Trials In Metastatic Breast Cancer Research Articles

Exercise as part of survivorship care in metastatic breast cancer: protocol for the randomized EMBody trial

BackgroundExercise is associated with improved survival, physical functioning, treatment tolerability, and quality of life in early-stage breast cancer. These same endpoints matter in metastatic breast cancer (MBC). Prior trials in MBC have found exercise to be not feasible or of limited benefit, possibly due to inclusion of patients with heterogeneous disease trajectories. Patients with MBC have variable disease trajectories and supportive care needs; those with indolent MBC have longer life expectancy, lower symptom burden and distinct priorities, and are well-positioned to participate in and benefit from an exercise program. The EMBody trial aims to determine the impact of a multimodal exercise intervention on cardiorespiratory fitness, physical function, body composition, and patient-reported outcomes, specifically in patients with stable, indolent MBC.MethodsEligible patients have MBC with no evidence of disease progression on current therapy in the prior 12 months and cannot be receiving cytotoxic chemotherapy. The trial aims to enroll 100 patients, randomized 1:1 to the exercise intervention versus usual care, stratified by baseline function. The virtually-delivered exercise intervention arm achieves moderate intensity exercise with exercise physiologists 3 days/week for 16 weeks. The 60-minute sessions include aerobic, resistance, balance and stretching exercises. The exercise arm receives informational sessions on the role of exercise in cancer and principles of habit and self-efficacy. The primary endpoint is 16 week change in fitness on a ramp treadmill test between the exercise and control arms. Secondary endpoints include change in a physical function, muscle mass assessed by CT scans, and PROs of fatigue and quality of life. Exploratory analysis includes behavioral modifiers of exercise adherence and effectiveness and serologic measures of inflammatory, metabolic, and immune pathway biomarkers.DiscussionThe EMBody trial evaluates exercise in a unique patient population with indolent, non-progressive MBC. Patients living with MBC experience similar symptom burden to those undergoing therapy for early-stage disease and the benefits achieved with exercise could be similarly impactful. This trial will contribute evidence to support expansion of exercise recommendations, among other survivorship care efforts, to those living with metastatic disease. Clinical trial information: NCT05468034.Trial registrationNCT05468034. Date of registration: 7/12/2022.

Opportunities and Challenges in the Development of Antibody-Drug Conjugate for Triple-Negative Breast Cancer: The Diverse Choices and Changing Needs.

Triple-negative breast cancer (TNBC) is a highly heterogeneous breast cancer subtype, which is also characterized by the aggressive phenotype, high recurrence rate, and poor prognosis. Antibody-drug conjugate (ADC) is a monoclonal antibody with a cytotoxic payload connected by a linker. ADC is gaining more and more attention as a targeted anti-cancer agent. Clinical studies of emerging ADC drugs such as sacituzumab govitecan and trastuzumab deruxtecan in patients with metastatic breast cancer (including TNBC) are progressing rapidly. In view of its excellent clinical efficacy and good tolerability, Sacituzumab govitecan gained accelerated approval by the FDA for the treatment of advanced metastatic TNBC in 2020. This review discusses the treatment status and challenges in TNBC, with an emphasis on the current status of ADC development and clinical trials in TNBC and metastatic breast cancer. We also summarize the clinical experience and future exploration directions of ADC development for TNBC patients.

A whole food, plant-based randomized controlled trial in metastatic breast cancer: feasibility, nutrient, and patient-reported outcomes

PurposeQuality of life (QOL) is among the most important outcomes for women with metastatic breast cancer (MBC), and it predicts survival. QOL is negatively impacted by cognitive impairment, fatigue, and weight gain. We assessed whether a whole food, plant-based (WFPB) diet-promoting weight loss is feasible and might improve QOL.MethodsWomen with MBC on stable systemic treatments were randomized 2:1 to 1) WFPB dietary intervention (n = 21) or 2) usual care (n = 11) for 8 weeks. Participants attended weekly education visits and consumed an ad libitum WFPB diet (3 prepared meals/day provided). Patient-reported outcomes and 3-day food records were assessed at baseline and 8 weeks. The effects of WFPB diet on changes in outcomes were assessed by analysis of covariance model controlling for baseline.Results20 intervention and 10 control participants completed the trial. Intervention participants were highly adherent to the WFPB diet (94.3 % total calories on-plan). Intervention group nutrient intakes changed significantly including dietary fat (35.8 % to 20.4 % percent calories from fat, p < 0.001) and fiber content (12.7 to 30.8 g fiber/1000 kcal, p < 0.001). Perceived cognitive function (FACT-Cog total + 16.1; 95 % confidence interval [CI] = 0.8–31.7; p = 0.040) and emotional well-being (FACT-B emotional well-being subscale + 2.3; CI = 0.5–4.1; p = 0.016) improved in the WFPB versus the control group. Fatigue, measured by the BFI, improved within the WFPB group for fatigue severity (M = 4.7 ± 2.5[SD] to 3.7 ± 2.3, p = 0.047) and fatigue at its worst (5.8 ± 2.8 to 4.4 ± 2.4, p = 0.011).ConclusionsSignificant dietary changes in this population are feasible and may improve QOL by improving treatment-related symptoms. Additional study is warranted.Trial Registration: ClinicalTrials.gov identifier: NCT03045289. Registered 7 February 2017.

