Factors Predictive of Positive Lymph Nodes for Breast Cancer

BACKGROUND

Axillary node status is an important prognostic factor in breast cancer. The primary aim was to evaluate tumor size and other characteristics relative to axillary disease.

MATERIALS AND METHODS

Single institution retrospective chart review of stage I-III breast cancer patients collected demographic and clinical/pathologic data from 1998-2019. Student's t-test, Chi-squared test (or Fisher exact test if applicable), and logistic regression models were used for testing the association of pN+ to predictive variables.

RESULTS

Of 728 patients (mean age 59 yrs) with mean follow up of 50 months, 86% were estrogen receptor +, 10% Her2+, 78% ER+HER2-negative, and 10% triple-negative. In total, 351/728 (48.2%) were pN+ and mean tumor size was larger in pN+ cases compared to pN- cases (mean = 27.7 mm versus 15.5 mm) (p < 0.001). By univariate analysis, pN+ was associated with lymphovascular invasion (LVI), higher grade, Her2, and histology (p < 0.005). Tumor-to-nipple distance was shorter in pN+ compared to pN- (45 mm v. 62 mm; p< 0.001). Age < 60, LVI, recurrence, mastectomy, larger tumor size, and shorter tumor-nipple distance were associated with 3+ positive nodes (p < 0.05).

CONCLUSIONS

Larger tumor size and shorter tumor-nipple distance were associated with higher lymph node positivity. Age less than 60, LVI, recurrence, mastectomy, larger tumor size, and shorter tumor-nipple distance were all associated with 3+ positive lymph nodes.

Surgeon and Radiologist Evaluation of Electromagnetic Chip Localization for Benign and Malignant Breast Lesions

BACKGROUND

SmartClipTM is a food and drug administration-approved, electromagnetic chip (EMC) localization system that provides three-dimensional navigation for the excision of soft tissue lesions. The purpose of this study was to analyze the accuracy and feasibility of EMC radiologic and surgical localization for benign and malignant breast lesions.

PATIENTS AND METHODS

An institutional review board-approved, single institution, prospective study from October 2020 to September 2022 of 38 women undergoing breast conserving surgery with EMC localization of a single lesion > 5 mm on mammogram (MMG) or ultrasound (US) imaging. Surveys from performing breast radiologists and breast surgeons were collected after image-guided localization and surgical excision.

RESULTS

Seventy-six survey responses from nine radiologists and four surgeons were received. The deployment needle and EMC were highly visible in 86.8% and 76.3% of procedures, respectively. There was no difficulty in deployment for 92.1% of procedures. The EMC was in the correct location on postdeployment MMG in 97.4% of cases. Three instances of EMC migration occurred, one 1 cm from target lesion. The targeted mass and EMC were within the surgical specimen in 97.4% of cases. On specimen radiograph, 39.5% of the EMCs were 0-1 mm from the center of the target lesion, 18.4% were within 2-4 mm, and 23.7% were within 5-10 mm. Mean operating room time for all cases was 65 min. One case required US to localize the target due to console malfunction.

CONCLUSION

There was successful EMC deployment by radiologists with accurate visualization and successful surgical excision in most cases. The EnVisioTM SmartClipTM system is a reproducible and accurate localization method for benign and malignant breast lesions.

Limitations in the Application of Clinicopathologic Factors Alone in Predicting Radiation Benefit for Women with Low-Risk DCIS after Breast Conserving Surgery: The Impact of a 7-Gene Biosignature Based on 10-Year Ipsilateral Breast Recurrence (IBR) Rates

PURPOSE/OBJECTIVE(S)

Most women diagnosed with ductal carcinoma in situ (DCIS) receive radiotherapy (RT) after breast conserving surgery (BCS); however, clinical trials show that over 70% of women with BCS alone will not have a recurrence and therefore not benefit from RT. Traditionally, clinicopathologic (CP) factors have been used to select for whom to de-escalate treatment, but prospective trials have failed to identify a low risk CP group that did not benefit from RT with respect to local control. This study assessed the re-classification of patients with low-risk CP into Risk groups defined by the 7-gene biosignature and compared to 10-yr IBR rates.

MATERIALS/METHODS

Women (n = 926) from four international DCIS cohorts treated with BCS had formalin-fixed paraffin embedded tissue samples analyzed at a CLIA lab (Laguna Hills, CA). CP low-risk patients were identified using a) RTOG-9804-like criteria [Nuclear Grade 1 or 2 & Size ≤2.5 cm & non-Palpable & Screen Detected & margin negative (no-ink on tumor)] and b) MSKCC-like criteria [low-risk score<220, determined using nomogram weighted factors (excluding: number of re-excisions and RT treatment), and using no-ink-on-tumor instead of close margin]. The 7-gene DCIS biosignature combined biomarkers with CP factors (age, size, palpability, and margin status) using an algorithm reporting a Decision Score (DS) and Residual Risk subtype (RRt). Women with low-risk CP were classified into biosignature Low Risk (DS≤2.8, no RRt) or High Risk (DS>2.8 +/- RRt) groups. 10yr in-breast event (IBR) rates with and without RT were assessed by Kaplan-Meier rates and Cox proportional hazard analyses.

RESULTS

Overall, 37% of all women were classified into the biosignature Low Risk group, while 51% and 34% were classified into CP low-risk groups (RTOG-9804-like, MSKCC-like, respectively). The biosignature Low Risk group (n = 338) had a 10-yr IBR risk of 5.6% after BCS and no significant RT benefit (absolute RT benefit = 0.8%, p = 0.70), 99% negative predictive value (NPV) for RT benefit. CP low-risk groups had 10-yr IBR rates of 12% and 8% after BCS without RT with absolute 6% (p = 0.04) and 4% (p = 0.1) IBR rate reductions with RT. The biosignature reclassified 51% and 63% of CP low-risk patients into the biosignature High Risk group. Importantly, these patients had higher IBR rates without RT (20% and 12%) and significant 13% (p = 0.005) and 8% (p = 0.01) absolute IBR rate reductions from RT. CP low-risk patients with concordant biosignature Low Risk demonstrated no significant RT benefit.

CONCLUSION

The 7-gene predictive biosignature more reliably identified patients with low 10-yr IBR rates and no significant RT benefit than the traditional CP low-risk criteria (RTOG-9804-like, MSKCC-like). Importantly, those CP low-risk patients who were re-classified as biosignature High Risk had increased 10-year IBR rates and significant RT benefit.

External Validation of the Breast Cancer Surgery Risk Calculator (BCSRc): A Predictive Model for Postoperative Complications

BACKGROUND

The breast cancer surgical risk calculator (BCSRc) is a prognostic tool that determines a breast cancer patient's unique risk of acute complications following each possible surgical intervention. When used in the preoperative setting, it can help to stratify patients with an increased complication risk and enhance the patient-physician informed decision-making process. The objective of this study was to externally validate the four models used in the BCSRc on a large cohort of patients who underwent breast cancer surgery.

METHODS

The BCSRc was developed by using a retrospective cohort from the National Surgical Quality Improvement Program database from 2005 to 2018. Four models were built by using logistic regression methods to predict the following composite outcomes: overall, infectious, hematologic, and internal organ complications. This study obtained a new cohort of patients from the National Surgical Quality Improvement Program by utilizing participant user files from 2019 to 2020. The area under the curve, brier score, and Hosmer-Lemeshow goodness of fit test measured model performance, accuracy, and calibration, respectively.

RESULTS

A total of 192,095 patients met inclusion criteria in the development of the BCSRc, and the validation cohort included 60,144 women. The area under the curve during external validation for each model was approximately 0.70. Accuracy, or Brier scores, were all between 0.04 and 0.003. Model calibration using the Hosmer-Lemeshow statistic found all p-values > 0.05. All of these model coefficients will be updated on the web-based BCSRc platform: www.breastcalc.org .

CONCLUSIONS

The BCSRc continues to show excellent external-validation measures. Collectively, this prognostic tool can enhance the decision-making process, help stratify patients with an increased complication risk, and improve expectant management.

Abstract 3197: Adoptive T cell therapy using IL-7 and IL-15 expanded HER2-specific CD4 T cells for metastatic breast cancer

BACKGROUND: Adoptive cell therapy (ACT) has had limited success due to low T cell infiltration in breast cancer (BC) patients. We have shown that administration of class II HER2 peptide pulsed type I polarized dendritic cell (DC1) vaccines leads to increase in CD4 T cells in the periphery of BC patients. In this study, we investigated the feasibility of expanding CD4 T cells from peripheral blood mononuclear cells (PBMC) of HER2-DC1 vaccinated BC patients.

METHODS: PBMCs from BC patients receiving HER2-DC1 vaccines were used for CD4 T cell expansion. PBMCs were co-cultured with HER2-DC1 at 10:1 ratio for initial activation followed by expansion with cytokines- IL-2 and IL-7 or IL-15. Expanded T cells were assessed for immune marker phenotyping by flow cytometry and TCRvb analysis. For TCRvB analysis, pre, post DC1, IL-7 and IL-15 expanded CD4 T cells were pelleted for DNA isolation and sequenced using Immunoseq Analyzer platform. In addition, we investigated the in vivo efficacy of adoptively transferred mouse IL-7/IL-15 expanded Her2 specific CD4 T cells in HER2+ TUBO mouse model.

RESULTS: Co-culturing of patient PBMCs with HER2-DC1 in the presence of cytokines IL-2, IL-7 and IL-15 expanded CD4 T cells ranging from 8-43 fold expansion in different samples with 92-98% CD4 phenotype. CD4 T cells expanded in IL-7 had stem like memory phenotype while IL-15 skewed to terminally differentiated CD4 T cells. IL-7 expanded T cells had significantly higher Tim3 and Ox40 expression, and effector memory proportion as compared to the IL-15 expanded T cells. Restimulation of expanded T cells with HER2 pulsed DCs showed HER2 specificity as measured by increased interferon-gamma production We identified top five clones in PBMCs from DC1-HER2 vaccinated BC patients compared to baseline. We observed differential abundance of TCR clones under IL-7 and IL-15 conditions and identified unique clones for IL-7 and IL-15. ACT using a combination of IL-7 and IL-15 expanded mouse CD4 T cells led to 50% tumor regression in HER2+ model.

CONCLUSION: These studies demonstrate that HER2 specific CD4 T cells can be successfully expanded from HER2-DC1 vaccinated patients. Post HER2 DC1 vaccine can generate a pool of antigen specific CD4 T cells and may offer a promising ACT for HER2 BC. Further studies are warranted to demonstrate the efficacy in the clinical setting.

Citation Format: Namrata Gautam, Krithika Kodumudi, Colin Snyder, Amber Beyer, Ricardo Costa, Heather Han, Brian Czerniecki. Adoptive T cell therapy using IL-7 and IL-15 expanded HER2-specific CD4 T cells for metastatic breast cancer [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 3197.

