Chumsri, Saranya

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 .

550 Background: Residual disease after neoadjuvant chemotherapy (NAC) in HER2-positive breast cancer (BC) confers poor outcomes. Despite additional trastuzumab emtansine (T-DM1) in the adjuvant setting, a significant number of patients with residual disease still develop recurrence. H2NVAC is a multi-epitope T helper cell-activating peptide vaccine that is composed of 4 degenerate HER2-derived HLA-DR epitopes admixed with GM-CSF. Our previous phase I trial showed that this vaccine was safe and generated robust, long-lasting T and B cell immune responses. Methods: Patients with stage II-III HER2+ BC with any amount of residual disease in the breast /axilla after NAC were enrolled in a safety run-in phase of H2NVAC in combination with T-DM1. Patients were treated with H2NVAC and T-DM1 for 6 cycles, followed by 2 boosters at 3 and 12 months. Dose-limiting toxicity (DLT) was defined as any grade (G) ≥ 3 adverse events (AE) occurring within 21 days after the first vaccination. Results: A total of20 patients were enrolled with a median age of 51 years (range 27-69), 80% were White and 15% were Black. Most patients had hormone receptor-positive disease (90%). 40% were premenopausal, 40% were postmenopausal, and 20% were unknown. 14 patients had ypT1, 3 patients ypT2, 3 patients ypT3, 1 patient ypT4, 8 patients ypN0, 9 patients yp N1, 1 patient ypN1mi, and 2 patients ypN2. H2NVAC, in combination with T-DM1, was well tolerated, with no DLT being observed. Only grades 1 and 2 AEs were observed during the DLT period, with fatigue being the most common (G1 60%, G2 5%), followed by peripheral sensory neuropathy (G1 55%, G2 5%) and injection site reaction (G1 50%). Across all treatment cycles, the top 10 most common AEs that were at least possibly related to treatment include injection site reaction (G1 85%, G2 15%), AST increase (G1 65%), ALT increase (G1 45%), fatigue (G1 35%, G2 10%), peripheral sensory neuropathy (G1 35%, G-tube 10%), alk-phos increase (40% G1), nausea (G1 35%, G2 5%), arthralgia (G1 35%), myalgia (G1 25%, G2 5%), and platelet count decrease (G1 30%). There were four patients with G3 AEs at least possibly related to the vaccine observed after the DLT period, including allergic reaction, myositis/skin infection, urticaria, and pruritus/maculopapular rash. Conclusions: H2NVAC, in combination with T-DM1, was safe without DLT observed. The side effect profile was favorable, with the most common AE being the G1 injection site reaction. A multicenter, randomized, placebo-controlled, phase II trial of H2NVAC vs. placebo in combination with trastuzumab emtansine is currently ongoing through the ACCRU consortium. Clinical trial information: NCT04197687 .

Abstract Purpose: We previously reported that postmenopausal women with estrogen receptor-α–positive breast cancer receiving adjuvant anastrozole 1 mg/day (ANA1) with estrone (E1) ≥1.3 pg/mL and estradiol (E2) ≥0.5 pg/mL [inadequate estrogen suppression (IES)] had a threefold increased risk of a breast cancer event. The objective of this study was to determine if increasing anastrozole to 10 mg/day (ANA10) could result in adequate estrogen suppression (AES: E1 &lt;1.3 pg/mL and/or E2 &lt;0.5 pg/mL) among those with IES on ANA1. Patients and Methods: Postmenopausal women with estrogen receptor-α–positive breast cancer planning to receive adjuvant ANA1 were eligible. E1 and E2 were assessed pre- and post-8 to 10 weeks of ANA1. Those with IES were switched to 8- to 10-week cycles of ANA10 followed by letrozole 2.5 mg/day. E1 and E2 were assessed after each cycle. Anastrozole concentrations were measured post-ANA1 and post-ANA10. Primary analyses included patients who documented taking at least 80% of the planned treatment (adherent cohort). Results: In total, 132 (84.6%) of 156 eligible patients were ANA1 adherent. IES occurred in 40 (30.3%) adherent patients. Twenty-five (78.1%) of 32 patients who began ANA10 were adherent, and AES was achieved in 19 (76.0%; 90% confidence interval, 58.1%–89.0%) patients. Anastrozole concentrations post-ANA1 and post-ANA10 did not differ by estrogen suppression status among adherent patients. AES was maintained/attained in 21 (91.3%) of 23 letrozole-adherent patients. Conclusions: Approximately 30% of ANA1-adherent patients had IES. Among those who switched to ANA10 and were adherent, 76% had AES. Further studies are required to validate emerging data that ANA1 results in IES for some patients and to determine the clinical benefit of switching to ANA10 or an alternative aromatase inhibitor.

