Kahn, Adriana

2652 Background: Circulating Tumor Cells (CTCs) are prognostic for poor outcomes in metastatic Breast Cancer (mBC), however CTCs are uncommon in mBC (<20%) and many pts without CTCs often progress. Cancer associated macrophage-like cells (CAML) are prognostic inflammatory pro-tumorigenic PD-L1 expressing macrophages common in mBC pt blood (>90%). In a previous randomized phase II trial, CTC & CAML decreases post Bria-IMT induction correlated with clinical benefit. Bria-IMT is an allogenic whole cell vaccine engineered to express tumor associated antigens & GM-CSF, promoting adaptive & innate immune responses. The ongoing Bria-ABC (NCT06072612) phase 3 study compares Bria-IMT to physician’s choice (TPC) in late stage mBC. We present interim results, without treatment arm comparison, for Progression Free Survival (PFS) by CTC & CAML changes as the exploratory part of the trial. Methods: This still blinded ongoing multicenter randomized open label Phase 3 trial evaluates Bria-IMT+ checkpoint inhibitor (CPI) vs TPC in mBC pts lacking approved therapies. Pts are randomized 1:1:1 to Bria-IMT+CPI, TPC, or Bria-IMT monotherapy (discontinued after 150 pts). The Bria-IMT consists of cyclophosphamide, irradiated SV-BR-1-GM cells, micro-dose pegylated α IFN at each inoculation site. CPI is administered day -3 to 3. TPC followed standard of care. Blinded anonymized blood was taken at baseline (BL), prior to therapy & 2nd (T1) taken at cycle 3 (~4 weeks post initiation). CTCs & CAMLs, and PD-L1 expressions, were quantified using LifeTracDx liquid biopsy with analysis of PFS by censored univariate analysis. Results: At time of analysis, >250 consented, >170 randomized, 119 had BL and 78 had T1. Median age 56 yrs [34–83], median 6 [2–13] prior lines of therapy, 31% TNBC, 62% ER+/PR+, & 15% HER2+. ≥1 CTCs were found in 25% (30/119) at BL & 22% (17/78) at T1. ≥1 CAMLs were found in 93% (111/119) at BL & 95% (74/78) at T1. At BL, ≥1 CTC was not significant for PFS (HR=1.7, CI95% 1.0-2.9, p=0.0513), but ≥2 CTCs was significant for worse PFS (HR=1.8 CI95% 1.1-3.1, p=0.0480). At T1, ≥1 CTCs nor ≥2 CTCs correlated with PFS (HR=0.9, p=0.8392) & (HR=1.6, p=0.1079), respectively. Further, a decrease in CTCs was seen in 11 pts but did not correlate with PFS (HR=0.7, p=0.6552). ≥1 CAML at BL nor T1 correlated with PFS (HR=1.2 CI95% 0.7-2.0, p=0.6811) or (HR=0.9 CI95% 0.7-2.5, p=0.5307), respectively. However, 51 pts (65%) had a decrease or stable CAML counts between BL & T1 which did significantly correlate with better PFS (HR=2.2 CI95% 1.2-3.9, p=0.0154). Conclusions: In an ongoing analysis of a heavily treated mBC pts, we observed that in the entire blinded population, 65% of pts had stability/drop in CAMLs significantly correlated with better PFS. Treatment arm specific comparisons will not be unblinded until completion of the designated milestone (144 mortalities). Clinical trial information: NCT06072612 .

1107 Background: Bria-IMT is an allogeneic whole cell immunotherapy expressing tumor associated antigens and GM-CSF to stimulate adaptive and innate immunity. The phase 3 Bria-ABC trial (NCT06072612) evaluates Bria-IMT + retifanlimab vs physician’s choice in MBC w/ no meaningful therapeutic options. Characterization of on-trial pt experience, including quality of life (QOL) and tolerability, remains clinically relevant yet underreported. We evaluated QoL and toxicity to assess feasibility of home self administration. Methods: EORTC QLQ-C30 at baseline (BL) and subsequent visits. Raw item responses were aggregated into domain scores. Changes quantified as absolute point differences; domain scores defined as medians of constituent items. Lower functional/symptom and higher global scores indicate better outcomes. Wilcoxon matched pairs test assessed change from BL. Missing QoL data handled by observed cases approach. QoL evaluated at BL, V3, V6, and V9. TWiST and TOX summarized descriptively. TOX defined as cumulative time w/ grade ≥3 TEAEs w/o progression; TWiST as time w/o grade ≥3 toxicity or progression. TOX and TWiST constitute component health states for planned QTWiST analysis pending mature OS. Results: At submission, 251 pts screened, 173 randomized, 147 treated. 75% Caucasian, 20% other, 5% not reported; median 6 prior lines (2-15); ECOG 2 -6%; intracranial mets 9%; 42% HR+, 37% TNBC, 12% HER2+. Median 5 QoL assessments/pt completed. 127 pts completed ≥2 assessments. Paired data available at V3 52%, V6 17%, V9 6%. Global health medians BL 5.0, V3 5.0, V6 5.0, V9 4.5. Score maintenance/improvement: @V3 63% (p=0.7), V6 62%, V9 71%. Functional domains: role (BL 1.5, V3 2.0, V6 2.0, V9 2.0; maintenance 62.7% [p=0.02], 52.4%, 71.4%). Physical (BL 1.0, V3 2.0, V6 2.0, V9 2.0; maintenance 68.7% (p=0.002), 47.6% (p=0.03), 71.4%), cognitive (BL 1.5, V3 1.5, V6 1.5, V9 1.5; maintenance 63.6%, 61.9%, 85.7%). Emotional (BL 1.5, V3 1.5, V6 1.5, V9 1.5; maintenance 75.8% (p=0.9), 81.0%, 85.7%). Social (BL 1.5, V3 1.5, V6 2.0, V9 2.5; maintenance 58.5%, 75.0%, 57.1%). Symptoms: nausea/vomiting (1.0 throughout; maintenance V3 73%, V6 86%, V9 86%), fatigue median 2.0 all timepoints; maintenance 61%, 67%, 71%), pain (BL/V3 1.5, V6/V9 2.0; maintenance V3 57% [p=0.03], V6 62% [p=0.9], V9 86%). TWiST and TOX restricted mean 3.12 mo and 0.63 mo, respectively; 83.2% and 16.8% of observed follow-up. Pts w global health maintenance demonstrated longer median TWiST v deterioration (4.3 v 2.7 mo). ECOG stable in 78% (n=99). Conclusions: Heavily pretreated MBC pts in Bria-ABC demonstrated stable global health and key functional domains. Findings support sustained QoL in advanced disease. TWiST demonstrates meaningful benefit w/o significant toxicity. Ongoing follow up will further characterize durability of pt-reported outcomes and clinical correlation. Results support decentralized care and potential home self administration. Clinical trial information: NCT06072612 .

