HER2-positive Subgroup Research Articles

Prediction of the number of positive axillary lymph nodes according to sentinel lymph node involvement and biological subtypes in patients receiving neoadjuvant chemotherapy

BackgroundSentinel lymph node biopsy (SLNB) has replaced axillary lymph node dissection (ALND) for assessing axillary lymph node status in clinically node-negative breast cancer patients. However, the approach to axillary surgery after neoadjuvant treatment is still controversial. In the present study, our objective was to predict the pathological nodal stage based on SLNB results and the clinicopathological characteristics of patients who initially presented with clinical N1 positivity but whose disease status was converted to clinical N0 after neoadjuvant chemotherapy (NAC).Materials and methodsAfter NAC, 150 clinically node-negative patients were included. The relationships between clinicopathologic parameters and the number of positive lymph nodes in SLNBs and ALNDs were assessed through binary/multivariate logistic regression analysis.ResultsAmong 150 patients, 78 patients had negative SLNBs, and 72 patients had positive SLNBs. According to the ALND data of 21 patients with SLNB1+, there was no additional node involvement (80.8%), 1–2 lymph nodes were positive in 5 patients (19.2%), and no patient had ≥ 3 lymph nodes involved. Following the detection of SLNB1 + positivity, the rate of negative non-sentinel nodes were 75% in the luminal A/B subgroup, 100% in the HER-2-positive subgroup, and 100% in the triple-negative subgroup. Patients with a lower T stage (T1-3 vs. T4), fewer than 4 clinical nodes before NAC (< 4 vs. ≥4), and a decreased postoperative Ki-67 index (< 10% vs. stable/increase) were included. According to both univariate and multivariate analyses, being in the triple-negative or HER2-positive subgroup, compared to the luminal A/B subgroup (luminal A/B vs. HER2-positive/triple-negative), was found to be predictive of complete lymph node response.ConclusionThe number of SLNB-positive nodes, tumor-related parameters, and response to treatment may predict no additional nodes to be positive at ALND.

Clinicopathological characteristics and prognostic significance of casting-type calcifications in patients with invasive breast cancer presenting with microcalcification

To explore the clinicopathological characteristics and prognostic significance of casting-type calcification (CC) in patients with breast cancer presenting with microcalcification on mammography. Data on patients with invasive breast cancer who had mammographic calcification was retrospectively analyzed. The chi-square test was utilized to assess the clinicopathological characteristics of two forms of CC-related breast cancer. The examination of prognostic variables was conducted using Kaplan–Meier and Cox regression analyses. A total of 427 eligible patients were included in this study. Chi-square analysis indicated that the presence of CC was associated with estrogen receptor (ER) negativity (P = 0.005), progesterone receptor (PR) negativity (P < 0.001), and epidermal growth factor receptor 2 (HER-2) positivity (P < 0.001); among these, the association was stronger with the CC-predominant type. After a median follow-up of 82 months, those with CC had a worse 5-year recurrence-free survival (RFS) (77.1% vs. 86.9%, p = 0.036; hazard ratio [HR], 1.86; 95% confidence interval [CI] 1.04–3.31) and overall survival (OS) (84.0% vs. 94.4%, p = 0.007; HR, 2.99; 95% CI 1.34–6.65) rates. In COX regression analysis, such differences were still observed in HER-2 positive subgroups (RFS: HR: 2.45, 95% CI 1–5.97, P = 0.049; OS: HR: 4.53, 95% CI 1.17–17.52, P = 0.029). In patients with invasive breast cancer exhibiting calcifications on mammography, the presence of CC, especially the CC-predominant type, is linked to a higher frequency of hormone receptor negativity and HER-2 positivity. The presence of CC is associated with an unfavorable 5-year RFS and OS rates.

Free Salivary Amino Acid Profile in Breast Cancer: Clinicopathological and Molecular Biological Features.

The study of salivary amino acid profiles has attracted the attention of researchers, since amino acids are actively involved in most metabolic processes, including breast cancer. In this study, we analyzed the amino acid profile of saliva in a sample including all molecular biological subtypes of breast cancer to obtain a more complete picture and evaluate the potential utility of individual amino acids or their combinations for diagnostic purposes. This study included 116 patients with breast cancer, 24 patients with benign breast disease, and 25 healthy controls. From all patients, strictly before the start of treatment, saliva samples were collected, and the quantitative content of 26 amino acids was determined. Statistically significant differences between the three groups are shown in the content of Asp, Gly, Leu + Ile, Orn, Phe, Pro, Thr, and Tyr. To differentiate the three groups from each other, a decision tree was built. To construct it, we selected those amino acids for which the change in concentrations in the subgroups was multidirectional (GABA, Hyl, Arg, His, Pro, and Car). For the first time, it is shown that the amino acid profile of saliva depends on the molecular biological subtype of breast cancer. The most significant differences are shown for the luminal B HER2-positive and TNBC subgroups. In our opinion, it is critically important to consider the molecular biological subtype of breast cancer when searching for potential diagnostic markers.