Abstract Background: Multiple studies have confirmed the central role of preexisting immune response measured by stromal tumor-infiltrating lymphocytes (sTILs) in triple-negative breast cancer (TNBC). Emerging studies showed that not only the number of TILs but also the location of TILs is important. There are 3 distinct immune architectures described based on the amount and locations of TILs, namely immune enriched (IN), immune excluded (IE), and immune desert (ID). Here we evaluated outcomes and characteristics associated with each immune landscape. Methods: NanoString Digital Spatial Profiling (DSP) and CosMx, a spatial multi-omics single-cell imaging platform, were performed in 75 samples from the Mayo Clinic (MC) TNBC cohort (Leon-Ferre BCRT 2018). NanoString IO360 was performed in 114 samples from the FinXX trial ( NCT00114816) . Firstly, tumors with sTIL quantified by H&E ≤ 30% were classified as ID. The rest of the tumors with high sTIL &gt; 30% were categorized according to the intratumoral CD8 protein expression by DSP, with IE having intratumoral CD8 in the lower median and IN having intratumoral CD8 in the upper median. Chi-square test, gene set enrichment, Cox regression, and Kaplan-Meier analysis were used. Differential expression listed as log 2-fold change (FC) was estimated from the linear mixed model with significance defined as two-sided p&lt; 0.05. Results: ID is associated with low Ki67 &lt; 5% (23.3% vs. 9.6% ID, p 0.02) as well as apocrine (11/13, 84.6%) and metaplastic histology (10/12, 83%). In both univariate and multivariate analysis, patients with IN had significantly improved recurrence-free survival (RFS) compared to those with ID (HR 0.37, 95%CI 0.18-0.74, p 0.005). Despite having high sTILs, IE had poor outcomes similar to ID (HR 0.84, 95%CI 0.36-1.98). Strikingly, we identified that IE patients had significantly lower plasmacytoid dendritic cells (pDCs) compared to IN (mean 0 vs. 0.26/100 tumor cells, 95%CI 0.08-0.43 , p 0.01). Using Gene Set Enrichment Analysis to evaluate differential hallmarks between IN and IE, we identified IF Nɑ and IFNγ (FDR &lt; 0.001) responses as significantly enriched in IN group, consistent wi th the function of pDCs, which are a subset of dendritic cells specialized in secreting high levels of type I interferon. To validate this finding, we further evaluated the 11 leading edge gene IFNɑ signature in the FinXX trial. A high IFNɑ signature score was associated with significantly improved outcomes in the FinXX trial (HR 0.21, 95%CI 0.09-0.51 , p &lt; 0.001). Similar findings were observed using Kaplan-Meier analysis in the FinXX trial with significantly improved RFS (p 0.0006) and overall survival (p 0.0001) in patients with high IFNɑ signature scores. Furthermore, we evaluated the differential gene expression unique to IN tumors in the Mayo cohort. Expressions of MHC class I and class II in tumor cells, including HLA-A, HLA-B, HLA-C, HLA-DRA, HLA-DRB1, HLA-DPA1, and HLA-E, were associated with IN and significantly improved outcomes (p &lt; 0.05) compared to ID and IE. Conclusions: Highlighting the importance of spatial context, we identified that patients with IE tumors had poor outcomes despite having high TILs. Moreover, u sing an in-depth analysis with spatially defined context, we identified the central role of pDC and the significance of IF Nɑ in TNBC. Support: Breast Cancer Research Foundation, Mayo Clinic Breast Cancer SPORE (P50CA116201-17) W81XWH-15-1-0292, P50CA015083, R35CA253187 Citation Format: Saranya Chumsri, Yi Liu, Yaohua Ma, Jodi Carter, Mark Gregory, Sarah Church, Jason Reeves, Heather Ann Brauer, Sarah Warren, Heikki Joensuu, Edith Perez, Roberto Leon-Ferre, David Hillman, Judy Boughey, James Ingle, Krishna Kalari, Fergus Couch, Matthew Goetz, Keith Knutson, E. Thompson. The spatially resolved single-cell atlas of the tumor immune architecture revealed the central role of IFN-alpha and plasmacytoid dendritic cells in triple-negative breast cancer in the Mayo Clinic cohort and FinXX trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS03-03.