Abstract 6351: MUC1*-ADCs are effective against heterogeneous solid tumor cancers

Abstract Purpose: To develop a MUC1*-ADC for the treatment of over 75% of solid tumor cancers. Methods: MUC1* (muk 1 star) is a growth factor receptor created after cleavage and release of the N-terminal portion of MUC1. The targeting antibody, huMNC2, has already demonstrated safety and cancer selectivity in a 1st-in-human CAR-T clinical trial for treatment of metastatic breast cancers. MNC2 is an IgG1 antibody that only recognizes the conformational epitope created when MUC1 is cleaved by specific tumor-associated enzymes. Confocal microscopy and pHlourin2 were employed to measure antibody internalization as a function of time. We conjugated MNC2 to MMAE, MMAF, Dxd and exatecan via several different linkers. MUC1*-ADCs with DARs ranging from 4-8 were tested in vitro and in vivo for efficacy against a panel of solid tumor cancers. Heterogenous MUC1* tumors were made by mixing different ratios of mCherry wild-type cancer cells with GFP MUC1* overexpressed cancer cells. Resulting H scores ranged from 10-280 (max 300). Results: Cancer cells internalized the MUC1* MNC2 antibody within 2 hours. In vitro, MUC1*-ADC IC50s ranged from 1.3nM to 20.0nM, depending on the linker-payload and cancer subtype, wherein the majority had an IC50 of about 10nM. In general, efficacy in animals was seen across multiple cancer sub-types treated with multiple MUC1*-ADCs. Efficacy in animals xenografted with heterogeneous MUC1* tumors showed a dependence on antigen density. Greatest efficacy was observed for breast cancer xenografts with an H Score &amp;gt;10 treated with MNC2-Deruxtecan. However, only pancreatic tumors with higher H Scores were completely eliminated by MNC2-MMAE, MNC2-Deruxtecan and MNC2-exatecan. MNC2-ADC and MNC2-CAR share the same antibody. No off-tumor toxicity was observed in animals treated with MNC2-ADC, which mimicked lack of off-target toxicities for MNC2-CAR T cells in humans. Conclusions: These data, combined with MNC2-CAR T data from our 1st-in-human trial for metastatic breast cancer, supports a conclusion that the MUC1* antibody MNC2 is safe and could have high therapeutic value as a MUC1*-ADC for multiple solid tumors with both high and low antigen density. Citation Format: Cynthia Carol Bamdad, Benoit S. Smagghe, Scott T. Moe, Mark G. Carter, Trevor J. Grant, Kevin R. Yi, Michael J. Nash, Jacy P. Marquez, Natalie K. Miller, Jac-Leen S. Nash, Dan S. Miller, Danica M. Walkley, Andrew K. Stewart. MUC1*-ADCs are effective against heterogeneous solid tumor cancers [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 6351.

A whole-food, plant-based randomized controlled trial in metastatic breast cancer: weight, cardiometabolic, and hormonal outcomes

PurposeBreast cancer treatment is associated with weight gain, and obesity and its related cardiometabolic and hormonal risk factors have been associated with poorer outcomes. Dietary intervention may address these risk factors, but limited research has been done in the setting of metastatic breast cancer requiring systemic therapy.MethodsWomen with metastatic breast cancer on stable treatment were randomized 2:1 to an 8-week intervention (n = 21) or control (n = 11). The intervention included weekly assessment visits and an ad libitum whole-food, plant-based (WFPB) diet with provided meals. Cardiometabolic, hormonal, and cancer markers were assessed at baseline, 4 weeks, and 8 weeks.ResultsWithin the intervention group, mean weight decreased by 6.6% (p < 0.01) after 8 weeks. Fasting insulin decreased from 16.8 uIU/L to 11.2 uIU/L (p < 0.01), concurrent with significantly reduced insulin resistance. Total cholesterol decreased from 193.6 mg/dL to 159 mg/dL (p < 0.01), and low-density lipoprotein (LDL) cholesterol decreased from 104.6 mg/dL to 82.2 mg/dL (p < 0.01). Total testosterone was unchanged, but free testosterone trended lower within the intervention group (p = 0.08) as sex hormone binding globulin increased from 74.3 nmol/L to 98.2 nmol/L (p < 0.01). There were no significant differences in cancer progression markers at week 8, although mean CA 15-3, CA 27.29, and CEA were lower in the intervention group (p = 0.53, p = 0.23, and p = 0.54, respectively) compared to control, when adjusted for baseline.ConclusionWFPB dietary changes during treatment for metastatic breast cancer are well tolerated and significantly improve weight, cardiometabolic and hormonal parameters. Longer studies are warranted to assess the durability of changes.Trial registration First registered at Clinicaltrials.gov (NCT03045289) on February 7, 2017.

Final Results From the Randomized Phase III ASCENT Clinical Trial in Metastatic Triple-Negative Breast Cancer and Association of Outcomes by Human Epidermal Growth Factor Receptor 2 and Trophoblast Cell Surface Antigen 2 Expression.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Sacituzumab govitecan (SG), a first-in-class anti-trophoblast cell surface antigen 2 (Trop-2) antibody-drug conjugate, demonstrated superior efficacy over single-agent chemotherapy (treatment of physician's choice [TPC]) in patients with metastatic triple-negative breast cancer (mTNBC) in the international, multicenter, phase III ASCENT study.Patients were randomly assigned 1:1 to receive SG or TPC until unacceptable toxicity/progression. Final efficacy secondary end point analyses and post hoc analyses of outcomes stratified by Trop-2 expression and human epidermal growth factor receptor 2 status are reported. Updated safety analyses are provided.In this final analysis, SG (n = 267) improved median progression-free survival (PFS; 4.8 v 1.7 months; hazard ratio (HR), 0.41 [95% CI, 0.33 to 0.52]) and median overall survival (OS; 11.8 v 6.9 months; HR, 0.51 [95% CI, 0.42 to 0.63]) over TPC (n = 262). SG improved PFS over TPC in each Trop-2 expression quartile (n = 168); a trend was observed for improved OS across quartiles. Overall, SG had a manageable safety profile, with ≤5% of treatment-related discontinuations because of adverse events and no treatment-related deaths. The safety profile was consistent across all subgroups.These data confirm the clinical benefit of SG over chemotherapy, reinforcing SG as an effective treatment option in patients with mTNBC in the second line or later.

