Predictors of Response to CDK4/6i Retrial After Prior CDK4/6i Failure in ER+ Metastatic Breast Cancer

After disease progression on endocrine therapy (ET) plus a CDK4/6 inhibitor, there is no standardized sequence for subsequent treatment lines for estrogen receptor positive (ER+) metastatic breast cancer (MBC). CDK4/6i retrial as a treatment strategy is commonplace in modern clinical practice; however, the available prospective data investigating this strategy have had inconclusive results. To frame this data in a real-world context, we performed a retrospective analysis assessing the efficacy of CDK4/6is in 195 patients who had previous exposure to CDK4/6i in a prior treatment line at our institution. Among patients who had stopped a CDK4/6i due to toxicity, CDK4/6i retrial either immediately after with a different CDK4/6i or in a further treatment line with the same initial CDK4/6i was both safe and effective, with a median time to treatment failure (TTF) of 10.1 months (95%CI, 4.8-16.9). For patients whose disease progressed on a prior CDK4/6i, we demonstrated comparable median TTFs for patients rechallenged with the same CDK4/6i (4.3 months, 95%CI 3.2-5.5) and with a different CDK4/6i (4.7 months, 95%CI 3.7-6.0) when compared to the recent PACE, PALMIRA, and MAINTAIN trials. Exploratory genomic analysis suggested that the presence of mutations known to confer CDK4/6i resistance, such as TP53 mutations, CDK4 amplifications, and RB1 or FAT1 loss of function mutations may be molecular biomarkers predictive of CDK4/6i retrial failure.

Redox signalling regulates breast cancer metastasis via phenotypic and metabolic reprogramming due to p63 activation by HIF1α

BACKGROUND

Redox signaling caused by knockdown (KD) of Glutathione Peroxidase 2 (GPx2) in the PyMT mammary tumour model promotes metastasis via phenotypic and metabolic reprogramming. However, the tumour cell subpopulations and transcriptional regulators governing these processes remained unknown.

METHODS

We used single-cell transcriptomics to decipher the tumour cell subpopulations stimulated by GPx2 KD in the PyMT mammary tumour and paired pulmonary metastases. We analyzed the EMT spectrum across the various tumour cell clusters using pseudotime trajectory analysis and elucidated the transcriptional and metabolic regulation of the hybrid EMT state.

RESULTS

Integration of single-cell transcriptomics between the PyMT/GPx2 KD primary tumour and paired lung metastases unraveled a basal/mesenchymal-like cluster and several luminal-like clusters spanning an EMT spectrum. Interestingly, the luminal clusters at the primary tumour gained mesenchymal gene expression, resulting in epithelial/mesenchymal subpopulations fueled by oxidative phosphorylation (OXPHOS) and glycolysis. By contrast, at distant metastasis, the basal/mesenchymal-like cluster gained luminal and mesenchymal gene expression, resulting in a hybrid subpopulation using OXPHOS, supporting adaptive plasticity. Furthermore, p63 was dramatically upregulated in all hybrid clusters, implying a role in regulating partial EMT and MET at primary and distant sites, respectively. Importantly, these effects were reversed by HIF1α loss or GPx2 gain of function, resulting in metastasis suppression.

CONCLUSIONS

Collectively, these results underscored a dramatic effect of redox signaling on p63 activation by HIF1α, underlying phenotypic and metabolic plasticity leading to mammary tumour metastasis.

Functional transcriptional signatures for tumor-type-agnostic phenotype prediction

Cancer transcriptional patterns exhibit both shared and unique features across diverse cancer types, but whether these patterns are sufficient to characterize the full breadth of tumor phenotype heterogeneity remains an open question. We hypothesized that cancer transcriptional diversity mirrors patterns in normal tissues optimized for distinct functional tasks. Starting with normal tissue transcriptomic profiles, we use non-negative matrix factorization to derive six distinct transcriptomic phenotypes, called archetypes, which combine to describe both normal tissue patterns and variations across a broad spectrum of malignancies. We show that differential enrichment of these signatures correlates with key tumor characteristics, including overall patient survival and drug sensitivity, independent of clinically actionable DNA alterations. Additionally, we show that in HR+/HER2- breast cancers, metastatic tumors adopt transcriptomic signatures consistent with the invaded tissue. Broadly, our findings suggest that cancer often arrogates normal tissue transcriptomic characteristics as a component of both malignant progression and drug response. This quantitative framework provides a strategy for connecting the diversity of cancer phenotypes and could potentially help manage individual patients.

Wasserstein HOG: Local Directionality Extraction via Optimal Transport

Directionally sensitive radiomic features including the histogram of oriented gradient (HOG) have been shown to provide objective and quantitative measures for predicting disease outcomes in multiple cancers. However, radiomic features are sensitive to imaging variabilities including acquisition differences, imaging artifacts and noise, making them impractical for using in the clinic to inform patient care. We treat the problem of extracting robust local directionality features by mapping via optimal transport a given local image patch to an iso-intense patch of its mean. We decompose the transport map into sub-work costs each transporting in different directions. To test our approach, we evaluated the ability of the proposed approach to quantify tumor heterogeneity from magnetic resonance imaging (MRI) scans of brain glioblastoma multiforme, computed tomography (CT) scans of head and neck squamous cell carcinoma as well as longitudinal CT scans in lung cancer patients treated with immunotherapy. By considering the entropy difference of the extracted local directionality within tumor regions, we found that patients with higher entropy in their images, had significantly worse overall survival for all three datasets, which indicates that tumors that have images exhibiting flows in many directions may be more malignant. This may seem to reflect high tumor histologic grade or disorganization. Furthermore, by comparing the changes in entropy longitudinally using two imaging time points, we found patients with reduction in entropy from baseline CT are associated with longer overall survival (hazard ratio = 1.95, 95% confidence interval of 1.4-2.8, p = 1.65e-5). The proposed method provides a robust, training free approach to quantify the local directionality contained in images.

Preoperative immune checkpoint inhibition and cryoablation in early-stage breast cancer

Local cryoablation can engender systemic immune activation/anticancer responses in tumors otherwise resistant to immune checkpoint blockade (ICB). We evaluated the safety/tolerability of preoperative cryoablation plus ipilimumab and nivolumab in 5 early-stage/resectable breast cancers. The primary endpoint was met when all 5 patients underwent standard-of-care primary breast surgery undelayedly. Three patients developed transient hyperthyroidism; one developed grade 4 liver toxicity (resolved with supportive management). We compared this strategy with cryoablation and/or ipilimumab. Dual ICB plus cryoablation induced higher expression of T cell activation markers and serum Th1 cytokines and reduced immunosuppressive serum CD4+PD-1hi T cells, improving effector-to-suppressor T cell ratio. After dual ICB and before cryoablation, T cell receptor sequencing of 4 patients showed increased T cell clonality. In this small subset of patients, we provide preliminary evidence that preoperative cryoablation plus ipilimumab and nivolumab is feasible, inducing systemic adaptive immune activation potentially more robust than cryoablation with/without ipilimumab.

Dynamic network curvature analysis of gene expression reveals novel potential therapeutic targets in sarcoma

Network properties account for the complex relationship between genes, making it easier to identify complex patterns in their interactions. In this work, we leveraged these network properties for dual purposes. First, we clustered pediatric sarcoma tumors using network information flow as a similarity metric, computed by the Wasserstein distance. We demonstrate that this approach yields the best concordance with histological subtypes, validated against three state-of-the-art methods. Second, to identify molecular targets that would be missed by more conventional methods of analysis, we applied a novel unsupervised method to cluster gene interactomes represented as networks in pediatric sarcoma. RNA-Seq data were mapped to protein-level interactomes to construct weighted networks that were then subjected to a non-Euclidean, multi-scale geometric approach centered on a discrete notion of curvature. This provides a measure of the functional association among genes in the context of their connectivity. In confirmation of the validity of this method, hierarchical clustering revealed the characteristic EWSR1-FLI1 fusion in Ewing sarcoma. Furthermore, assessing the effects of in silico edge perturbations and simulated gene knockouts as quantified by changes in curvature, we found non-trivial gene associations not previously identified.

Impact of reactive changes on multigene testing: histopathologic analysis of low-grade breast cancers with high-risk 21-gene recurrence scores

PURPOSE

The 21-gene recurrence score (RS) assay predicts the recurrence risk and magnitude of chemotherapy benefit in patients with invasive breast cancer (BC). This study examined low-grade tumors yielding a high-risk RS and their outcomes.Kindly check the edit made in the article titleOk  METHODS: We compared patients with grade 1 BC and a high-risk RS to those with low-risk RS. Histologic sections were reviewed and features reported to elevate the RS were noted, mainly biopsy cavity and reactive stromal changes (BXC).

RESULTS

A total of 54 patients had high-risk RS (median RS of 28, range 26-36). On review, BXC were seen in all cases. Thirty BCs in this group also had low to negative PR. Treatment regimens included: chemoendocrine therapy (63%), endocrine therapy alone (31%) and no adjuvant therapy (6%). There were no additional breast cancer events over a median follow-up of 54.0 months (range 6.2 to 145.3). A total of 108 patients had low-risk RS (median RS of 7, range 0-9). BXC were seen in 47% of cases and none were PR negative. One patient had a recurrence at 64.8 months while the rest had no additional events over a median of 68.1 months (2.4 to 100).

CONCLUSION

We provide further evidence that reactive stromal changes and/or low-PR scores enhance the elevation of the RS. A high-RS result in low grade, PR-positive BC may not reflect actual risk and any suspected discrepancies should be discussed with the management teams. Multigene testing results should be interpreted after correlation with pathologic findings to optimize patient care.

Gene interaction network analysis in multiple myeloma detects complex immune dysregulation associated with shorter survival

The plasma cell cancer multiple myeloma (MM) varies significantly in genomic characteristics, response to therapy, and long-term prognosis. To investigate global interactions in MM, we combined a known protein interaction network with a large clinically annotated MM dataset. We hypothesized that an unbiased network analysis method based on large-scale similarities in gene expression, copy number aberration, and protein interactions may provide novel biological insights. Applying a novel measure of network robustness, Ollivier-Ricci Curvature, we examined patterns in the RNA-Seq gene expression and CNA data and how they relate to clinical outcomes. Hierarchical clustering using ORC differentiated high-risk subtypes with low progression free survival. Differential gene expression analysis defined 118 genes with significantly aberrant expression. These genes, while not previously associated with MM, were associated with DNA repair, apoptosis, and the immune system. Univariate analysis identified 8/118 to be prognostic genes; all associated with the immune system. A network topology analysis identified both hub and bridge genes which connect known genes of biological significance of MM. Taken together, gene interaction network analysis in MM uses a novel method of global assessment to demonstrate complex immune dysregulation associated with shorter survival.

Radiotherapy to regional nodes in early breast cancer: an individual patient data meta-analysis of 14 324 women in 16 trials

BACKGROUND

Radiotherapy has become much better targeted since the 1980s, improving both safety and efficacy. In breast cancer, radiotherapy to regional lymph nodes aims to reduce risks of recurrence and death. Its effects have been studied in randomised trials, some before the 1980s and some after. We aimed to assess the effects of regional node radiotherapy in these two eras.

METHODS

In this meta-analysis of individual patient data, we sought data from all randomised trials of regional lymph node radiotherapy versus no regional lymph node radiotherapy in women with early breast cancer (including one study that irradiated lymph nodes only if the cancer was right-sided). Trials were identified through the EBCTCG's regular systematic searches of databases including MEDLINE, Embase, the Cochrane Library, and meeting abstracts. Trials were eligible if they began before Jan 1, 2009. The only systematic difference between treatment groups was in regional node radiotherapy (to the internal mammary chain, supraclavicular fossa, or axilla, or any combinations of these). Primary outcomes were recurrence at any site, breast cancer mortality, non-breast-cancer mortality, and all-cause mortality. Data were supplied by trialists and standardised into a format suitable for analysis. A summary of the formatted data was returned to trialists for verification. Log-rank analyses yielded first-event rate ratios (RRs) and confidence intervals.

