Chumsri, Saranya

Abstract Background The current definition, prognosis, and optimal treatment (tx) for oligometastatic breast cancer (OMBC) are not fully known. With advances in multimodality breast cancer (BC) tx and overall improvement in patient (pt) outcomes, it is important to identify baseline pt factors that confer better prognosis in OMBC and assess the impact of local/regional tx and metastasis (mets)-directed tx on survival outcomes. Methods We reviewed 105 Mayo Clinic pts with OMBC (up to 5 mets) from 2003 to 2021. Pts were excluded from analysis if they were misidentified as having OMBC (n=6), did not have a primary breast mass (n=1), developed de novo BC during tx (n=1), or were lost to follow up (n=2). Categorical variables were summarized as counts. Continuous variables were reported as medians. Kaplan-Meier method was used to estimate survival and the time from diagnosis to next tx at 1, 3, and 5 years. Log-rank test was used to compare survival rates between baseline factors. Univariate Cox proportional hazards models were performed on both baseline and time-dependent factors. All tests were two-sided with p-value < 0.05 considered statistically significant. Results Total pts included were 95. Median age was 49 (range, 26-86), most (93.6%) pts were White, and 46.8% were postmenopausal. Invasive ductal carcinoma (89.5%) was the most common BC type. Median survival was 10.8 years; 1-, 3-, and 5-year survival rates were 98.9%, 87.7%, and 81%, respectively. 58 pts (61.1%) required a change in tx due to disease progression. No significant survival difference was observed in pre- vs. postmenopausal pts (p=0.71) or in groups based on hormone receptor and/or human epidermal growth factor receptor 2 status. 47 pts (49.5%) received local/regional tx; no significant difference in survival (HR 0.57, 95% CI 0.23-1.40; p=0.217) or time to next tx (HR 0.67, 95% CI 0.39-1.15; p=0.144) was seen in this subgroup. Of these pts, 36 (76.6%) received neoadjuvant chemotherapy and/or immunotherapy, 5 of whom (10.6%) also started endocrine tx preoperatively. Overall, 11/47 pts (23.4%) received neoadjuvant endocrine tx. 20 pts received systemic tx without eventual surgery, and 5 pts got palliative radiation (RT). Biopsy-confirmed mets were noted in 76 pts (80%), with bone-only mets in 50%, 30 pts (31.6%) with viscera-only mets and 7 pts (7.4%) with both bone and visceral mets. 18 pts had suspected mets on imaging but did not undergo biopsy. The hazard of death was 6.34 times higher in pts with both bone and visceral mets than those with bone-only mets (p=0.008). Pts with viscera-only mets had higher survival at 2 and 3 years than pts with bone-only or both bone and visceral mets (p=0.093). Pts with 3 mets (7/76, 7.4%) had decreased survival at 1, 2, and 3 years compared to pts with 1-2 (65/76, 85.5%) mets (p=0.6). 67 pts (70.5%) received mets-directed tx; RT alone was the most common modality (52/67, 77.6%), followed by surgery (6/67, 9%), RT plus surgery (5/67, 7.5%), and ablation alone (3/67, 4.5%). There was no significant difference in survival (HR 1.27, 95% CI (0.53, 3.07), p=0.589) or time to next tx (HR 0.95, 95% CI (0.56, 1.63), p=0.856) in pts who received mets-directed tx. Multivariate analysis was not performed because most findings were not statistically significant in univariate analysis. Conclusions We did not find any significant differences in survival based on characteristics like menopausal status or site or number of mets in pts with OMBC. There was a trend toward improved survival in pts with viscera-only mets, but this finding requires validation. Local/regional and mets-directed tx did not improve survival; however, survival at 1, 3, and 5 years was excellent in this OMBC pt population. Our study was limited by low pt numbers and heterogeneity in the pt population. Findings need validation in larger studies. Citation Format: Tanmayi Pai, Raza Zarrar, Zhongwei Peng, Zhuo Li, Lauren Cornell, Kostandinos Sideras, Rohit Rao, Alvaro Moreno-Aspitia, Saranya Chumsri, Sarah McLaughlin, James Jakub, Emmanuel gabriel, Sanjay Bagaria, Laura Vallow, Santo Maimone, Pooja Advani. Clinical Features and Survival Outcomes of Oligometastatic Breast Cancer Patients: The Mayo Clinic Experience [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 PO3-06-04.