Abstract 4056: Intratumoral delivery of autologous tumor antigen specific CD4 Th1 cells combined with dendritic cells eradicates HER2 mammary carcinoma

Human epidermal growth factor receptor 2 (HER2) overexpression accounts for 30% of invasive breast cancer (BC) and is critically associated with aggressive disease, recurrence and metastasis. Adoptive cell therapy approaches using cytotoxic CD8 T cells and natural killer cells have been shown to trigger anti-tumor immunity in BC. However, the immunosuppressive tumor microenvironment (TME) can inhibit response to these therapies and diminish the presence and function of tumor-infiltrating lymphocytes. Recently, we have shown a critical role for anti-tumor CD4 Th1 cells in dendritic cells (DC) intratumoral (i.t.) delivery in combination with anti-HER2 therapy. This combination therapy enhanced systemic and local anti-tumor immunity and eradicated tumors in HER2 positive BC with a requirement for CD4 Th1 cells. Here we investigated the efficacy of i.t. delivery of both autologous anti-tumor CD4 Th1 cells and tumor antigen pulsed type 1 polarized dendritic cells (HER2-DC1) in a HER2 mammary carcinoma model. CD4 T cells were isolated from BALB/c mice that had completely regressed (pCR) from orthotopic TUBO tumors following HER2-DC1 i.t. or combination therapy with anti-HER2 antibody. CD4 Th1 cells were then expanded by co-culturing with HER2-DC1 in the presence of interleukin (IL)-2 and IL-7 cytokines. BALB/c mice bearing orthotopic TUBO tumors were treated weekly for six weeks with anti-tumor CD4 Th1 cells i.t., non-specific CD4 Th1 cells i.t., HER2-DC1 i.t. or combination therapy. The i.t. delivery of anti-tumor CD4 Th1 cells combined with HER2-DC1 induced a strong anti-tumor response with survival benefit and complete tumor eradication in 50% of treated mice. Importantly, the i.t. delivery of anti-tumor CD4 Th1 cells were critical for providing priming signals to HER2-DC1 within the TME via CD40/CD40L engagement (licensing). This was supported by a strong anti-tumor response and complete tumor regression in 60% of orthotopic TUBO tumor bearing mice treated with CD40/CD40L licensed HER2-DC1 i.t. therapy compared to un-licensed HER2-DC1 i.t. therapy. Additionally, enhanced survival and functionality of human and mouse HER2-DC1 was observed following activation of CD40/CD40L signaling using anti-CD40 agonistic antibody in vitro. Collectively, these results suggest a new promising therapeutic strategy using DC1-anti-tumor CD4 Th1 adoptive cell therapy intratumoral delivery to induce DC1 priming and create robust anti-tumor immunity within the TME in BC.

Citation Format: Ganesan Ramamoorthi, Amy Aldrich, Colin Snyder, Brian Czerniecki. Intratumoral delivery of autologous tumor antigen specific CD4 Th1 cells combined with dendritic cells eradicates HER2 mammary carcinoma. [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 4056.

Oncolytic T-VEC virotherapy plus neoadjuvant chemotherapy in nonmetastatic triple-negative breast cancer: a phase 2 trial

Talimogene laherparepvec (T-VEC) is an oncolytic virus hypothesized to enhance triple-negative breast cancer (TNBC) responses to neoadjuvant chemotherapy (NAC). This article describes the phase 2 trial of T-VEC plus NAC (ClinicalTrials.gov ID: NCT02779855 ). Patients with stage 2-3 TNBC received five intratumoral T-VEC injections with paclitaxel followed by doxorubicin and cyclophosphamide and surgery to assess residual cancer burden index (RCB). The primary end point was RCB0 rate. Secondary end points were RCB0-1 rate, recurrence rate, toxicity and immune correlates. Thirty-seven patients were evaluated. Common T-VEC toxicities were fevers, chills, headache, fatigue and injection site pain. NAC toxicities were as expected. Four thromboembolic events occurred. The primary end point was met with an estimated RCB0 rate = 45.9% and RCB0-1 descriptive rate = 65%. The 2-year disease-free rate is equal to 89% with no recurrences in RCB0-1 patients. Immune activation during treatment correlated with response. T-VEC plus NAC in TNBC may increase RCB0-1 rates. These results support continued investigation of T-VEC plus NAC for TNBC.

MEETING HIGHLIGHTS: THE THIRD MARIE SKŁODOWSKA-CURIE SYMPOSIUM ON CANCER RESEARCH AND CARE AT ROSWELL PARK COMPREHENSIVE CANCER CENTER, BUFFALO, NY, SEPTEMBER 20-22, 2023

Marie Skłodowska-Curie Symposia on Cancer Research and Care (MSCS-CRC) promote collaborations between cancer researchers and care providers in the United States, Canada and Central and Eastern European Countries (CEEC), to accelerate the development of new cancer therapies, advance early detection and prevention, increase cancer awareness, and improve cancer care and the quality of life of patients and their families. The third edition of MSCS-CRC, held at Roswell Park Comprehensive Cancer Center, Buffalo, NY, in September 2023, brought together 137 participants from 20 academic institutions in the US, Poland, Ukraine, Lithuania, Croatia and Hungary, together with 16 biotech and pharma entities. The key areas of collaborative opportunity identified during the meeting are a) creating of a database of available collaborative projects in the areas of early-phase clinical trials, preclinical development, and identification of early biomarkers; b) promoting awareness of cancer risks and efforts at cancer prevention; c) laboratory and clinical training; and d) sharing experience in cost-effective delivery of cancer care and improving the quality of life of cancer patients and their families. Examples of ongoing international collaborations in the above areas were discussed. Participation of the representatives of the Warsaw-based Medical Research Agency, National Cancer Institute (NCI) of the United States, National Cancer Research Institutes of Poland and Lithuania, New York State Empire State Development, Ministry of Health of Ukraine and Translational Research Cancer Center Consortium of 13 cancer centers from the US and Canada, facilitated the discussion of available governmental and non-governmental funding initiatives in the above areas.

Abstract B016: Guiding de-escalation of treatment for patients with DCIS using a predictive 7-gene biosignature: Identification of a clinically low-risk patient group

Background: NCCN treatment guidelines support de-escalation of radiotherapy (RT) for “low risk” patients with ductal carcinoma in situ (DCIS) treated with breast conserving surgery (BCS) for which improved specificity in identifying patients with low in-breast recurrence (IBR) rates who are unlikely to benefit from RT is needed. “low risk” has been defined as the absence of “high risk” clinicopathological (CP) factors, which include younger age (&lt;50 yrs) or tumors that are 2 cm or larger, palpable, or high nuclear grade. However, these CP factors have failed to identify a patient group with lower recurrence risk that do not clinically benefit from RT after BCS. Thus, the clinical utility of a Low Risk group identified by the predictive 7-gene biosignature was characterized overall and for patient subsets meeting “low risk” or “high risk” CP criteria. Methods: DCIS patients (n=926) from four international cohorts treated with BCS (negative margins) with (n=641) and without RT (n=335) were evaluated for CP criteria (age&lt;50 or grade 3, and RTOG 9804 like) and clinical outcomes. Formalin-fixed paraffin-embedded tissue samples for each patient were analyzed at a CLIA lab (PreludeDx, Laguna Hills, CA) for the predictive 7-gene biosignature with a Residual Risk subtype (RRt). The biosignature reported a decision score (DS) of 0-10 and presence/absence of the RRt subtype. A Low Risk group (DS≤2.8 without RRt) was compared with the combined Elevated Risk (DS&gt;2.8 without RRt) and Residual Risk groups (DS&gt;2.8 with RRt), where 10-yr total IBR rates were evaluated using Cox Proportional Hazards and Kaplan Meier analysis by treatment, biosignature Risk group, and CP criteria. Results: The biosignature classified 37% of women treated with BCS as Low Risk (n=338) and 63% (n=588) were classified into the combined Elevated/Residual Risk group. Among patients who did not receive RT, those in the Elevated/Residual Risk group had higher IBR rates (p&lt;.001) than those in the Low Risk group, with corresponding 10-yr IBR rates of 25.7% (95% CI: 18.8%, 34.4%) vs 5.6% (95% CI: 2.5%, 12.1%), respectively. RT did not reduce the IBR rate in the Low Risk group (p=0.71), where the 10-yr IBR rate was 4.8% (95% CI: 2.5%, 9.1%) after RT, corresponding to a number needed to treat (NNT) of ~100. However, the Elevated/Residual Risk group benefited from RT (p&lt;0.001), with a 17.7% (95% CI: 9.4%, 26%) absolute 10-year IBR rate reduction, corresponding to a NNT of 6. The biosignature reclassified 35-40% of patients with “high risk” CP criteria into the Low Risk group. IBR rates in the Low Risk group for patients with “high risk” CP were not significantly different than those with “low risk” CP criteria. Conclusion: The 7-gene biosignature was a better predictor of prognosis and RT benefit than standard CP risk stratification, identifying a low risk group with no significant benefit from RT. The 10-yr IBR rate with or without RT remained consistent in the biosignature Low Risk group independent of CP criteria, further supporting identification of a true low risk group who may forgo RT.

Citation Format: Rachel Rabinovitch, Frank A. Vicini, Chirag Shah, Julie Margenthaler, Brian Czerniecki, Pat Whitworth, Sheila Weinmann, Michael C. Leo, Fredrik Wärnberg, G. Bruce Mann, Steven C. Shivers, David Dabbs, Karuna Mittal, Troy Bremer. Guiding de-escalation of treatment for patients with DCIS using a predictive 7-gene biosignature: Identification of a clinically low-risk patient group [abstract]. In: Proceedings of the AACR Special Conference on Rethinking DCIS: An Opportunity for Prevention?; 2022 Sep 8-11; Philadelphia, PA. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_1): Abstract nr B016.

EXTH-01. INTRATHECAL DELIVERY OF DENDRITIC CELL VACCINE ERADICATES TUMOR GROWTH AND PROTECTS AGAINST LEPTOMENINGEAL DISEASE RE-INOCULATION IN HER2+ AND TRIPLE NEGATIVE BREAST CANCER LMD XENOGRAFT MODELS

BACKGROUND

Leptomeningeal disease (LMD) occurs in approximately 5% of patients with breast cancer and has a median survival of 2-4 months. We found a loss of the anti-HER2 and anti-HER3 CD4 Th1 immune responses in breast cancer patients. In pre-clinical and clinical trials, the administration of class II HER2 peptide-pulsed dendritic cell vaccine (HER2-DCV) partially restores anti-HER2 Th1 immune responses with pathologic complete responses in HER2+ breast cancer patients. Here, we examined the intrathecal (IT) delivery of HER2/HER3-DCV in breast cancer-associated LMD immunocompetent animal models.

METHODS

Luciferase-labeled HER2+ TUBO breast cancer cells were injected into the cisterna magna of BALB/c mice to produce LMD. We used our Murine Ommaya (mimics an Ommaya reservoir in patients) for the IT administration of DCVs into the CSF. RESULTS AND

DISCUSSION

breast cancer-LMD mice were randomized into following groups: 1) HER2-DCV IT 2) HER3-DCV IT 3) HER2/HER3-DCV IT. The median survival of untreated (control) group was 15 days. All groups given DCV IT prolonged survival (p&lt; 0.001). Interestingly, HER2-/HER3-DCV IT was able to rescue disease mice (71% in HER2+ breast cancer-LMD and 28% in triple negative breast cancer-LMD) and showed complete tumor regression. Some surviving mice were immune to subsequent tumor rechallenge. In mice CSF, we found evidence of CD4+ and CD8+ T-cells infiltration, and robust IFN-g and IL18 response upon DCV treatment.

CONCLUSIONS

Our preclinical data supported a clinical trial (submitted) of the IT delivery of DCV in breast cancer patients with LMD.