Abstract PO5-18-09: Anthracycline-free neoadjuvant therapy with nab-paclitaxel and carboplatin in non-luminal breast cancer: a single-arm phase II trial

Abstract Background Anthracycline and taxane-based chemotherapy are the corner stone of neoadjuvant therapy in early breast cancer. Anthracycline-free regimens have been addressed widely because of cardiac toxicity especially in HER2-positive breast cancer when combining trastuzumab and pertuzumab. Aim of this trial was to assess the efficacy and safety of nab-paclitaxel combined with carboplatin in the neoadjuvant therapy of non-luminal breast cancer. Methods The Neopath trial was a prospective, single-arm phase II trial conducted in Comprehensive Breast Health Center, Ruijin Hospital between April 2019 and October 2021. Patients who had cT2-4NanyM0 or cTanyN1-3M0 triple negative breast cancer (TNBC) or HER2-positive breast cancer were enrolled. Patients were treated with neoadjuvant nab-paclitaxel (100 mg/m2) and carboplatin (area under the curve 2) on days 1, 8, and 15, for four 4-week cycles. Concurrent trastuzumab at 2 mg/kg (loading dose 4 mg/kg) and pertuzumab 420 mg (loading dose 840 mg) were given in patients with HER2-positive tumors. Surgery was performed after 4-6 cycles of neoadjuvant therapy. Trastuzumab and pertuzumab after surgery was continued every 3 weeks for a total duration of 1 year. The primary endpoint was pathological complete response (pCR) rate, defined as no invasive tumor in breast and axillary lymph nodes (ypT0/Tis N0) after neoadjuvant therapy. Secondary endpoints were pCR rate in predefined subgroups, pCR (ypT0 N0), objective response rate (ORR); event-free survival (EFS), breast conservation rate and toxicity. Results A total of 106 patients were enrolled in the study and 99 of them proceeded to surgery. The pCR (ypT0/is N0) rate was 41.41% in total, 33.78% in TNBC and 64.00% in HER2-positive breast cancer. Proportion of patients achieving pCR (ypT0 N0) was 38.38% in total, 31.08% in TNBC and 60.00% in HER2-positive tumors. In the ITT population, 93 patients were event-free at a median follow-up of 24 months, while 5 in TNBC group and 1 in HER2-positive group had relapse or distant metastasis. EFS in patients achieving pCR was higher than patients without pCR (HR=7.328, 95%CI=1.453-36.96, p=0.0158). ORR was 72.49% in total, 67.12% in TNBC and 88.00% in HER2-positive breast cancer. Total breast conservation rate was 10.1% and 12.2% in TNBC, 4.0% in HER2-positive subgroup. The most frequent grade 3 or higher adverse events were neutropenia (57%), vomiting (11%) and thrombocytopenia (8%). Conclusion Neoadjuvant anthracycline-free regimen of nab-paclitaxel combined with carboplatin in non-luminal breast cancer was an effective and well-tolerated regimen. Citation Format: Deyue Liu, Li Zhu, Jiayi Wu, Wei Wang, Shuning Ding. Anthracycline-free neoadjuvant therapy with nab-paclitaxel and carboplatin in non-luminal breast cancer: a single-arm phase II trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-18-09.

Abstract PO3-04-05: Efficacy and safety of the recombinant humanized anti-HER2 monoclonal antibody-MMAE conjugate RC48-ADC in patients with HER2-positive or HER2-low expressing, metastatic breast cancer: a single-arm phase II study

Abstract Background: Current treatment options for HER2-positive (IHC 3+, or IHC 2+/FISH+) advanced or metastatic breast cancer at third-line and above have shown limited clinical benefit. There is no recommended HER2-targeting treatment for HER2-low expressing (IHC 2+/FISH-, or IHC 1+) population. RC48 (Disitamab vedotin), a newly developed antibody-drug conjugate (ADC), is comprised of three well-defined components: hertuzumab against the prominent tumor target-HER2, monomethyl auristatin E (MMAE) and a cleavable linker, with a bystanding effect in tumor cell killing. There is a lack of data on the administration of RC48 in the Chinese population. Here, we report the efficacy and safety of RC48-ADC in the advanced or metastatic breast cancer. Methods: Patients with HER2-positive or HER2-low expressing, locally advanced or metastatic breast cancer were eligible and received RC48 2.5 mg/kg every two weeks alone or combined with drugs with different anti-tumor mechanisms, such as immune checkpoint inhibitors (ICIs), tyrosine kinase inhibitors (TKIs) and antiangiogenic compounds. The primary endpoint was the objective response rate (ORR) assessed by the primary researcher. Secondary endpoints included progression-free survival (PFS), overall survival (OS), disease control rate (DCR), time to progression, and safety. Results: At the time of data cutoff (June 30, 2023), 120 chinese female breast cancer patients were enrolled and treated with RC48-ADC. 82 patients (68.3%) were HER2-positive and 38 patients (31.7%) were HER2-low expressing. At baseline, 52 patients (43.3%) had liver metastases, 40 patients (33.3%) had brain metastases, 70 patients (58.3%) had ≥3 metastases lesions, and 84 patients (70.0%) had received ≥3 prior chemotherapy regimens. In the overall population, the ORR was 38.3% (95% confidence interval [CI]: 30.0%-47.3%). The median PFS was 5.7 months (95% CI: 4.6-6.9 months). The DCR was 64.2% (95% CI: 54.9%-72.6%). In the HER2-positive subgroup, the ORR and mPFS were 42.7% (95% CI: 32.0%-54.1%) and 6.3 months (95% CI: 4.9-7.6 months). In the HER2-low expressing subgroup, the ORR and mPFS were 29.0% (95% CI: 16.0%-46.1%) and 3.6 months (95% CI: 2.0-5.3 months). In addition, the mPFS in the dual drug combination-treated group were longer than those in the single drug treatment group, with mPFS of 7.1 months (95% CI: 5.0-9.2 months) and 4.6 months (95% CI: 3.5-5.8 months), respectively. The most frequently reported treatment-related adverse events (TRAEs) were increased AST (45.8%), increased ALT (41.7%), decreased white blood cell count (25.0%), and fatigue (25%), most were grade 1-2 in severity. Conclusions: RC48-ADC showed consistent efficacy in HER2-positive and HER2-low expressing subgroups. No new safety signals were observed. Coadministration with ICIs, TKIs and antiangiogenic compounds demonstrated substantially enhanced efficacy compared to the monotherapies and could be a future direction in development of ADC. Citation Format: Fei Qu, Wei Li, Yongmei Yin, Qian Liu. Efficacy and safety of the recombinant humanized anti-HER2 monoclonal antibody-MMAE conjugate RC48-ADC in patients with HER2-positive or HER2-low expressing, metastatic breast cancer: a single-arm phase II study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-04-05.

