Batalini, Felipe

Abstract Objective The validity of progression-free survival (PFS) as a surrogate for overall survival (OS) in the antibody-drug conjugate (ADCs) era remains uncertain. We evaluated the association between treatment effects on PFS and OS in randomized trials of ADCs for metastatic breast cancer (mBC) and explored the surrogate threshold effect (STE). Methods PubMed, Embase, Cochrane, and ClinicalTrials.gov were searched for published randomized controlled phase II–IV trials evaluating ADCs in mBC and reporting hazard ratios (HRs) for both PFS and OS. A meta-epidemiological approach was used. The primary metric was the ratio of hazard ratios (rHR = HR_PFS/ HR_OS), with rHR < 1 indicating a larger effect on PFS. Trial-level associations were assessed using weighted linear regression (R²) and Spearman’s correlation. Results Twenty-one trials (n = 21; 18 phase III) evaluating nine ADCs were included. The pooled rHR was 0.79 (95% CI, 0.73–0.86), indicating a larger relative effect on PFS than OS. Numerically, the largest discrepancies were observed in triple-negative disease (rHR 0.72) and trials allowing crossover (rHR 0.71). Concordant statistical significance between endpoints occurred in 76% of the trials, whereas 24% showed a significant PFS benefit without OS improvement. The trial-level association between PFS and OS was moderate (R² = 0.62; ρ = 0.67). Conclusion Treatment effects on PFS consistently exceeded those on OS, although effect directions were highly concordant between endpoints. These findings provide an exploratory framework to contextualize the relationship between PFS and OS in ADC trials, requiring further validation in diverse clinical settings.

Abstract Background Patients with breast cancer undergoing chemotherapy experience multiple symptoms that cause decrements in quality of life. A deeper understanding of serum metabolites as biomarkers may guide in predicting symptom occurrence and severity. This study evaluated change in serum metabolite levels from before chemotherapy (T1) to after the initial first or second cycle of chemotherapy (T2), after the third cycle of chemotherapy (T3) and finally after a month of chemotherapy completion (T4). Change in metabolite levels were analyzed in association with symptom occurrence. Methods Patients with breast cancer (n = 10) completed study measures at four timepoints. Neuropsychological and gastrointestinal (GI) symptoms were evaluated using the Memorial Symptom Assessment Scale. Dietary intake was assessed using the NHANES Dietary Screener Questionnaire. Serum metabolites were analyzed using gas chromatography-mass spectrophotometry. Results Five patients experienced > 3 GI symptoms at T2 and T3. At all 4 timepoints, ≥ 6 patients experienced moderate to severe neuropsychological symptoms severity. Daily mean intake of fiber, whole grain, and calcium were less than the recommended guidelines. Compared to T1, long chain fatty acid and amino acid derivative levels decreased at T2 and T3 (p < 0.05). Increase in metabolite levels of glucose-6-phosphate (p = 0.02) and 6-phosphogluconate (p = 0.05) at T2 were associated with fatigue occurrence. Conclusions Patients experienced several gastrointestinal and neuropsychological symptoms during chemotherapy and early survivorship. Chemotherapy-induced changes in metabolites involved in cellular energy metabolism may explain patient symptom experience. Metabolite level changes overtime may reflect inadequate dietary intake. Larger sample size studies may guide in building metabolic prediction models for symptom burden.

