Genetic Alterations Detected by Circulating Tumor DNA in HER2-Low Metastatic Breast Cancer.

PURPOSE: About 50% of breast cancers are defined as HER2-low and may benefit from HER2-directed antibody-drug conjugates. While tissue sequencing has evaluated potential differences in genomic profiles for patients with HER2-low breast cancer, genetic alterations in circulating tumor DNA (ctDNA) have not been well described. EXPERIMENTAL DESIGN: We retrospectively analyzed 749 patients with metastatic breast cancer (MBC) and ctDNA evaluation by Guardant360 from three academic medical centers. Tumors were classified as HER2-low, HER2-0 (IHC 0) or HER2-positive. Single-nucleotide variants, copy-number variants, and oncogenic pathways were compared across the spectrum of HER2 expression. Overall survival (OS) was evaluated by HER2 status and according to oncogenic pathways. RESULTS: Patients with HER2-low had higher rates of PIK3CA mutations [relative risk ratio (RRR), 1.57; P = 0.024] compared with HER2-0 MBC. There were no differences in ERBB2 alterations or oncogenic pathways between HER2-low and HER2-0 MBC. Patients with HER2-positive MBC had more ERBB2 alterations (RRR, 12.43; P = 0.002 for amplification; RRR, 3.22; P = 0.047 for mutations, in the hormone receptor-positive cohort), fewer ERS1 mutations (RRR, 0.458; P = 0.029), and fewer ER pathway alterations (RRR, 0.321; P < 0.001). There was no difference in OS for HER2-low and HER2-0 MBC [HR, 1.01; 95% confidence interval (CI), 0.79-1.29], while OS was improved in HER2-positive MBC (HR, 0.32; 95% CI, 0.21-0.49; P < 0.001). CONCLUSIONS: We observed a higher rate of PIK3CA mutations, but no significant difference in ERBB2 alterations, oncogenic pathways, or prognosis, between patients with HER2-low and HER2-0 MBC. If validated, our findings support the conclusion that HER2-low MBC does not represent a unique biological subtype.

Targeted Treatment for High-Risk Early-Stage Triple-Negative Breast Cancer: Spotlight on Pembrolizumab.

Triple-negative breast cancer (TNBC) is a biologically aggressive yet heterogeneous disease that disproportionately affects younger women and women of color compared to other breast cancer subtypes. The paucity of effective targeted therapies and the prevalence of chemotherapeutic resistance in high-risk, early-stage TNBC pose significant clinical challenges. Deeper insights into the genomic and immune landscape have revealed key features of TNBC, including intrinsic genomic instability, DNA repair deficiency, and potentially an immunogenic tumor microenvironment. These advances led to landmark trials with immune checkpoint inhibitors in the advanced-stage setting, which subsequently translated into immunotherapy-based clinical trials in the early-stage setting and recent promising results. Pembrolizumab, an anti-programmed death 1 (PD-1) monoclonal antibody, was investigated in combination with platinum-, taxane- and anthracycline-based neoadjuvant chemotherapy followed by adjuvant pembrolizumab monotherapy for patients with high-risk, early-stage TNBC in the randomized, double-blind, placebo-controlled phase 3 KEYNOTE-522 trial. In July 2021, the US Food and Drug Administration (FDA) granted approval for pembrolizumab based on marked improvement in pathologic complete response rate and 3-year event-free survival compared to neoadjuvant chemotherapy alone. This advance immediately altered the longstanding treatment paradigm. Here, we review the impact of pembrolizumab plus chemotherapy for the treatment of patients with high-risk, early-stage TNBC, and discuss immunotherapy-related toxicity considerations, key immunomodulatory biomarkers under active investigation, and remaining clinical questions for future research directions.

Management of Diarrhea in Patients with HER2-Positive Breast Cancer Treated with Neratinib: A Case Series and Summary of the Literature.

