Bayer, Blaise

Abstract Background: Bria-IMT™ is an allogeneic whole-cell cancer vaccine, designed to stimulate anti-tumor immunity (Chumsri et al 2024 ASCO). Bria-ABC (NCT06072612) is the multicenter, randomized, open-label trial evaluating overall survival (OS) of Bria-IMT™ regimen vs treatment of physician’s choice (PC) in patients with MBC where no meaningful therapy exists. Methods: 3 arm randomized 1:1:1 (Bria-IMT, Bria-IMT+CPI, or PC) in late stage heavily pretreated pts with MBC. Pts can be ECOG <2, Pts w/ CNS mets and/or who have received prior CPI or ADCs are allowed. The Bria-IMT™ regimen includes preconditioning w/ cyclophosphamide (300 mg/m2) on day -2/-3, intradermal SV-BR-1-GM inoculations (x4) on day 0, and interferon at inoculation sites (Days 1-3). CPI (retifanlimab 375 mg) may be given between days -2 to 2. The regimen is administered every 3 weeks (Q3W). Pts randomized to the monotherapy arm (Bria-IMT™ alone) may cross over to the combo arm upon disease progression. Response assessments are planned Q6W for the first cycle, and then Q8W thereafter. Based on prior data, an interim HR of 0.6 at 144 events will constitute early success. Overall study design anticipates 404 total pts. Results: This interim, unaudited data reflects ongoing enrollment and trial feasibility. To date, 61 pts have completed screening, with 40 pts randomized. Screened pts had a median age of 56 (range 35-82). For pts with evaluable data (n=40), median BMI was 25.6 kg/m2 (8.7-45.7) with a median of 6 (2-13) prior lines of therapy. 20 pts (50%) had HR+/HER2- breast cancer, 18 HR-/HER2- (45%), and 2 HER2+ (5%). Baseline ECOG PS were: 0 (55%), 1 (35%), 2 (10%). In biomarker-evaluable pts, circulating tumor cells were present at baseline in 30% (mean: 10.1 cells/mL; range: 0-139), while cancer-associated macrophage-like cells (CAMLs) were present in all pts (mean: 18.3 cells/mL; range: 1-154). In pts with available follow-up data, median change in CAML count from baseline to most recent cycle was -23.5%. In pts with available HLA typing, match distribution was 0 (19%), 1 (35%), 2 (26%), 3 (16%), and 4 (3%), 8 (26%) class 1, 8 (26%) class 2, and 9 (29%) matching both alleles informing potential immune response interactions with Bria-IMT™. Local injection site reaction (DTH), tumor-marker serum level, and circulating cancer cells, will be analyzed across subtypes to further characterize the pt population. The Bria-IMT™ regimen has been generally well tolerated, with no Tx D/C due to adverse events (AEs). The most frequently reported AEs include nausea (30%), constipation (22.5%), injection site rxn (22.5%), and headache (17.5%) w/ no interstitial lung disease reported. Discussion: Bria-ABC enrollment is ongoing. Future analyses will assess OS, PFS, ORR, CBR, QoL, and CNS event-free survival as data becomes available. Expected to close to enrollment by 2025, with final analyses planned for 2026. Citation Format: Saranya Chumsri, Joyce A. OShaughnessy, Azka Ali, Christopher N. Vaughn, Lawrence M. Negret, Adam Brufsky, Regina Stein, Marcela Salgado, Blaise Bayer, Giuseppe Del Priore, Sara A. Hurvitz. Bria-ABC vs physician choice in late stage MBC: Early biomarker correlates of the randomized registration trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB408.

