TME), influencing tumor initiation, maintenance, and potential neural dysfunction. Understanding TME composition holds promise for systemic therapeutic interventions, particularly for NF2-related schwannomatosis. A retrospective analysis of paraffin-embedded tissue from 40 patients (2013-2020), evenly divided by neurofibromatosis type 2 status, with further stratification based on magnetic resonance imaging (MRI) progression and hearing function. Immunohistochemistry assessed TME components, including T-cell markers (CD4, CD8, CD25), NK cells (CD7), and macrophages (CD14, CD68, CD163, CCR2). Fiji software facilitated image analysis. T-cell markers (CD4, CD8, CD7) exhibited low expression in VS, with no significant NF2-associated vs. sporadic distinctions. Macrophage-related markers (CD14, CD68, CD163, CCR2) showed significantly higher expression (CD14: p = 0.0187, CD68: p < 0.0001, CD163: p = 0.0006, CCR2: p < 0.0001). CCR2 and CD163 significantly differed between NF2-associated and sporadic VS. iNOS, an M1-macrophage marker, was downregulated. CD25, a regulatory T-cell marker, correlated significantly with tumor growth dynamics (p = 0.016). Immune cells, notably monocytes and macrophages, crucially contribute to VS pathogenesis in both NF2-associated and sporadic cases. Significant differences in CCR2 and CD163 expression suggest distinct immune responses. Regulatory T-cells may serve as growth dynamic markers. These findings highlight immune cells as potential biomarkers and therapeutic targets for managing VS.

Abstract PO3-24-02: Molecular characterization and therapeutic approach for VISTA+ triple-negative breast cancers

Abstract Introduction: Current FDA-approved immunotherapeutics for triple-negative breast cancer are only available for a subset of patients, highlighting the need to develop improved immune-targeting strategies. VISTA (V-domain Ig suppressor of T cell activation) is a single-pass transmembrane immune checkpoint receptor that is an emerging clinical target for cancer immunotherapy. It is expressed widely on lymphoid and myeloid cells in healthy individuals, is commonly expressed on cells of the tumor microenvironment and can be abnormally upregulated on tumor cells in a wide variety of tumors. Although VISTA confers quiescence to naïve T cells, molecular mechanisms responsible for this effect remain unclear. Also, the effects of VISTA expression on tumor cells remains poorly defined. Methods: Multi-omic profiling was performed in human breast cancer cells lines to determine immune regulatory genes controlled by growth factor stimulation. Human triple-negative breast cancer tumor specimens (N=248) were examined by immunohistochemistry for expression of VISTA, PDL1, PD1 and FoxP3. VISTA expression was engineered into human and mouse triple-negative breast cancer cell lines and growth metrics were characterized in vitro and in immunocompetent (syngeneic) and immunodeficient (xenograft) mouse tumor models. Membrane receptor trafficking and localization of EGFR was performed in human TNBC cells lines expressing VISTA and VISTA mutants. Proximity biotinylation identified protein partners that interacted with VISTA’s intracellular domain. Deletion mutagenesis was performed to identify motifs required for biochemical interactions between VISTA and clathrin adaptor proteins. Clathrin adapter localization was examined in WT and VISTA knock-out cell lines. Cytokine response, clathrin adaptor localization and tumor growth kinetics were measured in TNBC cell lines expressing VISTA or VISTA mutants. Results: A class of human triple-negative breast cancers were identified with high VISTA expression, low tumor infiltrating lymphocytes and low proliferative index (8-20% of all TNBCs). Tumor models demonstrated that enforced expression of VISTA in tumor cells caused growth suppression, even in the absence of an immune system. This effect was mapped to the cytoplasmic domain of VISTA, which lacks defined signaling domains. Through biochemical approaches, the clathrin-adaptor molecules NUMB and GULP1 were found in complex with a VISTA intracellular NPGF motif. This motif sequestered NUMB at early endosomes, resulting in diminished NUMB recycling for EGFR endocytosis, thereby causing growth suppression. VISTA impaired NUMB recycling by blocking Rab11 effector complex formation. VISTA NPGF mutations did not disrupt cytokine secretion in mixed lymphocyte assays. VISTA-targeted antibodies did not disrupt NUMB sequestration. VISTA+ tumors were selectively sensitive to VISTA-blocking antibodies. Conclusions: VISTA+ TNBC have distinct features including slower proliferative index and increased sensitivity to VISTA-blocking antibodies. This work identifies mechanisms by which VISTA enforces a quiescent cellular state by sequestering clathrin adapter proteins away from sites of endocytosis in cancer cells. This is the first description of intracellular molecular mechanisms controlled by VISTA’s intracellular tail. It may inform features of the VISTA-dependent immune checkpoint that could be exploited to improve anti-tumor immunity. Citation Format: Yan Zhao, Fatima Charles, Andrew Lipchik, Yan Peng, James Ford, Melinda Telli, Song Zhang, Allison Kurian, Michael Snyder, Joshua Gruber. Molecular characterization and therapeutic approach for VISTA+ triple-negative breast cancers [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 PO3-24-02.

