Breast cancer (BC) is the prevailing malignancy among women, with HER2 overexpression observed in 20-30 % of all BC, thereby serving as a prognostic indicator for unfavorable outcomes in affected individuals. There is a necessity to establish innovative treatment protocols to expand the therapeutic alternatives accessible for managing HER2-positive BC. In this study, we report a case of HER2-positive BC that was managed in our department using a combination of three targeted drugs (Trastuzumab, Pertuzumab and Pyrotinib) along with chemotherapy. The treatment resulted in a pathological complete response (pCR) and was observed to be well-tolerated, without any significant adverse reactions. Hence, the combination of Pyrotinib and Dual HER2 blockade treatment shows promise as a neoadjuvant therapy for locally advanced HER2-positive BC to achieve a pCR in surgery. Nevertheless, this conclusion necessitates additional validation via meticulously designed clinical research investigations encompassing larger patient populations.

Human epidermal growth factor 2 (HER2)-positive breast cancer (BC) represents nearly 20% of all breast tumors. Historically, these patients had a high rate of relapse and dismal prognosis. The advent of HER2-targeting monoclonal antibodies such as trastuzumab followed by pertuzumab had improved the prognosis of HER2-positive metastatic BC. More recently, antibody-drug conjugates (ADCs) are now reshaping the treatment paradigm of solid tumors, especially breast cancer. Tratsuzumab emtansine (T-DM1) was one of the first ADC developed in oncology and was approved for the management of HER2-positive metastatic BC. In a head-to-head comparison, trastuzumab deruxtecan (T-DXd) defeated T-DM1 as a second-line treatment. The efficacy of ADCs is counterbalanced by the appearance of acquired resistance to these agents. In this paper, we summarize the mechanisms of action and resistance of T-DM1 and T-DXd, as well as their clinical efficacy. Additionally, we also discuss potential strategies for addressing resistance to ADC.

The HER2 receptor tyrosine kinase is a member of the epidermal growth factor receptor family which includes EGFR, HER3 and HER4. They are known to play critical roles in both normal development and cancer. A subset of breast cancers is associated with the HER2 gene, which is amplified and/or overexpressed in 20-25% of invasive breast cancers and is correlated with tumor resistance to chemotherapy, Metastatic Breast Cancer (MBC) and poor patient survival. The advent of receptor tyrosine kinase inhibitors has improved the prognosis of HER2-postive breast cancers; however, HER2+MBC invariably progresses (acquired resistance or de novo resistance). The monoclonal antibody-based drugs (large molecule TKIs) target the extracellular binding domain of HER2; while the small molecule TKIs act intracellularly to inhibit proliferation and survival signals. We reviewed the modes of action of the TKIs with a view to showing which of the TKIs could be combined in nanoparticles to benefit from the power of nanotechnology (reduced toxicity, improved solubility of hydrophobic drugs, long circulation half-lives, circumventing efflux pumps and preventing capture by the reticuloendothelial system (mononuclear phagocyte system). Nanotherapeutics also mediate the synchronization of the pharmacokinetics and biodistribution of multiple drugs incorporated in the nanoparticles. Novel TKIs that are currently under investigation with or without nanoparticle delivery are mentioned, and nano-based strategies to improve their delivery are suggested. Immunotherapies currently in clinical practice, clinical trials or at the preclinical stage are discussed. However, immunotherapy only works well in relatively small subsets of patients. Combining nanomedicine with immunotherapy can boost therapeutic outcomes, by turning \"cold\" non-immunoresponsive tumors and metastases into \"hot\" immunoresponsive lesions.

We aimed to evaluate the efficacy and safety of trastuzumab emtansine in patients with metastatic breast cancer previously treated with pertuzumab plus trastuzumab and taxane. We reviewed the medical records of patients who were diagnosed with Human Epidermal Growth Factor Receptor 2 (HER-2) positive metastatic breast cancer and received pertuzumab and then TDM-1 between January 2014 and January 2021 from twenty- five cancer centers. The Kaplan- Meier method estimated progression-free survival (PFS) and overall survival (OS). Additionally, objective response rate (ORR), clinical benefit rate (CBR), and safety were evaluated. One hundred fifty-three patients were included,79.1% of the patients received TDM-1 in the second line, 90.8% had visceral metastasis, and 30.7% had central nervous system involvement. The PFS and OS of TDM-1 were evaluated according to the number of previous lines (on the 2nd line or more than two lines) metastatic sites (visceral and non-visceral) and the presence of central nervous metastasis. In TDM-1 therapy, PFS in second line therapy was ten months (95% CI: 7.7 - 12.2); this was statistically higher than later-line PFS, which was six months (95% CI: 3.3 to 8.6) (p = 0.004). The median OS time was 25 months (95% CI: 21.0 to 28.9) in patients treated with TDM-1 in the second line and 19 months (95% CI: 12.3 to 25.6) in patients who received later than the second line(p = 0.175). There were no significant differences in PFS time of patients with and without visceral and central nervous metastases. Our study showed that TDM-1 was also effective in patients using pertuzumab, contributes significantly to PFS when used in the second line compared to its use in the later line, and does not make any difference in OS.

