Citations

Abstract Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant condition characterized by plasma cell production of monoclonal (M) protein and is a requisite precursor to multiple myeloma (MM). African American (AA) individuals have a two-fold higher incidence of MGUS and MM compared to White individuals. However, data are limited on individuals from Africa, especially using sensitive MGUS detection methods. We examined the prevalence of MGUS in a sample of the general population in Nigeria. Individuals aged 40 and over (n=343) were recruited through health promotion events in Ado-Odo Ota Local Government Area of Ogun State, Nigeria, and provided informed consent, a blood sample, and a short questionnaire. Serum was screened at Mayo Clinic for heavy chain (HC)-MGUS using the matrix-assisted laser desorption/ionization-time of flight (Mass-Fix) assay, which has high sensitivity for detection of M-proteins; serum free light chains (FLC) were also measured. FLC was abnormal if the kappa (>0.26 mg/dL) or lambda (>0.33 mg/dL) light chain (LC) was elevated and FLC ratio (kappa/lambda) was outside the reference range (0.26-3.10). LC-MGUS was defined as an abnormal FLC in the absence of a HC. Age- and sex-adjusted prevalence rates were directly standardized to 2010 United States (US) population for comparison to published studies. Logistic regression was used to examine the association of age, sex, and BMI with HC-MGUS. The mean age of participants was 55 years (SD=10.9), and 74.6% were female. Of these, 216 (63%) had both parents from the Yoruba tribe, 89 (26%) from the Igbo tribe and 38 (11%) from other tribes. Overall, 33 participants (9.6%) had HC-MGUS, with 8 (2.3%) having an M-protein above 0.2 g/dL; 6 (1.7%) had LC-MGUS. HC-MGUS was predominantly IgG isotype (48.5%), followed by IgA (27.3%), biclonal (15.2%) and IgM (9.0%). Prevalence of HC-MGUS was 8.3% for ages 40-49, 7.7% ages 50-69 and 22% ages 70 and above. Standardized to the US population, age and sex adjusted MGUS prevalence ages 50 and older was 17.3% (95% CI: 9.8%-24.9%) and HC-MGUS was 14.7% (95% CI: 7.7%-21.8%), similar to previously published rates of HC-MGUS using Mass-Fix screening of AA individuals (16.5%, 95% CI: 12.2%-20.8%) (PMID: 35316833). In models that included age, sex and BMI, older age was positively associated with HC-MGUS (OR=3.1, 95% CI: 1.1-8.7 for ages 70+ compared to <50), while female sex (OR=0.53, 95% CI: 0.24-1.2) and overweight/obesity (OR=0.34, 95% CI: 0.16-0.75 for BMI > 25 vs. <25) were inversely associated with HC-MGUS. We observed similar prevalence of HC-MGUS at ages 50 and above among Western Nigerian and AA populations when screened using mass-spectrometry. Older age was positively associated with HC-MGUS while overweight and obesity were inversely associated. Studies of MGUS in indigenous African populations may provide insight to unique cancer risk factors compared to other populations. Citation Format: Celine M. Vachon, Cristine Allmer, Danelle Moonen, Aaron Norman, Joselle Cook, Susan Slager, Oluwakemi A. Rotimi, Opeyemi C. De Campos, Titilope M. Dokumu, David Murray, Shaji Kumar, Elizabeth Brown, Linda B. Baughn, Solomon Rotimi. Prevalence of monoclonal gammopathy of undetermined significance (MGUS) in a Western Nigerian population [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 3455.