3D extension of spatial patterning analysis of cellular ensembles (SPACE) to extract parameters for dynamic tumor modeling

Abstract Investigating the cellular interactions within three-dimensional (3D) tumor microenvironments is essential for understanding tumor growth and progression. Building upon the success of our previous computational framework, SPACE, designed for spatial analysis of high-plex tissue images, we are developing 3D-SPACE. This innovation extends spatial pattern analysis to 3D volumetric tissue images. Volumetric images more accurately capture nuances of cellular arrangements and tissue structures, offering a more realistic representation of the tumor microenvironment. Applying 3D-SPACE to analyze full 3D tumor datasets has the potential to reveal crucial parameters for understanding tumor outcomes. This approach not only elucidates previously undiscovered spatial patterns but also allows for the quantification of parameters such as contact probabilities between different cell types or the killing efficiencies of key effector cells in situ. These spatially-derived parameters can then be used in predictive equations that model and forecast tumor growth based on cellular interactions. Using a 3D tumor model and 3D-SPACE, we can quantify cell interactions and develop predictive equations for tumor growth dynamics, with the aim of deriving a predictive reproduction number (R₀) for tumor growth. Working towards a predictive R₀ for tumor growth offers a valuable approach for predicting tumor growth outcomes. This work was supported in part by the Intramural Research Program of NIAID, NIH.

Abstract P45: REDUCED IMMUNOGENICITY DRIVES SUPERIORITY OF THE NANOLUCIFERASE (NLUC) REPORTER IN AN IMMUNOCOMPETENT GL261 MOUSE GLIOMA MODEL

Abstract Bioluminescence imaging (BLI) with luciferase-based reporters is a robust approach for monitoring tumour growth and treatment response in preclinical in vivo cancer models. Luciferases are considered foreign molecules that could elicit immune responses when introduced in immunocompetent live animal models [1, 2]. The immunogenicity of luciferases and other transgenic imaging reporters, though often overlooked, was recently discussed in relation to mouse cancer models [3-5]. Herein, we investigated the immunogenicity of two luciferase reporters: (1) red-shifted firefly luciferase (RFLuc, 61 kDa) and (2) deep-sea shrimp nanoluciferase (nLuc, 19 kDa) in an orthotopic brain tumour model using GL261 mouse glioma cells in a syngeneic C57BL/6J mouse. We evaluated their suitability for monitoring of brain tumour growth kinetics by BLI. Mice were implanted with 2 × 104 either GL261, GL261-NLuc or GL261-RFLuc cells in the right cerebrum using a stereotaxic device. GL261-RFLuc tumours could only be detected by BLI for 2 weeks, and the mice did not die of disease (median overall survival; mOS &amp;gt; 35 days). In contrast, GL261-nLuc cells formed lethal brain tumours that grew in volume as determined by BLI. GL261-NLuc implanted mice exhibited mOS comparable to mice implanted with GL261 cells (24.5 days vs. 23 days). These observations indicated that nLuc is not significantly immunogenic in mouse brains and did not cause rejection of the tumour cells as observed with RFluc. Cytokine expression profiles and immune cell profiles of the tumour-bearing brain hemispheres were comparable between tumours from GL261 and GL261-NLuc. In contrast, GL261-RFLuc tumours exhibited elevated CD8+ T cells, particularly effector (CD62L¯CD44+) and granzyme B-expressing (GZB+) CD8+ T cells. GL261-nLuc formed stable glioma tumors comparable to the original GL261 mouse model and is a suitable in vivo preclinical model for evaluating experimental therapeutic interventions against gliomas, when paired with Promega’s proprietary fluoro-furimazine substrate. Funding: This research was supported by Singapore’s Health and Biomedical Sciences (HBMS) Industry Alignment Fund Pre-Positioning (IAF-PP) grant H18/01/a0/018 (to AMC) administered by A*STAR and Singapore-MIT Alliance for Research and Technology (SMART) Innovation Grant (ING-000913 BIO) (to AMC). Citation Format: Carla Bianca Luena Victorio, Wisna Novera, Arun Ganasarajah, Joanne Ong, Peter Li, Sven Hans Petersen, Rasha Msallam, Ann-Marie Chacko. REDUCED IMMUNOGENICITY DRIVES SUPERIORITY OF THE NANOLUCIFERASE (NLUC) REPORTER IN AN IMMUNOCOMPETENT GL261 MOUSE GLIOMA MODEL [abstract]. In: Proceedings of Frontiers in Cancer Science; 2023 Nov 6-8; Singapore. Philadelphia (PA): AACR; Cancer Res 2024;84(8_Suppl):Abstract nr P45.