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 > 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 > 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.

Abstract Background: Circulating tumor cell clusters (CTCCs) are aggregated groups of tumor cells that detached from primary tumors and circulate the bloodstream. However, while Circulating Tumor Cells (CTCs) are a well studied phenomenon, CTCCs remain relatively unexplored and ill-defined, with only a few descriptive investigations evaluating their clinical utility. Adding to CTCC complexity is that various subtypes exist, including homotypic clusters consisting of a homogenous population of tumor cells and heterotypic CTCCs made of CTCs with immune/stromal white blood cells (WBCs). Furthermore, CTCs can undergo Epithelial-Mesenchymal Transition (EMT), a process characterized by loss of epithelial traits and upregulation of mesenchymal traits, and can form clustered EMTs (CEMTs). Moreover, CTCs can fuse with macrophages forming Tumor Macrophage Hybrid Cells, aka Cancer-Associated Macrophage Like cells (CAMLs) when in circulation. We enumerated all these types of cells and complex aggregates in the peripheral blood of patients with metastatic breast cancer (mBC). Methods: We enumerated the 6 populations from patient samples enrolled in IRB aproved prospective pilot studies. Whole peripheral blood (7.5mL) was filtered and stained with cytokeratin (CK) & CD45/CD14 to identify CTCs. CTCs were defined as an intact DAPI nuclei and strong filamentous CK. Homotypic CTCCs were defined as ≥2 CTCs attached together. Heterotypic CTCCs were defined as ≥1 CTC attached to ≥1 WBC. EMTs were defined as having DAPI nuclei and weak non-filamentous CK. CEMTS were defined as ≥2 EMTs. CAMLs were defined as having an enlarged polynucleated DAPI, and positive for CD45/CD14 or non-filamentous CK. Median progression free survival (mPFS) and median overall survival (mOS) over 24 months (m) were evaluated. Results: We evaluated the blood of 79 mBC patients. Single CTCs were found in 57% of patients (n=34/79), homotypic CTCCs 15% (n=12/79), heterotypic CTCCs 66% (n=27/79), EMTs 56% (n=44/79), CEMTs 23% (n=18/79) and CAMLs 97% (n=77/79). Over 24 ms, patierns with detectable heterotypic CTCCs & homotypic CTCCs had the shortest response times at mPFS=2.8 & mOS=5.8 ms, or mPFS=2.1 & mOS=4.3 ms, respectively. This was followed by CTCs mPFS=3.7 & mOS=13.7 ms, EMTs mPFS=4.3 & mOS=14.4 ms, CAMLs mPFS=4.3 & mOS=14.4 ms, and CEMT mPFS=4.7 & mOS=13.2 ms. Additionally, CTCCs were rare in HER2+ patients at 4.4% (n=1/23), but no associations to other hormone statuses were found. Conclusion: CTCCs appear to represent an array of subtypes with different biological and clinical meanings. Here we enumerated CTCC subtypes in the blood of mBC patients and stratified the various types to clinical outcomes. These data suggest CTCCs are clinically important and further understanding of their biology in the context of tumor pathogenesis is needed. Citation Format: Daniel L. Adams, Carolina Reduzzi, Aravind Aryasomayajula, R. Katherine Alpaugh, Saranya Chumsri, Cha-Mei Tang, Giuseppe Del Priore, William V. Williams, Massimo Cristofanilli. Identifying and stratifying circulating tumor cell cluster subtypes in metastatic breast cancer patients and evaluating their clinical outcomes [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 2303.