Abstract Background: Tertiary lymphoid structure (TLS) is an organized form of ectopic lymphoid aggregates (LA) with secondary lymphoid organ structure. Several studies showed that the presence of TLS associates with improved outcomes in multiple cancers when treated with immune checkpoint inhibitors. However, data is currently limited regarding TLS and outcomes in HER2+ breast cancer patients (pts) treated with adjuvant trastuzumab. Furthermore, distinguishing TLS and simple LA is challenging in standard hematoxylin and eosin (H&E) staining, particularly when the germinal center is absent. Emerging studies also showed the prognostic value of MHC expression in breast cancer but mainly in triple-negative breast cancer. In this study, we evaluated integrated pathological quantification and genomic data to assess functional TLS in association with MHC expression and outcomes in the N9831 trial. Methods: Pathological evaluation of LA in H&E slides from pts treated in Arm A (chemotherapy alone) and Arm C (chemotherapy with concurrent trastuzumab) in N9831 was performed. NanoString was used to quantify mRNA of MHC class I and II expression as well as TLS-related immune genes, including IFNG, ICOSLG, CXCL13, CXCR3, BCL6, IL21R, ICOS, PDCD1, CXCR5, CXCL9, TBX21, CD38, CXCL10, CLXCL11, IL21, CD200, CD19, MS4S1. Wilcoxon rank sum test, Chi-squared test, Kaplan-Meier method, and Cox regression model were used to evaluate the association between LA and baseline characteristics, MHC expression, and outcomes. Results: LA was evaluated in 526 pts in Arm A and 485 in Arm C. Greater number of LA was significantly associated with stromal tumor-infiltrating lymphocytes (sTILs), hormone receptor negative, and higher tumor grade, but not stage and age. Using multivariable Cox regression analysis, increasing numbers of LA were associated with improved recurrence-free survival in both arms combined (RFS, p 0.028). However, when evaluating each arm separately, LA was associated with improved RFS only in Arm A (HR 0.6, 95%CI 0.43-0.84, p 0.003) but not in Arm C (HR 0.72, 95%CI 0.47-1.1, p 0.134). We further evaluated TLS-related immune genes in 252 pts in Arm C with LA ≥ 1. As a continuous variable, higher expression of BCL6 (HR 0.61, 95%CI 0.41-0.92, p 0.019) and IL21R (HR 0.78, 95%CI 0.62-0.98, p 0.03) were associated with improved RFS in Arm C pts with LA ≥ 1. However, these genes were not significantly associated with outcomes in Arm C pts without LA with BCL6 (HR1.07, 95%CI 0.67-1.71, p 0.776) and IL21R (HR 0.96, 95%CI 0.71-1.29, p 0.775). Moreover, we evaluated differential gene expression between tumors with LA ≥ 1 with high BCL6 vs. LA 0. All MHC class I and II (HLA A, B, C, E, DQ, DM, DO, DP, and DQ) were significantly higher in tumors with LA ≥ 1 with high BCL6 (p &lt; 0.001). Conclusion: A greater number of LA was associated with improved outcomes in pts with early-stage HER2+ breast cancer, particularly when treated with chemotherapy alone. Using histologic and genomic integration with the combination of pathological LA and TLS-related immune genes, we identified that pts with functional TLS with LA ≥ 1 and higher expression of BCL6 or IL21R had significantly improved outcomes when treated with trastuzumab. High MHC class I and II expressions are associated with the presence of functional TLS, underscoring the crucial role of antigen presentation in the generation of an effective adaptive immune response. Support: U10 CA180821, U10 CA180882, U24 CA196171, https://acknowledgments.alliancefound.org; Genentech; Clinicaltrials.gov Id: NCT00005970 Citation Format: Saranya Chumsri, Tracy Shachner, Zhuo Li, Nadine Norton, Alvaro Moreno-Aspitia, Gerardo Colon-Otero, Edith Perez, Aziza Nassar, E. Thompson, Keith Knutson. MHC Class I and II Expression, Functional Tertiary Lymphoid Structure (TLS), and Outcomes in Early-Stage HER2-Positive (HER2+) Breast Cancer in NCCTG N9831 (Alliance) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-25-04.