Ablation of the endoplasmic reticulum stress kinase PERK induces paraptosis and type I interferon to promote anti-tumor T cell responses

Activation of unfolded protein responses (UPRs) in cancer cells undergoing endoplasmic reticulum (ER) stress promotes survival. However, how UPR in tumor cells impacts anti-tumor immune responses remains poorly described. Here, we investigate the role of the UPR mediator pancreatic ER kinase (PKR)-like ER kinase (PERK) in cancer cells in the modulation of anti-tumor immunity. Deletion of PERK in cancer cells or pharmacological inhibition of PERK in melanoma-bearing mice incites robust activation of anti-tumor T cell immunity and attenuates tumor growth. PERK elimination in ER-stressed malignant cells triggers SEC61β-induced paraptosis, thereby promoting immunogenic cell death (ICD) and systemic anti-tumor responses. ICD induction in PERK-ablated tumors stimulates type I interferon production in dendritic cells (DCs), which primes CCR2-dependent tumor trafficking of common-monocytic precursors and their intra-tumor commitment into monocytic-lineage inflammatory Ly6C+CD103+ DCs. These findings identify how tumor cell-derived PERK promotes immune evasion and highlight the potential of PERK-targeting therapies in cancer immunotherapy.

OS11.4.A Intrathecal delivery of dendritic cell vaccine eradicates tumor growth and protects against leptomeningeal disease re-inoculation in immunocompetent HER2+ and triple negative breast cancer leptomeningeal disease xenograft models

Background

Leptomeningeal disease (LMD) occurs in ~5% of patients with breast cancer (BC) and has a median survival of 2-4 months. We found a loss of the anti-HER2 and anti-HER3 CD4 Th1 immune responses in BC patients. In pre-clinical and clinical trials the administration of class II HER2 peptide-pulsed dendritic cell vaccine (HER2-DCV) partially restores anti-HER2 Th1 immune responses with pathologic complete responses in HER2+ BC patients. Here, we examined the intrathecal (IT) delivery of HER2/HER3-DCV in BC-LMD immunocompetent animal models.

Material and Methods

Luciferase-labeled HER2+ TUBO BCs were injected into the cisterna magna of BALB/c mice to produce LMD. We used our Murine Ommaya (mimics an Ommaya reservoir clinically in patients) for the IT administration of DCVs into the cerebral spinal fluid (CSF).

Results

BC-LMD mice were randomized into following groups: 1) HER2-DCV IT 2) HER3-DCV IT 3) HER2/HER3-DCV IT. The median survival of untreated (control) group was 15 days. All groups given DCV IT prolonged survival (p&lt;0.001). Interestingly, HER2-/HER3-DCV IT was able to rescue disease mice (71% in HER2+ BC-LMD and 28% in triple negative breast cancer-LMD) and showed complete tumor regression. Some surviving mice were immune to subsequent tumor rechallenge. In mice CSF, we found evidence of CD4+ and CD8+ T-cells infiltration, and robust IFN-gamma and IL18 response upon DCV treatment.

Conclusion

Our preclinical data supported a clinical trial (submitted) of the IT delivery of DCV in BC patients with LMD.

BSCI-01 INTRATHECAL DELIVERY OF DENDRITIC CELL VACCINE ERADICATES TUMOR GROWTH AND PROTECTS AGAINST LEPTOMENINGEAL DISEASE (LMD) RE-INOCULATION IN IMMUNOCOMPETENT HER2+ AND TRIPLE NEGATIVE BREAST CANCER (TNBC) LMD XENOGRAFT MODELS

BACKGROUND

LMD occurs in ~5% of patients with breast cancer (BC) and has a median survival of 2-4 months. We found a loss of the anti-HER2 and anti-HER3 CD4 Th1 immune responses in BC patients. In pre-clinical and clinical trials the administration of class II HER2 peptide-pulsed dendritic cell vaccine (HER2-DCV) partially restores anti-HER2 Th1 immune responses with pathologic complete responses in HER2+ BC patients. Here, we examined the intrathecal (IT) delivery of HER2/HER3-DCV in BC-LMD immunocompetent animal models.

MATERIALS AND METHODS

Luciferase-labeled HER2+ TUBO BCs were injected into the cisterna magna of BALB/c mice to produce LMD. We used our Murine Ommaya (mimics an Ommaya reservoir clinically in patients) for the IT administration of DCVs into the cerebral spinal fluid (CSF).

RESULTS AND DISCUSSION

BC-LMD mice were randomized into following groups: 1) HER2-DCV IT 2) HER3-DCV IT 3) HER2/HER3-DCV IT. The median survival of untreated (control) group was 15 days. All groups given DCV IT prolonged survival (p&lt;0.001). Interestingly, HER2-/HER3-DCV IT was able to rescue disease mice (71% in HER2+ BC-LMD and 28% in TNBC-LMD) and showed complete tumor regression. Some surviving mice were immune to subsequent tumor rechallenge. In mice CSF, we found the presence of CD4+ and CD8+ T-cells, and robust IFN-gamma and IL18 response upon DCV treatment. Collectively, this suggests IT delivery of DCV elicits immune response in CSF targeting LMD.

CONCLUSION

Our preclinical data supported a clinical trial (submitted) of the IT delivery of DCV in BC patients with LMD.

Quantitative Changes in Intratumoral Habitats on MRI Correlate With Pathologic Response in Early-stage ER/PR+ HER2- Breast Cancer Treated With Preoperative Stereotactic Ablative Body Radiotherapy

Objective

To quantitatively evaluate intratumoral habitats on dynamic contrast-enhanced (DCE) breast MRI to predict pathologic breast cancer response to stereotactic ablative body radiotherapy (SABR).

Methods

Participants underwent SABR treatment (28.5 Gy x3), baseline and post-SABR MRI, and breast-conserving surgery for ER/PR+ HER2- breast cancer. MRI analysis was performed on DCE T1-weighted images. MRI voxels were assigned eight habitats based on high (H) or low (L) maximum enhancement and the sequentially numbered dynamic sequence of maximum enhancement (H1-4, L1-4). MRI response was analyzed by percent tumor volume remaining (%VR = volume post-SABR/volume pre-SABR), and percent habitat makeup (%HM of habitat X = habitat X voxels/total voxels in the segmented volume). These were correlated with percent tumor bed cellularity (%TC) for pathologic response.

Results

Sixteen patients completed the trial. The %TC ranged 20%-80%. MRI %VR demonstrated strong correlations with %TC (Pearson R = 0.7-0.89). Pre-SABR tumor %HMs differed significantly from whole breasts (P = 0.005 to <0.00001). Post-SABR %HM of tumor habitat H4 demonstrated the largest change, increasing 13% (P = 0.039). Conversely, combined %HM for H1-3 decreased 17% (P = 0.006). This change correlated with %TC (P < 0.00001) and distinguished pathologic partial responders (≤70 %TC) from nonresponders with 94% accuracy, 93% sensitivity, 100% specificity, 100% positive predictive value, and 67% negative predictive value.

Conclusion

In patients undergoing preoperative SABR treatment for ER/PR+ HER2- breast cancer, quantitative MRI habitat analysis of %VR and %HM change correlates with pathologic response.

A preclinical model of patient-derived cerebrospinal fluid circulating tumor cells for experimental therapeutics in leptomeningeal disease from melanoma

BACKGROUND

Leptomeningeal disease (LMD) occurs as a late complication of several human cancers and has no rationally designed treatment options. A major barrier to developing effective therapies for LMD is the lack of cell-based or preclinical models that recapitulate human disease. Here, we describe the development of in vitro and in vivo cultures of patient-derived cerebrospinal fluid circulating tumor cells (PD-CSF-CTCs) from patients with melanoma as a preclinical model to identify exploitable vulnerabilities in melanoma LMD.

METHODS

CSF-CTCs were collected from melanoma patients with melanoma-derived LMD and cultured ex vivo using human meningeal cell-conditioned media. Using immunoassays and RNA-sequencing analyses of PD-CSF-CTCs, molecular signaling pathways were examined and new therapeutic targets were tested for efficacy in PD-CSF-CTCs preclinical models.

RESULTS

PD-CSF-CTCs were successfully established both in vitro and in vivo. Global RNA analyses of PD-CSF-CTCs revealed several therapeutically tractable targets. These studies complimented our prior proteomic studies highlighting IGF1 signaling as a potential target in LMD. As a proof of concept, combining treatment of ceritinib and trametinib in vitro and in vivo demonstrated synergistic antitumor activity in PD-CSF-CTCs and BRAF inhibitor-resistant melanoma cells.

CONCLUSIONS

This study demonstrates that CSF-CTCs can be grown in vitro and in vivo from some melanoma patients with LMD and used as preclinical models. These models retained melanoma expression patterns and had signaling pathways that are therapeutically targetable. These novel models/reagents may be useful in developing rationally designed treatments for LMD.

Abstract OT1-16-01: A multicenter phase II study of vaccines to prevent recurrence in patients with HER-2 positive breast cancer

Background: HER2-positive breast cancer patients are commonly treated with neoadjuvant therapy including HER2-targeted therapy. Patients who have residual invasive disease have less favorable outcomes with an increased risk of recurrent disease than patients with complete pathologic response (pCR). It has also been observed that these non-pCR patients have low or absent anti-HER-2 CD4 Th1 responses. We hypothesized that correcting the anti-HER-2 CD4 Th1 response using vaccines will increase interferon gamma production which we have shown is a potent inducer of apoptosis and senescence in HER2-positive breast cancer. This study will be evaluating safety and immunogenicity of two vaccines (multivalent anti-oncodriver DNA vaccine (WOKVAC) or HER-2-pulsed dendritic cell vaccine (DC1)). Methods: This is a multi-center, phase 2, randomized study to determine the safety and tolerability of HER2 vaccines (DC1 and WOKVAC), assess immunogenicity, and evaluate recurrence free survival. Patients with HER2-positive early breast cancer (stage I-III) are eligible if they have residual invasive disease in the breast or axilla at surgery after receiving neoadjuvant chemotherapy plus HER2 -targeted therapy. Patients are randomly assigned in a 1:1 ratio to receive 1 of 2 adjuvant HER2 vaccines, either DC1 or WOKVAC for 1 year. A permuted-block randomization scheme was used with stratification according to residual cancer burden (RCB) (1+2 vs 3). The primary end points are safety and immunogenicity (immune response rate measured by ELISPOT). Each treatment arm will be assessed separately. Any statistical comparison between arms is purely exploratory, as this study is neither designed nor powered for comparative hypotheses. Secondary endpoints include recurrence-free survival. Exploratory analyses include the assessment of prognostic and predictive biomarkers including circulating tumor cells, serum HER2 levels, and other immune markers. The enrollment began in 2018 and we plan to accrue the total of 110 patients. ClinicalTrials.gov Identifier: NCT03384914

Citation Format: Hyo S Han, Mary Disis, Robert Wesolowski, Carla Fisher, Shipra Gandhi, Nancy Chan, William Gwin, Keerthi Gogineni, Rosemarie Mick, Christina Sierra Rodriguez, Deanna Hogue, Hien Liu, Ricardo Costa, Brian Czerniecki. A multicenter phase II study of vaccines to prevent recurrence in patients with HER-2 positive breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT1-16-01.