FINDINGS

We found 17 eligible trials, 16 of which had available data (for 14 324 participants), and one of which (henceforth excluded), had unavailable data (for 165 participants). In the eight newer trials (12 167 patients), which started during 1989-2008, regional node radiotherapy significantly reduced recurrence (rate ratio 0·88, 95% CI 0·81-0·95; p=0·0008). The main effect was on distant recurrence as few regional node recurrences were reported. Radiotherapy significantly reduced breast cancer mortality (RR 0·87, 95% CI 0·80-0·94; p=0·0010), with no significant effect on non-breast-cancer mortality (0·97, 0·84-1·11; p=0·63), leading to significantly reduced all-cause mortality (0·90, 0·84-0·96; p=0·0022). In an illustrative calculation, estimated absolute reductions in 15-year breast cancer mortality were 1·6% for women with no positive axillary nodes, 2·7% for those with one to three positive axillary nodes, and 4·5% for those with four or more positive axillary nodes. In the eight older trials (2157 patients), which started during 1961-78, regional node radiotherapy had little effect on breast cancer mortality (RR 1·04, 95% CI 0·91-1·20; p=0·55), but significantly increased non-breast-cancer mortality (1·42, 1·18-1·71; p=0·00023), with risk mainly after year 20, and all-cause mortality (1·17, 1·04-1·31; p=0·0067).

INTERPRETATION

Regional node radiotherapy significantly reduced breast cancer mortality and all-cause mortality in trials done after the 1980s, but not in older trials. These contrasting findings could reflect radiotherapy improvements since the 1980s.

FUNDING

Cancer Research UK, Medical Research Council.

New Frontiers in the Role of Locoregional Therapies in Breast Cancer: Proceedings from the Society of Interventional Radiology Foundation Research Consensus Panel

Emerging evidence regarding the effectiveness of locoregional therapies (LRTs) for breast cancer has prompted investigation of the potential role of interventional radiology (IR) in the care continuum of patients with breast cancer. The Society of Interventional Radiology Foundation invited 7 key opinion leaders to develop research priorities to delineate the role of LRTs in both primary and metastatic breast cancer. The objectives of the research consensus panel were to identify knowledge gaps and opportunities pertaining to the treatment of primary and metastatic breast cancer, establish priorities for future breast cancer LRT clinical trials, and highlight lead technologies that will improve breast cancer outcomes either alone or in combination with other therapies. Potential research focus areas were proposed by individual panel members and ranked by all participants according to each focus area's overall impact. The results of this research consensus panel present the current priorities for the IR research community related to the treatment of breast cancer to investigate the clinical impact of minimally invasive therapies in the current breast cancer treatment paradigm.

Geometric graph neural networks on multi-omics data to predict cancer survival outcomes

The advance of sequencing technologies has enabled a thorough molecular characterization of the genome in human cancers. To improve patient prognosis predictions and subsequent treatment strategies, it is imperative to develop advanced computational methods to analyze large-scale, high-dimensional genomic data. However, traditional machine learning methods face a challenge in handling the high-dimensional, low-sample size problem that is shown in most genomic data sets. To address this, our group has developed geometric network analysis techniques on multi-omics data in connection with prior biological knowledge derived from protein-protein interactions (PPIs) or pathways. Geometric features obtained from the genomic network, such as Ollivier-Ricci curvature and the invariant measure of the associated Markov chain, have been shown to be predictive of survival outcomes in various cancers. In this study, we propose a novel supervised deep learning method called geometric graph neural network (GGNN) that incorporates such geometric features into deep learning for enhanced predictive power and interpretability. More specifically, we utilize a state-of-the-art graph neural network with sparse connections between the hidden layers based on known biology of the PPI network and pathway information. Geometric features along with multi-omics data are then incorporated into the corresponding layers. The proposed approach utilizes a local-global principle in such a manner that highly predictive features are selected at the front layers and fed directly to the last layer for multivariable Cox proportional-hazards regression modeling. The method was applied to multi-omics data from the CoMMpass study of multiple myeloma and ten major cancers in The Cancer Genome Atlas (TCGA). In most experiments, our method showed superior predictive performance compared to other alternative methods.

Associations Between Cancer Predisposition Mutations and Clonal Hematopoiesis in Patients With Solid Tumors

PURPOSE

Clonal hematopoiesis (CH), the expansion of clones in the hematopoietic system, has been linked to different internal and external features such as aging, genetic ancestry, smoking, and oncologic treatment. However, the interplay between mutations in known cancer predisposition genes and CH has not been thoroughly examined in patients with solid tumors.

METHODS

We used prospective tumor-blood paired sequencing data from 46,906 patients who underwent Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT) testing to interrogate the associations between CH and rare pathogenic or likely pathogenic (P/LP) germline variants.

RESULTS

We observed an enrichment of CH-positive patients among those carrying P/LP germline mutations and identified a significant association between P/LP germline variants in ATM and CH. Germline and CH comutation patterns in ATM, TP53, and CHEK2 suggested biallelic inactivation as a potential mediator of clonal expansion. Moreover, we observed that CH-PPM1D mutations, similar to somatic tumor-associated PPM1D mutations, were depleted in patients with P/LP germline mutations in the DNA damage response (DDR) genes ATM, CHEK2, and TP53. Patients with solid tumors and harboring P/LP germline mutations, CH mutations, and mosaicism chromosomal alterations might be at an increased risk of developing secondary leukemia while germline variants in TP53 were identified as an independent risk factor (hazard ratio, 36; P < .001) for secondary leukemias.

CONCLUSION

Our results suggest a close relationship between inherited variants and CH mutations within the DDR genes in patients with solid tumors. Associations identified in this study might translate into enhanced clinical surveillance for CH and associated comorbidities in patients with cancer harboring these germline mutations.

Abstract 6541: Geometry of gene expression network reveals potential novel indicator in Ewing sarcoma

Oncogenic driver mutations in different pediatric sarcoma subtypes have been identified but may not be druggable. In general, identifying novel therapeutic targets and biomarkers for response remains a major challenge. We hypothesize that considering the structure of the interaction network in which the genes operate as a system is crucial for understanding a gene's role. We propose to use the protein interaction network geometry to characterize the shape of network architecture and identify key aspects of direct and indirect cooperation pertaining to the cancer network and prognosis using geometrical methods.

We model gene networks as weighted graphs where edges indicate protein-level interactions and edge weights estimate the strength of the interaction. The Human Protein Reference Database was used to define the gene network topology. RNA-Seq data from pediatric sarcoma tissues extracted from patients treated at MSK (n=12 Ewing sarcoma; n=29 osteosarcoma; n=20 desmoplastic small round cell tumor) was employed to prescribe correlation-based weights to create pediatric sarcoma subtype-specific weighted graphs. The geometry of the weighted gene networks was computed via a discrete notion of Ricci curvature.

Intuitively, the curvature provides a measure of feedback (triangles) in the network. Positive curvature reflects robust communication and ease of information transfer, while negative curvature reflects bridge-like architecture or bottlenecks of information flow. We utilized a dynamic (multi-scale) notion of curvature to quantify the functional associations between genes, computed as a function of scale between diffusion processes initially localized on each node (i.e., gene). The curvature becomes more positive on edges between communal genes and more negative on bridge-like edges between communities, until reaching the critical scale. Curvature therefore, as we demonstrate, partitions the cancer networks into functionally associated communities.

Community detection by removing bridge-edges, determined as edges with negative curvature at the critical scale, revealed sarcoma subtype-specific preferential gene associations. In particular, we agnostically found the EWSR1-FLI1 association in a cluster that was unique to the Ewing sarcoma network. Interestingly, we found ETV6 in the same community as the characteristic Ewing sarcoma EWSR1-FLI1 feature, suggesting a novel implication of ETV6 in Ewing sarcoma. These results suggest that persisting communities found by leveraging the cancer network geometry may identify potential mechanisms of drug resistance and actionable therapeutic targets.

Citation Format: Rena Elkin, Jung Hun Oh, Filemon Dela Cruz, Larry Norton, Joseph O. Deasy, Andrew L. Kung, Allen R. Tannenbaum. Geometry of gene expression network reveals potential novel indicator in Ewing sarcoma [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 6541.

Abstract 6591: A universal atlas of cellular and oncogenic phenotypes

Tumors and healthy tissues exhibit gene expression variability in many of the same pathways. We propose that these commonalities result from a performance trade-off between universal cellular phenotypes; each phenotype is defined by an orthogonal gene expression profile identified using unsupervised dimensionality reduction. Using two publicly available RNA-seq datasets (n=54 normal tissues; n=1504 cancer cell lines), we show that both healthy and cancerous cells occupy a trade-off between five canonical phenotypes: OxPhos, Warburg, Fibroblastic, Immune, and Growth. Each cell is assigned a phenotype score that, as we demonstrate, predicts differential drug sensitivities and mutational signatures, even among cancers of the same tissue type. Since these phenotype scores are defined using only healthy tissues, they can be generally applied to other diseases as well.

Citation Format: Corey Weistuch, Kevin Murgas, Ken Dill, Larry Norton, Joseph Deasy, Allen Tannenbaum. A universal atlas of cellular and oncogenic phenotypes [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 6591.

Abstract 2061: Protein network analysis uncovers a poor-survival subtype in multiple myeloma

Multiple myeloma (MM) prognosis incorporates a variety of metrics including treatment received, clinical factors, and genomic characteristics, with several specific genomic features predicting for shorter progression free survival (PFS). No study to date has integrated genomic data from a systems view, incorporating interactions between biomarkers in a network. We use a geometric network analysis that integrates complex interactions to characterize patterns of biological behavior not captured by individual genomic events. The methodology is mathematically well-defined and has no fitting parameters. We hypothesized that such a systems mathematical approach applied to gene interaction networks may delineate biologically relevant MM subtypes and potential new therapeutic targets. We overlaid RNA-Seq and copy number alteration data from the MMRF CoMMpass study (IA19) on a gene interactome derived from the Human Protein Reference Database using a novel graph metric of network robustness — Ollivier-Ricci curvature (ORC). Results were clustered, with the optimal number determined via silhouette score. Survival analysis for PFS was performed employing Kaplan-Meier and log-rank tests. A differential gene expression analysis between high and low risk groups was conducted. Differences in scalar ORC between the low-risk and high-risk groups were examined and contextualized using a pathway analysis. Pathway analysis was performed using the Broad Institute’s Gene Set Enrichment Analysis tool and the pathways used are from the hallmark gene set from the Human MSigDB collection. The dataset included 659 patients and the incorporated protein-protein interactions resulted in a network with 8,468 nodes and 33,695 edges. The ORC analysis discovered 6 clusters, with specific genomic features being associated with clusters predicting for long [hyperdiploidy, t(11:14)], and short [t(4;14), MAF/MAFB translocations] PFS. A differential gene expression analysis comparing the high risk and low risk groups identified 118 key genes. These genes were associated with various pathways both known and unknown to be associated with multiple myeloma, including mitotic spindle, DNA repair, inflammatory response, and the P53 pathways. Further scalar curvature analysis showed differences in the apoptosis, TGF beta signaling, and other signaling pathways. In summary, we applied the geometric network analysis tool ORC to multi-omics data in MM represented as biological networks to identify individuals at high risk of short PFS and relevant biological correlates. Decreased robustness of signaling near immune-related genes was associated with shorter survival, highlighting the plausible utility of using these methods to uncover new biological insights.

Citation Format: Anish K. Simhal, Kylee H. Maclachlan, Rena Elkin, Jiening Zhu, Saad Z. Usmani, Jonathan J. Keats, Larry Norton, Joseph O. Deasy, Jung Hun Oh, Allen Tannenbaum. Protein network analysis uncovers a poor-survival subtype in multiple myeloma [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 2061.