BACKGROUND: The addition of pertuzumab (P) to trastuzumab (H) and standard chemotherapy (CT) as neoadjuvant treatment (NaT) for patients with HER2 + breast cancer (BC), has shown to increase the pathological complete response (pCR) rate, without main safety concerns. The aim of NeoPowER trial is to evaluate safety and efficacy of P + H + CT in a real-world population.
METHODS: We retrospectively reviewed the medical records of stage II-III, HER2 + BC patients treated with NaT: who received P + H + CT (neopower group) in 5 Emilia Romagna institutions were compared with an historical group who received H + CT (control group). The primary endpoint was the safety, secondary endpoints were pCR rate, DRFS and OS and their correlation to NaT and other potential variables.
RESULTS: 260 patients were included, 48% received P + H + CT, of whom 44% was given anthraciclynes as part of CT, compared to 83% in the control group. The toxicity profile was similar, excluding diarrhea more frequent in the neopower group (20% vs. 9%). Three patients experienced significant reductions in left ventricular ejection fraction (LVEF), all receiving anthracyclines. The pCR rate was 46% (P + H + CT) and 40% (H + CT) (p = 0.39). The addition of P had statistically correlation with pCR only in the patients receiving anthra-free regimens (OR = 3.05,p = 0.047). Preoperative use of anthracyclines (OR = 1.81,p = 0.03) and duration of NaT (OR = 1.18,p = 0.02) were statistically related to pCR. 12/21 distant-relapse events and 14/17 deaths occurred in the control group. Patients who achieve pCR had a significant increase in DRFS (HR = 0.23,p = 0.009).
CONCLUSIONS: Adding neoadjuvant P to H and CT is safe. With the exception of diarrhea, rate of adverse events of grade > 2 did not differ between the two groups. P did not increase the cardiotoxicity when added to H + CT, nevertheless in our population all cardiac events occurred in patients who received anthracycline-containing regimens. Not statistically significant, higher pCR rate is achievable in patients receiving neoadjuvant P + H + CT. The study did not show a statistically significant correlation between the addition of P and long-term outcomes.

UNASSIGNED: In the past few years, the combination of trastuzumab and paclitaxel has become an important option for human epidermal growth factor receptor-2 (HER2)-positive breast cancer. Small molecule tyrosine kinase inhibitors (TKIs) can bring clinical benefit to HER2-positive breast cancer patients. However, the efficacy and safety of these two regimens have not been compared. This study explored the efficacy and safety of pyrotinib combined with trastuzumab and albumin-bound paclitaxel (nab-paclitaxel).
UNASSIGNED: Patients with newly diagnosed HER2-positive early or locally advanced breast cancer treated at The Tumor Hospital of Mudanjiang City from November 2020 to June 2022 were included. The control group received pertuzumab in combination with nab-paclitaxel, whereas the pyrotinib group received pyrotinib in combination with pertuzumab and nab-paclitaxel as treatment, in a 3-week cycle for 4 cycles. The primary endpoints of this study were total pathological complete response (tpCR) rate, breast pathological complete response (bpCR) rate, and the secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and the occurrence of adverse events (AEs).
UNASSIGNED: A total of 72 patients were enrolled in the study and completed the study treatment. Baseline characteristics were well balanced between these two arms. In the control group, the tPCR rate was 23.68%, and the bpCR rate was 47.36%. In the pyrotinib group, the tPCR rate was 47.06%, and the bpCR rate was 64.71%. The tPCR rate in the pyrotinib group was significantly higher than that in the control group (P=0.049). The ORR in the pyrotinib group (67.65%) was significantly higher than that in the control group (42.11%, P=0.04 ). The median PFS (mPFS) for the control group was 9.24 months, with a mean PFS of 10.01±0.44 months [95% confidence interval (CI): 9.14-10.88 months]. In the pyrotinib group, mPFS was 9.74 months, with a mean PFS of 11.25±0.29 months (95% CI: 10.67-11.82 months). The PFS in the pyrotinib group was significantly longer than that in the control group (P=0.045). Safety results showed that the overall incidence of AEs in the control group was 68.42%, with a 3-grade adverse reaction rate of 21.05%. In the pyrotinib group, the overall incidence of AEs was 79.41%, with a 3-grade adverse reaction rate of 29.41%. The difference between the two groups was not statistically significant (P>0.05).
UNASSIGNED: Pyrotinib group in neoadjuvant treatment for HER2 positive breast cancer has obvious short-term efficacy advantages over control group. This treatment regimen can prolong PFS for 1 year, and the safety during medication is controllable. This study still has some limitations, with the relatively small sample size and relatively short follow-up period, and a further large-scale, multicenter, randomized controlled trial is necessary to verify the clinical value of this dual-target treatment regimen.