Therapeutic targeting of p90 ribosomal S6 kinase.

The Serine/Threonine protein kinase family, p90 ribosomal S6 kinases (RSK) are downstream effectors of extracellular signal regulated kinase 1/2 (ERK1/2) and are activated in response to tyrosine kinase receptor or G-protein coupled receptor signaling. RSK contains two distinct kinase domains, an N-terminal kinase (NTKD) and a C-terminal kinase (CTKD). The sole function of the CTKD is to aid in the activation of the NTKD, which is responsible for substrate phosphorylation. RSK regulates various homeostatic processes including those involved in transcription, translation and ribosome biogenesis, proliferation and survival, cytoskeleton, nutrient sensing, excitation and inflammation. RSK also acts as a major negative regulator of ERK1/2 signaling. RSK is associated with numerous cancers and has been primarily studied in the context of transformation and metastasis. The development of specific RSK inhibitors as cancer therapeutics has lagged behind that of other members of the mitogen-activated protein kinase signaling pathway. Importantly, a pan-RSK inhibitor, PMD-026, is currently in phase I/1b clinical trials for metastatic breast cancer. However, there are four members of the RSK family, which have overlapping and distinct functions that can vary in a tissue specific manner. Thus, a problem for transitioning a RSK inhibitor to the clinic may be the necessity to develop isoform specific inhibitors, which will be challenging as the NTKDs are very similar to each other. CTKD inhibitors have limited use as therapeutics as they are not able to inhibit the activity of the NTKD but could be used in the development of proteolysis-targeting chimeras.

Progression-free survival assessment by local investigators versus blinded independent central review in randomized clinical trials in metastatic breast cancer: A systematic review and meta-analysis

IntroductionIn randomized clinical trials (RCTs), blinded independent central review (BICR) is used to minimize heterogeneity and bias associated with radiological response evaluation by local investigators. However, BICR adds costs and complexity to the trial management. We assessed the discrepancy index between progression-free survival (PFS) assessment by local investigators and by BICR in RCTs conducted in patients with metastatic breast cancer (MBC). MethodsA systematic search of PubMed, Embase, Cochrane databases and conference proceedings (ASCO, SABCS, ESMO) was performed up to January 4, 2023 (PROSPERO: CRD42021229865). All RCTs published from 2000 to 2022, including MBC patients treated in first- or second-line, and reporting PFS assessed by local investigators and BICR were included. A discrepancy index between BICR-assessed and investigator-assessed HR was calculated for each trial and an overall combined DI was obtained using a fixed-effects model. The agreement between hazard ratios (HR) of PFS assessed by local investigators and BICR was measured using intraclass correlation coefficient (ICC). ResultsWe analyzed 24 studies including 13,168 patients. Among them, 19 (79%) were in first-line, 18 (75%) were phase III trials and 23 (96%) had PFS as primary endpoint. The overall combined discrepancy index was 0.97 (95%CI 0.85–1.10; ICC 0.831, p < 0.001) suggesting no statistically significant difference in PFS assessment between local investigators and BICR. This result was consistent across all analyzed subgroups. ConclusionsThe good concordance between local investigator and BICR assessments supports the reliability of local investigator-assessed PFS as primary endpoint for RCTs in MBC and questions the practical utility of implementing BICR in all RCTs.