Abstract OT1-19-01: A Single Arm Phase 2 Study of Peri-Operative Checkpoint-Mediated Immune Therapy and Cryoablation in Women with Hormone Receptor-Negative, HER2-Negative Early Stage/Resectable Breast Cancer

Background: Local tumor destruction with cryoablation (cryo) induces inflammation and releases antigens that can activate tumor-specific immune responses. Pre-clinically, cryo with immune checkpoint inhibition (ICI)-augmented tumor-specific immune responses and prevented recurrence. Clinically, we established that peri-operative (peri-op) cryo with ipilimumab (ipi) +/- nivolumab (nivo) was not only safe in patients (pts) with operable, early stage breast cancer (ESBC) but also generated robust intra-tumoral and systemic immune responses. In this phase 2 study, we evaluate the disease specific impact of peri-op ICI in women with residual triple negative breast cancer (TNBC) after neoadjuvant chemotherapy (NAC), a subset at high risk of early relapse. Methods: Eligible pts are ≥18y, with ER &lt; 10%, PR &lt; 10%, HER2 negative (per ASCO/CAP definition), ≥ 1.0 cm, residual operable disease after taxane-based NAC. Approximately 80 pts will be enrolled and treated with ipi/nivo/cryo followed by breast surgery and adjuvant nivo across multiple institutions. Pts undergo percutaneous, image-guided cryo with concurrent research core biopsy 7-10 days prior to surgery and will receive ipi (1mg/kg IV) with nivo (240mg IV) 1 to 5 days prior to cryo. After surgery, pts will receive 3 additional doses of nivo at 240mg IV Q2 weeks. Adjuvant capecitabine is recommended for all patients per local standard-of-care. Patients will be stratified by NAC platinum administration, NAC anthracycline administration, and clinical nodal status (positive versus negative). The primary endpoint is 3-year Event Free Survival (EFS). Secondary endpoints include Invasive Disease-Free Survival (IDFS), Distant Disease-Free Survival (DDFS), overall survival (OS) and safety. Exploratory correlative studies will be performed on tumor and serum to characterize the immunologic impact of the intervention and to explore predictors of efficacy and toxicity. Funding sources: Susan G. Komen, ASCO Conquer Cancer Foundation, Breast Cancer Research Foundation, Bristol-Myers Squibb, BTG International Ltd. NCT03546686

Citation Format: Heather McArthur, Elizabeth Comen, Yolanda Bryce, Stephen Solomon, Jorge Henrique Santos Leal, Christina DiLauro Abaya, Cristal Martinez, Reva Basho, Dorothy Park, Philomena McAndrew, Brigid Larkin, William Mills, David B. Page, Staci Mellinger, Nicole Fredrich, Nicole Moxon, Sangeetha Reddy, Meredith Carter, Sujata Patil, Larry Norton. A Single Arm Phase 2 Study of Peri-Operative Checkpoint-Mediated Immune Therapy and Cryoablation in Women with Hormone Receptor-Negative, HER2-Negative Early Stage/Resectable 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 OT1-19-01.

Abstract P4-02-01: Efficacy of HER2 ADCs against HER2 inhibitor resistance alterations in the PI3K and MAPK pathways in HER2-positive breast cancer

Background: HER2 positive (HER2+) breast cancers harboring downstream MAPK or PI3K pathway alterations manifest persistent downstream signaling on anti-HER2 inhibitors with metastatic patients having worse outcomes on first line trastuzumab and pertuzumab (HP) therapy. However, HER2 antibody-drug conjugates (ADCs) are not as dependent upon potent signal transduction inhibition to exert their antitumor effects. To further investigate, we sought to determine whether MAPK and/or PI3K alterations affect the biologic or clinical outcomes of patients and models receiving HER2 ADCs. Methods: We performed prospective genomic sequencing using MSK-IMPACT on patients with advanced HER2+ breast cancer who received trastuzumab emtansine (T-DM1) in the metastatic setting between March 2013 and July 2021. We collected detailed information on clinical outcomes and correlates through our institutional IRB-approved retrieval process. HER2/ER/PR status at the time of metastatic recurrence were defined as per ASCO/CAP guidelines. Cox proportional hazard models were used to determine the association between MAPK and PI3K pathways alterations and progression-free survival (PFS) on T-DM1. Common mutations associated with outcomes were modeled in HER2+ breast cancer cell lines using short hairpin RNAs and CRISPR/Cas9, and the sensitivity to HER2 ADC was evaluated via cell proliferation and xenograft assays. Results: We identified 185 HER2+ breast cancer patients treated with T-DM1 at any line (median: 5) whose primary (N=65) or metastatic (N=120) tumor samples were sequenced. Median age was 55 (range: 20-87). The majority of the patients received T-DM1 in 2nd or 3rd line (52%) and received prior trastuzumab or HER2 TKI in metastatic setting (96%). 74/185 (40%) had de novo metastatic breast cancer and 119/185 (64%) had ER/PR+/HER2+ disease. Pathogenic activating alterations involving the MAPK pathway were observed in 14% of patients with the most frequent alterations being ERBB2 activating mutations (42%) and NF1 loss (34%). PI3K pathway alterations were identified in 42% of the patients, the majority being activating mutations of PIK3CA (87%). MAPK alterations were significantly enriched in the metastatic tumors compared to the treatment-naïve primaries (20% vs 3%, p=0.001), while PI3K alterations were not (44% vs 40%, p=0.6). To reduce the possible confounding resistance mechanisms induced by prior treatment, we restricted the survival analyses to patients who received T-DM1 up to 3rd line of therapy (N=100). On multivariable analysis adjusted for ER/PR status (positive vs negative), stage at the presentation of metastatic disease (de novo metastatic vs recurrence), treatment line and type of sequenced sample (primary vs metastatic), patients with MAPK (N=14) and PI3K (N= 38) alterations had similar PFS compared to wild type (HR 1.20, 95%CI 0.62-2.30, p=0.6 and HR 1.23, 95%CI 0.77-1.95, p=0.4, respectively). Similar results were found in the combined analysis including alterations in either pathway (N=48, HR 1.28, 95%CI 0.81-2.04, p=0.3). To verify the antiproliferative effect of HER2 ADCs on breast cancer cells with MAPK pathway activation, we depleted NF1 in a panel of HER2+ breast cancer cell lines. Consistently, MAPK-altered cell lines were sensitive to FDA-approved HER2 ADCs including trastuzumab deruxtecan (T-DXd). Conclusions: In contrast to H/P therapy, T-DM1 therapy was equally effective in tumors with downstream PI3K or MAPK alterations and wild type tumors. Expanded analysis on a larger cohort, including a subgroup of patients treated with novel HER2 ADCs such as T-DXd will be presented. The characterization of PI3K and MAPK pathways status in metastatic HER2+ breast cancer may inform prioritization of treatment options.

Citation Format: Emanuela Ferraro, Anton Safonov, Yuan Chen, Charlie White, Antonio Marra, Mehnaj Ahmed, Barbara Acevedo, Chau T Dang, Shanu Modi, David B. Solit, Larry Norton, Mark E. Robson, Jorge Reis-Filho, Sarat Chandarlapaty, Pedram Razavi. Efficacy of HER2 ADCs against HER2 inhibitor resistance alterations in the PI3K and MAPK pathways in HER2-positive 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 P4-02-01.

Abstract P4-02-18: Impact of clonal hematopoiesis on disease progression following CDK4/6 inhibitor therapy

Background Clonal Hematopoiesis (CH) is a well-established risk factor for adverse clinical outcomes including all-cause mortality, cardiovascular disease, and progression to hematologic malignancies. The presence of CH has been shown to adversely impact overall survival in non-hematologic cancers, however whether CH modulates response to specific therapies in breast cancer is not known. Here we investigate the impact of CH mutations on disease progression in patients with metastatic estrogen receptor (ER) positive breast cancer undergoing treatment with first line CDK4/6 inhibitors and endocrine therapy (CDK4/6i+ET). Methods We analyzed data from a well annotated cohort of patients with ER+ breast cancer who received endocrine therapy and CDK4/6 inhibitors. All patients underwent prospective tumor and matched WBC sequencing utilizing the MSK-IMPACT assay. CH variants were detected in blood samples utilizing the well-validated variant detection and filtration pipeline of MSK-IMPACT. CH mutations were defined as putative drivers (CH-PD) or non-putative drivers (CH) as previously described. To ensure the presence of CH at the time of therapy initiation, only patients who had CH sampling performed from 6 months before through 4 months after initiation of CDK4/6i+ET were included. We compared progression free survival (PFS) in patients with and without CH, as well as by CH-PD status and DNMT3A CH mutations. We investigated clinical covariates including type of endocrine therapy, receipt of prior neoadjuvant or adjuvant chemotherapy, and age at start of CDK4/6i+ET. Results The final cohort was comprised of 378 patients, of whom 135 (35.7%) had CH. The median time between sample collection and CDK4/6i+ET initiation was 0 (IQR -0.79 to 0.47 months). Patients with CH were older at time of therapy initiation (median 63.0 versus 54.7 years, p &lt; 0.001). There were no significant differences between groups in terms of endocrine therapy (aromatase inhibitor or fulvestrant), prior chemotherapy, and time from CH sample collection to CDK4/6i+ET start. Univariate Cox-proportional hazard analysis did not reveal a difference between progression free survival and overall CH (HR 0.96, 95% CI 0.75 – 1.23, p = 0.76), CH-PD (HR 1.05, 0.77 – 1.43, p = 0.77), or DNMT3A mutations (HR 1.12, 0.80 – 1.60, p = 0.52) compared to patients without CH. Interestingly, age less than 60 years was found to be associated with PFS outcome (univariate HR 1.57, 1.22 – 2.01, p = 0.0004). Multivariate analysis adjusted for endocrine therapy partner and age at CDK4/6i+ET therapy did not reveal an association between outcome and overall CH (HR 1.07, 0.83 – 1.39, p = 0.59). In patients younger than age 60, presence of overall CH did not confer a significant PFS difference (HR 0.90, 0.63 – 1.29, p = 0.57). In the subset of patients older than 60 (n = 168) presence of CH conferred numerically, but not statistically, significant shorter PFS (HR 1.41 [0.96 – 2.09], p = 0.08). In this population, CH-PD conferred a shorter PFS (HR 1.75, 1.12 – 2.72, p = 0.02). Conclusion We found that CH, CH-PD and DNMT3A CH mutations did not affect PFS among metastatic ER+ breast cancer patients treated with first line CDK4/6 inhibitors. Younger age was associated with increased risk of progression, warranting further investigation. In the subset of patients with age older than 60, CH-PD conferred a shorter PFS. Further data, incorporating records of dose reductions, will be presented at the meeting.

Citation Format: Jacqueline Tao, Pablo Sanchez Vela, Anton Safonov, Emanuela Ferraro, Sebastia Franch Exposito, Kamal Menghrajani, Ryan Ptashkin, Elizabeth Comen, Lior Z. Braunstein, Mark E. Robson, Sarat Chandarlapaty, Jorge Reis-Filho, Michael Berger, Ahmet Zehir, Larry Norton, Ross Levine, Pedram Razavi. Impact of clonal hematopoiesis on disease progression following CDK4/6 inhibitor 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 P4-02-18.

Multiomics in primary and metastatic breast tumors from the AURORA US network finds microenvironment and epigenetic drivers of metastasis

The AURORA US Metastasis Project was established with the goal to identify molecular features associated with metastasis. We assayed 55 females with metastatic breast cancer (51 primary cancers and 102 metastases) by RNA sequencing, tumor/germline DNA exome and low-pass whole-genome sequencing and global DNA methylation microarrays. Expression subtype changes were observed in ~30% of samples and were coincident with DNA clonality shifts, especially involving HER2. Downregulation of estrogen receptor (ER)-mediated cell-cell adhesion genes through DNA methylation mechanisms was observed in metastases. Microenvironment differences varied according to tumor subtype; the ER+/luminal subtype had lower fibroblast and endothelial content, while triple-negative breast cancer/basal metastases showed a decrease in B and T cells. In 17% of metastases, DNA hypermethylation and/or focal deletions were identified near HLA-A and were associated with reduced expression and lower immune cell infiltrates, especially in brain and liver metastases. These findings could have implications for treating individuals with metastatic breast cancer with immune- and HER2-targeting therapies.

Targeting stressor-induced dysfunctions in protein-protein interaction networks via epichaperomes

Diseases are manifestations of complex changes in protein-protein interaction (PPI) networks whereby stressors, genetic, environmental, and combinations thereof, alter molecular interactions and perturb the individual from the level of cells and tissues to the entire organism. Targeting stressor-induced dysfunctions in PPI networks has therefore become a promising but technically challenging frontier in therapeutics discovery. This opinion provides a new framework based upon disrupting epichaperomes - pathological entities that enable dysfunctional rewiring of PPI networks - as a mechanism to revert context-specific PPI network dysfunction to a normative state. We speculate on the implications of recent research in this area for a precision medicine approach to detecting and treating complex diseases, including cancer and neurodegenerative disorders.

