Trastuzumab-based Adjuvant Therapy Research Articles

Abstract PO1-01-06: Patterns in use and tolerance of adjuvant neratinib in patients with hormone receptor (HR)-positive, HER2-positive early-stage breast cancer

Abstract Background: In the ExteNET study, 1 year of neratinib therapy was shown to derive a significant invasive disease-free survival (iDFS) benefit in HR+, HER2+, node-positive disease after trastuzumab-based adjuvant therapy. Currently, the NCCN guidelines recommend extended adjuvant neratinib following trastuzumab-based therapy for patients (pts) with high-risk HR+ HER2+ disease. Limitations to use of neratinib include significant gastrointestinal side effects which often result in pts discontinuing treatment. In this study, we aimed to identify high-risk clinical features and characteristics of pts who were offered adjuvant neratinib therapy and factors that impacted treatment completion versus discontinuation. Methods: We performed a retrospective review of all pts with early-stage HR+ HER2+ breast cancer who were prescribed neratinib from 2017-2023 at our institution. We used the electronic medical record to extract information on patient characteristics, clinical and high-risk features. High-risk was defined as any of the following: at least 4 lymph nodes positive for disease, 1-3 lymph nodes positive for disease and a grade 3 (poorly differentiated) tumor, tumor > 5 cm, or Ki67 > 20%. Length of time on treatment, treatment holds, dose reductions and up-titrations were documented. Statistical analysis was performed using two-sided T-tests and chi-square tests. Results: We identified 62 eligible pts of whom 34 (55%) completed 1 year of neratinib and 28 (45%) did not. Median age at diagnosis was 51.5 years. 49% of pts were pre-menopausal at diagnosis, 43% were post-menopausal, 5% were peri-menopausal and 3% had undocumented menopausal status at diagnosis. Clinical features of the pts are documented in Table 1. Sixty percent of patients offered neratinib were considered high-risk at diagnosis, based on definitions described above. 73% of pts received neoadjuvant treatment with pertuzumab in addition to trastuzumab. 24 pts (39%) had residual disease and 22 pts (35%) received adjuvant T-DM1. The most common reason for neratinib discontinuation was inability to tolerate side effects (54%) followed by pill burden (18%). The most common side effect experienced by pts was diarrhea despite anti-diarrheal prophylaxis (56%), followed by rash (8%). Pts who received an up-titration of neratinib were more likely to complete the full course of neratinib when compared to those who did not (76% vs. 40.5% p = 0.013). The median starting dose of those who completed neratinib treatment was 140 mg vs. 240 mg in those who did not (p = 0.016). The median length of time on neratinib for those that did not complete the 1-year treatment course was 30 days. Neither group experienced a statistically significant greater likelihood of treatment holds or dose reductions. In terms of outcomes, 10 pts had progression of disease of whom 7 did not complete neratinib treatment (p = 0.169). Interestingly, those 7 pts developed metastatic disease and 57% had central nervous system metastases. Conclusions: Pts are more likely to complete 1 year of adjuvant neratinib with dose up-titration. Dose reductions and interruptions did not affect neratinib adherence in our patient population. Seven pts in our study developed metastatic disease, all of whom did not complete adjuvant neratinib treatment. Future prospective studies are needed to further determine the impact of adjuvant neratinib treatment on iDFS in pts who have received pertuzumab and/or T-DM1. Table 1: Clinical Features of Patients Prescribed Neratinib Citation Format: Julia Blanter, Elena Baldwin, Rima Patel, Tianxiang Sheng, Amy Tiersten. Patterns in use and tolerance of adjuvant neratinib in patients with hormone receptor (HR)-positive, HER2-positive early-stage 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 PO1-01-06.

Abstract PO5-20-02: Secondary BRain metastases prevention after Isolated intracranial progression on trastuzumab/pertuzumab or T-DM1 in pts with aDvanced human epidermal Growth factor receptor 2+ brEast cancer with addition of Tucatinib (BRIDGET)

Abstract Background: Despite treatment with trastuzumab-based therapy, up to half of patients with HER2+ advanced/metastatic breast cancer (MBC) will develop brain metastases (BrM). First-line therapy for advanced HER2+ MBC remains a taxane, trastuzumab, pertuzumab (TP) which demonstrates poor brain permeability. Isolated brain relapse with stable or absent extracranial disease remains a clinical problem in both the adjuvant (Untch et al., ESMO 2019 Congress) and metastatic settings (Noteware et al., Breast Cancer Res Treat. 2023). Current guidelines recommend continuing current systemic therapy in the setting of first isolated brain relapse following local therapy. Tucatinib, a brain-penetrable HER2-targeting tyrosine kinase inhibitor, when added to trastuzumab and capecitabine improves intracranial progression free survival (PFS) and overall survival (OS) in patients with stable or active HER2+ BrMs. We hypothesize that adding tucatinib to TP or T-DM1 in patients with HER2+ MBC with isolated brain relapse or progression could delay or prevent the development of further intracranial lesions and improve OS. Methods: BRIDGET (NCT05323955) is a single arm, phase II, multicenter study of tucatinib added to TP or T-DM1 after local therapy in patients with isolated brain relapse or progression. A total of 48 patients at 9 U.S. sites as part of the Hoosier Cancer Research Network (HCRN) with metastatic HER2+ breast cancer will be enrolled after 1st or 2nd BrM relapse or progression within 8 weeks of local therapy. Patients must currently be receiving standard of care treatment with TP or T-DM1 in the metastatic setting, or adjuvant trastuzumab-based or T-DM1 therapy with isolated brain recurrence. Extracranial disease must be stable per RECISTv1.1 or absent. Patients may not have leptomeningeal disease or untreated brain lesions over 5 mm. Patients will receive continuous tucatinib added to their current therapy (TP or T-DM1). The primary objective is intracranial PFS compared to a historical control (H0: PFS < 5 months (mos), HA: PFS > 8 mos) of the HER2CLIMB clinical trial where patients could continue on trial with isolated brain progression. In these patients, median time from brain progression to second progression or death was 7.6 mos (95% CI, 3.9 to 11.3 mos) in the tucatinib arm versus 3.1 mos (95% CI, 1.2 to 4.1 mos) in the control arm (Lin et al., J Clin Onc 2020). Secondary endpoints include PFS by RECISTv1.1, PFS of extracranial disease, locally treated versus new distant intracranial metastasis PFS, site of first progression (brain versus non-brain), OS, and toxicity in patients with BrM. Collection of correlative specimens including archival tissue, cerebrospinal fluid (optional), whole blood for ctDNA are planned. Patient-reported outcomes surveyed utilizing the FACT-BR and FACIT-Fatigue questionnaires are also included for future analyses. As of 7/06/23, accrual is 5 patients of the anticipated 48 patients overall, across 5 sites (Duke University, Dana Farber Cancer Institute, Ohio State University, Providence Portland Medical Center, and Washington University in St. Louis) currently open. An additional 4 sites are pending opening. Those interested in this trial can reach out to the study Principal Investigators, Carey Anders, MD (carey.anders@duke.edu) or Sarah Sammons, MD (sarahl_sammons@dfci.harvard.edu). Citation Format: Sarah Sammons, Amanda Van Swearingen, Laura Noteware, Nusayba Bagegni, Kelly Moulton, Stevie Threatt, Denise Jaggers, Shannon Shea, Eric Lipp, Erin Riley, Sin-Ho Jung, Gloria Broadwater, Masey Ross, Kimberly Strickland, Sasha Beyer, Alison Conlin, Aki Morikawa, Rashmi Murthy, Carey Anders. Secondary BRain metastases prevention after Isolated intracranial progression on trastuzumab/pertuzumab or T-DM1 in pts with aDvanced human epidermal Growth factor receptor 2+ brEast cancer with addition of Tucatinib (BRIDGET) [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 PO5-20-02.