RSK1 Is an Exploitable Dependency in Myeloid Malignancies

Myeloid malignancies harbor distinct molecular drivers but share convergence of oncogenic signaling pathways and propagation by ripe pro-inflammatory niches. To delineate these hallmarks across the spectrum of myeloid disease states, we established the largest comprehensive atlas of myeloproliferative neoplasms (MPN) and secondary acute myeloid leukemia (sAML) through RNA-sequencing and mass cytometry (CyTOF) of 370 primary samples encompassing CD34+ hematopoietic stem/progenitor cells and CD14+ monocytes, revealing aberrant of PI3K/AKT/mTOR signalling and NFκB-mediated hyper-inflammation. As a central mediator of these hyperactive signaling pathways, ribosomal S6 kinases (RSKs) represent potentially attractive novel therapeutic targets warranting further evaluation. Using both genetic approaches and a first-in-class oral RSK inhibitor, PMD-026, that is currently being evaluated in phase 1/1b clinical trials (NCT04115306) in metastatic and triple negative breast cancer, we found that RSK1 ( RPS6KA1) inhibition potently induced apoptosis and G2/M arrest in leukemia models in conjunction with suppression of PI3K/AKT/mTOR and NFκB signaling. Further NFκB cascade profiling following RSK1 perturbation revealed reduced phosphorylation of IKKα/β and p65/RELA and prevention of p65/RELA nuclear translocation. Using RNA-seq, ATAC-seq and H3K27ac CUT&amp;Tag, we found that PMD-026 treatment altered chromatin accessibility and inhibited NFKB1, TNF, and cell cycle regulators CCNA1/2 and CDK1/2. In cytokine CyTOF, PMD-026 nearly abrogated all induction of inflammatory cytokines including TNF, IL-6, IL-8, CCL3, and CCL4 in primary MPN monocytes to levels substantially below basal conditions. We further extended our findings to de novo AML harboring FLT3 internal tandem duplication ( FLT3-ITD), where FLT3-ITD patients exhibited elevated RPS6KA1 expression and those who developed resistance to gilteritinib demonstrated progressively increased RPS6KA1 expression. FLT3-ITD cells exhibited preferentially sensitivity to RSK1 inhibition, where we uncovered bi-directional regulation. Through cycloheximide, MG-132, and ubiquitination assays, we found that RSK1 regulates FLT3-ITD activity and protein stability through deubiqutinase USP1, and where either RPS6KA1 or USP1 inhibition resulted in concomitant downregulation of FLT3 protein and cell lethality. Multivariate analysis of the TCGA and BeatAML cohorts (n= 568 patients) revealed high median USP1 or RPS6KA1 expression to be significantly associated with poor survival, thus defining a RSK1-USP1-FLT3 axis with prognostic relevance. Across in vivo models, PMD-026 ameliorated MPN disease features driven by MPL W515L including leukocytosis, splenomegaly, and bone marrow fibrosis, while prolonging survival, in conjunction with suppression of inflammatory cytokines including TNF, IL-6 and IL-1b. We then evaluated PMD-026 across five patient-derived xenograft (PDX) models spanning the spectrum of myeloid malignancies including myelofibrosis (MF), sAML, and chronic myelomonocytic leukemia (CMML) encompassing various driver and multiple high-risk mutations. Treatment in MF PDX mice decelerated disease progression, extended survival, and reduced splenomegaly, while in CMML/sAML PDXs, PMD-026 led to a 67 to 96 percent reduction in human CD45+ cells engraftment. Finally, PMD-026 treatment in both mice xenografted with MV4-11 cells and syngeneic Flt3ITDTet2KO mice significantly reduced leukemic cell engraftment and prolonged survival. These data indicate potent efficacy of RSK inhibition across diverse models of chronic and acute myeloid malignancies. Lastly, we investigated the impact of PMD-026 on hematological parameters from 41 breast cancer patients enrolled in the phase 1/1b clinical trial. Overall, there was no sustained suppressive effect on hematological parameters and there were no hematological PMD-026-related toxicities meeting criteria for dose modification during the trial period. These clinical data demonstrate that PMD-026 did not cause myelosuppression. Our findings uncover a novel therapeutic avenue for a conserved RSK1 dependency across chronic and acute myeloid neoplasms. The potent and consistent disease-ameliorating effects across numerous leukemia mouse models demonstrates promise for repurposing PMD-026 for the treatment of myeloid malignancies.

459P Progression-free survival (PFS) assessment by local investigators versus blinded independent central review (BICR) in randomized clinical trials (RCTs) in metastatic breast cancer (MBC): Is it really needed?

459P Progression-free survival (PFS) assessment by local investigators versus blinded independent central review (BICR) in randomized clinical trials (RCTs) in metastatic breast cancer (MBC): Is it really needed?

Abstract 1789: Pre-clinical studies to advance anti-ROR1 CAR-T cell therapy for metastatic prostate cancer

Abstract Background: Alterations in WNT signaling are frequently associated with tumorigenesis and metastasis in many cancers including prostate cancer (PCa). The Wnt ligand, WNT5A, is required for normal prostate gland development and is increased in bone metastatic, castration resistant PCa (CRPC) patients. WNT5A signaling is mediated in part through ROR1, a non-canonical Wnt receptor and fetal oncoprotein for which the therapeutic inhibitory antibody, Zilovertamab, has been developed. Its safety has been clinically proven in trials for chronic lymphocytic leukemia (CLL) and metastatic breast cancer. We sought to investigate Zilovertamab-based anti-ROR1 therapies for metastatic prostate cancer.Our Hypothesis is that WNT5A may activate a stem-cell-like program via ROR1 which leads to therapy resistance in metastatic prostate cancer. The anti-ROR1 biologic, Zilovertamab, may inhibit this mechanism of resistance. The expression of ROR1 on CRPC and NEPC tumors and its lack of expression on normal adult tissues makes it a promising CART cell target. Methods: We used the patient-derived xenograft (PDX), PCSD13, small cell bone metastatic prostate cancer model and the neuroendocrine PCa cell lines, PC3 and DU145, to test the effect of Zilovertamab and Zilovertamab-CART cells in vitro using the real time cell viability, proliferation, and cell cycle tracking assays in an Incucyte S3. We used in vivo bioluminescence and tumor caliper measurements to monitor effects in vivo. Results: Studies using RNASeq, qRT-PCR, FACS and Westerns showed high expression of ROR1 in PC3, DU145, and in PCSD13. CRISPR-Cas9 Knock out of ROR1 in PC3 and DU145 cells showed increased inhibition of proliferation at lower docetaxel concentrations. Treatment of PCSD13 PDX in vivo with Zilovertamab increased docetaxel-mediated tumor growth inhibition. Mice bearing PC3 xenografts injected intravenously with Zilovertamab anti-ROR1 CAR-T cells showed durable, tumor ablation in 67% of mice compared to 22% of mice injected with activated T cells from the same donor and 0% of untreated mice. Survival of mice at Day 70 injected with CART was 78% compared to 0% of mice injected with control donor T cells and 0% of untreated mice. Zilovertamab antibody could inhibit Zilovertamab CART cell tumor cell killing. Conclusions: ROR1 was expressed at high levels on castration resistant small cell PCa and neuroendocrine PCa cell lines and PDX models. Zilovertamab synergized with docetaxel to inhibit tumor growth in patient derived xenograft in vivo and in organoid cultures. Zilovertamab-based CART cells durably eradicated ROR1+ prostate cancer xenograft tumors. These studies supported the recently launched Phase 1b clinical trial of Zilovertamab plus docetaxel in metastatic CRPC patients. Clinical development of GMP Zilovertamab CART cells for a clinical trial in CLL is in progress and may lead to rapid progression to a clinical trial for metastatic CRPC and NEPC. Citation Format: Christina A.M. Jamieson, Jamillah Murtadha, Christopher S. Oh, Michelle Muldong, Evodie Koutouan, JOngwook Kim, Niloofar Etemadfard, Hae Soo Choo, Navyaa Sinha, Sanghee Lee, Christina Wu, Gabriel Pineda, Kathleen Lennon, Karl Willert, Catriona H. Jamieson, Terry Gaasterland, Rana Mckay, Christopher J. Kane, Thomas J. Kipps, Anna A. Kulidjian, Nicholas A. Cacalano, Charles Prussak. Pre-clinical studies to advance anti-ROR1 CAR-T cell therapy for metastatic prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1789.

