Neutrophil Elastase Remodels Mammary Tumors to Facilitate Lung Metastasis

Metastatic disease remains the leading cause of death due to cancer, yet the mechanism(s) of metastasis and its timely detection remain to be elucidated. Neutrophil elastase (NE), a serine protease secreted by neutrophils, is a crucial mediator of chronic inflammation and tumor progression. In this study, we used the PyMT model (NE+/+ and NE-/-) of breast cancer to interrogate the tumor-intrinsic and -extrinsic mechanisms by which NE can promote metastasis. Our results showed that genetic ablation of NE significantly reduced lung metastasis and improved metastasis-free survival. RNA-sequencing analysis of primary tumors indicated differential regulation of tumor-intrinsic actin cytoskeleton signaling pathways by NE. These NE-regulated pathways are critical for cell-to-cell contact and motility and consistent with the delay in metastasis in NE-/- mice. To evaluate whether pharmacologic inhibition of NE inhibited pulmonary metastasis and phenotypically mimicked PyMT NE-/- mice, we utilized AZD9668, a clinically available and specific NE inhibitor. We found AZD9668 treated PyMT-NE+/+ mice showed significantly reduced lung metastases, improved recurrence-free, metastasis-free and overall survival, and their tumors showed similar molecular alterations as those observed in PyMT-NE-/- tumors. Finally, we identified a NE-specific signature that predicts recurrence and metastasis in patients with breast cancer. Collectively, our studies suggest that genetic ablation and pharmacologic inhibition of NE reduces metastasis and extends survival of mouse models of breast cancer, providing rationale to examine NE inhibitors as a treatment strategy for the clinical management of patients with metastatic breast cancer.

The Spectrum of Non-neoplastic Changes Associated With Breast Implants: Histopathology, Imaging, and Clinical Significance

Breast implant-associated anaplastic large cell lymphoma has been recognized as a distinct entity in the World Health Organization classification of hematolymphoid neoplasms. These neoplasms are causally related to textured implants that were used worldwide until recently. Consequently, there is an increased demand for processing periprosthetic capsules, adding new challenges for surgeons, clinicians, and pathologists. In the literature, the focus has been on breast implant-associated anaplastic large cell lymphoma; however, benign complications related to the placement of breast implants occur in up to 20% to 30% of patients. Imaging studies are helpful in assessing patients with breast implants for evidence of implant rupture, changes in tissues surrounding the implants, or regional lymphadenopathy related to breast implants, but pathologic examination is often required. In this review, we couple our experience with a review of the literature to describe a range of benign lesions associated with breast implants that can be associated with different clinical presentations or pathogenesis and that may require different diagnostic approaches. We illustrate the spectrum of the most common of these benign disorders, highlighting their clinical, imaging, gross, and microscopic features. Finally, we propose a systematic approach for the diagnosis and handling of breast implant specimens in general.

Endocrine-Sensitive Disease Rate in Postmenopausal Patients With Estrogen Receptor-Rich/ERBB2-Negative Breast Cancer Receiving Neoadjuvant Anastrozole, Fulvestrant, or Their Combination: A Phase 3 Randomized Clinical Trial

Importance

Adding fulvestrant to anastrozole (A+F) improved survival in postmenopausal women with advanced estrogen receptor (ER)-positive/ERBB2 (formerly HER2)-negative breast cancer. However, the combination has not been tested in early-stage disease.

Objective

To determine whether neoadjuvant fulvestrant or A+F increases the rate of pathologic complete response or ypT1-2N0/N1mic/Ki67 2.7% or less residual disease (referred to as endocrine-sensitive disease) over anastrozole alone.

Design, Setting, and Participants

A phase 3 randomized clinical trial assessing differences in clinical and correlative outcomes between each of the fulvestrant-containing arms and the anastrozole arm. Postmenopausal women with clinical stage II to III, ER-rich (Allred score 6-8 or >66%)/ERBB2-negative breast cancer were included. All analyses were based on data frozen on March 2, 2023.

Interventions

Patients received anastrozole, fulvestrant, or a combination for 6 months preoperatively. Tumor Ki67 was assessed at week 4 and optionally at week 12, and if greater than 10% at either time point, the patient switched to neoadjuvant chemotherapy or immediate surgery.

Main Outcomes and Measures

The primary outcome was the endocrine-sensitive disease rate (ESDR). A secondary outcome was the percentage change in Ki67 after 4 weeks of neoadjuvant endocrine therapy (NET) (week 4 Ki67 suppression).

Results

Between February 2014 and November 2018, 1362 female patients (mean [SD] age, 65.0 [8.2] years) were enrolled. Among the 1298 evaluable patients, ESDRs were 18.7% (95% CI, 15.1%-22.7%), 22.8% (95% CI, 18.9%-27.1%), and 20.5% (95% CI, 16.8%-24.6%) with anastrozole, fulvestrant, and A+F, respectively. Compared to anastrozole, neither fulvestrant-containing regimen significantly improved ESDR or week 4 Ki67 suppression. The rate of week 4 or week 12 Ki67 greater than 10% was 25.1%, 24.2%, and 15.7% with anastrozole, fulvestrant, and A+F, respectively. Pathologic complete response/residual cancer burden class I occurred in 8 of 167 patients and 17 of 167 patients, respectively (15.0%; 95% CI, 9.9%-21.3%), after switching to neoadjuvant chemotherapy due to week 4 or week 12 Ki67 greater than 10%. PAM50 subtyping derived from RNA sequencing of baseline biopsies available for 753 patients (58%) identified 394 luminal A, 304 luminal B, and 55 nonluminal tumors. A+F led to a greater week 4 Ki67 suppression than anastrozole alone in luminal B tumors (median [IQR], -90.4% [-95.2 to -81.9%] vs -76.7% [-89.0 to -55.6%]; P < .001), but not luminal A tumors. Thirty-six nonluminal tumors (65.5%) had a week 4 or week 12 Ki67 greater than 10%.

Conclusions and Relevance

In this randomized clinical trial, neither fulvestrant nor A+F significantly improved the 6-month ESDR over anastrozole in ER-rich/ERBB2-negative breast cancer. Aromatase inhibition remains the standard-of-care NET. Differential NET response by PAM50 subtype in exploratory analyses warrants further investigation.

Trial Registration

ClinicalTrials.gov Identifier: NCT01953588.

Breast Implant Associated Anaplastic Large Cell Lymphoma: Evidence-Based Consensus Conference Statement From The American Association of Plastic Surgeons

BACKGROUND

In the absence of high-quality evidence, there is a need to provide guidelines and multidisciplinary consensus recommendations on Breast Implant-Associated Anaplastic Large Cell Lymphoma (BIA-ALCL). The purpose of this expert consensus conference was to evaluate the existing evidence regarding the diagnosis, and management of BIA-ALCL caused by textured implants. The aim is to provide evidence-based recommendations regarding the management and prevention of BIA-ALCL.

METHODS

A comprehensive search was conducted in the MEDLINE, Cochrane Library, and Embase databases, supplemented by manual searches of relevant English language articles and "related articles" sections. Studies focusing on breast surgery and lymphoma associated with breast implants were included for analysis. Meta-analyses were performed and reviewed by experts selected by the American Association of Plastic Surgeons by a Delphi consensus method.

RESULTS

840 articles between January 2011 and January 2023 were initially identified and screened. Full-text of 188 articles were assessed. An additional 43 articles were excluded for focus, and 145 articles were included in the synthesis of results, with 105 of them being case reports or case series. The analysis encompassed a comprehensive examination of the selected articles to determine the incidence, risk factors, clinical presentation, diagnostic approaches, and treatment modalities related to BIA-ALCL.

CONCLUSIONS

Plastic surgeons should be aware of the elevated risks by surface type, implement appropriate patient surveillance, and follow the recommendations outlined in this statement to ensure patient safety and optimize outcomes. Ongoing research on pathogenesis, genetic drivers, and preventative and prophylactic measures is crucial for improving patient care.

High Community-Level Social Vulnerability is Associated with Worse Recurrence-Free Survival (RFS) After Resection of Extremity and Truncal Soft Tissue Sarcoma

BACKGROUND

Although social vulnerability has been associated with worse postoperative and oncologic outcomes in other cancer types, these effects have not been characterized in patients with soft tissue sarcoma. This study evaluated the association of social vulnerability and oncologic outcomes.

METHODS

The authors conducted a single-institution cohort study of adult patients with primary and locally recurrent extremity or truncal soft tissue sarcoma undergoing resection between January 2016 and December 2021. The social vulnerability index (SVI) was measured on a low (SVI 1-39%, least vulnerable) to high (60-100%, most vulnerable) SVI scale. The association of SVI with overall survival (OS) and recurrence-free survival (RFS) was evaluated by Kaplan-Meier analysis and Cox proportional hazard regression.

RESULTS

The study identified 577 patients. The median SVI was 44 (interquartile range [IQR], 19-67), with 195 patients categorized as high SVI and 265 patients as low SVI. The median age, tumor size, histologic subtype, grade, comorbidities, stage, follow-up time, and perioperative chemotherapy and radiation utilization were similar between the high and low SVI cohorts. The patients with high SVI had worse OS (p = 0.07) and RFS (p = 0.016) than the patients with low SVI. High SVI was independently associated with shorter RFS in the multivariate analysis (hazard ratio, 1.64; 95% confidence interval, 1.06-2.54) but not with OS (HR, 1.47; 95% CI 0.84-2.56).

CONCLUSION

High community-level social vulnerability appears to be independently associated with worse RFS for patients undergoing resection of extremity and truncal soft tissue sarcoma. The effect of patient and community-level social risk factors should be considered in the treatment of patients with extremity sarcoma.