Optimising Extended Adjuvant Neratinib Use in HER2+/HR+ Early Breast Cancer: Memo for Nurses

Neratinib (NERLYNX®) is indicated for the extended adjuvant treatment of adult patients with early-stage HR+/HER2-overexpressed/amplified breast cancer, who completed adjuvant trastuzumab-based therapy <1 year ago. This infographic offers valuable guidance to nurses in effectively managing neratinib patients to ensure they reap the maximum advantages from this therapy.

Novel quantitative immunohistochemistry method using histone H3, family 3B as the internal reference standard for measuring human epidermal growth factor receptor 2 expression in breast cancer.

Immunohistochemistry (IHC) is an essential technique in surgical and clinical pathology for detecting diagnostic, prognostic, and predictive biomarkers for personalized cancer therapy. However, the lack of standardization and reference controls results in poor reproducibility, and a reliable tool for IHC quantification is urgently required. The objective of this study was to describe a novel approach in which H3F3B (histone H3, family 3B) can be used as an internal reference standard to quantify protein expression levels using IHC. The authors enrolled 89 patients who had human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC). They used a novel IHC-based assay to measure protein expression using H3F3B as the internal reference standard. H3F3B was uniformly expressed at the protein level in all tumor regions in cancer tissues. HER2 expression levels were measured with the H-score using HALO software. Kaplan-Meier analysis indicated that, among patients who had HER2-positive BC in The Cancer Genome Atlas data set and the authors' data set, the subgroup with low HER2 expression had a significantly better prognosis than the subgroup with high HER2 expression. Furthermore, the authors observed that HER2 expression levels were precisely evaluated using the proposed method, which can classify patients who are at higher risk of HER2-positive BC to receive trastuzumab-based adjuvant therapy. Dual-color IHC with H3F3B is an excellent tool for internal and external quality control of HER2 expression assays. The proposed IHC-based quantification method accurately assesses HER2 expression levels and provides insights for predicting clinical prognosis in patients with HER2-positive BC who receive trastuzumab-based adjuvant therapy.

Neratinib as Extended Adjuvant Treatment of HER2-Positive/HR-Positive Early Breast Cancer Patients in Germany, Austria, and Switzerland: Interim Results of the Prospective, Observational ELEANOR Study

Introduction: Prognosis of patients diagnosed with HER2+ early breast cancer (eBC) has substantially improved, but distant recurrences impacting quality of life and survival still occur. One treatment option for extended adjuvant treatment of patients with HER2+/HR+ eBC is neratinib, available in Europe for patients who completed adjuvant trastuzumab-based therapy within 1 year. The ELEANOR study is investigating the real-world use of neratinib in Germany, Austria, and Switzerland. Results from an interim analysis of the first 200 patients observed for ≥3 months are reported. Methods: The primary objective of this prospective, multicenter, observational study is to assess patient adherence to neratinib (defined as the percentage of patients taking neratinib on ≥75% prescribed days). Secondary objectives are patient characteristics and treatment outcomes. Results: At cut-off (May 2, 2022), a total of 202 patients had been observed for ≥3 months, with neratinib treatment documented for 187 patients (median age: 53.0 years; 67.9% at increased risk of disease recurrence). In total, 151 (80.7%) patients had received prior neoadjuvant treatment; of these, 82 (54.3%) patients achieved a pathologically complete response. Neratinib was initiated at a median 3.6 months after trastuzumab-based treatment, with 36.4% starting at a dose <240 mg/day. Treatment is ongoing for 46.0% of patients, with median treatment duration of 11.2 (interquartile range 0.9–12.0) months. Diarrhea was the most common adverse event (78.6% any grade, 20.3% grade ≥3); pharmacologic prophylaxis was used in 85.6% of patients. Conclusions: The pattern of anti-HER2 pretreatment observed reflected the current treatment for HER2+/HR+ eBC in Germany, Austria, and Switzerland. These interim results suggest that neratinib as an extended adjuvant is a feasible option after various anti-HER2 pretreatments and that its tolerability can be managed and improved with proactive diarrhea management.