Abstract Introduction Despite progress in MBC, too many continue to succumb due to treatment resistance or intolerance. SV-BR-1-GM is an allogenic human breast cancer cell line with antigen presenting cell activity designed to overcome the immune-suppressive tumor microenvironment while being acceptable to extensively pretreated contemporary MBC patients. We report interim exploratory analysis of the ongoing RCT of the Bria-IMT regimens. Methods An interim exploratory analysis using preliminary partially available evaluable data of the ongoing prospective, randomized phase 2 (NCT03328026; 2018-present) of Bria-IMT (irradiated SV-BR-1-GM) with a PD-1check point inhibitor (CPI) every 3 weeks (25 patients dosed to date). Both regimens include cyclophosphamide 300 mg/m2 48-72 hours prior to intradermal Bria-IMT (~20 x 106 cells) followed by interferon-alpha at the inoculation sites 2 days later. The control arm used the original sequence with simultaneous start of Bria-IMT and CPI in cycle 1. The experimental arm started CPI in cycle 2 after the 2nd inoculation. Candida skin test was performed before cycle 1 to determine anergy status while delayed-type hypersensitivity skin test (DTH), defined as &gt;5mm erythema & induration, was done at every cycle by intradermal injection of a small test dose of Bria-IMT prior to full dose inoculation. Results Median age: 58 (range 37-81); median prior therapies: 8 lines (range 4-18); 89% were grade 2/3 (n=18); 68% hormone receptor positive; 61% HER2 negative, 33% HER2 low, and 6% HER2 high; 33% triple negative. Overall, 53% of subjects had a clinical benefit as best response by BICR, PI or target lesion measurement. The two treatment arms were similar with a trend showing longer median durations on therapy (mDOT) of 3.7 mo in the experimental delayed CPI arm compared with mDOT = 2.9 for original sequence control arm. 47% of patients were anergic to candida. Among all anergic subjects, the mDOT was 3.5 compared to 2.5 mo for non-anergic patients. However, among anergic subjects, the alternative treatment arm had a lower risk of treatment discontinuation (improved HR) with mDOT of 3.7 compared to the 3.3 mo mDOT of the original treatment. 50% of anergic subjects eventually developed DTH to SV-BR-1-GM. mDOT was 4.0 mo for DTH+ pts vs 3.0 mo for those who did not mount DTH. Median OS was not yet reached; mean OS was higher in non-anergic vs anergic pts. Among those who developed an inoculation site reaction to Bria-IMT, OS was greater than for those who did not. Time on the Bria-IMT regimen exceeded the time on penultimate treatment in 22% of subjects while 33% of subjects with prior CPI use exceeded last therapy. AEs were mild with 28% of subjects (n=7) having &gt; grade 3 events. The most common grade 3+ AE was lipase increase (n=3). One subject with encouraging changes in peripheral blood tumor markers and CTCs completed a PET study using Zr-89 crefmirlimab berdoxam, a zirconium-89 labelled truncated antibody specific to human CD8α (CD8 Immuno-PET) and demonstrated increased uptake in some metastatic lesions and draining lymph nodes. Updated results will be provided at the meeting. Conclusion Sequencing of CPI with Bria-IMT is associated with differential clinical outcome trends but not statistically significant in this interim preliminary exploratory analysis regardless of prior CPI use. Bria-IMT is immunogenic with clinical benefit demonstrated for both treatment schedules among patients with inducible DTH reactions. Patients who develop an immune response to Bria-IMT had an increase in OS compared to those who did not. The nodal localization of CD8+ cells on PET may indicate a systemic activation of CD8 positive lymphoid cells. It also provides support that the Bria-IMT + CPI combination immune-based therapy can result in an increase of CD8+ tumor infiltrating lymphocytes in breast cancer metastatic sites. These preliminary results will be evaluated in the ongoing randomized phase 3 pivotal registrational trial. Citation Format: Carmen Calfa, Chaitali Nangia, Minal Barve, John Knecht, Jarrod Holmes, Kendrith Roland, Ralph Boccia, Frances Valdes-Albini, Zach Gostout, Mingjin Chang, William Williams, Charles Wiseman, Bonnie Guerin, Shaker Dakhil, Giuseppe Del Priore, Saranya Chumsri. Randomized Phase 2 of Bria-IMT, an Allogenic Human Cell Line with Antigen Presenting Activity, in Heavily Pretreated Metastatic Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-05-12.

