Preoperative factors that predict pathologic nodal involvement in early-stage HER2+ breast cancer: selecting cT1cN0 patients for treatment with neoadjuvant chemotherapy versus upfront surgery

PURPOSE

The goal of this study was to identify the preoperative predictors of pathologic nodal metastases (pN+) in cT1cN0 HER2+ breast cancer undergoing upfront surgery.

METHODS

We retrospectively reviewed data from women with cT1-T2N0 HER2+ breast cancer treated with neoadjuvant therapy (NAC) or upfront surgery at our institution between 2012 and 2023. Factors associated with management strategy were evaluated, and in those undergoing upfront surgery, univariate analyses were performed to identify the clinicopathologic factors associated with nodal metastases.

RESULTS

Overall, 255 women with cT1-T2N0 HER2+ breast cancer met inclusion criteria, including 170 (68.6%) upfront surgery patients and 85 (31.4%) who underwent NAC. The median age at diagnosis was 59 years (range, 27-90 years). Younger age, larger clinical tumor size, high-grade disease, ER-PR-HER2+ subtype, and year of diagnosis after 2019 were significantly associated with receipt of NAC (p < 0.05). In those undergoing upfront surgery, 25.3% were pN+ , including 32.5% of cT1cN0 tumors. Factors associated with nodal involvement included age under 50, larger clinical tumor size, lymphovascular invasion (LVI), multifocality/multicentricity, and abnormal lymph nodes on axillary ultrasound (p < 0.05). In subset analysis of cT1cN0 HER2+ cases, LVI remained the strongest predictor of pN + disease (73.3% vs. 22.6%, p < 0.001). Patients with cT1cN0 HER2+ breast cancer under 50 years had a 47.1% likelihood of pN+ disease.

CONCLUSION

Patients with cT1cN0 breast cancer have a 32.5% likelihood of nodal metastases, with higher incidence with younger age, LVI, multifocality/multicentricity, and abnormal axillary ultrasound. The presence of these factors may identify the patients who would benefit from treatment with neoadjuvant chemotherapy.

Predictors of nodal metastases in early stage HER2+ breast cancer: Deciding on treatment approach with neoadjuvant chemotherapy vs. upfront surgery

BACKGROUND

The purpose of this study is to evaluate preoperative predictors of nodal metastases in patients with early-stage, HER2-positive (HER2+) breast cancer.

METHODS

The SEER Database was queried to identify women with a first diagnosis of stage I-II (T1-T2) HER2-positive breast cancer treated with upfront surgery in 2018. Multivariable logistic regression was used to identify clinical characteristics independently associated with nodal involvement.

RESULTS

Overall, 3333 women with stage I-II HER2+ breast cancer met inclusion criteria and were included in the study. The median age at diagnosis was 59 years (IQR, 51-69 years). Most patients underwent breast-conserving surgery (60.9%), with a median of 3 (IQR 2-4) axillary lymph nodes removed. On final pathology, 762 (22.9%) of T1-T2 HER2+ patients were node positive; 2.7% pN0[i+], 3.7% pN1mi, 15.1% pN1, and 1.4% pN2. Women less than 40 years and those between 40 and 49 years showed the highest proportion of axillary lymph node metastasis, in 33.7% and 30.7% respectively, and declining with age (p < 0.001). Patients with triple-positive breast cancer had the highest rates of nodal involvement (24.8%), compared to 20.7% ER+/PR-/HER2+ and 19.6% of HER2-enriched patients (p = 0.006). On adjusted analysis, age, biologic subtype, tumour size, and type of surgery remained independent predictors of nodal involvement. On subgroup analysis, women under age 50 with T1c HER2-enriched or triple-positive breast cancer had a 33% and 35% incidence of nodal involvement, which declined with age.

CONCLUSIONS

The likelihood of pathologic nodal involvement in early-stage HER2+ breast cancer is contingent on age, ER/PR status, and tumour size.

Intrathecal trastuzumab versus alternate routes of delivery for HER2-targeted therapies in patients with HER2+ breast cancer leptomeningeal metastases

BACKGROUND

Patients with HER2+ breast cancer (BC) frequently develop leptomeningeal metastases (LM). While HER2-targeted therapies have demonstrated efficacy in the neoadjuvant, adjuvant, and metastatic settings, including for parenchymal brain metastases, their efficacy for patients with LM has not been studied in a randomized controlled trial. However, several single-armed prospective studies, case series and case reports have studied oral, intravenous, or intrathecally administered HER2-targeted therapy regimens for patients with HER2+ BC LM.

METHODS

We conducted a systematic review and meta-analysis of individual patient data to evaluate the efficacy of HER2-targeted therapies in HER2+ BC LM in accordance with PRISMA guidelines. Targeted therapies evaluated were trastuzumab (intrathecal or intravenous), pertuzumab, lapatinib, neratinib, tucatinib, trastuzumab-emtansine and trastuzumab-deruxtecan. The primary endpoint was overall survival (OS), with CNS-specific progression-free survival (PFS) as a secondary endpoint.