TIPS-19 TRIAL IN PROGRESS: SECONDARY BRAIN METASTASES PREVENTION AFTER ISOLATED INTRACRANIAL PROGRESSION ON TRASTUZUMAB/PERTUZUMAB OR T-DM1 IN PATIENTS WITH ADVANCED HUMAN EPIDERMAL GROWTH FACTOR RECEPTOR 2+ BREAST CANCER WITH THE ADDITION OF TUCATINIB (BRIDGET)

Abstract Despite trastuzumab-based therapy, up to half of patients with HER2+ metastatic breast cancer (MBC) will develop brain metastases (BrM). First-line therapy for HER2+ MBC, taxane/trastuzumab/pertuzumab (TP), demonstrates poor brain permeability. Isolated brain relapse with stable/absent extracranial disease remains a clinical problem in both the adjuvant and metastatic settings, and current guidelines recommend continuing current systemic therapy following local therapy. Tucatinib, a brain-penetrable HER2-inhibitor, when added to trastuzumab and capecitabine improves intracranial PFS and OS in patients with stable/active HER2+ BrMs. We hypothesize that adding tucatinib to TP or T-DM1 in patients with HER2+ MBC with isolated brain relapse or progression could delay or prevent the development of further intracranial lesions and improve OS. BRIDGET (NCT05323955) is a single arm, phase II study of tucatinib added to TP or T-DM1 after local therapy in patients with isolated brain relapse or progression. A total of 48 patients at 9 U.S. sites through HCRN with HER2+ MBC will be enrolled after 1st or 2nd BrM relapse/progression within 8 weeks of local therapy. Patients must currently be receiving TP or T-DM1 in the metastatic setting, or adjuvant trastuzumab-based or T-DM1 therapy with isolated brain recurrence. Extracranial disease must be stable per RECISTv1.1 or absent. Patients will receive tucatinib added to their current therapy. The primary objective is intracranial PFS compared to a historical control (H0: historical iPFS &amp;lt;5 months (mos), HA: iPFS &amp;gt;8 mos) of the HER2CLIMB trial. In these patients, median time from brain progression to second progression/death was 7.6 mos with tucatinib versus 3.1 mos in the control arm. Secondary endpoints include PFS by RECISTv1.1, PFS of extracranial disease, locally treated versus new distant intracranial metastasis PFS, site of first progression, OS, and toxicity. Collection of correlative specimens and patient-reported outcomes (FACT-BR, FACIT-Fatigue) are also included.

Frequent upregulation of HER2 protein in hormone-receptor-positive HER2-negative breast cancer after short-term neoadjuvant endocrine therapy.

Endocrine resistant metastatic disease develops in ~ 20-25% of hormone-receptor-positive (HR+) breast cancer (BC) patients despite endocrine therapy (ET) use. Upregulation of HER family receptor tyrosine kinases (RTKs) represent escape mechanisms in response to ET in some HR+ tumors. Short-term neoadjuvant ET (NET) offers the opportunity to identify early endocrine escape mechanisms initiated in individual tumors. This was a single arm, interventional phase II clinical trial evaluating 4weeks (± 1week) of NET in patients with early-stage HR+/HER2-negative (HER2-) BC. The primary objective was to assess NET-induced changes in HER1-4 proteins by immunohistochemistry (IHC) score. Protein upregulation was defined as an increase of ≥ 1 in IHC score following NET. Thirty-seven patients with cT1-T3, cN0, HR+/HER2- BC were enrolled. In 35 patients with evaluable tumor HER protein after NET, HER2 was upregulated in 48.6% (17/35; p = 0.025), with HER2-positive status (IHC 3+ or FISH-amplified) detected in three patients at surgery, who were recommended adjuvant trastuzumab-based therapy. Downregulation of HER3 and/or HER4 protein was detected in 54.2% of tumors, whereas HER1 protein remained low and unchanged in all cases. While no significant volumetric reduction was detected radiographically after short-term NET, significant reduction in tumor proliferation rates were observed. No significant associations were identified between any clinicopathologic covariates and changes in HER1-4 protein expression on multivariable analysis. Short-term NET frequently and preferentially upregulates HER2 over other HER family RTKs in early-stage HR+/HER2- BC and may be a promising strategy to identify tumors that utilize HER2 as an early endocrine escape pathway. Trial registration number: NCT03219476.

P004 Pyrotinib after trastuzumab-based adjuvant therapy in patients with HER2-positive breast cancer : a multicenter, open-label, phase 2 trial

P004 Pyrotinib after trastuzumab-based adjuvant therapy in patients with HER2-positive breast cancer : a multicenter, open-label, phase 2 trial

Prognostic Value Of Tumor Infiltrating Lymphocytes Among HER-2+ Breast Cancer Patients Receiving Trastuzumab-Based Adjuvant Therapy

Background: Tumor Infiltrating Lymphocytes (TILs) have prognostic value on HER2 positive breast cancer (BC). The absence of standardized method for evaluating TILs causes variations in results of previous studies. This study is performed to evaluate the prognostic value of TILs in HER2 positive BC treated with trastuzumab-based adjuvant therapy using standardized method recommended by the International TILs Working Group.&#x0D; Aim: To analyze the prognostic value of TILs in HER2 positive BC patients receiving trastuzumab-based adjuvant therapy at Dr. Sardjito General Hospital, Yogyakarta and to analyze proportion differences between high TILs (≥30%) and low TILs (&lt;30%).&#x0D; Methods: This is a retropective cohort study on HER2 positive, stage 1-3 BC patients who received trastuzumab-based adjuvant therapy. Histopathology slides from 6 hospitals/laboratoriums were analyzed by two pathologists.&#x0D; Results: 73 data were available for analysis. TILs stroma &lt;30% was 65,8% and most patients received combination of anthracyclines, taxanes and trastuzumab (67,1%). There was no difference of overall survival between high and low TILs (p log rank: 0,331).&#x0D; Conclusion: HER2 positive BC with high TILs did not show better overall survival compared to those with low TILs. The proportion of HER2 positive breast cancer with high TILs was lower than those with low TILs.