Abstract Background: Bria-IMT™ is a combination immunotherapy consisting of allogeneic whole-cell cancer vaccine (SV-BR-1-GM) administered w/ immune checkpoint inhibitor (CPI). SV-BR-1-GM breast cancer cells have been engineered to directly stimulate anti-tumor immunity through expression of tumor-associated antigens and secretion of GM-CSF to enhance dendritic cell activation. Addition of CPI potentiates SV-BR-1-GM to overcome the immune-suppressive tumor microenvironment. Methods: This Phase I and randomized phase II combination study evaluated the Bria-IMT™ regimen: preconditioning w/ CTX (300 mg/m2) on day -2 or -3, SV-BR-1-GM inoculation and CPI administration on Day 0, and low-dose peg- interferon α at inoculation sites 2 (±1) day post-SV-BR-1-GM. Phase II pts were randomized 1:1 to receive CPI at cycle 1 (immediate) or cycle 2 (delayed). Two SV-BR-1-GM formulations (w/ and w/o IFNγ incubation) were evaluated. Biomarkers included cancer-associated macrophage-like cells (CAMLs), circulating tumor cells (CTCs), PD-L1 scores, and delayed-type hypersensitivity (DTH) skin tests. Results: 54 pts (22 in Phase I, 32 in Phase II) enrolled. 11 pts received pembrolizumab, 44 retifanlimab, w/ 1 pt transitioning from pembrolizumab to retifanlimab. Median age 61(38-81) years; median 6(2-13) prior regimens. 33(61%) pts were ER+/PR+/HER2-, 18(33%) TNBC, and 3(6%) HER2+. Bria-IMT regimen was well tolerated, w/ no attributable Tx D/C. 67% of adverse events grade 1-2; 13% ≥ grade 3 including pulmonary embolism, increased lipase, and dehydration. Median overall survival (OS) was 9.9 (1.8 - 30.3) mos w/ 13% of pts in active survival follow-up. Median progression free survival (PFS) was 3.2 (1.1-16.5) mos w/ 1 pt still in treatment (16.5 mos). Pts treated w/ ph 3 formulation (w/o IFNγ; N = 37) had significantly improved PFS (3.6 vs. 2.6 mos, P=0.01) and OS (13.4 vs. 6.9 mos, P=0.01); in evaluable pts, objective response rate was 14% and clinical benefit rate 61%. Randomized pts receiving ph 3 formulation had not reached median OS. In randomized pts, C1 vs C2 CPI initiation showed greater PFS (3.7 vs. 3.2 mos, P=0.09) and OS (11.4 vs. 7.4 mos, P=0.19). OS in pts w/ no HLA match was undefined vs 8.6 mos in pts w/ any match (P = 0.04). DTH (+) vs (-) correlated w/ greater OS (11.9 vs. 4.7 mos, P= <0.0001) and PFS (3.5 vs. 2.4 mos, P=0.001). Conclusion: Randomized phase 2 Bria-IMT demonstrated efficacy and safety in heavily pretreated MBC. Post-progression survival exceeding median OS in pts still undergoing survival follow-up suggests long-term benefit extending beyond treatment period. C1 vs C2 CPI initiation showed no statistical or clinically significant difference in OS. Superior outcomes w/ phase 3 formulation support its use in future trials. These results confirm earlier reports of the trial and an even greater benefit. A randomized phase 3 trial is ongoing comparing Bria-IMT vs treatment of physician's choice (NCT06072612). Trial Information: NCT03328026 Citation Format: Saranya Chumsri, Chaitali Nangia, Minal Barve, Kendrith Rowland, Ralph Boccia, John Knecht, Blaise Bayer, Marcela Salgado, Tamar Aghajanian, William V. Williams, Charles Wiseman, Giuseppe Del Priore, Carmen Calfa. Survival outcomes in a randomized phase 2 ofBria-IMT: An allogeneic whole cell cancer vaccine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr CT100.

