Prognostic and predictive factors for the efficacy and safety of trastuzumab deruxtecan in HER2-positive gastric or gastroesophageal junction cancer.

BACKGROUND: Trastuzumab deruxtecan (T-DXd) is an antibody-drug conjugate targeting HER2-positive gastric cancer or gastroesophageal junction cancer (GC/GEJC). Although effective, T-DXd has notable toxicities, including interstitial lung disease (ILD). This study evaluated the efficacy, safety, and prognostic factors associated with T-DXd for GC/GEJC. METHODS: A retrospective observational study was conducted at our institution by reviewing medical records of patients treated with T-DXd until September 2023. Eligible patients had unresectable advanced or recurrent GC/GEJC, HER2 status of IHC 3 + or IHC 2 + /ISH-positive, and prior treatment with trastuzumab-containing regimen. RESULTS: Among the 101 patients analyzed, the initial T-DXd dose was 6.4 mg/kg in 77 patients and 5.4 mg/kg in 24 patients. The objective response rate was 54.3%, with a median PFS of 5.4 months and a median OS of 11.4 months. The significant prognostic factors for shorter PFS and OS included ECOG PS ≥ 1, presence of primary lesion, and peritoneal metastasis but not the initial T-DXd dose. ILD occurred in 14.9% of patients. Notably, higher T-DXd dose and smaller tumor burden were associated with a higher incidence of ILD. CONCLUSIONS: Several factors were associated with prognosis after T-DXd treatment in patients with GC/GEJC. Tumor burden is a potential risk factor for T-DXd-related ILD. Further studies are needed to optimize dosing based on tumor burden and to improve the therapeutic index.

Impaired cyclin D3 protein degradation contributes to trastuzumab resistance in HER2 positive breast cancer.

As the first anti-HER2 targeted agent approved by FDA in 1998, Trastuzumab has significantly improved the outcome of patients with HER2 positive metastatic breast cancer. Unfortunately, resistance to trastuzumab is a severe obstacle to its therapeutic efficacy in clinical application, and its mechanism has not yet been fully elucidated. In our study, we found that stabilization of cyclin D3 could be one reason for trastuzumab resistance. Trastuzumab could induce G1/G0 phase arrest by downregulating cyclin D3 protein expression. However, the protein expression of cyclin D3 was not affected in trastuzumab-resistant cells, which might be related to aberrant activation of ERK signaling pathway. Furthermore, degradation of cyclin D3 protein by trastuzumab was mainly resulted from ubiquitin-dependent proteasome mechanism instead of transcriptional regulation. In trastuzumab-resistant breast cancer cells, trastuzumab-induced degradation of cyclin D3 protein was abrogated. When the ubiquitin pathway was inhibited, cells would show a predisposition to resistance to trastuzumab. Further, CDK4/6 inhibitor can inhibit the proliferation of trastuzumab-resistant HER-2 positive breast cancer cells. Therefore, combination of CDK4/6 inhibitors and anti-HER2 targeted therapy may be an alternative and promising strategy to overcome trastuzumab resistance in the future.

Severe thrombocytopaenia caused by trastuzumab emtansine in a patient with breast cancer: A case report.

We present the case of a 48-year-old woman with human epidermal growth factor receptor 2- and hormone receptor-positive left early breast cancer who developed severe thrombocytopaenia and moderate liver dysfunction after administration of trastuzumab emtansine as an adjuvant therapy. Briefly, she experienced grade 2 subcutaneous bleeding, decreased platelet count (18,000/µL), and elevated aspartate aminotransferase/alanine aminotransferase levels (254/193 IU), resulting in admission to the emergency room. Although thrombocytopaenia is a well-known adverse event associated with trastuzumab emtansine, we observed it immediately after trastuzumab emtansine administration in our patient. Based on the literature survey, we hypothesised that trastuzumab emtansine may have affected mature platelets in our patient. In addition, moderate hepatotoxicity may be partially explained based on the pharmacological mechanisms of trastuzumab emtansine action involving microtubule disorganisation in hepatocytes via cytoskeleton-associated protein 5 on the cell surface by emtansine. We discuss the mechanism of the development of thrombocytopaenia and liver dysfunction.