Abstract Breast cancer (BC) remains a leading health concern worldwide and is often undetected until the cancer metastasizes. Early detection can limit the need for aggressive treatments and improve prognosis. We analyzed early immune and molecular markers in benign breast disease (BBD) biopsies prior to BC development to identify women at elevated risk of developing node-positive invasive BC, which might direct surveillance and prevention efforts aimed at reducing incidence of this disease. Utilizing the Mayo Clinic BBD cohort, we compared women who developed node-positive BC following their BBD biopsy (cases; n=42) with those who remained cancer-free (controls; n=37), matched on patient age and biopsy date. We used NanoString nCounter system to identify differentially expressed genes (DEGs) between cases and controls. We also developed a multiplex immunofluorescence (mIF) approach using Opal system by Akoya Biosciences for comprehensive marker detection in FFPE tissue, enabling correlation of cells expressing DEGs with innate and adaptive immune cells. Digitized images were segmented, and cell phenotyping, and spatial relationships were compared between cases and controls. Our findings revealed significantly increased expression levels of IRF8 (interferon regulatory factor 8, a factor involved in immune cell differentiation) in controls as compared to cases and found that increased IRF8 expression in cases is correlated with delayed cancer onset. Additionally, controls exhibited higher frequencies of CD4+, CD8+, CD68+, CD20+ and CD11c+ immune cells, and lower frequency of Ki67+ staining, with a notable increase of CD11c+/CD68+ cells, a marker for M1 type macrophages, indicating a pro-inflammatory, antitumorigenic immune microenvironment polarization. Furthermore, our mIF analyses offer new insights into spatial biomarker localization, enhancing prognostic accuracy. Our findings suggest that decreased numbers of immune cells in BBD biopsies may be associated with increased risk of developing axillary node-positive BC. This research underscores the importance of dissecting molecular and immune interactions in BBD for assessing the risk of this disease. Our results have the potential to improve individualized risk assessment, leading to more targeted surveillance and informed screening, potentially reducing BC incidence and mortality through early intervention. This study not only contributes to our understanding of BC pathogenesis but also opens avenues for developing novel preventive strategies. Citation Format: Matilde Rossi, Nicole Cruz-Reyes, Melody L. Stallings Mann, Bryan M. McCauley, Tanya L. Hoskin, Robert A. Vierkant, Stacey J. Winham, Amy C. Degnim, Mark E. Sherman, Derek C. Radisky. Interferon regulatory factor 8 (IRF8) as a biomarker for early detection and prevention of axillary lymph node-positive breast 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 4773.

Abstract Background: Multi-cancer early detection (MCED) tests are being established as a novel approach to screen for multiple cancer types with one test. A blood-based MCED test using cell-free DNA targeted methylation patterns to detect a shared cancer signal and predict a cancer signal origin (CSO) has demonstrated feasibility. An initial return of results study (PATHFINDER; NCT04241796) reported performance of a refined version of the MCED test, including a 43.1% positive predictive value (PPV), 98.5% negative predictive value (NPV), 99.5% specificity, and 88.0% CSO accuracy. To build on this work, the PATHFINDER 2 study (NCT05155605) will evaluate safety and performance of the MCED test in larger, more diverse populations. Methods: PATHFINDER 2 is a prospective, multicenter, interventional study. Participants ≥50 years of age will be enrolled, with specific targets to improve diversity (age, sex, race/ethnicity) and few exclusions due to comorbid conditions. Exclusion criteria include current clinical suspicion of cancer or recent cancer/treatment (within 3 years). Participants will undergo blood draw for MCED testing, followed by return of results (cancer signal detection and CSO) to the investigator and diagnostic evaluations if a cancer signal is detected. A confirmatory PET-CT scan will be performed when CSO-directed workups do not result in a cancer diagnosis. Participants will be followed for approximately 3 years. Primary endpoints include 1) MCED test safety in terms of diagnostic testing triggered by a positive result (number/type of procedures and adverse events) and 2) test performance (PPV, NPV, specificity, sensitivity, CSO accuracy, cancer detection rate and number needed to screen). Secondary endpoints include participant reported outcomes (eg, anxiety), utilization of guideline-recommended cancer screening, and cancer detection rate of confirmatory PET-CT, amongst others. The study plans to enroll approximately 35,000 participants across North America. Sites were selected based on geographic location, catchment area demographics, and practice setting (academic vs non-academic). Enrollment targets for age, sex and race/ethnicity (White [non-Hispanic] 72%; Hispanic or Latino 11%; African American or Black 11%; Asian, Native Hawaiian or Other Pacific Islander 6%; American Indian/Alaska Native 1%) were derived from US Census data. Strategies to promote diverse recruitment include translation of participant-facing documents across multiple languages, participant and healthcare provider educational material, and site-led community outreach campaigns. MCED testing is an emerging, potentially paradigm-changing strategy in cancer screening, and PATHFINDER 2 is designed to characterize the safety, performance, and clinical implementation of the MCED test as a screening tool in a broad and representative population. Citation Format: Karthik V. Giridhar, Michael J. Demeure, Raymond H. Kim, Justin A. Chen, Shirish Gadgeel, Dax Kurbegov, Margarita Lopatin, Roland Matthews, Marc Matrana, Charles McDonnell, Donald Richards, Benjamin Rybicki, Gretchen Stipec, Nima Nabavizadeh. PATHFINDER 2: A prospective study to evaluate safety and performance of a multi-cancer early detection test in a population setting [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 4784.