Abstract Background: Residual disease after neoadjuvant chemotherapy (NAC) in breast cancer (BC) confers poor outcomes. Trastuzumab emtansine (T-DM1) is approved for HER2+ patients with residual disease after NAC. However, many patients still develop recurrence. H2NVAC is a multi-epitope CD4 helper T cell activating vaccine that includes a pool 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. Method: We conducted a safety run-in phase of H2NVAC in combination with T-DM1 in stage II-III HER2+ BC with residual disease after NAC. 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 toxicity occurring within 21 days after the first vaccination. Results: 20 patients were enrolled (median age 51; 27-69 years), including 80% White and 15% Black. 90% had hormone receptor-positive disease. There was no DLT observed in the safety run-in cohort. All adverse events (AEs) during the DLT period were grades 1 and 2, with fatigue being the most common (60% G1, 5% G2), followed by peripheral sensory neuropathy (55% G1, 5% G2), and injection site reaction (50% G1). Across all treatment cycles, the 10 most common AEs that were at least possibly related to treatment in all cycles are summarized in the table below. The injection site reaction was the most common AE, with 85% G1 and 15% G2. Conclusion: H2NVAC, in combination with T-DM1, was safe, with a favorable side effect profile. There was no DLT observed. The most common AE was injection site reaction, with the majority being G1. A multicenter, randomized, placebo-controlled, phase II trial of H2NVAC vs. placebo in combination with trastuzumab emtansine is currently ongoing through the ACCRU consortium (NCT04197687). Adverse Events Grades 1 2 N % N % Injection site reaction 17 85.0 3 15.0 Aspartate aminotransferase increase 13 65.0 Alanine aminotransferase increase 9 45.0 Fatigue 7 35.0 2 10.0 Peripheral sensory neuropathy 7 35.0 2 10.0 Alkaline phosphatase increase 8 40.0 Nausea 7 35.0 1 5.0 Arthralgia 7 35.0 Myalgia 5 25.0 1 5.0 Platelet count decrease 6 30.0 Citation Format: Saranya Chumsri, Sharmila Giri, Andy J. Ness, David W. Hillman, Nadine Norton, Davitte Cogen, Brian M. Necela, Aziza Nassar, Donald W. Northfelt, Pooja Advani, Rohit Rao, Kostandinos Sideras, Alvaro Moreno-Aspitia, Brenda J. Ernst, Kathryn J. Ruddy, Matthew P. Goetz, Keith L. Knutson. Safety and tolerability of multi-epitope HER2 peptide vaccines in combination with trastuzumab emtansine in HER2-positive breast cancer patients with residual disease after neoadjuvant chemotherapy [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 5005.

Abstract Background: Previous studies demonstrated that obesity is associated with poor outcomes and significantly worse pathological complete response (pCR) in triple-negative breast cancer (TNBC) treated with conventional chemotherapy. Emerging studies described a phenomenon termed the obesity paradox, which referred to improved outcomes observed in obese patients treated with immune checkpoint inhibitors (ICIs). Our study aimed to determine distinct immune features in TNBC across body mass index (BMI). Methods: Characteristics and outcomes of TNBC patients treated with neoadjuvant pembrolizumab-based chemotherapy at Mayo Clinic were collected. Normal BMI was defined as 18-25 kg/m2, overweight 25-30, and obese BMI ≥ 30. NanoString CosMx, a spatial multi-omics single-cell imaging (SMI), was performed in 75 samples from the Mayo Clinic TNBC cohort (Leon-Ferre BCRT 2018). Differential expression as log 2-fold change (FC) was estimated from the linear mixed model with significance defined as two-sided p< 0.05. Results: Between 2021-2023, there were 108 TNBC patients treated with neoadjuvant pembrolizumab. 25.9% were obese, 32.4% were overweight, and 41.7% had normal BMI. In contrast to previous studies with conventional chemotherapy, obese patients numerically had a higher pCR rate of 71.4% with pembrolizumab-based chemotherapy compared to 55.6% in normal and 62.9% in overweight patients. However, this difference did not reach statistical significance (obese vs. normal weight, OR 2.26, 95%CI 0.89-6.06, p 0.094). We further evaluated spatially-resolved immune features associated with obesity using CosMx SMI in 75 samples from the MC TNBC cohort. Obese patients had significantly higher intratumoral B cells (log2FC 1.88, p 0.017), stromal B cells (log2FC 2.79, p 0.001), stromal plasmablasts (log2FC 1.94, p 0.047), and stromal macrophages (log2FC 1.80, p 0.017) compared to patients with normal BMI. Obese patients also had significantly lower intratumoral myeloid dendritic cells (mDC) (log2FC -1.27, p 0.037). Similar trends were observed after standardizing cell counts per 100 tumor or stromal cells, including higher intratumoral B cells (log2FC 3.00, p 0.001), intratumoral plasmablasts (log2FC 2.00, p 0.006), intratumoral natural killer (NK) cells (log2FC 1.66, p 0.044), and stromal B cells (log2FC 1.50, p 0.008). Differential gene analyses for intratumoral B cells revealed that genes (CD74, HLA-C, HLA-DRB1, HLA-DRA, HLA-DRB) associated with the positive regulation of type 2 immune or chemokine response were upregulated. Conclusions: Using in-depth analysis with spatially defined context, our study showed that obese TNBC patients had significantly higher B cell infiltration, which is associated with improved outcomes with ICIs. Future research on how obesity alters the immune microenvironment is needed to identify potential pathways to improve outcomes with ICIs in TNBC. Citation Format: Songhan Pang, Yi Liu, Yaohua Ma, Zhuo Li, Roberto A. Leon-Ferre, David Zahrieh, David W. Hillman, Judy C. Boughey, James N. Ingle, Krishna R. Kalari, Fergus J. Couch, Matthew P. Goetz, Keith L. Knutson, Saranya Chumsri, E. Aubrey Thompson. Tumor-immune microenvironment associated with obesity in triple-negative breast cancer in the Mayo Clinic cohort [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 1162.