e13076 Background: Progression-free survival (PFS) is frequently used as a primary endpoint in contemporary oncology trials, including antibody–drug conjugate (ADC) studies in metastatic breast cancer (MBC) settings, despite uncertainty regarding its validity as a surrogate for overall survival (OS). A meta-epidemiological analysis was performed to quantify the systematic differences between the treatment effects on PFS and OS in ADC randomized clinical trials (RCTs). Methods: Phase II–III ADC RCTs with MBC patients reporting hazard ratios (HRs) with 95% confidence intervals (CIs) for both progression-free survival (PFS) and overall survival (OS) were included. Differences in treatment effects within each trial were quantified using the ratio of hazard ratios (rHR = HR_PFS/HR_OS). Random-effects models were used to pool the rHRs across the trials. Prespecified subgroup and meta-regression analyses were used to evaluate the trial characteristics, clinical context, and regulatory status. Sensitivity analyses assessed the robustness across varying assumptions of the within-trial correlation between the endpoints. Results: Twenty-one RCTs evaluating nine ADCs in patients with MBC were included, comprising three phase II (14%) and 18 phase III (86%) studies. The pooled rHR demonstrated significantly larger treatment effects for PFS than for OS (rHR, 0.79; 95% CI, 0.73–0.86), with no between-trial heterogeneity (I² = 0%, τ² = 0). Sensitivity analyses assuming within-trial correlations between PFS and OS ranging from 0 to 0.95 yielded consistent results. Greater divergence between endpoints was observed in trials enrolling patients with triple-negative breast cancer (rHR, 0.72; 95% CI, 0.61–0.85) and HER2-low disease (rHR, 0.77; 95% CI, 0.62–0.96). Phase III trials showed larger differences than phase II trials (rHR, 0.79 vs. 0.89). When OS was a secondary endpoint, divergence was greater than when OS was primary (rHR, 0.77 vs. 0.87). Across trials, 16 of 21 studies (76%) demonstrated concordant effect directions between PFS and OS: 11 (52%) with a statistically significant benefit for both endpoints and 5 (24%) with neither endpoint significant. Discordance occurred in five trials (24%), all characterized by a statistically significant PFS benefit without a corresponding OS improvement. No trial demonstrated an OS benefit in the absence of a PFS benefit. Conclusions: Across ADC trials, PFS systematically overestimated OS treatment effects, underscoring the limitations of PFS as a standalone surrogate endpoint. These findings support the cautious interpretation of PFS-driven efficacy and reinforce the need for endpoint validation frameworks tailored to the mechanism, disease context, and trial design.

639 Background: Large cohort studies have shown a survival benefit with the use of GLP1 receptor agonists (GLP1 RA) in cancer patients. The impact of GLP1 RA usage in breast cancer (BC) and the different subtypes is unknown. To investigate the potential influence of GLP1 RA usage on BC survival, a study was conducted on a large institutional database. Methods: A de-identified institutional database identified newly diagnosed Stage I, II, and III BC patients from 2005 to present and use of GLP1 RA. The study compared survival rates for BC patients with and without GLP1 RA and further stratified by BC subtype [ER+HER2-, HER2+, ER-PR-HER2-(triple negative BC (TNBC))], BMI, and age. Kaplan-Meier survival curves were used to estimate overall survival. This study analyzed de-identified data accessed through Mayo Clinic Platform Discover. Per 45 CFR 46.102, this activity did not require IRB review. Data was extracted using an established privacy-preserving protocol and de-identified via expert determination under the HIPAA Privacy Rule. Raw EHR data and other unreported data cannot be shared due to de-identification parameters. Results: 88015 BC patients were identified, of which 3919 (4.5%) received GLP1 RA. The 5-year survival rate was 98.5% with vs 85.5% without GLP1 RA (p-value <0.0001). The survival benefit persisted for different BMI’s and ages: BMI >30 (98.4% vs 85.1%), >25 (98.4% vs 85.4%), and age <50 (99.5% vs 89.3%) and >50 (98.1% vs 84.8%) [all p<0.0001]. 21770 patients with ER+ disease were identified, of which 1412 (6.5%) received GLP1 RA. The 5-year survival rate was 99.0% vs 87.7% (p-value <0.0001). The survival benefit persisted by BMI and age: BMI >30 (99.0% vs 86.2%), >25 (98.9% vs 87.1%) and age <50 (99.6% vs 90.5%) and >50 (98.7% vs 87.2%) [all p<0.0001]. 3599 patients with HER2+ disease were identified, of which 202 (5.6%) received GLP1 RA. The 5-year survival rate was 99.3% vs 80.1% (p-value <0.0001). The survival benefit persisted by stratification: BMI >30 (100.0% vs 80.0%, p-value <0.0004), and <25 (97.7% vs 76.2%, p-value <0.019), and age <50 (100% vs 87.0%, p-value <0.043) and > 50 (99.0% vs 77.2%, p-value <0.0002). 8389 patients with TNBC disease were identified, of which 360 (4.3%) received GLP1 RA. The 5-year survival rate was 91.0% vs 71.9% (p-value <0.0001). The survival benefit persisted by stratification: BMI >30 (96.4% vs 72.9%, p-value <0.0001), >25 (93.2% vs 71.8%, p-value <0.0001), and age <50 (96.0% vs 73.0%, p-value <0.0028) and >50 (88.9% vs 71.8%, p-value <0.0001). For those TNBC patients who received GLP1 RA, having a BMI >30 conferred a protective effect with a 5-year survival rate was 97.9 vs 89.8% (p-value <0.0014). Conclusions: The study suggests that GLP1-RA improves 5-year survival rates of patients with BC and this applies to all subtypes of BC. These results suggest that further study of the impact of GLP1-RA on BC patients is warranted.