Abstract PO1-27-11: Survival Benefit of Adjuvant Endocrine Therapy in Patients with Estrogen Receptor Low-Positive Breast Cancer

Abstract Background: Estrogen receptor (ER) low-positive (1–10%) breast cancer is a very rare subtype that accounts for only 2–5% of all breast cancer cases and was introduced as a new category in the 2020 American Society of Clinical Oncology/College of American Pathologist Guidelines. There are limited data on the overall benefit of endocrine therapy for patients with ER low-positive cancers. The objective of this study was to analyze the clinicopathological characteristics and treatment patterns in patients with ER low-positive breast cancer and to compare disease-free survival (DFS) between patients who received and did not receive endocrine therapy. Methods: A retrospective search of the prospectively maintained database of our institution identified consecutive women with ER low-positive (1–10%) primary invasive breast cancer who underwent curative surgery at Seoul National University Hospital (Seoul, Korea) between January 2010 and April 2021. Standard immunohistochemical staining techniques were used to assess the level of ER, progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression, and semiquantitative scores (0–100%) were reported for ER and PR. DFS was defined as the time from surgery to the development of any recurrence and was compared between women who received and did not receive adjuvant endocrine therapy using univariable and multivariable Cox proportional hazards regression. Results: A total of 721 women (median age, 51 years; range, 24–83 years) with ER low-positive cancer were included in the analysis. Overall, 28% (203/721) had AJCC stage I, 42% (304/721) had stage II, and 30% (214/721) had stage III. PR expression was negative (&amp;lt; 1%) in 79% (571/721), low-positive (1–10%) in 12% (90/721), and high-positive ( &amp;gt;10%) in 8% (60/721). HER2 expression was negative in 54% (390/721) and positive in 46% (331/721). Most women (88% [634/721]) received adjuvant endocrine therapy, including all women with PR expression &amp;gt;10%. Of the 661 women with PR expression ≤10%, 87 (13%) did not receive adjuvant endocrine therapy. HER2-targeted therapy was performed in 81% (268/331) of women with HER2-positive cancer. During a median follow-up of 5.7 years, 98 (14%) had recurrence (25 locoregional/contralateral and 73 distant metastases). AJCC stage III (HR, 3.6; 95% CI: 2.4, 5.4; P &amp;lt; .001) and receiving total mastectomy (HR, 1.8; 95% CI: 1.2, 2.8; P = .004) were associated with worse DFS. Receiving adjuvant endocrine therapy was independently associated with better DFS in the entire cohort (HR, 0.46; 95% CI: 0.28, 0.76; P = .002) and in the HER2-negative subgroup (HR, 0.40; 95% CI: 0.22, 0.75; P = .004). In the HER2-positive subgroup, receiving adjuvant endocrine therapy was not significantly associated with better DFS (HR, 0.55; 95% CI: 0.23, 1.32; P = .18). Conclusion: In this large cohort of women with ER low-positive breast cancers, adjuvant endocrine therapy was administered in the majority of cases, including those with PR &amp;gt;10% expression. Receiving adjuvant endocrine therapy was associated with better DFS, especially when HER2 expression was negative. Citation Format: Su Hyun Lee, Han Suk Ryu, Myoung-jin Jang, Kyung-Hun Lee, Han-Byoel Lee. Survival Benefit of Adjuvant Endocrine Therapy in Patients with Estrogen Receptor Low-Positive Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-27-11.

Kataegis in clinical and molecular subgroups of primary breast cancer

Kataegis is a hypermutation phenomenon characterized by localized clusters of single base pair substitution (SBS) reported in multiple cancer types. Despite a high frequency in breast cancer, large-scale analyses of kataegis patterns and associations with clinicopathological and molecular variables in established breast cancer subgroups are lacking. Therefore, WGS profiled primary breast cancers (n = 791) with associated clinical and molecular data layers, like RNA-sequencing data, were analyzed for kataegis frequency, recurrence, and associations with genomic contexts and functional elements, transcriptional patterns, driver alterations, homologous recombination deficiency (HRD), and prognosis in tumor subgroups defined by ER, PR, and HER2/ERBB2 status. Kataegis frequency was highest in the HER2-positive(p) subgroups, including both ER-negative(n)/positive(p) tumors (ERnHER2p/ERpHER2p). In TNBC, kataegis was neither associated with PAM50 nor TNBC mRNA subtypes nor with distant relapse in chemotherapy-treated patients. In ERpHER2n tumors, kataegis was associated with aggressive characteristics, including PR-negativity, molecular Luminal B subtype, higher mutational burden, higher grade, and expression of proliferation-associated genes. Recurrent kataegis loci frequently targeted regions commonly amplified in ER-positive tumors, while few recurrent loci were observed in TNBC. SBSs in kataegis loci appeared enriched in regions of open chromatin. Kataegis status was not associated with HRD in any subgroup or with distinct transcriptional patterns in unsupervised or supervised analysis. In summary, kataegis is a common hypermutation phenomenon in established breast cancer subgroups, particularly in HER2p subgroups, coinciding with an aggressive tumor phenotype in ERpHER2n disease. In TNBC, the molecular implications and associations of kataegis are less clear, including its prognostic value.