Axillary Nodal Metastases Conversion and Perioperative Complications with Neoadjuvant Pembrolizumab Therapy in Triple-Negative Breast Cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is known to portend a worse prognosis compared with same-stage, hormone receptor-positive disease. However, with the recent change in practice to include pembrolizumab in neoadjuvant chemotherapy (NAC) for TNBC, an increase in pathologic complete responses (pCRs) has been reported. The perioperative repercussions of adding pembrolizumab to standard NAC regimens for TNBC are currently unknown. We aimed to explore the perioperative implications of adding pembrolizumab to standard NAC regimens for non-metastatic TNBC.

METHODS

This was a retrospective review of the perioperative outcomes in patients with non-metastatic TNBC treated with pembrolizumab-NAC from January 2018 to October 2022 conducted at a high-volume cancer center. Patient demographics, comorbidities, clinical and pathological staging, NAC treatment regimen, initiation, and completion, as well as date of surgery and postoperative complications were analyzed.

RESULTS

Of 87 patients, 67.8% had an overall pCR and 86% had an axillary pCR; 37.2% of cN+ patients were spared from axillary lymph node dissection. However, 24.1% of patients experienced surgical complications, 9% of patients were receiving steroids at the time of breast surgery secondary to adverse effects of pembrolizumab-NAC, and 7% underwent a change in the initial surgical plan such as omission of reconstruction.

CONCLUSION

Pembrolizumab-NAC has not only significant oncologic benefit but also noteworthy perioperative implications in the surgical management of TNBC.

Diffusion Tensor Imaging for Characterizing Changes in Triple-Negative Breast Cancer During Neoadjuvant Systemic Therapy

BACKGROUND

Assessment of treatment response in triple-negative breast cancer (TNBC) may guide individualized care for improved patient outcomes. Diffusion tensor imaging (DTI) measures tissue anisotropy and could be useful for characterizing changes in the tumors and adjacent fibroglandular tissue (FGT) of TNBC patients undergoing neoadjuvant systemic treatment (NAST).

PURPOSE

To evaluate the potential of DTI parameters for prediction of treatment response in TNBC patients undergoing NAST.

STUDY TYPE

Prospective.

POPULATION

Eighty-six women (average age: 51 ± 11 years) with biopsy-proven clinical stage I-III TNBC who underwent NAST followed by definitive surgery. 47% of patients (40/86) had pathologic complete response (pCR).

FIELD STRENGTH/SEQUENCE

3.0 T/reduced field of view single-shot echo-planar DTI sequence.

ASSESSMENT

Three MRI scans were acquired longitudinally (pre-treatment, after 2 cycles of NAST, and after 4 cycles of NAST). Eleven histogram features were extracted from DTI parameter maps of tumors, a peritumoral region (PTR), and FGT in the ipsilateral breast. DTI parameters included apparent diffusion coefficients and relative diffusion anisotropies. pCR status was determined at surgery.

STATISTICAL TESTS

Longitudinal changes of DTI features were tested for discrimination of pCR using Mann-Whitney U test and area under the receiver operating characteristic curve (AUC). A P value <0.05 was considered statistically significant.

RESULTS

47% of patients (40/86) had pCR. DTI parameters assessed after 2 and 4 cycles of NAST were significantly different between pCR and non-pCR patients when compared between tumors, PTRs, and FGTs. The median surface/average anisotropy of the PTR, measured after 2 and 4 cycles of NAST, increased in pCR patients and decreased in non-pCR patients (AUC: 0.78; 0.027 ± 0.043 vs. -0.017 ± 0.042 mm2 /s).

DATA CONCLUSION

Quantitative DTI features from breast tumors and the peritumoral tissue may be useful for predicting the response to NAST in TNBC.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 4.

Exploring Novel Frontiers: Leveraging STAT3 Signaling for Advanced Cancer Therapeutics

Signal Transducer and Activator of Transcription 3 (STAT3) plays a significant role in diverse physiologic processes, including cell proliferation, differentiation, angiogenesis, and survival. STAT3 activation via phosphorylation of tyrosine and serine residues is a complex and tightly regulated process initiated by upstream signaling pathways with ligand binding to receptor and non-receptor-linked kinases. Through downstream deregulation of target genes, aberrations in STAT3 activation are implicated in tumorigenesis, metastasis, and recurrence in multiple cancers. While there have been extensive efforts to develop direct and indirect STAT3 inhibitors using novel drugs as a therapeutic strategy, direct clinical application remains in evolution. In this review, we outline the mechanisms of STAT3 activation, the resulting downstream effects in physiologic and malignant settings, and therapeutic strategies for targeting STAT3. We also summarize the pre-clinical and clinical evidence of novel drug therapies targeting STAT3 and discuss the challenges of establishing their therapeutic efficacy in the current clinical landscape.

Standardization of Colon Resection for Cancer: An Overview of the American College of Surgeons Commission on Cancer Standard 5.6

The purpose of this editorial is to review the American College of Surgeons Commission on Cancer Standard 5.6, which pertains to curative intent colon resections performed for cancer. We first provide a broad overview of the Operative Standard, followed by the underlying rationale, technical components, and documentation requirements.

Evaluation of a Surgical Navigation System for Localization and Excision of Nonpalpable Lesions in Breast and Axillary Surgery

Introduction

Elucent Medical has introduced a novel EnVisio™ Surgical Navigation system which uses SmartClips™ that generate a unique electromagnetic signal triangulated in 3 dimensions for real-time navigation. The purpose of this study was to evaluate the efficacy and feasibility of the EnVisio Surgical Navigation system in localizing and excising nonpalpable lesions in breast and axillary surgery.

Methods

This pilot study prospectively examined patients undergoing breast and nodal localization using the EnVisio Surgical Navigation system. SmartClips were placed by designated radiologists using ultrasound (US) or mammographic (MMG) guidance. The technical evaluation focused on successful deployment and subsequent excision of all localized lesions including SmartClips and biopsy clips.

Results

Eleven patients underwent localization using 27 SmartClips which included bracketed multifocal disease (n = 4) and clipped lymph node (n = 1). The bracketed cases were each localized with 2 SmartClips. Mammography and ultrasound were used (n = 8 and n = 19, respectively) to place the SmartClips. All 27 devices were successfully deployed within 5 mm of the targeted lesion or biopsy clip. All SmartClip devices were identified and retrieved intraoperatively. No patients required a second operation for margin excision.

Conclusion

In a limited sample, the EnVisio Surgical Navigation system was a reliable technology for the localization of breast and axillary lesions planned for surgical excision. Further comparative studies are required to evaluate its efficacy in relation to the other existing localization modalities.

Extremely Low Incidence of Local-Regional Recurrences Observed Among T1-2 N1 (1 or 2 Positive SLNs) Breast Cancer Patients Receiving Upfront Mastectomy Without Completion Axillary Node Dissection

BACKGROUND

Completion axillary node dissection (CLND) is routinely omitted in cT1-2 N0 breast cancer treated with upfront, breast-conserving therapy and sentinel node biopsy (SLNB) showing one to two positive sentinel nodes (SLNs). The purpose of this study was to determine the incidence and impact of axillary treatment among patients treated with mastectomy in a contemporary cohort.

METHODS

A prospective, institutional database was reviewed from 2006 to 2015 to identify patients with T1-2 breast cancer treated with upfront mastectomy and SLNB found to have one to two positive SLNs. Patients were stratified by axillary therapy [including CLND and/or post-mastectomy radiation therapy (PMRT)], and clinicopathologic factors and incidence rates of local-regional and distant recurrence were analyzed.

RESULTS

A total of 548 patients were identified, including 126 (23%) without CLND. Rates of PMRT were similar between those with and without CLND (35.3% vs. 28.6%, p = 0.16). On multivariate analysis, two rather than one positive SLN, larger SLN metastasis size, frozen-section analysis of the SLNB, and adjuvant chemotherapy were significantly associated with receipt of CLND. At a median follow-up of 7 years, there were only two local-regional recurrences in the no-CLND group, of which only one was an axillary recurrence. The 5-years incidence rate of LRR was not significantly different for those with and without CLND (1.3% vs. 1.8%, p = 0.93).

CONCLUSIONS

We found extremely low rates of local-regional recurrence among those with T1-2 breast cancer undergoing upfront mastectomy with 1-2 positive SLNs. Further axillary surgery may not be indicated in selected patients treated with a multidisciplinary approach, including adjuvant therapies.

Longitudinal dynamic contrast-enhanced MRI radiomic models for early prediction of response to neoadjuvant systemic therapy in triple-negative breast cancer

Early prediction of neoadjuvant systemic therapy (NAST) response for triple-negative breast cancer (TNBC) patients could help oncologists select individualized treatment and avoid toxic effects associated with ineffective therapy in patients unlikely to achieve pathologic complete response (pCR). The objective of this study is to evaluate the performance of radiomic features of the peritumoral and tumoral regions from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) acquired at different time points of NAST for early treatment response prediction in TNBC. This study included 163 Stage I-III patients with TNBC undergoing NAST as part of a prospective clinical trial (NCT02276443). Peritumoral and tumoral regions of interest were segmented on DCE images at baseline (BL) and after two (C2) and four (C4) cycles of NAST. Ten first-order (FO) radiomic features and 300 gray-level-co-occurrence matrix (GLCM) features were calculated. Area under the receiver operating characteristic curve (AUC) and Wilcoxon rank sum test were used to determine the most predictive features. Multivariate logistic regression models were used for performance assessment. Pearson correlation was used to assess intrareader and interreader variability. Seventy-eight patients (48%) had pCR (52 training, 26 testing), and 85 (52%) had non-pCR (57 training, 28 testing). Forty-six radiomic features had AUC at least 0.70, and 13 multivariate models had AUC at least 0.75 for training and testing sets. The Pearson correlation showed significant correlation between readers. In conclusion, Radiomic features from DCE-MRI are useful for differentiating pCR and non-pCR. Similarly, predictive radiomic models based on these features can improve early noninvasive treatment response prediction in TNBC patients undergoing NAST.