3109 Background: Poly(ADP-ribose) glycohydrolase (PARG) is an enzyme that catalyzes the removal of poly-ADP-ribose (PAR) chains from proteins during DNA damage repair. PARG inhibition leads to selective cell death in tumors with underlying replication fork defects, including BRCAm tumors, through a mechanism distinct from PARP inhibition. ETX-19477 is an oral, potent, and selective PARG inhibitor that shows robust preclinical activity in mouse models of ovarian, breast, and gastric cancers. Methods: ERADIC8 is an open-label, multicenter, Phase 1/2 study, consisting of two parts, dose escalation and dose expansion. A Bayesian Optimal Interval Design was used to enroll patients (pts) into dose escalation cohorts, with enrichment for pts with BRCAm high grade serous ovarian (HGSOC) and breast cancers. The primary objective is to assess safety/tolerability of ETX-19477 and define the maximum tolerated dose (MTD) and recommended Phase 2 dose(s). Secondary and exploratory objectives include pharmacokinetics, pharmacodynamics, and preliminary anti-tumor activity per RECIST v1.1. ETX-19477 is given orally once or twice daily in 21-day cycles. Results: As of Jan 6 2026, 45 pts were enrolled into the study across 11 dose levels (range: 80-750 mg QD, 190-350 mg BID). Tumor types included ovarian (n=24, BRCAm: 18), breast (n=8, BRCAm: 7), endometrial (n=6, BRCAm: 0), colorectal (CRC, n=3, BRCAm: 1), and other (n=4, BRCAm: 0) cancers. Treatment-related AEs (TRAEs; any grade) occurring in >20% of pts were nausea (53%), vomiting (38%), and fatigue (24%). The only Gr3 TRAE occurring in >5% of pts was neutropenia (16%). There was one Gr4 TRAE of neutropenia in 1 pt (2%) and no Gr5 TRAEs. ETX-19477 exposure is dose proportional, and the BID regimen achieves >85% PARG inhibition throughout the dosing interval in a blood-based PAR accumulation pharmacodynamic assay. As of the data cutoff, dose escalation is ongoing at 350 mg BID (MTD has not been defined) and dose expansion is ongoing at 200-300 mg BID. Among BRCAm, HGSOC pts enrolled at BID dose levels, there were 7 evaluable pts with a median of 4 prior lines of therapy (range 2–11): 2 pts achieved a partial response (PR, 29%) and 3 pts achieved stable disease (SD, 43%). Both pts with PRs were platinum-resistant and received prior PARP inhibitor treatment. 1 pt with BRCAm CRC remains on active therapy (250 mg BID) with SD for 7 months. Conclusions: ETX-19477 was well tolerated and showed anti-tumor activity in heavily pretreated pts with BRCAm, platinum-resistant HGSOC during dose escalation. These findings provide the first clinical proof-of-concept of PARG inhibition in HGSOC. ETX-19477 is being further evaluated in the dose expansion phase of the study. Clinical trial information: NCT06395519 .