PD04-10 PRE-CLINICAL STUDIES TO ADVANCE ZILOVERTAMAB-BASED ANTI-ROR1 DUAL SPECIFICITY CAR T-CELL THERAPY FOR METASTATIC PROSTATE CANCER.

PD04-10 PRE-CLINICAL STUDIES TO ADVANCE ZILOVERTAMAB-BASED ANTI-ROR1 DUAL SPECIFICITY CAR T-CELL THERAPY FOR METASTATIC PROSTATE CANCER.

Abstract P5-07-08: Evaluating the risk of cardiotoxicity associated with concurrent trastuzumab emtansine (TDM1) and radiation therapy in patients with early-stage HER2 positive breast cancer

Abstract BACKGROUND: HER2-positive breast cancers, which accounts for 20% of breast cancers, is associated with aggressive clinical behavior and inferior survival. The approval of HER2 targeted therapy has changed the landscape of this disease and has reduced disease recurrence by 50% and has improved survival by 33%. (1) However, cardiotoxicity is a well-recognized adverse event associated with HER2-targeted therapies. Adjuvant trastuzumab emtansine (TDM1) is the current standard of care for patients with residual breast cancer after neoadjuvant HER2-targeted therapy. TDM1 is associated with a risk of cardiotoxicity defined as a decline in left ventricular ejection fraction (LVEF). In a pooled analysis of data from seven metastatic breast cancer trials with TDM1, the incidence of cardiac events such as congestive heart failure (CHF), cardiac ischemia, cardiac arrhythmia or grade 1/2 LVEF drop was 3.37%. Adjuvant breast radiation (RT) is routinely offered for patients at high risk for recurrence. Breast RT is also associated with long-term increased risk of cardiac disease more than 10 years after RT. The HERA trial which studied use of adjuvant trastuzumab showed that rates of cardiotoxicity were higher in patients receiving concurrent RT with trastuzumab (left sided &amp;gt; right sided breast cancer) compared to those who did not receive adjuvant RT, although not statistically significant. In the multivariate analysis, no treatment or baseline cardiovascular risk factors were strongly correlated with LVEF, but radiation therapy showed a borderline correlation (adjusted HR, 1.258; 95% CI, 1.00-1.58; P = .049). The risk of cardiotoxicity with concurrent TDM1 and RT has not been well studied. With increasing use of TDM1 in the adjuvant setting, it is important to understand the cardiotoxic effects of combination therapy in early-stage breast cancer. METHODS: We undertook a review of our clinical database to identify patients who received adjuvant TDM1 with concurrent RT for Stage I-III breast cancer from 1/2020 to 01/2022. Clinical parameters including age, date of diagnosis, history of cardiac disorders, echocardiogram findings, radiation dose, final pathologic stage and molecular subtypes of cancer were extracted. All patients had ejection fraction to monitor cardiac fraction. Global longitudinal strain (GLS), which is a more sensitive and reproducible indicator of cardiac dysfunction than LVEF, was also collected, if available. RESULTS: Of 32 patients identified in our retrospective analysis, two patients (6%) developed a drop in ejection fraction post radiation. Median age of patients was 57y. Majority of the patients were Caucasian (44%) followed by Hispanic (28%). 19 (60%) patients had right sided breast cancers and 13(40%) patients had left sided cancers. The mean pre-radiation ejection fraction was 60% and post radiation was 61%. Using paired t-testing, there was no statically significant difference in ejection fraction after radiation (p=0.343). Comparative GLS measurements were available for 16 patients and there was no statical difference with concurrent radiation (p=0.18). All patients tolerated radiation with mostly grade 2 skin dermatitis except four patients who had grade 3 skin dermatitis. One patient had to discontinue radiation early given grade 3 skin dermatitis. CONCLUSION: This institutional review of 32 patients suggests that adjuvant TDM1 with concurrent RT did not result in a significant change in ejection fraction or GLS. Most patients tolerated radiation without significant skin toxicities. One of the limitations of the study is the small sample size. A larger study should look at more broader conclusions; however this data has strong clinical implications. Cardiac Parameters pre and post RT Citation Format: Faheem Farooq, Dillon Cason, Nisha Ohri, Shicha Kumar, Allison Grann, Anna Litvak, Shridar Ganesan, Bruce G. Haffty, Deborah Toppmeyer, Coral Omene, Mridula A. George. Evaluating the risk of cardiotoxicity associated with concurrent trastuzumab emtansine (TDM1) and radiation therapy in patients with early-stage HER2 positive breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-07-08.

