Alton, Drake

Abstract Introduction Triple-negative breast cancer (TNBC) is an aggressive subtype lacking estrogen (ER), progesterone (PR), and HER2 expression. It accounts for ∼15% of breast cancers and is more common in Black women, younger patients, and those with BRCA1 mutations. TNBC carries a poor prognosis with 5-year survival rates of 92% (localized), 66.8% (regional), and 14.3% (metastatic). Patients with high-risk of recurrence can be treated with different adjuvant therapies based on results of 3 trials (capecitabine, pembrolizumab, olaparib), but data on adverse events (AE) on their combination is limited.High-risk, stage II-III TNBC is treated with curative intent using neoadjuvant chemotherapy with pembrolizumab, followed by surgery and radiation. Pembrolizumab, an anti-PD-1 checkpoint inhibitor, was FDA-approved in 2021 based on KEYNOTE-522. This phase III trial showed that pembrolizumab plus chemotherapy significantly improved pathologic complete response (pCR) and event-free survival (EFS). 3-year EFS was 84.5% vs. 76.8% with placebo (HR 0.63); 5-year follow-up confirmed sustained benefit, with OS of 86.6%. Patients achieving pCR had better outcomes, while those with residual disease remained at high risk for recurrence, justifying further adjuvant therapy.In KEYNOTE-522, grade ≥3 treatment-related (AEs occurred in 77.1% receiving pembrolizumab-chemotherapy vs. 73.3% with placebo-chemotherapy. Pembrolizumab was linked to more serious AEs (34.1% vs. 20.1%) and higher discontinuation rates (23.3% vs. 12.3%). Before pembrolizumab, capecitabine was standard of care for TNBC with residual disease, based on the CREATE-X trial (HR 0.52 for OS benefit). Common AEs included hand-foot syndrome, fatigue, and liver enzyme elevation. Notably, KEYNOTE-522 excluded adjuvant capecitabine, and CREATE-X predated the use of pembrolizumab. Olaparib, a PARP inhibitor, was FDA-approved in 2022 for high-risk early TNBC with germline BRCA mutations, based on OlympiA. It improved invasive disease-free and OS. Grade ≥3 AEs included anemia, neutropenia, and fatigue. OlympiA did not include pembrolizumab or capecitabine, limiting insight into optimal sequencing or combination. Currently, no trials compare pembrolizumab, capecitabine, or olaparib directly, nor do they guide how to sequence or combine these therapies. Despite NCCN guidelines allowing combined/sequential use in high-risk patients, real-world safety and outcome data are lacking. This study aims to evaluate and compare the safety and effectiveness of capecitabine, olaparib, pembrolizumab, and their combinations. We will describe AE rates, onset, discontinuation, and dose modifications to inform clinical management and help reduce early termination of effective therapies. Methods We conducted a retrospective observational study across all Mayo Clinic sites. Eligible patients were ≥18 years with early-stage TNBC who initiated adjuvant therapy with capecitabine, pembrolizumab, olaparib, or combinations (capecitabine + pembrolizumab or olaparib + pembrolizumab) from October 2018 to September 2024. Patients with metastatic disease, other active malignancies, or receiving concurrent investigational therapy were excluded. The primary outcomes were incidence and timing of treatment-related AEs. Secondary outcomes included time to AE resolution, immune-related AEs, treatment interruptions/modifications, early discontinuation, and EFS. Time-to-event data will be analyzed using Kaplan-Meier and Cox proportional hazards models. Subgroup analyses by age, DPYD status, regimen, and dosing will be conducted. Data was abstracted from electronic health records and managed using REDCap. Results Data collection is completed. Final analyses are being conducted, and results will be presented at SABCS 2025. Citation Format: R. Garza-Morales, F. Raheem, D. Alton, S. Sharma, B. Murad, W. Harris, E. Terwilliger, F. Batalini. Analysis of Adverse Events and Outcomes of Adjuvant Therapies in TNBC as Monotherapy and Combination: Pembrolizumab, Capecitabine, and Olaparib [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS4-10-06.

