Loss of HER2-positivity following neoadjuvant targeted therapy for breast cancer is not associated with inferior oncologic outcomes

Prognostic significance of HER2 loss after HER2-targeted neoadjuvant treatment in patients with HER2-positive locally advanced breast cancer

Loss of human epidermal growth factor receptor 2 (HER2) expression can be seen in almost 25-30 % patients after HER2 receptor directed neoadjuvant treatment. These patients have unclear clinical outcomes in previous studies. We aimed to investigate the importance of HER2 loss, additionally with predictive factors for the loss of HER2. This was a retrospective and multicenter study that included 272 HER2-positive BC patients with no pathological complete response who received neoadjuvant chemotherapy plus HER2-targeted treatments. The factors that may affect the loss of HER2 detected by immunohistochemistry(IHC) and the association with survival were analyzed.The rate of HER2 loss after neoadjuvant treatments(NAT) was 27.9 % (n = 76). Disease recurrence was observed in 18(23.7 %) patients with HER2 loss, while it was detected in 62 (31.7 %) patients without HER2 loss(p = 0.23). Pre and post-NAT ER status, and post-NAT ki-67 status had a significant impact on disease-free survival(DFS) (p = 0.0012, p = 0.004, and p = 0.04, respectively).There were no significant association between DFS and loss of HER2 (p = 0.64) and dual anti-HER2 blockade (p = 0.21). Pre-NAT clinical stage (HR:1.65 p = 0.013), post-NAT LN status (HR:3.18, p = 0.02) and pre-NAT ER status (HR:0.24, p = 0.041) were significant independent prognostic factors for DFS while post-NAT residual disease in axillar tissue was an independent prognostic factor for OS (HR:1.54 p = 0.019). Moreover, age (<40 years vs ≥40 years) (p = 0.031) and tumor grade (p = 0.004) were predictive factors for HER2 loss. Our results showed that HER2 loss did not affect survivals. However, young age and being high grade tumor may predict HER2 loss.

Prognostic impact of reduced HER2 protein expression in post-neoadjuvant therapy resection specimens: A single institution experience and review of the literature

BACKGROUND

Retesting for Human epidermal growth factor receptor-2 (HER2) in post-neoadjuvant therapy resection is variable, and data is conflicting regarding the prognostic significance of changes in HER2 expression pre and post therapy.

METHODS

We identified 104 patients with localized HER2 IHC 3+ breast cancer who received neoadjuvant trastuzumab(T)/pertuzumab(P) containing chemotherapy at Yale Cancer Center between 2012 and 2022. Patients were divided into 3 cohorts by response and HER2 IHC in the residual disease: Cohort 1 pathologic complete response (pCR), Cohort 2 pre-treatment IHC 3+/post treatment IHC 1+/2+, and Cohort 3 pre-treatment IHC 3+/post-treatment IHC 3+. Kaplan-Meier survival analysis was performed to assess recurrence free survival at 36 months.

RESULTS

The overall pCR rate was 62.5% (65/104), while 37.5% (39/104) of patients had residual disease (RD). Among patients with RD, 58.9% (23/39) remained IHC 3+ and 41.1% (16/39) had reduced HER2 expression IHC1+ or 2+. In patients with HER2 IHC 3+ RD, 26% (6/23) developed local recurrence or distant metastasis while none of patients with post NAT HER2 IHC 1+ or 2+ RD had relapse (p = 0.0309). In patients with pCR, 6.15% (4/65) had recurrence. Kaplan-Meier survival analysis revealed superior disease-free survival in patients with reduced HER2 IHC expression compared to those with remained IHC 3+ (log rank p = 0.004).

CONCLUSION

We conclude that reduced HER2 expression by IHC following neoadjuvant treatment was associated with lower recurrence rates in HER2 IHC 3+ breast cancer. If confirmed, RD HER2 IHC expression could be used as a prognostic biomarker to stratify patients in adjuvant trials and identify patients who may benefit from more intensive adjuvant therapy and post therapy surveillance.