Abstract P6-10-11: Engineered neoantigen-specific T cell receptors to treat metastatic breast cancer

Abstract T cell receptor engineered T cell (TCR T) therapy has emerged as a promising therapeutic modality for solid cancer following recent trials demonstrating the safety and efficacy of TCR T therapies against some types of metastatic solid cancers. However, the broader application of TCR T towards many solid tumors, including metastatic breast cancer (MBC), has been limited by several factors, chiefly among them the current scarcity of tumor selective target antigens. Neoantigens, which are expressed exclusively in cancer cells, are currently underrepresented in TCR T development, being targeted in only about 7% of trials conducted to date, and thus represent a relatively untapped source of potentially safe and effective novel targets. Driver mutations in AKT1, ESR1, PIK3CA, and TP53 are common in patients with MBC, and could serve as ideal neoantigen targets for TCR T therapies. We hypothesized that we could generate MBC driver mutation-specific T cells from which we could isolate and clone neoantigen-specific TCRs to generate TCR T products for MBC. We identified 13 driver missense mutations that are among the most frequent in patients with MBC, which included AKT1 (E17K), ESR1 (K303R, Y537S, D538G), PIK3CA (E542K, E545K, H1047L, H1047R), and TP53 (R175H, R248Q, R248W, R273C, R273H), then designed peptide libraries consisting of 15-mer overlapping peptides that contain these mutations. To determine if these neopeptides could elicit T cell responses, we isolated T cells from 15 healthy donors and 11 MBC patients who expressed at least one of the targeted mutations and performed successive stimulations with neopeptide pulsed dendritic cells, then screened the resulting T cell lines for neoantigen specificity using an IFN-γ ELISpot assay. We observed neopeptide T cell responses in 8/16 lines generated from healthy donors and 7/11 lines generated from MBC patients, which were collectively directed against 11/13 of the targeted driver mutations. To isolate neoantigen-specific TCRs from one of these lines, we performed IFN-γ capture, limiting dilution, and 5’ RACE, and isolated an HLA-B*35 restricted TP53 R248W-specifc TCR. Gene transfer of this TCR conferred edited T cells with potent activity towards the TP53 R248W and not the TP53 WT peptide as assessed by ELISpot (1036 vs 46 SFU/1 × 105 cells, respectively) and chromium release cytoxicity assay targeting peptide pulsed autologous PHA blasts (37.5% vs 0% lysis at E:T 40:1, respectively). To increase the throughput of TCR discovery, we next used a single cell RNA sequencing based TCR discovery approach whereby we stimulated T cells from one of the generated lines with ESR1 WT or neopeptide and identified responsive T cell clones through upregulation of IFN-γ and/or TNF-α. This strategy has so far enabled us to identify and validate two ESR1 mutant-specific TCRs. This includes an HLA-C*01 restricted TCR that confers edited T cells with dual activity towards both ESR1 Y537S and D538G, but not WT peptide as determined by both ELISpot (2094, 3194, and 79 SFU, respectively) and chromium release cytotoxicity (31.3%, 77.8%, and 9.1% lysis, respectively), as well as an HLA-B*40 restricted TCR that confers high ESR1 Y537S specificity (5039 vs 138 SFU in response to ESR1 Y537S vs WT peptide, respectively). In summary, we have demonstrated responses of T cells derived from both healthy donors and MBC patients towards neopeptides derived from common MBC driver mutations. We have so far isolated neoantigen specific TCRs from two of the neoantigen-specific T cells lines, including TCRs specific towards TP53 R248W, ESR1 Y537S, dual ESR1 Y537S+D538G that are restricted to three different HLA alleles, and have successfully used these TCRs to generate TCR T products with high neoantigen activity. These results encourage further efforts to identify TCRs recognizing these MBC driver mutations, with our ultimate aim to translate neoantigen-targeted TCR T therapies to clinical trials of MBC. Citation Format: Paul Shafer, Wingchi K. Leung, Mae L. Woods, Carlos Rodriguez-Plata, Arushana Ali, Saisha Nalawade, Lauren M. Kelley, Jarrett Joubert, Anthony Manliguez, Spyridoula Vasileiou, Suzanne A. Fuqua, Premal Lulla, Cliona Rooney, Ann Leen, Valentina Hoyos. Engineered neoantigen-specific T cell receptors to treat metastatic breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-10-11.

New treatment options for metastatic HER2-low breast cancer : Consequences for histopathological diagnosis.

The overexpression of HER2 in breast cancer is aclassic example for molecular targeted therapy, and it has been shown that classical anti-HER2 therapeutics were only effective in patients with HER2 overexpressing tumors. Therefore, in recent decades, pathologists have been focused on the reliable identification of HER2 overexpressing tumors. Based on the results of recent clinical trials in metastatic breast cancer with antibody-drug conjugates (ADCs), this diagnostic strategy for evaluation of HER2 is currently changing. It has been shown that the ADC trastuzumab-deruxtecan is effective not only against tumors with classical HER2 overexpression, but also against HER2-low tumors. These clinical trial results lead to aparadigm shift in the treatment of patients whose tumours were previously classified as HER2 negative. In addition to the identification of HER2 (score3+) overexpressing tumors, it is necessary to identify HER2-low expressing tumors (defined as an immunohistochemistry (IHC) score of1+ or IHC2+ with negative in situ hybridization).Due to the therapeutic consequences, it is important to quickly adapt the diagnostic workup and reporting to the new requirements. In addition, the new therapeutic options for anti-HER2 therapy lead to new challenges for standardization as well as to new scientific questions for the characterization of tumors with low HER2 expression.