Uptake of biosimilars in China: a retrospective analysis of the case of trastuzumab from 2018 to 2023.

BACKGROUND: The Chinese biosimilar industry has demonstrated rapid growth in recent years. Limited evidence is available about biosimilar uptake at the national level. This study aimed to assess biosimilar uptake in the case of trastuzumab and to explore potential factors influencing the biosimilar penetration at national and provincial levels. METHODS: This study employed an interrupted time series analysis to assess the level and trend changes of national trastuzumab originator consumption and the overall trastuzumab consumption after the price reduction of the originator and the introduction of the first biosimilar using the China Hospital Pharmacy Audit procurement data from March 2018 to February 2023. A latent class trajectory model (LCTM) was also adopted to estimate the biosimilar penetration across 30 provincial-level administrative divisions (PLADs). Based on the LCTM grouping results, provincial characteristics were analyzed. RESULTS: After rapid growth, the penetration of biosimilars demonstrated a moderate ascending trend at the national level, reaching 27% in February 2023. Following the introduction of the first biosimilar in July 2021, the consumption of the originator decreased by 0.5% per month (P = 0.008), and the growth rate of overall trastuzumab consumption decreased by 1.1% per month (P = 0.014). LCTM fit the best when the number of trajectory classes was two, dividing 30 PLADs into a group demonstrating a faster increase in biosimilar penetration and the other with a slower increase. The PLADs in the fast-increasing group had a higher proportion of the population covered by the national basic health insurance, a lower proportion of the urban population, a lower proportion of the population covered by the urban employee health insurance program, a lower gross domestic product per capita, a lower total health expenditure per capita, and a lower out-of-pocket expenditure. CONCLUSIONS: The uptake of trastuzumab biosimilars in China was lower compared with major European countries. The introduction of trastuzumab biosimilars presented a substitutional effect. Perceptions of physicians and patients, the medicines procurement model, competition from other biologics, and health insurance payment methods may influence biosimilar uptake. Enhancing a comprehensive understanding of biosimilars among physicians and patients, including biologics with biosimilars in the national pooled procurement, and implementing provider payment reforms could foster biosimilar penetration.

Impact of low HER2 expression on response to CDK4/6 inhibitor treatment in advanced HR + /HER2- breast cancer: a multicenter real-world data analysis.

PURPOSE: CDK4/6 inhibitors (CDK4/6i) represent the first-line therapy approach of choice for patients with hormone receptor-positive, HER2-negative advanced breast cancer (HR + /HER-ABC). Approximately 50% of HR + /HER2-ABC displays low HER2 expression (HER2 low). Recent data emerging from the DESTINY-Breast04 trial demonstrated practice-changing efficacy of the antibody-drug conjugate trastuzumab deruxtecan (T-DXd) in patients with low HER2 expression. Here, we aimed to analyze the impact of low HER2 expression on CDK4/6i therapy response in a well-characterized multicenter HR + /HER-ABC cohort. METHODS: Patients diagnosed with HR + /HER2-ABC who were treated with CDK4/6i in clinical routine between November 2016 and December 2020 at four certified German Breast Cancer Centers were retrospectively identified. The cohort was stratified according to graduation of positivity in HER2 immunohistochemistry (IHC; HER2 zero = IHC score 0 and HER2 low = IHC score 1 + , 2 + /fluorescence in situ hybridization negative). Subgroups were analyzed with regard to progression-free survival (PFS) following CDK4/6i initiation. FINDINGS: The study cohort comprised n = 448 patients. For n = 311 patients, HER2 status from the metastatic site was available. n = 91 (29.3%) cases were HER2 zero and n = 220 cases (70.7%) were HER2 low. There was no significant difference in PFS between the two groups (PFS: 17 months versus 18 months, log-rank p = 0.42). Further, we examined the influence of HER2 expression changes between primary and metastatic tissue (n = 171; HER2 gain/HER2 loss/HER2 stable expression) on CDK4/6i treatment response. Again, there was no significant difference between these three groups, respectively (PFS: 16 months versus 13 months versus 17 months, log-rank p = 0.86). CONCLUSIONS: In our analysis, HER2 status did not have a significant impact on treatment response to CDK4/6i.