Abstract Background: Bria-IMT™ is an allogeneic whole cell immunotherapy expressing tumor associated antigens and GM-CSF, designed to stimulate adaptive and innate immune responses. The ongoing multicenter phase 3 Bria-ABC trial (NCT06072612) evaluates Bria-IMT + Retifanlimab vs physician’s choice in pts with metastatic breast cancer who have exhausted standard therapies. Quality of life characterization in this advanced disease setting is clinically relevant yet underreported. Methods: QOL was assessed using the European Organization for Research and Treatment of Cancer QOL Questionnaire Core 30 (EORTC QLQ-C30) at baseline (BL) and treatment visits. Raw item responses (scale: 1 - 4 for functional/symptom items; 1 - 7 for global health ; lower scores = better functional/symptom outcomes; higher scores = better global health) were aggregated into domain scores. Changes from BL were quantified as absolute point differences on response scales and domain level scores are the median of constituent items. Changes from BL assessed using Wilcoxon matched-pairs signed-rank tests. ECOG status assessed at BL and each treatment visit. TEAEs graded per CTCAE. Missing QOL data handled using observed cases approach. We report QoL outcomes at visits (V) BL, 3, 6, and 9 to characterize pt experience during treatment. Results: As of data cut date, 235 pts have been screened, 169 randomized,129 treated. Median age: 60. 74% Caucasian; 18% other; 8% not reported; median 6 prior lines (2-15); ECOG 2: 7%, intracranial mets: 11%. 51% of pts HR+, 37% TNBC, 10% HER2+, 2% not reported. mPFS 2.9 mo (95% CI, 2.3 - 3.7), median of 5 QoL assessments per pt. Of 127 pts who completed ≥2 EORTC QLQ-C30 assessments, 67 (52%), 21 (17%), and 7 (6%) had paired data available at V3, 6, and 9, respectively. Global health status remained stable (median: BL 5.0, V3 5.0, V6 5.0, V9 4.5; 63% of pts reported maintenance or improvement at V3 [p=0.7], V6: 62%, V9: 71%). Functional domains: physical (median: BL 1.0, V3 2.0, V6 2.0, V9 2.0; 68.7% , 47.6% [p=0.03], 71.4% maintenance), role (BL 1.5, V3 2.0, V6 2.0, V9 2.0; 62.7% [p=0.02], 52.4%, 71.4% maintenance), emotional (BL 1.5, V3 1.5, V6 1.5, V9 1.5; 75.8% [p=0.9], 81.0%, 85.7% maintenance), cognitive (BL 1.5, V3 1.5, V6 1.5, V9 1.5; 63.6% [p=0.2], 61.9%, 85.7% maintenance), and social functioning (BL 1.5, V3 1.5, V6 2.0, V9 2.5; 58.5% [p=0.06], 75.0%, 57.1% maintenance). Symptoms: fatigue (median 2.0 at all timepoints; 61%, 67%, 71% maintenance), nausea/vomiting (1.0 throughout; 73% maintenance at V3 [p=0.8], V6 86% , V9 86%), and pain (1.5 at BL and V3, increasing to 2.0 at V6 and V9, w/ 57% maintenance at V3 [p=0.03], V6 62% [p=0.9], and V9 86%. ECOG status remained stable in 78% (n = 99) of pts during treatment. Most common TEAEs were fatigue, nausea, anemia, and constipation; w/ 45% Grade 3 or 4; 84% &lt; grade 3. QoL trends consistent w/ observed ECOG status and AE profiles. Conclusion: Heavily pretreated metastatic breast cancer pts demonstrated stability in overall health status and key functional domains during treatment. These findings are encouraging w/ a meaningful QOL in a population with advanced disease and limited therapeutic options. These observations and AE profile support decentralized clinical trial initiatives including home self-administration. Ongoing follow up will further characterize the durability of pt reported outcomes and their relationship w/ clinical status. Citation Format: Saranya Chumsri, Chaitali Nangia, Adriana Kahn, Lawrence Negret, Carmen Calfa, Blaise Bayer, Giuseppe Del Priore, Tamar Aghajanian, William Williams, Kelly McCann. QOL outcomes in Bria-ABC late stage metastatic phase 3 trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(8_Suppl):Abstract nr CT137.