Abstract CD19-directed chimeric antigen receptor T (CART19) cell therapy has shown remarkable outcomes in B cell malignancies and was FDA approved in multiple indications, but durable remissions are limited to ~40%. Inhibitory myeloid cells in the tumor microenvironment have been found to suppress T cell expansion and contribute to CART19 failure. Here, we studied interactions between monocytes, CART19, and tumor cells to understand the impact of monocytes on CART19 effector functions. First, CD28-costimulated CART19 (CART19-28ζ) generated in the lab from healthy donors were cocultured with JeKo-1, a CD19+ mantle cell lymphoma cell line, and freshly isolated monocytes or ex vivo differentiated M2-like macrophages. M2-like macrophages were generated by incubating fresh monocytes with rhGM-CSF followed by coculturing with JeKo-1. CART19 antigen-specific proliferation was significantly inhibited by M2-like macrophages but not fresh monocytes (JeKo-1+CART19 vs JeKo-1+M2+CART19, p=0.00503). Transwell assays indicated that suppression from M2-like macrophages was not contact-dependent. IL-1 receptor antagonist (IL-1ra) was significantly elevated in M2-like macrophage coculture supernatant (JeKo-1+Mono+CART19 vs JeKo-1+M2+CART19, p=0.0292) and intracellularly in M2-like macrophages after coculture (90%+). We therefore hypothesized that M2-like macrophages inhibit CART19 by secreting IL-1ra, which blocks IL-1 signaling in CART19. We interrogated the role of IL-1ra in CART19. JeKo-1 was cocultured with CART19, supplemented with rhIL-1β only, IL-1β + IL-1ra, or IL-1β +IL-1ra + IL-1ra neutralizing antibody (neuAb). CART19 antigen-specific proliferation was improved by IL-1β (PBS vs IL-1β, p<0.0001). IL-1ra inhibited IL-1β-dependent CART19 proliferation (IL-1β vs IL-1β+IL1ra p=0.0006), which was restored by IL-1ra neutralization (IL-1β+IL-1ra vs IL-1β+IL-1ra+IL-1ra neuAb, p=0.0215). Additionally, expression of IL-1RI, the receptor of IL-1β and IL-1ra, was measured on T cells after coculturing CART19, JeKo-1, and M2-like macrophages. M2-like macrophages downregulated IL-1RI expression on CART cells, which is a potential mechanism of blocking CART response to IL-1β, resulting in further suppression of CART proliferation (JeKo-1+M2+CART19 vs JeKo-1+CART19, p=0.001). Next, we assessed the impact of IL-1ra on CART cell functions in the presence of M2-like macrophage in a mantle cell lymphoma xenograft model. NOD-SCID-γ−/- (NSG) mice were subcutaneously injected with human macrophages and luciferase+ JeKo-1 cells. Upon tumor engraftment by bioluminescent imaging, mice were randomized to treatment with CART19 + IL-1ra neuAb or control IgG for 3 weeks. CART19 + IL-1ra neuAb led to improved antitumor activity (IL-1ra neuAb vs control IgG, p=0.0033). Overall, our study revealed a role of IL-1ra in macrophage-induced CART inhibition mediated by blocking IL-1β signaling through IL-1RI. Citation Format: Kun Yun, Reona Sakemura, Truc Huynh, Claudia Manriquez Roman, Olivia Sirpilla, Carli Stewart, James Girsch, Ekene Ogbodo, Ismail Can, Jennifer Feigin, Long Mai, Hong Xia, Brooke Kimball, Makena Rodriguez, Lionel Kankeu Fonkoua, Mehrdad Hefazi, Michael Ruff, Elizabeth Siegler, Saad Kenderian. Immunosuppressive monocytes suppress CART19 functions through modulation of the IL-1 pathway [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 6813.