Abstract OT2-14-01: Pyrotinib after trastuzumab-based adjuvant therapy in high-risk early human epidermal growth factor receptor 2-positive breast cancer: a multicenter phase 2 trial

Abstract Objective: Trastuzumab-based adjuvant therapy was demonstrated to improve the prognosis of early human epidermal growth factor receptor 2 (HER-2) positive breast cancer, while about 10% of patients showed primary resistance. ExteNET study showed that 1 year of neratinib, an irreversible pan-HER tyrosine kinase inhibitor, after trastuzumab-based adjuvant therapy significantly improved invasive disease-free survival (iDFS) in women with HER2-positive breast cancer. Besides, for patients with early hormone receptor positive breast cancer within 1 year of prior trastuzumab with residual disease after neoadjuvant therapy, extended adjuvant neratinib showed prolonged overall survival, which suggested the potential benefit of extended adjuvant therapy for high-risk patients. Pyrotinib is an oral irreversible pan-HER receptor tyrosine kinase inhibitor targeting epidermal growth factor receptor, HER2, and HER4, which showed promising efficacy and manageable safety profiles in the treatment of HER-2 positive advanced breast cancer. In this study, we aimed to evaluate the efficacy and safety of extended adjuvant pyrotinib following trastuzumab-based adjuvant therapy in patients with high-risk early HER-2 positive breast cancer. Methods: In this ongoing multicenter, open-label, phase II trial at 23 centers in China, women with operable high-risk early HER-2 positive breast cancer and known hormone receptor status, who have completed trastuzumab-based adjuvant therapy within 6 months were enrolled. High-risk patients must meet one of the following criteria: N stage ≥1; T stage ≥2; did not achieve pathological complete response (pCR) after neoadjuvant therapy; had pCR after neoadjuvant therapy but with tumor size ≥ 5cm or N stage ≥2; or tumor size less than 2cm but with high Ki67, histologic grade 3 or with lymph node micrometastasis. Eligible patients were assigned to receive 6 month or 1 year of oral pyrotinib 400mg/day. The primary endpoint was the 2-year iDFS rate. Results: Between January, 2019 and February, 2022, a total of 142 eligible women were enrolled and assigned to receive pyrotinib, with a median age of 50 (range: 25-72) years old. Ninety-seven patients had a T stage ≥2. A total of 108 patients (76.1%) had node-positive disease, and 64 (45.1%) were hormone receptor positive. Twenty-five patients used neoadjuvant therapy previously, and all of them did not receive pCR (Table 1). After a median follow-up of 20 (range: 0.25-41) months, the 2-year iDFS rate was not available. Two and four patients reported invasive disease events after 6-month and 1-year of follow-up, with the 6-month and 1-year iDFS rates of 98.6% and 97.2%, respectively. The most common adverse events reported was diarrhea (78.2%), followed by fatigue (36.6%), lymphocyte count decreased (36.6%), nausea (33.1%) and hand-foot syndrome (33.1%). Forty-three patients experienced grade 3 diarrhea, and no grade 4 or higher adverse event was reported (Table 2). Adverse event leading to treatment discontinuation occurred in 12 (8.5%) patients. Conclusion: Extended adjuvant pyrotinib administrated after trastuzumab-based adjuvant therapy was well-tolerated and showed potential efficacy in high-risk early HER-2 positive breast cancer. The follow-up is ongoing to determine the long-term benefit of extended adjuvant pyrotinib. Table 1. Baseline characteristics of patients ER: estrogen receptor; PR: progesterone receptor. Table 2. Treatment-emergent adverse event occurring in at least 10% of the patients Citation Format: Feilin Cao, Zhaosheng Ma, Guinv Hu, Xiaotao Zhu, Shuguang Li, Shuzheng Chen, Binglie Chen, Zhanwen Li, Weizhu Wu, Xiaochun Ji, Jingde Shu, Deyou Tao, Xiaoqing Hu, Min Zheng, Ouchen Wang, Qingjing Feng, Jing Hao, Xujun Li. Pyrotinib after trastuzumab-based adjuvant therapy in high-risk early human epidermal growth factor receptor 2-positive breast cancer: a multicenter phase 2 trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-14-01.

Abstract P2-01-01: Interim analysis (n=200) from ELEANOR: a multi-national, prospective, non-interventional study among patients with HER2+ and HR+ early breast cancer treated with extended adjuvant neratinib in the clinical routine

Abstract Background Recent advances in the treatment of human epidermal growth factor receptor positive (HER2+) early breast cancer (eBC) have led to a reduction in recurrence risk; still a relevant percentage of patients relapses over time, predominantly presenting with distant recurrence. Neratinib is registered in Europe as extended adjuvant treatment for adult patients with HER2+, hormone receptor positive (HR+) eBC, who completed adjuvant trastuzumab-based therapy within one year prior to start of neratinib. In the ExteNET study, neratinib improved the absolute 5-year invasive disease-free survival (iDFS) rate by 5.1% versus placebo in this population (90.8% vs. 85.7%; HR 0.58 [95% CI 0.41-0.82]), mainly by reducing the rate of distant metastases. According to explorative analyses from ExteNET, the effect may be even more pronounced in patients with non-pCR after neoadjuvant trastuzumab treatment and/or in patients completing the full duration of neratinib therapy (i.e. ≥11 months of neratinib treatment). Diarrhea, the most common grade 3 adverse event (neratinib: 39% without primary diarrhea prophylaxis, median cumulative duration 5 days; placebo: 1%; no grade 4 events) can generally be managed through adequate prophylaxis and treatment management. ELEANOR is the first non-interventional study (NIS) of real-world use of neratinib and its management in eBC patients in Germany, Austria and Switzerland. Methods Enrollment of 300 adult female patients with HER2+/HR+ eBC is planned in accordance with the SmPC specifications. Primary endpoint is the rate of patients adherent to neratinib treatment (i.e. neratinib use for ≥75% of treatment days). Secondary objectives include characterization of patients scheduled to receive neratinib, details on neratinib treatment, recurrences, safety/tolerability, and health-related quality of life (HRQoL). CANKADO, an eHealth application developed to support patient/physician communication, is an integral part of the NIS. Here, we report results of the preplanned interim analysis based on 200 enrolled patients. Results At data cut-off (May 2022), 202 patients had been observed for 3 months; patient enrollment is ongoing. Median age was 53.0 years and 66.3% of patients were at increased risk of disease recurrence (defined as non-pCR or AJCC stage &amp;gt; I). Most patients had received prior neoadjuvant treatment (79.7%). Post-neoadjuvant treatment included dual HER2 blockade with trastuzumab and pertuzumab (38.8%/23.9% of pCR/non-pCR patients) and trastuzumab-emtansine (T-DM1, 53.5% of non-pCR patients). Neratinib treatment had been documented for 187 patients, treatment was ongoing for 46.0% of patients. Diarrhea was the most common adverse event (78.6% any grade, 19.3% grade 3, 2 patients grade 4), but was markedly lower when indirectly compared to ExteNET (39% grade 3). The neratinib dose escalation schedule was chosen for 36.4% of patients and led to a decreased incidence of severe diarrhea (16.2% grade 3, no grade 4 events). 93.9% (95% CI: 87.9-97.5%) of 115 evaluable patients adhered to neratinib treatment. Conclusion The results of this preplanned interim analysis reflect the current treatment landscape in Germany, Austria and Switzerland. These results confirm, in line with the observed adherence data, that extended adjuvant neratinib use is feasible in typical clinical practice settings. Furthermore, treatment management strategies such as diarrhea prophylaxis or neratinib dose escalation are routinely used and can increase treatment tolerability markedly. The study is funded by Pierre Fabre Pharma GmbH (Freiburg, Germany), Pierre Fabre Pharma Austria (Wels, Austria) and Pierre Fabre Pharma AG (Allschwil, Switzerland). Citation Format: Rupert Bartsch, Nadia Harbeck, Denise Wrobel, Matthias Zaiss, Jürgen Terhaag, Dagmar Guth, Andrea Distelrath, Rachel Wuerstlein, Mark-Oliver Zahn, Diana Lüftner, Michael Schwitter, Marija Balic, Christian Jackisch, Volkmar Müller, Gabriel Rinnerthaler, Marcus Schmidt, Khalil Zaman, Timo Schinköthe, Anna Resch, Urs Breitenstein. Interim analysis (n=200) from ELEANOR: a multi-national, prospective, non-interventional study among patients with HER2+ and HR+ early breast cancer treated with extended adjuvant neratinib in the clinical routine [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 P2-01-01.