Long-Term Survival in Human Epidermal Growth Factor Receptor 2-Positive Bone-Only Metastatic Breast Cancer: Trastuzumab, Denosumab, and Potential Synergistic Effects.

Breast cancer is the second most common cancer worldwide. There are four main subtypes of breast cancer, one of which involves positivity for human epidermal growth factor receptor 2 (HER2). Here, we present a case series of unusually long survival in three patients with HER2-positive metastatic breast cancer. All cases involved post-menopausal women with bone-only metastases undergoing treatment with the HER2-targeted therapy trastuzumab and the receptor activator of nuclear factor kappa-Β ligand (RANK-L) inhibitor denosumab. Our three patients survived for 17, 13, and 11 years, respectively, from the time of metastasis. The patients who survived for 17 and 13 years both presented with metastatic disease at diagnosis, while the patient who survived for 11 years with metastatic disease was known to have non-metastatic breast cancer for four years prior. We also report the development of foot fractures from minor trauma, as low as walking, despite a bone density reported as normal in the patient with 17 years of treatment. These unusually long survival times and the unusual location of the fractures are questioned to be secondary to the long duration of treatment with HER2-targeted therapy and RANK-L inhibitor therapy. Our case series is the first to describe the use of trastuzumab and denosumab in HER2-positive metastatic breast cancer. All three reported cases had no clinical or radiographic disease progression at the time of reporting. Furthermore, our case of survival for 17 years represents the longest survival time reported yet, raising the possibility of a synergistic relationship between RANK-L inhibitors and HER2-targeted therapy in the long-term control of HER2-positive metastatic breast cancer. This manuscript discusses evidence from primary studies on HER2 and receptor activator of nuclear factor kappa-Β (RANK) signalling and drug responses and hypothesizes on possible mechanisms of synergism. Given that treatment of HER2-positive breast cancer has historically not involved RANK-L inhibition, this study may outline future areas of research in improving treatment algorithms, especially for bone-only metastatic disease.

A recombinant fragment antigen-binding (Fab) of trastuzumab displays low cytotoxic profile in adult human cardiomyocytes: first evidence and the key implication of FcγRIIA receptor.

Fragment crystallizable gamma receptors (FcγRs) mediate various cellular responses with significant cardiovascular implications. They contribute to the anticancer activity of trastuzumab (TRZ), a recombinant humanized monoclonal antibody that interferes with human epidermal growth factor receptor 2 (HER2), thereby blocking its physiological function in cardiac cells. This is responsible for cardiac complications that hamper TRZ clinical application. In this study we investigated the involvement of FcγRs in the TRZ cardiotoxicity. We used a recombinant antigen-binding fragment (Fab) of TRZ (rFab-HER2) to examine whether the absence of the Fc region resulted in fewer cardiomyocyte toxicity while preserving TRZ's ability to inhibit HER2. When exposed to rFab-HER2, AC16 human adult ventricular cardiomyocytes were less vulnerable to damage and death, than to TRZ. Specifically, TRZ exhibited cytotoxicity at a lower concentration (150 µg/mL, corresponding to ~1 µM) compared to rFab-HER2 (250 µg/mL, corresponding to ~5 µM). Like TRZ, rFab-HER2 negatively modulated HER2 levels in cardiomyocyte (without inducing cytotoxic activity in BJ human fibroblast cells that either did not express or express very low levels of HER2) and inhibited the downstream ERK/AKT cascades. But rFab-HER2 did not alter cardiomyocyte mitochondrial dynamic balance, and affect apoptosis and inflammation, while it limited cytosolic and mitochondrial ROS indicators. On contrary, the Fc region (50-250 µg/mL) exerted direct cytotoxic action on cardiomyocytes (but not on human fibroblasts that lacked Fc receptors). TRZ (150 µg/mL) markedly upregulated the expression level of FcγRIIA (a FcγRs strongly involved in TRZ-induced antibody-dependent cellular toxicity) in cardiomyocytes, whereas the Fab fragment (150 µg/mL) had no effect. Our results demonstrate that Fc region plays an important pathogenic role in TRZ-induced cardiomyocyte toxicity. In addition, targeting FcγRIIA might contribute to the off-target effects of TRZ therapy.

