Evolving perspectives on the treatment of HR+/HER2+ metastatic breast cancer

Zanidatamab plus palbociclib and fulvestrant in previously treated patients with hormone receptor-positive, HER2-positive metastatic breast cancer: primary results from a two-part, multicentre, single-arm, phase 2a study

BACKGROUND

New HER2-targeted regimens, including chemotherapy-free options, are needed for metastatic breast cancer. In an ongoing, two-part, phase 2a study, we assessed the safety and antitumour activity of zanidatamab, a HER2-targeted bispecific antibody, plus palbociclib and fulvestrant, in heavily pretreated patients with hormone receptor-positive, HER2-positive advanced or metastatic breast cancer.

METHODS

This multicentre, single-arm, two-part, phase 2a study is being conducted at 13 university hospitals, cancer centres, or research institutes in Spain, Canada, and the USA. Eligible patients were adults (aged ≥18 years) with an Eastern Cooperative Oncology Group performance status of 0 or 1, and with pathologically confirmed unresectable or metastatic breast cancer, assessed locally to be hormone receptor-positive and HER2-positive, with disease progression during or after previous HER2-targeted therapies. Patients were enrolled in part 1, part 2, or part 1 followed by part 2. In part 1, patients received starting doses of zanidatamab (20 mg/kg intravenously once every 2 weeks on days 1 and 15 of a 28-day cycle) with palbociclib (125 mg orally once a day on days 1-21 of each cycle) and fulvestrant (500 mg intramuscular injection once every 2 weeks for the first three doses [cycle 1: days 1 and 15, cycle 2: day 1], then once every 4 weeks [all subsequent cycles: day 1]). In part 1, primary endpoints were safety of the triplet combination and confirmation of recommended doses for part 2. In part 2, patients received the recommended doses confirmed in part 1, and the primary endpoint was progression-free survival at 6 months. Safety and progression-free survival were assessed in all enrolled patients who received any dose of zanidatamab, palbociclib, or fulvestrant. Patients in part 1 who were treated at the recommended doses were analysed together with the patients in part 2. This study is registered with ClinicalTrials.gov, NCT04224272, and is active with recruitment completed.

FINDINGS

Overall, 51 patients (49 [96%] female and two [4%] male; median age 54·0 [46·0-62·0] years; 42 [82%] White) were enrolled: eight in part 1 (June 10, 2020-Feb 7, 2021) and 43 in part 2 (Feb 8, 2021-Oct 31, 2022). All 51 patients had received study treatment at the data cutoff (Aug 3, 2023); median follow-up was 16·1 months (IQR 9·9-23·4) and the median duration of triplet regimen treatment was 7·4 months (3·4-14·8). The median number of previous HER2-targeted therapies was 4 (IQR 3-4). 12 (24%) of 51 patients had previously received trastuzumab deruxtecan. The planned starting drug doses administered in part 1 of the study were confirmed as the recommended doses for part 2. All 51 patients were treated at the recommended doses. All 51 patients had at least one treatment-related adverse event of any grade, with diarrhoea being the most common (41 [80%] patients, with 34 [67%] having grade 1-2 events). Grade 3 or 4 treatment-related adverse events occurred in 34 (67%) patients, with neutropenia being the most common (26 [51%] patients). One (2%) patient had a serious grade 3 treatment-related adverse event of increased transaminases. No treatment-related deaths occurred. In the overall sample (N=51), progression-free survival at 6 months was 66·7% (95% CI 52·1-79·2).

INTERPRETATION

Zanidatamab plus palbociclib and fulvestrant was generally safe and showed promising antitumour activity, supporting further evaluation of this chemotherapy-free triplet regimen.

FUNDING

Zymeworks, Jazz Pharmaceuticals, and Pfizer.

Real-World Outcomes of Pyrotinib-Based Therapy for HER2-Positive Breast Cancer With Brain Metastases: A Multicentre, Retrospective Analysis

OBJECTIVE

This study was designed to investigate the efficacy and safety of pyrotinib-based therapy for HER2-positive breast cancer with brain metastases (BM) in the real-world setting.