Image-based biomarkers for engineering neuroblastoma patient-specific computational models

AbstractChildhood cancer is a devastating disease that requires continued research and improved treatment options to increase survival rates and quality of life for those affected. The response to cancer treatment can vary significantly among patients, highlighting the need for a deeper understanding of the underlying mechanisms involved in tumour growth and recovery to improve diagnostic and treatment strategies. Patient-specific models have emerged as a promising alternative to tackle the challenges in tumour mechanics through individualised simulation. In this study, we present a methodology to develop subject-specific tumour models, which incorporate the initial distribution of cell density, tumour vasculature, and tumour geometry obtained from clinical MRI imaging data. Tumour mechanics is simulated through the Finite Element method, coupling the dynamics of tumour growth and remodelling and the mechano-transport of oxygen and chemotherapy. These models enable a new application of tumour mechanics, namely predicting changes in tumour size and shape resulting from chemotherapeutic interventions for individual patients. Although the specific context of application in this work is neuroblastoma, the proposed methodologies can be extended to other solid tumours. Given the difficulty for treating paediatric solid tumours like neuroblastoma, this work includes two patients with different prognosis, who received chemotherapy treatment. The results obtained from the simulation are compared with the actual tumour size and shape from patients. Overall, the simulations provided clinically useful information to evaluate the effectiveness of the chemotherapy treatment in each case. These results suggest that the biomechanical model could be a valuable tool for personalised medicine in solid tumours.

Abstract 4182: Development and evaluation of orthotopically and subcutaneously implanted luciferase-labeled prostate cancer xenograft models for therapeutic assessment

Abstract Introduction: Prostate cancer is the most common male-specific cancer in many western countries including the US and the second most prevalent cause of cancer deaths in American males after lung cancer. The establishment of clinically relevant prostate cancer models is crucial for advancing our understanding of the disease and evaluating potential therapeutic interventions. In this in vivo project we characterize the tumor growth and response to therapy of two luciferase (luc) tagged human prostate cancer xenograft models of metastatic PC3M and non-metastatic DU145 cell lines. These models aim to replicate the variable clinical behavior of prostate cancer to provide valuable pre-clinical platforms to test existing and novel therapies. As a first step, these studies evaluate the effect of standard of care cytotoxic agents paclitaxel and carboplatin and the newer AXL kinase inhibitor bemcentinib alone and in combination on tumor growth kinetics and agent tolerability. Methods: PC3M-luc and DU145-luc cells were implanted subcutaneously on right flank or orthotopically into the prostate of NCG triple immunodeficient mice (Charles River). Subcutaneous tumor progression and treatment responses were monitored using calipers and bioluminescent imaging (BLI), with the capacity to detect developing metastases prior to necropsy. Orthotopic implants were monitored exclusively using BLI. Results: Orthotopic and subcutaneous implants of PC3M-luc demonstrated spontaneous metastasis to lungs and bones, replicating the established behavior of this cell line and effectively modeling metastases observed in prostate cancer patients. In contrast, orthotopic and subcutaneous implants of DU145-luc model did not metastasize. Both PC3M-luc and DU145-luc models independent of the tumor implant placement responded to paclitaxel treatment, with enhanced effects observed when combined with carboplatin. Notably, bemcentinib exhibited no activity as a single agent but showed promise when used in combination with cytotoxic agents. Conclusion: The development of orthotopic and subcutaneous PC3M-luc and DU145-luc prostate cancer models provides a valuable platform for assessing the effectiveness of established and novel therapies. These models mimic various clinical presentations of prostate cancer and promise to offer insights into disease progression and therapeutic strategies. Future studies will focus on durable responses and the assessment of other combination therapies for improved treatment outcomes. Citation Format: Kyle Draheim, Elizabeth Rainbolt, Bincy John, Cara Clouse, Andrew Wong, Brooke Wolff, Justin Avery, Chassidy Hall, Patrick Fadden, Anya Avrutskaya. Development and evaluation of orthotopically and subcutaneously implanted luciferase-labeled prostate cancer xenograft models for therapeutic assessment [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 4182.