Abstract P2-14-01: Phase II neoadjuvant trial of Interferon-gamma plus weekly paclitaxel, trastuzumab and pertuzumab in patients with HER-2 positive breast cancer

Background: IFN-γ, a cytokine that plays diverse roles in innate and adaptive immunity, has been shown to be essential in anti-tumor immune response. In vitro and in vivo studies have shown the synergistic effect of IFN-γ in combination with HER2-targeting monoclonal antibodies with or without taxane chemotherapy. We previously conducted a phase I trial of IFN-γ in combination with paclitaxel, trastuzumab and pertuzumab (IPTP) in metastatic HER2-positive breast cancer (HER2+ BC) based on which we initiated a phase II neoadjuvant study with this combination. Methods: Early stage HER2+ BC patients (pts) were eligible. Treatment included 12 weeks of weekly paclitaxel 80 mg/m2 IV, trastuzumab IV every 3 weeks x 4 (8 mg/kg loading dose, then 6 mg/kg) and pertuzumab IV every 3 weeks x 4 (840 mg loading dose, then 420 mg) in combination with IFN-γ 50 mcg/m2 subcutaneous injection three times weekly starting on day 1. The primary objective was to evaluate the pathologic complete response rate (pCR) in breast and nodes. This study had a planned interim analysis after 23 patients were evaluable for pCR based on a Simon’s two stage design with 90% power and a type I error rate of 0.1. The final proportion of hormone receptor (HR) status among accrued patients will be used for comparison to historical control because pCR is expected to be lower for HR+HER2+BC compared to HR-HER2+ BC subtype (25% vs 50% respectively). Here we are reporting the final results. Results: Thirty-nine pts were enrolled between 1/2018 and 11/2020. Most patients had clinical stage II/III (90%) and 46% were clinically and pathologically node positive. Thirty four out of 39 (87%) had HR+ BC. The pCR for all patients was 44% (17/39). The pCR for HR+ HER2+ and HR-HER2+ BC subgroup was 47% (16/34) and 20% (1/5) respectively. Further evaluation using RCB (residual cancer burden) showed 17 pts RCB-0, 6 RCB-I,14 RCB-II, and 2 RCB-III. Two SAE included pneumonitis/heart failure and hematochezia. The most frequently observed grade 1 and 2 AEs were diarrhea (74%), fatigue (74%), rash (56%) and nausea (56%). Grade 3 AE (5% or higher) included diarrhea (18%), syncope (5%) and rash (5%). No grade 4 AE was noted. Conclusion: The addition of IFN-γ to neoadjuvant chemotherapy using paclitaxel, trastuzumab and pertuzumab was well tolerated with manageable toxicities. This study evaluated de-escalated treatments only 12 weeks duration and the anthracycline-free regimen which was highly effective with pCR of 44%. The pCR for HR+ HER2 + BC subtype was 47% (16/34) which compares favorably to the expected pCR of 25% with neoadjuvant chemotherapy alone in HR+HER2+ patients. Updated results will be presented at the meeting including correlative studies.

Citation Format: Hyo S Han, Ricardo Costa, Avan Armaghani, Aixa Soyano, Loretta Loftus, Hatem Soliman, Brooke Fridley, Junmin Whiting, Aiana Cerezo, Marilin Rosa, Martine Extermann, Hung Khong, Brian Czerniecki. Phase II neoadjuvant trial of Interferon-gamma plus weekly paclitaxel, trastuzumab and pertuzumab in patients with HER-2 positive breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-14-01.

MRI Response to Pre-operative Stereotactic Ablative Body Radiotherapy (SABR) in Early Stage ER/PR+ HER2- Breast Cancer correlates with Surgical Pathology Tumor Bed Cellularity

OBJECTIVE

This study evaluates breast MRI response of ER/PR+ HER2- breast tumors to pre-operative SABR with pathologic response correlation.

METHODS

Women enrolled in a phase 2 single institution trial of SABR for ER/PR+ HER2- breast cancer were retrospectively evaluated for radiologic-pathologic correlation of tumor response. These patients underwent baseline breast MRI, SABR (28.5 Gy in 3 fractions), follow-up MRI 5 to 6 weeks post-SABR, and lumpectomy. Tumor size and BI-RADS descriptors on pre and post-SABR breast MRIs were compared to determine correlation with surgical specimen % tumor cellularity (%TC). Reported MRI tumor dimensions were used to calculate percent cubic volume remaining (%VR). Partial MRI response was defined as a BI-RADs descriptor change or %VR ≤ 70%, while partial pathologic response (pPR) was defined as %TC ≤ 70%.

RESULTS

Nineteen patients completed the trial, and %TC ranged 10% to 80%. For BI-RADS descriptor analysis, 12 of 19 (63%) showed change in lesion or kinetic enhancement descriptors post-SABR. This was associated with lower %TC (29% vs. 47%, P = .042). BI-RADS descriptor change analysis also demonstrated high PPV (100%) and specificity (100%) for predicting pPR to treatment (sensitivity 71%, accuracy 74%), but low NPV (29%). MRI %VR demonstrated strong linear correlation with %TC (R = 0.70, P < .001, Pearson's Correlation) and high accuracy (89%) for predicting pPR (sensitivity 88%, specificity 100%, PPV 100%, and NPV 50%).

CONCLUSION

Evaluating breast cancer response on MRI using %VR after pre-operative SABR treatment can help identify patients benefiting the most from neoadjuvant radiation treatment of their ER/PR+ HER2- tumors, a group in which pCR to neoadjuvant therapy is rare.

Surgical Predictive Model for Breast Cancer Patients Assessing Acute Postoperative Complications: The Breast Cancer Surgery Risk Calculator

BACKGROUND

Prognostic tools, such as risk calculators, improve the patient-physician informed decision-making process. These tools are limited for breast cancer patients when assessing surgical complication risk preoperatively.

OBJECTIVE

In this study, we aimed to assess predictors associated with acute postoperative complications for breast cancer patients and then develop a predictive model that calculates a complication probability using patient risk factors.

METHODS

We performed a retrospective cohort study using the National Surgical Quality Improvement Program (NSQIP) database from 2005 to 2017. Women diagnosed with ductal carcinoma in situ or invasive breast cancer who underwent either breast conservation or mastectomy procedures were included in this predictive modeling scheme. Four models were built using logistic regression methods to predict the following composite outcomes: overall, infectious, hematologic, and internal organ complications. Model performance, accuracy and calibration measures during internal/external validation included area under the curve, Brier score, and Hosmer-Lemeshow statistic, respectively.

RESULTS

A total of 163,613 women met the inclusion criteria. The area under the curve for each model was as follows: overall, 0.70; infectious, 0.67; hematologic, 0.84; and internal organ, 0.74. Brier scores were all between 0.04 and 0.003. Model calibration using the Hosmer-Lemeshow statistic found all p-values to be > 0.05. Using model coefficients, individualized risk can be calculated on the web-based Breast Cancer Surgery Risk Calculator (BCSRc) platform ( www.breastcalc.org ).

CONCLUSION

We developed an internally and externally validated risk calculator that estimates a breast cancer patient's unique risk of acute complications following each surgical intervention. Preoperative use of the BCSRc can potentially help stratify patients with an increased complication risk and improve expectations during the decision-making process.

A Murine Ommaya Xenograft Model to Study Direct-Targeted Therapy of Leptomeningeal Disease

Leptomeningeal disease (LMD) is an uncommon type of central nervous system (CNS) metastasis to the cerebral spinal fluid (CSF). The most common cancers that cause LMD are breast and lung cancers and melanoma. Patients diagnosed with LMD have a very poor prognosis and generally survive for only a few weeks or months. One possible reason for the lack of efficacy of systemic therapy against LMD is the failure to achieve therapeutically effective concentrations of drug in the CSF because of an intact and relatively impermeable blood-brain barrier (BBB) or blood-CSF barrier across the choroid plexus. Therefore, directly administering drugs intrathecally or intraventricularly may overcome these barriers. This group has developed a model that allows for the effective delivery of therapeutics (i.e., drugs, antibodies, and cellular therapies) chronically and the repeated sampling of CSF to determine drug concentrations and target modulation in the CSF (when the tumor microenvironment is targeted in mice). The model is the murine equivalent of a magnetic resonance imaging-compatible Ommaya reservoir, which is used clinically. This model, which is affixed to the skull, has been designated as the "Murine Ommaya." As a therapeutic proof of concept, human epidermal growth factor receptor 2 antibodies (clone 7.16.4) were delivered into the CSF via the Murine Ommaya to treat mice with LMD from human epidermal growth factor receptor 2-positive breast cancer. The Murine Ommaya increases the efficiency of drug delivery using a miniature access port and prevents the wastage of excess drug; it does not interfere with CSF sampling for molecular and immunological studies. The Murine Ommaya is useful for testing novel therapeutics in experimental models of LMD.

Strategies to Combat Human Epidermal Growth Factor Receptor 2 (HER2) Resistance in HER2-Positive Breast Cancer

The discovery of human epidermal growth factor receptor 2 (HER2) and its role in breast cancer led to the development of the first targeted antibody treatment for HER2-positive breast cancer. This treatment breakthrough led to remarkable improvements in both early and late survival. Unfortunately, not all patients with HER2 breast cancer responded positively; some have innate resistance to treatment and others develop resistance over time. In this review, we discuss some research that is currently underway to understand HER2 resistance and strategies in overcoming it.

A Phase I Trial of Talimogene Laherparepvec in Combination with Neoadjuvant Chemotherapy for the Treatment of Nonmetastatic Triple-Negative Breast Cancer

PURPOSE

Talimogene laherparepvec (TVEC) is an oncolytic herpes simplex 1 virus approved for treatment of melanoma. We hypothesized intratumoral TVEC may enhance response to neoadjuvant chemotherapy (NAC). This article reports the results of a trial combining NAC with TVEC for triple-negative breast cancer (TNBC).

PATIENTS AND METHODS

Patients with stage II-III TNBC enrolled in a 3+3 phase I trial (NCT02779855) of two TVEC dose levels [DL; DL 1 = 10⁶ plaque-forming units (PFU) × 5 doses; DL 2 = 10⁶ PFUs first dose, then 10⁸ PFUs × 4 doses] on weeks 1, 4, 6, 8, and 10 plus weekly paclitaxel (80 mg/m²) for 12 weeks, followed by doxorubicin/cyclophosphamide (60/600 mg/m²) every 2 weeks for 8 weeks. Postoperative response assessment using residual cancer burden (RCB) was performed. Primary endpoints were safety and MTD. Secondary endpoints were RCB0 rate and immune correlates. Dose-limiting toxicity (DLT) rule was grade 3-5 adverse events due to TVEC during first 5 weeks.

RESULTS

Nine patients [DL 1 (n = 3); DL 2 (n = 6)] were enrolled. Six had stage II disease, and 3 had stage III (6 clinically N⁺). No DLTs occurred, and MTD was DL 2. Most common toxicities with TVEC were fever (n = 8), chills (n = 3), hematomas (n = 3), and injection site pain (n = 3). Thromboembolic events (n = 2) and bradycardia (n = 1) occurred during or after NAC. Five patients (55%) achieved RCB0, 2 had RCB1 (22%), and 2 had RCB2 (22%).

CONCLUSIONS

The addition of TVEC to NAC was feasible at the approved dose, with manageable toxicity. The complete response rate was 55%.