Abemaciclib Is Effective in Palbociclib-Resistant Hormone Receptor-Positive Metastatic Breast Cancers

Cyclin-dependent kinases 4/6 inhibitor (CDK4/6i) plus endocrine therapy (ET) is standard of care for patients with hormone receptor (HR)-positive, HER2-negative metastatic breast cancer (MBC). However, resistance to CDK4/6is plus ET remains a clinical problem with limited therapeutic options following disease progression. Different CDK4/6is might have distinct mechanisms of resistance, and therefore using them sequentially or targeting their differentially altered pathways could delay disease progression. To understand pathways leading to resistance to the CDK4/6is palbociclib and abemaciclib, we generated multiple in vitro models of palbociclib-resistant (PR) and abemaciclib-resistant (AR) cell lines as well as in vivo patient-derived xenografts (PDX) and ex vivo PDX-derived organoids (PDxO) from patients who progressed on CDK4/6i. PR and AR breast cancer cells exhibited distinct transcriptomic and proteomic profiles that sensitized them to different classes of inhibitors; PR cells upregulated G2-M pathways and responded to abemaciclib, while AR cells upregulated mediators of the oxidative phosphorylation pathway (OXPHOS) and responded to OXPHOS inhibitors. PDX and organoid models derived from patients with PR breast cancer remained responsive to abemaciclib. Resistance to palbociclib while maintaining sensitivity to abemaciclib was associated with pathway-specific transcriptional activity but was not associated with any individual genetic alterations. Finally, data from a cohort of 52 patients indicated that patients with HR-positive/HER2-negative MBC who progressed on palbociclib-containing regimens can exhibit a meaningful overall clinical benefit from abemaciclib-based therapy when administered after palbociclib. These findings provide the rationale for clinical trials evaluating the benefit of abemaciclib treatment following progression on a prior CDK4/6i.

SIGNIFICANCE

Palbociclib-resistant breast cancers respond to abemaciclib and express pathway-specific signatures of sensitivity, providing a biomarker-driven therapeutic option for patients with metastatic breast cancer following disease progression on cyclin-dependent kinases 4/6 inhibitors.

Deep Learning for Fully Automatic Tumor Segmentation on Serially Acquired Dynamic Contrast-Enhanced MRI Images of Triple-Negative Breast Cancer

Accurate tumor segmentation is required for quantitative image analyses, which are increasingly used for evaluation of tumors. We developed a fully automated and high-performance segmentation model of triple-negative breast cancer using a self-configurable deep learning framework and a large set of dynamic contrast-enhanced MRI images acquired serially over the patients' treatment course. Among all models, the top-performing one that was trained with the images across different time points of a treatment course yielded a Dice similarity coefficient of 93% and a sensitivity of 96% on baseline images. The top-performing model also produced accurate tumor size measurements, which is valuable for practical clinical applications.

Multi-disciplinary management of recurrent gastrointestinal stromal tumor harboring KIT exon 11 mutation with the switch-control kinase inhibitor ripretinib and surgery

Ripretinib is a tyrosine kinase inhibitor that was approved by the United States FDA in 2020 for treatment of advanced gastrointestinal stromal tumor (GIST) in patients who received prior treatment with three or more tyrosine kinase inhibitors. In this case report, we show the durable clinical benefit achieved in a patient with GIST by using ripretinib and repeated timely surgical resection of limited disease progression. The total time on ripretinib was 43 months which is longer than the current reported data from ripretinib clinical trials. Such approach for using multi-disciplinary disease management can improve the durability of response to tyrosine kinase inhibitors, including ripretinib, and associated clinical outcomes.

Intraoperative Fluorescence Guidance for Breast Cancer Lumpectomy Surgery

Fluorescence Guidance for Lumpectomy SurgeryThis prospective trial of 406 patients assessed margin status with and without pegulicianine fluorescence-guided surgery (pFGS) for stages 0 to 3 breast cancers. The use of pFGS met prespecified thresholds for removal of residual tumor and specificity but did not meet the prespecified threshold for sensitivity.

Predicting pathological complete response to neoadjuvant systemic therapy for triple-negative breast cancers using deep learning on multiparametric MRIs

We trained and validated a deep learning model that can predict the treatment response to neoadjuvant systemic therapy (NAST) for patients with triple negative breast cancer (TNBC). Dynamic contrast enhanced (DCE) MRI and diffusion-weighted imaging (DWI) of the pre-treatment (baseline) and after four cycles (C4) of doxorubicin/cyclophosphamide treatment were used as inputs to the model for prediction of pathologic complete response (pCR). Based on the standard pCR definition that includes disease status in either breast or axilla, the model achieved areas under the receiver operating characteristic curves (AUCs) of 0.96 ± 0.05, 0.78 ± 0.09, 0.88 ± 0.02, and 0.76 ± 0.03, for the training, validation, testing, and prospective testing groups, respectively. For the pCR status of breast only, the retrained model achieved prediction AUCs of 0.97 ± 0.04, 0.82 ± 0.10, 0.86 ± 0.03, and 0.83 ± 0.02, for the training, validation, testing, and prospective testing groups, respectively. Thus, the developed deep learning model is highly promising for predicting the treatment response to NAST of TNBC.Clinical Relevance- Deep learning based on serial and multiparametric MRIs can potentially distinguish TNBC patients with pCR from non-pCR at the early stage of neoadjuvant systemic therapy, potentially enabling more personalized treatment of TNBC patients.

Local Recurrence After Breast-Conserving Therapy in Patients With Multiple Ipsilateral Breast Cancer: Results From ACOSOG Z11102 (Alliance)

PURPOSE

Breast-conserving therapy (BCT) is the preferred treatment for unifocal breast cancer (BC). The oncologic safety of BCT for multiple ipsilateral breast cancer (MIBC) has not been demonstrated in a prospective study. ACOSOG Z11102 (Alliance) is a phase II, single-arm, prospective trial designed to evaluate oncologic outcomes in patients undergoing BCT for MIBC.

PATIENTS AND METHODS

Women age 40 years and older with two to three foci of biopsy-proven cN0-1 BC were eligible. Patients underwent lumpectomies with negative margins followed by whole breast radiation with boost to all lumpectomy beds. The primary end point was cumulative incidence of local recurrence (LR) at 5 years with an a priori rate of clinical acceptability of <8%.

RESULTS

Among 270 women enrolled between November 2012 and August 2016, there were 204 eligible patients who underwent protocol-directed BCT. The median age was 61 years (range, 40-87 years). At a median follow-up of 66.4 months (range, 1.3-90.6 months), six patients developed LR for an estimated 5-year cumulative incidence of LR of 3.1% (95% CI, 1.3 to 6.4). Patient age, number of sites of preoperative biopsy-proven BC, estrogen receptor status and human epidermal growth factor receptor 2 status, and pathologic T and N categories were not associated with LR risk. Exploratory analysis showed that the 5-year LR rate in patients without preoperative magnetic resonance imaging (MRI; n = 15) was 22.6% compared with 1.7% in patients with a preoperative MRI (n = 189; P = .002).

CONCLUSION

The Z11102 clinical trial demonstrates that breast-conserving surgery with adjuvant radiation that includes lumpectomy site boosts yields an acceptably low 5-year LR rate for MIBC. This evidence supports BCT as a reasonable surgical option for women with two to three ipsilateral foci, particularly among patients with disease evaluated with preoperative breast MRI.

Abstract 308: Low molecular weight cyclin E deregulates DNA replication and damage repair to promote genomic instability in breast cancer

Background: Low molecular weight cyclin E (LMW-E) are oncogenic forms of cyclin E that are post translationally generated from the full-length cyclin E1 (FL-cycE). LMW-E is detected in breast cancer cells and tumor tissues, but not in normal mammary epithelial cells or adjacent normal tissues. Unlike FL-cycE, LMW-E drives mammary epithelial cell transformation in human cells and spontaneous mammary tumor formation in transgenic mouse models, but the oncogenic mechanisms of LMW-E and its unique function(s) independent of FL-cycE are not fully understood. It is currently assumed that LMW-E drives the tumorigenic process by promoting G1/S cell cycle transition and accelerating mitotic exit. Biochemical features such as longer protein half-life, higher affinity to its kinase partner CDK2, and resistance to endogenous CDK inhibitors such as p21 and p27 all promote the tumorigenic ability of LMW-E. Clinical studies in breast cancer reveal that overexpression of LMW-E predicts recurrence and poor survival in breast cancer patients independent of molecular subtype, Ki67 status, nodal status, or tumor grade, suggesting LMW-E may drive breast cancer development independent of its role in cell proliferation. In the current study, we tested the hypothesis that LMW-E promotes genomic instability by deregulating DNA replication and damage repair.

Results: We generated immortalized pre-cancerous human mammary epithelial cells (hMECs) to express doxycycline inducible LMW-E or FL-cycE in CCNE1 knock-out background. We found that FL-cycE overexpression led to DNA replication stress and DNA damage accumulation, resulting in reduced cell viability. LMW-E overexpression, on the other hand, promoted cell survival under replication stress, resulting in persistent genomic instability. RNA-sequencing results showed LMW-E but not FL-cycE overexpression enhanced DNA replication and damage repair pathways. Molecularly, LMW-E interacted with and facilitated pre-replication complex assembly. LMW-E also mediated DNA repair by upregulating RAD51 and C17orf53, showing a dominant repairing effect over DNA damage induced by FL-cycE. Moreover, targeting the replication stress response pathway ATR-CHK1-RAD51 with small molecule inhibitors significantly decreased viability of LMW-E overexpressing hMECs and breast cancer cells. Lastly, we showed that positive LMW-E status was associated with genomic instability in tumors from a cohort of 725 patients diagnosed with early-stage breast cancer, further supporting our hypothesis that LMW-E promotes genomic instability to fuel breast cancer development.