INTRODUCTION: Neratinib and neratinib-based combinations have demonstrated efficacy for treatment of human epidermal growth factor receptor 2-positive (HER2+) early-stage and metastatic breast cancers. However, diarrhea has been reported as a common adverse event leading to neratinib discontinuation. Results from the CONTROL trial suggest that proactive diarrhea management with antidiarrheal prophylaxis or dose escalation of neratinib from a lower starting dose to the full FDA-approved dose of 240 mg/day can reduce the incidence, duration, and severity of neratinib-associated diarrhea in patients with early-stage breast cancer. Dose escalation has been included in the FDA-approved label for both early-stage and metastatic HER2+ breast cancer since June 2021. CASE SERIES: This series of five cases details real-world clinical implementation of strategies for management of neratinib-induced diarrhea in patients with early-stage and metastatic HER2+ breast cancer, including a patient with a pre-existing gastrointestinal disorder. MANAGEMENT AND OUTCOME: In four of five cases, diarrhea was managed with neratinib dose escalation, and antidiarrheal prophylaxis with loperamide plus colestipol was used in the remaining case. Management of diarrhea allowed all patients to remain on therapy. DISCUSSION: This case series shows that neratinib-associated diarrhea can be managed effectively with neratinib dose escalation from a lower initial starting dose and/or prophylactic antidiarrheal medications in a real-world clinical setting. The findings highlight the importance of patient-provider communication in proactive management of adverse events. Widespread implementation of the strategies described here may improve adherence and thereby clinical outcomes for patients with HER2+ breast cancer treated with neratinib.

Phase 1b trial of anti-VEGF/PDGFR vorolanib combined with immune checkpoint inhibitors in patients with advanced solid tumors.

PURPOSE: Vorolanib is a multi-target tyrosine kinase inhibitor with anti-angiogenic properties. This study aimed to evaluate the tolerability, safety and efficacy of vorolanib when added to checkpoint inhibitors (CPIs) in patients with advanced solid tumors. METHODS: We conducted a phase 1b study of vorolanib (300 or 400 mg orally once daily) plus pembrolizumab or nivolumab using a standard 3 + 3 design to determine the dose-limiting toxicity (DLT), maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). The endpoints included safety, toxicity and objective response rate, according to Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST 1.1). RESULTS: Sixteen patients (9 in pembrolizumab arm, 7 in nivolumab arm) with gastrointestinal or lung cancers were enrolled. All patients had at least 1 treatment-related adverse event (TRAE). The most common TRAEs across all cohorts were lymphopenia (n = 7), leukopenia (n = 5), fatigue (n = 5), and alanine aminotransferase elevation (n = 5); most toxicities were grade (G) 1-2. DLTs were reported in 3 patients at vorolanib 400 mg dose level, with G3 aspartate aminotransferase elevation, G3 rectal hemorrhage, and G3 rash. Of 13 total response-evaluable patients, 2 patients had confirmed partial responses (1 rectal squamous cell cancer and 1 small cell lung cancer). Two patients achieved prolonged stable disease. Vorolanib 300 mg daily was determined to be the RP2D for either pembrolizumab or nivolumab. CONCLUSION: Combination vorolanib 300 mg orally once daily plus CPI appears to be a feasible regimen with manageable toxicity and promising efficacy in select tumor types. NCT03511222. Date of Registration: April 18, 2018.

Circulating tumour DNA characterisation of invasive lobular carcinoma in patients with metastatic breast cancer.