Risk-Based Therapeutic Strategies for HER2-Positive Early Breast Cancer: A Consensus Paper

Breast cancer represents the most commonly diagnosed neoplasm worldwide and the HER2-positive subtype accounts for nearly 1 in 5 breast cancers. The majority of patients with breast cancer present with an early-stage disease upon diagnosis, which is thus susceptible to virtually curative treatment strategies. For a stage, I T1a/b N0 HER2-positive disease, upfront surgery followed by adjuvant therapy is the preferred approach. However, there is some uncertainty regarding the appropriate management of stage cT1c cN0, as both the neoadjuvant approach and upfront surgery have been proven to be feasible therapeutic options. The aim of this Delphi consensus was to define the best strategies for the treatment of early HER2-positive breast cancer. This work may help clinicians in the management of early HER2-positive breast cancer.

Changes in HER2 status and survival outcomes in patients with non-pathological complete response after neoadjuvant targeted treatment

To study the changes in human epidermal growth factor receptor 2 (HER2) expression in patients with HER2-positive breast cancer before and after neoadjuvant treatment. The clinicopathologic data of 499 patients with HER2-positive breast cancer who completed neoadjuvant treatment and surgery at the Fourth Hospital of Hebei Medical University from 2018 to 2021 were retrospectively analyzed. According to the new adjuvant regimen, 298 patients were divided into the trastuzumab + pertuzumab combined chemotherapy group (dual target group), and 201 patients were divided into the trastuzumab combined chemotherapy group (single target group).The effect of different neoadjuvant regimens on HER2 status was analyzed by comparing HER2 expression before and after treatment. A total of 255 of 499 neoadjuvant patients with HER2-positive breast cancer achieved a pathological complete response (pCR). pCR was achieved in 60.07% (179/298) of the dual target group and 37.81% (76/201) of the single target group, and the difference was statistically significant (χ² = 23.795, P < .001). Among 244 cases of HER2-positive breast cancer that did not reach pCR (non-pCR), there was a certain negative conversion rate of HER2 expression after neoadjuvant treatment, and the overall negative conversion rate was 13.11% (32/244). The negative conversion rates of the dual target group was 17.65% (21/119) and single target group was 8.80% (11/125), (χ² = 4.188, P = .041). The DFS of 499 patients in the pCR group was 98.43% (251/255), which was significantly higher than that in the non-pCR group 92.21% (225/244), (χ² = 8.536, P = .003). Only 2 (0.20%) of 32 patients with negative HER2 had recurrence and metastasis. Neoadjuvant treatment had an effect on the expression status of HER2, especially in the dual target group. For patients with negative HER2, the optimal treatment strategy remains to be explored, but continued anti-HER2 treatment is still recommended.

Genomics of ERBB2-Positive Breast Cancer in Young Women Before and After Exposure to Chemotherapy Plus Trastuzumab

PURPOSE

Erb-B2 receptor tyrosine kinase 2 (ERBB2)-positive breast cancer (BC) is particularly common in young women. Genomic features of ERBB2-positive tumors before and after chemotherapy and trastuzumab (chemo + H) have not been described in young women and are important for guiding study of therapeutic resistance in this population.

METHODS

From a large prospective cohort of women age 40 years or younger with BC, we identified patients with ERBB2-positive BC and tumor tissue available before and after chemo + H. Whole-exome sequencing (WES) was performed on each tumor and on germline DNA from blood. Tumor-normal pairs were analyzed for mutations and copy number (CN) changes.

RESULTS

Twenty-two women had successful WES on samples from at least one time point; 12 of these had paired sequencing results from before and after chemo + H and 10 had successful sequencing from either time point. TP53 was the only significantly recurrently mutated gene in both pre- and post-treatment samples. MYC gene amplification was observed in four post-treatment tumors. Seven of 12 patients with paired samples showed acquired and/or clonally enriched alterations in cancer-related genes. One patient had an increased clonality putative activating mutation in ERBB2. Another patient acquired a clonal hotspot mutation in TP53. Other genomic changes acquired in post-treatment specimens included alterations in NOTCH2, STIL, PIK3CA, and GATA3. There was no significant change in median ERBB2 CN (20.3 v 22.6; Wilcoxon P = .79) between paired samples.