Conclusions: Collectively, our findings delineated a novel role for LMW-E in breast tumorigenesis mediated by replication stress tolerance and genomic instability, providing novel therapeutic strategies for LMW-E overexpressing breast cancers.

Citation Format: Mi Li, Spiridon Tsavachidis, Fuchenchu Wang, Tuyen Bui, Tuyen D. Nguyen, Linjie Luo, Asha S. Multani, Melissa L. Bondy, Kelly K. Hunt, Khandan Keyomarsi. Low molecular weight cyclin E deregulates DNA replication and damage repair to promote genomic instability in 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 308.

Abstract 950: Targeting PKMYT1 kinase is an effective treatment strategy in triple negative breast cancers with low molecular weight cyclin E (LMW-E) expression

Background: Cyclin E is post-translationally modified by neutrophil elastase mediated proteolytic cleavage to generate the low molecular weight isoforms of cyclin E (LMW-E) that are detected in various human cancers. We previously reported that 70% of triple negative breast cancers (TNBC) examined overexpress LMW-E, and these patients have a poor prognosis. Expression of LMW-E promotes genomic instability by causing DNA replication stress. PKMYT1 prevents premature mitotic entry by catalyzing CDK1 phosphorylation at T14, essential for preventing DNA damage and cell death when cyclin E, including LMW-E, is overexpressed. In this study, we tested the hypothesis that LMW-E positive status can be used as a biomarker of response in selecting TNBC patients who are likely to respond to RP-6306, a first in-class and selective inhibitor of PKMYT1 kinase.

Results: Assessment of pre-treatment breast biopsies from TNBC patients (n=40) enrolled in a neoadjuvant chemotherapy prospective study for LMW-E and CDK1-pT14 revealed significant positive correlation between these two proteins. Furthermore, positivity of both biomarkers was associated with lack of pathologic complete response (pCR) to neoadjuvant chemotherapy. We next examined the mechanism of response to RP-6306 in vitro and in vivo using TNBC cell lines, patient-derived xenograft (PDX) models and transgenic mouse mammary tumor virus (MMTV) models expressing human LMW-E (hLMW-E). In vitro results using 7 different TNBC cell lines, revealed that high LMW-E levels are significantly predictive of response to RP-6306 (R2=0.78, p= 0.008), while LMW-E knockdown resulted in a 7X increase in IC50 values of RP-6306 (p&lt;0.001). In high LMW-E cells, treatment with RP-6306 resulted in significant (i) downregulation of CDK1-pT14, PKMYT1, WEE1, cyclin B and pRb, (ii) accumulation of sub-G1 and polyploid cell population, (iii) apoptosis, (iv) accumulation of chromosomal breakage, (v) increased DNA damage (increase in γ-H2AX and 53BP1 foci/cell) and lack of DNA repair (downregulation of Rad51), and (vi) premature mitotic entry. Treatment of both breast cancer PDX models and hLMW-E transgenic tumors with RP-6306 revealed that only in animals with high LMW-E tumors, treatment results in significant decrease in tumor volume. However, RP-6306 was ineffective in reducing tumor volume in low cyclin E in vivo models. Immunohistochemical analysis revealed that in vivo efficacy of RP-6306 (in both PDX and transgenic models) was concomitant with increase in γ-H2AX and decrease in CDK1-pT14 and Ki67.

Conclusion: Collectively, our results show that overexpression of LMW-E and CDK1-pT14 in TNBC can be used to stratify patients whose tumors are likely to respond to RP-6306. Mechanistically, LMW-E overexpressing TNBC cells activate CDK1 (in vitro and in vivo) to accelerate premature mitotic entry, leading to DNA damage and apoptosis.

Citation Format: Amriti Lulla, Tuyen D. Nguyen, Mi Li, Sofia Mastoraki, Yan Wang, Tuyen Bui, Marc Pina, Spiridon Tsavachidis, Gary Marshall, Kelly K. Hunt, Khandan Keyomarsi. Targeting PKMYT1 kinase is an effective treatment strategy in triple negative breast cancers with low molecular weight cyclin E (LMW-E) expression [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 950.

Local-Regional Recurrence After Neoadjuvant Endocrine Therapy: Data from ACOSOG Z1031 (Alliance), a Randomized Phase 2 Neoadjuvant Comparison Between Letrozole, Anastrozole, and Exemestane for Postmenopausal Women with Estrogen Receptor-Positive Clinical Stage 2 or 3 Breast Cancer

BACKGROUND

The ACOSOG Z1031 trial addressed the ability of three neoadjuvant aromatase inhibitors (NAIs) to reduce residual disease (cohort A) and to assess whether switching to neoadjuvant chemotherapy (NCT) after 4 weeks of receiving NAI with Ki67 greater than 10% increases pathologic complete response (pCR) in postmenopausal women with estrogen receptor-enriched (Allred score 6-8) breast cancer (BC).

METHODS

The study enrolled 622 women with clinical stage 2 or 3 estrogen receptor-positive (ER+) BC. Cohort A comprised 377 patients, and cohort B had 245 patients. The analysis cohort consisted of 509 patients after exclusion of patients who did not meet the trial eligibility criteria, switched to NCT or surgery due to 4-week Ki67 greater than 10%, or withdrew before surgery. Distribution of time to local-regional recurrence (LRR) was estimated using the competing-risk approach, in which distant recurrence and second primaries were considered to be competing-risk events. Patients who died without LRR, distant recurrence, or a second primary were censored at the last evaluation.

RESULTS

Of the 509 patients, 342 (67.2%) had breast-conserving surgery (BCS). Of 221 patients thought to require mastectomy at presentation, 50% were able to have BCS. Five (1%) patients had no residual disease in the breast or nodes at surgery. Among 382 women alive at this writing, 90% have been followed longer than 5 years. The 5-year cumulative incidence rate for LRR is estimated to be 1.53% (95% confidence interval 0.7-3.0%).

CONCLUSIONS

Rarely does NAI result in pCR for patients with stage 2 or 3 ER+ BC. However, a significant proportion will have downstaged to allow for BCS. Local-regional recurrence after surgery is uncommon (1.5% at 5 years), supporting the use of BCS after NAI.

Sequential Targeting of Retinoblastoma and DNA Synthesis Pathways Is a Therapeutic Strategy for Sarcomas That Can Be Monitored in Real Time

Treatment strategies with a strong scientific rationale based on specific biomarkers are needed to improve outcomes in patients with advanced sarcomas. Suppression of cell-cycle progression through reactivation of the tumor suppressor retinoblastoma (Rb) using CDK4/6 inhibitors is a potential avenue for novel targeted therapies in sarcomas that harbor intact Rb signaling. Here, we evaluated combination treatment strategies (sequential and concomitant) with the CDK4/6 inhibitor abemacicib to identify optimal combination strategies. Expression of Rb was examined in 1,043 sarcoma tumor specimens, and 50% were found to be Rb-positive. Using in vitro and in vivo models, an effective two-step sequential combination strategy was developed. Abemaciclib was used first to prime Rb-positive sarcoma cells to reversibly arrest in G1 phase. Upon drug removal, cells synchronously traversed to S phase, where a second treatment with S-phase targeted agents (gemcitabine or Wee1 kinase inhibitor) mediated a synergistic response by inducing DNA damage. The response to treatment could be noninvasively monitored using real-time positron emission tomography imaging and serum thymidine kinase activity. Collectively, these results show that a novel, sequential treatment strategy with a CDK4/6 inhibitor followed by a DNA-damaging agent was effective, resulting in synergistic tumor cell killing. This approach can be readily translated into a clinical trial with noninvasive functional imaging and serum biomarkers as indicators of response and cell cycling.

SIGNIFICANCE

An innovative sequential therapeutic strategy targeting Rb, followed by treatment with agents that perturb DNA synthesis pathways, results in synergistic killing of Rb-positive sarcomas that can be noninvasively monitored.

Prospective Study of Pain Outcomes Associated With Breast Surgery in Women With Nonhereditary Breast Cancer

OBJECTIVE

To assess pain severity and interference with life in women after different types of breast cancer surgery and the demographic, treatment-related, and psychosocial variables associated with these pain outcomes.

SUMMARY OF BACKGROUND DATA

Data are conflicting regarding pain outcomes and quality of life (QOL) among women who undergo different types of breast surgery.

METHODS

Women with nonhereditary breast cancer completed the brief pain inventory before surgery and at 1, 6, 12, and 18 months postsurgery. We assessed associations between pain outcomes and CPM status and mastectomy status using multivariable repeated measures models. We assessed associations between pain outcome and QOL and decision satisfaction.

RESULTS

Of 288 women (mean age 56 years, 58% non-Hispanic White), 50 had CPM, 75 had unilateral mastectomy, and 163 had BCS. Mean pain severity scores were higher at one (2.78 vs 1.9, P = 0.016) and 6 months (2.79 vs 1.96, P = 0.031) postsurgery in women who had CPM versus those who did not, but there was no difference at 12 and 18 months. Comparing mastectomy versus BCS, pain severity was higher at 1 and 12 months. There was a significant interaction between pain severity and time point for CPM ( P = 0.006), but not mastectomy status ( P = 0.069). Regardless of surgery type, Black women had higher pain severity ( P = 0.004) than White women. Higher pain interference was associated with lower QOL ( P < 0.001) and lower decision satisfaction ( P = 0.034).

CONCLUSIONS

Providers should counsel women considering mastectomy about the potential for greater acute pain and its impact on overall well-being. Racial/ethnic disparities in pain exist and influence pain management in breast surgical patients.