BACKGROUND: HER2-positive, estrogen receptor-positive breast cancer (HER2+, ER+ BC) is a distinct disease subtype associated with inferior response to chemotherapy plus HER2-targeted therapy compared with HER2+, ER-negative BC. Bi-directional crosstalk leads to cooperation of the HER2 and ER pathways that may drive treatment resistance; thus, simultaneous co-targeting may optimize treatment impact and survival outcomes in patients with HER2+, ER+ BC. First-line (1L) treatment for patients with HER2+ metastatic BC (mBC) is pertuzumab, trastuzumab, and taxane chemotherapy. In clinical practice, dual HER2 blockade plus a fixed number of chemotherapy cycles are given as induction therapy to maximize tumor response, with subsequent HER2-targeted maintenance treatment given as a more tolerable regimen for long-term disease control. For patients whose tumors co-express ER, maintenance endocrine therapy (ET) can be added, but uptake varies due to lack of data from randomized clinical trials investigating the superiority of maintenance ET plus dual HER2 blockade versus dual HER2 blockade alone. Giredestrant, a novel oral selective ER antagonist and degrader, shows promising clinical activity and manageable safety across phase I-II trials of patients with ER+, HER2-negative BC, with therapeutic potential in those with HER2 co-expression.
METHODS: This phase III, randomized, open-label, two-arm study aims to recruit 812 patients with HER2+, ER+  locally advanced (LA)/mBC into the induction phase (fixed-dose combination of pertuzumab and trastuzumab for subcutaneous injection [PH FDC SC] plus a taxane) to enable 730 patients to be randomized 1:1 to the maintenance phase (giredestrant plus PH FDC SC or PH FDC SC [plus optional ET]), stratified by disease site (visceral versus non-visceral), type of LA/metastatic presentation (de novo versus recurrent), best overall response to induction therapy (partial/complete response versus stable disease), and intent to give ET (yes versus no). The primary endpoint is investigator-assessed progression-free survival. Secondary endpoints include overall survival, objective response rate, clinical benefit rate, duration of response, safety, and patient-reported outcomes.
CONCLUSIONS: heredERA BC will address whether giredestrant plus dual HER2 blockade is superior to dual HER2 blockade alone, to inform the use of this combination in clinical practice for maintenance 1L treatment of patients with HER2+, ER+ LA/mBC.
BACKGROUND: ClinicalTrials.gov, NCT05296798; registered on March 25, 2022. Protocol version 3.0 (November 18, 2022).
BACKGROUND: F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124 4070, Basel, Switzerland.

