A phase I study of pharmacokinetics of trastuzumab emtansine in Chinese patients with locally advanced inoperable or metastatic human epidermal growth factor receptor 2-positive breast cancer who have received prior trastuzumab-based therapy

Gastrointestinal Toxicity of Antibody Drug Conjugates (ADCs) in Metastatic Breast Cancer: A Pooled Analysis

Trastuzumab emtansine (T-DM1), sacituzumab govitecan (SG), and trastuzumab deruxtecan (T-DXd) are three ADCs approved for the treatment of metastatic breast cancer (MBC). Since gastrointestinal toxicities have been commonly observed with these drugs in clinical trials, a pooled analysis evaluating gastrointestinal adverse events (AEs) in patients with MBC treated with ADCs in clinical trials was performed. PubMed, Embase, and the Cochrane Library were searched from inception until May 2023 for phase II and III clinical trials reporting frequency and severity of gastrointestinal AEs during treatment with ADCs. Data were retrieved for nausea, vomiting, diarrhea, constipation, and abdominal pain: overall and grade 3-4 toxicity rates according to NCI-CTCAE were collected and expressed as proportions. A pre-specified subgroup analysis according to the agent was also carried out. Fourteen studies, comprising 5608 patients, were included in the analysis. Gastrointestinal AEs were frequently registered with SG and T-DXd. A significantly higher frequency of nausea (65.6% with SG, 75% with T-DXd), vomiting (43.7% with SG, 45% with T-DXd), and diarrhea (59.7% with SG, 29% with T-DXd) was noticed with these ADCs compared to TDM-1. Furthermore, diarrhea was more frequently associated with SG (grade 3 in 7.5% of patients), while constipation and abdominal pain were less common. Gastrointestinal AEs, notably nausea and diarrhea, were frequently reported by MBC patients treated with SG and T-DXd in clinical trials. Since these ADCs are administered continuously until disease progression or occurrence of unbearable AEs, gastrointestinal toxicity may have a negative impact on patient quality of life. Therefore, appropriate management of gastrointestinal AEs is mandatory to ensure treatment efficacy and adherence.

Anthracyclines induce cardiotoxicity through a shared gene expression response signature

TOP2 inhibitors (TOP2i) are effective drugs for breast cancer treatment. However, they can cause cardiotoxicity in some women. The most widely used TOP2i include anthracyclines (AC) Doxorubicin (DOX), Daunorubicin (DNR), Epirubicin (EPI), and the anthraquinone Mitoxantrone (MTX). It is unclear whether women would experience the same adverse effects from all drugs in this class, or if specific drugs would be preferable for certain individuals based on their cardiotoxicity risk profile. To investigate this, we studied the effects of treatment of DOX, DNR, EPI, MTX, and an unrelated monoclonal antibody Trastuzumab (TRZ) on iPSC-derived cardiomyocytes (iPSC-CMs) from six healthy females. All TOP2i induce cell death at concentrations observed in cancer patient serum, while TRZ does not. A sub-lethal dose of all TOP2i induces limited cellular stress but affects calcium handling, a function critical for cardiomyocyte contraction. TOP2i induce thousands of gene expression changes over time, giving rise to four distinct gene expression response signatures, denoted as TOP2i early-acute, early-sustained, and late response genes, and non-response genes. There is no drug- or AC-specific signature. TOP2i early response genes are enriched in chromatin regulators, which mediate AC sensitivity across breast cancer patients. However, there is increased transcriptional variability between individuals following AC treatments. To investigate potential genetic effects on response variability, we first identified a reported set of expression quantitative trait loci (eQTLs) uncovered following DOX treatment in iPSC-CMs. Indeed, DOX response eQTLs are enriched in genes that respond to all TOP2i. Next, we identified 38 genes in loci associated with AC toxicity by GWAS or TWAS. Two thirds of the genes that respond to at least one TOP2i, respond to all ACs with the same direction of effect. Our data demonstrate that TOP2i induce thousands of shared gene expression changes in cardiomyocytes, including genes near SNPs associated with inter-individual variation in response to DOX treatment and AC-induced cardiotoxicity.