Overall survival with neratinib after trastuzumab-based adjuvant therapy in HER2-positive breast cancer (ExteNET): A randomised, double-blind, placebo-controlled, phase 3 trial

BackgroundExteNET showed that neratinib, an irreversible pan-HER tyrosine kinase inhibitor, given for 1 year after trastuzumab-based therapy significantly improved invasive disease-free survival in women with early-stage HER2-positive breast cancer. We report the final analysis of overall survival in ExteNET. MethodsIn this international, randomised, double-blind, placebo-controlled, phase 3 trial, women aged 18 years or older with stage 1–3c (amended to stage 2–3c) HER2-positive breast cancer who had completed neoadjuvant and adjuvant chemotherapy plus trastuzumab were eligible. Patients were randomly assigned to oral neratinib 240 mg/day or placebo for 1 year. Randomisation was stratified according to hormone receptor (HR) status (HR-positive vs. HR-negative), nodal status (0, 1–3 or 4+), and trastuzumab regimen (sequentially vs. concurrently with chemotherapy). Overall survival was analysed by intention to treat. ExteNET is registered (Clinicaltrials.gov: NCT00878709) and is complete. ResultsBetween July 9, 2009, and October 24, 2011, 2840 women received neratinib (n = 1420) or placebo (n = 1420). After a median follow-up of 8.1 (IQR, 7.0–8.8) years, 127 patients (8.9%) in the neratinib group and 137 patients (9.6%) in the placebo group in the intention-to-treat population had died. Eight-year overall survival rates were 90.1% (95% CI 88.3–91.6) with neratinib and 90.2% (95% CI 88.4–91.7) with placebo (stratified hazard ratio 0.95; 95% CI 0.75–1.21; p = 0.6914). ConclusionsOverall survival in the extended adjuvant setting was comparable for neratinib and placebo after a median follow-up of 8.1 years in women with early-stage HER2-positive breast cancer.

Final findings from the CONTROL trial: Strategies to reduce the incidence and severity of neratinib-associated diarrhea in patients with HER2-positive early-stage breast cancer

BackgroundNeratinib is an irreversible pan-HER tyrosine kinase inhibitor approved for HER2-positive early-stage and metastatic breast cancer. Diarrhea is the most frequent side effect and the most common reason for early discontinuation. The phase II CONTROL trial investigated antidiarrheal prophylaxis or neratinib dose escalation (DE) for prevention of diarrhea. We present complete study results including final data for two DE strategies. MethodsPatients who completed trastuzumab-based adjuvant therapy received neratinib 240 mg/day for 1 year. Early cohorts investigated mandatory prophylaxis with loperamide, then additional budesonide or colestipol. Final cohorts assessed neratinib DE over the first 2 (DE1) or 4 weeks (DE2). The primary endpoint was incidence of grade ≥3 diarrhea. Health-related quality of life (HRQoL) was assessed using FACT-B and EQ-5D-5L. Results563 patients were enrolled into six cohorts. All strategies reduced grade ≥3 diarrhea with the lowest incidence in DE1 (DE1 13%; colestipol + loperamide [CL] 21%, DE2 27%; budesonide + loperamide [BL] 28%; loperamide [L] 31%; colestipol + loperamide as needed [CL-PRN] 33%). Diarrhea-related discontinuations occurred early and were lowest in DE1 (DE1 3%; CL 4%; DE2 6%; CL-PRN 8%; BL 11%; L 20%). More patients stayed on neratinib for the prescribed period versus historical controls. Prior pertuzumab use did not affect rates of grade ≥3 diarrhea, diarrhea-related discontinuations, or treatment duration. Early transient reductions in HRQoL scores were observed. ConclusionsThese complete results from CONTROL show improved neratinib tolerability with proactive management at the start of therapy. Two-week neratinib DE with loperamide as needed was particularly effective. ClinicalTrials.gov registration numberNCT02400476.

75P Interim analysis (n=150) of the multi-national, prospective, non-interventional ELEANOR study observing real-life extended adjuvant treatment with neratinib in patients with HER2+ / HR+ early breast cancer (eBC)

Neratinib is registered in Europe as extended adjuvant treatment for adult patients with Human Epidermal Growth Factor Receptor 2-positive (HER2+) and Hormone receptor-positive (HR+) eBC within one year after completed adjuvant trastuzumab-based therapy (“EMA-/Swiss-label” population). In the ExteNET trial, extended adjuvant neratinib improved the absolute 5-year invasive disease-free survival rate by 5.1% vs. placebo in this population (90.8% vs. 85.7%; HR 0.58 [95% CI 0.41-0.82]). More pronounced benefit was observed in patients with non-pCR after neoadjuvant trastuzumab-based therapy and/or in patients who completed one year of neratinib (descriptive post-hoc analyses).