PURPOSE Homologous recombination deficiency (HRD) is a key determinant of sensitivity to DNA-damaging agents; however, its genomic characterization in colorectal cancer (CRC) remains limited. This study investigated whether low RNA expression of homologous recombination (HR) genes identifies patients with metastatic CRC who derive survival benefit from oxaliplatin- or irinotecan-based therapy. METHODS A total of 22,957 metastatic CRC samples were subjected to DNA and RNA sequencing (Caris Life Sciences, Dallas, TX). Patients with microsatellite instability–high or pathogenic HR gene mutations were excluded to define a HR-proficient cohort. Overall survival (OS) was compared between patients with low (bottom 25%) versus high (top 25%) RNA expression of HR genes after oxaliplatin or irinotecan exposure. Validation was performed in the PARADIGM phase III trial cohort (n = 262) of first-line modified fluorouracil, leucovorin, and oxaliplatin-treated patients with available RNAseq data. RESULTS In the discovery cohort, low expression of core HR genes correlated with significantly longer OS after oxaliplatin or irinotecan exposure, specifically RAD51 (43.0 v 36.3 months; P < .005) and BLM (42.9 v 34.2 months; P < .005). Similar associations were observed for RAD51 (28.1 v 22.9 months; P = .02) and BLM (29.1 v 23.2 months; P < .005) in irinotecan-treated patients. In the PARADIGM validation cohort, low BLM expression was associated with improved OS (41.5 v 22.4 months; HR = 0.52; P = .002), whereas RAD51 showed a favorable but nonsignificant trend. These findings remained significant after adjustment for treatment arm, tumor sidedness, and metastatic burden. CONCLUSION Low BLM RNA expression is associated with improved survival after treatment with DNA-damaging agents, whereas low RAD51 expression shows a favorable but nonsignificant trend. These findings are exploratory and suggest that RNA-based HR gene expression may warrant further investigation as a potential prognostic biomarker in metastatic CRC.

Abstract Background: Up to 50% of patients with breast cancer experience chemotherapy-inducednausea (CIN) and 95% experience fatigue. A comprehensive understanding of biological mechanisms remains elusive. Herein, we evaluated the association of CIN and fatigue with clinical and multi-omics features, including serum and stool metabolites before (T1) to after chemotherapy (T2). Methods: Patients with breast cancer (n=36) who were to receive chemotherapy, provided symptom assessment using the Memorial Symptom Assessment Scale, stool and blood samples at T1 and T2. Patients provided dietary intake data using a Dietary Screener Questionnaire at T1. Descriptive and univariate analyses evaluated associations of co-occurringsymptoms and diet with CIN and fatigue at T2. Gut microbiome was sequenced using shotgun metagenomics. Targeted metabolomics was performed on stool and serum. Shift in the abundance of taxonomic groups and metabolite levels from T1 to T2 were evaluated in association with CIN and fatigue. Results: Approximately 64% of the patients experienced CIN and 94% experienced fatigue atT2. Three gastrointestinal symptoms co-occurred with CIN and fatigue. Higher daily average intake of calcium (p=0.013) and dairy (p=0.035) were associated with CIN. Levels of hexosylceramides, ceramide, phosphatidylcholine and sphingomyelins were significantly perturbed in association with CIN and fatigue (p&lt;0.05). Conclusion: CIN and fatigue are associated with perturbation in the sphingolipid turnover pathway, which negatively impacts functions in the gut-liver axis that include apoptosis activity and change in bile acid levels. Confirmatory studies are warranted to support the development of interventions to alleviate CIN and fatigue in patients with breast cancer receiving chemotherapy.Keywords: breast cancer; chemotherapy-induced nausea; fatigue; metabolites; sphingolipids Citation Format: Komal Preet Singh, Brenda J. Ernst, Jun Chen, Surendra Dasari, Felipe Batalini, Cindy Tofthagen, Kathryn J. Ruddy, Keenan Pituch, Linda Chlan. Perturbations in gut liver axis functions are associated with chemotherapy induced nausea and fatigue in patients with breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6309.