Abstract 7176: Optimization of T cell co-stimulatory agonists: A semi-mechanistic PKPD model integrating drug properties and tumor-immune interactions

Abstract Background: Despite the success of some immune checkpoint inhibitors in the treatment of cancer, T-cell co-stimulation has faced limited clinical success due to the intricacies around the optimal engagement of agonistic antibodies to co-stimulatory receptors, and the absence of biomarkers for patient selection. Understanding agonist-binding characteristics, pharmacokinetics, T cell subpopulation activation and differentiation kinetics, T cell life span in the tumor microenvironment, and the impact of T cell/tumor interactions on tumor growth kinetics is crucial for the positive clinical outcomes of T cell agonists. Currently there is not a suitable model to describe these complex interactions. Methods: We investigated the pharmacokinetic (PK), pharmacodynamics (PD), and anti-tumor efficacy of an anti-TNFR2 agonist, HFB3-1, and an anti-OX40 agonist, HFB10-1, in syngeneic tumor models. Flow cytometry was employed to profile post-treatment tumor infiltrating lymphocytes (TILs) in dissociated tumor tissues. In vitro binding affinity was determined using Biolayer Interferometry. A semi-mechanistic model, integrating PK, tumor growth, and immune interaction networks (interactions among Teff, Treg, and tumor cells), was developed in Berkeley Madonna (version 10.5.1). This was subsequently adapted to a human tumor growth model with T cell interaction networks to assess the impact of doses and dosing regimens on tumor growth inhibition. Results: A semi-mechanistic PKPD model was successfully developed incorporating drug properties including binding affinity, agonistic effect, ADCC activity, and pharmacokinetics, and tumor growth characteristics including tumor growth kinetics, TIL composition, interaction, proliferation, and turnover. This model was applied to investigate the effect of FcγR, dose, and dosing frequency on in vivo efficacy. Following incorporation of human PK and human tumor microenvironment properties into the model, tumor growth characteristics were simulated under varying human dosing regimens. Simulation results indicated that lower and less frequent doses optimize T cell co-stimulation for optimal anti-tumor activity. Conclusion: Our semi-mechanistic PKPD model elucidates the intricate interactions between T cell co-stimulatory agonists and the tumor-immune cells in the tumor microenvironment. The model advocates for pulsatile agonism as the optimal anti-tumor activity for T cell co-stimulation agents. This model serves as a valuable tool for guiding dose and dose regimen optimization for T cell co-stimulatory agonists in clinical development. Citation Format: Jinping Gan, William Hedrich, Yun-Yueh Lu, Wenhua Xu, Robert H. Andtbacka, Francisco Adrian, Liang Schweizer. Optimization of T cell co-stimulatory agonists: A semi-mechanistic PKPD model integrating drug properties and tumor-immune interactions [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 7176.

Abstract 4191: Delayed onset of GvHD in PBMC humanized NCG-B2m KO mice provides an enhanced model for oncology studies

Abstract Humanized mice are specialized animal models incorporating components of the human immune system. These models are valuable tools for assessing the efficacy of human immunotherapies on tumors. Humanized mice are created by injecting human CD34+ hematopoietic stem cells (HSCs) or human peripheral blood mononuclear cells (PBMCs) into an immunodeficient mouse. PBMC humanized (HuPBMC) mice engraft within a few weeks and can recapitulate a robust human T cell population. One challenge when using HuPBMC mice is the onset of graft versus host disease (GvHD), limiting their lifespan compared to hCD34+ HSC humanized mice. The onset of GvHD varies in the HuPBMC model depending on the donor cells. The development of xenogeneic GvHD is dependent on the expression of major histocompatibility complex (MHC) on host cells and lowering MHC expression can delay the onset of GvHD.NCG-B2m KO mice lack beta-2 microglobulin, a component of MHC I, and have lower cell surface expression of MHC I molecules. This leads to a decrease in recognition of host cells by human immune cells. Here we compared the onset of GvHD between HuPBMC NCG-B2m KO mice and HuPBMC NCG mice. PBMC donor variability was also compared between the two PBMC humanized models by evaluating multiple donors and assessing additional collections from the same donor. After the PBMC engraftment was characterized, HuPBMC NCG mice and HuPBMC NCG-B2m KO mice were enrolled in tumor studies comparing outcomes and tumor growth kinetics in mice treated with human immune checkpoint blockade therapy.NCG and NCG-B2m KO mice were injected with 1x107 PBMCs from individual donors. Animals were weighed three times a week to monitor for changes in body weight and general health status. Peripheral blood was collected at day 10, 20, 30, 40, 60 and 90 post injection for flow cytometry screening of human immune cell engraftment (hCD45+, hCD3+, hCD4+ and hCD8+). Human PBMCs isolated from additional collections from the same donors were also injected into both NCG-B2m KO mice and NCG mice and flow cytometry was performed. HuPBMC NCG-B2m KO mice survived longer than HuPBMC NCG mice allowing for the potential use in longer term tumor studies before the results are confounded by GvHD. PBMC humanized mice are an important model for translational research using immunotherapies and the PBMC humanized NCG-B2m KO model provides an expanded study window ideal for oncology studies. Citation Format: Steven Bronson, David Harris, Anya Avrutskaya, Christoph Eberle, Jenny Rowe. Delayed onset of GvHD in PBMC humanized NCG-B2m KO mice provides an enhanced model for oncology studies [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 4191.