Abstract P5-18-02: Final findings from the CONTROL trial of diarrheal prophylaxis or neratinib dose escalation on neratinib-associated diarrhea and tolerability in patients with HER2+ early-stage breast cancer

Abstract Background: Neratinib (NERLYNX®), an irreversible pan-HER tyrosine kinase inhibitor, is approved for the extended adjuvant treatment of early-stage HER2+ breast cancer following adjuvant trastuzumab-based therapy and in combination with capecitabine for HER2+ metastatic breast cancer. Diarrhea is the most frequently reported on-target side effect associated with neratinib; in the ExteNET adjuvant trial, where no mandatory anti-diarrheal prophylaxis was used, 39.8% of patients reported grade 3 diarrhea and 16.8% of patients discontinued neratinib due to diarrhea. The CONTROL trial (Clinicaltrials.gov: NCT02400476) was designed to investigate pre-emptive antidiarrheal prophylaxis (loperamide alone or in combination with budesonide or colestipol) or neratinib dose escalation (DE) for the prevention of neratinib-associated diarrhea. Data for the loperamide, budesonide and colestipol cohorts have been reported previously [Barcenas et al. Ann Oncol 2020]. The final findings for the two DE regimen cohorts are reported here. Methods: CONTROL is an international, multi-cohort, open-label, phase 2 study. Patients ≥18 years of age with stage I-IIIc HER2+ breast cancer received oral neratinib (240 mg/day for 1 year) after trastuzumab-based adjuvant therapy. Patients were enrolled sequentially into separate cohorts investigating: 1) mandatory loperamide prophylaxis; 2) budesonide + loperamide; 3) colestipol + loperamide; 4) colestipol + loperamide PRN; 5) neratinib DE + loperamide PRN (two cohorts). DE1 schedule: neratinib 120 mg/day for week 1, 160 mg/day for week 2, then 240 mg/day from week 3 onwards to complete 12 months of treatment. DE2 schedule: neratinib 160 mg/day for weeks 1&amp;2, 200 mg/day for weeks 3&amp;4, then 240 mg/day from week 5 onwards up to 12 months. Both DE cohorts included loperamide PRN. Adverse events were graded according to NCI-CTCAE v4.0. Primary endpoint: incidence of grade ≥3 diarrhea. Results: A total of 563 patients were enrolled in CONTROL. All preventive strategies reduced the incidence of grade 3 diarrhea compared with that seen in ExteNET (historical control: 39.8%). Median cumulative duration of grade 3 diarrhea ranged from 2-3.5 days across the CONTROL study cohorts for the entire 12-month treatment period (compared with 5.0 days for ExteNET). The proportion of patients discontinuing neratinib because of diarrhea was decreased in all cohorts compared with ExteNET (16.8%), except for loperamide alone. Adoption of neratinib DE, particularly the 2-week DE schedule (DE1), most markedly reduced the incidence, severity, and duration of neratinib-associated diarrhea in CONTROL compared with ExteNET (see Table). Conclusions: Neratinib DE + loperamide PRN during the first 2 weeks of treatment (DE1 cohort) was associated with the lowest rates of grade 3 diarrhea (13.3%) and diarrhea-related discontinuations (3.3%) compared with all other anti-diarrheal strategies investigated in CONTROL. These final findings from the study show improved tolerability of neratinib with all diarrhea prophylaxis strategies and suggest that neratinib DE1 with loperamide PRN allows patients to stay on treatment longer and receive the full benefit of neratinib therapy. Table. Patient disposition and diarrhea characteristics: ExteNET vs CONTROL DE cohortsExteNET(n=1408)CONTROL DE1 (n=60)CONTROL DE2 (n=62)Patients completing 1 year of neratinib treatment, %617874Median duration of treatment, months (range)11.6 (2.5–11.9)12.0 (0.2–12.4)11.9 (0.3–14.5)Diarrhea, %Grade 339.813.327.4Grade 4&amp;lt;100Median cumulative duration of grade 3 diarrhea,a days52.52Discontinuations due to diarrhea, %16.83.36.5Dose reductions due to diarrhea, %26311Dose holds due to diarrhea, %341213aNo grade 4 diarrhea was reported in CONTROL. Citation Format: Arlene Chan, Manuel Ruiz-Borrego, Gavin Marx, Adam Brufsky, Jo Chien, Michael Thirlwell, Maureen Trudeau, Ron Bose, José A García-Sáenz, Daniel Egle, Barbara Pistilli, Johanna Wassermann, Kerry A Cheong, Christian F Singer, Daniel Hunt, Navid Foruzan, Leanne McCulloch, Carlos H Barcenas. Final findings from the CONTROL trial of diarrheal prophylaxis or neratinib dose escalation on neratinib-associated diarrhea and tolerability in patients with HER2+ early-stage 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 P5-18-02.

Abstract P2-13-21: Improved central nervous system outcomes in patients with early-stage HER2-positive breast cancer who receive neratinib for the recommended duration: Findings from the phase 3 ExteNET trial