METHODS

Data of HER2-positive breast cancer patients with BM treated with pyrotinib-based therapy from a multicetre, registered, real-world study were analyzed.

RESULTS

Among 45 female patients, the overall objective response rate (ORR) was 62.2%, higher in 1st/2nd-line than ≥ 3rd-line (71.0% vs. 42.9%, P = .072). The objective response rate of intracranial lesions (CNS-ORR) was 71.1 %, with a significantly higher CNS-ORR observed in the 1st or 2nd-line subgroup compared to that of ≥ 3rd-line subgroup (83.9% vs. 42.9%, P < .05). By the end of follow-up, 20 patients (44.4%) died, and the 1-year survival rate was 73.3%. The median progression-free survival (PFS) was 9.1 months (95% CI 6.7-11.5). Patients with 1 or 2 BM had a longer median PFS of 12.0 months compared to 7.7 months for those with ≥ 3 BM (P = .01). In addition, 1- or 2-line therapy and full dose exposure of pyrotinib of 320mg-400mg/day were associated with improved median PFS (all P > .05). The median intracranial PFS (CNS-PFS) was 11.4 months (95% CI 7.5-15.3). However, local intervention plus systemic treatment seemed to prolong CNS-PFS compared with systemic treatment alone (13.7 vs. 9.1 months, P = .128). Diarrhea was most common (88.9%), 24.4% grade 3.

CONCLUSIONS

The pyrotinib-based therapy is effective for HER-2 positive breast cancer with BM, especially in 1st- or 2nd-line treatment, with tolerable adverse events. However, insufficient dosing of pyrotinib may impair efficacy outcomes.

The role of antibody glycosylation in autoimmune and alloimmune kidney diseases

Immunoglobulin glycosylation is a pivotal mechanism that drives the diversification of antibody functions. The composition of the IgG glycome is influenced by environmental factors, genetic traits and inflammatory contexts. Differential IgG glycosylation has been shown to intricately modulate IgG effector functions and has a role in the initiation and progression of various diseases. Analysis of IgG glycosylation is therefore a promising tool for predicting disease severity. Several autoimmune and alloimmune disorders, including critical and potentially life-threatening conditions such as systemic lupus erythematosus, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis and antibody-mediated kidney graft rejection, are driven by immunoglobulin. In certain IgG-driven kidney diseases, including primary membranous nephropathy, IgA nephropathy and lupus nephritis, particular glycome characteristics can enhance in situ complement activation and the recruitment of innate immune cells, resulting in more severe kidney damage. Hypofucosylation, hypogalactosylation and hyposialylation are the most common IgG glycosylation traits identified in these diseases. Modulating IgG glycosylation could therefore be a promising therapeutic strategy for regulating the immune mechanisms that underlie IgG-driven kidney diseases and potentially reduce the burden of immunosuppressive drugs in affected patients.

Therapeutic evolution in HR+/HER2- breast cancer: from targeted therapy to endocrine therapy

Breast cancer, a complex and varied disease, has four distinct subtypes based on estrogen receptor and human epidermal growth factor receptor 2 (HER2) levels, among which a significant subtype known as HR+/HER2-breast cancer that has spurred numerous research. The prevalence of breast cancer and breast cancer-related death are the most serious threats to women's health worldwide. Current progress in treatment strategies for HR+/HER2-breast cancer encompasses targeted therapy, endocrine therapy, genomic immunotherapy, and supplementing traditional methods like surgical resection and radiotherapy. This review article summarizes the current epidemiology of HR+/HER2-breast cancer, introduces the classification of HR+/HER2-breast cancer and the commonly used treatment methods. The mechanisms of action of various drugs, including targeted therapy drugs and endocrine hormone therapy drugs, and their potential synergistic effects are deeply discussed. In addition, clinical trials of these drugs that have been completed or are still in progress are included.