Abstract P6-01-06: Multi-Parametric MRI-Based Radiomics Models from Tumor and Peritumoral Regions as Potential Predictors of Treatment Response to Neoadjuvant Systemic Therapy in Triple Negative Breast Cancer Patients

PURPOSE Triple negative breast cancer (TNBC) is an aggressive and heterogeneous subtype of breast cancer. Pathologic complete response (pCR) to neoadjuvant systemic therapy (NAST) predicts better survival. Early prediction of the treatment response can potentially triage non-responding patients to alternative protocol treatments, spare them of the unneeded toxicity, and improve pCR. We evaluated the ability of radiomic textural analysis of intratumoral and peritumoral regions on the dynamic contrast enhanced (DCE) and diffusion-weighted imaging (DWI) MRI images obtained early during NAST to predict pCR. MATERIALS AND METHODS This IRB-approved prospective study (NCT02276443) included 182 patients with biopsy proven stage I-III TNBC who had multiparametric MRIs at baseline (BL), post 2 cycles (C2), and post 4 cycles (C4) of NAST before surgery. Tumors and peritumoral regions of 5 mm and 10 mm in thickness were segmented on the 2.5 minutes DCE subtraction images and on the b=800 DWI images. Ten histogram-based first order texture features including mean, minimum, maximum, standard deviation, kurtosis, skewness, 1st, 5th, 95th, and 99th percentile, and 300 radiomic Grey Level Co-occurrence matrix (GLCM) features along with their absolute and relative differences between the 3 imaging time points were extracted from the tumors and from the peritumoral regions with an in-house Matlab toolbox. Treatment response at surgery (pCR vs non-pCR) was documented. The samples were divided into training and testing datasets by a 2:1 ratio. Area under the receiver operating characteristics curve (AUC ROC) was calculated for univariate analysis in predicting pCR. Logistic regression with elastic net regularization was performed for texture feature selection. Parameter optimization was performed by using 5-fold cross-validation based on mean cross-validated AUC in the training set. RESULTS Of 182 TNBC patients, 88 (48%) had pCR and 94 (52%) did not achieve pCR. Eight multivariate models combining radiomic features from both DCE and DWI tumoral and peritumoral regions had AUC &gt; 0.8 (0.807-0.831) with p-value &lt; 0.001 in both training and testing sets. The highest AUC=0.831 was obtained from a model consisting of 15 radiomic features: tumor DWI (5 GLCM features) at C2, peritumoral region on DCE (skewness) at C2, tumor DCE (1st, 5th percentile) at C4, tumor DWI (3 GLCM features) at C4, peritumoral region DWI (1 GLCM feature) at C4, and the relative difference between C4/C2 on DCE (5th, 95th percentile and mean). CONCLUSION Multi-parametric MRI-based radiomics models from the tumor and the peritumoral regions showed high accuracy as potential early predictors of NAST response in TNBC patients.

Citation Format: Rania M. Mohamed, Bikash Panthi, Beatriz Adrada, Rosalind Candelaria, Mary S. Guirguis, Wei Yang, Medine Boge, Miral Patel, Nabil Elshafeey, Sanaz Pashapoor, Zijian Zhou, Jong Bum Son, Ken-Pin Hwang, H. T. Carisa Le-Petross, Jessica Leung, Marion E. Scoggins, Gary J. Whitman, Zhan Xu, Deanna L. Lane, Tanya Moseley, Frances Perez, Jason White, Elizabeth Ravenberg, Alyson Clayborn, Mark Pagel, Huiqin Chen, Jia Sun, Peng Wei, Alastair M. Thompson, Stacy Moulder, Anil Korkut, Lei Huo, Kelly K. Hunt, Jennifer K. Litton, Vicente Valero, Debu Tripathy, Clinton Yam, Jingfei Ma, Gaiane Rauch. Multi-Parametric MRI-Based Radiomics Models from Tumor and Peritumoral Regions as Potential Predictors of Treatment Response to Neoadjuvant Systemic Therapy in Triple Negative Breast Cancer Patients [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-06.

Abstract OT2-07-01: Feasibility study to evaluate performance of the LUM Imaging System for intraoperative detection of residual tumor in breast cancer patients receiving and not receiving neoadjuvant therapy

Background: Microscopically tumor-free lumpectomy margins are critical for safe breast conserving surgery. With current tools, 15%-25% of lumpectomies have positive margins that require second surgical procedures and increase cost and patient discomfort. Additionally, current lumpectomy margin assessment techniques show poor performance in predicting residual disease at re-excision, with a PPV of 35%. Better detection tools are needed to identify residual cancer during the initial lumpectomy and reduce second operations. LUM015 is a protease-activated fluorescent imaging agent that accumulates in tumor cells and tumor associated macrophages after preoperative intravenous injection. The LUM Imaging System visualizes activated LUM015 in the lumpectomy cavity via a hand-held wide field detector and proprietary tumor detection software. This system has been tested in multiple single-site studies and two prospective multi-site studies enrolling &gt;600 patients, and demonstrated successful detection of residual lumpectomy cavity tumor. Initial studies excluded the approximately 20% of patients receiving neoadjuvant therapy. Patchy tumor cell death with preoperative therapy can leave small, multifocal deposits of tumor invisible on pre-operative imaging and not palpable or visible during surgery. We now evaluate the LUM Imaging System in patients with and without neoadjuvant therapy. Trial Design and Specific Aims: This prospective, multi-center study at 6 US sites tests the LUM Imaging System in lumpectomy surgery after neoadjuvant therapy to evaluate potential impact of treatment-related tissue changes and tumor cell death on tumor detection algorithms. An initial cohort of 10 patients address the objective of algorithm development. A second cohort of 104 patients will further evaluate the feasibility of the LUM Imaging System after neoadjuvant therapy. A third cohort will enroll 208 patients who have not received neoadjuvant therapy. All cohorts are evaluated for safety and for reduction in residual tumor after LUM Imaging System guidance compared to standard of care lumpectomy. After excision of the main lumpectomy specimen, patients are randomized 3:1 to device or control arms. In the device arm, the cavity is imaged and margins with LUM015 signal are excised. Final comprehensive shaved margins are removed in both arms to evaluate extent of residual disease after the use of the LUM Imaging System or after standard lumpectomy. No LUM Imaging is performed in the control arm, however, all patients are injected with LUM015 to evaluate drug safety. Patient reported outcomes assessing re-excision concerns, breast appearance and preferences for treatment type are collected. Eligibility Criteria: This study seeks to enroll women 18 and older with histologically confirmed primary invasive breast cancer (IBC), ductal carcinoma in situ (DCIS) or a combination of IBC/DCIS undergoing a lumpectomy for their breast malignancy who have received any form of neoadjuvant treatment prior to surgery (cohorts 1 and 2) or who have not received any therapy prior to lumpectomy (cohort 3). Patients allergic to polyethylene glycol or intravenous contrast agents are excluded. Use of blue node mapping dyes before imaging with the LUM015 is not allowed per study protocol. Accrual and Study Progress: Cohort 1 has completed enrollment and interim analysis. No new risks specific to the neoadjuvant population were identified. LUM015 fluorescent signals measured in neoadjuvant patients were within the expected range, and no changes to the tumor detection algorithm were required. Cohorts 2 and 3 have enrolled a total of 38 patients. This trial is registered as NCT04440982. The NIH funds this study through a R01 grant issued to Massachusetts General Hospital.

Citation Format: Irene L. Wapnir, Kelly K. Hunt, E Shelley Hwang, Kate Smith, Peter Blumencranz, David Carr, Jorge Ferrer, Heidi Santa Cruz, Alexandra Webster, Julia Shanno, Alexander Pogrebinsky, Manna Chang, Barbara L. Smith. Feasibility study to evaluate performance of the LUM Imaging System for intraoperative detection of residual tumor in breast cancer patients receiving and not receiving neoadjuvant therapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-07-01.

Abstract P6-01-34: Longitudinal DCE-MRI Radiomic Models for Early Prediction of Response to Neoadjuvant Systemic Therapy (NAST) in Triple Negative Breast Cancer (TNBC) Patients

Background and Purpose Early prediction of neoadjuvant systemic therapy (NAST) response in triple negative breast cancer (TNBC) patients could potentially aid in the selection of alternative therapies and avoid unnecessary toxicity in patients unlikely to achieve pathologic complete response (pCR) with NAST. In this study, we investigated the radiomic features of the peritumoral and the tumoral regions from dynamic contrast enhanced (DCE) MRI acquired at different time points of NAST for early treatment response prediction in TNBC. Methods and Materials This study included 182 biopsy-confirmed stage I-III TNBC patients enrolled in an IRB approved prospective clinical trial (NCT02276433). All patients underwent DCE-MRI on a GE 3T MRI scanner at baseline (BL), after two (C2) and four (C4) cycles of doxorubicin/cyclophosphamide based chemotherapy and before surgery. The peritumoral and the tumoral regions were segmented manually by two fellowship-trained radiologists using early phase (2.5 min) DCE-MRI subtraction images. Ten first order radiomic features, 300 grey-level-co-occurrence matrix (GLCM) features along with their absolute and relative differences (C4/BL, C2/BL, C4/C2) between the 3 imaging time points were extracted from the peritumoral and the tumoral regions. Patients were randomly divided into training and testing sets in a 2:1 ratio. For univariate analysis, area under the receiver operating characteristics curve (AUC ROC) was measured to determine the features most predictive of pCR/non-pCR. Wilcoxon Rank Sum test was used to test the statistical significance of predictive performance. In multivariate analysis, radiomic models were established using logistic regression with elastic net regularization followed by 5-fold cross validation for performance assessment. Results Eighty-eight (48%) patients had pCR (59 training, 29 testing) and 94 (52%) patients had non-pCR (63 training, 31 testing). Twenty-five radiomic features (4 from peritumoral C4, 5 from tumoral C4, 4 from peritumoral C4/BL, 6 from tumoral C4/BL, 2 from peritumoral C4/C2 and 4 from tumoral C4/C2) were statistically significant with AUC ≥ 0.75 in both the training and the testing sets at the univariate analysis. The significant features at C4 had AUCs of 0.75-0.79 for the training set and 0.76-0.81 for the testing set. Changes measured between C4 and BL or C2 showed AUC of 0.76-0.84 in the training and 0.75-0.81 in the testing datasets. Eleven multivariate regression models comprised of radiomic features at BL, C2, C4 and their changes (C4/BL, C4/C2 and C2/BL) showed an AUC of 0.80-0.84 for cross validation and an AUC of 0.80-0.82 for independent testing. Conclusions Radiomic models using longitudinal DCE MRI parameters of peritumoral and tumoral regions during NAST have the potential to predict pCR in TNBC patients undergoing NAST.