HER2 categorical changes after neoadjuvant chemotherapy: A study of 192 matched breast cancers with the inclusion of HER2-Low category

Understanding the changes of HER2 expression after neoadjuvant chemotherapy (NAC) in breast cancer (BC) is more important than ever, since it may allow more patients to access the effective therapeutic drugs targeting HER2-low BC. 192 matched pre- and post-NAC BCs were analyzed. HER2 immunohistochemistry (IHC) was re-evaluated with consensus according to the current ASCO/CAP guidelines. Tumors were categorized into HER2-0 (IHC0+), HER2-low (IHC1+ or IHC2+/ISH-) and HER2-positive (IHC3+ or IHC2+/ISH+) subgroups. 55 (28.6 %) patients achieved pathologic complete response (pCR). HER2-low BC accounted for 75/192 (39.1 %) baseline tumors, and 48/133 (36.1 %) residual tumors. In the non-pCR cohort, 53 (39.9 %) patients had HER2 categorical change after NAC, most commonly converting from HER2-low to HER2-0 (20.3 %, n = 27). Among patients with residual tumor, 25.6 % (11/43) of patients with baseline HER2-0 expression experienced a categorical change to HER2-low after NAC, significantly higher (p < 0.05) in the hormone receptor (HR) positive (9/23, 39.1 %) compared to the HR negative tumors (10 %, 2/20). Exploratory analysis failed to reveal a statistically significant difference in disease free survival and overall survival in non-pCR patients with or without HER2 change. Our results suggest that a substantial number of patients may experience HER2 categorical change after NAC, supporting re-testing of HER2 status in post-NAC residual tumors. Retesting HER2 status may be particularly important for evaluating post-NAC HER2-low status, in order to better assess which patients will more likely benefit from therapeutic drugs targeting HER2-low BC.

Neoadjuvant Systemic Therapy in Early Breast Cancer: Results of a Prospective Observational Multicenter BRIDE Study.

To evaluate the rate of early breast cancer (EBC) patients treated with neoadjuvant systemic therapy (NAT) in Italy, criteria of patient selection and types of therapies delivered, an analysis of 1276 patients with stage I-II-III was conducted out of 1633 patients enrolled in the multicenter prospective observational BRIDE study. A total of 177 patients (13.9%) were treated with NAT and 1099 (85.9%) with surgery; in multivariate analysis, menopausal status, cT, cN, grade, HER2-positive and Triple negative (TN) subgroups were significantly associated with the decision to administer NAT. The type of NAT delivered was influenced by EBC subtype. NAT was administered to 53.2% of HER2+/HR-negative, 27.9% of HER2+/HR+, 7.1% of HER2-negative/HR+ and 30.3% of TN EBC patients. The pCR rates were similar to the ones reported in the literature: 74.2% in HER2+/HR-negative, 52.3% in HER2+/HR+, 17.2% in HER2-negative/HR+ and 37.9% in TN. In clinical practice, patient and tumor characteristics influenced oncologists in the decision to administer NAT in EBC and in the choice of the type of systemic therapy, according to ESMO and AIOM Guidelines. Currently, it is recommended always to evaluate the use of NAT in EBC, mainly in HER2+ and TN patients, considering that pCR is associated with significantly better survival of the patient and that effective therapies are now available for residual disease.

Abstract P2-26-06: Association between CK+/CD45+ circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) alterations in advanced breast cancer patients

Abstract Background: Circulating tumor cells (CTCs) in breast cancer (BC) are commonly defined as epithelial cells (EPCAM and cytokeratin (CK) positive), lacking the universal blood cell marker CD45. Nonetheless, CTCs expressing both CK and CD45 (= dual-positive, DP cells) can be observed in the blood of cancer patients. Early evidence suggests that DP cells might derive from the fusion of tumor cells and macrophages, and we have previously demonstrated that they present aberrant genomes and are associated with worse prognosis in BC [1,2]. Here, to further investigate the mechanisms/pathways underlying their presence, we analyzed the association between DP cells and circulating tumor DNA (ctDNA) alterations. Methods: Blood samples were collected from patients with advanced BC (aBC), before starting a new line of therapy. All patients were enrolled in a prospective clinical trial. For CTC and DP cells analysis, 7.5 ml of blood collected in CellSave® tubes was processed with the FDA-approved CellSearch® platform (positivity cutoffs were ≥1 cell for DPcells and ≥5 cells for CTCs). For ctDNA analysis, plasma was collected from Streck stabilizing tubes and analyzed with the Guardant360™ NGS platform for the detection of somatic single nucleotide variants (SNVs), insertions/deletions (indels), gene fusions/rearrangements and copy number variations (CNVs), which were then classified into pathways based on previously defined profiles generated on the Cancer Genome Atlas database (RTK, RAS, RAF, MEK, NRF2, ER, WNT, MYC, P53, cell cycle, notch, PI3K). Associations between ctDNA-detected gene alterations and circulating cell types were analyzed through chi square test, while mutant allele frequency (MAF) and number of detected alterations (NDA) were tested by Mann Whitney test. Results: We analyzed blood samples from 169 patients with luminal-like (n=80), HER2+ (n=34) and triple-negative (n=52) aBC. DPcells were detected in 85 patients (50.3 %, range 0-53), of which 40 (47 %) were CTC-positive and 45 (53%) CTC-negative. Somatic ctDNA alterations were detected in all analyzed samples. In the overall population, the presence of ≥1 DPcell was associated with SNVs in the cell cycle pathway (p = 0.043), a numerically higher incidence was also observed for CNVs in this pathway. SNVs and CNVs in the cell cycle pathway were associated with CTCs ≥ 5 as well (p = 0.005 and p = 0.003, respectively). Moreover, associations with CTCs ≥ 5 were observed for RTK SNVs and CNVs (p = 0.041 and p = 0.046, respectively), PI3K SNVs and CNVs (p = 0.006 and p = 0.007, respectively), MYC SNVs and CNVs (p = 0.042). No associations were observed in terms of MAF and NDA. In the luminal-like subgroup an association was highlighted for CNVs in the cell cycle pathway, p = 0.038. CTCs ≥ 5 were associated with PI3K SNVs (p = 0.031). In the triple-negative subgroup DPcells were associated with SNVs in the RAF pathway (p = 0.041), whereas CTCs ≥ 5 were associated with PI3K SNVs and CNVs (p = 0.044 and p = 0.024, respectively) and RTK SNVs (p = 0.008). In the HER2 positive subgroup, a higher MAF and number of detected SNVs was observed for samples with ≥1 DPcell (p = 0.0286 and p = 0.0099, respectively). Conclusions: The study analyzed ctDNA features associated with canonical and CK+/CD45+ CTCs, showing differential gene alteration profiles. Cell cycle pathway SNVs were common in both CTC populations, while other pathways (RTK, PI3K, MYC and RAF) were significantly altered in a mutually exclusive pattern. These results suggest that DPcells might have a different biological meaning compared to canonical CTCs. More studies need to be conducted to better characterize this understudied CTC subpopulation and understand their specific contribution to cancer progression.