Abstract Glioblastoma (GBM) and Alzheimer’s disease (AD) are devastating, age associated disorders with no cure. Epidemiologic data has established an inverse comorbidity between AD and cancer, including GBM, with up to a 50% reduction of cancer incidence in AD patients. While the underlying biology remains unclear, myeloid cells, which are central players in both neurodegeneration and tumor immunity, may serve as a mechanistic link. We hypothesize that myeloid cells activated by pre-existing AD pathology suppress tumor growth more effectively than homeostatic microglia. In this study, age-matched APPNL-G-F/MAPT double knock-in (henceforth “AD”) and wildtype (WT) mice received orthotopic xenografts of syngeneic GBM cell lines (GL261, SB28) (n=15/sex/genotype). We observed a significant survival difference, with AD mice living an average of 20% longer than WT mice (p<0.0001). In vivo luciferase imaging revealed impaired engraftment of tumor cells in AD mice compared to WT a week post-engraftment (p<0.05). At the microscopic level, tumors in AD mice were found to have nearly 2-fold the amount of tumor-infiltrating myeloid cells (p<0.01), with the proportion of anti-tumoral “activated” myeloid cells also being greater (p<0.05). Tumors in AD mice were found to have markedly higher immune infiltrate at the tumor rim and margin (p<0.001). We also observed striking astrogliosis (GFAP+) and microgliosis (P2RY12+) in both the tumor rim (p<0.05) and margin (p<0.01) in AD animals. This robust glial response was significantly higher in AD mice bearing tumor compared to both WT mice bearing tumor and sham AD mice. Lastly, we utilized a luciferase stain to visualize tumor cells that invaded beyond the bulk tumor. We found that both the quantity (p<0.01) and invasion distance of tumor cells (p<0.05) was lower in AD mice. We demonstrate that an AD-induced inflammatory microenvironment antagonizes glioma growth, providing a foundation for novel GBM treatment strategies that potentially exploit these immune signals.

Abstract Recent studies demonstrate that platelet factor 4 (PF4), an abundant platelet-derived chemokine in young plasma, can reduce neuroinflammation, enhance cognition, and rejuvenate peripheral immunity in aged mice. Intriguingly, neuroimmune markers modulated by PF4—such as Iba1, CD68, and C1q—also contribute to glioma progression. Age-associated immune shifts, including increased myeloid-to-lymphocyte ratios, T cell depletion, and systemic inflammation, are similarly implicated in cancer development. Here, we show that systemic administration of PF4 significantly extends survival in aged (18–23 month-old) glioma-bearing mice and trends toward improved outcomes in young (2–3 month-old) counterparts. Longitudinal IVIS imaging revealed reduced tumor-associated luminescence in PF4-treated animals, particularly in aged males and females. Histological analysis demonstrated downregulation of microglial and macrophage activation markers within the tumor microenvironment. Ongoing studies utilizing flow cytometry, cytokine profiling, and novel PF4-delivery platforms aim to further elucidate its effects on both central and peripheral immunity. These findings suggest that age-related immune modulation may be leveraged to delay glioma progression, positioning PF4 as a promising therapeutic at the intersection of aging, immunology, and neuro-oncology.

1089 Background: T-DXd has become an important treatment option in mBC and other malignancies. Interstitial lung disease/pneumonitis (ILD) occurred in 10-14% of pts in the DESTINY-Breast trials (0-2% G5 ILD), and with potential lower incidence/severity in earlier line settings (Krop et al, ASCO 2023). We previously reported the Mayo Clinic Rochester, MN experience with T-DXd related ILD in mBC (Hoppenworth et al, ASCO 2024). Here, we expand the data to include patients treated at all locations of the Mayo Clinic Enterprise. Methods: We retrospectively identified pts with mBC who received ≥1 dose of T-DXd across the Mayo Clinic enterprise (Rochester, MN; Mayo Clinic Health System locations in MN/WI; Scottsdale, AZ; and Jacksonville, FL) between July 2022-December 2023. Demographic, mBC characteristics, and pulmonary clinical variables were abstracted from the clinical records. Data were summarized using descriptive statistics. Diagnosis of ILD was determined by treating clinicians, and severity was approximated to CTCAE V5 based on clinical documentation. Results: 252 pts with mBC received T-DXd during the study period. The majority were Caucasian (86%) and female (99%) with a median age of 63. 91 pts (36%) were current/formers smokers and 97 (39%) had prior pulmonary comorbidities. The majority had HER2 low (155, 62%) and HR positive (164, 65%) mBC. 35 (14%) developed any grade ILD [G1: 6 (17%), G2: 13 (37%), G3: 3 (8.6%), G4: 3 (8.6%), G5: 10 (29%)], with 15 (43%) presenting with ≥G3. 29 (83%) presented with at least 1 symptom (cough or SOB). Among those with previous pulmonary toxicity, 4 (33%) had previous pneumonitis in the ILD cohort. The median prior lines of all therapies (including endocrine therapy) were 5, with a median of 3 prior lines of chemotherapy in both the ILD (range 1-13) and non-ILD cohorts (range 1-13). Median onset to any grade ILD was 7 cycles. 20 pts (57%) received steroids for ILD. 14 (40%) had a bronchoscopy, all had a CT chest, 16 (46%) were hospitalized, 7 (20%) were intubated and 1 (3%) had a lung biopsy. Pts with G5 ILD had a median of 3 lines of chemo and a median of 8 cycles prior to onset of ILD, compared to 3 lines of chemo and a median of 7 cycles for those with G1-4 ILD. G5 pts were all Caucasian females, 5 were former smokers, 5 were non-smokers, 1 had a history of pneumonitis. T-DXd was rechallenged in 4 pts (G1-2 ILD) without ILD recurrence. Conclusions: In this retrospective case series,14% of pts treated with T-DXd experienced any grade ILD (4% G5) which is in alignment with the rate observed in the pivotal DESTINY-Breast trials, though with higher rates of G5 toxicity. Among those with ILD, increased lines of therapy were not associated with increased risk. Further research is needed to correlate risk.