Solid-basaloid variant of adenoid cystic carcinoma of the breast with near complete response to neoadjuvant chemotherapy

Breast adenoid cystic carcinoma (AdCC) is a rare subtype of triple negative breast cancer. Two morphologic variants are described, namely classic AdCC (C-AdCC) and solid basaloid (SB-AdCC). Recent studies have shown that the SB-AdCC variant has significantly worse prognosis than C-AdCC. Due to the rarity of SB-AdCC, no standard recommendations are available for its management. Data on the use and benefit of chemotherapy in patients with SB-AdCC are sparse and the response to neoadjuvant chemotherapy has not been reported. We present the clinical and pathologic findings of a patient with SB-AdCC treated with neoadjuvant chemotherapy who achieved a remarkable pathologic response.

Abstract 1928: Prediction of neoadjuvant treatment outcomes with multimodal data integration in breast cancer

Neoadjuvant chemotherapy (NAC) is the standard of care for selected patients with high-risk early-stage breast cancer with pathologic complete response (pCR) being the most prominent predictor of favorable outcomes. Here, we sought to study the predictive capacity of integrating orthogonal diagnostic measures on predicting pCR relative to standard clinicopathologic features.

We developed a computational model integrating radiology and pathology images, and tumor genomics to automatically predict pCR from multimodal data. We present an interim analysis on a cohort of 957 patients with at least one available pre-NAC data modality. The baseline AUC for pCR prediction by a trained and tested logistic regression model on 857 patients using standard clinicopathologic features including receptor subtype, demographic information, and stage was 0.77. MR images were input into a convolutional neural network (CNN) and a radiomics model.

The trained CNN and radiomics models using selected images of 576 patients with pre-NAC MR images achieved AUCs of 0.65 and 0.60 on 164 hold-out test cases, respectively.

We trained a multiple instance learning-based weakly supervised learning (MIL-WSL) model using 537,762 extracted tiles from whole slide images (WSI) of digital histopathology scans from 522 patients. The MIL-WSL model achieved AUC of 0.63 for pCR prediction on a hold-out test set of pre-NAC biopsies from 239 patients. A feature based classifier trained on 76 cases using tumor genomic features such as mutational burden, microsatellite instability, fraction genome altered, ploidy, purity, mutation and copy number alterations in selected genes achieved an AUC of 0.72 on 83 hold-out test cases.

We then combined unimodal radiology, histopathology, and genomic predictions in a deterministic manner. This multimodal combination on an independent 68-patient test set achieved an AUC of 0.84, indicating increased power to resolve pCR than any modality alone, and over clinicopathologic baseline.

Together, we present approaches to train models end-to-end using tensor fusion networks and attention-gating combined with MIL. Automated multimodal methods are here shown to improve prediction over established clinical parameters alone, motivating our ongoing efforts to refine and improve the model so as to achieve higher levels of efficiency. We anticipate these interim results will be further improved through refinement of input features and increasing the number of patients included in the final validation cohort.

Citation Format: Pegah Khosravi, Elizabeth J. Sutton, Justin Jee, Timothy Dalfonso, Christopher J. Fong, Doori Rose, Edaise M. Da Silva, Armaan Kohli, David Joon Ho, Mehnaj S. Ahmed, Danny Martinez, Anika Begum, Elizabeth Zakszewski, Andrew Aukerman, Yanis Tazi, Katja Pinker-Domenig, Sarah Eskreis-Winkler, Atif J. Khan, Edi Brogi, Elizabeth Morris, Sarat Chandarlapaty, George Plitas, Simon Powell, Monica Morrow, Larry Norton, Jianjiong Gao, Mark Robson, Hong Zhang, Sohrab Shah, Pedram Razavi, MSK-MIND Consortium. Prediction of neoadjuvant treatment outcomes with multimodal data integration in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1928.

Abstract 961: TCF7 promotes a mammary cancer-stem-like phenotype leading to metastasis via potentiation of a hybrid epithelial/mesenchymal (E/M) phenotype

Cancer stem cells (CSCs) are a minor population of carcinoma cells that can self-renew and give rise to differentiated progenitors that form the bulk of the tumor. CSCs cause tumor recurrence, chemoresistance and metastasis. The epithelial-to-mesenchymal transition (EMT) promotes tumor cell migration, invasion and cancer stem cell properties. The Wnt signaling pathway is a major driver of cancer stemness and is regulated by the TCF/LEF family of transcription factors. Using loss and gain of function of TCF7 (TCF1) in mouse and human breast cancer cells, we were able to demonstrate that TCF7 promotes cancer stemness through striking regulation of the EMT process. TCF7 knockdown in PyMT mammary tumor cells induced luminal epithelial differentiation, resulting in inhibition of oncosphere formation, migration, tumor growth and lung colonization. However, in keeping with a changing view of EMT as a strictly binary process, we found that TCF7 shifts tumor cells towards a hybrid epithelial/mesenchymal state (E/M) rather than a mesenchymal (M) state. This E/M population was shown to carry stemness and metastatic properties and to be interestingly represented by a small “stem-like” subpopulation in triple negative breast cancer (TNBC) cells. Using CD44 and CD104 (integrin β4) flow cytometry to isolate E/M cells from normal MCF10A and basal-like MDA-MB-468 breast cancer cells, we show that TCF7, Snail, and GSK3β phosphorylation were all highly enriched in this population whereas Zeb-1 (a marker of mesenchymal cells), was absent from E/M cells. These data support a model whereby TCF7 potentiates Wnt signaling which in turn activates GSK3β phosphorylation, resulting in Snail upregulation and enrichment of cells in the E/M state that is conducive of stemness and metastasis.

Citation Format: Huizhi Liang, Outhiriaradjou Benard, Zuen Ren, Kimita Suyama, Larry Norton, Rachel B. Hazan. TCF7 promotes a mammary cancer-stem-like phenotype leading to metastasis via potentiation of a hybrid epithelial/mesenchymal (E/M) phenotype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 961.

Abstract 968: Loss of glutathione peroxidase 2 promotes epithelial to mesenchymal transition and breast cancer metastasis

The processes regulating tumor metastasis are multivariate and complex. Redox regulation of the tumor phenotype by GPx2 knockdown (KD) in breast cancer led us to uncover dramatic effects on spontaneous metastasis. Analysis of single cell RNA sequencing (scRNAseq) data from GPx2 KD tumor and control tumor, revealed that both tumors were comprised of several luminal-like tumor cell clusters and one mesenchymal-like cell cluster (cluster 3). Notably, GPx2 KD promoted a significant increase in the size of mesenchymal cells (cluster 3) relative to control, which might be due to the stimulation of epithelial-to-mesenchymal transition (EMT) in response to GPx2 loss. In support of this view, GPx2 KD stimulated an increase in mRNA expression of basal/mesenchymal (KRT5, KRT14, KRT17, Vimentin, Twist1, Twist2, CDH2) genes and a decrease in mRNA expression of epithelial/luminal (Cldn7 and Epcam) genes, especially in cluster 3. Moreover, GPx2 KD upregulated mRNA expression of basal/mesenchymal (Twist2, CDH2, and KRT14) genes in most luminal-like clusters expressing epithelial/luminal (Epcam, Cldn3/7, CDH1, KRT8/18) genes, implying these clusters may be undergoing EMT transition in a hybrid epithelial/mesenchymal state in response to GPx2 loss. Validation of these data in cell lines and tumors showed that GPx2 KD dramatically enhanced EMT via activation of ROS/HIF1α-mediated signaling. Importantly, these effects were reversed by GPx2 re-expression or HIF1α inhibition, which was capable of suppressing EMT and metastasis. Collectively, these results indicate that GPx2 loss promotes breast cancer metastasis by stimulating EMT due to HIF1α signaling, highlighting the impact of GPx2 and HIF1 on therapeutic intervention in metastasis.

Citation Format: Zuen Ren, Huizhi Liang, Malindrie Dharmaratne, Miriam Morales-Gallego, Atefeh Taherian Fard, Jessica Mar, Kimita Suyama, Outhiriaradjou Benard, Michael B. Prystowsky, Larry Norton, Rachel B. Hazan. Loss of glutathione peroxidase 2 promotes epithelial to mesenchymal transition and breast cancer metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 968.

Impact of clonal hematopoiesis on tumor control following radiation therapy

3145

Background: Clonal hematopoiesis (CH) has well established associations with adverse clinical outcomes including all-cause mortality, cardiovascular disease, and progression to hematologic malignancy. The presence of CH has also been demonstrated to adversely impact survival from non-hematologic cancers, however whether CH may modulate response to radiation therapy (RT) in solid tumors is not known. Here we investigate the potential impact of CH mutations on radiation outcomes. Methods: We analyzed data from two previously well annotated cohorts of patients with tumors harboring somatic ATM mutations (n = 358) and FAT1 mutations (n = 365) who received RT and underwent prospective tumor and matched WBC sequencing utilizing the MSK-IMPACT assay. CH variants were detected in the blood samples utilizing a well-validated variant detection and filtration pipeline. Given that pathogenic mutations in ATM have been shown to be strongly associated with improved response to RT, these patients were excluded to avoid confounding. Additionally, patients with blood sampling for CH assessment that occurred more than 6 months after RT were excluded to address the possibility of therapy-related CH. We compared outcomes including irradiated tumor progression in patients with and without CH. Results: The final analysis consisted of 412 patients who underwent 811 total courses of radiation. A wide spectrum of solid tumor types were represented, most commonly non-small cell lung cancer (32.5%) and breast cancer (11.9%). A total of 161 patients (39.0%) had CH, with the most commonly mutated genes being DNMT3A (25.6%), PPM1D (6.2%), TET2 (5.8%), and TP53 (5.0%), consistent with prior studies of CH. Patients with CH were older at blood sample collection (67.6 vs 60.2 years, p < 0.001), reflecting an expected increase in CH burden with age. Fine Gray competing risks analysis, with death treated as a competing event and with clustering around patient identifier, showed no difference in irradiated tumor progression between patients with and without CH (HR 1.03, 95% CI 0.69 – 1.53, p = 0.896). Similarly, subanalyses by CH variant allele frequency and putative CH-driver mutations did not reveal an association between CH and response to RT. A hypothesis generating subgroup analysis by common cancer types, however, suggested that CH was associated with increased risk of progression post-radiation in prostate (HR 4.68, 1.14 – 19.1) and thyroid (HR 3.13, 1.55 – 6.34) cancer cohorts, warranting further investigation. Conclusions: We found no difference in irradiated tumor progression among patients who did and did not have CH. There may be an association between CH and poor radiation outcomes in certain cancer types, and further studies are needed to clarify the specific clinical and genomic factors that may influence radiation response.

Allelic dosage of RB1 drives CDK4/6 inhibitor treatment resistance in metastatic breast cancer

1010

Background: We recently reported inferior outcomes to CDK4/6 inhibitors and endocrine therapy (CDK4/6i-ET) associated with germline BRCA2 (g BRCA2) in a cohort of estrogen receptor (ER) positive breast cancers. Co-occurrence of gBRCA2 with loss of heterozygosity (LOH) of neighboring RB1 was found to portend particularly poor outcomes. Here, we sought to define the effects of pre-treatment RB1 allelic copy number status on outcomes of CDK4/6i-ET and the likelihood of developing RB1 loss-of-function (LOF) mutations on CDK4/6i through the analysis of an expanded cohort of metastatic ER+ breast cancer patients. Methods: Patients who underwent sequencing on MSK-IMPACT from April 2014 to May 2021 were included. For every sample preceding CDK4/6i-ET, we performed FACETS to infer RB1 allele specific copy number, ploidy, tumor purity and fraction genome altered (FGA). Patients were categorized based on RB1 allelic status: HetLoss (total of one allelic copy), copy neutral LOH (CNLOH), other allelic imbalance including all other aneuploidy states, and diploid. Progression free survival (PFS) was assessed using univariate and multivariate Cox proportional hazard models adjusted for ET partner and FGA. Firth penalized logistic regression was used to study association of pre-treatment RB1 status with acquired RB1 LOF variants in paired post-CDK4/6i samples. Results: Of 2,630 potentially eligible patients, 279 patients had genomic sequencing performed prior to 1st line CDK4/6i-ET. Of these, 75 (26.8%) exhibited RB1 HetLoss, 39 (14.0%) had CNLOH of RB1, 111 (39.7%) exhibited diploid RB1 state, while 54 (19.4%) had other patterns of RB1 allelic imbalance. All non-diploid RB1 states were associated with significantly shortened PFS relative to diploid (univariate HetLoss HR: 2.05, 95% CI: 1.42, 2.97; CNLOH HR: 2.08, 95% CI: 1.32, 3.25; other imbalance HR: 1.70, 95% CI: 1.11, 2.58). Only HetLoss remained significant when adjusted for FGA (HR 1.61, 95% CI: 1.09, 2.38, p = 0.017). RB1 LOF was rare in pre-CDK4/6i tumors (< 1%); excluding these cases did not change our results. Of the 176 patients with paired pre- and post-CDK4/6i samples, only RB1 HetLoss in pre-CDK4/6i sample was significantly associated with development of RB1 LOF mutations in post-CDK4/6i sample (18.4%) as compared to diploid (4.2%, OR 4.25, 95% CI 1.02, 17.7, p = 0.047). These results indicate that tumors with one functional copy of RB1 are more likely to acquire RB1 LOF on CDK4/6i to achieve biallelic RB1 loss as a mechanism of CDK4/6i resistance. Conclusions: We demonstrate that LOH and allelic imbalance of RB1 are associated with shorter PFS on CDK4/6-ET. We postulate this may occur partly as a result of more frequent acquired RB1 LOF mutations under selective pressure of CDK4/6i. These data supports the implementation of more refined allele-specific copy number methods and identifies a high-risk population for escalated monitoring and treatment approaches.