Translational Results of Zo-NAnTax: A Phase II Trial of Neoadjuvant Zoledronic Acid in HER2-Positive Breast Cancer.

Breast cancer is a heterogeneous disease with distinct clinical and molecular characteristics. Scientific advances in molecular subtype differentiation support the understanding of cellular signaling, crosstalk, proliferation, survival, migration, and invasion mechanisms, allowing the development of new molecular drug targets. The breast cancer subtype with super expression and/or amplification of human growth factor receptor 2 (HER2) is clinically aggressive, but prognosis significantly shifted with the advent of anti-HER2 targeted therapy. Zoledronic-acid (ZOL) combined with a neoadjuvant Trastuzumab-containing chemotherapy regimen (Doxorubicin, Cyclophosphamide followed by Docetaxel, Trastuzumab) increased the pCR rate in a RH-positive/ HER2-positive subgroup, according to the phase II Zo-NAnTax trial. To verify genes that could be related to this response, a microarray assay was performed finding 164 differentially expressed genes. Silico analysis of these genes showed signaling pathways related to growth factors, apoptosis, invasion, and metabolism, as well as differentially expressed genes related to estrogen response. In addition, the RAC3 gene was found to interact with the MVD gene, a member of the mevalonate pathway. Taken together, these results indicate that RH-positive/ HER2-positive patients present gene alterations before treatment, and these could be related to the improvement of pCR.

Assessment of Prognostic Factors and Molecular Subtypes of Breast Cancer With a Continuous-Time Random-Walk MR Diffusion Model: Using Whole Tumor Histogram Analysis.

The continuous-time random-walk (CTRW) diffusion model to evaluate breast cancer prognosis is rarely reported. To investigate the correlations between apparent diffusion coefficient (ADC) and CTRW-specific parameters with prognostic factors and molecular subtypes of breast cancer. Retrospective. One hundred fifty-seven women (median age, 50 years; range, 26-81 years) with histopathology-confirmed breast cancer. Simultaneous multi-slice readout-segmented echo-planar imaging at 3.0T. The histogram metrics of ADC, anomalous diffusion coefficient (D), temporal diffusion heterogeneity (α), and spatial diffusion heterogeneity (β) were calculated for whole-tumor volume. Associations between histogram metrics and prognostic factors (estrogen receptor [ER], progesterone receptor [PR], human epidermal growth factor receptor 2 [HER2], and Ki-67 proliferation index), axillary lymph node metastasis (ALNM), and tumor grade were assessed. The performance of histogram metrics, both alone and in combination, for differentiating molecular subtypes (HER2-positive, Luminal or triple negative) was also assessed. Comparisons were made using Mann-Whitney test between different prognostic factor statuses and molecular subtypes. Receiver operating characteristic curve analysis was used to assess the performance of mean and median histogram metrics in differentiating the molecular subtypes. A P value <0.05 was considered statistically significant. The histogram metrics of ADC, D, and α differed significantly between ER-positive and ER-negative status, and between PR-positive and PR-negative status. The histogram metrics of ADC, D, α, and β were also significantly different between the HER2-positive and HER2-negative subgroups,and between ALNM-positive and ALNM-negative subgroups. The histogram metrics of α and β significantly differed between high and low Ki-67 proliferation subgroups, and between histological grade subgroups. The combination of αmean and βmean achieved the highest performance (AUC=0.702) to discriminate the Luminal and HER2-positive subtypes. Whole-tumor histogram analysis of the CTRW model has potential to provide additional information on the prognosis and intrinsic subtyping classification of breast cancer. 4 TECHNICAL EFFICACY: Stage 2.

Putative Clinical Potential of ERBB2 Amplification Assessment by ddPCR in FFPE-DNA and cfDNA of Gastroesophageal Adenocarcinoma Patients.