Predictors of trastuzumab-induced cardiotoxicity among racially and ethnically diverse patients with HER2-positive breast cancer.

BACKGROUND: While trastuzumab has been shown to improve disease-free and overall survival in patients with HER2-positive breast cancer, it may also cause trastuzumab-induced cardiotoxicity (TIC). Although racial and ethnic minorities are at higher risk for cardiovascular disease (CVD) compared to non-Hispanic Whites (NHW), limited data exists on TIC incidence in diverse multi-ethnic populations. Our objective was to assess racial and ethnic differences in TIC and left ventricular ejection fraction (LVEF) recovery among patients with HER2-positive breast cancer. METHODS: We conducted a retrospective cohort study including patients diagnosed with stage I-III HER2-positive breast cancer between 2007 and 2022 who had received adjuvant trastuzumab. We analyzed associations between sociodemographic factors, tumor characteristics, treatment regimens, and CVD risk factors with the primary outcomes of TIC and LVEF recovery, using multivariable logistic regression models. TIC was defined as > 10% decrease in LVEF to an overall LVEF < 50%; LVEF recovery as a return to a LVEF > 50%. RESULTS: Among 496 evaluable patients, median age was 53 years (IQR: 45.0-62.0) with 36.6% NHW, 15.8% non-Hispanic Black (NHB), 27.8% Hispanic, and 19.8% Other. Fifty-three (10.6%) patients developed TIC, half of whom experienced LVEF recovery. Compared to NHW, NHB had a higher rate of TIC (9.3% vs. 17.7%, respectively) and lower rate of LVEF recovery (70.6% vs. 21.4%, respectively), however, race/ethnicity was not a significant predictor of TIC after adjusting for confounders. Increasing age, lower baseline LVEF, anthracycline use, and presence of hypertension or coronary artery disease were significantly associated with TIC in multivariable analysis. CONCLUSIONS: TIC was more common among NHB compared to NHW, however, Black race was not consistently associated with TIC after adjustment for CVD risk factors. This suggests that CVD comorbidities (e.g., hypertension) that more frequently affect racial and ethnic minorities and are modifiable may explain differences in TIC incidence and recovery.

A 14-year retrospective of HER2 + metastatic breast cancer treatment at one comprehensive cancer center: Impact of the trastuzumab/pertuzumab and trastuzumab-emtansine sequence versus trastuzumab on overall survival.

Introduction: Monoclonal antibodies represent a significant improvement in the treatment of the HER2 + metastatic cancer, which is associated with a worse prognosis. The objective of this study was to compare overall survival (OS) data in patients treated with trastuzumab + pertuzumab followed by trastuzumab-emtansine (T-DM1) in the second line of metastatic treatment (Arm A) versus patients treated with trastuzumab alone (Arm B). Progression-free survival (PFS) in first-line metastatic patients was also compared in both arms. Methods: This single-center retrospective study included patients from February 2008 to August 2022. OS and PFS of both arms were described and estimated using the Kaplan-Meier method. Data were extracted from electronic medical records and CHIMIO prescribing software. Results: The total duration of metastatic treatment of the 82 patients was significantly longer in the arm A (43.2 ± 28 months vs 33.6 ± 28.9 months), as was the median time to death (59 vs 52 months). The OS data showed a significant reduction in the risk of death in the arm A (Hazard Ratio = 0.59; 95% Confidence Interval [0.37-0.94]; p = 0.02). No difference was shown for PFS. Conclusion: The trastuzumab/pertuzumab/T-DM1 combination showed a significant improvement in OS. Our results are in line with the CLEOPATRA and EMILIA studies, but long-term responders in the arm A may have impacted our results. The absence of difference in term of PFS in first metastatic line may be explained by a selection bias, as patients in the arm A potentially have more aggressive forms.

Examining cardiac toxicity in HER2-positive breast cancer patients using trastuzumab and its influencing factors at Iran Hospital.