A single-arm, phase 2 study of perioperative ipilimumab, nivolumab, and cryoablation in women with hormone receptor-negative, HER2-negative, early-stage/resectable breast cancer

TPS617

Background: Local tumor destruction with cryoablation (cryo) induces inflammation and releases antigens that can activate tumor-specific immune responses. Pre-clinically, cryo with checkpoint inhibition augmented tumor-specific immune responses and prevented recurrence. Clinically, we established that peri-operative (peri-op) cryo with ipilimumab (ipi) +/- nivolumab (nivo) was not only safe in patients (pts) with operable, early stage breast cancer (ESBC) but also generated robust intra-tumoral and systemic immune responses. In this phase 2 study, we evaluate the disease specific impact of peri-op ipi/nivo/cryo in women with residual triple negative breast cancer (TNBC) after neoadjuvant chemotherapy (NAC), a subset at high risk of early relapse. Methods: Eligible pts are ≥18y, with ER < 10%, PR < 10%, HER2 negative (per ASCO/CAP definition), ≥ 1.0 cm, residual operable disease after taxane-based NAC. Approximately 80 pts will be enrolled and treated with ipi/nivo/cryo followed by breast surgery and adjuvant nivo. Pts undergo percutaneous, image-guided cryo with concurrent research core biopsy 7-10 days prior to surgery and will receive ipi (1mg/kg IV) with nivo (240mg IV) 1 to 5 days prior to cryo. After surgery, pts will receive 3 additional doses of nivo at 240mg IV Q2 weeks. Adjuvant capecitabine is recommended for all patients per local standard-of-care. Patients will be stratified by NAC platinum administration, NAC anthracycline administration, and clinical nodal status (positive versus negative). The primary endpoint is 3-year Event Free Survival (EFS). Secondary endpoints include Invasive Disease-Free Survival (IDFS), Distant Disease-Free Survival (DDFS), overall survival (OS) and safety. Exploratory correlative studies will be performed on tumor and serum to characterize the immunologic impact of the intervention and to explore predictors of efficacy and toxicity. Clinical trial information: NCT03546686.

Brain radiotherapy, tremelimumab-mediated CTLA-4-directed blockade +/- trastuzumab in patients with breast cancer brain metastases

Breast cancer brain metastases (BCBM) are a common and devastating complication of metastatic breast cancer with conventional systemic therapies demonstrating limited effectiveness. Consequently, radiotherapy (RT) ± surgery remains the cornerstone of BCBM management. Because preclinical and clinical evidence indicate that immune checkpoint blockade (ICB) may synergize with RT to promote systemic tumor regression, we explored the safety and efficacy of RT and concurrent tremelimumab-mediated cytotoxic T-lymphocyte associated protein 4 (CTLA-4) ICB with tremelimumab ± HER2-directed therapy with trastuzumab for BCBM. Eligible patients had BCBM indicated for brain RT. A Simon two-stage design was adopted to evaluate the efficacy of tremelimumab and RT in 20 patients with human epidermal growth factor receptor normal (HER2−) BCBM. The safety of concurrent RT, tremelimumab, and trastuzumab was evaluated in a cohort of 6 HER2+ patients. The primary endpoint was 12-week non-central nervous system (CNS) disease control rate (DCR). Secondary endpoints included safety, survival, and CNS response. Exploratory correlatives included characterization of peripheral blood immune responses among exceptional responders. Tremelimumab plus RT ± trastuzumab was tolerated with no treatment-related grade 4 adverse events reported. The 12-week non-CNS DCR was 10% (2/20) in the HER2− cohort and 33% (2/6) in the HER2+ cohort. One patient with HER2+ disease experienced a durable partial response with evidence of peripheral T-cell activation. Thus, tremelimumab and RT ± trastuzumab was tolerated. Although modest clinical activity was observed in the HER2- efficacy cohort, encouraging responses were observed in the HER2+ safety cohort. Consequently, a trial to determine efficacy in HER2+ BCBM is planned.

Clinical Trial Registration Number: NCT02563925.

Incidence of brain metastases in patients with early HER2-positive breast cancer receiving neoadjuvant chemotherapy with trastuzumab and pertuzumab

The addition of pertuzumab (P) to trastuzumab (H) and neoadjuvant chemotherapy (NAC) has decreased the risk of distant recurrence in early stage HER2-positive breast cancer. The incidence of brain metastases (BM) in patients who achieved pathological complete response (pCR) versus those who do not is unknown. In this study, we sought the incidence of BM in patients receiving HP-containing NAC as well as survival outcome. We reviewed the medical records of 526 early stage HER2-positive patients treated with an HP-based regimen at Memorial Sloan Kettering Cancer Center (MSKCC), between September 1, 2013 to November 1, 2019. The primary endpoint was to estimate the cumulative incidence of BM in pCR versus non-pCR patients; secondary endpoints included disease free-survival (DFS) and overall survival (OS). After a median follow-up of 3.2 years, 7 out of 286 patients with pCR had a BM while 5 out of 240 non-pCR patients had a BM. The 3-year DFS was significantly higher in the pCR group compared to non-pCR group (95% vs 91 %, p = 0.03) and the same trend was observed for overall survival. In our cohort, despite the better survival outcomes of patients who achieved pCR, we did not observe appreciable differences in the incidence of BM by pCR/non-pCR status. This finding suggests that the BM incidence could not be associated with pCR. Future trials with new small molecules able to cross the blood brain barrier should use more specific biomarkers rather than pCR for patients' selection.

Aromatase inhibitors versus tamoxifen in premenopausal women with oestrogen receptor-positive early-stage breast cancer treated with ovarian suppression: a patient-level meta-analysis of 7030 women from four randomised trials

BACKGROUND

For women with early-stage oestrogen receptor (ER)-positive breast cancer, adjuvant tamoxifen reduces 15-year breast cancer mortality by a third. Aromatase inhibitors are more effective than tamoxifen in postmenopausal women but are ineffective in premenopausal women when used without ovarian suppression. We aimed to investigate whether premenopausal women treated with ovarian suppression benefit from aromatase inhibitors.

METHODS

We did a meta-analysis of individual patient data from randomised trials comparing aromatase inhibitors (anastrozole, exemestane, or letrozole) versus tamoxifen for 3 or 5 years in premenopausal women with ER-positive breast cancer receiving ovarian suppression (goserelin or triptorelin) or ablation. We collected data on baseline characteristics, dates and sites of any breast cancer recurrence or second primary cancer, and dates and causes of death. Primary outcomes were breast cancer recurrence (distant, locoregional, or contralateral), breast cancer mortality, death without recurrence, and all-cause mortality. As distant recurrence invariably results in death from breast cancer several years after the occurrence, whereas locoregional recurrence and new contralateral breast cancer are not usually fatal, the distant recurrence analysis is shown separately. Standard intention-to-treat log-rank analyses estimated first-event rate ratios (RR) and their confidence intervals (CIs).

FINDINGS

We obtained data from all four identified trials (ABCSG XII, SOFT, TEXT, and HOBOE trials), which included 7030 women with ER-positive tumours enrolled between June 17, 1999, and Aug 4, 2015. Median follow-up was 8·0 years (IQR 6·1-9·3). The rate of breast cancer recurrence was lower for women allocated to an aromatase inhibitor than for women assigned to tamoxifen (RR 0·79, 95% CI 0·69-0·90, p=0·0005). The main benefit was seen in years 0-4 (RR 0·68, 99% CI 0·55-0·85; p<0·0001), the period when treatments differed, with a 3·2% (95% CI 1·8-4·5) absolute reduction in 5-year recurrence risk (6·9% vs 10·1%). There was no further benefit, or loss of benefit, in years 5-9 (RR 0·98, 99% CI 0·73-1·33, p=0·89) or beyond year 10. Distant recurrence was reduced with aromatase inhibitor (RR 0·83, 95% CI 0·71-0·97; p=0·018). No significant differences were observed between treatments for breast cancer mortality (RR 1·01, 95% CI 0·82-1·24; p=0·94), death without recurrence (1·30, 0·75-2·25; p=0·34), or all-cause mortality (1·04, 0·86-1·27; p=0·68). There were more bone fractures with aromatase inhibitor than with tamoxifen (227 [6·4%] of 3528 women allocated to an aromatase inhibitor vs 180 [5·1%] of 3502 women allocated to tamoxifen; RR 1·27 [95% CI 1·04-1·54]; p=0·017). Non-breast cancer deaths (30 [0·9%] vs 24 [0·7%]; 1·30 [0·75-2·25]; p=0·36) and endometrial cancer (seven [0·2%] vs 15 [0·3%]; 0·52 [0·22-1·23]; p=0·14) were rare.

INTERPRETATION

Using an aromatase inhibitor rather than tamoxifen in premenopausal women receiving ovarian suppression reduces the risk of breast cancer recurrence. Longer follow-up is needed to assess any impact on breast cancer mortality.

FUNDING

Cancer Research UK, UK Medical Research Council.

Abstract P2-13-06: Clinical implication of HER2 status change after neoadjuvant chemotherapy with Trastuzumab and Pertuzumab (HP) in patients with HER2-positive breast cancer

Background: Patients with early HER2-positive breast cancer (BC) and residual disease after HER2-targeted neoadjuvant chemotherapy (NAC) are at high risk of recurrence. It is estimated that 10-30% of HER2-positive breast cancers change HER2 status after trastuzumab alone, but the effects of adding pertuzumab on this phenomenon and clinical outcomes remain unclear. We previously reported a high rate (~50%) of HER2 status change after HP in a small subset of patients. Herein, we present an updated analysis incorporating pathological review of additional cases.Methods: We identified patients with HER2-positive BC who received NAC with pertuzumab and trastuzumab (NAC-HP) followed by surgery at our institution between September 1, 2013 to November 1, 2019. Patients with HER2 status performed either at MSKCC or outside institutions were included. Change in HER2 status on residual disease from baseline was evaluated. We defined HER2 positivity as immunohistochemistry (IHC) IHC3+ or IHC0-2+ FISH amplified (ratio ≥ 2 or ratio &lt; 2 and HER2 copy number ≥ 6 signals/cell). HER2-low was defined as IHC 1+ or 2+, FISH non-amplified. Disease free survival (DFS) and overall survival (OS) were analyzed using the Kaplan-Meier method. Differences between patients with concordant and discordance HER2 status were assessed using the log-rank test.Results: Of 525 patients receiving NAC with HP, 229 (44%) patients had residual disease post NAC-HP. Among these 229 patients, 141 had both pre and post NAC-HP HER2 status available and were included in this analysis. HER2 status on biopsy specimens was determined at MSKCC in 35/141 (25%) and at external institution in 106/141 (75%). The majority of patients (84%) received dose-dense AC-THP; the remainder received TCHP or other HP-based regimens. Most (96%) of patients continued HP after surgery, and 2 patients received T-DM1. Of the 141 patients, 84/141(60%) were found to be HER2 concordant, while 57 (40%) were found to be HER2 discordant. In 13/57 (23%) patients, HER2 expression was lost (IHC 0), while in 44/57 (77%) patients, HER2-low profile was detected (IHC 1+ in 31, and IHC 2+, FISH non-amplified in 13). Further details are reported in the table. Patients with HER2 discordance after NAC-HP had similar survival outcome compared with patients who remained HER2 concordant (5-years DFS: 92.3% versus 88.7%, p=0.49 and 5-yr OS 93.6% versus 88.4%, p=0.70).Conclusions: In a single center cohort, discordant HER2 status after NAC-HP appeared frequently without statistically significant impact on survival outcome, although this finding may be due to the small size and hence low statistical power. Of these, HER2-low profile is the most frequent post treatment HER2 status change. This raises the possibility that patients with change in HER2 status may have heterogenous expression of HER2 at baseline, and HER2-loss or low sub-clones survive as residual disease due to the selection pressure of HP. Alternatively, anti-HER2 therapy may suppress HER2 expression in surviving cells. These findings could inform studies of tailored approaches in the post-neoadjuvant setting based on the biological profile of residual disease.