Simple SummaryGastroesophageal adenocarcinoma (GEA) has a poor prognosis. However, since the HER2 positive subgroup could benefit from trastuzumab targeted therapy, considerable effort has been spent in determining the HER2 status in these patients. To date, immunohistochemistry and in situ hybridization are the gold standard methods for assessing HER2/ERBB2 overexpression/amplification in tumor specimens. However, they have several limitations due to their cost, the large number of undetermined cases, and the impossibility of longitudinal patient monitoring. Here, we report the potential of a molecular method (droplet digital PCR) to investigate ERBB2 status in both solid and liquid biopsies of GEA. Results suggest that this methodology could be used to implement current histological analysis in solid biopsy and that it may be feasible in liquid biopsy. An alternative, more sensitive method of assessing HER2 status may aid physicians in their therapeutic decision-making, benefiting the patient. Liquid biopsy could also overcome the limitations of tissue-based analyses.Anti-HER2 monoclonal antibody trastuzumab improves the survival of those patients with advanced gastroesophageal adenocarcinoma (GEA) exhibiting HER2/ERBB2 overexpression/amplification. The current gold standard methods used to diagnose the HER2 status in GEA are immunohistochemistry (IHC) and silver or fluorescence in situ hybridization (SISH or FISH). However, they do not permit spatial and temporal tumor monitoring, nor do they overcome intra-cancer heterogeneity. Droplet digital PCR (ddPCR) was used to implement the assessment of HER2 status in formalin-fixed paraffin-embedded (FFPE) tumor DNA from a retrospective cohort (86 patients) and in cell-free DNA (cfDNA) samples from a prospective cohort (28 patients). In comparison to IHC/SISH, ddPCR assay revealed ERBB2 amplification in a larger patient fraction, including HER2 2+ and 0–1+ of the retrospective cohort (45.3% vs. 15.1%). In addition, a considerable number of HER2 2+ and 0–1+ prospective patients who were negative in FFPE by both IHC/SISH and ddPCR, showed ERBB2 amplification in the cfDNA collected just before surgery. cfDNA analysis in a few longitudinal cases revealed an increasing ERBB2 trend at progression. In conclusion, ddPCR in liquid biopsy may improve the detection rate of HER2 positive patients, preventing those patients who could benefit from targeted therapy from being incorrectly excluded.

CIP2A as a Key Regulator for AKT Phosphorylation Has Partial Impact Determining Clinical Outcome in Breast Cancer.

Together with its reported ability to modulate AKT phosphorylation (p-AKT) status in several tumor types, the oncoprotein CIP2A has been described to induce breast cancer progression and drug resistance. However, the clinical and therapeutic relevance of the CIP2A/AKT interplay in breast cancer remains to be fully clarified. Here, we found high p-AKT levels in 80 out of 220 cases (36.4%), which were associated with negative estrogen receptor expression (p = 0.049) and CIP2A overexpression (p < 0.001). Interestingly, p-AKT determined substantially shorter overall (p = 0.002) and progression-free survival (p = 0.003), and multivariate analyses showed its CIP2A-independent prognostic value. Moreover, its clinical relevance was further confirmed in the triple negative and HER2-positive subgroups after stratifying our series by molecular subtype. Functionally, we confirmed in vitro the role of CIP2A as a regulator of p-AKT levels in breast cancer cell lines, and the importance of the CIP2A/AKT axis was also validated in vivo. Finally, p-AKT also showed a higher predictive value of response to doxorubicin than CIP2A in ex vivo analyses. In conclusion, our findings suggest that CIP2A overexpression is a key contributing event to AKT phosphorylation and highlights the CIP2A/AKT axis as a promising therapeutic target in breast cancer. However, our observations highlight the existence of alternative mechanisms that regulate AKT signaling in a subgroup of breast tumors without altered CIP2A expression that determines its independent value as a marker of poor outcome in this disease.

Abstract P2-01-01: Genetic alterations detected by circulating tumor DNA (ctDNA) in HER2-low metastatic breast cancer (MBC)

Abstract Introduction: Approximately 40-50% of breast cancers are characterized by low HER2 expression (HER2-low), defined as immunohistochemistry (IHC) 1+ or 2+ and HER2 fluorescence in situ hybridization (FISH) unamplified, encompassing a large and heterogeneous subgroup that may confer benefit from novel HER2 directed therapies. Circulating tumor DNA (ctDNA) has emerged as a minimally invasive technique to detect cancer-specific gene aberrations. Genetic alterations in ctDNA of HER2-low MBC have not been well described, and we hypothesized that HER2-low MBC may have a distinct genomic profile, beyond standard histopathologic features. Methods: This retrospective cohort study included patients with MBC treated at Washington University in St. Louis, Northwestern University (Chicago, IL) and Massachusetts General Hospital (Boston, MA) who had undergone ctDNA analysis during the course of treatment using the commercially available Guardant360® assay. HER2 expression was evaluated by IHC/FISH according to ASCO/CAP guidelines on metastatic tissue biopsies (or primary breast tumor tissue if a metastatic site biopsy was not available). Tumors were classified as HER2-low (IHC 1+ or 2+/FISH negative), HER2-0 (IHC 0) or HER2-positive (IHC 3+ or IHC 2+/FISH amplified). Clinicopathologic characteristics and ctDNA genetic alterations for HER2-low MBC were described and compared with the HER2-0 and HER2-positive subgroups. Chi-square and Fisher’s exact tests were used for categorical variables. Logistical regression was performed for multivariable analyses. Results: A total of 991 patients with MBC were analyzed, including 160 (16.1%) HER2-positive, 351 (35.4%) HER2-0, and 480 (48.4%) HER2-low MBC. The majority (89.2%) of HER2-low MBC were estrogen-receptor positive (ER+). Compared with HER2-0 MBC, HER2-low MBC had a significantly higher incidence of PIK3CA mutations (OR 1.54, p=0.027). PDGFRA and MYC amplifications were also more common among HER2-low MBC (2.3% vs 0.28% and 8.1% vs 4.6%, respectively), although not significantly associated with this subtype in multivariable analysis. Within the ER+ MBC cohort, those with HER2-low also had higher rates of PIK3CA mutations (OR 1.66, p=0.012) and MYC amplification (OR 2.29, p=0.034), as compared to HER2-0. Compared with HER2-positive, HER2-low MBC had significantly lower rates of ERBB2 alterations (OR 0.26, p=0.0076 for ERBB2 mutations and OR 0.022, p&amp;lt;0.001 for ERBB2 amplification). ESR1, AKT1, and RB1 mutations were more common in HER2-low compared with HER2-positive MBC (14.0% vs 6.9%; 3.1% vs none; 3.1% vs none, respectively), but were not significant in multivariable analysis. Conclusions: Among patients with ER+ MBC, HER-low had a higher incidence of PIK3CA mutations and MYC amplification compared to HER2-0 MBC, and both of these alterations have been implicated as mechanisms of endocrine resistance. We did not demonstrate a high incidence of ERBB2 alterations in patients with HER2-low MBC. To our knowledge, this is the first study to describe genetic alterations detected by ctDNA in patients with HER2-low MBC. Given the emergence of novel HER2-targeted antibody drug conjugates with clinical activity in HER2-low MBC, these findings may guide combination treatment strategies and patient selection for future studies. Further studies are needed to confirm whether HER2-low MBC represents a truly unique biologic subtype. Citation Format: Whitney L Hensing, Lorenzo Gerratana, Katherine Clifton, Marko Velimirovic, Ami Shah, Paolo D'Amico, Carolina Reduzzi, Qiang Zhang, Charles S Dai, Nusayba A Bagegni, Mateusz Opyrchal, Foluso O Ademuyiwa, Bose Ron, Amir Behdad, Cynthia X Ma, Aditya Bardia, Massimo Cristofanilli, Andrew A Davis. Genetic alterations detected by circulating tumor DNA (ctDNA) in HER2-low metastatic breast cancer (MBC) [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 P2-01-01.