CONCLUSION

ERBB2-positive BCs in young women displayed substantial genomic evolution after treatment with chemo + H. Approximately half of patients with paired samples demonstrated acquired and/or clonally enriched genomic changes in cancer genes. ERBB2 CN changes were uncommon. We identified several genes warranting exploration as potential mechanisms of resistance to therapy in this population.

Loss of HER2 in breast cancer: biological mechanisms and technical pitfalls

Loss of HER2 in previously HER2-positive breast tumors is not rare, occurring in up to 50% of breast cancers; however, clinical research and practice underestimate this issue. Many studies have reported the loss of HER2 after neoadjuvant therapy and at metastatic relapse and identified clinicopathological variables more frequently associated with this event. Nevertheless, the biological mechanisms underlying HER2 loss are still poorly understood. HER2 downregulation, intratumoral heterogeneity, clonal selection, and true subtype switch have been suggested as potential causes of HER2 loss, but translational studies specifically investigating the biology behind HER2 loss are virtually absent. On the other side, technical pitfalls may justify HER2 loss in some of these samples. The best treatment strategy for patients with HER2 loss is currently unknown. Considering the prevalence of this phenomenon and its apparent correlation with worse outcomes, we believe that correlative studies specifically addressing HER2 loss are warranted.

Factors influencing HER2 discordance in nonmetastatic breast cancer and the role of neoadjuvant therapy

Objective: The rates of and the factors influencing HER2 discordance in patients receiving neoadjuvant therapy for breast cancer are investigated. Methods: This study retrospectively examines the rates of HER2 and hormone receptor discordance between the biopsy and postoperative resection specimens of 400 female early-stage breast cancer patients. Results: One hundred and thirty-three (33.3%) patients had received neoadjuvant therapy. The rate of HER2 discordance between biopsy and resection specimens was 1.7% in the control group and 5.3% in the neoadjuvant therapy group (p = 0.018). The rate of HER2 discordance was higher in younger patients and in patients with T1 tumors in the neoadjuvant therapy group. Conclusion: Neoadjuvant therapy, age <40 years and smaller tumor size were independent risk factors for HER2 discordance.

Androgen Receptor: A New Marker to Predict Pathological Complete Response in HER2-Positive Breast Cancer Patients Treated with Trastuzumab Plus Pertuzumab Neoadjuvant Therapy

(1) Background: Neoadjuvant therapy is the main therapeutic strategy for human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients, and the combination of trastuzumab and pertuzumab (HP) has become a routine treatment. How to predict and screen patients who are less likely to respond to neoadjuvant therapy is the focus of research. The androgen receptor (AR) is a biomarker that is widely expressed in all breast cancer subtypes and is probably related to treatment response and prognosis. In this study, we investigated the relationship between AR expression and treatment response in HER2-positive breast cancer patients treated with HP neoadjuvant therapy. (2) Methods: We evaluated early breast cancer patients treated with HP neoadjuvant therapy from Jan. 2019 to Oct. 2020 at Peking University First Hospital Breast Cancer Center. The inclusion criteria were as follows: early HER2-positive breast cancer patients diagnosed by core needle biopsy who underwent both HP neoadjuvant therapy and surgery. We compared the clinical and pathological features between pathological complete response (pCR) and non-pCR patients. (3) Results: We included 44 patients. A total of 90.9% of patients received neoadjuvant therapy of taxanes, carboplatin, trastuzumab and pertuzumab (TCHP), and the total pCR rate was 50%. pCR was negatively related to estrogen receptor (ER) positivity (OR 0.075 [95% confidence interval (CI) 0.008–0.678], p = 0.021) and positively related to high expression levels of AR (OR 33.145 [95% CI 2.803–391.900], p = 0.005). We drew a receiver operating characteristic (ROC) curve to assess the predictive value of AR expression for pCR, and the area under the curve was 0.737 (95% CI 0.585–0.889, p = 0.007). The optimal cutoff of AR for predicting pCR was 85%. (4) Conclusion: AR is a potential marker for the prediction of pCR in HER2-positive breast cancer patients treated with HP neoadjuvant therapy.