Abstract 7548: Role of bromodomain extra terminal inhibitor (BETi) in combination with radiotherapy for the treatment of NF1-associated malignant peripheral nerve sheath tumor

Abstract Introduction: Neurofibromatosis Type 1 (NF-1) associated malignant peripheral nerve sheath tumors (MPNST) harbor mutations in the polycomb repressive complex 2 (PRC2) in 70% of tumors. PRC2 loss results in epigenetic changes, which increase histone acetylation and make the DNA vulnerable to binding by bromodomain proteins. This interaction could be targeted to uncouple histone acetylation from transcription using bromodomain extra terminal inhibitors (BETi). As radiation therapy (RT) is a cornerstone of MPNST treatment, we analyzed the effects of BETi with and without RT. Methods: Mice were implanted with patient-derived xenografts (PDX) of PRC2-wildtype model developed in the Torres laboratory, MPNST007. Mice were segregated into vehicle and I-BET 762 treatment groups and treated with either vehicle or drug for one week before the RT was initiated. Half of the mice in each treatment group (n = 10) received radiation (2 Gy per fraction for 5 days for a total of 10 Gy). The study endpoints were (1) tumor growth rates, (2) tumor size and weight at study termination, (3) immunohistochemical (IHC) staining for biomarkers of proliferation (Ki67), apoptosis (cleaved caspase 3, CC3), and DNA damage (γH2AX), and (4) RNA sequencing of PDXs from each experimental arm. Results: Significant tumor regression was observed in PRC2-mutant PDX tumors treated with I-BET 762 based on tumor growth kinetics over 45 days of treatment (p &amp;lt; 0.001). Tumor volume was significantly reduced by I-BET 762 compared to vehicle (p &amp;lt; 0.01). Combining I-BET 762 and RT resulted in significant tumor volume reduction (p &amp;lt;0.001). RNA sequencing and intersection of differentially expressed genes related to “DNA damage repair” and those repressed by I-BET 762 was performed for the MPNST007 PDXs. The expression of 259 genes related to DNA damage repair decreased after I-BET 762 treatment, including XRCC1, ERCC4, RAD50, RAD51D, and LIG4 (data not shown). IHC analysis prompted by the RNA sequencing results of the I-BET 762-treated PDXs revealed higher levels of γH2AX. An increase in necrotic and fibrotic tissue with increased CC3 in the BETi plus radiation group was observed. Conclusions: Genetic mutations in NF-1-associated MPNST tumors result in susceptibility to BETi treatment. In a PDX model of PRC2 wild-type tumors, BETi treatment resulted in tumor regression and sensitized MPNST xenografts to RT. Combining BETi and RT enhanced tumor death and increased expression of genes associated with DNA damage and apoptosis. Citation Format: Alcia A. Gingrich, Sharon Landers, Angela Bhalla, Cristian Rodriguez-Aguayo, Rossana Lazcano, Suresh Satpati, Alines Lebron-Torres, Emily Z. Keung, Christopher P. Scally, Christina L. Roland, Kelly K. Hunt, Heather Lyu, Heather Lillemoe, Ashleigh Guadagnolo, Alexander Lazar, John Slopis, Ian McCutcheon, John A. Livingston, Ahsan Farooqi, Kunal Rai, Keila E. Torres. Role of bromodomain extra terminal inhibitor (BETi) in combination with radiotherapy for the treatment of NF1-associated malignant peripheral nerve sheath tumor [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 7548.