Trastuzumab is primarily utilized in the treatment of patients with human epidermal growth factor receptor 2 (HER2) positive breast cancer. This study aimed to investigate the incidence of cardiac toxicity associated with trastuzumab in HER2-positive breast cancer patients at Iran Hospital in 2023, as well as the factors influencing this toxicity. In this cross-sectional study, 200 patients diagnosed with HER2-positive breast cancer and receiving trastuzumab were included. The criteria for heart failure in this study were defined as an ejection fraction (EF) of less than 50% or a decrease of greater than 10% in EF. Descriptive statistics, the chi-square statistical test, Fisher's exact test, and logistic regression analyses were employed to assess the variables. A p-value of less than 0.05 was deemed statistically significant. The mean age of the participants was 51.5 ± 2.5 years. The odds ratio (OR) for the variable of anthracyclines was 1.3 (95% CI: 1.2-1.4); for opium use, the OR was 2.7 (95% CI: 0.9-8.5); for diabetes, the OR was 2.7 (95% CI: 1.2-5.9); for ischemic heart disease, the OR was 3.5 (95% CI: 1.6-7.7); and for hypertension, the OR was 4.8 (95% CI: 2.1-10.7). The OR for obesity was 1.45 (95% CI: 1.01-2.18), and the OR for age was 1.10 (95% CI: 1.01-1.12). No statistically significant association was found between opium use and cardiotoxicity (p = 0.07). This research contributes to the identification of factors that may predict responses to anthracyclines and the potential for cardiotoxicities. Ultimately, this information could inform the development of more personalized treatment strategies.

Effects of immunorelated gene polymorphisms on trastuzumab targeting breast cancer cell in vitro.

Aim: To investigate the associations between genetic polymorphisms in immunorelated genes and PBMC-induced cytotoxicity to breast cancer cell with the treatment of trastuzumab in vitro.Methods: Trastuzumab-mediated cytotoxicity of peripheral blood mononuclear cells (PBMC) from 148 healthy donors and 13 BC patients was analyzed by flow cytometry. 16 SNPs in 7 immunorelated genes were genotyped by Sequenom Mass Array Genotype Platform.Results: Cytotoxicity in the trastuzumab treated PBMCs were significantly higher than those of the basal group. A wide variability in trastuzumab-mediated cytotoxicity was observed, and PBMC from individuals with the CD247 rs16859030 T genotype generated increased cytotoxicity than those with the CC genotype.Conclusion: The CD247 rs16859030 polymorphism affects trastuzumab-mediated cytotoxicity in vitro.

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LC-HRMS-based global metabolomics profiling unravels the distinct metabolic signature of lapatinib-resistant and trastuzumab-resistant HER2+ breast cancer cells.

The effectiveness of lapatinib (LAP) and trastuzumab (TRZ), the first-line therapies for HER2+ breast cancer, has been limited owing to the development of acquired resistance in patients with HER2+. This study aimed to investigate the alterations in metabolic signatures in LAP-resistant HCC1954 and TRZ-resistant HCC1954 and pathways in human HER2+ breast cancer cells using liquid chromatography-high-resolution mass spectrometry (LC-HRMS) and enrichment analysis. The HCC1954 parental cells were sequentially treated 13 rounds with LAP or TRZ to develop resistant cells and then tested for their cytotoxicity using the MTT assay. Metabolites were prepared from HCC1954 parental (MBXWT), HCC1954-LAP (MBXLAP), and HCC1954-TRZ (MBXTRZ) cells prior to LC-HRMS, chemometric, enrichment, and joint pathway analyses. LAP- and TRZ-resistant cells were successfully developed from HCC1954, and 29 and 17 differentially expressed metabolites (DEMs) were identified between MBXWT-MBXLAP and MBXWT-MBXTRZ, respectively. The analysis of DEMs between MBXWT and MBXLAP revealed significant enrichment in D-amino acid metabolism, while MBXWT and MBXTRZ identified valine, leucine, isoleucine biosynthesis, ascorbate, and aldarate metabolism. Joint pathway enrichment analysis of LAP-resistant DEMs and differentially expressed genes (DEGs) showed enrichment in glutathione metabolism, while that of TRZ-resistance and DEGs showed enrichment in carbohydrate metabolism, namely pentose and glucuronate interconversions, starch and sucrose metabolism, and galactose metabolism. The findings from this study indicate considerable metabolic changes in LAP- and TRZ-resistant HCC1954 cells, which are crucial for understanding the resistance mechanisms and developing strategies to overcome these problems.