Abstract Glioblastoma remains difficult to treat with immunotherapy due to the immunosuppressive tumor microenvironment and the ability of glioma cells to invade diffusely into normal brain parenchyma. While it is known that glioblastoma-associated myeloid cells (GAMs) comprise a large proportion of the tumor microenvironment and can suppress adaptive and innate immune responses through various mechanisms, detailed mapping of myeloid lineages in glioblastoma is still missing. Further characterization of pro-tumoral myeloid-lineages in glioblastoma is important for identifying myeloid-based drug targets that may synergize with T cell-based therapies and produce a more meaningful anti-tumor immune response. Towards this end, we examined numerous scRNAseq datasets derived from glioblastoma patients and identified expression of TNFRSF12A, the gene encoding the TNF- family receptor, Fn14, in a subset of GAMs enriched for expression of cytokines such as CCL3, CCL5, IL-6, and IL-8. This result is intriguing since TWEAK (TNFSF12), the ligand for Fn14, is abundantly expressed within numerous patient-derived glioblastoma cell lines, namely GBM6, GBM8, GBM22, and GBM39. To validate Fn14 protein expression in GAMs, we isolated murine bone-marrow derived macrophages and treated them with glioma-conditioned media, which induced Fn14 gene expression. We then conducted in vitro experiments utilizing the human microglia line HMC3, the murine microglia line SIM-A9, and primary murine bone-marrow-derived macrophages to assess the effects of Fn14 activation in myeloid cells. We found that treatment of Fn14+ myeloid cells with TWEAK ligand upregulates CCL3, CCL5, IL-6, and IL-8 expression. We tested the conditioned media generated from TWEAK-treated Fn14+ myeloid cell lines and found that it promotes glioblastoma invasion in a CCL5-dependent manner. This aligns with previous reports demonstrating the CCL5-CCR5 signaling in glioma cells promotes invasion through calcium-dependent matrix metalloproteinase 2. To assess the spatial distribution of this myeloid subpopulation, we performed RNAscope hybridization against AIF1, TMEM119, CCR5, CCL5, and Fn14 transcripts on sections of murine gliomas generated using the RCAS/tv-a model of human glioblastoma. We found an abundance of Fn14+ plus AIF1+ as well as Fn14+plus TMEM119+ myeloid cells throughout the tumor core and rim of murine tumors and identified CCL5 expression in pseudo-palisades bordering necrotic regions. Our results to date suggest that Fn14 expression in GAMs can promote the invasion of tumor cells into normal brain parenchyma by release of CCL5. Currently, we are utilizing orthotopic patient-derived xenograft models co-implanted with Fn14+/- myeloid cells to test the hypothesis that TWEAK-Fn14 signaling in GAMs provides strong pro-tumoral signals in the glioblastoma microenvironment. Citation Format: Angad Beniwal, Matthew Dufault, Pranjali Kanvinde, David Nascari, Ryan Eghlimi, Adarsha Malla, Dolores Hambardzumyan, Henrique Borges da Silva, Graeme Woodworth, Jeffrey Winkles, Nhan Tran. TWEAK-Fn14 signaling in glioblastoma-associated myeloid cells promotes tumor invasion via CCL5-CCR5 axis [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 6867.

Abstract Introduction: Despite the enactment of the 1993 NIH Revitalization Act to improve accrual of women and minorities in clinical trials, these groups remain underrepresented. This study aims to uncover drivers of therapeutic clinical trial enrollment that are unique to women and minority patients with low- and high-grade glioma. Methods: Adult glioma patients who received care from the UCSF Brain Tumor Center between 1997-2017 were identified in a prospective registry. Dividing the cohort into subgroups by gender and NIH-designated minority status, factors associated with therapeutic clinical trial enrollment on univariate logistic regression (p<0.2) were selected for multivariate logistic regression. Results: There were 351 trial participants (41% women, 12% minority) and 627 non-trial participants (44% women, 17% minority). Among women only, seizure at presentation (OR 2.10, p=0.008) was associated with increased odds of trial enrollment. In contrast, among men only, higher median household income (OR 1.09 per $10,000 increase, p=0.006), higher WHO tumor grade (OR 1.89, p=0.045), and