Changes in Ki-67 in Residual Tumor and Outcome of Primary Inflammatory Breast Cancer Treated With Trimodality Therapy

BackgroundLimited data are available on the prognostic role of Ki-67 changes in residual tumors after neoadjuvant chemotherapy in primary inflammatory breast cancer (IBC) patients treated with trimodality therapy. This study aims to evaluate changes in Ki-67 associated with disease-free survival (DFS) and overall survival (OS) in IBC patients without pathological complete response. Patients and MethodsWe identified a cohort of primary IBC patients with matched pre- and posttreatment samples treated with anthracycline and taxane-based regimen. All patients had a pathological evaluation, including ER, PR, HER2 status, and Ki-67 expression performed both at diagnostic core biopsy and at final surgery. Kaplan–Meier and Cox proportional hazards methods were used to assess DFS and OS rates and their relationship with clinicopathological features. ResultsTwo hundred and ten patients with stage III IBC were included. Sixty-three percent of residual tumors showed a decrease in Ki-67 positivity by at least 1%. The decrease of Ki-67 significantly correlated with better DFS (p = .001) and OS (P = .010) compared with no decrease, particularly in the luminal B-like and HER2-positive subgroups. The multivariate analysis showed that the decrease in Ki-67 level had a significant positive predictive value on DFS (HR = 0.47, 95% CI: 0.33-0.67; P< .001) and OS (HR = 0.59, 95% CI: 0.36-0.82; P= .004) in all IBC patients. ConclusionThe decrease of Ki-67 expression after neoadjuvant chemotherapy has a prognostic significance in IBC patients with residual disease. Evaluation of Ki-67 changes may help to identify subgroups of patients with worse outcome to receive novel treatment in this setting.

The impact of hormone receptor on the clinical outcomes of HER2-positive breast cancer: a population-based study

BackgroundTo investigate the impact of hormone receptor (HR) on the clinicopathological characteristics and prognosis of human epidermal growth factor receptor 2 (HER2)-positive breast cancer.MethodsUsing the Surveillance, Epidemiology, and End Results database, we enrolled patients diagnosed with HER2-positive breast cancer between 2010 and 2016, which were successively assessed for eligibility and categorized into HR + /HER2 + and HR-/HER2 + subgroups. Clinicopathological characteristics were undergone comparative analyses with the baseline distinctions calibrated by propensity score matching, while the survival outcomes were compared using Kaplan–Meier method with log-rank tests.ResultsA total of 46,803 HER2-positive breast cancer patients were identified, of which 32,919 individuals were HR + /HER2 + subtype and 13,884 individuals were HR-/HER2 + subtype, respectively. Comparatively, HR + /HER2 + breast cancer presented a lower histological grade, a smaller tumor size, a lower nodal involvement, and a lower rate of de novo stage IV disease. Substantial heterogeneity was detected in the metastatic patterns of organ-specific involvement between the two subgroups with initial metastasis. Overall, patients with HR + /HER2 + tumors had increasingly favorable prognosis in terms of overall survival and breast cancer-specific survival than patients with the HR−/HER2 + subtype. However, this kind of tendency exhibited disparities associated with HR-specific subtypes based on estrogen receptor (ER) and progesterone receptor (PgR) status, in which ER−/PgR + tended to present the worst prognosis.ConclusionThis study revealed profound heterogeneity associated with HR status in the clinical outcomes of HER2-positive breast cancer regarding clinicopathological features, metastatic patterns, and prognosis. Prospective studies to optimize therapeutic strategies for HER2-positive subgroups are warranted.