Pre NAC-HP HER2 statusNPost NAC-HP HER2 statusNDiscordantN=57IHC 3+: 19IHC0: 4IHC1+: 9IHC2+ FISH not ampl: 6IHC 0-2+ FISH ampl: 38IHC0: 9IHC1+: 22IHC2+ FISH not ampl: 7Concordant N= 84IHC 3+: 59IHC 3+: 47IHC 0- 2+ FISH ampl: 12IHC 0-2+ FISH ampl: 25IHC 3+: 4IHC 0- 2+ FISH ampl: 21

Citation Format: Emanuela Ferraro, Anton Safonov, Hanna Y Wen, Edi Brogi, Mithat Gonan, Andrea V. Barrio, Pedram Razavi, Sarat Chandarlapaty, Shanu Modi, Andrew D. Seidman, Larry Norton, Mark E. Robson, Chau T. Dang. Clinical implication of HER2 status change after neoadjuvant chemotherapy with Trastuzumab and Pertuzumab (HP) in patients with HER2-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 P2-13-06.

Abstract GS4-08: Comprehensive genomic profiling of patients with breast cancer identifies germline-somatic interactions mediating therapy resistance

Background: Germline genetic alterations are established mediators of breast carcinogenesis, often giving rise to specific forms of genomic instability. BRCA1/2 pathogenic variants (PVs) are emblematic of this phenomenon through their induction of homologous recombination deficiency. While specific patterns of genomic instability may sensitize cancers to therapies such as PARP inhibitors (PARPi) or platinum chemotherapy, their implications for lineage-directed therapies such as endocrine therapy (ET) or CDK4/6 inhibitors (CDK4/6i) are unknown. Herein, we systematically investigated the patterns of association of germline alterations with specific somatic alterations and explored the resulting effect on clinical outcomes. Methods: Patients who underwent germline and matched tumor tissue sequencing utilizing MSK-IMPACT from April 2014 to May 2021 and had available germline analysis results were included. The final analysis presented at SABCS will include 6000 tumors from 5,150 patients, anonymized according to established institutional IRB guidelines to allow for germline analysis on the full cohort. We analyzed genomic data to inform the full spectrum of somatic and germline mutations, ploidy, and allele-specific copy number to determine loss of heterozygosity (LOH). We performed gene- and pathway-level enrichment analyses between somatic variants and germline PVs. Univariable and multivariable Cox proportional hazards models were constructed to assess the association of therapy-specific progression-free survival (PFS) with select germline PVs and germline-somatic interactions. Results: The preliminary analysis includes 2,798 tumors from 2,242 patients with germline and somatic sequencing results. The most frequent germline PVs were: BRCA2 (n = 81), BRCA1 (n = 67), CHEK2 (n = 57), ATM (n = 32), PALB2 (n = 19). The cohort robustly confirmed previously established relationships such as mutual exclusivity of gATM and TP53 variants (OR 0.10, 95% CI 0.032 - 0.33, q = 0.005). Alterations of TP53 were seen in 83% (56/67) of gBRCA1 patients; however, this did not achieve significance when adjusted for receptor subtype (OR 3.90, 95% CI 1.34-11.38, q = 0.15). The size of the cohort allowed discovery of several novel relationships. For instance, gBRCA2 loss was associated with alterations in TGF-B pathway components (OR 3.58, 95% CI 1.70 - 7.56, q = 0.002), potentially relevant to metastatic disease progression. PIK3CA mutations were significantly less prevalent in both gBRCA2 (OR 0.52, 95% CI 0.31 - 0.87, q = 0.063) and gBRCA1 PVs (OR 0.21, 95% CI 0.085 - 0.51, q = 0.014). Our analysis uncovered a strong association between gBRCA2 and somatic RB1 pathogenic alterations (OR 3.58, 95% CI 1.70 - 7.56, q = 0.011), with most variants (80%) encountered in metastatic gBRCA2 tumors. Given the essential role of RB1 in CDK4/6i response, we investigated the effect of BRCA2 status on clinical efficacy of CDK4/6i-ET. Strikingly, gBRCA2 PVs were significantly associated with inferior PFS (HR 2.17, 95% CI 1.46-3.22, p &lt; 0.001) on first line treatment with CDK4/6i-ET. We posited the enrichment of somatic RB1 loss as a potential mechanism of resistance to CDK4/6i. Given the proximity of RB1 to BRCA2 on chromosome 13, we hypothesized that co-LOH of BRCA2 and RB1 predisposes the cancer cells to bi-allelic loss under therapeutic pressure of CDK4/6i. Indeed, 18/26 gBRCA2 (69.2%) tumors evaluable for allele-specific copy number had evidence of RB1 LOH. Discussion: Analysis of germline-somatic interactions yielded novel associations relevant to breast cancer progression and treatment resistance. Among these, we demonstrated BRCA2 carriers to have inferior outcomes to first line CDK4/6i-ET with potential implications for optimal first line therapy and sequencing of CDK4/6i vs PARPi in this patient population.

Citation Format: Anton Safonov, Chai Bandlamudi, Paulino Tallón de Lara, Emanuela Ferraro, Fatemeh Derakhshan, Marie Will, Mark Donoghue, Pier Selenica, Joshua Drago, Ezra Rosen, Carlos dos Anjos, Elaine Walsh, Elizabeth A Comen, Mehnaj Ahmed, Barbara Acevedo, Ahmet Zehir, Michael F Berger, David Solit, Larry Norton, Ronglai Shen, Zsofia Stadler, Simon Powell, Jorge S Reis-Filho, Sarat Chandarlapaty, Mark Robson, Pedram Razavi. Comprehensive genomic profiling of patients with breast cancer identifies germline-somatic interactions mediating therapy resistance [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 GS4-08.

Abstract P4-08-01: Effectiveness of electroacupuncture versus auricular acupuncture in breast cancer survivors with chronic musculoskeletal pain: The PEACE randomized clinical trial

Introduction: Chronic musculoskeletal pain is common and debilitating among breast cancer survivors. Recently, the Personalized Electroacupuncture (EA) versus Auricular Acupuncture (AA) Comparative Effectiveness (PEACE) trial demonstrated that both acupuncture methods improved pain control better than usual care (UC) in cancer survivors. However, the comparative effectiveness between EA and AA among breast cancer survivors, specifically, for chronic musculoskeletal pain is unknown. Here, we report the results of breast cancer survivors enrolled in the PEACE trial. Methods: PEACE is a three-arm, parallel, single center randomized trial investigating the effectiveness of EA and AA versus UC for chronic musculoskeletal pain in 360 cancer survivors. Patients in both EA and AA received ten weekly treatments. Patients in UC could receive ten EA treatments after week 12. The primary endpoint was the change in mean Brief Pain Inventory (BPI) pain intensity from baseline to week 12; change from baseline to week 24 was a secondary endpoint. We analyzed the subset of trial participants with a primary diagnosis of breast cancer (46%). We conducted constrained linear mixed model analyses, which constrained all arms to have a common pre-randomization baseline mean. Model-based mean estimates at weeks 12 and 24 were compared between arms using model contrasts. Results: Among the 165 breast cancer survivors, mean (SD) age was 60.3 (11.0) years, 35.8% were non-white, and mean time since cancer diagnosis was 5.4 (6.5) years. Patients had been experiencing pain for 5.6 (7.3) years, with baseline mean pain severity of 5.35 (95% CI: 5.04, 5.66). 86.7% had a prior history of surgery, 43.0% chemotherapy, 64.8% radiotherapy, and 50.3% endocrine therapy. The common locations of pain were lower back (24.2%), knee/leg (23.6%), and shoulder/arm/elbow (13.9%). 107 (66.9%) patients were taking pain medication. At week 12, the BPI pain severity score was 2.69 (2.26. 3.13) in EA, 3.60 (3.17, 4.02) in AA, and 5.06 (4.47, 5.65) in UC. The change in mean BPI intensity score from baseline was -2.65 (-3.06, -2.25), -1.75 (-2.15, -1.35), and -0.29 (-0.86, 0.28) in EA, AA, and UC, respectively (Table 1). At week 24, the mean BPI pain severity was 2.84 (95% Confidence Interval [CI]: 2.40, 3.28) in EA and 3.67 (95% CI: 3.23, 4.10) in AA. EA reduced pain severity significantly more than AA at both week 12, (-0.90 [-1.45, -0.36], p =0.001) and week 24 (-0.82, [-1.38, -0.27], p=0.004). Minimal toxicities were reported. Conclusions: While both EA and AA were associated with clinically meaningful and persistent reduction of pain among breast cancer survivors, EA was more effective than AA at reducing pain severity. Breast cancer survivors with chronic musculoskeletal pain may consider EA.

Table 1.Changes in BPI Pain Intensity from BaselineBPI Pain IntensityUCEAAAEA vs AAChange from baselineChange from baselineDifference from UCChange from baselineDifference from UCDifference between EA and AAWeek 12Mean (95% CI)-0.29 (-0.86, 0.28)-2.65* (-3.06, -2.25)-2.37*(-3.05, -1.68)-1.75* (-2.15, -1.35)-1.46* (-2.14, -0.78)-0.90* (-1.45, -0.36)*p≤0.001

Citation Format: Wanqing Iris Zhi, Jun J Mao, Raymond E Baser, Susan Q Li, Vicotria S Blinder, Larry Norton, Andrew D Seidman, Mark E Robson, Ting Bao. Effectiveness of electroacupuncture versus auricular acupuncture in breast cancer survivors with chronic musculoskeletal pain: The PEACE randomized clinical trial [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 P4-08-01.

Abstract GS3-03: Genomic analysis of 733 HER2+ breast cancers identifies recurrent pathways alterations associated with anti-HER2 resistance and new therapeutic vulnerabilities

Background:The introduction of anti-HER2 therapies, trastuzumab and pertuzumab (HP) to the treatment of metastatic HER2-positive breast cancer has had a transformational impact on the outcomes for this disease. Nevertheless, disease progression is ultimately observed in most patients within 3 years carrying the potential for morbidity and potentially more toxic therapies. To identify selective strategies to prevent disease progression, we sought to elucidate mechanisms of resistance to anti-HER2 therapies by analyzing a large cohort of genomically and clinically annotated HER2+ breast cancers. Methods: Patients with advanced HER2+ breast cancer who underwent prospective clinical tumor sequencing utilizing MSK-IMPACT assay between April 2014 and February 2021 were included in the analysis. Clinical HER2 positivity was defined as per ASCO/CAP guidelines. Cox proportional hazard models were used to determine the association between genomic alterations and progression-free survival (PFS) on 1st line HP and taxane-based therapy (THP). Only patients with a sequenced pre-treatment tumor sample were included in the survival analysis. Recurrent mutations identified were modeled in HER2+ breast cancer cell lines using short hairpin RNAs and CRISPR/Cas9, and the sensitivity of these isogenic pairs to HER2-targeted therapies was evaluated via metabolic and colony formation assays of cell proliferation. Results: We identified 733 ERBB2-amplified primary (n=385) and metastatic (n=348) that underwent sequencing. Concurrent PIK3CA mutations were identified in 30% of the tumors. Pathogenic activating alterations involving the MAPK pathway were observed in 12.8% of tumors with the most frequent alterations being NF1 loss, ERBB2 and RAS activating mutations. MAPK alterations were significantly enriched in the metastatic tumors (16.6%) compared to the treatment-naïve primaries (9.8%, p=0.020). The outcome analysis included 145 patients with advanced clinically HER2+ breast cancer whose tumors were sequenced prior to starting 1st line THP. Twenty percent (29/145) of tumors did not show genomic ERBB2 amplification as detected by NGS and had a significantly worse outcome (median PFS of 9.4 months [95% CI 5.5-19] and 23 months [95% CI 17-30], respectively; p=0.015). PIK3CA mutations were also associated with a shorter PFS (mutant: 13 months [95%CI: 7.7-18] vs wild type: 23 months [95%CI 17-16], p=0.0013). We further found reduced PFS in MAPK altered tumors (median PFS 9.9 months; 95% CI: 5.5-17) compared to the rest of the population (median PFS 21 months; 95% CI: 17-30; p=0.01). On multivariable analysis adjusted for estrogen receptor status, and presence of PIK3CA/AKT1/PTEN mutations and genomic ERBB2 amplification, MAPK pathway alterations were independently associated with worse outcome (HR: 2.25; 95% CI: 1.29, 3.93; multivariate p = 0.0043). To establish a causal role for MAPK alterations in reducing efficacy of anti-HER2 therapy, we depleted NF1 expression or expressed mutant KRAS or BRAF in a panel of HER2+ breast cancer cell lines. Consistently, MAPK-altered cell lines exhibited resistance to FDA approved HER2 inhibitors in vitro and in vivo. Conclusions: This clinicogenomic analysis of mechanisms of resistance to anti-HER2 therapy demonstrated that PIK3CA activating mutations and lack of genomic ERBB2 amplification as detected by tumor sequencing are associated with shortened PFS on HP-based therapy. Our analysis uniquely identified MAPK pathway alterations as additional potential drivers of resistance to anti-HER2 therapy. Inhibition of the PI3K or MAPK pathway in such tumors may represent a new therapeutic strategy to extend H/P benefit.