Citation Format: Bikash Panthi, Rania M. Mohamed, Beatriz Adrada, Rosalind Candelaria, Mary S. Guirguis, Wei Yang, Medine Boge, Miral Patel, Nabil Elshafeey, Sanaz Pashapoor, Zijian Zhou, Jong Bum Son, Ken-Pin Hwang, H. T. Carisa Le-Petross, Jessica Leung, Marion E. Scoggins, Gary J. Whitman, Zhan Xu, Deanna L. Lane, Tanya Moseley, Frances Perez, Jason White, Elizabeth Ravenberg, Alyson Clayborn, Mark Pagel, Huiqin Chen, Jia Sun, Peng Wei, Alastair M. Thompson, Stacy Moulder, Anil Korkut, Lei Huo, Kelly K. Hunt, Jennifer K. Litton, Vicente Valero, Debu Tripathy, Clinton Yam, Jingfei Ma, Gaiane Rauch. Longitudinal DCE-MRI Radiomic Models for Early Prediction of Response to Neoadjuvant Systemic Therapy (NAST) in Triple Negative Breast Cancer (TNBC) Patients [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-34.

Abstract HER2-01: HER2-01 Clinical and Molecular Characteristics of HER2-low/zero Early Stage Triple-Negative Breast Cancer

Background: In the metastatic setting, low HER2 expression is associated with clinical benefit from trastuzumab deruxtecan, a HER2-targeting antibody drug conjugates. However, little is known about the biological significance of low HER2 expression in patients with early stage triple-negative breast cancer (TNBC) receiving neoadjuvant therapy (NAT). Methods: Out of 595 patients with stage I-III TNBC enrolled on the prospective ARTEMIS trial (NCT02276443) from 2015-2021, we identified 367 patients with available HER2 immunohistochemistry (IHC) results on pre-NAT tumor tissue (HER2-zero: n=218; HER2-low [IHC 1+, 2+]: n=149). All patients were treated with anthracycline-based NAT. In cases where sufficient pre-NAT tumor tissue were available, additional IHC and/or RNAseq were performed. Differential gene expression (DGE) and pathway analysis were performed using DEseq2. Gene set enrichment analysis (GSEA) was performed using the Hallmark gene sets. Deconvolution analyses were performed using CIBERSORT. We controlled for multiple hypothesis using a false discovery rate (FDR) threshold with the Benjamini-Hochberg method, accepting as significant genes with at least a 2-fold change and &lt; 5% FDR. Results: Table 1 summarizes baseline clinicopathological features of the 367 patients. Compared to HER2-zero tumors, HER2-low tumors were less likely of metaplastic histology (p=0.001), associated with lower Ki67 (p=0.017) and were more likely to be androgen receptor (AR)-positive (p=0.01). There were no significant differences in tumor-infiltrating lymphocytes (TILs) infiltration and PD-L1 expression between HER2-zero and HER2-low tumors. Among the 226 patients with sufficient pre-NAT tissue for RNAseq, DGE analyses demonstrated upregulation of genes involved in fatty acid metabolism (ACSM1) and steroid hormone metabolism (DHRS2, UGT2B28) in HER2-low tumors compared with HER2-zero tumors. Deconvolution analyses revealed no significant differences between predicted proportions of immune cell subpopulations between HER2-low and HER2-zero tumors. Although rates of pCR were not significantly different between patients with HER2-zero (46%) and HER2-low tumors (40%) (p=0.34), non-pCR in patients with HER2-low tumors was associated with increased expression of EREG, which encodes an EGFR ligand, while non-pCR in patients with HER2-zero tumors was associated with downregulation in genes involved in immune response pathways. GSEA further identified the Hallmark allograft rejection (FDR q=0.001), interferon gamma response (FDR q=0.002), and interferon alpha response pathways (FDR q=0.007) as the 3 most significantly downregulated pathways in HER2-zero tumors from patients experiencing a non-pCR relative to HER2-zero tumors from patients experiencing a pCR. Conclusion: In early stage TNBC, low HER2 expression is associated with increased AR expression and upregulation of genes associated with fatty acid and steroid hormone metabolism. Gene expression analyses suggest that drivers of resistance to NAT differ between HER2-low and HER2-zero tumors. Biological differences between HER2-zero and HER2-low tumors exist and may influence future personalized treatment for patients with early stage TNBC.

Citation Format: Clinton Yam, Ziyi Li, Anil Korkut, Wencai Ma, Elisabeth Kong, Holly A. Hill, Hussein Abbas, Sausan Abouharb, Beatriz Adrada, Banu K. Arun, Carlos H. Barcenas, Ajit Bisen, Daniel Booser, Aman Buzdar, Rosalind Candelaria, Junjie Chen, Alyson Clayborn, Senthil Damodaran, Qingqing Ding, Haven Garber, Gabriel N. Hortobagyi, Kelly K. Hunt, Nuhad K. Ibrahim, Adaeze Iheme, Meghan S. Karuturi, Kimberly Koenig, Rachel M. Layman, Jangsoon Lee, Jennifer K. Litton, Melissa Mitchell, Giancarlo Moscol, Jason Mouabbi, Rashmi K. Murthy, Oluchi Oke, Paula Pohlmann, David Ramirez, Elizabeth Ravenberg, Sadia Saleem, Mediget Teshome, Vicente Valero, Jason White, Madison Williams, Wendy Woodward, Chasity Yajima, Naoto T. Ueno, Ken Chen, Gaiane Rauch, Lei Huo, Debu Tripathy. HER2-01 Clinical and Molecular Characteristics of HER2-low/zero Early Stage Triple-Negative Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr HER2-01.

Abstract P6-10-06: A preoperative window-of-opportunity study of imlunestrant in estrogen receptor-positive, HER2-negative early breast cancer: Results from the EMBER-2 study

Background: Imlunestrant is a novel, orally bioavailable selective estrogen receptor degrader (SERD) with pure antagonistic properties that result in sustained inhibition of estrogen receptor (ER)-dependent gene transcription and cell growth. In a phase 1 study, imlunestrant monotherapy showed favourable safety, pharmacokinetics (PK) and preliminary efficacy in heavily pre-treated ER-positive (ER+) advanced breast cancer patients (Jhaveri ASCO 2022). Here, we present pharmacodynamic (PD) data from the preoperative window of opportunity (WOO) study (EMBER-2, NCT04647487), evaluating the biological activity of imlunestrant monotherapy in ER+, HER2-negative (HER2-) early breast cancer (EBC).

Methods: Post-menopausal women with stage I–III operable ER+ (&gt;50%) or Allred score &gt;5, HER2- untreated EBC ≥1 cm in diameter were randomized 1:1 to imlunestrant 400 mg once daily (QD) or imlunestrant 800 mg QD for 15 days (treatment window of -2 to +7 days) up to the surgery date. Pre- and on-treatment tumor samples were compared for changes in PD biomarkers. Primary study objective was change in ER expression (measured by IHC and quantified by H-score). Secondary objectives were change in progesterone receptor (PR) expression (measured by IHC and quantified by H-score) and Ki-67 (measured by IHC and expressed by percentage positive scoring) along with evaluation of safety and tolerability.

Results: From Apr 28, 2021, to Mar 11, 2022, 58 patients were enrolled of which 54 were biomarker-evaluable for ER expression (400 mg: n = 28; 800 mg: n = 26). Patient demographics and tumor characteristics for all enrolled patients were similar across cohorts, with a median age of 64 years (50-83), 72% invasive ductal carcinoma (IDC), 28% invasive lobular carcinoma (ILC), 59% stage I, 36% stage II and 5% stage III disease. 91% of the patients had a compliance rate higher than 80%. Among biomarker evaluable patients, relative reduction in PD biomarkers after a median of 15 days (range 13 to 23 days) of treatment are presented in Table 1. There was no significant difference in PD biomarker modulation noted between the two imlunestrant doses (400 mg vs 800 mg) or based on tumor histology (IDC, ILC). Imlunestrant was well tolerated. There were no discontinuations due to adverse events (AEs). Treatment-related AEs (TRAEs) were mainly grade 1, most commonly: fatigue (10%), diarrhea (9%), hot flushes (7%), and nausea (5%). There were no TRAEs of diarrhea and nausea observed at the 400 mg dose. No grade 3 or higher TRAEs were reported.

Conclusion: Imlunestrant demonstrated evidence of target engagement along with consistent biological activity across all evaluated dose levels and was well tolerated in an EBC population, further supporting continued adjuvant development in the ongoing EMBER-4 study. Additional biomarker analyses for the EMBER-2 study are also planned.

Table 1. Relative reduction in PD biomarkers from Baseline to Day 15

Citation Format: Patrick Neven, Nicole Stahl, Maria Vidal, Miguel Martín, Nadia Harbeck, Peter A. Kaufman, Francois-Clement Bidard, Peter A. Fasching, Philippe Aftimos, Erika Hamilton, Stacey Carter, Peter Schmid, Duncan Wheatley, Manali Bhave, Kelly K. Hunt, Swati A. Kulkarni, Roohi Ismail-Khan, Claudia Karacsonyi, Shawn T. Estrem, Umut Ozbek, Bastien Nguyen, Eva Ciruelos. A preoperative window-of-opportunity study of imlunestrant in estrogen receptor-positive, HER2-negative early breast cancer: Results from the EMBER-2 study. [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-10-06.