Antibiotics modulate neoadjuvant therapy efficiency in patients with breast cancer: a pilot analysis

Mounting evidence suggests that microbiota dysbiosis caused by antibiotic administration is a risk factor for cancer, but few research reports focus on the relationships between antibiotics and chemotherapy efficiency. We evaluated the influence of antibiotic administration on neoadjuvant therapy efficacy in patients with breast cancer (BC) in the present study. BC patients were stratified into two groups: antibiotic-treated and control based on antibiotic administration within 30 days after neoadjuvant therapy initiation. Disease-free survival (DFS) and overall survival (OS) were assessed using the Kaplan–Meier method, and the Cox proportional hazards model was used for multivariate analyses. The pathologic complete response rate of the control group was significantly higher than that of the antibiotic-treated group (29.09% vs. 10.20%, p = 0.017). Further univariate analysis with Kaplan–Meier calculations demonstrated that antibiotic administration was strongly linked with both reduced DFS (p = 0.04) at significant statistical levels and OS (p = 0.088) at borderline statistical levels. Antibiotic administration was identified as a significant independent prognostic factor for DFS [hazard ratio (HR) 3.026, 95%, confidence interval (CI) 1.314–6.969, p = 0.009] and OS (HR 2.836, 95% CI 1.016–7.858, p = 0.047) by Cox proportional hazards model analysis. Antibiotics that initiated reduced efficiency of chemotherapy were more noticeable in the HER2-positive subgroup for both DFS (HR 5.51, 95% CI 1.77–17.2, p = 0.003) and OS (HR 7.0395% CI 1.94–25.53, p = 0.003), as well as in the T3-4 subgroup for both DFS (HR 20.36, 95% CI 2.41–172.07, p = 0.006) and OS (HR 13.45, 95% CI 1.39–130.08, p = 0.025) by stratified analysis. Antibiotic administration might be associated with reduced efficacy of neoadjuvant therapy and poor prognosis in BC patients. As a preliminary study, our research made preparations for further understanding and large-scale analyses of the impact of antibiotics on the efficacy of neoadjuvant therapy.

RC48-ADC, a HER2-targeting antibody-drug conjugate, in patients with HER2-positive and HER2-low expressing advanced or metastatic breast cancer: A pooled analysis of two studies.

1022 Background: Currently, there are no standard ≥3 line regimens recommended for HER2-positive (IHC 3+, or IHC 2+/FISH+) advanced or metastatic breast cancer, and no recommended HER2-targeting treatment for HER2-low expressing (IHC 2+/FISH-, or IHC 1+) population. RC48-ADC is an innovative HER2-targeting antibody-drug conjugate with a cleavable linker and a potent microtubule inhibitor payload MMAE that has a bystanding effect in tumor cell killing. Methods: C001 CANCER (NCT02881138) was a dose-escalation phase I study (0.5, 1.0, 1.5, 2.0, and 2.5 mg/kg) with the 3+3 design among HER2-positive patients. C003 CANCER (NCT03052634) was a phase Ib study with 1.5, 2.0, and 2.5 mg/kg doses in the HER2-positive subgroup and 2.0 mg/kg dose in both IHC 2+/FISH-, and IHC 1+ HER2-low expressing subgroup. C003 CANCER is currently ongoing for IHC 1+ patients. Pooled analysis of the two studies was conducted for the efficacy and safety of RC48-ADC in HER2-positive or HER2-low expressing subgroups. Results: At the time of data cutoff (December 31, 2020), 118 female breast cancer patients were enrolled and treated with RC48-ADC. 70 patients (59.3%) were HER2-positive and 48 patients (40.7%) were HER2-low expressing. At baseline, 77 patients (65.3%) had liver metastases, 50 patients (42.4%) were ECOG PS 1, 47 patients (39.8%) had received ≥3 prior chemotherapy regimens. In the HER2-positive subgroup, ORRs for 1.5, 2.0, and 2.5 mg/kg doses were 22.2% (95% CI: 6.4%, 47.6%), 42.9% (95% CI: 21.8%, 66.0%), and 40.0% (95% CI: 21.1%, 61.3%). mPFSs for 1.5, 2.0, and 2.5 mg/kg cohorts were 4.0 months (95% CI: 2.6, 7.6), 5.7 months (95% CI: 5.3, 8.4) and 6.3 months (95% CI: 4.3, 8.8). In the HER2-low expressing subgroup, the ORR and mPFS were 39.6% (95% CI: 25.8%, 54.7%) and 5.7 months (95% CI: 4.1, 8.3). ORR and mPFS for IHC2+/FISH- patients were 42.9% (15/35) and 6.6 months (95% CI: 4.1, 8.5). For IHC1+ patients, even though the COVID-19 pandemic led to treatment postpone for some patients, ORR and mPFS reached 30.8% (4/13) and 5.5 months (95% CI: 2.7, 11.0). The common treatment-related adverse events (TRAEs) were AST increased (64.4%), ALT increased (59.3%), hypoesthesia (58.5%), white blood cell count decreased (48.3%), and neutrophil count decreased (47.5%); most were grade 1-2 in severity. Neutrophil count decreased (16.9%), GGT increased (12.7%), and fatigue (11.9%) were the grade 3 and above TRAEs occurring in ≥ 10% of the overall population. Conclusions: RC48-ADC showed consistent efficacy in HER2-positive and HER2-low expressing subgroups. The 2.0 mg/kg Q2W showed a more favorable benefit-risk ratio than other dose levels. No new safety signals were observed. Further studies are initiated to evaluate the efficacy and safety of RC48-ADC in various settings. Clinical trial information: NCT02881138; NCT03052634 .

Clinicopathologic characteristics of HER2-positive metaplastic squamous cell carcinoma of the breast

AimsThe aim of this study was to analyse the clinicopathological features and prognosis of human epidermal growth factor receptor-2 (HER2)-positive metaplastic squamous cell carcinoma (MSCC).MethodsFifty-eight patients with MSCC of the...