EXTH-04. INTRATHECAL (IT) DELIVERY OF TYPE I POLARIZED DENDRITIC CELL VACCINE (DC1) ERADICATES TUMOR GROWTH IN BREAST CANCER (BC) XENOGRAFT MODEL WITH BRAIN METASTASES (BM) AND LEPTOMENINGEAL DISEASE (LMD)

BACKGROUND

Approx. 5% of BM will also develop LMD. Currently there is no effective treatment for BC-associated BM/LMD. As systemic therapies do not prevent the disease recurrence and eventual death, the better option would be direct-targeted approach. We have shown that there is a loss of the anti-HER2 and anti-HER3 CD4 Th1 immune response in BC patients (pts). In a clinical setting, administration of class II HER2 peptide-pulsed Type I polarized dendritic cell vaccine (HER2-DC1) partially restored anti-HER2 Th1 immune responses with pathologic complete response in HER2+ BC patients. In this study, we examined the IT delivery of HER2/HER3- DC1 in BC-LMD model.

METHODS

Luciferase-labeled HER2+ TUBO BC cell line was injected into the cisterna magna of BALB/c mice to develop BM/LMD. We developed a technique, coined the “Top Hat” (TH) for mouse model that mimics the Ommaya reservoir in BC-pts. The TH essentially allows us to administer IT treatment directly into CSF. BC-BM/LMD bearing mice were given HER2- and Her3 peptide-pulsed Type I polarized DC1 through the TH.

RESULTS AND DISCUSSION

BM/LMD mice were randomized into following groups: 1) systemic Her2-DC1 2) IT Her2-DC1 3) IT Her2-/Her3-DC1. The median survival (MS) of control mice was 10 days and systemically treated mice was 19 days. IT Her2-DC1 animals did significantly better than both control and systemic treated groups (MS: 63 days; p&lt; 0.0001) and overall survival (OS): 44%. Interestingly, mice given IT Her2-/Her3-DC1 had the best OS (78%). Surviving animals were eventually disease free. Mice that had complete tumor regression were immune to subsequent rechallenge with TUBO cells. Immune cell infiltration in the of CSF, spinal cord and tissues of experimental mice are currently ongoing.

CONCLUSIONS

Our preclinical data supports the clinical relevance of using intrathecal delivery of DC1 vaccine as a potential treatment for BM and LMD of BC-pts.

Abstract CT185: A phase II neoadjuvant trial of Interferon-gamma plus weekly paclitaxel, trastuzumab and pertuzumab in patients with HER-2 positive breast cancer

Background: IFN-γ, a cytokine that plays diverse roles in innate and adaptive immunity, has been shown to be essential in anti-tumor immune response. In vitro and in vivo studies have shown the synergistic effect of IFN-γ in combination with HER2-targeting monoclonal antibodies with or without taxane chemotherapy. We previously conducted a phase I trial of IFN-γ in combination with paclitaxel, trastuzumab and pertuzumab (IPTP) in metastatic HER2-positive breast cancer (HER2+BC) based on which we initiated a phase II neoadjuvant study with this combination. Methods: Early stage HER2+BC patients were eligible. Treatment included 12 weeks of weekly paclitaxel 80 mg/m2 IV, trastuzumab IV every 3 weeks x 4 (8 mg/kg loading dose, then 6 mg/m2) and pertuzumab IV every 3 weeks x 4 (840 mg loading dose, then 420 mg) in combination with IFN-γ 50 mcg/m2 subcutaneous injection three times weekly starting on day 1. The primary objective was to evaluate the pathologic complete response rate (pCR) in breast and nodes. This study had a planned interim analysis after 23 patients were evaluable for pCR based on a Simon's two stage design with 90% power and a type I error rate of 0.1. The final proportion of hormone receptor (HR) status among accrued patients will be used for comparison to historical control because pCR is expected to be lower for HR+HER2+BC compared to HR-HER2+BC subtype (25% vs 50% respectively). Here we are reporting the planned interim analysis results. Results: Twenty three patients were enrolled between 1/2018 and 7/2019. Most patients had clinical stage II/III (86%) and 43% were clinically and pathologically node positive. Nineteen out of 23 (82%) had HR+ and 3 had invasive lobular carcinoma. The pCR for all patients was 52% (12/23). The pCR for HR+HER2+ and HR-HER2+ BC subgroup was 57% (11/19) and 25% (1/4) respectively. Further evaluation using RCB (residual cancer burden) showed 12 pts RCB-0, 5 RCB-I, 5 RCB-II, and 1 RCB-III. Two SAE included pneumonitis/heart failure and hematochezia. The most frequently observed grade 1 and 2 AEs were fatigue (69%), diarrhea (59%), rash (41%) and nausea (41%). Grade 3 toxicities (4% or higher) included diarrhea (n=3) and no grade 4 AE was noted.

Conclusion: The addition of IFN-γ to neoadjuvant chemotherapy using paclitaxel, trastuzumab and pertuzumab was well tolerated with manageable toxicities. This study evaluated de-escalated treatments only 12 weeks duration and the anthracycline-free regimen which was highly effective with pCR of 52%. The pCR for HR+HER2+BC subtype was 57% which compares favorably to the expected pCR of 25% with neoadjuvant chemotherapy alone in HR+HER2+ patients. This regimen met the criteria to proceed to the second stage of the phase II trial and appears promising especially in HR+HER2+BC. Updated results will be presented at the meeting including correlative studies.

Citation Format: Hyo S. Han, Dawn Goodridge, Avan Armaghani, Ricardo Costa, Aixa Soyano Muller, Loretta Loftus, Hatem Soliman, Brooke Fridley, Laila Khazai, Aiana Cerezo, Jesse Hevia, Marilin Rosa, Hung Khong, Brian Czerniecki. A phase II neoadjuvant trial of Interferon-gamma plus weekly paclitaxel, trastuzumab and pertuzumab in patients with HER-2 positive breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT185.

Immunologic Consequences of Sequencing Cancer Radiotherapy and Surgery

PURPOSE

Early-stage cancers are routinely treated with surgery followed by radiotherapy (SR). Radiotherapy before surgery (RS) has been widely ignored for some cancers. We evaluate overall survival (OS) and disease-free survival (DFS) with SR and RS for different cancer types and simulate the plausibility of RS- and SR-induced antitumor immunity contributing to outcomes.

MATERIALS AND METHODS

We analyzed a SEER data set of early-stage cancers treated with SR or RS. OS and DFS were calculated for cancers with sufficient numbers for statistical power (cancers of lung and bronchus, esophagus, rectum, cervix uteri, corpus uteri, and breast). We simulated the immunologic consequences of SR, RS, and radiotherapy alone in a mathematical model of tumor-immune interactions.

RESULTS

RS improved OS for cancers with low 20-year survival rates (lung: hazard ratio [HR], 0.88; P = .046) and improved DFS for cancers with higher survival (breast: HR = 0.64; P < .001). For rectal cancer, with intermediate 20-year survival, RS improved both OS (HR = 0.89; P = .006) and DFS (HR = 0.86; P = .04). Model simulations suggested that RS could increase OS by eliminating cancer for a broader range of model parameters and radiotherapy-induced antitumor immunity compared with SR for selected parameter combinations. This could create an immune memory that may explain increased DFS after RS for certain cancers.

CONCLUSION

Study results suggest plausibility that radiation to the bulk of the tumor could induce a more robust immune response and better harness the synergy of radiotherapy and antitumor immunity than postsurgical radiation to the tumor bed. This exploratory study provides motivation for prospective evaluation of immune activation of RS versus SR in controlled clinical studies.

Abstract OT1-01-06: A pilot study utilizing a HER2 directed dendritic cell vaccine during neoadjuvant therapy of HER2+ breast cancer

Background: During the natural progression of early breast cancer, it has been demonstrated that the protective host immune response against HER2 is lost early on. Using a type 1 dendritic cell (DC1) vaccine loaded with HER2 peptides has been shown to be effective in restoring anti HER2 immune responsiveness and can lead to regression of very early non-invasive breast cancers. Prior investigations conducted by our group has suggested DC vaccines may sensitize cancers to subsequent systemic chemotherapy, and the Geparnuevo trial also suggested a prechemotherapy dosing with checkpoint therapy may improve pathologic complete response (pCR) rates in TNBC. We launched a pilot study to demonstrate safety, feasibility, and preliminary efficacy of administering the DC1 HER2 vaccine for 3 weeks prior to the initiation of neoadjuvant systemic therapy for stage II-III ER-HER2+ breast cancer. Methods: This single site study is a pilot design with a safety run in phase (n = 12) followed by an expansion cohort of 18 patients. Patients with stage II-III ER-HER2+ breast cancer who are eligible to receive neoadjuvant HER2 based chemotherapy (TCHP) can enroll. The safety run in evaluates two schedules of DC1 vaccination (ARM A = once weekly x 3 weeks and ARM B = twice weekly x 3 weeks) and will enroll six patients in each arm. After the first 3 weeks of DC1 neoadjuvant chemotherapy will be administered using standard docetaxel, carboplatin, trastuzumab, and pertuzumab given intravenously once every 3 weeks for 6 cycles. Booster vaccines will be given at weeks 25, 56, 80, and 104 and immune monitoring will be performed at these timepoints. The safety run in will evaluate safety using CTCAE 4.03 criteria along with the immunogenicity of each arm measured by ELISPOT. The arm with the best immune response at 3 weeks will be selected to proceed forward during the expansion cohort using an endpoint of pCR. Secondary endpoints will be recurrence free survival rate at 3 years and immune response. The pilot design is hypothesis generating but is likely able to detect a significant difference in pCR if the true rate is 75% assuming a historical rate of 55%. Accrual to the safety run in phase is complete and the expansion phase is underway using the twice weekly vaccination schedule.

Citation Format: Hatem Soliman, Deanna Hogue, Hyo Han, Hung Khong, Ricardo Costa, Avan Armaghani, Axia Soyano Muller, Nazanin Khakpour, Marie C Lee, John Kiluk, Brian Czerniecki. A pilot study utilizing a HER2 directed dendritic cell vaccine during neoadjuvant therapy of HER2+ breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT1-01-06.

Abstract P2-17-03: Real-world benefit of CDK4/6 inhibitor and endocrine therapy combination in metastatic breast cancer and correlation with neutropenia

Background: Combination of a CDK4/6 inhibitor plus endocrine therapy has been shown to significantly improve the progression free survival (PFS) in patients with hormone-receptor (HR)+, HER2- metastatic breast cancer. The aims of this retrospective study was: 1) to evaluate the real-world benefit of palbociclib plus endocrine therapy as the first line treatment in HR+, HER2- metastatic breast cancer (mBC) and 2) to correlate efficacy of the combination with neutropenia (which is a common toxicity of CDK4/6 inhibitors). Methods: This study included HR+, HER2- advanced mBC patients who were treated with palbociclib plus an endocrine therapy (mainly letrozole) at Moffitt Cancer Center between January 1, 2015 and March 1, 2018. The PFS was determined using Kaplan-Meier analysis. The predictive value of absolute neutrophil count (ANC) and neutrophil-to-lymphocyte ratio (NLR) for PFS were investigated using the univariable and multivariable Cox models. Results: A total of 165 patients were included in this retrospective cohort study. The median PFS of the full cohort was 24.19 months (95% CI 18.93 to not reached). For patients with bone metastasis only (n = 54), the median PFS was not reached (95% CI 18.21 to not reached). For patients with non-bone-only metastasis (n = 111), the median PFS was 24.19 months (95% CI 16.33 to 33.82). Patients with higher absolute neutrophil counts (ANC) are at high risk of disease progression (HR 1.15; 95% CI 1.03 to 1.29, p = 0.013). We did not find a significant association between the value of NLR and the risk of disease progression (HR 1.07 95% 0.97 to 1.18, p = 0.203). Both ANC and NLR were used as a time dependent variable. Conclusion:The effectiveness of palbociclib plus letrozole in the treatment of HR+, HER2- metastatic breast cancer in the real-world setting was found to be similar to the results from the PALOMA-2 trial. In addition, patients with a higher ANC were found to have a higher risk for early disease progression. This has implication for clinical practice [i.e., frequent dose delay and/or dose reduction based on ANC threshold of 1000/uL may not be an optimal approach. Since infection is rare, it is reasonable to reduce this threshold to a lower level such as 750-800/uL].