Abstract Background: Post-menopausal women with estrogen receptor positive breast cancer (BC) are typically prescribed endocrine therapy with an aromatase inhibitor (AI) for 5-10 years following BC diagnosis. AIs have multiple established side effects related to estrogen deprivation including vasomotor symptoms, vaginal dryness, and accelerated bone thinning. Many patients also complain about the impact of AIs on skin quality; however, limited data currently exists, particularly with objective measurements of skin quality. Canfield Sciences VISIA-CA is a device that can be used to objectively measure skin changes using patented comparison to norms analysis with a skin feature database to grade the skin relative to others in the same age and skin type. Herein, we aim to evaluate changes in skin quality with the Canfield Sciences VISIA-CA Device after initiation of AI therapy and investigate potential benefits of skincare intervention. Trial Design: This is a pilot study aiming to describe changes in skin quality after initiation of AI therapy in BC survivors through use of VISIA-CA technology and patient reported outcome measures. This study will allow us to collect data and identify the trend (if any) for a future larger study. Patients who consent for participation are given a baseline survey to assess self-reported quality of life, perception of skin quality, and self-image prior to initiation of AI. Patients also receive baseline skin measurement with the VISIA-CA device and facial skin photography. Baseline skincare regimen is documented. Any patients on prescription tretinoin products at time of baseline assessment are excluded from the study. Patients return 6 months after initiation of AI for follow-up surveys, updated VISIA-CA measurement, and facial skin photography. Patients then meet with a Mayo Clinic Cosmetic Center aesthetician for skincare intervention with recommended topical treatments including daily facial cleanser, exfoliator, toner, hydrating crème, and retinol-based product. Patients return for additional visits with updated survey, VISIA-CA measurement, and facial skin photography at 1 month, 3 months, and 6 months after skincare intervention. Patients are asked to complete skincare compliance diary to document adherence on a weekly basis. Eligibility Criteria: Post-menopausal patients with newly diagnosed ER-positive BC at Mayo Clinic Florida are identified for participation in the study prior to beginning AI therapy. Specific Aims: 1.) Evaluate the incidence and severity of skin changes after initiation of AI therapy in BC survivors through use of Canfield Sciences VISIA-CA technology, facial skin photography, and validated patient reported outcome measures. 2.) Assess for objective improvements in skin quality measurements after skincare intervention including a retinol-based product Statistical Methods: Continuous variables will be summarized as mean (standard deviation) or median (range) and categorical variables will be reported as frequency (percentage). The changes of skin measurement and patient reported outcome measurements will be calculated and summarized for the following time frames: 1) from initiation of AI therapy to 26 weeks after 2) from the initiation of skincare intervention and 4 weeks, 12 weeks, and 26 weeks after. Appropriate statistical plots will be used to illustrate the change. Target Accrual: 50 patients. Schedule of Events Citation Format: Lauren Cornell, Leila Tolaymat, Pooja Advani, Saranya Chumsri, Pincelli Thais. Enhancing skin appearance and quality of life in breast cancer survivors on aromatase inhibitor therapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-19-12.