Evaluation of Potency and Specificity of Cryptophycin-Loaded Antibody-Drug Conjugates.

An enhanced variant of the antimitotic toxin cryptophycin was conjugated to the anti-Her2 monoclonal antibody (mAb) Trastuzumab upon Michael addition. Either antibodies with freed hinge-region cysteines or THIOMAB formats with engineered cysteines in the mAbs light chain were added to a maleimide derivative of cryptophycin. These Antibody-Drug Conjugates (ADCs) showed retained binding to Her2 positive tumor cells and highly efficient cell killing in double-digit pM range on high Her2-expressing SK-BR-3 cells. Two ADCs (DAR 6, DAR 3) showed superior cell killing of the cell lines JIMT-1 and RT112 with medium receptor expression level in comparison with a DAR 6 MMAE ADC serving as reference. The observed cell cytotoxicity is target-dependent since no impact on cell viability was observed for low Her2-expressing MDA-MB468 cells. Particularly the DAR 3 ADC in THIOMAB format exhibiting desirable biophysical properties and high potency emerged as a promising candidate for further in vivo investigations.

De-Escalating Treatment Strategies for Patients with Human Epidermal Growth Factor Receptor-2 (HER2)-Positive Early-Stage Breast Cancer.

Almost one-fifth of breast cancer cases express Human Epidermal Growth Factor-2 (HER2), and such expression is associated with highly proliferative tumors and poor prognosis. The introduction of anti-HER2 therapies has dramatically changed the natural course of this aggressive subtype of breast cancer. However, anti-HER2 therapy can be associated with substantial toxicities, mostly cardiac, and high cost. Over the past few years, there has been growing interest in de-escalation of anti-HER2 therapies to minimize adverse events and healthcare costs, while maintaining the efficacy of treatment. Data from clinical observations and single-arm studies have eluted to the minimal impact of anti-HER2 therapy in low-risk patients, like those with node-negative and small tumors. Though single-arm, the APT trial, in which patients with node-negative, small tumors received single-agent paclitaxel for 12 cycles plus trastuzumab for 1 year, was a practice-changing study. Several other recently published studies, like the PERSEPHONE trial, have shown more convincing data that 6 months of trastuzumab is not inferior to 12 months, in terms of disease-free survival (DFS), suggesting that de-escalating strategies with shorter treatment may be appropriate for some low-risk patients. Other de-escalating strategies involved an adaptive, response-directed approach, and personalized therapy that depends on tumor genomic profiling.

Real-world effectiveness and safety of trastuzumab-deruxtecan in Japanese patients with HER2-positive advanced gastric cancer (EN-DEAVOR study).

BACKGROUND: Trastuzumab-deruxtecan (T-DXd) was approved for the treatment of HER2-positive patients with advanced gastric cancer in Japan based on the results of the DESTINY-Gastric01 trial. This study aimed to collect real-world data and evaluate the effectiveness and safety of T-DXd. METHODS: Patients aged ≥ 20 years at the start of T-DXd administration with a histopathologically confirmed diagnosis of HER2-positive unresectable advanced or recurrent gastric or gastroesophageal junction (GEJ) adenocarcinoma that had worsened after chemotherapy were enrolled in this retrospective cohort study. Key outcomes included T-DXd treatment status, overall survival (OS), real-world progression-free survival (rwPFS), time to treatment failure (TTF), objective response rate and frequency of grade ≥ 3 adverse events (AEs). RESULTS: Of the 312 patients included in the analysis, 75.3% were male, the median (range) age was 70.0 (27.0-89.0) years, 12.2% had an ECOG PS ≥ 2, 43.3% had ascites and the initial T-DXd dose was > 5.4- ≤ 6.4 mg/kg in 78.2% of patients. The median (95% confidence interval) OS, rwPFS and TTF (months) was 8.9 (8.0-11.0), 4.6 (4.0-5.1) and 3.9 (3.4-4.2), respectively. The response rate was 42.9% in patients with a target lesion. In total, 48.4% of patients experienced a grade ≥ 3 AE, 2.6% experienced grade 5 AEs and 60.9% experienced AEs leading to T-DXd dose adjustments (reduction: 36.9%, interruption: 34.0% or discontinuation: 23.7%). No new safety signals were detected. CONCLUSIONS: T-DXd was effective and had a manageable safety profile as a third- or later-line treatment for patients with HER2-positive gastric or GEJ cancer in Japanese clinical practice. CLINICAL TRIAL REGISTRATION: UMIN000049032.