e13119 Background: Breast cancer metastasis to the central nervous system (CNS) and intracranial area often leads to severe morbidity and mortality. While systemic treatments manage systemic tumors, their impact on CNS/intracranial metastases is limited. Cell based therapies like SV-BR-1-GM may overcome this limitation. SV-BR-1-GM is a GM-CSF secreting, antigen-presenting immortalized breast cancer cell line. We report its efficacy on CNS tumor regression. Methods: Post-hoc analysis of a subset of all advanced MBC patients with CNS/intracranial metastases from previous phase 1, 2, and an ongoing randomized phase 2, trials (n=7 subjects) of SV-BR-1-GM. Bria-IMT monotherapy (intradermal SV-BR-1-GM + cyclophosphamide 300 mg/m2, +interferon-alpha) was administered q3wks to 2 subjects; an immune checkpoint inhibitor (ICI) was administered with each cycle in the combination setting (n=5). Results: There were 7 patients with intracranial metastases at baseline of whom 5 had intracranial tumor responses. Of the 5 responders, median pt age = 66 (range 58-70), median prior lines = 5.5 (3-13), and median time from initial diagnosis = 7.5 years (3-10). 4/5 pts had ≥1 HLA class match with SV-BR-1-GM. 3 were HR + and 1 HER2 +. Pt A002 (ER+/PR+, HER2-) received 6/6 planned cycles, achieving an 83% reduction in breast lesions; after 3 months off therapy, imaging revealed multiple brain metastases and recurrence of right breast lesions. Following 3 additional cycles there was marked regression in both brain and breast lesions. Pt 02-003 (ER-/PR-, HER2 1+ (IHC)) received 5 cycles of SV-BR-1-GM and observed a 60% reduction (5mm -> 2mm) in a left parietal periventricular lesion, and complete resolution (CR) of a left parietal lobe. Pt 06-005 (ER+/PR-, HER2 1+) demonstrated a 56% (9mm -> 4mm) reduction in the thickness of a dural lesion overlying the left anterior temporal lobe after 6 cycles of SV-BR-1-GM + ICI. After 2 additional cycles of SV-BR-1-GM + ICI and 1 cycle of SV-BR-1-GM (ICI skipped on final cycle due to grade 2 AE), patient achieved CR of a left orbital mass observed at baseline (24mm -> 0m). Pt06-007’s (ER-/PR-, HER2 1+) CNS lesions showed a median reduction of 49% compared to baseline after 3 cycles. Pt 11-018 (ER+/PR-, HER2 +) showed standard progression (SD) at initial restaging; 14% increase in sum of diameters of intracranial metastasis. Subsequent imaging, after 3 cycles, showed significant orbital tumor reduction along with reported improvement in eye pain. Conclusions: This post-hoc analysis demonstrated promising efficacy of the Bria-IMT regimen either alone or in combination with ICIs in CNS/intracranial metastasis. The CNS/intracranial regression seen across all breast cancer subtypes among heavily pretreated patients highlights the potential of SV-BR-1-GM in managing CNS metastasis. Ongoing trials will further evaluate the efficacy of the Bria-IMT regimen in patients with CNS/intracranial metastasis. Clinical trial information: NCT03328026 .

1087 Background: Antibody-drug conjugate (ADC) sequencing raises concerns of cross-resistance due to their shared targets and cytotoxic payloads. Consequently, treatments after ADCs in heavily pretreated MBC is uncertain. SV-BR-1-GM, a GM-CSF secreting, antigen-presenting immortalized breast cancer cell line, has emerged as a post ADC solution (1) based on a different MOA. We now report the results of SV-BR-1-GM in ADC treated patients. Methods: Post-hoc analysis of an ongoing randomized Phase 2 censored to the data-cut date prior to data lock. Bria-IMT (~20x106 SV-BR-1-GM cells, intradermally 48-72 hours after ctx (300 mg/m2), followed by interferon-alpha 2 days later) administered q3wks with a checkpoint inhibitor (CPI). Adverse events were classified according to their severity and relationship to treatment regimen. Results: Among 54 advanced MBC patients randomized, 23 who failed prior ADC therapy were identified. All were heavily pretreated (median 6 prior lines, range 3 – 13). Median age 62 (41-83). 14 pts had HR+/HER2-, 5 TNBC, and 2 HR+/HER2+ MBC. The remaining were HR-/HER2+ or HR-/HER2 low. 8 pts received > 1 ADC. Prior ADCs included: 4 ado-trastuzumab emtansine, 14 trastuzumab deruxtecan, 13 sacituzumab govitecan. 