Abstract Glioblastoma (GBM) and Alzheimer’s disease (AD) are two devastating central nervous system diagnoses with no known cure. Both diseases are associated with advanced age. The majority of GBM tumors form in the frontal and temporal lobes, two of the brain regions most impacted by amyloid and tau pathology in AD. Females have a higher risk of AD, while males have a higher risk of GBM. Several large case series have established epidemiological evidence that the two diseases are inversely correlated. Nevertheless, it remains unknown whether presence of subclinical amyloid or tau pathology antagonizes the establishment or progression of GBM. The present study sought to characterize GBM growth, progression, and immune response in the setting of concomitant AD pathology using the syngeneic murine GL261 tumor model. To further understand the tumor cell changes that occur in the presence or absence of AD pathology, we engineered GL261 with a dual-tagged vector consisting of RiboTag (to allow for full-length mRNA profiling) and TurboID (to allow for proteomic profiling). GL261 cells were injected intracranially into APPNL-G-F/NL-G-F - MAPThuman/human, APPNL-G-F/+ - MAPThuman/+, and wildtype C57BL/6J mice. Tumors in both wildtype and AD conditions contained ~50% intratumoral myeloid cells (Iba+, P2RY12-). Differential activation of intratumoral myeloid cells will be assessed with immunohistochemistry. Microgliosis (IBA1, P2RY12) and astrogliosis (GFAP) around the tumor in the setting of Alzheimer’s pathology versus normal conditions will be compared. Invasiveness, proliferation, DNA damage (pH2AX), and apoptosis (cleaved PARP, cleaved Caspase 3) will be compared. Tumor cell-specific changes unique to tumors in the AD microenvironment will be assessed transcriptionally with RiboTag profiling as well as proteomically with TurboID purifications. Our preliminary data suggests that the presence of concomitant AD pathology affects GBM growth and progression as well as the immune response to the tumor, and warrants further investigation. Citation Format: David Nascari, Ryan Eghlimi, Angad Beniwal, Drake Alton, John Fryer, Nhan L. Tran. Altered tumor microenvironment in animal model of concomitant GBM and Alzheimer's pathology [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 5562.

Abstract Glioblastoma (GBM) is a high grade glioma that accounts for the majority of primary malignant brain tumors. The standard of care for GBM consists of maximal surgical resection, concurrent radiation and temozolomide (TMZ), and adjuvant TMZ. However, this has only led to a modest increase in median patient survival. TROY (TNFRSF19) is an orphan member of the TNF receptor superfamily that is differentially upregulated in GBM with low expression in normal brain tissue. Previously, we have reported that TROY is overexpressed in GBM and signals to mediate cell invasion and therapeutic resistance. Propentofylline (PPF) is a well-studied synthetic methylxanthine derivative that has strong BBB penetrance. We have shown that PPF decreases TROY expression in gliomas, inhibits invasion, and sensitizes GBM to TMZ in vitro. Here we examined the efficacy of PPF in combination with TMZ using in vivo studies of intracranial models of GBM patient-derived xenograft (PDX) models in murine. We tested 3 models of GBM PDX cells with various TROY expression levels (GBM8-high TROY; GBM43-moderate TROY; GBM22-low/no TROY). Our intracranial PDX experiments showed that PPF treatment alone did not increase survival in all PDX cells. The combination of PPF and TMZ treatment did provide a survival benefit (p < 0.039) relative to TMZ alone (only in GBM8-high TROY and GBM43-moderate TROY) that was partially lost when treatment was discontinued. However, continuous PPF administration following a concomitant PPF and TMZ treatment course led to extended survival (p < 0.0015) compared to TMZ alone resulting in increased DNA damage (γH2AX) and apoptotic markers (Cleaved Caspase-3). Immunohistochemical analyses showed that TROY expression was decreased in tumors treated with PPF. In addition, PPF-treated tumors showed a differential myeloid population with well circumscribed tumors as compared to control-treated or TMZ-treated tumors. Thus, our data demonstrates that PPF may provide a pharmacological approach to targeting TROY concomitant with standard-of-care to increase patient survival. Citation Format: Ryan Eghlimi, David Nascari, Angad Beniwal, Drake Alton, Dustin Grief, Joseph Loftus, Melanie Haluska, David Coleman, Nhan Tran. Propentofylline enhances GBM sensitivity to temozolomide via targeting TROY signaling [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 5905.