Citation Format: Dakota Jenneman, Xiaojun Zhong, Junjie Ma, Weihong Sun, Heather Han, Hatem Soliman, Loretta Loftus, Ricardo Costa, Avan Armaghani, Aixa Soyano, Brian Czerniecki, M. Catherine Lee, John Kiluk, Nazanin Khakpour, Susan Hoover, Christine Laronga, Hung T Khong. Real-world benefit of CDK4/6 inhibitor and endocrine therapy combination in metastatic breast cancer and correlation with neutropenia [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-17-03.

Abstract 1451: HER2 peptide pulsed dendritic cell vaccine induce senescence and eliminates disseminated cancer cells in a preventive model of transgenic HER2/neu breast cancer

HER-2/neu overexpression plays a critical role in breast cancer development, and its expression in ductal carcinoma in situ (DCIS) is associated with development of invasive breast cancer. The detection of disseminated cancer cells (DCCs) in early-stage DCIS likely to become invasive and manifests prominent role in metastasis and recurrence. The HER2-positive DCCs can easily escape targeted therapies and become a source of tumor recurrence suggesting that targeting these cells may provide eminent benefits in HER2 positive breast cancer patients. Unfortunately, the conventional therapies that target these DCCs are limited. Previous studies from our lab have shown that HER2 peptide pulsed-DC1 (HER2-DC1) vaccine induced 30% complete response (pCR) in DCIS patients. However, little is known about the effect of HER2-DC1 vaccine on DCCs. Here, we investigated the efficacy of HER2-DC1 vaccine on DCCs in a transgenic HER2 mammary cancer model (neuT). The key features of this model are each one of ten mammary glands develops an independent carcinoma that slowly progresses from a microscopic lesion to an invasive tumor and metastasis is mainly driven by DCCs. Since this model mimics some of the most critical features of human disease, we evaluated the efficacy of HER2-DC1 vaccine on DCCs. Mice received six doses of HER2-DC1 vaccine subcutaneously twice a week. The spontaneous tumor development in the mammary glands of NeuT mice was examined once a week by ultrasound until the age of week 16. HER2-DC1 vaccine significantly prevented spontaneous tumor growth in NeuT mice. Remarkably, HER2-DC1 vaccine treatment significantly decreased HER2+CYT8/18+Ki-67+ proliferative DCCs (2%, p&lt;0.002) in the bone marrow (BM-DCCs) compared to untreated mice (6%) by flow cytometry. We also observed increased senescent DCCs (82%, p&lt;0.0001 compared to untreated mice, 37%) by a β-gal assay. BM-DCCs in HER2-DC1 vaccinated mice had reduced expression of Ki-67 compared to untreated mice. Multicolor flow cytometry demonstrated elevated levels of CD4 T cells (2 fold increase) and CD8 T cells (1 fold increase) in the bone marrow after HER2-DC1 vaccination compared to untreated mice. Importantly, accumulation of CD4 T cells (5 fold increase), CD8 T cells (19 fold increase) and B cells (100 fold increase) was observed in the mammary glands of HER2-DC1 vaccinated mice with strong anti-HER2 Th1 immune responses. Notably, HER2-DC1 vaccine led to an increased in the M1 macrophage phenotype (3 fold increase) and decreased M2 type (8 fold decrease) at the tumor site. Treatment of DCCs with Th1 cytokines, IFN-γ or TNF-α significantly induced senescence (76.3%, p&lt;0.0001) in cultured DCCs compared to untreated cells (26%) in vitro. These results describe the novel role of HER2-DC1 vaccine in targeting DCCs and a possible role in prevention of metastasis and recurrence.

Citation Format: Ganesan Ramamoorthi, Krithika Kodumudi, Colin Synder, William Dominguez-Viqueira, Scott Kidd, Shari Pilon-Thomas, Brian Czerniecki. HER2 peptide pulsed dendritic cell vaccine induce senescence and eliminates disseminated cancer cells in a preventive model of transgenic HER2/neu breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1451.

Abstract 4088: Th1 cytokines and oncodriver inhibition: A combination treatment strategy in TNBC

Triple Negative Breast Cancer (TNBC) is characterized by lack of hormone receptors and targeted therapies, resistance to existing treatment and poor survival outcome, highlighting the need for novel therapy development. Oncogene addiction in breast cancer (BC) cells to drive malignancy up presents oncodrivers as promising therapeutic candidates in BC. Our group has shown loss of anti-oncodriver CD4+-T-helper-type-1 (Th1) response in TNBC patients. Here, we studied effects of combination treatment with Th1 cytokines (IFN-γ+TNF-α) and oncodriver blockade in human and mouse TNBC cells (MDA-MB-231, MDA-MB-468, HCC1143, BT549, 4T1). We measured expression of 3 oncodriver proteins: EGFR, HER3 and cMET and observed multiple oncodrivers in majority of the cell lines, suggesting combined oncodriver inhibition may have stronger antitumor effects. Based on oncodriver status, we tested combination treatment with Th1 cytokines and a) monoclonal α-EGFR antibody cetuximab, b) cMET RTK inhibitor crizotinib and c) siRNA inhibition of three oncodrivers. No significant difference in proliferation after IFN-γ or IFN-γ+TNF-α treatment suggested IFN-γ is the primary effector cytokine. IFN-γ alone reduced proliferation &gt;50% in majority of TNBC cells. In EGFRhigh/HER3pos/cMETlow MDA-MB-468, IFN-γ and cetuximab treatment significantly increased apoptosis compared to untreated cells. Combined EGFR and HER3 siRNA inhibition, followed by IFN-γ treatment, increased apoptosis in those cells. In EGFRpos/HER3low/cMEThigh MDA-MB-231 and EGFRlow/HER3high/cMEThigh 4T1, IFN-γ and crizotinib combination significantly decreased proliferation (p&lt;0.0001) compared to single agent. In EGFRpos/HER3pos/cMETpos HCC1143, combined siRNA inhibition of 3 oncodrivers followed by IFN-γ treatment increased apoptotic signal compared to control. Protein expression showed increased STAT1Tyr701 phosphorylation as primary mechanism of IFN-γ mediated proliferation inhibition. Western blot after cetuximab/crizotinib and Th1 cytokines treatment suggests altered phosphorylation of signaling effectors, PI3K/AKT, p44/42MAPK and STATs 1, 3 and 5 may contribute to anti-proliferative, apoptotic effects of combination treatment. siRNA inhibition of one oncodriver resulted in a compensatory increase in expression of the other oncodriver (increased HER3 level in siEGFR transfected MDA-MB-468 cells and vice versa), suggesting a complex signaling crosstalk between oncodrivers in TNBC. We are currently investigating effects of combination treatment on cellular distribution of oncodrivers, % of ALDHpos stem-like cells, cytokines and chemokines secretion profile and protein expression in TNBC cells. Our study suggests combination treatment with Th1 cytokines and oncodriver inhibition in TNBC may contribute to improved therapeutic benefit and clinical outcome.

Citation Format: Amrita Basu, Yongsheng Jia, Krithika Kodumudi, Doris Wiener, Brian Czerniecki. Th1 cytokines and oncodriver inhibition: A combination treatment strategy in TNBC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4088.

Abstract 4434: Th1 cytokines promotes E3 ubiquitin ligase Cullin 5 expression via STAT1 signaling cascade and enhance cul5 mediated proteasomal degradation of HER2 in HER2+/ER- breast cancer

The proto-oncogene HER2/ErbB2 overexpression occurs in 30% of invasive breast cancer patients and its critically associated with aggressive disease, metastasis and tumor recurrence. Despite advances in the treatment of HER2+ breast cancers, resistance and metastatic disease are potential obstacles. Cullin 5 (Cul 5), a scaffold protein mediates formation of the Cullin 5-RING E3 ubiquitin ligase functional complex. This complex acts on protective molecular chaperone heat shock protein (HSP90) complex and subsequently leads to polyubiquitination and proteasomal degradation of its client protein HER2/ErbB2. Reduced expression of Cul 5 in breast cancer patients can abrogates its inhibitory function and favor HSP90 mediated stabilization of HER2/ErbB2. More recently, we showed that Th1 cytokines (IFN-γ and TNF-α) decreased HER2 expression and induced senescence and apoptosis in HER2 overexpressing breast cancer cell lines. However, the role of Th1 cytokines on Cul 5 mediated regulation of HER2/ErbB2 remains unknown. In the present study, low level expression of Cul 5 was observed in various human (SKBR3, HCC1419 and JIMT1) and mouse (Tubo) HER2+/ER- breast cancer cell lines. Interestingly, treatment of HER2+/ER- breast cancer cells with Th1 cytokines increased the expression of Cul 5 and downregulated the expression of HER2. We knocked-down Cul 5 expression by specific siRNA found that treatment of Th1 cytokines failed to decrease HER2 expression in HER2+/ER- breast cancer cells. To investigate whether the mechanism of Th1 cytokines on Cul5 is via downstream signaling molecule STAT-1, we knock-down STAT-1. Silencing of STAT-1 expression prevented Th1 cytokines mediated activation of Cul 5. We also observed no effect on the inhibition of HER2 expression after Th1 cytokines treatment in HER2+/ER- breast cancer cells in which the expression of STAT-1 was knocked-down. Collectively, our findings demonstrate a novel mechanism that Th1 cytokines promote Cul 5 expression via STAT1 signaling and enhance Cul 5 mediated proteasomal degradation of HER2 in HER2+/ER- breast cancer. Enhancing Cul 5 levels may represent a new therapeutic avenue for the inhibition of HER2 overexpression and prevention of metastasis and tumor relapse.

Citation Format: Yongsheng Jia, Ganesan Ramamoorthi, Krithika Kodumudi, Amrita Basu, Doris Wiener, Brian Czerniecki. Th1 cytokines promotes E3 ubiquitin ligase Cullin 5 expression via STAT1 signaling cascade and enhance cul5 mediated proteasomal degradation of HER2 in HER2+/ER- breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4434.

Abstract OT2-04-05: Phase II trial of pre-operative stereotactic ablative radiotherapy (SABR) in early-stage breast cancer

Background:

Post-operative accelerated partial breast irradiation (APBI) has demonstrated efficacy in preventing in-breast tumor recurrence. Pre-operative administration of APBI may be advantageous as an intact breast tumor is smaller than its corresponding lumpectomy cavity, is easier to distinguish on treatment-planning images, and results in smaller and more accurately delineated target volumes. Pre-operative APBI may reduce the incidence of positive margins following breast-conserving surgery (BCS). Investigation is needed in the correlation of MR imaging with pathologic response 6 weeks after SABR. Also, evidence suggests that SABR induces immune activation in the tumor microenvironment; evaluation of excised tumor tissue will give insight into these processes.