Other Primary Malignancies in Patients with Breast Cancer Who Undergo Germline Panel Testing

BACKGROUND

Women with a history of breast cancer (BC) more commonly have a diagnosis of other primary malignancies (OPMs) than the general population. This study sought to evaluate OPMs among patients with BC who underwent germline testing with a hereditary BC gene panel.

METHODS

The study identified women 18 years of age or older with a history of unilateral BC who underwent multi-gene panel testing between January 2014 and August 2019 at the authors' institution. Patient, tumor, and treatment factors for BC and OPM diagnoses were collected for descriptive, univariate, and overall survival (OS) analyses.

RESULTS

Among 1163 patients, 330 (28.4%) had an OPM. The median follow-up period was 4.1 years from BC diagnosis. Of the 1163 patients, 209 (18%) had a BRCA pathogenic variant (PV), 306 (26.4%) had a non-BRCA PV, and 648 (55.7%) had no PV. Development of an OPM varied according to germline testing result, with an OPM developing for 18.6% (39/209) of the patients with a BRCA PV, 31.8% (204/648) of the patients with no PV, and 28.4% (87/306) of the patients with a non-BRCA PV (p < 0.0001). The most common OPMs were ovarian (n = 60), uterine (n = 44), sarcoma (n = 36), melanoma (n = 27), colorectal (n = 22), and lymphoma (n = 20) malignancies. The 5-year OS was 96%. The patients with an OPM 5 years after BC diagnosis had a shorter OS than those who did not (93.4% vs 97.5%; p = 0.002).

CONCLUSION

More than 25% of women with BC who underwent germline panel testing had an OPM diagnosed during the short-term follow-up period, and the diagnosis of an OPM was associated with reduced OS. These data have implications for counseling BC patients who undergo germline testing regarding future cancer screening.

Abstract P1-05-15: DCE-MRI for early prediction of excellent response versus chemoresistance in triple negative breast cancer

PURPOSE Triple-negative breast cancer (TNBC) is a heterogeneous disease with variable response to neoadjuvant therapy (NAT). Pathologic complete response (pCR) has become a prognostic marker for overall and disease-free survival. The aim of this study was to determine if dynamic contrast-enhanced (DCE)-MRI after 2 and/or 4 cycles of NAT can identify patients with a high likelihood of achieving pCR, triaging them to standard of care (SOC), or, when appropriate, to de-escalation trials. Conversely, we aimed to identify chemoresistant tumors that are unlikely to achieve pCR and may benefit from escalated targeted trials.

METHOD AND MATERIALS 309 patients with stage I-III TNBC underwent DCE-MRI (temporal resolution: 9-12 sec) at baseline (BL), 2 cycles (C2), and 4 cycles (C4) of SOC doxorubicin/cyclophosphamide (AC) NAT as part of a prospective IRB-approved study (NCT02276443). Tumor volumes of the index lesion were calculated using 3 axis measurements during the early phase of the DCE-MRI (60s). Percent tumor volume reduction (TVR) between BL, C2, and C4 was calculated. Patients were randomly assigned to a training or a validation cohort in a 1:1 ratio. pCR was assessed at surgery after completion of SOC NAT. Correlation between pCR and TVR was evaluated using ROC analysis.

RESULTS Of 309 TNBC patients, 136 (44%) achieved pCR. Following 2 cycles of NAT, TVR &gt;80% was predictive of pCR (chemosensitivity), while TVR ≤ 55% was predictive of non-pCR (chemoresistance) with PPV 80%, NPV 89%, AUC 0.811 (0.73~0.893, p&lt; 0.0001) in the training cohort, and PPV 82%, NPV 85%, AUC 0.815 (CI:0.736~0.894, p&lt; 0.0001) in the validation cohort. Following 4 cycles of NAT, TVR &gt;90% was predictive of pCR, while TVR ≤80% was predictive of non-pCR with PPV 80%, NPV 84%, AUC 0.827 (0.756~0.898, p&lt; 0.0001) in the training cohort and with PPV 73%, NPV 82%, AUC 0.785 (CI:0.709~0.862, p&lt; 0.001) in the validation cohort. Using this model, the pCR status was correctly classified in 50% of TNBC patients using C2 DCE-MRI in the training cohort, and 54% in the validation cohort. Only 8% were misclassified in the training cohort, and 10% in the validation cohort. Using C4 DCE-MRI, the pCR status of 61% and 57% of TNBC was correctly classified in the validation and the testing cohorts, respectively. 12% were misclassified in the validation cohort, and 21% in the testing cohort.

CONCLUSION DCE-MRI after 2 and 4 cycles of AC-based NAT correctly predicted the pCR status of 54% and 57% of TNBC patients, respectively, as either excellent responders or nonresponders with high AUC 0.811 and 0.827. This may allow patients to be triaged to SOC NAT with option of de-escalation or early targeted therapies for non-responders.

Clinical Impact of External Beam Radiotherapy for Surgically Resected Primary Retroperitoneal Liposarcoma

INTRODUCTION

EORTC-62092 (STRASS) was a phase 3, randomized study that compared surgery alone versus surgery plus neoadjuvant radiotherapy (RT) for retroperitoneal sarcomas. RT was not associated with improved abdominal recurrence-free survival, the primary outcome measure, although on subanalysis, there may have been benefit for well-differentiated (WD) liposarcoma. This study investigated the real-world use and outcomes of RT (neoadjuvant and adjuvant) for the management of retroperitoneal liposarcoma.

METHODS

We queried the National Cancer Database (NCDB) (2004-2017) for patients with nonmetastatic, primary retroperitoneal liposarcoma treated with resection with or without RT (n = 3911). Patients were stratified by treatment type and histology [WD (n = 2252), dedifferentiated (DD) (n = 1659)]. Propensity score (PS) matching was used before comparison of treatment groups. Overall survival (OS) was the primary outcome measure.

RESULTS

Median follow-up time was 4.1 years, and median OS was 10.7 years. There was no association between RT and OS for either WDLPS or DDLPS cohorts. We performed a subgroup analysis of neoadjuvant RT only, similar to STRASS. For WDLPS after PS matching (n = 208), neoadjuvant RT was not associated with OS (hazard ratio [HR] 1.01, p = 0.0523) but was associated with longer postoperative hospital stay (p = 0.012). For DDLPS after PS matching (n = 290), neoadjuvant RT was not associated with OS (HR 1.02, p = 0.889). For both WD-LPS and DD-LPS, utilization of neoadjuvant RT was associated with treatment at high-volume (≥ 10 cases/year) and academic/network facilities.

CONCLUSIONS

For primary retroperitoneal liposarcoma treated with surgical resection, radiotherapy was not associated with an overall survival benefit in this propensity-matched, adjusted analysis of the NCDB.

Practice Pattern Variability in the Management of Regional Lymph Node Metastasis in Extremity and Trunk Soft Tissue Sarcoma: A Survey of the Society of Surgical Oncology and Musculoskeletal Tumor Society Membership

BACKGROUND

Regional lymph node metastasis in extremity and trunk soft tissue sarcoma (ETSTS) is rare with no standardized management. We sought to determine management patterns for regional lymph node metastasis in ETSTS.

METHODS

A survey regarding the management of ETSTS lymph node metastasis was distributed to the membership of the Musculoskeletal Tumor Society (MSTS) and the Society of Surgical Oncology (SSO) in January 2022. The survey queried the type of training (surgical oncology, orthopedic oncology), details of their practice setting, and management decisions of hypothetical ETSTS scenarios that involved potential or confirmed lymph node metastasis.

RESULTS

The survey was distributed to 349 MSTS members (open rate of 63%, completion rate 21%) and 3026 SSO members (open rate of 55%, completion rate 4.7%) and was completed by 214 respondents, of whom 73 (34.1%) and 141 (65.9%) were orthopedic oncology and surgical oncology fellowship-trained, respectively. The majority of respondents practiced in an academic setting (n = 171, 79.9%) and treat >10 extremity sarcoma cases annually (n = 138, 62.2%). In scenarios with confirmed nodal disease for clear cell and epithelioid sarcoma, surgical oncologists were inclined to perform lymphadenectomy, while orthopedic oncologists were inclined to offer targeted lymph node excision with adjuvant radiation (p < 0.001). There was heterogeneity of responses regarding the management of nodal disease regardless of training background.

CONCLUSION

Self-reported management of nodal disease in ETSTS was variable among respondent groups with differences and similarities based on training background. These data highlight the variability of practice for nodal disease management and the need for consensus-based guidelines.

Re-excision After Unplanned Excision of Soft Tissue Sarcoma is Associated with High Morbidity and Limited Pathologic Identification of Residual Disease

BACKGROUND

Patients with unplanned excision (UPE) of trunk and extremity soft tissue sarcoma (STS) present a significant management challenge for sarcoma specialists. Oncologic re-resection has been considered standard practice after UPE with positive or uncertain margins. A strategy of active surveillance or "watch and wait" has been suggested as a safe alternative to routine re-excision. In this context, the current study sought to evaluate short-term outcomes and morbidity after re-resection to better understand the risks and benefits of this treatment strategy.

METHODS

A retrospective, single-institution study reviewed patients undergoing oncologic re-resection after UPE of an STS during a 5-year period (2015-2020), excluding those with evidence of gross residual disease. Short-term clinical outcomes were evaluated together with final pathologic findings.