occupational status according to the International Standard Classification of Occupations [professionals (e.g., physicians) vs managers (e.g., supervisory positions), OR 2.87, p=0.043] were associated with increased odds of trial enrollment. Among both women and men, lack of insurance (women: OR 0.49, p=0.02; men: OR 0.55, p=0.031) and no treatment with chemotherapy (women: OR 0.18, p=0.001; men: OR 0.34, p=0.002) were associated with decreased odds of clinical trial enrollment, whereas higher KPS (women: 90 vs <80, OR 3.16, p=0.003; men: 90 vs <80, OR 3.15, p=0.002) was associated with increased odds of trial enrollment. Among NIH-designated minority patients, older age (OR 0.66 per 10-year increase, p=0.033) and non-English preferred language (OR: 0.30, p=0.035) were associated with decreased odds of trial enrollment on univariate analysis, but not on multivariate analysis. Among non-minority patients, lack of insurance (OR 0.58, p=0.008) and no chemotherapy treatment (OR 0.25, p<0.001) were associated with decreased odds of trial enrollment, whereas seizure at presentation (OR 1.80, p=0.001), higher neighborhood household income (OR 1.07 per $10,000 increase, p=0.004), higher WHO grade (4 vs 2-3, OR 1.86, p=0.015), higher KPS (90 vs <80, OR 3.21, p<0.0001), and lower extent of tumor resection (80-89% vs 100%, OR 2.16, p=0.047) were associated with increased odds of trial enrollment. Conclusion: Drivers of trial enrollment differed for women and minority patients with glioma. Non-English-speaking minority patients may face additional barriers to trial enrollment requiring targeted interventions. Our findings can revitalize and tailor efforts to recruit women and minority patients to therapeutic clinical trials in neuro-oncology. Citation Format: Mulki Mehari, Gayathri Warrier, Sheantel Reihl, Abraham Dada, Aymen Kabir, Mikias Negussie, Cesar Nava Gonzales, Ugonma Chukwueke, Alyx Porter, Shawn Hervey-Jumper. Revitalizing the accrual of women and minorities: Unique drivers of therapeutic clinical trial enrollment for underrepresented patients with diffuse glioma [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 1006.

Abstract BACKGROUND: Cancer is typically treated with a combination of drugs rather than monotherapy stratagems, but identification of synergistic drug combinations for the treatment of cancers is challenging. Here we present the combination of PARP and Aurora Kinase inhibitors synergize through induction of the ferroptosis pathway of cell death. METHODS: We identified these drugs through an unbiased screen of enriched drug class response correlations. We then validated a synergistic cell killing effect of multiple drugs of each class by in vitro drug screening. Next, we performed reversal experiments using a ferroptosis inhibitor and lipid peroxide staining to confirm ferroptosis is a relevant cell death pathway. We performed Western immunoblot analysis in cells overexpressing putative Aurora Kinase phospho-substrates in the relevant pathway of interest, and performed site directed mutagenesis experiments to show the relevant amino acid altered by kinase activity. We also performed a series of qPCR and co-IP experiments to show PARPi effect on the antioxidant signaling pathway. RESULTS: We validated and identified synergy in a prostate cancer specific context. Next, we found Talazoparib and Alisertib induced ferroptosis after synergy was reduced with a ferroptosis inhibitor and lipid peroxides increased accumulation. We found a novel mechanism action for Alisertib, wherein Aurora Kinase inhibitors can alter the phospho-status and activity of the iron reduction enzyme Steap3.We also found that PARP inhibitors can affect the Nrf2-driven antioxidant signaling pathway on a transcriptional level. CONCLUSION: Aurora Kinase inhibitors and PARP inhibitors for the treatment of prostate cancer was identified and was validated as synergistic, which revealed new functional roles of both drugs in the context of cell killing. These findings represent a new clinical combination of drugs in prostate cancer and reveal a novel role for this drug class in ferroptosis. Citation Format: August John, Kuntian Luo, Zhenkun Lou, Liewei Wang. Ferroptotic mechanism of drug induced toxicity of PARPi and AurKi 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 4563.