RESULTS

7780 abstracts were screened, identifying 45 publications with 208 patients, corresponding to 275 lines of HER2-targeted therapy for BC LM which met inclusion criteria. In univariable and multivariable analyses, we observed no significant difference in OS and CNS-specific PFS between intrathecal trastuzumab compared to oral or intravenous administration of HER2-targeted therapy. Anti-HER2 monoclonal antibody-based regimens did not demonstrate superiority over HER2 tyrosine kinase inhibitors. In a cohort of 15 patients, treatment with trastuzumab-deruxtecan was associated with prolonged OS compared to other HER2-targeted therapies and compared to trastuzumab-emtansine.

CONCLUSIONS

The results of this meta-analysis, comprising the limited data available, suggest that intrathecal administration of HER2-targeted therapy for patients with HER2+ BC LM confers no additional benefit over oral and/or IV treatment regimens. Although the number of patients receiving trastuzumab deruxtecan in this cohort is small, this novel agent offers promise for this patient population and requires further investigation in prospective studies.

Abstract P2-01-06: Real-world outcome and cost analysis of the addition of pertuzumab to neoadjuvant therapy in localized HER2 positive breast cancer: a single center experience

BACKGROUND: Breast cancer is the most common cancer in woman and can be classified based on the expression of hormonal receptor as well as the human epidermal growth factor receptor 2 (HER2). HER2 amplification is associated with an aggressive clinical course and higher recurrence rates following curative intend surgery. For non-metastatic T2 or node-positive HER2-positive disease neoadjuvant treatment is favored. The National Comprehensive Cancer Network (NCCN) guidelines have endorsed the use of dual HER2 blockage with trastuzumab and pertuzumab combined with chemotherapy in the neoadjuvant setting. However, pertuzumab isn’t frequently reimbursed in public health care systems for this indication. Patients who don’t achieve a pathological complete response (pCR) at surgery are eligible for adjuvant T-DM1, adding significant side effects on patients and cost on the healthcare system.

METHODS: We conducted a retrospective analysis of patients receiving anti-HER2 therapy in the neoadjuvant setting at the Jewish General hospital between 2015 and 2021. After 2019, pertuzumab was routinely added to standard neoadjuvant therapy enabling us to compare patients treated with or without dual-HER2 blockade. Our primary endpoint is the percentage of pCR at surgery. Secondary objectives are to estimate and compare the cost of anti-HER2 targeted therapy in the perioperative setting and side effect burden on patients. Statistical analyses were done using fisher exact test with statistical significance defined p value &lt; 0.05 in a one-sided test. Drug cost was calculated using publicly available resources.

RESULTS: We identified 83 patient who underwent neoadjuvant chemotherapy for HER2 amplified breast cancer. 44 patients received only trastuzumab has anti-HER2 therapy and 39 patients were treated with dual HER2 blockade containing pertuzumab. The addition of pertuzumab was associated with improved the pCR rate (67% vs. 27%; p = 0.0016). The increased pCR rate was observed in hormone-receptor positive and negative tumors. We also described a non-statistically significant trend in reduction in the requirement for axillary dissection with the use of pertuzumab (28% vs. 39%; P=0.2208). The increased in pCR rate with pertuzumab reduced the number of patients eligible for adjuvant T-DM1. If all patients with residual disease had received adjuvant T-DM1, the cost of neoadjuvant pertuzumab would be neutral, with a mean anti-HER2 drug cost of 65 150 CA$ in the pertuzumab-trastuzumab group and 66 116 CA$ in the trastuzumab group.

CONCLUSION: Our real-world analysis confirmed that neoadjuvant chemotherapy with dual HER2-blockade was well tolerated and associated with increased the pCR rate compared to regimens containing trastuzumab only. This measure is neutral on drug cost by reducing the amount of patients eligible for adjuvant T-DM1. Further research is warranted to estimate the overall health-care utilization costs of neoadjuvant pertuzumab-trastuzumab in settings where adjuvant T-DM1 is available.

Table 3: Pathologic complete response (pCR) and type of surgery in patients who received dual HER2 blockade with neoadjuvant pertuzumab-trastuzumab plus chemotherapy and in patients receiving trastuzumab only with chemotherapy at Jewish General Hospital between 2015 and 2021. ** p &lt; 0,01, ns non-statistically significant

Citation Format: Francois Panet, Matt Young, Stephanie Wong, Alice Dragomir, April A. N. Rose, Lawrence Panasci. Real-world outcome and cost analysis of the addition of pertuzumab to neoadjuvant therapy in localized HER2 positive breast cancer: a single center experience [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 P2-01-06.