Abstract 2840: Development, characterization, and validation of a systemic human mantle cell lymphoma model utilizing luciferase expressing Jeko-1 tumor cells

Abstract Mantle cell lymphoma (MCL) is an aggressive subtype of B-cell non-Hodgkin lymphoma that is clinically and biologically heterogenous. MCL murine models are scarce and reliable in vivo models are necessary for pre-clinical testing and identification of improved novel therapeutics. To address this need, we established and characterized a human MCL in vivo model by systemic implantation of the luciferase-expressing Jeko-1 cell line (Jeko-1-luc) into immunodeficient NCG mice. Tumor growth kinetics was evaluated by testing multiple cell inoculums, and disease progression was monitored by in vivo serial bioimaging, three-dimensional optical imaging (3D), and ex-vivo endpoint analyses. Jeko-1-luc tumor growth profile revealed moderate latency with a median survival of 40 days post implant. Subsequently, we utilized 3D optical imaging and ex-vivo imaging that confirmed the localization of tumor growth predominantly in lungs, spleen, and skeletal regions. Additionally, we determined the surface expression of selected B-cell lineage markers including CD19, CD20, and CD22. Next, we evaluated the efficacy and effect on survival in response to various standard of care agents including Vincristine, Rituximab, Palbociclib, Temsirolimus, and Cyclophosphamide. The quantification of tumor burden by in vivo and ex-vivo bioluminescent imaging demonstrated that the highest therapeutic activity and overall survival was achieved by Palbociclib and Vincristine. Flow cytometric analyses further demonstrated that tumor cells obtained from blood and selected tissues including spleen and bone marrow showed reduced tumor burden in treatment groups relative to the control group. Taken together, these results illustrate the translational value of the Jeko-1-luc model and provides a platform for evaluating novel treatment modalities for mantle cell lymphoma. Citation Format: David Harris, Andrew Wong, Elizabeth Rainbolt, Nicole Westrick, Justin Avery, Joseph Kolb, Aswani Vunnava, Zachary Ward, Chassidy Hall, Bincy John. Development, characterization, and validation of a systemic human mantle cell lymphoma model utilizing luciferase expressing Jeko-1 tumor cells [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 2840.

Abstract 3970: Impairment of tumor reactive CD8 T cells in liver cancer

Abstract Tumor reactive (TR) CD8 T cells in the liver have been studied in the setting of both immunotherapy and cellular therapy with the predominant dogma that these cells have equivalent functionality in the liver as compared to other organ sites. Herein, we detail that TR+ CD8 T cells are functionally impaired in the liver immune microenvironment in mice with liver tumors.TR+ CD8 T cells were studied in BALB/c and C57BL/6 mice injected intrahepatic, intravenous, and subcutaneously with either a colon (CT26) or a melanoma (B16F10) cancer cell line to create intrahepatic, pulmonary and subcutaneous tumors, respectively. Additionally, an ⍺CD8 antibody with IgG control was used to conduct functional studies. Samples were analyzed using flow cytometry and liver weights were measured. A high frequency of TR+ CD8 T cells were found in the liver in mice with intrahepatic tumors. Despite ~70% of CD8 T cells being tumor reactive in intrahepatic tumors, liver tumor growth kinetics were faster than subcutaneous tumors. Higher proportion of the TR+ CD8 T cells were found to be exhausted in the liver tumor by flow cytometry. Functional depletion of the CD8 T cells caused a fivefold higher tumor growth in the subcutaneous model but in contrast had no effect on intrahepatic tumors. In conclusion, despite the high frequency of “killer” tumor reactive T cells in the liver, the growth kinetics of the liver tumors, flow cytometry as well as functional studies demonstrate the impairment of TR+ CD8 T cells in the liver. We aim to dissect the mechanisms mediating intrahepatic TR CD8+ T cell exhaustion in primary liver tumors as well as metastatic models. Additionally, we aim to determine significant costimulatory molecules specific to intrahepatic exhaustion which could lead to better therapeutic models. Citation Format: Rajiv S. Trehan, Marlaine Soliman, Xin Wang, Patrick Huang, Noemi Kedei, Xiao Bin Zhu, Matthias Seifert, Mohamed-Reda Benmebarek, Amran Nur, Firouzeh Korangy, Chi Ma, Tim F. Greten. Impairment of tumor reactive CD8 T cells in liver cancer [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 3970.

Abstract 6904: Model-derived progression-free survival (mPFS): A better metric for patient-derived xenograft studies