Abstract Background: Non-adherence or early discontinuation from systemic adjuvant therapy is associated with an increased risk of disease recurrence and mortality. In the phase 3 ExteNET trial, neratinib (NERLYNX®), an oral irreversible pan-HER tyrosine kinase inhibitor, significantly improved invasive disease-free survival (iDFS) when given for 12 months in patients with early-stage HER2-positive (HER2+) breast cancer after trastuzumab-based therapy. Anti-diarrheal prophylaxis was not mandated by protocol and 17% of patients discontinued neratinib early because of diarrhea. Improved iDFS, distant disease-free survival, and overall survival (OS) have since been reported in patients who completed the planned duration of neratinib therapy compared with all randomized patients [ASCO 2021]. Here we assess central nervous system disease-free survival (CNS-DFS) in 3 discrete groups of patients who completed planned therapy with neratinib in ExteNET: intent-to-treat (ITT) population; patients with hormone receptor-positive disease who initiated neratinib within 1 year after prior trastuzumab (HR+/≤1 year, the population for which neratinib is approved in the EU); and HR+/≤1 year with residual disease post-neoadjuvant therapy (i.e. no pathologic complete response [pCR]). Methods: Patients with early-stage HER2+ breast cancer received oral neratinib 240 mg/day or placebo after trastuzumab-based (neo)adjuvant therapy for 12 months. Patients who completed neratinib therapy (defined as treatment duration ≥11 months or cessation of neratinib if recurrence occurred prior to 11 months) were compared with placebo (all randomized patients). CNS-DFS was defined as time from randomization to any CNS recurrence or death from any cause (exploratory endpoint). Kaplan-Meier methods were used to estimate CNS-DFS and OS rates. Hazard ratios (HR) with 95% confidence intervals (CI) for neratinib versus placebo were estimated using a Cox proportional hazards model. Data cutoffs: March 2017 (CNS-DFS); July 2019 (OS); median follow-up 8.0 (range 0-9.8) years. Results: 2840 patients were included in the ITT population (1420 per group). Among patients who completed neratinib therapy, CNS-DFS was improved versus placebo in each of the 3 patient groups (see Table). For CNS-DFS, the magnitude of effect of neratinib versus placebo was consistently greater in patients who completed neratinib therapy than in the corresponding overall randomized patient group: ITT HR, 0.70 vs 0.73; HR+/≤1 year HR, 0.27 vs 0.41; HR+/≤ 1 year no pCR HR: 0.16 vs 0.24, respectively. Conclusions: These descriptive findings suggest that, in addition to improved OS, patients who receive the recommended 12-month course of neratinib may have improved CNS outcomes. A dose-escalation strategy, which was shown to improve the tolerability of neratinib, decrease the proportion of patients who discontinue treatment due to diarrhea (3.3%), and allow more patients to stay on treatment for 11 months or longer in the CONTROL trial (NCT02400476) compared with ExteNET, may help to realize these benefits in the real-world setting. Table: CNS-DFS and OS in patients who completed planned therapy with neratinib (ITT, HR+/≤1 year and HR+/≤1 year no pCR)NCNS-DFS rate (5 years)OS rateaPopulation/group NeratinibPlaceboDifference, %bHR (95% CI)Difference, %bHR (95% CI)ITT14201420+1.10.73 (0.45-1.17)-0.10.95 (0.75-1.21)cCompleted therapyd8721420+1.20.70 (0.40-1.19)+2.00.78 (0.58-1.04)HR+/≤1 yeare670664+2.70.41 (0.18-0.85)+2.10.79 (0.55-1.13)Completed therapyd402664+3.20.27 (0.08-0.69)+5.80.49 (0.29-0.78)HR+/≤1 yearb no pCRf131164+6.40.24 (0.04-0.92)+9.10.47 (0.23-0.92)Completed therapyd92164+6.90.16 (0.01-0.81)+13.20.29 (0.10-0.68)aOS analysis after a median follow-up of 8.0 (range 0-9.8) years; bDifference (neratinib vs placebo); cStratified by randomization stratification factors; dDefined as ≥11 months of therapy or ended treatment due to disease recurrence (neratinib arm), and all randomized subjects (placebo arm); eHR+ and ≤1 year after prior trastuzumab; fResidual disease post-neoadjuvant therapy. Abbreviations: CI, confidence interval; CNS-DFS, central nervous system disease-free survival; HR, hazard ratio; HR+, hormone receptor-positive; OS, overall survival; pCR, pathologic complete response. Citation Format: Frankie Ann Holmes, Debra Patt, Yvonne Manalo, Julie C Smith, Steven W Papish, Noa Efrat, Ana Arance, Bo Zhang, Deepa Lalla, Alvin Wong, Miguel Martin. Improved central nervous system outcomes in patients with early-stage HER2-positive breast cancer who receive neratinib for the recommended duration: Findings from the phase 3 ExteNET 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 P2-13-21.

Abstract P2-13-30: First interim analysis from ELEANOR: A multi-national, prospective, non-interventional study (NIS) in patients with human epidermal growth factor receptor positive (HER2+) early breast cancer observing real-life extended adjuvant treatment with neratinib

Abstract Background: Recent advances in (post-)/(neo)adjuvant treatment for HER2+ breast cancer have led to a major reduction in recurrence risk; still a relevant percentage of patients relapses over time, predominantly presenting with distant recurrence. Neratinib is registered in Europe as extended adjuvant treatment for adult patients with HER2+, HR+ early-stage breast cancer (eBC), who completed adjuvant trastuzumab-based therapy less than one year ago. In the ExteNET study, neratinib improved the 5-year iDFS absolute-rate by 5.1% versus placebo in this population (90.8% vs. 85.7%; HR 0.58 [95% CI 0.41-0.82]), mainly by prolonging time to development of distant metastases. According to explorative (post-hoc) analyses from ExteNET, the effect might be even more pronounced in patients with non-pCR after neoadjuvant trastuzumab treatment and/or in patients with completion of neratinib therapy (i.e. ≥11 months of neratinib treatment). Diarrhea, the most common grade 3 adverse event (neratinib: 39% without primary diarrhea prophylaxis, median cumulative duration 5 days; placebo: 1%; no grade 4 events) can generally be managed through adequate prophylaxis and treatment management. ELEANOR is the first international NIS to investigate real-world use of neratinib and its treatment management in eBC patients in Germany, Austria and Switzerland. Methods: The primary objective of this ongoing NIS is to investigate the rate of patients being adherent to neratinib treatment (i.e. neratinib intake for ≥75% of treatment days). Secondary objectives include detailed patient and disease characteristics, details on prior trastuzumab-based therapies (including pertuzumab and T-DM1), neratinib doses, dose modifications and neratinib treatment management, relapses, safety/tolerability, and quality of life (QoL), among others. 300 adult female patients with HER2+/HR+ eBC are planned in accordance with the SmPC specifications (planned end of documentation: 2023). CANKADO, an application developed to support patient/physician communication, is an integral part of the NIS. Different CANKADO modules can be used optionally, including QoL documentation (EQ-5D-5L- and diarrhea-specific questionnaires) and continuous documentation of health status and symptoms. Results: Between July 2020 and July 2021, 141 patients have been enrolled; patient enrollment is ongoing. The first pre-planned interim analysis will be performed after the 100th patient has been observed for 3 months (data cut July 2021). Here, we will present baseline demographic and tumor characteristics for the first 100 patients, as well as prior trastuzumab-based treatments and first safety and tolerability data of real-world neratinib use. Conclusion: The results of the first interim analysis present a preliminary snapshot of the current treatment landscape and real-life neratinib use in Germany and Austria. The ELEANOR NIS should help to understand adherence to neratinib treatment and use of extended adjuvant HER2-targeted therapy in the current treatment landscape focussing on treatment management after different pre-therapies. The study is funded by Pierre Fabre Pharma GmbH (Freiburg, Germany), Pierre Fabre Pharma Austria (Wels, Austria) and Pierre Fabre Pharma AG (Allschwil, Switzerland). Citation Format: Diana Lüftner, Rupert Bartsch, Urs Breitenstein, Marija Balic, Christian Jackisch, Volkmar Müller, Gabriel Rinnerthaler, Marcus Schmidt, Michael Schwitter, Khalil Zaman, Denise Wrobel, Dagmar Guth, Jürgen Terhaag, Matthias Zaiss, Timo Schinköthe, Nadia Harbeck. First interim analysis from ELEANOR: A multi-national, prospective, non-interventional study (NIS) in patients with human epidermal growth factor receptor positive (HER2+) early breast cancer observing real-life extended adjuvant treatment with neratinib [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 P2-13-30.