7 pts had also received ≥ 1 prior CPI line. To date, pts received a median 3 cycles of Bria-IMT™ + CPI (2-8). Kaplan-Meier analysis revealed a median OS of 42 weeks with survival of 69% at 6 months. The subset experienced a median PFS of 74 days with 40% of pts demonstrating a Bria-IMT PFS (PFS2) similar to or > their prior line PFS (PFS1). 39% of pts experienced a PFS2 ≥ their most recent line of ADC PFS. The disease control rate was 40% among evaluable pts. 43% of pts had a reduction in cancer-associated macrophage-like cell (CAML) levels; median reduction was 36% (22-98%) after 1 cycle. There were no toxicity-related treatment discontinuations. 43% (10/23) reported grade 3 or 4 AEs, independent of study drug causality. AEs included injection site reaction (39%), fatigue (26%), and nausea/vomiting (43%), mostly mild to moderate. One case of elevated lipase was the most clinically significant grade 4 AE. No interstitial lung disease (ILD) was reported. Conclusions: This subset analysis of the Bria-IMT regimen in ADC refractory MBC patients suggests a potential clinical benefit and treatment option for this patient population. The absence of serious AEs, notably interstitial lung disease (ILD), and no toxicity-related treatment discontinuations, underscores the regimen's favorable safety profile. Future studies are warranted to confirm these results and explore the potential of Bria-IMT™ in broad clinical settings of heavily pretreated contemporary MBC patients. 1. Kamaraju 2024 AACR. Clinical trial information: NCT03328026 .

1022 Background: The Bria-IMT regimen is a combination immunotherapy using an allogeneic whole cell cancer vaccine combined with checkpoint inhibitors (CPIs). Intradermally administered irradiated SV-BR-1-GM breast cancer cells secrete GM-CSF and present tumor associated antigens (TAAs) on HLA-I and –II molecules to directly stimulate anti-tumor immunity. Anti-PD1 CPI further stimulates T-cells and synergizes with SV-BR-1-GM. Here we report the results of the phase 1/2 trial (NCT03328026) of Bria-IMT in metastatic/advanced breast cancer evaluating sequencing of SV-BR-1-GM inoculation and CPI. Methods: Analysis of the phase 1 with expansion phase 2 cohort randomized by sequence using SV-BR-1-GM, checkpoint inhibitor (pembrolizumab or retifanlimab), low dose cyclophosphamide (Day –2) and post-dose local pegylated interferon α, with cycles every 3 weeks. In the 1:1 randomized cohort, CPI is either dosed at C1 prior to SV-BR-1-GM (original sequence) or delayed to C2 post-SV-BR-1-GM (alternative sequence). Cancer-associated macrophage-like cells (CAMLs) and circulating tumor cells (CTCs) were monitored as biomarkers. Results: A total of 54 patients were dosed: 11 with pembrolizumab, 44 with retifanlimab (1 patient received pembrolizumab and later retifanlimab). Median age=61 (38-81); Median prior regimen=6 (2-13); 72% ER+/PR+/HER2-; 6% HER2+ and 22% triple negative. Bria-IMT regimen was well tolerated with only 9% drop-out rate due to AE. AEs related to IPs were seen in 74% of patients; the majority (91%) being grade 1-2, and few (1.7%) grade 4 cases including pulmonary embolism, dehydration and increased lipase. Among 30 patients with post-dose CAML/CTC data and evaluable outcome, CAML count <5 associates with disease control (p=0.06, Chi square test). Patients who developed DTH to SV-BR-1-GM had significantly better PFS and higher OS. Patients treated with phase III formulation had an increase in PFS. Quality of life improvement correlates with disease outcome and survival. Among the patients treated with the phase III formulation of SV-BR-1-GM (n=23 with evaluable outcomes), objective response rate (ORR) is 13% and disease control rate (DCR) is 61%, with median PFS and OS are 4.1 and 13.3 months, respectively. In the randomized portion, the original sequence cohort had higher DCR (43% vs 36%) and OS (P=0.08, HR 0.30, 95%CI 0.08-1.17) compared to the alternative sequence cohort. Conclusions: BRIA-IMT has shown a favorable safety profile while providing benefits to heavily treated aMBC patients. Superior outcomes and survival were seen in patients treated with the phase III formulation and regimen now being used in the ongoing Ph3 trial, confirming the improvement in efficacy of the novel regimen. The results from this randomized phase 2 study informed the study design of the ongoing Ph3 trial comparing BRIA-IMT to standard of care physician choice treatments (NCT06072612). Clinical trial information: NCT03328026 .