Abstract Background: Activation of the RAS/MAPK pathway is associated with reduced tumor-infiltrating lymphocytes and poor outcomes in triple-negative breast cancer (TNBC). This trial evaluated the efficacy of pembrolizumab in combination with binimetinib, a MEK inhibitor. Methods: Patients with unresectable locally advanced or metastatic TNBC with ≤ 3 prior lines of therapy were enrolled. Treatment includes a 2-week run-in with binimetinib followed by pembrolizumab. There were 2 dose levels (DL) with binimetinib at 45 mg at DL 0 and 30 mg at DL -1. A standard 3+3 design was used in Phase I, and Simon’s two-stage Optimal design was used in Phase II. PD-L1 22C3 was performed in archival samples with CPS ≥ 10 considered as positive (PD-L1+). Tumor-infiltrating lymphocytes (TILs) were quantified into 0, 1, 2, and 3+. Circulating tumor cells (CTC) and circulating cancer-associated macrophage-like cells (CAML) were isolated using CellSieve microfilters and immunofluorescently labeled with PD-L1 and p-ERK. Wilcoxon rank sum test, Chi-square test, Cox regression model, and Spearman correlation were used for analysis. Results: 22 patients were enrolled with a median age of 58 years old. Dose-limiting toxicity (DLT) was observed in 2 out of 4 patients in DL 0, with grade 3 ALT abnormality, flank pain, and nausea. In the next 6 patients in DL -1, there was 1 DLT with grade 3 AST/ALT abnormality. There were 17 patients treated with DL -1 and were evaluable for response. The objective response rate (ORR) was 29.41% (95% CI: 10.31-55.9) with 1 complete response (CR) and 4 partial responses (PR). The clinical benefit rate (CBR ≥ 24 weeks) was 35.29% (95% CI: 14.21-61.67). ORR in patients without liver metastases was 55.56% (95% CI: 21.20 - 86.30) and CBR was 66.67% (95% CI: 29.93-92.51). No response was observed in all 5 patients with liver metastases. There were 40.9% of patients with PD-L1 CPS ≥ 10. ORR in patients with PD-L1+ was 80%. However, 11.1% of patients with PD-L1 negative tumors also had an objective response and 44.4% of patients had clinical benefit ≥ 24 weeks. PD-L1 expression in archival tissue was associated with ORR (p 0.032) but not CBR (p 0.198), progression-free survival (PFS, p 0.373), and overall survival (p 0.348). TILs in archival tissue were also not associated with CBR (p 0.155) and PFS (p 0.157). One patient with TILs 0 had a stable disease ≥ 24 weeks and 2 patients TILs 1+ also had an objective response. We further evaluated blood-based biomarkers with CTC and CAML. Baseline PD-L1 in CAML (p 0.04) and decline in CAML size (p 0.02) after 1 cycle was significantly associated with CBR. However, baseline CTC count, CAML count (p 0.64), CAML size (p 0.46), p-ERK in CAML (p 0.23), and changes in CTC count, CAML count (p 0.83), p-ERK (p 0.07), and PD-L1 (p 0.08) in CAML were not significantly associated with responses. Using Cox regression analysis, a reduction in CAML count (p 0.02), CAML size (p 0.01), and PD-L1 in CAML (p 0.03) were associated with significant improvement in overall survival but not the reduction in p-ERK (p 0.6). However, PD-L1 expression in CAML is not associated with PD-L1 expression in archival tissue (Spearman correlation 0.13). Conclusions: Pembrolizumab and binimetinib at 30 mg are safe with manageable toxicities. Consistent with the preclinical data that MEKi can restore T cell function, promising activity was observed even in patients with low TILs and PD-L1 negative, particularly in patients without liver metastases. PD-L1 expression in peripheral blood CAML rather than archival tumor tissue may serve as a better biomarker to predict the clinical benefit of this combination. Early reductions in CAML count and size, were also significantly associated with responses. Future larger clinical trials are warranted to further evaluate the efficacy of this chemotherapy-free combination. Citation Format: Saranya Chumsri, Joseph Larson, Daniel Adams, Kathleen Tenner, Cha-Mei Tang, Morgan Weidner, Amanda Arnold, Dana Haley, Pooja Advani, Kostandinos Sideras, Alvaro Moreno-Aspitia, Edith Perez, Keith Knutson. Phase I/II study of pembrolizumab in combination with oral binimetinib in patients with unresectable locally advanced or metastatic triple-negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-06-14.