Citation Format: Emanuela Ferraro, Alison Smith, Anton Safonov, Paulino Tallon De Lara, Cristina Bernado', Enrique J. Arenas Lahuerta, Joaquín Arribas, David Solit, Jorge S. Reis-Filho, Neal Rosen, Larry Norton, Shanu Modi, Mark E. Robson, Chau T. Dang, Giuseppe Curigliano, Sarat Chandarlapaty, Pedram Razavi. Genomic analysis of 733 HER2+ breast cancers identifies recurrent pathways alterations associated with anti-HER2 resistance and new therapeutic vulnerabilities [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 GS3-03.

Mobile mammography in New York City: analysis of 32,350 women utilizing a screening mammogram program

Mobile mammography vans (mammovans) may help close the gap to access of breast cancer screening by providing resources to underserved communities. Minimal data exists on the populations served, the ability of mammovans to reach underserved populations, and the outcomes of participants. We sought to determine the demographic characteristics, number of breast cancers diagnosed, and number of women who used the American Italian Cancer Foundation (AICF) Mobile, No-Cost Breast Cancer Screening Program within the five boroughs of New York City. Data were collected by the AICF from 2014 to 2019 on a voluntary basis from participants at each screening location. Women aged 40 to 79 years who had not had a mammogram in the previous 12 months were invited to participate. Each participant underwent a clinical breast exam by a nurse practitioner followed by a screening mammogram. Images were read by a board-certified radiologist contracted by the AICF from Multi Diagnostic Services. There were 32,350 participants in this study. Sixty-three percent reported an annual household income ≤$25,000, and 30% did not have health insurance. More than half of participants identified as either African American (28%) or Hispanic (27%). Additional testing was performed for 5359 women found to have abnormal results on screening. In total, 68 cases of breast cancer were detected. Breast cancer disparities are multifactorial, with the greatest factor being limited access to care. Mobile, no-cost mammogram screening programs show great promise in helping to close the gap to screening access.

Geometric network analysis provides prognostic information in patients with high grade serous carcinoma of the ovary treated with immune checkpoint inhibitors

Network analysis methods can potentially quantify cancer aberrations in gene networks without introducing fitted parameters or variable selection. A new network curvature-based method is introduced to provide an integrated measure of variability within cancer gene networks. The method is applied to high-grade serous ovarian cancers (HGSOCs) to predict response to immune checkpoint inhibitors (ICIs) and to rank key genes associated with prognosis. Copy number alterations (CNAs) from targeted and whole-exome sequencing data were extracted for HGSOC patients (n = 45) treated with ICIs. CNAs at a gene level were represented on a protein–protein interaction network to define patient-specific networks with a fixed topology. A version of Ollivier–Ricci curvature was used to identify genes that play a potentially key role in response to immunotherapy and further to stratify patients at high risk of mortality. Overall survival (OS) was defined as the time from the start of ICI treatment to either death or last follow-up. Kaplan–Meier analysis with log-rank test was performed to assess OS between the high and low curvature classified groups. The network curvature analysis stratified patients at high risk of mortality with p = 0.00047 in Kaplan–Meier analysis in HGSOC patients receiving ICI. Genes with high curvature were in accordance with CNAs relevant to ovarian cancer. Network curvature using CNAs has the potential to be a novel predictor for OS in HGSOC patients treated with immunotherapy.

Clonal hematopoiesis is associated with risk of severe Covid-19

Acquired somatic mutations in hematopoietic stem and progenitor cells (clonal hematopoiesis or CH) are associated with advanced age, increased risk of cardiovascular and malignant diseases, and decreased overall survival. These adverse sequelae may be mediated by altered inflammatory profiles observed in patients with CH. A pro-inflammatory immunologic profile is also associated with worse outcomes of certain infections, including SARS-CoV-2 and its associated disease Covid-19. Whether CH predisposes to severe Covid-19 or other infections is unknown. Among 525 individuals with Covid-19 from Memorial Sloan Kettering (MSK) and the Korean Clonal Hematopoiesis (KoCH) consortia, we show that CH is associated with severe Covid-19 outcomes (OR = 1.85, 95%=1.15-2.99, p = 0.01), in particular CH characterized by non-cancer driver mutations (OR = 2.01, 95% CI = 1.15-3.50, p = 0.01). We further explore the relationship between CH and risk of other infections in 14,211 solid tumor patients at MSK. CH is significantly associated with risk of Clostridium Difficile (HR = 2.01, 95% CI: 1.22-3.30, p = 6×10-3) and Streptococcus/Enterococcus infections (HR = 1.56, 95% CI = 1.15-2.13, p = 5×10-3). These findings suggest a relationship between CH and risk of severe infections that warrants further investigation.

The impact of scaling up access to treatment and imaging modalities on global disparities in breast cancer survival: a simulation-based analysis

BACKGROUND

Female breast cancer is the most commonly diagnosed cancer in the world, with wide variations in reported survival by country. Women in low-income and middle-income countries (LMICs) in particular face several barriers to breast cancer services, including diagnostics and treatment. We aimed to estimate the potential impact of scaling up the availability of treatment and imaging modalities on breast cancer survival globally, together with improvements in quality of care.

METHODS

For this simulation-based analysis, we used a microsimulation model of global cancer survival, which accounts for the availability and stage-specific survival impact of specific treatment modalities (chemotherapy, radiotherapy, surgery, and targeted therapy), imaging modalities (ultrasound, x-ray, CT, MRI, PET, and single-photon emission computed tomography [SPECT]), and quality of cancer care, to simulate 5-year net survival for women with newly diagnosed breast cancer in 200 countries and territories in 2018. We calibrated the model to empirical data on 5-year net breast cancer survival in 2010-14 from CONCORD-3. We evaluated the potential impact of scaling up specific imaging and treatment modalities and quality of care to the mean level of high-income countries, individually and in combination. We ran 1000 simulations for each policy intervention and report the means and 95% uncertainty intervals (UIs) for all model outcomes.

FINDINGS

We estimate that global 5-year net survival for women diagnosed with breast cancer in 2018 was 67·9% (95% UI 62·9-73·4) overall, with an almost 25-times difference between low-income (3·5% [0·4-10·0]) and high-income (87·0% [85·6-88·4]) countries. Among individual treatment modalities, scaling up access to surgery alone was estimated to yield the largest survival gains globally (2·7% [95% UI 0·4-8·3]), and scaling up CT alone would have the largest global impact among imaging modalities (0·5% [0·0-2·0]). Scaling up a package of traditional modalities (surgery, chemotherapy, radiotherapy, ultrasound, and x-ray) could improve global 5-year net survival to 75·6% (95% UI 70·6-79·4), with survival in low-income countries improving from 3·5% (0·4-10·0) to 28·6% (4·9-60·1). Adding concurrent improvements in quality of care could further improve global 5-year net survival to 78·2% (95% UI 74·9-80·4), with a substantial impact in low-income countries, improving net survival to 55·3% (42·2-67·8). Comprehensive scale-up of access to all modalities and improvements in quality of care could improve global 5-year net survival to 82·3% (95% UI 79·3-85·0).

INTERPRETATION

Comprehensive scale-up of treatment and imaging modalities, and improvements in quality of care could improve global 5-year net breast cancer survival by nearly 15 percentage points. Scale-up of traditional modalities and quality-of-care improvements could achieve 70% of these total potential gains, with substantial impact in LMICs, providing a more feasible pathway to improving breast cancer survival in these settings even without the benefits of future investments in targeted therapy and advanced imaging.

FUNDING

Harvard T H Chan School of Public Health, and National Cancer Institute P30 Cancer Center Support Grant to Memorial Sloan Kettering Cancer Center.

Trastuzumab for early-stage, HER2-positive breast cancer: a meta-analysis of 13 864 women in seven randomised trials

BACKGROUND

Trastuzumab targets the extracellular domain of the HER2 protein. Adding trastuzumab to chemotherapy for patients with early-stage, HER2-positive breast cancer reduces the risk of recurrence and death, but is associated with cardiac toxicity. We investigated the long-term benefits and risks of adjuvant trastuzumab on breast cancer recurrence and cause-specific mortality.

METHODS

We did a collaborative meta-analysis of individual patient data from randomised trials assessing chemotherapy plus trastuzumab versus the same chemotherapy alone. Randomised trials that enrolled women with node-negative or node-positive, operable breast cancer were included. We collected individual patient-level data on baseline characteristics, dates and sites of first distant breast cancer recurrence and any previous local recurrence or second primary cancer, and the date and underlying cause of death. Primary outcomes were breast cancer recurrence, breast cancer mortality, death without recurrence, and all-cause mortality. Standard intention-to-treat log-rank analyses, stratified by age, nodal status, oestrogen receptor (ER) status, and trial yielded first-event rate ratios (RRs).

FINDINGS

Seven randomised trials met the inclusion criteria, and included 13 864 patients enrolled between February, 2000, and December, 2005. Mean scheduled treatment duration was 14·4 months and median follow-up was 10·7 years (IQR 9·5 to 11·9). The risks of breast cancer recurrence (RR 0·66, 95% CI 0·62 to 0·71; p<0·0001) and death from breast cancer (0·67, 0·61 to 0·73; p<0·0001) were lower with trastuzumab plus chemotherapy than with chemotherapy alone. Absolute 10-year recurrence risk was reduced by 9·0% (95% CI 7·4 to 10·7; p<0·0001) and 10-year breast cancer mortality was reduced by 6·4% (4·9 to 7·8; p<0·0001), with a 6·5% reduction (5·0 to 8·0; p<0·0001) in all-cause mortality, and no increase in death without recurrence (0·4%, -0·3 to 1·1; p=0·35). The proportional reduction in recurrence was largest in years 0-1 after randomisation (0·53, 99% CI 0·46 to 0·61), with benefits persisting through years 2-4 (0·73, 0·62 to 0·85) and 5-9 (0·80, 0·64 to 1·01), and little follow-up beyond year 10. Proportional recurrence reductions were similar irrespective of recorded patient and tumour characteristics, including ER status. The more high risk the tumour, the larger the absolute reductions in 5-year recurrence (eg, 5·7% [95% CI 3·1 to 8·3], 6·8% [4·7 to 9·0], and 10·7% [7·7 to 13·6] in N0, N1-3, and N4+ disease).

INTERPRETATION

Adding trastuzumab to chemotherapy for early-stage, HER2-positive breast cancer reduces recurrence of, and mortality from, breast cancer by a third, with worthwhile proportional reductions irrespective of recorded patient and tumour characteristics.

FUNDING

Cancer Research UK, UK Medical Research Council.