Abstract Background: Antibody-drug conjugate (ADC) sequencing raises concerns of cross-resistance due to their shared cytotoxic payloads. Consequently, there is a pressing need for treatments after ADCs, especially in heavily pretreated patients. Immunization with irradiated SV-BR-1-GM, a GM-CSF secreting, antigen-presenting immortalized breast cancer cell line, has emerged as a potential post ADC solution based on a different mechanism of action. This retrospective analysis aims to assess the overall efficacy and safety of SV-BR-1-GM in a subset of ADC treated patients. Methods: Post-hoc subset analysis of the ongoing randomized Phase 2 study identified 23 advanced MBC patients who failed prior ADC therapy. Bria-IMT™ (irradiated SV-BR-1-GM ~20x106 cells, intradermally 48-72 hours after cyclophosphamide (300 mg/m2), followed by interferon-alpha at the inoculation sites 2 days later) was administered q3wks with a CPI. Endpoints included PFS, OS and disease control rate (the proportion of patients with stable disease, partial or complete responses) using the KM method censored to the data-cut date prior to data lock. Adverse events were classified according to their severity and relationship to treatment regimen. Results: All pts were heavily pretreated (median 6 prior lines, range 3 - 13). Median age was 62 (41-83). 14 pts had HR+/HER2-, 5 TNBC, and 2 HR+/HER2+ MBC. The remaining pts were HR-/HER2low or HR-/HER2+. Prior ADCs included: 4 ado-trastuzumab emtansine, 14 trastuzumab deruxtecan, 13 sacituzumab govitecan; 8 pts received &gt; 1 ADC. 7 pts had also received ≥ 1 prior CPI line. To date, pts received a median 3 cycles of Bria-IMT™ + CPI (2-7). Kaplan-Meier analysis revealed a median OS of 42 weeks with survival of 69% at 6 months. The subset experienced a median PFS of 74 days with 40% of pts demonstrating a Bria-IMT PFS (PFS2) similar to or &gt; their prior line PFS (PFS1). 39% of pts experienced a PFS2 ≥ their most recent line of ADC PFS. The disease control rate was 40% among evaluable pts. 43% of pts had a reduction in cancer-associated macrophage-like cell (CAML) levels; median reduction was 36% (22-98%) after 1 cycle. There were no toxicity-related treatment discontinuations. 43% (10/23) reported grade 3 or 4 AEs, independent of study drug causality. No interstitial lung disease (ILD) reported. AEs included injection site reaction (39%), fatigue (26%), and nausea/vomiting (43%), mostly mild to moderate. One case of elevated lipase was the most clinically significant grade 4 AE. Conclusion: The retrospective analysis of the Bria-IMT™ regimen in ADC refractory MBC patients suggests a potential treatment option for this patient population. The absence of serious AEs, notably ILD, and no toxicity-related treatment discontinuations, underscores the regimen's favorable safety profile. Future studies are warranted to confirm these results and explore the potential of Bria-IMT™ in broader clinical settings. Citation Format: Chaitali Nangia, Carmen Calfa, Blaise Bayer, Mingjin Chang, William Williams, Giuseppe Del Priore, Charles Wiseman, Saranya Chumsri. Efficacy and safety of SV-BR-1-GM after progression on ADC in metastatic breast cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT206.