Abstract Patient-derived xenografts (PDX) are a powerful assay system for translational prediction of therapeutic potential for experimental therapeutics. The primary readout from PDX models is tumor shrinkage, measured by the ratio of treated/control tumor volume. This readout corresponds loosely to the Objective Response Rate (ORR) metric used in clinical trials, in that it is a readout of drug effect on the sensitive subclones within a tumor. In prior work, we have shown that there is a paradoxical relationship between short-term tumor response and progression-free survival (PFS). While ORR is the primary measure utilized in the Phase II to III transition in clinical development, approval hinges on survival metrics, and the disconnect between ORR and PFS creates a potential risk of late-stage failures for experimental anticancer therapeutics. Thus, it is of interest to understand whether there are alternative approaches to analyzing PDX data that can enable the assessment of therapeutic potential in terms of a projected PFS. In this simulation study, we will examine the accuracy of progression-free survival (PFS) estimates obtained directly from observation during a PDX study and compare their accuracy with the accuracy of PFS estimates derived using a mathematical model-based approach that relies on a kinetic model of tumor subclone growth (model-based PFS, or mPFS) fitted directly to PDX tumor growth and rebound kinetics under treatment. We generated our test dataset using a mathematical model of tumor kinetic growth to simulate xenograft data using fitted parameters derived from literature, adding in experimental error consistent with prior experimental measurement-derived variability. We used the simulated raw data to calculate an observed PFS as well as mPFS derived from fitting the tumor clonal kinetic model to the raw data in a blinded fashion. Our results show that the empirical PFS from PDX models is subject to overestimation, as a function of the observation time interval. On the other hand, mPFS is significantly less biased and more accurate, but is subject to some logistical constraints on sampling. Our work demonstrates the practical translational utility of a novel analysis method (mPFS) in deriving estimates of progression-free survival from PDX model data. Citation Format: Andrew Chen, Madison Stoddard, Lin Yuan, Debra Van Egeren, Arijit Chakravarty, Dean Bottino. Model-derived progression-free survival (mPFS): A better metric for patient-derived xenograft studies [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 6904.

Abstract 3923: Targeting immunosuppressive TREM2+tumor associated macrophages in prostate cancer

Abstract With over 250,000 new cases annually, prostate cancer (PCa) is amongst the most diagnosed cancers in the United States. Despite a near-perfect 5-year survival rate in patients with localized disease with androgen deprivation therapy (ADT), about 10-20% of patients on ADT eventually develop castration-resistant prostate cancer (CRPC). Immunotherapies are typically ineffective in treating these treatment-resistant patients due to the abundance of immunosuppressive tumor-associated macrophages (TAMs) and lack of infiltrating lymphocytes. We propose to target these immunosuppressive macrophages through the triggering receptor expressed on myeloid cells 2 (TREM2), which has been identified as a major mediator of suppressive macrophage function but has not been studied in the context of PCa and CRPC. For this study, we analyzed publicly available RNA-seq datasets to query for TREM2 expression amongst patients with a range of prostate cancer disease states and cell types, measured tumor growth kinetics in two subcutaneous models of prostate cancer, and compared tumor immune infiltrates by flow cytometry. Our analysis of the TCGA prostate adenocarcinoma (PRAD) and the Stand Up to Cancer/Prostate Cancer Foundation (SU2C/PCF) datasets implicate TREM2 expression with prostate cancer progression, by Gleason score and progression-free status, and with worse overall survival of patients with metastatic CRPC (mCRPC). Manual curation and analysis of 10 single-cell RNA-seq datasets with a total of 84 patients, encompassing primary PCa, CRPC, and mCRPC indicate that TREM2 is highly and specifically expressed on TAMs in prostate cancer, with macrophages from patient-matched tumor samples expressing higher TREM2 compared to normal adjacent tissue. B6CaP tumors, with a luminal cytokeratin profile, high AR expression, and high Myc expression, show slower tumor growth in Trem2−/− mice compared to tumors in Trem2wt mice. On the other hand, RM1 tumors show no difference in growth kinetics on Trem2−/− mice. A major difference between the B6CaP and RM1 tumor microenvironments is the level of macrophage infiltration, where only 2-5% of immune cells in RM1 tumors are macrophages, compared to the 40-50% in B6CaP tumors. RM1 cells co-implanted with Trem2−/− macrophages show slower tumor growth, compared to tumor cells co-implanted with Trem2wt macrophages, confirming the role of Trem2-expressing macrophages in mediating tumor growth. Consistent with previous reports of suppressive Trem2 signaling, we also observed higher levels of inflammatory cytokine production in ex vivo stimulated Trem2−/− TAMs. By targeting TREM2 in prostate cancer, we find that TAMs are less suppressive, more inflammatory, and permit cytotoxic lymphocyte infiltration to enhance anti-tumor responses by synergizing with chemo and immune checkpoint therapy. Citation Format: Alex J. Lee, Kenneth Adusei, Monali Praharaj, Fan Shen, Xiaoxu Wang, Kaavya Bhatia, Thomas Nirschl, Jelani C. Zarif. Targeting immunosuppressive TREM2+tumor associated macrophages in prostate cancer [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 3923.