P14.42 Neratinib for treatment of leptomeningeal metastases from HER2-positive breast cancer in extended access program: preliminary results

Abstract BACKGROUND Leptomeningeal metastases (LM) occur in 5% of human epidermal growth factor receptor 2 (HER2) breast cancer (BC) with a poor overall survival (OS) of 3 months. Neratinib is an oral, irreversible tyrosine kinase pan-inhibitor that was approved by FDA for the treatment of HER2-enriched BC, who completed a prior adjuvant trastuzumab-based therapy. The aim of the study was to evaluate the activity of neratinib in LM from HER2-positive BC after the failure of multiple lines of treatment, including trastuzumab. PATIENTS AND METHODS Inclusion criteria were as follows: age ≥ 18 years; histological diagnosis of primary HER2-positive BC; newly-diagnosed LM according to LANO criteria; KPS ≥60 at the time of diagnosis of LM; coexistence of BM that have or not received WBRT or radiosurgery; systemic disease with a life expectancy of at least 3 months; concomitant drugs, including capecitabine, trastuzumab, TDM-1, pertuzumab, and hormone therapy were allowed, with the exclusion of lapatinib or other investigational agents. Neratinib was administered 240 mg daily continuously. The primary endpoint was the OS after the diagnosis of LM. Secondary endpoints were progression-free survival (PFS) following the diagnosis of LM, neurological benefit, radiological response rate, and tolerability. RESULTS From January 2018 to April 2021, 9 patients with LM have been enrolled. Median age at the time of diagnosis of LM was 44 years (95%CI 36–59) with a median KPS of 80 (95%CI 60–90). Median time since LM onset from the diagnosis of primary BC was 42 months (95%CI 11–166), and patients underwent a median number of adjuvant treatments before LM of 3 (95%CI 2–5). Three patients developed LM alone, and other 6 had LM associated with multiple brain metastases. Six-months and 1-year OS were 66.7% and 22.3%, respectively, with a median OS of 8 months (95%CI 3–13*). Median PFS was 3.5 months (95%CI 2–6) after the start of treatment. A neurological improvement was reported in 2/9 patients (22.2%), while in other 4/9 patients (44.5%) was achieved a neurological stabilization lasting for a median time of 5 months (95%CI 2–19). The best radiological response was a stable disease in 5/9 patients (55.6%), while no complete or partial response were achieved according to LANO and RANO criteria, respectively. A CSF clearance was observed in 1 patient only (11.1%) following two months of neratinib. Grade III-IV adverse events were not reported, and 2 patients only (22.2%) had mild diarrhea correlated with neratinib. CONCLUSION This is the first study that shows that neratinib might be a safe and effective treatment in LM from heavily pretreated HER2-positive BC.

200TiP ELEANOR: A multi-national, prospective, non-interventional study (NIS) in patients with human epidermal growth factor receptor (HER2) positive, early breast cancer (eBC) observing real-life extended adjuvant treatment with neratinib and concurrent use of the eHealth solution CANKADO

The aim of (post-)/(neo)adjuvant chemotherapy and HER2-targeted therapy in HER2+ eBC is to prevent locoregional recurrences and development of distant metastases. Despite significant improvements of long-term clinical outcomes, (late) recurrences are still frequently observed with longer follow-up. Neratinib is an irreversible pan-HER tyrosine kinase inhibitor registered in Europe as extended adjuvant treatment for patients with HR-positive (HR+), HER2+ eBC who completed adjuvant trastuzumab-based therapy ≤1 year before starting neratinib (EMA-/Swissmedic-label” population).

How to Optimise Extended Adjuvant Treatment with Neratinib for Patients with Early HER2+ Breast Cancer.

Over the last 20 years, treatment of patients with human epidermal growth factor receptor 2-positive (HER2+) early breast cancer has considerably improved. The development and addition of (neo)adjuvant trastuzumab to chemotherapy in patients with early HER2+ breast cancer (EHBC) has been shown to provide improvements in both disease-free survival (DFS) and overall survival, with some patients having a good prognosis being candidates for chemotherapy de-escalation strategies. However, despite such promising clinical outcomes, a significant proportion of patients still recur calling for the development of new preventive approaches. To this aim, the use of (neo)adjuvant trastuzumab for longer than one year or followed by lapatinib were tested without additional clinical improvement. Based on more recent advances, therapeutic strategies for patients with HER2+ tumours are now incorporating the use of newer (neo)adjuvant treatments, such as pertuzumab and trastuzumab emtansine, which have shown to further improve the invasive DFS (iDFS) benefit gained with trastuzumab. In this context, the tyrosine kinase inhibitor neratinib is approved in Europe for the extended adjuvant treatment of adult patients with early-stage hormone receptor-positive HER2+ breast cancer who completed adjuvant trastuzumab-based therapy less than one year ago. Clinical data have demonstrated that neratinib significantly improves iDFS when used for the total recommended duration of 12 months. This review paper provides an overview of the treatment of patients with EHBC, with a focus on the post-trastuzumab use of neratinib.