Trial Design:

Treatment Planning and Delivery: CT simulation and treatment are performed in the prone position. Diagnostic MRI is fused to planning CT. GTV is delineated on registered breast MRI and includes the intact breast tumor. CTV is 15mm expansion of GTV. PTV is 3 mm expansion of CTV. VMAT or IMRT are permitted. Daily image-guidance aligning to tumor and biopsy-fiducial is mandatory. All subjects undergo pre-operative SABR to 28.5 Gy in 3 fractions of 9.5 Gy on different days separated by ≤48 hours. CTCAE v4 is used to assess toxicity 4-5 weeks after SABR. Pre-operative diagnostic MRI is performed 5-6 weeks following SABR. Imaging parameters to be evaluated include changes in tumor size, enhancement, and tumor margin description. BCS will be 6-8 weeks following SABR.

Tissue pathology: Margin status and degree of pathologic response are recorded from breast-conserving excisions, specimens are archived for future analysis.

Eligibility Criteria:

Inclusion criteria are women age ≥50 with biopsy proven invasive breast adenocarcinoma with tumor size ≤2cm on MRI, cN0 M0, ER+/HER2-, without history of invasive malignancy or prior breast/thoracic radiotherapy.

Exclusion criteria are active scleroderma or lupus erythematosus with skin involvement, MRI defined tumor within 10 mm of skin, implanted hardware prohibiting appropriate treatment planning or delivery, neoadjuvant chemotherapy, carrier of BRCA1 or 2 gene mutation, pregnancy.

Specific Aims:

The primary endpoint is pathologic complete response (pCR) in the breast tumor, secondary endpoints are incidence of adequate surgical margins (defined as “no tumor on ink”) and MRI response following SABR. Analyses of tumor immune response and microenvironment on pathologic specimens following SABR will also be performed.

Statistical Methods:

Fisher's exact test will be performed to examine associations between patient/tumor characteristics and pCR and surgical margins; these associations will be explored with multivariable logistic and linear regressions.

Accrual:

Present accrual is 9 subjects.

Expected accrual is 22 subjects; if ≥3 pCR are noted in the initial cohort, accrual will be expanded to 40 subjects.

Citation Format: Liveringhouse CL, Diaz R, Ahmed KA, Lee MC, Czerniecki B, Laronga C, Khakpour N, Weinfurtner RJ, Rosa M, Montejo ME. Phase II trial of pre-operative stereotactic ablative radiotherapy (SABR) in early-stage breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-04-05.

A cost-utility analysis comparing large volume displacement oncoplastic surgery to mastectomy with free flap reconstruction in the treatment of breast cancer

PURPOSE

Breast cancer surgical treatment may include large volume displacement oncoplastic surgery (LVOS) or mastectomy with free flap reconstruction (MFFR). We investigated the cost-utility between LVOS versus MFFR to determine which approach was most cost-effective.

METHODS

A literature review was performed to calculate probabilities for clinical outcomes for each surgical option (LVOS versus MFFR), and to obtain utility scores that were converted into quality adjusted life years (QALYs) as measures for clinical effectiveness. Average Medicare payments were surrogates for cost. A decision tree was constructed and an incremental cost-utility ratio (ICUR) was used to calculate cost-effectiveness.

RESULTS

The decision tree demonstrates associated QALYs and costs with probabilities used to calculate the ICUR of $3699/QALY with gain of 2.7 QALY at an additional cost of $9987 proving that LVOS is a cost-effective surgical option. One-way sensitivity analysis showed that LVOS became cost-ineffective when its clinical effectiveness had a QALY of less than 30.187. Tornado Diagram Analysis and Monte-Carlo simulation supported our conclusion.

CONCLUSION

LVOS is cost-effective when compared to MFFR for the appropriate breast cancer patient.

CLINICAL QUESTION/LEVEL OF EVIDENCE

II.

A brief report of toxicity end points of HER2 vaccines for the treatment of patients with HER2+ breast cancer

Human epidermal growth factor receptor 2 (HER2)-targeted vaccines are under development, but have so far demonstrated only modest clinical efficacy. Additionally, there has been a lack of adequate safety assessment in large-scale prospective clinical trials. Therefore, we performed a meta-analysis of available clinical trial data to summarize the toxicity profiles of these treatments. Literature search was conducted in February 2018. The trials analyzed had at least one study arm consisting of HER2 vaccine monotherapy. Heterogeneity across studies was analyzed using I² statistics. Data were analyzed using random-effects meta-analysis for absolute risk (AR). Eight trials and 248 patients were included. There was no evidence of heterogeneity between studies for grades 3/4 adverse events (AEs) or for death. The AR for treatment-related serious AEs was 5% with no treatment-related deaths. The AR of all-grade fatigue, injection site reaction, and fever/chills/rigors was 33%, 23%, and 31%, respectively. Asymptomatic drop in left ventricle ejection fraction was rare (8%). HER2 vaccines are well tolerated with increased AR of fatigue, injection site reactions, and fever/chills/rigors.

Abstract 2545: Antitumor efficacy of Type I polarized dendritic cells in combination with immune checkpoint blockade in a preclinical model of breast cancer

Breast cancer is the most commonly diagnosed cancer and a major cause of cancer death among women. Our group has shown progressive loss of the anti-HER2 Th1 immune response in HER2 positive breast cancer patients and administration of peptide-pulsed Type I polarized dendritic cell (DC1) vaccine induced strong anti-HER2 immune response with pathologic complete response rate (pCR) in DCIS (ductal carcinoma in situ) and early invasive breast cancer (IBC). Within the tumor microenvironment, presence of multiple factors, including expression of co-inhibitory immune checkpoint signals has been shown to inhibit anti-tumor immune responses and preventing complete tumor regression. Hence, there is a need to develop strategies that disrupt these negative regulators in the tumor microenvironment in order to achieve robust anti-tumor immune responses. In this study, we investigated whether blockade of immune checkpoints, PD-1 or PD-L1 in combination with DC1 vaccine enhance anti-tumor immune response in a preclinical model of HER2 positive TUBO breast cancer. Balb/c mice received TUBO cells subcutaneously on day 0. Two different treatment regimens were followed to examine anti-tumor efficacy. For regimen-1, TUBO- bearing mice received three doses of p66 (MHC class I) peptide-pulsed DC1 vaccine starting on day 7 at weekly intervals concurrently with intraperitoneal injection of anti-PD-1 or anti-PD-L1 monoclonal antibodies. For regimen-2, starting on day 7 mice received six doses of HER2 specific p66 peptide- pulsed DC1 vaccine twice a week. Monoclonal checkpoint antibodies were given after the last dose of DC1 vaccine. Mice that received DC1 vaccine followed by treatment with anti-PD-1 or anti-PD-L1 monoclonal checkpoint antibodies had significant delay in tumor growth compared to the mice that received DC1 or checkpoint antibodies alone. However, mice that received DC1 in combination with anti-PD-1 antibody had superior efficacy in delayed tumor growth and improved survival rate. TUBO- bearing mice that received regimen-1, with DC1 vaccine and checkpoint antibodies concurrently had no significant delay in the tumor growth compared to mice treated with DC1 alone. Induction of anti-tumor immune response using HER2 specific MHC class II peptide- pulsed DC vaccine in combination with immune checkpoint blockade is ongoing. Overall, these findings suggest that optimal scheduling of immune checkpoint blockade is critical in improving anti-tumor efficacy of DC1 vaccine. This could be a potential combinatorial approach for the treatment of HER2 positive breast cancer in clinical settings.

Citation Format: Krithika N. Kodumudi, Doris Wiener, Amrita Basu, Brian Czerniecki. Antitumor efficacy of Type I polarized dendritic cells in combination with immune checkpoint blockade in a preclinical model of breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2545.

Abstract 826: Th1 cytokines and EGFR inhibition: A combinatorial therapeutic strategy in TNBC

Oncodrivers are a promising target in novel breast cancer therapy development, owing to oncogene addiction of breast cancer cells to sustain their malignancy. We have previously shown progressive loss of CD4+ T-helper type 1 response to oncodrivers in triple negative breast cancer (TNBC) patients. TNBC is marked by lack of cell surface ER, PR and Her2 receptors and is the most aggressive subtype of breast cancer. Lack of therapeutic targets, resistance to existing hormone therapy, metastasis and poor survival in TNBC patients underline the need for novel TNBC therapy development. In this study, we investigated the effect of EGFR inhibitors (cetuximab, erlotinib and lapatinib) alone or combination with Th1 cytokines (IFN-γ and TNF-α) on growth and proliferation of MDA-MB-231 and MDA-MB-468 TNBC cells. We observed decrease in EGFR expression in TNBC cells when treated with IFN-γ alone and in combination with EGFR inhibitors. In addition, IFN-γ alone, in combination with TNF-α and all three EGFR inhibitors, markedly increased STAT1 phosphorylation, indicating suppression of growth and proliferation in TNBC cells. Decreased STAT3 phosphorylation by combination treatment in TNBC cells may induce apoptosis and inhibit proliferation further. Combination of cetuximab and IFN-γ increased cleaved caspase-3 expression in MDA-MB-231, but not in MDA-MB-468 TNBC cells. EGFR inhibition and Th1 cytokine treatment showed combination treatment resulted in severe cell loss and morphological alteration, while Th1 cytokines alone did not induce significant senescence in MDA-MB-231 cells in senescence associated β-galactosidase assay. We are currently investigating activation status of other signaling pathways in TNBC cells, following Th1 cytokines treatment with EGFR inhibition. Our data suggests a combinatorial treatment approach, including DC1 vaccination to elicit Th1 immune response and inhibition of EGFR oncodriver, may lead to an effective and novel therapeutic strategy for triple negative breast cancer.

Citation Format: Amrita Basu, Krithika Kodumudi, Doris Wiener, Brian Czerniecki. Th1 cytokines and EGFR inhibition: A combinatorial therapeutic strategy in TNBC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 826.

Personalized cancer vaccine effectively mobilizes antitumor T cell immunity in ovarian cancer

We conducted a pilot clinical trial testing a personalized vaccine generated by autologous dendritic cells (DCs) pulsed with oxidized autologous whole-tumor cell lysate (OCDC), which was injected intranodally in platinum-treated, immunotherapy-naïve, recurrent ovarian cancer patients. OCDC was administered alone (cohort 1, n = 5), in combination with bevacizumab (cohort 2, n = 10), or bevacizumab plus low-dose intravenous cyclophosphamide (cohort 3, n = 10) until disease progression or vaccine exhaustion. A total of 392 vaccine doses were administered without serious adverse events. Vaccination induced T cell responses to autologous tumor antigen, which were associated with significantly prolonged survival. Vaccination also amplified T cell responses against mutated neoepitopes derived from nonsynonymous somatic tumor mutations, and this included priming of T cells against previously unrecognized neoepitopes, as well as novel T cell clones of markedly higher avidity against previously recognized neoepitopes. We conclude that the use of oxidized whole-tumor lysate DC vaccine is safe and effective in eliciting a broad antitumor immunity, including private neoantigens, and warrants further clinical testing.

Abstract OT2-07-01: Phase 1/2 trial of the oncolytic virus, talimogene laherparpvec, in combination with neoadjuvant chemotherapy in stage II/III triple negative breast cancer

Background: The host anti-tumor immune response plays an important role in determining natural history and therapy response for early stage breast cancer. Tumors with high levels of lymphocytic infiltration appear to have a superior prognosis and response rate to neoadjuvant chemotherapy. However, these tumors are in the minority so methods to enhance tumor lymphocyte infiltration should be identified. The oncolytic virus, talimogene laherparpvec (TVEC) is a genetically modified HSV1 virus which selectively replicates in transformed cells while sparing normal tissue. This leads to lysis of infected tumor cells along with co-expression of GM-CSF to elicit an enhanced anti-tumor immune response. Prior data has shown TVEC can be safely combined with chemotherapy in other indications, so we launched an investigator initiated study to determine the safety and efficacy of combining TVEC with neoadjuvant dose dense chemotherapy in stage II-III TNBC.