Immunomodulatory effects of trastuzumab deruxtecan through the cGAS-STING pathway in gastric cancer cells.

Although the efficacy of trastuzumab deruxtecan (T-DXd) against HER2-positive gastric cancers (GCs) has driven its clinical application, the precise mechanisms governing its immunomodulatory role remain unclear. In this study, we examined the immune-related mechanisms of action of T-DXd in GC cells. T-DXd exhibited potent antitumor effects in GC cells across diverse HER2 expression levels by inducing DNA damage and apoptosis. Activation of the DNA damage response by T-DXd led to increased PD-L1 expression. RNA-Seq analysis revealed that T-DXd modulated immune-related pathways, resulting in the upregulation of genes associated with inflammation and IFN signaling. Importantly, T-DXd activated the cGAS-STING pathway, inducing an IFN-I response in HER2-positive GC cells. Furthermore, T-DXd activated dendritic cells via the cancer cell-intrinsic cGAS-STING-IFN axis and enhanced PBMC-mediated tumor cell killing by activating CD8+ T cells. These findings provide valuable insights into the role of the cytosolic DNA sensing pathway in the action of T-DXd and offer a compelling rationale for combining T-DXd with immune checkpoint blockade therapies in GC treatment.

Final analysis of the ALTTO trial: adjuvant trastuzumab in sequence or in combination with lapatinib in patients with HER2-positive early breast cancer [BIG 2-06/NCCTG N063D (Alliance)].

BACKGROUND: Dual anti-human epidermal growth factor receptor 2 (HER2) blockade has improved the outcomes of patients with early and metastatic HER2-positive breast cancer. Here we present the final 10-year analysis of the ALTTO trial. PATIENTS AND METHODS: The ALTTO trial (NCT00490139) is a prospective randomized, phase III, open-label, multicenter study that investigated the role of adjuvant chemotherapy and trastuzumab alone, in combination or sequentially with lapatinib. The primary endpoint was disease-free survival (DFS) and secondary endpoints included overall survival (OS), time to distant recurrence and safety. RESULTS: Overall, 6281 patients with HER2-positive early breast cancer were included in the final efficacy analysis in three treatment groups: trastuzumab (T), lapatinib + trastuzumab (L + T) and trastuzumab followed by lapatinib (T→L). Baseline characteristics were well balanced between groups. At a median follow-up of 9.8 years, the addition of lapatinib to trastuzumab and chemotherapy did not significantly improve DFS nor OS. The 10-year DFS was 77% in T, 79% in L + T and 79% in T→L, and the 10-year OS was 87%, 89% and 89%, respectively. The incidence of any cardiac event was low and similar in the three treatment groups. CONCLUSIONS: With a longer follow-up, no significant improvement was observed in DFS in patients treated with dual anti-HER2 blockade with lapatinib + trastuzumab compared to trastuzumab alone. The 10-year survival rates for the combination group are consistent with other studies that have explored dual anti-HER2 therapy.

FCGR3A V158F gene polymorphism and trastuzumab response in HER2-positive breast cancer patients.