OBJECTIVE: The randomized phase 2 Neo-peaks study examined usefulness of neoadjuvant trastuzumab emtansine + pertuzumab (T-DM1 + P) following docetaxel + carboplatin + trastuzumab + pertuzumab (TCbHP) as compared with the standard TCbHP regimen. We previously reported that pCR rate after neoadjuvant therapy tended to be higher with TCbHP followed by T-DM1 + P. We conducted an exploratory analysis of prognosis 5 years after surgery.
METHODS: Neoadjuvant treatment with TCbHP (6 cycles; group A), TCbHP (4 cycles) followed by T-DM1 + P (4 cycles; group B), and T-DM1 + P (4 cycles; group C, + 2 cycles in responders) were compared. Group C non-responders after 4 cycles were switched to an anthracycline-based regimen. We evaluated 5-year disease-free survival (DFS), distant DFS (DDFS), and overall survival (OS).
RESULTS: Data from 203 patients (50, 52, and 101 in groups A-C, respectively) were analyzed. No significant intergroup differences were found for DFS, DDFS, or OS. The 5-year DFS rates (95% CI) were 91.8% (79.6-96.8%), 92.3% (80.8-97.0%), and 88.0% (79.9-93.0%) in groups A-C, respectively. TCbHP followed by T-DM1 + P and T-DM1 + P with response-guided addition of anthracycline therapy resulted in similar long-term prognosis to that of TCbHP.
CONCLUSIONS: In patients who achieved pCR after neoadjuvant therapy with T-DM1 + P, omission of adjuvant anthracycline may be considered, whereas treatment should be adjusted for non-pCR patients with residual disease. T-DM1 + P with response-guided treatment adjustment may be useful for minimizing toxicity.
UNASSIGNED: UMIN-CTR, UMIN000014649, prospectively registered July 25, 2014. Some of the study results were presented as a Mini Oral session at the ESMO Breast Cancer 2023 (Berlin, Germany, 11-13 May 2023).

UNASSIGNED: The first-line treatment for human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer (MBC) involves a combination of trastuzumab, pertuzumab, and a taxane (TPH). This study assessed the efficacy of trastuzumab and pertuzumab (PH) in routine practice, following the treatment protocols of Uruguay\'s National Resources Fund (FNR), akin to clinical trials.
UNASSIGNED: Patients with advanced MBC treated with PH between 2008 and 2022 per FNR protocols were evaluated. The Kaplan-Meyer method and log-rank test were utilized for analyzing overall survival (OS). Demographic and clinical variables, including age, menopausal status, and hormone receptors (HR), were analyzed.
UNASSIGNED: The study included 318 PH-treated patients. The median age was 56 years, with 63.2% being postmenopausal and 60.4% HR and HER-2 positive. With a median follow-up of 17.2 months, the median OS was 29 months. OS varied based on HR status and the presence of metastases at different sites, significantly lower in patients with brain, cutaneous/subcutaneous, and pulmonary metastases. Additionally, OS was higher in patients treated at private institutions compared to public ones.
UNASSIGNED: This study demonstrates the disparity in oncological treatment efficacy between clinical trials and clinical reality in Uruguay, emphasizing the importance of authentic environment research for more representative and effective medicine in Latin America.

UNASSIGNED: Primary resistance to trastuzumab frequently occurs in human epidermal growth factor receptor 2 (HER2)-positive (+) breast cancer patients and remains a clinical challenge. Pyrotinib is a novel tyrosine kinase inhibitor that has shown efficacy in the treatment of HER2+ breast cancer. However, the efficacy of pyrotinib in HER2+ breast cancer with primary trastuzumab resistance is unknown.
UNASSIGNED: HER2+ breast cancer cells sensitive or primarily resistant to trastuzumab were treated with trastuzumab, pyrotinib, or the combination. Cell proliferation, migration, invasion, and HER2 downstream signal pathways were analyzed. The effects of pyrotinib plus trastuzumab and pertuzumab plus trastuzumab were compared in breast cancer cells in vitro and a xenograft mouse model with primary resistance to trastuzumab.
UNASSIGNED: Pyrotinib had a therapeutic effect on trastuzumab-sensitive HER2+ breast cancer cells by inhibiting phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) and rat sarcoma virus (RAS)/rapidly accelerated fibrosarcoma (RAF)/mitogen-activated protein kinase (MAPK)/extracellular-signal regulated kinase (ERK) pathways. In primary trastuzumab-resistant cells, pyrotinib inhibited cell growth, migration, invasion, and HER2 downstream pathways, whereas trastuzumab had no effects. The combination with trastuzumab did not show increased effects compared with pyrotinib alone. Compared with pertuzumab plus trastuzumab, pyrotinib plus trastuzumab was more effective in inhibiting cell proliferation and HER2 downstream pathways in breast cancer cells and tumor growth in a trastuzumab-resistant HER2+ breast cancer xenograft model.
UNASSIGNED: Pyrotinib-containing treatments exhibited anti-cancer effects in HER2+ breast cancer cells sensitive and with primary resistance to trastuzumab. Notably, pyrotinib plus trastuzumab was more effective than trastuzumab plus pertuzumab in inhibiting tumor growth and HER2 downstream pathways in HER2+ breast cancer with primary resistance to trastuzumab. These findings support clinical testing of the therapeutic efficacy of dual anti-HER2 treatment combining an intracellular small molecule with an extracellular antibody.