Abstract Background: Recently, it was described that macrophages and tumor cells can fuse to form tumor macrophage fusion cells (TMFs) which are detectable within primary tumors and patient’s (pts) circulation. However, there are multiple pathways and subsequent subtypes of TMFs, with limited data on the various TMF types, commonality in blood, and clinical relevance. Here we evaluated n=120 metastatic breast cancer (mBC) blood samples for CTCs & TMFs. We describe numerous types of TMFs with vastly different fusion phenotypes, including partial (i.e. some membrane interaction & both cells retaining their original phenotypes), homodimeric (i.e. both cells with fused membranes & sharing cytoplasm), cannibalistic (i.e. CTC within a CD14+ macrophage & cells retaining their individual phenotypes), binucleated (i.e. both cells completely merge & becoming one cell with dual expression phenotypes), and hyperploidy (i.e. multiple cells merge to form a large polyploid cell). As CTCs & TMFs are isolated in conjunction from a single blood sample, we evaluated both CTCs & all TMF subtypes to determine their prognostic and predictive values for aggressiveness of disease. Methods: We categorized and enumerated the 5 forms of TMFs from a prospective pilot study using n=120 mBC pts that were starting new lines of treatment. Whole peripheral blood (7.5mL) was procured, filtered and stained using cytokeratin & CD45/CD14 to identify CTCs & TMFs. We compared the presence of the various types of TMFs & CTCs to pt’s progression-free survival (PFS) and overall survival (OS) hazard ratios (HRs), analyzed by censored univariate analysis based on RECIST v1.1 over 24 months. Results: CTCs were found in 39% (n=47/120), with partial fusion TMFs in 26% (n=31/120), homodimeric 2% (n=2/120), cannibalistic 0% (n=0/120), binucleated 2% (n=2/120), hyperploidy 93% (n=113/120). Presence of CTCs alone, binucleated, or hyperploidy TMFs were not prognostic for PFS (p=0.0988, p=0.4120, & p=0.7615 respectively), or OS (p=0.2015, p=0.0845, p=0.1121 respectively). However, TMFs with partial or homodimeric fusion were prognostic for worse PFS (HR=2.2, p=0.0063 and HR=6.0, p=0.0305, respectively) and for worse OS (HR=2.8, p=0.0037 and HR=8.8, p=0.0271, respectively). Furthermore, combining pts with any TMFs into one group, minus hyperploidy, was highly significant for worse PFS (HR=2.9, 95%CI 1.7-5.0, p=0.0002) and worse OS (HR=3.8, 95%CI 2.0-7.5, p=0.0002), though certain subtypes of hyperploidy were also indicative of worse outcomes. Conclusion: The study of TMFs is relativity limited and their existence is new in oncology. Here we detected and described TMFs in the blood of mBC pts while demonstrating an association with poor clinical outcomes. These data suggest TMF involvement in the pathogenic cascade of cancer and further understanding of their biology may be important in the study of tumorigenesis. Citation Format: Daniel L. Adams, R. Katherine Alpaugh, Rena G. Lapidus, Saranya Chumsri, Carolina Reduzzi, Kirby P. Gardner, Cha-Mei Tang, Giuseppe Del Priore, William V. Williams, Massimo Cristofanilli. Tumor macrophage fusion cells detected in the circulation of metastatic breast cancer patients is prognostic for rapid progression and death [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 2310.