BACKGROUND: Limited data exist to characterise molecular differences in circulating tumour DNA (ctDNA) for patients with invasive lobular carcinoma (ILC). We analysed metastatic breast cancer patients with ctDNA testing to assess genomic differences among patients with ILC, invasive ductal carcinoma (IDC), and mixed histology. METHODS: We retrospectively analysed 980 clinically annotated patients (121 ILC, 792 IDC, and 67 mixed histology) from three academic centers with ctDNA evaluation by Guardant360™. Single nucleotide variations (SNVs), copy number variations (CNVs), and oncogenic pathways were compared across histologies. FINDINGS: ILC was significantly associated with HR+ HER2 negative and HER2 low. SNVs were higher in patients with ILC compared to IDC or mixed histology (Mann Whitney U test, P < 0.05). In multivariable analysis, HR+ HER2 negative ILC was significantly associated with mutations in CDH1 (odds ratio (OR) 9.4, [95% CI 3.3-27.2]), ERBB2 (OR 3.6, [95% confidence interval (CI) 1.6-8.2]), and PTEN (OR 2.5, [95% CI 1.05-5.8]) genes. CDH1 mutations were not present in the mixed histology cohort. Mutations in the PI3K pathway genes (OR 1.76 95% CI [1.18-2.64]) were more common in patients with ILC. In an independent cohort of nearly 7000 metastatic breast cancer patients, CDH1 was significantly co-mutated with targetable alterations (PIK3CA, ERBB2) and mutations associated with endocrine resistance (ARID1A, NF1, RB1, ESR1, FGFR2) (Benjamini-Hochberg Procedure, all q < 0.05). INTERPRETATION: Evaluation of ctDNA revealed differences in pathogenic alterations and oncogenic pathways across breast cancer histologies with implications for histologic classification and precision medicine treatment. FUNDING: Lynn Sage Cancer Research Foundation, OncoSET Precision Medicine Program, and UL1TR001422.

Radiation-Induced Brachial Plexopathy in Patients With Breast Cancer Treated With Comprehensive Adjuvant Radiation Therapy.

PURPOSE: Our purpose was to describe the risk of radiation-induced brachial plexopathy (RIBP) in patients with breast cancer who received comprehensive adjuvant radiation therapy (RT). METHODS AND MATERIALS: Records for 498 patients who received comprehensive adjuvant RT (treatment of any residual breast tissue, the underlying chest wall, and regional nodes) between 2004 and 2012 were retrospectively reviewed. All patients were treated with conventional 3 to 5 field technique (CRT) until 2008, after which intensity modulated RT (IMRT) was introduced. RIBP events were determined by reviewing follow-up documentation from oncologic care providers. Patients with RIBP were matched (1:2) with a control group of patients who received CRT and a group of patients who received IMRT. Dosimetric analyses were performed in these patients to determine whether there were differences in ipsilateral brachial plexus dose distribution between RIBP and control groups. RESULTS: Median study follow-up was 88 months for the overall cohort and 92 months for the IMRT cohort. RIBP occurred in 4 CRT patients (1.6%) and 1 IMRT patient (0.4%) (P = .20). All patients with RIBP in the CRT cohort received a posterior axillary boost. Maximum dose to the brachial plexus in RIBP, CRT control, and IMRT control patients had median values of 56.0 Gy (range, 49.7-65.1), 54.8 Gy (47.4-60.5), and 54.8 Gy (54.2-57.3), respectively. CONCLUSIONS: RIBP remains a rare complication of comprehensive adjuvant breast radiation and no clear dosimetric predictors for RIBP were identified in this study. The IMRT technique does not appear to adversely affect the development of this late toxicity.

Age-related disparities in older women with breast cancer.

Improvements in breast cancer (BC) mortality rates have not been seen in the older adult community, and the fact that older adults are more likely to die from their cancer than younger women establishes a major health disparity. Studies have identified that despite typically presenting with more favorable histology, older women present with more advanced disease, which may be related in part to delayed diagnosis. This is supported by examination of screening practices in older adults. Older women have a worse prognosis than younger women in both early stage disease, and more advanced and metastatic disease. Focus on the treatment of older adults has often concentrated on avoiding overtreatment, but in fact undertreatment may be one reason for the age-related differences in outcomes, and treatments need to be individualized for every older adult, and take into account patient preferences and functional status and not chronologic age alone. Given the aging population in the US, identifying methods to improve early diagnosis in this population and identify additional factors will be important to reducing this age-related disparity.