RESULTS

The review identified 67 patients undergoing re-resection after UPE of an STS. Of these 67 patients, 45 (67%) were treated with a combination of external beam radiation therapy (EBRT) and surgery. Plastic surgery was involved for reconstruction in 49 cases (73%). The rate of wound complications after re-resection was 45 % (n = 30), with 15 % (n = 10) of the patients experiencing a major wound complication. Radiation therapy and plastic surgery involvement were independently associated with wound complications. Notably, 45 patients (67%) had no evidence of residual disease in the re-resection specimen, whereas 13 patients (19 %) had microscopic disease, and 9 patients (13%) had indeterminate pathology.

CONCLUSION

Given the morbidity of re-resection and limited identification of residual disease, treatment plans and discussions with patients should outline the expected pathologic findings and morbidity of surgery.

Hypofractionated, 3-week, preoperative radiotherapy for patients with soft tissue sarcomas (HYPORT-STS): a single-centre, open-label, single-arm, phase 2 trial

BACKGROUND

The standard preoperative radiotherapy regimen of 50 Gy delivered in 25 fractions for 5 weeks for soft tissue sarcomas results in excellent local control, with major wound complications occurring in approximately 35% of patients. We aimed to investigate the safety of a moderately hypofractionated, shorter regimen of radiotherapy, which could be more convenient for patients.

METHODS

This single-centre, open-label, single-arm, phase 2 trial (HYPORT-STS) was done at a single tertiary cancer care centre (MD Anderson Cancer Center, Houston, TX, USA). We administered preoperative radiotherapy to a dose of 42·75 Gy in 15 fractions of 2·85 Gy/day for 3 weeks (five fractions per week) to adults (aged ≥18 years) with non-metastatic soft tissue sarcomas of the extremities or superficial trunk and an Eastern Cooperative Oncology Group performance status of 0-3. The primary endpoint was a major wound complication occurring within 120 days of surgery. Major wound complications were defined as those requiring a secondary operation, or operations, under general or regional anaesthesia for wound treatment; readmission to the hospital for wound care; invasive procedures for wound care; deep wound packing to an area of wound measuring at least 2 cm in length; prolonged dressing changes; repeat surgery for revision of a split thickness skin graft; or wet dressings for longer than 4 weeks. We analysed our primary outcome and safety in all patients who enrolled. We monitored safety using a Bayesian, one-arm, time-to-event stopping rule simulator comparing the rate of major wound complications at 120 days post-surgery among study participants with the historical rate of 35%. This trial is registered with ClinicalTrials.gov, NCT03819985, recruitment is complete, and follow-up continues.

FINDINGS

Between Dec 18, 2018, and Jan 6, 2021, we assessed 157 patients for eligibility, of whom 120 were enrolled and received hypofractionated preoperative radiotherapy. At no time did the stopping rule computation indicate that the trial should be stopped early for lack of safety. Median postoperative follow-up was 24 months (IQR 17-30). Of 120 patients, 37 (31%, 95% CI 24-40) developed a major wound complication at a median time of 37 days (IQR 25-59) after surgery. No patient had acute radiation toxicity (during radiotherapy or within 4 weeks of the radiotherapy end date) of grade 3 or worse (Common Terminology Criteria for Adverse Events [CTCAE] version 4.0) or an on-treatment serious adverse event. Four (3%) of 115 patients had late radiation toxicity (≥6 months post-surgery) of at least grade 3 (CTCAE or Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer Late Radiation Morbidity Scoring Scheme): femur fractures (n=2), lymphoedema (n=1), and skin ulceration (n=1). There were no treatment-related deaths.

INTERPRETATION

Moderately hypofractionated preoperative radiotherapy delivered to patients with soft tissue sarcomas was safe and could therefore be a more convenient alternative to conventionally fractionated radiotherapy. Patients can be counselled about these results and potentially offered this regimen, particularly if it facilitates care at a sarcoma specialty centre. Results on long-term oncological, late toxicity, and functional outcomes are awaited.

FUNDING

The National Cancer Institute.

Sentinel Lymph Node Biopsy and Formal Lymphadenectomy for Soft Tissue Sarcoma: A Single Center Experience of 86 Consecutive Cases

BACKGROUND

Lymph node metastases (LNMs) are rare in patients with soft tissue sarcoma (STS), and there is limited evidence to guide clinical management. We describe our experience with sentinel lymph node biopsy (SLNB) and lymphadenectomy in STS patients.

METHODS

A single-center, retrospective review was performed for patients with STS treated with SLNB and/or lymphadenectomy from 1994 to 2018. Clinicopathologic characteristics, multimodality treatment, regional/distant recurrence-free survival (RFS), and overall survival (OS) were examined.

RESULTS

Eighty-six patients underwent SLNB (n = 34) and/or lymphadenectomy (n = 60) for STS. The most frequent histologic subtypes were epithelioid, clear cell, and undifferentiated pleomorphic sarcoma. Eight of 34 (23.5%) patients had a positive SLNB with 5-year OS of 71.4% compared with 71.9% for those with a negative SLNB. Eight of the 26 SLN-negative patients (30.8%) eventually developed nodal recurrence (n = 2) and/or (n = 6) distant metastasis with an estimated 5-year OS of 50%. Of patients undergoing lymphadenectomy, estimated 5-year OS was 44.6% and median RFS was 12 months. Eight (13.3%) had distant disease at time of lymphadenectomy, 20 (33.3%) developed distant recurrence after lymphadenectomy, and 6 (10%) developed regional-only recurrence. Patients with regional-only recurrence after lymphadenectomy had an estimated 5-year OS of 66.7% compared with 29.1% for those who recurred distantly.

CONCLUSIONS

Patients with positive SLNB had similar survival to those with negative SLNB. Lymphadenectomy for isolated nodal disease is associated with poor RFS but reasonable 5-year OS when recurrence is regional-only. In STS, regional disease appears clinically distinct from distant metastatic disease and has better outcomes.

Abstract PR002: Antigen presentation and processing pathway is associated with early relapse after neoadjuvant immune checkpoint blockade (ICB) in dedifferentiated liposarcomas (DDLPS)

Background: We evaluated the activity of neoadjuvant ICB in localized resectable DDLPS (n=17) and undifferentiated pleomorphic sarcomas (UPS; n=10). DDLPS and UPS patients were randomized to neoadjuvant nivolumab or ipilimumab+nivolumab, with UPS patients receiving concurrent radiotherapy. We assessed genomic markers of early relapse (progression before surgery or relapse within 52 weeks following surgery) using longitudinally acquired tumor samples. Methods: RNA sequencing (RNAseq) and whole genome sequencing (WGS) were performed on longitudinally acquired samples (baseline biopsies and surgical specimens). Differential gene expression between any two groups of patients (i.e., non-early relapse [non-relapsers] vs early relapse [relapsers]) were selected (fold change&gt;1.5 and p value&lt;0.05). Gene set enrichment analyses (GSEA) of KEGG pathways were performed and a network-based approach used to identify genes/pathways associated with MHC-I. Results: At a median follow-up of 23 months, 12 patients (9 DDLPS, 3 UPS) relapsed, including 7 early relapses (relapsers: 5 DDLPS, 2 UPS). The median relapse-free survival was 22 months in DDLPS patients (6 months in relapsers; not reached [NR] in non-relapsers) and NR in UPS patients. At baseline, the most differentially upregulated pathways in non-relapsers compared to relapsers were “graft versus host disease” (GSEA Normalized Enrichment Score[NES]=2.25; False Discovery Rate[FDR] q= 0.009), “natural killer cell mediated cytotoxicity” (NES=2.17; FDR q=0.009), “antigen processing and presentation” (NES=2.16; FDR q=0.009), “allograft rejection” (NES=1.99; FDR q=0.019) and “B-cell receptor signaling pathway” (NES=1.87; FDR q=0.018). In DDLPS patients, the antigen presentation and processing pathway was the most upregulated pathway in non-relapsers compared to relapsers (NES=2.01; FDR q=0.025) while it was not significantly upregulated in UPS (NES=1.15; FDR q=0.62). When looking at pathways longitudinally, the antigen presentation and processing pathway was significantly upregulated at surgery compared to baseline in DDLPS. As antigen presentation and processing was significantly upregulated in DDLPS patients and associated with relapse, we looked for expressed neoantigens that may be processed and presented. Using WGS, we detected 5712 rearrangements at baseline in DDLPS, of which 230 were found in more than one tumor specimen. We also sought to identify genes associated with MHC-I. We selected genes upregulated during ICB comparing baseline to surgical specimens in DDLPS relapsers and looked at the top 10% of genes associated with MHC-I in order to identify potential therapeutic targets for combination. We identified 41 genes upregulated during ICB and associated with MHC-I in relapsers, for which up to 275 inhibitory compounds were found in drug databases. Conclusion: Antigen presentation and processing is a major driver of response to immunotherapy. Future efforts should focus on identifying which antigens are presented to find synergizing compounds in order to increase the clinical benefit of ICB.

Citation Format: Elise F. Nassif, Chia-Chin Wu, Kadir Akdemir, Russell G. Witt, Raymond Traweek, Brandon Cope, Prapassorn Thirasastr, Taylor Tate, Grace Mathew, Shadarra Crosby, Randy Chu, Mohammad Mohammad, Kenna Shaw, Ingram Davis, Khalida Wani, Alexander J. Lazar, Wei-Lien Wang, Sheila Duncan, Ashleigh B. Guadagnolo, Andrew J. Bishop, Valerae Lewis, Justin E. Bird, Keila E. Torres, Kelly K. Hunt, Barry W. Feig, Christopher P. Scally, Ravin Ratan, Shreyaskumar Patel, Robert S. Benjamin, Robert Satcher, Kevin McBride, Wolf H. Fridman, Ignacio Wistuba, Andrew Futreal, Jennifer A. Wargo, Neeta Somaiah, Christina L. Roland, Emily Z. Keung. Antigen presentation and processing pathway is associated with early relapse after neoadjuvant immune checkpoint blockade (ICB) in dedifferentiated liposarcomas (DDLPS) [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr PR002.