New treatment options for metastatic HER2-low breast cancer : Consequences for histopathological diagnosis

Die standardisierte HER2-Bestimmung beim Mammakarzinom und bei anderen Tumoren ist eine wichtige Aufgabe der Pathologie. Ziel der bisherigen Bestimmung war es, zuverlässig diejenigen Tumoren zu identifizieren, die eine Überexpression des HER2-Proteins aufweisen, die in der Regel mit einer Genamplifikation einhergeht. Nur in dieser Gruppe von Tumoren war eine zielgerichtete Anti-HER2-Therapie sinnvoll und erfolgversprechend. Durch neue Substanzen und die Ergebnisse klinischer Studien beim metastasierten Mammakarzinom hat sich dies nun geändert. Es konnte gezeigt werden, dass Trastuzumab-Deruxtecan, ein Konjugat aus einem Anti-HER2-Antikörper und einer zytotoxischen Substanz, auch dann einen Anti-Tumor-Effekt aufweist, wenn nur eine geringe Expression von HER2 im Tumorgewebe vorliegt.Die aktuellen Daten bedeuten einen Paradigmenwechsel für die Behandlung von Patientinnen, deren Tumoren bislang als HER2-negativ eingeordnet wurden. Ziel ist es jetzt, neben den Tumoren mit einer HER2-Überexpression (IHC 3+) auch die Tumoren mit einer geringen HER2-Expression (HER2-low, definiert als IHC 1+ oder 2+/ISH-negativ) zuverlässig zu identifizieren. Aufgrund der therapeutischen Konsequenzen ist es wichtig, die diagnostischen Algorithmen und Befundtexte in allen pathologischen Instituten sehr kurzfristig an die neuen Erfordernisse anzupassen. Unabhängig davon ergeben sich neue wissenschaftliche Fragen und Herausforderungen für die Standardisierung, die aktuell bearbeitet werden.

Augmenting control arms with real-world data for cancer trials: Hybrid control arm methods and considerations

BackgroundHybrid controlled trials with real-world data (RWD), where the control arm is composed of both trial and real-world patients, could facilitate research when the feasibility of randomized controlled trials (RCTs) is challenging and single-arm trials would provide insufficient information. MethodsWe propose a frequentist two-step borrowing method to construct hybrid control arms. We use parameters informed by a completed randomized trial in metastatic triple-negative breast cancer to simulate the operating characteristics of dynamic and static borrowing methods, highlighting key trade-offs and analytic decisions in the design of hybrid studies. ResultsSimulated data were generated under varying residual-bias assumptions (no bias: HRRWD = 1) and experimental treatment effects (target trial scenario: HRExp = 0.78). Under the target scenario with no residual bias, all borrowing methods achieved the desired 88% power, an improvement over the reference model (74% power) that does not borrow information externally. The effective number of external events tended to decrease with higher bias between RWD and RCT (i.e. HRRWD away from 1), and with weaker experimental treatment effects (i.e. HRExp closer to 1). All dynamic borrowing methods illustrated (but not the static power prior) cap the maximum Type 1 error over the residual-bias range considered. Our two-step model achieved comparable results for power, type 1 error, and effective number of external events borrowed compared to other borrowing methodologies. ConclusionBy pairing high-quality external data with rigorous simulations, researchers have the potential to design hybrid controlled trials that better meet the needs of patients and drug development.

New era for emerging therapeutic targeting human epidermal growth factor receptor 3 (HER 3) in advanced nonsmall cell lung cancer and metastatic breast cancer

AbstractHuman epidermal growth factor receptor 3 (HER3) is a member of the transmembrane receptor tyrosine kinase family. Upregulation of HER3 pathway has been implicated as a mechanism of resistance in solid tumors, particularly in estrogen receptor positive, HER2 positive breast cancer and epidermal growth factor (EGFR) mutant nonsmall cell lung cancer. Several studies suggest that HER3 overexpression represents a negative prognostic biomarker associated with poor survival. Preclinical and clinical studies of anti‐HER3 investigational therapies suggest that expression of the HER3 ligand, neuregulin, may predict response to treatment. Despite its emergence as a key cancer therapeutic target, HER3 cannot be targeted with traditional tyrosine kinase inhibitors therapy due to its weak kinase activity. Monoclonal and bispecific antibodies targeting HER3 have been developed and tested in early phase trials. Objective responses were limited when first‐generation HER3‐specific monoclonal antibodies were investigated as monotherapies in phase 1 and 2 clinical trials for nonsmall cell lung cancer (NSCLC) and metastatic breast cancer (MBC). MBC and NSCLC HER3 specific antibody‐drug conjugates have shown encouraging results in resistance in cancer cells, particularly in those that overexpress HER3. These agents have shown some promise in early phase trials in both NSCLC and MBC setting in heavily pretreated patients with varying degrees of response. It is unclear which subgroup of patients will truly benefit from targeting HER3 as these therapies are under investigation.