Breast cancer is considered a multifactorial disease, with genetic factors playing an important role in diagnosis and treatment. FCGR3A encodes the receptor for the Fc portion of immunoglobulin G that has been linked to the trastuzumab response. Our study aimed to investigate the association of FCGR3A-V158F gene polymorphism with breast cancer and to evaluate the impact of FCGR3A-V158F gene polymorphism on trastuzumab response in HER2-positive breast cancer patients. The study was conducted on eighty breast cancer patients who were collected from the Department of Oncology at Ain Shams University Hospitals; in addition, twenty age-matched healthy subjects were taken as a healthy control group. Patients were further sub-classified according to their responses. The study showed that there were no statistically significant differences between patients and controls regarding FCGR3A-V158F gene polymorphism genotypes. However, there was a significant association between the concordance of this polymorphism and the response to trastuzumab therapy among the patient's group. V/V is associated with better treatment response and overall survival (OS) compared to F/V and F/F alleles. Assessment of FCGR3A-V158F gene polymorphism might be useful in making a treatment decision in HER2-positive breast cancer patients.

Efficacy and safety of dual blockade of HER2 and PD-1 in patients with HER2-positive gastric cancer: a retrospective, multicentre study.

Human epidermal growth factor receptor 2 (HER2) expression is one of the most important pathological characteristics of gastric cancer. The positive rate of HER2 expression in patients with gastric cancer is approximately 20%. The phase III Keynote-811 study revealed that anti-HER2 and anti-PD-1 therapy combined with chemotherapy could significantly improve the objective response rate as first-line treatment in patients with HER2-positive advanced gastric cancer. In the present study, we aimed to evaluate the efficacy of combination therapy with trastuzumab and PD-1 inhibitors in patients with advanced HER2-positive gastric cancer in a real-world setting. Seventy-two HER2-positive gastric cancer patients from three hospitals in China were retrospectively reviewed. These patients were treated with trastuzumab plus one anti-PD-1 agent with or without chemotherapy. The overall response rate, progression-free survival and overall survival were assessed according to the Response Evaluation Criteria in Solid Tumours (RECIST 1.1). From January 2018 to October 2021, 72 patients with HER2-positive gastric cancer received trastuzumab and a PD-1 inhibitor with or without chemotherapy as neoadjuvant chemotherapy, first-line therapy, second-line therapy or salvage therapy. The ORR was 54.2% for all patients and 79.4% for previously untreated patients. The median PFS and median OS were 10 months (95% CI: 8-13 months) and 26.1 months (95% CI: 18.5-NA months), respectively, for all patients. Grade 3 adverse effects occurred in approximately 25% of patients. Immune-related adverse effects occurred in approximately 12.5% of patients. Trastuzumab and PD-1 inhibitor combination therapy with or without chemotherapy achieved satisfactory survival outcomes in patients with HER2-positive gastric cancer with acceptable safety.

Anti-HER2 biparatopic antibody KJ015 has near-native structure, functional balanced high affinity, and synergistic efficacy with anti-PD-1 treatment in vivo.

Currently approved human epidermal growth factor receptor 2 (HER2)-targeted antibody therapies are largely derived from trastuzumab, including trastuzumab-chemotherapy combinations, fixed-dose trastuzumab-pertuzumab combinations, and trastuzumab antibody-drug conjugates. To expand the options, bispecific antibodies, which may better utilize the benefits of combination therapy, are being developed. Among them, biparatopic antibodies (bpAbs) have shown improved efficacy compared to monoclonal antibody (mAb) combinations in HER2-positive patients. BpAbs bind two independent epitopes on the same antigen, which allows fine-tuning of mechanisms of action, including enhancement of on-target specificity and induction of strong antigen clustering due to the unique binding mode. To fully utilize the potential of bpAbs for anti-HER2 drug development, it is crucial to consider formats that offer stability and high-yield production, along with a functional balance between the two epitopes. In this study, we rationally designed a bpAb, KJ015, that shares a common light chain with two Fab arms and exhibits functionally balanced high affinity for two HER2 non-overlapping epitopes. KJ015 demonstrated high-expression titers over 7 g/L and stable physicochemical properties at elevated concentrations, facilitating subcutaneous administration with hyaluronidase. Moreover, KJ015 maintained comparable antibody-dependent cytotoxicity, phagocytosis, and complement-dependent cytotoxicity with trastuzumab plus pertuzumab. It exhibited enhanced synergy when administered subcutaneously with hyaluronidase and anti-PD-1 mAb in a mouse tumor model, suggesting promising clinical prospects for this combination.