Poor response to neoadjuvant chemotherapy in metaplastic breast carcinoma

Metaplastic breast carcinoma (MpBC) is a rare special histologic subtype of breast carcinoma characterized by the presence of squamous and/or mesenchymal differentiation. Most MpBCs are of triple-negative phenotype and neoadjuvant chemotherapy (NAC) is frequently utilized in patients with MpBC. The aim of this study was to evaluate response to NAC in a retrospective cohort of MpBCs. We identified 44 patients with MpBC treated with NAC at our center between 2002 and 2018. Median age was 48 years, 86% were clinical stage II-III, and 36% were clinically node-positive. Most (80%) MpBCs were triple-negative or low (1-10%) hormonal receptor positive and HER2 negative on pre-NAC biopsy. While on NAC, 49% showed no clinical response or clinico-radiological progression. Matrix-producing subtype was associated with clinico-radiological response (p = 0.0036). Post NAC, two patients initially ineligible for breast-conserving surgery (BCS) were downstaged to be eligible for BCS, whereas three patients potentially eligible for BCS before treatment became ineligible due to disease progression. Only one (2%) patient had a pathologic complete response (pCR). Among the 16 patients presenting with biopsy-proven clinical node-positive disease, 3 (19%) had nodal pCR. Axillary lymph node dissection was avoided in 3 (19%) patients who had successful axillary downstaging. Residual cancer burden (RCB) was assessed in 22 patients and was significantly associated with disease-free survival and overall survival. We observed a poor response or even disease progression on NAC among patients with MpBC, suggesting that NAC should be reserved for patients with inoperable MpBC.

Anti-tumor effects of an ID antagonist with no observed acquired resistance

ID proteins are helix-loop-helix (HLH) transcriptional regulators frequently overexpressed in cancer. ID proteins inhibit basic-HLH transcription factors often blocking differentiation and sustaining proliferation. A small-molecule, AGX51, targets ID proteins for degradation and impairs ocular neovascularization in mouse models. Here we show that AGX51 treatment of cancer cell lines impairs cell growth and viability that results from an increase in reactive oxygen species (ROS) production upon ID degradation. In mouse models, AGX51 treatment suppresses breast cancer colonization in the lung, regresses the growth of paclitaxel-resistant breast tumors when combined with paclitaxel and reduces tumor burden in sporadic colorectal neoplasia. Furthermore, in cells and mice, we fail to observe acquired resistance to AGX51 likely the result of the inability to mutate the binding pocket without loss of ID function and efficient degradation of the ID proteins. Thus, AGX51 is a first-in-class compound that antagonizes ID proteins, shows strong anti-tumor effects and may be further developed for the management of multiple cancers.

Change in HER2 status after neoadjuvant chemotherapy (NAC) with trastuzumab and pertuzumab (HP) in patients with HER2-positive early-stage breast cancer

e12614

Background: Combination of HP with NAC in the neoadjuvant setting leads to an high rate of pathological complete response (pCR) in patients with stage II-III HER2+ breast cancer (BC). The rate of change in HER2-status after NAC reported in literature is between 10-30%, although NAC comprises a various regimens, and the clinical significance of this phenomenon is unclear. Methods: We extracted data on patients with HER2+ BC treated with NAC and HP between September 1, 2013 to November 1, 2019. Only patients with internally verified HER2 status at our center were enrolled. The rate of pCR (ypT0/is ypN0) and the change in HER2 status on residual disease from baseline were evaluated. We used standard definition of HER2 status based on ASCO/CAP guidelines 2018. HER2-low was defined as immunohistochemistry (IHC) 1+ or 2+, FISH non-amplified. Results: Overall, 130 pts were identified. All patients received dose-dense AC-THP, except for 13 patients who received TCHP or other HP-based regimens. The pCR was achieved in 77/130 (59%) of patients and 53/130 (41%) had residual disease. Among 53 patients with residual disease, HER2 status was analyzed in 25 patients and was pending on the remaining patients. In the 25 analyzed patients, 13 had HER2-loss in residual disease. In 4/13 patients, HER2 expression was lost (IHC 0); in 9/13 patients, HER2-low profile was found (IHC 1+ in 6 patients, and IHC 2+, FISH non-amplified in 3). Details on HER2 status change are described in the table below. Conversely, 12/25 had concordant HER2 status after NAC. Conclusions: At single center, the change in HER2 status after NAC with HP appeared frequent. Pathological review of additional cases is ongoing. The clinical significance is still unclear but may open the possibility to investigate tailored approach in post-neoadjuvant setting based on the biological profile of residual disease. [Table: see text]

TERT promoter hotspot mutations and gene amplification in metaplastic breast cancer

Metaplastic breast cancers (MBCs) are characterized by complex genomes, which seem to vary according to their histologic subtype. TERT promoter hotspot mutations and gene amplification are rare in common forms of breast cancer, but present in a subset of phyllodes tumors. Here, we sought to determine the frequency of genetic alterations affecting TERT in a cohort of 60 MBCs with distinct predominant metaplastic components (squamous, 23%; spindle, 27%; osseous, 8%; chondroid, 42%), and to compare the repertoire of genetic alterations of MBCs according to the presence of TERT promoter hotspot mutations or gene amplification. Forty-four MBCs were subjected to: whole-exome sequencing (WES; n = 27) or targeted sequencing of 341-468 cancer-related genes (n = 17); 16 MBCs were subjected to Sanger sequencing of the TERT promoter, TP53 and selected exons of PIK3CA, HRAS, and BRAF. TERT promoter hotspot mutations (n = 9) and TERT gene amplification (n = 1) were found in 10 of the 60 MBCs analyzed, respectively. These TERT alterations were less frequently found in MBCs with predominant chondroid differentiation than in other MBC subtypes (p = 0.01, Fisher's exact test) and were mutually exclusive with TP53 mutations (p < 0.001, CoMEt). In addition, a comparative analysis of the MBCs subjected to WES or targeted cancer gene sequencing (n = 44) revealed that MBCs harboring TERT promoter hotspot mutations or gene amplification (n = 6) more frequently harbored PIK3CA than TERT wild-type MBCs (n = 38; p = 0.001; Fisher's exact test). In conclusion, TERT somatic genetic alterations are found in a subset of TP53 wild-type MBCs with squamous/spindle differentiation, highlighting the genetic diversity of these cancers.

The genetic landscape of metaplastic breast cancers and uterine carcinosarcomas

Metaplastic breast carcinoma (MBC) and uterine carcinosarcoma (UCS) are rare aggressive cancers, characterized by an admixture of adenocarcinoma and areas displaying mesenchymal/sarcomatoid differentiation. We sought to define whether MBCs and UCSs harbor similar patterns of genetic alterations, and whether the different histologic components of MBCs and UCSs are clonally related. Whole-exome sequencing (WES) data from MBCs (n = 35) and UCSs (n = 57, The Cancer Genome Atlas) were reanalyzed to define somatic genetic alterations, altered signaling pathways, mutational signatures, and genomic features of homologous recombination DNA repair deficiency (HRD). In addition, the carcinomatous and sarcomatous components of an additional cohort of MBCs (n = 11) and UCSs (n = 6) were microdissected separately and subjected to WES, and their clonal relatedness was assessed. MBCs and UCSs harbored recurrent genetic alterations affecting TP53, PIK3CA, and PTEN, similar patterns of gene copy number alterations, and an enrichment in alterations affecting the epithelial-to-mesenchymal transition (EMT)-related Wnt and Notch signaling pathways. Differences were observed, however, including a significantly higher prevalence of FAT3 and FAT1 somatic mutations in MBCs compared to UCSs, and conversely, UCSs significantly more frequently harbored somatic mutations affecting FBXW7 and PPP2R1A as well as HER2 amplification than MBCs. Genomic features of HRD and biallelic alterations affecting bona fide HRD-related genes were found to be more prevalent in MBCs than in UCSs. The distinct histologic components of MBCs and UCSs were clonally related in all cases, with the sarcoma component likely stemming from a minor subclone of the carcinoma component in the samples with interpretable chronology of clonal evolution. Despite the similar histologic features and pathways affected by genetic alterations, UCSs differ from MBCs on the basis of FBXW7 and PPP2R1A mutations, HER2 amplification, and lack of HRD, supporting the notion that these entities are more than mere phenocopies of the same tumor type in different anatomical sites.

Accuracy of Magnetic Resonance Imaging-Guided Biopsy to Verify Breast Cancer Pathologic Complete Response After Neoadjuvant Chemotherapy: A Nonrandomized Controlled Trial

IMPORTANCE

After neoadjuvant chemotherapy (NAC), pathologic complete response (pCR) is an optimal outcome and a surrogate end point for improved disease-free and overall survival. To date, surgical resection remains the only reliable method for diagnosing pCR.

OBJECTIVE

To evaluate the accuracy of magnetic resonance imaging (MRI)-guided biopsy for diagnosing a pCR after NAC compared with reference-standard surgical resection.

DESIGN, SETTING, AND PARTICIPANTS

Single-arm, phase 1, nonrandomized controlled trial in a single tertiary care cancer center from September 26, 2017, to July 29, 2019. The median follow-up was 1.26 years (interquartile range, 0.85-1.59 years). Data analysis was performed in November 2019. Eligible patients had (1) stage IA to IIIC biopsy-proven operable invasive breast cancer; (2) standard-of-care NAC; (3) MRI before and after NAC, with imaging complete response defined as no residual enhancement on post-NAC MRI; and (4) definitive surgery. Patients were excluded if they were younger than 18 years, had a medical reason precluding study participation, or had a prior history of breast cancer.

INTERVENTIONS

Post-NAC MRI-guided biopsy without the use of intravenous contrast of the tumor bed before definitive surgery.

MAIN OUTCOMES AND MEASURES

The primary end point was the negative predictive value of MRI-guided biopsy, with true-negative defined as negative results of the biopsy (ie, no residual cancer) corresponding to a surgical pCR. Accuracy, sensitivity, positive predictive value, and specificity were also calculated. Two clinical definitions of pCR were independently evaluated: definition 1 was no residual invasive cancer; definition 2, no residual invasive or in situ cancer.

RESULTS

Twenty of 23 patients (87%) had evaluable data (median [interquartile range] age, 51.5 [39.0-57.5] years; 20 women [100%]; 13 White patients [65%]). Of the 20 patients, pre-NAC median tumor size on MRI was 3.0 cm (interquartile range, 2.0-5.0 cm). Nineteen of 20 patients (95%) had invasive ductal carcinoma; 15 of 20 (75%) had stage II cancer; 11 of 20 (55%) had ERBB2 (formerly HER2 or HER2/neu)-positive cancer; and 6 of 20 (30%) had triple-negative cancer. Surgical pathology demonstrated a pCR in 13 of 20 (65%) patients and no pCR in 7 of 20 patients (35%) when pCR definition 1 was used. Results of MRI-guided biopsy had a negative predictive value of 92.8% (95% CI, 66.2%-99.8%), with accuracy of 95% (95% CI, 75.1%-99.9%), sensitivity of 85.8% (95% CI, 42.0%-99.6%), positive predictive value of 100%, and specificity of 100% for pCR definition 1. Only 1 patient had a false-negative MRI-guided biopsy result (surgical pathology showed <0.02 cm of residual invasive cancer).

CONCLUSIONS AND RELEVANCE

This study's results suggest that the accuracy of MRI-guided biopsy to diagnose a post-NAC pCR approaches that of reference-standard surgical resection. MRI-guided biopsy may be a viable alternative to surgical resection for this population after NAC, which supports the need for further investigation.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03289195.

Road Map to Safe and Well-Designed De-escalation Trials of Systemic Adjuvant Therapy for Solid Tumors

An important challenge in the field of cancer is finding the balance between delivering effective treatments and avoiding adverse effects and financial toxicity caused by innovative, yet expensive, drugs. To address this, several treatment de-escalation trials have been conducted, but only a few of these have provided clear answers. A few trials had poor accrual or had design flaws that led to conflicting results. Members of the Breast International Group (BIG) and North American Breast Cancer Group (NABCG) believe the way forward is to understand the lessons from these trials and listen more carefully to what truly matters to our patients. We reviewed several adjuvant trials of different cancer types and developed a road map for improving the design and implementation of future de-escalation trials. The road map incorporates patients' insights obtained through focused group discussions across the BIG-NABCG networks. Considerations for the development of de-escalation trials for systemic adjuvant treatment, including noninferiority trial design, choice of end points, and prioritization of a patient's perspectives, are presented in this consensus article.