Abstract The INFORM trial (NCT01670500) was a randomized, two-arm Phase II neoadjuvant study comparing the efficacy of a platinum-based regimen (cisplatin) versus an anthracycline (AC)-based regimen in participants with germline BRCA1/2 mutations and early-stage, HER2-negative breast cancer. MicroRNAs (miRNAs) are emerging as promising non-invasive biomarkers for disease detection and treatment monitoring. The initial aim of this study was to evaluate whether pretreatment plasma miRNA profiles were associated with treatment outcomes in the INFORM trial cohort. Pretreatment plasma samples from 97 INFORM participants (n=53 cisplatin and n=44 AC) were screened for 352 miRNAs commonly implicated in cancer using the qPCR-based ID3EALTM Cancer Panel. Twenty out of 53 participants achieved residual cancer burden (RCB) score of 0 or 1 with cisplatin and 20/44 with AC. Higher plasma miR-362-3p expression was associated with a favorable response to cisplatin (1.7-fold; p&lt;0.01), but not to AC. MiR-362-3p expression in paired pretreatment tumor biopsies (n=79) did not significantly correlate with plasma expression and was not associated with RCB 0/1 (p&gt;0.05). In TCGA, miR-362-3p expression was higher in breast tumors than in adjacent normal tissue, and higher in triple negative breast cancers (TNBCs) compared with hormone receptor-positive tumors (both FDR&lt;0.001), independent of BRCA mutation or Single Base Substitution Signature 3 (SBS3) status. The miR-362-3p findings in INFORM did not replicate in a sister trial, TBCRC 030 (NCT01982448; 11 out of 46 cisplatin-treated patients achieved RCB 0/1, p=0.46). These results suggest that while miR-362-3p is unsuitable as a circulating biomarker for cisplatin response, it may play an important biological role in mediating cisplatin sensitivity in TNBCs, independent of BRCA1/2 mutations. Functional studies demonstrated that miR-362-3p is expressed and secreted by TNBC cell lines, operates as a tumor suppressor, and generally correlates with cisplatin sensitivity. Overexpression of miR-362-3p rendered MDA-MB-231 and CAL-51 cells cisplatin sensitive, while knockdown induced resistance in MDA-MB-436 cells. Ongoing studies are testing whether these effects translate in xenograft models. In silico and functional assays identified BCLAF1, a DNA damage response (DDR) regulator, as a direct target of miR-362-3p. Overexpression of miR-362-3p suppresses BCLAF1 mRNA and protein levels. Our findings demonstrate that miR-362-3p enhances cisplatin responsiveness by targeting BCLAF1. A miR-362-3p-based therapeutic may be useful as a co-agent to enhance tumor responses to platinum-based chemotherapy. Citation Format: Zhaoji Liu, Shizhong Ke, Xiaohui Li, Catherine Wu, Madison M. Uyemura, Brian R. Sardella, Erica S. Massicott, Lin Wang, Emily K. Aronson, Dimitra Karagkouni, Nikolas Kalavros, Ioannis S. Vlachos, Felipe Batalini, Cristina S. Bogsan, Jit Kong Cheong, Lihan Zhou, He Cheng, Phillip Munson, Erica L. Mayer, Judy E. Garber, Stuart J. Schnitt, Nadine M. Tung, Andrea L. Kasinski, Frank J. Slack, Gerburg M. Wulf, Yujing J. Heng. MiR-362-3p enhances platinum response in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 7903.

Abstract Platinum-based chemotherapy remains a cornerstone of treatment for triple-negative breast cancer (TNBC), yet the molecular determinants governing platinum response remain poorly defined. By leveraging the randomized Phase II INFORM trial, which compared neoadjuvant cisplatin to anthracycline-based therapy in BRCA1/2 -mutant breast cancer—we identified miR-362-3p as a specific regulator of cisplatin sensitivity. Higher plasma miR-362-3p expression was exclusively associated with favorable clinical outcome in the cisplatin arm, with no association observed in the AC arm, decoupling platinum-specific vulnerability from general chemotherapy response. We used gain- and loss-of-function TNBC models to establish that miR-362-3p functions as a potent sensitizer to cisplatin in vitro and in vivo . Integrated TCGA analysis and experimental validation identified BCLAF1, a key regulator of DNA damage response, as a direct repression target of miR-362-3p. We uncovered a novel role for the miR-362-3p/ BCLAF1 axis in overcoming platinum resistance in TNBC.