Abstract 2841: Development and validation of a systemic human multiple myeloma model utilizing luciferase expressing MM1.S tumor cells

Abstract Multiple Myeloma (MM) is a complex hematologic malignancy characterized by clonal proliferation of transformed plasma cells leading to overproduction of monoclonal immunoglobulins and subsequently end-stage organ damage. Despite therapeutic advances, MM is an incurable disease with poor prognosis in high-risk patients, and thus relevant preclinical models are necessary to develop novel treatment strategies. We developed a Multiple Myeloma in vivo model by systemic implantation of the luciferase-expressing glucocorticoid sensitive tumor cell line MM1.S (MM1.S-Luc) into immunodeficient NCG mice. First, we generated a MM1.S-Luc monoclonal cell line from a polyclonal pool of stable luciferase-expressing cells by limiting dilution. Single cells from the stable pool were expanded under selective pressure and four MM1.S-Luc monoclonal lines were selected based on in vitro growth properties and bioluminescence intensity. Next, we determined the in vivo tumor growth profile by testing the monoclonal lines at two different cell inoculums, and disease progression was monitored by in vivo serial bioimaging. MM1.S-Luc tumor growth kinetics revealed a long latency and based on our in vivo imaging results, the tumor preferentially localized to the long bones, lungs, and mandible. For validation of the MM1.S-Luc in vivo model, we determined the efficacy and survival benefit in response to various clinically relevant standard of care agents including Dexamethasone, Daratumumab, Cyclophosphamide, Vincristine, Panobinostat, and Bortezomib. The quantification of tumor burden by bioluminescent imaging showed reduced tumor burden and prolonged survival with Panobinostat and Cyclophosphamide. In summary, we have developed a systemic MM1.S-Luc model that recapitulates the disease dissemination and invasiveness of multiple myeloma for evaluating novel therapeutic approaches to treatment. Citation Format: Bincy John, Christopher Currie, Nicole Westrick, Tyler Rowe, Andrew Wong, Elizabeth Rainbolt, Zachary Ward, Chassidy Hall, David Harris. Development and validation of a systemic human multiple myeloma model utilizing luciferase expressing MM1.S tumor cells [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 2841.

Abstract 1453: Development and evaluation of subcutaneous and orthotopic PC3M metastatic prostate cancer xenograft model in SRG rats for therapeutic assessment

Abstract Introduction: Prostate cancer is the most prevalent cause of cancer deaths in American males after lung cancer. The establishment of clinically relevant prostate cancer models is crucial for advancing our understanding of the disease and evaluating potential therapeutics. Oncology studies in rats provide a secondary species to mice with the advantage of extensive longitudinal blood sampling and tumor biopsies in pharmacodynamics analysis. This in vivo study evaluates the behavior of subcutaneous and orthotopic luciferase (luc) tagged metastatic PC3M-luc cells in immunodeficient SRG rats (Hera Biolabs) for tumor growth kinetics, metastasis, and response to paclitaxel and carboplatin alone and in combination. Methods: PC3M-luc cells were implanted subcutaneously into the right flank or orthotopically into the prostate of SRG rats. Subcutaneous tumor progression and treatment responses were monitored using calipers and bioluminescent imaging (BLI), with the capacity to detect developing metastases prior to necropsy. Orthotopic implants were monitored exclusively using BLI. Tolerability was evaluated based on biweekly changes in body weight, daily observations for signs of tumor- or treatment-related clinical signs, necropsy results, and complete blood count (CBC) and clinical chemistry marker comparisons with immunocompetent CD rats. Results: PC3M-luc prostate carcinoma was successfully established orthotopically and subcutaneously in SRG rats, with similar growth rates and the development of spontaneous metastases to distant organs, modeling metastases observed in prostate cancer patients. Paclitaxel treatment was less tolerated in SRG rats in comparison to nude rats, enhanced toxicity was observed when combined with carboplatin. Comparison of CBC and clinical chemistry blood markers in naïve immunocompetent CD and immunodeficient SRG rats differed mainly in White Blood Cell (WBC) counts that were significantly lower in SRG rats, as expected due to the lack of mature B, T, and NK cells in these animals. Conclusion: The development of orthotopic and subcutaneous PC3M-luc prostate cancer models in rats provides a valuable alternative platform for assessing the effectiveness of established and novel therapies. This rat-based models offers a secondary species for comparison of prostate cancer behavior in mice, successfully mimics the clinical development of metastases, and provides additional insights into disease progression and therapeutic strategies. Future studies will focus on the assessment of tolerability and combination therapy strategies for improved treatment outcomes. Citation Format: Kyle Draheim, Elizabeth Rainbolt, Bincy John, Cara Clouse, Karyn Shinn, Justin Avery, Koh Meng Aw Yong, Chassidy Hall, Patrick Fadden, Anya Avrutskaya. Development and evaluation of subcutaneous and orthotopic PC3M metastatic prostate cancer xenograft model in SRG rats for therapeutic assessment [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 1453.