Study design: The study is a phase 1 (2 dose levels of TVEC, 3+3 design) and phase 2 single arm Simon two stage combination trial. Primary endpoints of phase 1 is safety of intratumoral TVEC (DL1=106 PFU x 5 injections, DL2=106 PFU x 1 then 108 PFU x 4 injections) administered q2-3 weeks concurrently with weekly paclitaxel followed by standard dose dense AC x 4 and local therapy as indicated. Phase 2 primary endpoint is pCR rate of the study treatment, secondary endpoints include DFS, OS, immune correlates in resected tumor specimens. Eligibility criteria includes females &gt;17 years old, newly diagnosed T2-3N0-3 TNBC, adequate organ function, primary tumor amenable to injection with TVEC, no immunosuppressive or autoimmune conditions, no inflammatory or bilateral/multifocal disease. Sample size is up to 49 patients (12 phase 1, 37 phase 2) with 80% power to detect increase in pCR rate from 30% to 50% with one sided p=.1 in phase 2.

Study status: This novel Amgen supported investigator initiated study activated to accrual 3/2017 and first patient on study was on 5/2017. The study is currently open only at the Moffitt Cancer Center. Target study completion date 8/2021. (NCT02779855)

Citation Format: Soliman HH, Hogue D, Han H, Lee C, Ismail-Khan R, Khong H, Niell B, Czerniecki B. Phase 1/2 trial of the oncolytic virus, talimogene laherparpvec, in combination with neoadjuvant chemotherapy in stage II/III triple negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT2-07-01.

Abstract 3993: Th1 cytokines regulate apoptotic cell death and HER family RTK expression in murine and human breast cancer lines

A recent neoadjuvant vaccine trial to treat early breast cancer demonstrated powerful induction of Th1 immunity against the HER-2, complete pathologic responses in over 18% of subjects, and for many subjects, evidence of down-regulated HER-2 expression on residual disease. To explain these observations, we investigated the action of archetypical Th1 cytokines (TNF-α + IFN-γ) on both murine and human breast cancer cell lines that varied in the surface expression of HER-family receptor tyrosine kinases. We found that most tumor cell lines were sensitive to dual Th1 cytokines as evidenced by lower metabolic activity (alamar blue assay), lower proliferation, and enhanced apoptosis (AnnexinV/PI staining and TUNEL assay) as well as a reversible inhibition of surface expression of HER proteins. Apoptotic cell death was accompanied by demonstrated increases in activated caspase-3. Furthermore, the pharmacologic caspase-3 activator, procaspase-activating compound (PAC-1), mimicked both the killing effects and HER-2 suppressive activities of Th1 cytokines, while the caspase 3/7 inhibitor ((5-[(S)-(+)-2-(Methoxymethyl)pyrrolidino]sulfonylisatin), prevented cytokine-induced HER-2 downregulation. These studies therefore demonstrated that many of the in vivo effects of vaccination (apparent tumor cell death and loss of HER-2 expression) could be replicated in vitro using only the principle Th1 cytokines. These findings are consistent with the notion that IFN-γ and TNF-α work in concert to mediate some of the biological effects of therapeutic Th1-polarizing vaccination through the induction of a caspase 3-dependent cellular death mechanism.

Citation Format: Prachi M. Namjoshi, Lori Showalter, Brian Czerniecki, Gary K. Koski. Th1 cytokines regulate apoptotic cell death and HER family RTK expression in murine and human breast cancer lines. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3993.

Performance and Practice Guideline for the Use of Neoadjuvant Systemic Therapy in the Management of Breast Cancer

PURPOSE

The American Society of Breast Surgeons (ASBrS) sought to provide an evidence-based guideline on the use of neoadjuvant systemic therapy (NST) in the management of clinical stage II and III invasive breast cancer.

METHODS

A comprehensive nonsystematic review was performed of selected peer-reviewed literature published since 2000. The Education Committee of the ASBrS convened to develop guideline recommendations.

RESULTS

A performance and practice guideline was prepared to outline the baseline assessment and perioperative management of patients with clinical stage II-III breast cancer under consideration for NST.

RECOMMENDATIONS

Preoperative or NST is emerging as an important initial strategy for the management of invasive breast cancer. From the surgeon's perspective, the primary goal of NST is to increase the resectability of locally advanced breast cancer, increase the feasibility of breast-conserving surgery and sentinel node biopsy, and decrease surgical morbidity. To ensure optimal patient selection and efficient patient care, the guideline recommends: (1) baseline breast and axillary imaging; (2) minimally invasive biopsies of breast and axillary lesions; (3) determination of tumor biomarkers; (4) systemic staging; (5) care coordination, including referrals to medical oncology, radiation oncology, plastic surgery, social work, and genetic counseling, if indicated; (6) initiation of NST; (7) post-NST breast and axillary imaging; and (8) decision for surgery based on extent of disease at presentation, patient choice, clinical response to NST, and genetic testing results, if performed.

Early postoperative outcomes in lumpectomy versus simple mastectomy

BACKGROUND

Relatively scarce outcomes research exists that compares early postoperative complications between breast conservation surgery (BCS) and simple mastectomy (SM). Such information would improve a surgeon's ability to provide informed consent when considering treatment options, especially for women with early stage breast cancer who have the option to receive either BCS or SM.

MATERIALS AND METHODS

The National Surgical Quality Improvement Program database from years 2009-2012 was analyzed. For each treatment group, we used Current Procedural Terminology codes specific to the treatment modality with sentinel lymph node biopsy as an inclusion criteria. We excluded patients who received axillary lymphadenectomies, bilateral disease or symmetry procedures, and additional breast reconstructive surgery. We compared each group with chi square and two-sample t-tests to look for preoperative comorbidity differences, then used unadjusted odds ratios to compare postoperative complication rates.

RESULTS

Inclusion and exclusion criteria provided 6682 patients in the BCS group and 3339 patients in the SM group. Baseline comorbid condition characteristics showed no clinical differences between groups except for diabetes (8.5% in SM versus 6.5% in BCS). Statistical analysis between each treatment modality revealed that the SM group had significantly higher wound complications, bleeding, infections, and overall complications than the BCS group.

CONCLUSIONS

Although both BCS and SM options have low early postoperative complication rates when treating early stage breast cancer, BCS has fewer complications with regard to bleeding, wound complications and infections.

Abstract 4079: Reversal of immune evasion mediated by HER2 requires both humoral and cellular HER-2 targeted immune interventions

Objectives: HER2 over-expression in breast cancer is associated with a poor prognosis and HER2 is an intense target of immunotherapy with both humoral and T cell -base approaches. HER2 expression is also known to facilitate the escape of tumor cells from immune surveillance by down-regulating MHC class I, resulting in a reduced sensitivity to CTL lysis. Restoring tumor cell MHC Class I expression and reversing their immune evasion are therefore important strategies in the design of immunotherapy against HER2 expressing tumors. In this study we investigated the effects of monoclonal antibody trastuzumab and T help-1 associated cytokines IFN-γ and TNF-A on HLA Class I expression and the susceptibilities to CTL lysis of human HER2 expressing tumor cell lines.

Methods: Breast cancer cell lines MCF7, SKBR3, BT474 and ovarian cancer cell line SKOV3 were treated with trastuzumab only, combination of IFN-γ and TNF-A or trastuzumab with IFN-γ and TNF-A. Cell surface expressions of HLA ABC were examined by flow cytometric analysis. The susceptibility of tumor cells to HER2 specific CD8+ T cell recognition and CTL lysis were assessed by measurement of CD8+ T cell IFN-γ secretion and flow cytometric analysis respectively.

Results: Th1 cytokines IFN-γ and TNF-A dramatically increased HLA ABC expressions on all tumor lines compared to untreated cells, [ MCF7 (p=0.04); SKBR3 (p=0.02); SCOV3 (p=0.02) and BT474 (p=0.04)], while trastuzumab alone showed little impact on HLA ABC up-regulation. When treated with a combination of trastuzumab, IFN-γ and TNF-A tumor cells displayed synergistically enhanced HLA ABC expression [MCF7 (p=0.02); SKBR3 (p=0.004); SKOV3 (0.006) and BT474 (p=0.03)]. We observed that IFN-γ and TNF-A treatment was able to remarkably increase CD8+ T cell recognition and CTL lysis of low and intermediate HER2 expressing tumors [ MCF7(p=0.03) and SKOV3(0.02)], but not High HER2 tumor[ SKBR3(p=0.07)]. Only a combined treatment of trastuzumab, IFN-γ and TNF-A rendered SKBR3 susceptible to a significant killing by CTL (p=0.02). To investigate the impact of other HER family members EGFR and HER3 on MHC class I expression , HER2 over-expressing breast cancer cell lines BT474 and SKBR3 were pre-treated with EGF or Heregulin, then subjected to IFN-γ and TNF-A treatments. Activation of HER1 and HER3 signaling made HER2 over-expressing cells resistant to the effect of MHC class I up-regulation by IFN-γ and TNF-A.

Conclusion: Both humoral and cellular immune HER-2 targeted interventions are required to reverse immune escape mediated by HER2; in addition to targeting HER2, targeting HER1 and HER3 signaling elements should also be included in order to abrogate the cross talk between HER family members and more effectively inhibit the HER2 signaling pathway.

Citation Format: Shuwen Xu, Jessica Cintolo, Jashodeep Datta, Cinthia Rosemblit, Erik Berk, Julia Terhune, Elizabeth Fitzpatrick, Brian Czerniecki. Reversal of immune evasion mediated by HER2 requires both humoral and cellular HER-2 targeted immune interventions. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4079. doi:10.1158/1538-7445.AM2014-4079

Linear synthetic peptides induce anti-HER-2 antibody responses with Trastuzumab- (Herceptin) like biological activity (P4308)

The monoclonal antibody Trastuzumab, which recognizes a conformation-dependent epitope on the extracellular domain of HER-2, has revolutionized the treatment of HER-2pos breast cancers. High costs and short half-life of Trastuzumab spurs the search for ways to induce therapeutic anti-HER-2 antibodies in vivo. Linear T cell epitopes have already been discovered for HER-2, and these have shown promise in vaccine studies where strong cell-mediated responses have been generated. Identifying conformation-independent B cell epitopes would allow the construction of linear T-B vaccine constructs that would generate both cellular and humoral anti-HER-2 responses with potential anti-cancer activity. We produced a synthetic peptide library consisting of 62 overlapping 20-mers spanning the HER-2 extracellular domain. These were used to vaccinate Balb/c mice. Resulting antisera were screened for reactivity against peptide and recombinant extracellular domain protein via ELISA, and whole native protein by immuno-fluorescent microscopy and FACS analysis. Sera reactive by all these criteria were compared with Trastuzumab for ability to disrupt HER-2 and HER-2/HER-3 dimer signaling with and without heregulin. We identified linear peptides that induced antibodies capable of blocking AKT as well as HER-3 phosphorylation in breast cancer lines similar to Trastuzumab. This suggests that a linear epitope/vaccination approach may be feasible for generating effective anti-HER-2 antibody responses.