Abstract Radiation therapy (RT) is a cornerstone of oncologic therapy for the majority of solid malignancies, and unrepaired DNA double-strand breaks are responsible for radiation-induced cytotoxicity. RT-induced DNA lesions can be repaired by multiple mechanisms including homologous recombination (HR) and non-homologous end joining (NHEJ), and disruption of either of these pathways can enhance cytotoxicity. A key component of the NHEJ pathway is the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), and loss of kinase activity can significantly increase radiosensitivity. Herein we describe the results of our medicinal chemistry campaign to develop a potent and selective DNA-PKcs inhibitor, WNC0901. WNC0901 inhibits DNA-PKcs kinase activity in a cell free system with an IC50 of 0.071 nM and demonstrated at least 30-fold higher sensitivity than other family members (ATM, ATR, mTOR, PI3K). WNC0901 has limited aldehyde oxidase (AO) liability with a T1/2 >2000 min in liver cytosol and is stable for over 120 minutes in the presence and absence of an AO inhibitor. A preliminary pharmacokinetic analysis in wista han rat (IV=2mg/kg, PO=20mg/kg) demonstrated 116% apparent absolute oral bioavailability, 2.6 hour terminal half-life, 33.0 mL/min/kg clearance, and a 2.6% unbound brain-to-plasma partition coefficient (Kpuu). WNC0901 also had favorable pharmacokinetic properties in beagle dog (IV=2mg/kg, PO=20mg/kg) with moderate clearance (8.5 mL/min/kg), high apparent absolute oral bioavailability (131%) with good exposure (AUC=36092 h*ng/mL), moderate half-life (4.28 h), and low protein binding (74.3% fraction unbound). The volume of distribution was moderate in both species (Vss = 1.32 L/kg in wistar han rat and 1.87 L/kg in beagle dog). In cell culture, WNC0901 inhibited autophosphorylation of DNA-PKcs in HT29 cells irradiated with 10 Gy with an IC50 of 32.7 nM and robustly inhibited autophosphorylation in both U251 glioma and A549 lung cancer cell lines at 300 nM in combination with 5Gy. In a clonogenic assay, 5Gy irradiation (10% survival) combined with 100nM WNC0901 demonstrated modestly enhanced cell killing (1.5% survival), and maximal effects were seen at 300nM (0.04% survival, p<0.01). Similar radiosensitizing effects with 300 nM WNC0901 were seen in the A549 cell line (0.2% survival with combination compared to 19% with 5Gy alone, p<0.01). In summary, WNC0901 inhibits DNA-PK kinase activity and provides potent radiosensitization in a GBM and lung cancer cell line. Future studies will assess the combination of WNC0901 and RT in GBM patient-derived xenograft models in vivo. Citation Format: Ann C. Mladek, Danielle L. Burgenske, William F. Elmquist, Wei Zhong, Jann N. Sarkaria. Preclinical data of a novel DNA-PK inhibitor in combination with radiation therapy shows promise in the treatment of established GBM and lung carcinoma cell lines [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 701.

Abstract Background: Triple-negative invasive lobular carcinoma (TN-ILC) is a rare (0.1-1.4%) breast cancer with prognosis worse than ER positive ILC. Currently there are no targeted therapies or clinical trials specifically for TN-ILC. A comprehensive analysis of the molecular and immune landscape can help identify novel targets and pathways for TN-ILC to improve patient outcomes. Here, we characterized the molecular and immune signature of TN-ILC. Methods: 11,760 breast cancer samples (Invasive ductal (ID) TNBC, n=364; TN-ILC, n=31) were analyzed (592, NextSeq; WES, NovaSeq), (WTS; NovaSeq) (Caris Life Sciences, Phoenix, AZ). Tumor mutational burden (TMB) totaled somatic mutations per tumor (high ≥10 mt/MB) was tested by NGS. Microsatellite-instability (MSI) was tested by NGS. Immune cell fractions were calculated by deconvolution of WTS. Statistical significance was determined using chi-square and Mann-Whitney U test with p-values adjusted for multiple comparisons (q < 0.05). Results: TN-ILC had higher frequency of CDH1 (0.83% vs. 66.67%), ERBB2 (0.84% vs.28.57%), ARID1A (1.65% vs. 23.33%), CBFB (0.55% vs.16.67%), AKT1 (2.22% vs.16.13%) and KMT2C (3.83% vs.13.79%), but lower frequency of TP53 (89.7%5 vs. 38.71%) mutations (all p<0.05) compared to ID-TNBC. TN-ILC had higher frequency of TMB high (23.3% vs. 5.2%, p<0.05) but there was no difference in dMMR/MSI-H (0% vs 1.1%, p=1). TN-ILC had higher AR RNA (FC: 14.2), protein expression (80.6% vs. 24.8%) and higher frequency of fusion variant-AR (16.1% vs 4.9%) (all p < 0.05) compared to ID-TNBC. Analysis of inferred immune cell infiltrates showed that TN-ILC had higher infiltration of M2 macrophages (5.34% vs. 2.94%) and neutrophils (4.83% vs. 2.65%) but lower infiltration of M1 macrophages (3.46% vs 2.17%) and CD8 T cells (0.58% vs. 0.11%) (all p<0.05). TN-ILC had lower T cell inflamed signature (16.1% vs 35.7%, p<0.05), decreased immune checkpoint genes (CD274, CTLA4, FOXP3, LAG3, IDO, FC: 1.2-2.7, all p < 0.05), PD-L1 protein expression (SP142: 30.4% vs. 50.2%, p=0.06; 22c3: 15.4% vs. 42.6%, p = 0.05) and differential expression of BCL2 family genes (upregulation: BIK, FC: 2.2; downregulation: BAX, BAK1, BID, PMAIP1, MCL1, BCL2A1, BCL2L10, FC: 1.0-6.3, all p < 0.05) compared to ID-TNBC. Conclusion: These data suggest that TN-ILC had higher frequency of CDH1, ERBB2, AKT1, ARID1A mutations, higher M2 macrophages and neutrophils and lower M1 macrophages and CD8 T cells infiltration and, lower T cell inflamed signature. High TMB and AR expression can translate into use of immunotherapy (ICI) and AR antagonists in these patients. Additonal analysis to determine the optimal biomarker for ICI response in TN-ILC is needed. Results of our study need to be validated in larger studies with survival correlation. Citation Format: Pooja Advani, Sachin Deshmukh, Sharon Wu, Jacob Andring, Joanne Xiu, Jose Leone, Priya Jayachandran, Stephanie Graff, Mathew Oberley, George Sledge, Asher Chanan-Khan. Comprehensive molecular and immune profiling of triple negative invasive lobular carcinoma [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 7037.

Abstract Background: The need to increase understanding of prostate cancer (CaP) is ever increasing. Unfortunately, there is limited understanding of how CaP affects men of African ancestry (MAA) despite significant disparities in CaP prevention, diagnosis, and treatment due to genetic and sociobehavioral factors. Conducting CaP clinical trials (CTs) in Africa presents multiple opportunities to improve upon collective knowledge of CaP in MAA experiences, expand patient access to CTs, and provide opportunities for African scientists and urologists to contribute to research on the global stage. The International Registry of Men with Advanced Prostate Cancer (IRONMAN) seeks to reduce CaP disparities by sponsoring sites throughout Africa. Four Prostate Cancer Transatlantic Consortium (CaPTC) institutions in Nigeria currently participate in IRONMAN: University of Ilorin Teaching Hospital, Federal Medical Center, University of Maiduguri, and Lagos State University Teaching Hospital. Because CTs of this scale are infrequently conducted in Africa, there are special considerations when conducting CTs in low-middle-income countries (LMICs) like Nigeria. Methods: Hourlong interviews dedicated to site staff were conducted via Zoom in Spring 2023 (four total). Interviews utilized a Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis approach. Each interview was recorded, transcribed, and validated by study staff for accuracy. Themes from each were inductively coded and then collated across all four sites. Results: The urologists, oncologists, phlebotomists, pathologists, nurses, research coordinators that make up the study teams identified the holistics of conducting the IRONMAN study at their sites. Strengths included a large patient population to recruit from and appropriate resources to conduct the study (ex., lab space, clinical knowledge, staffing levels). Weaknesses included the social determinants of health that negatively impact patient participation, limited biorepository space to store samples, and the need for patient-physician trust. The greatest opportunity presented was Nigerian institutions joining more CTs in the future, particularly multi-site global trials. Described threats included staff turnover, national stability, and increased economic disparities. Discussion: While increasing the overall number of CTs in Africa is a noble cause, sponsors and institutions should note the unique circumstances in implementing CTs in Africa when designing CTs and recruiting sites. Listening to the experiences of study teams is pivotal in ensuring CTs are Africa-minded - they will be complimentary to established research infrastructure, appropriately funded, and culturally responsive all in the name of equitable research. By doing so, ethical compliance and quality data collection will ensue and reduce disparities at the micro, mezzo, and macro levels. Citation Format: Opeyemi Oreoluwa Bolajoko, Parisa Fathi, Oluwaseyi Toye, Dottington D. Fulwood, Ademola Popoola, Chidiebere Ogo, Hassan Dogo, Omolara Fatiregun, Anthonia Sowumi, Paul Jibrin, Mutiu A. Jimoh, Faruk Mohammed, Folakemi Odedina, Prostate Cancer Transatlantic Consortium. Strengths, weaknesses, opportunities, and threats of conducting clinical trials in Nigeria: The IRONMAN study [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 1013.