Abstract 1118: The novel rexinoid V-125 reduces tumor growth in the MMTV-Neu model of breast cancer and the A/J model of lung cancer via immunomodulation

Abstract Rexinoids are ligands which selectively bind to and activate Retinoid X Receptors (RXRs), regulating the transcription of genes involved in several cancer-relevant biological processes. Rexinoids have anti-neoplastic activity with low toxicities in multiple preclinical studies. Bexarotene, used to treat cutaneous T cell lymphoma, is the only FDA-approved rexinoid. Bexarotene has also been evaluated in clinical trials for metastatic breast cancer and non-small-cell lung carcinoma. Subsets of patients in these trials exhibited clinical responses despite advanced, late-stage disease and refractoriness to prior therapy. By modifying structures of known efficacious rexinoids, we can improve potency, increase selectivity for RXR, and minimize toxicity. We have screened a series of novel rexinoids, which are selective for RXR with minimal off-target activation. V-125 was selected as our lead based on its performance in an optimized in vitro screening paradigm. V-125 displayed potent anti-inflammatory activity without elevating triglycerides, a known adverse effect of other rexinoids. To validate our screening paradigm, the tumor-preventive effects of V-125 were assessed in two clinically relevant mouse models: the MMTV-Neu model of HER2+ breast cancer and the A/J model of lung carcinogenesis. V-125 significantly (p &amp;lt; 0.001) increased tumor-free survival of MMTV-Neu mice in comparison to controls, resulting in a ~10 week increase in mean time to tumor development. In A/J mice, V-125 significantly (p &amp;lt; 0.05) reduced lung surface tumor number, size, and burden without increasing plasma triglycerides. To assess the treatment efficacy of V-125, MMTV-neu mice with established tumors were treated with V-125 or control diet. Overall survival was significantly (p &amp;lt; 0.05) higher in mice treated with V-125 than the control. To characterize the mechanism of V-125, we evaluated a mouse breast cancer PCR array, which demonstrated that V-125 downregulates IL-6 mRNA expression in MMTV-Neu tumors over three-fold, suggesting that V-125 modulates crosstalk between cancer cells and immune cells. We have previously shown that rexinoids alter immune cell populations in tumors and modulate secretion of inflammatory cytokines. A growing body of literature also suggests that RXR plays a role in regulating phenotype and function of macrophages. To test the hypothesis that V-125 modulates macrophage populations in the tumor microenvironment, we evaluated the ability of V-125 to differentially skew tumor-educated macrophages. Bone marrow-derived macrophages were stimulated with conditioned media from MMTV-Neu tumor cells and treated with V-125, and the expression of phenotypic markers was assessed by qPCR. These studies provide insight into the mechanism of V-125, which has the potential to be effective in reducing cancer growth. Citation Format: Lyndsey Reich, Jessica Moerland, Ana S. Leal, Di Zhang, Sarah Carapellucci, Carl E. Wagner, Karen Liby. The novel rexinoid V-125 reduces tumor growth in the MMTV-Neu model of breast cancer and the A/J model of lung cancer via immunomodulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1118.

Abstract 5378: PMD-026, a first in class oral RSK inhibitor, demonstrates activity against hormone receptor positive breast cancer with acquired CDK4/6 inhibitor resistance

Abstract PMD-026 is a first in class, reversible, oral small molecule inhibitor of p90 ribosomal S6 kinase (RSK), a kinase family activated by the MAPK, PDK-1 and PI3K pathways, which regulate substrates involved in cancer cell proliferation and drug resistance. Specifically, both MAPK and PI3K pathways are implicated in resistance to standard of care (SOC) CDK4/6 inhibitors in hormone receptor positive (HR+) breast cancer (BC). RSK2 is expressed in 80% of HR+ BC, therefore we hypothesized that disrupting these critical pathways with PMD-026 could overcome resistance to CDK4/6 inhibitors through cell growth inhibition, apoptosis induction and downstream target inhibition alone and in combination with SOC SERD fulvestrant. In preclinical studies and a Phase I/Ib clinical trial in metastatic BC, PMD-026 demonstrated a good safety profile, making it an ideal candidate for the CDK4/6 inhibitor resistant HR+ BC population. Here in we demonstrate that PMD-026 inhibits growth of HR+ BC cell lines MCF-7 and T47D in vitro at IC50 values ranging from 3.7 to 10.1 µM, resulting in dephosphorylation of the RSK downstream effector YB-1 and induction of apoptosis through PARP cleavage. Comparatively, the MAPK pathway remains active in the presence of fulvestrant, as indicated by the expression of pYB-1. We determined that PMD-026 synergizes with fulvestrant in the MCF-7 model in vitro with a combined drug index (CDI) of 0.73 to 0.92. The next step was to determine if this combination is effective in cells resistant to CDK4/6 inhibitors. For that purpose, MCF-7 and T47D cells were treated with increasing concentrations of the CDK4/6 inhibitor palbociclib (Ibrance) up to 2 µM for several months. The generated Ibrance resistant cell lines (MCF-7-IBR, T47D-IBR) are insensitive to Ibrance up to 2 µM, but their parental counterparts have IC50 values ranging from 0.05 to 0.15 µM. In addition, cross-resistance to an additional CDK4/6 inhibitor, abemaciclib (Verzenio), was observed in the resistant cell lines, but the parental lines remained sensitive at IC50 values ranging from 0.15 to 0.25 µM. Most importantly, both parental and resistant cell lines remained sensitive to PMD-026 at similar IC50 values, indicating that CDK4/6 inhibitor resistance does not affect PMD-026 sensitivity. PMD-026 was then tested in combination with fulvestrant in anchorage independent conditions in the MCF-7-IBR cells. It was determined that this combination was highly synergistic with CDI ranging from 0.55 to 0.79. Together, these data support the application of PMD-026 and fulvestrant as a novel method to stop the growth of HR+ BC with acquired resistance to CDK4/6 inhibitors. Additionally, given that the MAPK pathway is upregulated in response to PI3K inhibition, the PMD-026 and fulvestrant combination is a potential alternative treatment for HR+ BC patients. Citation Format: Aarthi Jayanthan, Lambert Yue, My-my Huynh, Gerrit Los, Sandra E. Dunn. PMD-026, a first in class oral RSK inhibitor, demonstrates activity against hormone receptor positive breast cancer with acquired CDK4/6 inhibitor resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5378.