Clinical outcomes with neoadjuvant versus adjuvant chemotherapy for triple negative breast cancer: A report from the National Cancer Database.

PURPOSE: Triple negative breast cancer (TNBC) patients frequently receive neoadjuvant chemotherapy (NAC). Only 50% will achieve pathological complete response (pCR). In this retrospective study, we evaluated TNBC outcomes with NAC vs. AC. METHODS: Patients with stages II and III TNBC treated with NAC or AC between 2010 and 2013 were identified from the National Cancer Database. Baseline characteristics were compared with χ2 and two sample t tests. Kaplan-Meier survival analyses were computed in patients treated with NAC or AC, and log-rank tests used to examine differences. Unadjusted analyses of trends in proportions over time were performed using Cochran-Armitage tests. Log-binomial models were applied to estimate relative risks of non-pCR following NAC. RESULTS: Of 19,151 patients, 5,621 (29.4%) received NAC, 13,530 (70.6%) received AC. NAC treated patients had worse OS compared to AC treated patients (73.4% vs. 76.8%; p<0.0001). pCR rate following NAC was 47.4%, and was associated with improved 5 year OS compared to non-pCR (86.2% vs. 62.3%; p<0.0001). In patients who received NAC, age, black race, clinical stage, diagnosis year, and Charlson-Deyo comorbidity score predicted non-pCR status. Use of NAC increased over the study period from 2010 to 2013 (27.8% - 31.2%; p = 0.0002). CONCLUSIONS: NAC may be inferior to AC in TNBC, likely related to the high frequency of non-pCR following NAC. It is unclear if removing the primary tumor prior to chemotherapy will have a beneficial biologic impact on therapeutic efficacy. These data should be considered hypothesis-generating as it is possible that the findings are due to selection bias, as physicians may use NAC for TNBC patients with more advanced local disease. Although, NAC still has a role in TNBC, developing biomarkers to identify patients likely to achieve pCR and benefit from NAC is an urgent need.

Solution structure of inhibitor-free human metalloelastase (MMP-12) indicates an internal conformational adjustment.

Macrophage metalloelastase or matrix metalloproteinase-12 (MMP-12) appears to exacerbate atherosclerosis, emphysema, aortic aneurysm, rheumatoid arthritis, and inflammatory bowel disease. An inactivating E219A mutation, validated by crystallography and NMR spectra, prevents autolysis of MMP-12 and allows us to determine its NMR structure without an inhibitor. The structural ensemble of the catalytic domain without an inhibitor is based on 2813 nuclear Overhauser effects (NOEs) and has an average RMSD to the mean structure of 0.25 A for the backbone and 0.61 A for all heavy atoms for residues Trp109-Gly263. Compared to crystal structures of MMP-12, helix B (hB) at the active site is unexpectedly more deeply recessed under the beta-sheet. This opens a pocket between hB and beta-strand IV in the active-site cleft. Both hB and an internal cavity are shifted toward beta-strand I, beta-strand III, and helix A on the back side of the protease. About 25 internal NOE contacts distinguish the inhibitor-free solution structure and indicate hB's greater depth and proximity to the sheet and helix A. Line broadening and multiplicity of amide proton NMR peaks from hB are consistent with hB undergoing a slow conformational exchange among subtly different environments. Inhibitor-binding-induced perturbations of the NMR spectra of MMP-1 and MMP-3 map to similar locations across MMP-12 and encompass the internal conformational adjustments. Evolutionary trace analysis suggests a functionally important network of residues that encompasses most of the locations adjusting in conformation, including 18 residues with NOE contacts unique to inhibitor-free MMP-12. The conformational change, sequence analysis, and inhibitor perturbations of NMR spectra agree on the network they identify between structural scaffold and the active site of MMPs.