Abstract Background: Taxane based chemotherapy (chemo) forms a critical part of breast cancer (BC) treatment in early and metastatic settings. Taxanes can cause peripheral neuropathy (CIPN)-sensory and motor, primarily of the hands and feet, resulting in quality of life decline and negaive impact on BC survival. Acral cryotherapy has shown benefit in reducing in in minimizing the incidence and severity ofcidence and severity of CIPN. However, these studies have included limited number of patients (pts) with inconclusive evidence to change US practice guidelines, have been primarily conducted in Asia, and did not include racially diverse patients. Methods: We conducted a single arm non randomized study at Mayo Clinic that included early BC pts who underwent standard of care paclitaxel or docetaxel based chemo. Pts had ECOG performance status 0-2, no sensory peripheral neuropathy at study entry and were able to give signed informed consent. Pts with metastatic BC, Raynaud's and peripheral vascular disease, cryoglobulinemia, cold intolerance, prior exposure to neurotoxic or taxane chemotherapy were excluded. Participating pts wore frozen gloves and socks (−20 to −10°C) on both hands and feet, 15 min before, during and until 15 min post taxane infusion. During chemo, grade (G) of CIPN (sensory) per CTCAE v5 was collected prior to each cycle of chemo, end of and 3 months after chemo. Schedule of events is listed in Table 1. Continuous variables were summarized using mean and standard deviation, and categorical variables were summarized with number and percentage of patients. Numeric variables were compared with t tests (paired and unpaired), and categorical variables were compared with Chi-Squared test for independent data and Mcnemar’s test for dependent data. All statistical tests were two-sided and were performed using R Statistical Software (version 4.1.2; R Foundation for Statistical Computing). Results: A total of 95 patients were included in this study. Median age is 54 years, 66.3% pts were White (W), 23.2% African American (AA), 4.2% Asian (A) and 4.2% Hispanic (H). Median BMI was 27.7. Most pts had stage I/II (75.8%), ER positive (64.9%) and HER2 negative (55.3%) BC and got adjuvant chemo (52.6%). Only 10.6% pts had diabetes, 55.3% used alcohol. Vitamin D3 use seen in 65.6%, B12 in 6.2% and folate, B12 and D3 in 6.2% pts. A total of 41 pts (44.1%) developed neuropathy at some point during chemo, of which 27 pts were W (43%), 10 pts AA (45%), 2 pts H, 1 Asian and 1 other. CIPN was G1 in 37 pts (90%). G2 CIPN was seen in 4 pts, at or after cycle 10 of weekly paclitaxel. Cold intolerance was seen in 24 pts (25%), G1 in 20 and G2 in 4 pts, all seen in cycle 1 with 1 pt withdrawal. Recovery to G0 was seen in 15 W pts at chemo end and 2 additional pts at 3 month after chemo. None of the AA pts, one H and one A pt had CIPN recovery to G0. In 4 AA pts who had G1 CIPN during chemo, G2 CIPN was noted at 3 month follow up. No Statistically significant differences in baseline characteristics and neuropathy results for W vs nonwhites (NW) were seen except Charleson score (p-value 0.023). Conclusion: Acral cryotherapy was found to be effective in reducing the incidence and severity of CIPN from taxane in our study. This is the only study with diverse racial/ethinic pt inclusion and incidence of CIPN was similar in W and NW. However, majority of G2 CIPN pts were AA and recovery to G0 CIPN was not seen in AA pts. Majority (63%) of W pts recovered to G0 at end of follow up. Analysis of objective testing of all pts is underway. Continued research into risk factors for AA pts to develop CIPN and its mitigation are warranted. XX XX Citation Format: Pooja Advani, Jinky Harvey, Ivy Vilches, Alex Hochwald, David Hodge, Amanda Arnold, Morgan Weidner, Dana Haley, Tanmayi Pai, Saranya Chumsri, Rohit Rao, Kostandinos Sideras, Cindy Tofthagen, Alvaro Moreno-Aspitia. Cryotherapy to Prevent Taxane-Induced Sensory Neuropathy of the Hands and Feet [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-12-10.