Tumor-derived biomarkers predict efficacy of B7H3 antibody-drug conjugate treatment in metastatic prostate cancer models

Antibody-drug conjugates in breast cancer treatment: resistance mechanisms and the role of therapeutic sequencing

Antibody-drug conjugates (ADCs) are a transformative approach in breast cancer therapy, offering targeted treatment with reduced toxicity by selectively delivering cytotoxic agents to cancer cells. While ADCs like trastuzumab emtansine (T-DM1), trastuzumab deruxtecan (T-DXd), and sacituzumab govitecan have shown significant efficacy, resistance mechanisms such as antigen loss, impaired internalization, and efflux of cytotoxic payloads challenge their effectiveness. This review discusses these resistance mechanisms and explores advanced strategies to overcome them, including innovations in linker chemistry, multi-antigen targeting, and biomarker-driven personalization. Additionally, therapeutic sequencing - determining the optimal order of ADCs with other treatments such as chemotherapy, endocrine therapy, and immunotherapy - is examined as a crucial approach to maximize ADC efficacy and manage resistance. Evidence-based sequencing strategies, particularly for human epidermal growth factor receptor 2 (HER2)-positive and triple-negative breast cancer (TNBC), are supported by clinical trials demonstrating the benefits of ADCs in both early-stage and metastatic settings. The potential of combination therapies, such as ADCs with immune checkpoint inhibitors (ICIs), further highlights the evolving landscape of breast cancer treatment. As ADC technology advances, personalized approaches integrating biomarkers and optimized sequencing protocols offer promising avenues to enhance treatment outcomes and combat resistance in breast cancer.

A whole-body imaging technique for tumor-specific diagnostics and screening of B7H3-targeted therapies

BACKGROUNDB7H3, also known as CD276, is notably overexpressed in various malignant tumor cells in humans, with extremely high expression rates. The development of a radiotracer that targets B7H3 may provide a universal tumor-specific imaging agent and allow the noninvasive assessment of the whole-body distribution of B7H3-expressing lesions.METHODSWe enhanced and optimized the structure of an affibody (ABY) that targets B7H3 to create the radiolabeled radiotracer [68Ga]Ga-B7H3-BCH, and then, we conducted both foundational experiments and clinical translational studies.RESULTS[68Ga]Ga-B7H3-BCH exhibited high affinity (equilibrium dissociation constant [KD] = 4.5 nM), and it was taken up in large amounts by B7H3-transfected cells (A549CD276 and H1975CD276 cells); these phenomena were inhibited by unlabeled precursors. Moreover, PET imaging of multiple xenograft models revealed extensive [68Ga]Ga-B7H3-BCH uptake by tumors. In a clinical study including 20 patients with malignant tumors, the [68Ga]Ga-B7H3-BCH signal aggregated in both primary and metastatic lesions, surpassing fluorine-18 fluorodeoxyglucose (18F-FDG) in overall diagnostic efficacy for tumors (85.0% vs. 81.7%), including differentiated hepatocellular and metastatic gastric cancers. A strong correlation between B7H3 expression and [68Ga]Ga-B7H3-BCH uptake in tumors was observed, and B7H3 expression was detected with 84.38% sensitivity and 100% specificity when a maximum standardized uptake value (SUVmax) of 3.85 was set as the cutoff value. Additionally, B7H3-specific PET imaging is expected to predict B7H3 expression levels in tumor cells, intratumoral stroma, and peritumoral tissues.CONCLUSIONIn summary, [68Ga]Ga-B7H3-BCH has potential for the noninvasive identification of B7H3 expression in systemic lesions in patients with malignant tumors. This agent has prospects for improving pretreatment evaluation, predicting therapeutic responses, and monitoring resistance to therapy in patients with malignancies.TRIAL REGISTRATIONClinicalTrials.gov NCT06454955.FUNDINGThis research was financially supported by the Natural Science Foundation of Beijing Municipality (no. 7242266), the National Natural Science Foundation of China (no. 82202201), and the Young Elite Scientists Sponsorship Program by China Association for Science and Technology (CAST) (no. YESS20220230).

Improving Targeted Delivery and Antitumor Efficacy of TRAIL through Fusion with a B7H3-Antagonistic Affibody

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is an attractive candidate for anticancer therapeutics due to its efficient pro-apoptotic activity against tumor cells and its well-tolerated safety profile. However, the in vivo antitumor efficacy of TRAIL is often limited by its poor tumor targeting capacity. Nowadays, the B7 homologue 3 (B7-H3) immune checkpoint has emerged as a promising target for tumor immunotherapy and drug delivery. Here, we report the achievement of tumor-targeted delivery of TRAIL by genetically fusing it with a B7H3-antagonistic affibody. The affibody-TRAIL fusion protein, named ACT, was easily expressed in Escherichia coli with a high yield and could form the active trimeric state. In vitro ACT showed significantly increased cellular binding to multiple B7H3-positive tumor cells and improved cytotoxicity by 2-3 times compared to the parent TRAIL. In vivo ACT demonstrated a 2.4-fold higher tumor uptake than TRAIL in mice bearing B7H3-positive A431 tumor grafts. More importantly, ACT exhibited significantly improved antitumor efficacy against tumors in vivo. In addition, ACT treatment did not cause body weight loss or histopathological changes in the major organs of mice, indicating its good safety profile. Overall, our findings demonstrate that targeting B7H3 to enhance TRAIL delivery is a viable approach to improve its therapeutic efficacy, and ACT may be a potential agent for targeted therapy of B7H3-positive tumors.

Immune checkpoint B7-H3 is a potential therapeutic target in prostate cancer

High expression of immune checkpoint molecule B7-H3 (CD276) in many cancer types makes it a promising immunotherapeutic target. Both coinhibitory and costimulatory effects of B7-H3 in tumors have been demonstrated, but the mechanism of B7-H3 immune response under dual effects is open to question. B7-H3 is crucially involved in the migration and invasion, angiogenesis, metabolism and chemotherapy resistance of prostate cancer. In addition to the potential immune effects on tumor environment, B7-H3 plays a non-immune-mediated role in tumor progression. In this review, we summarize current understanding of molecular mechanism of B7-H3 in prostate cancer and discuss the potential of B7-H3 as a novel therapeutic target for prostate cancer.

Castrate-resistant prostate cancer response to taxane is determined by an HNF1-dependent apoptosis resistance circuit

Metastatic castrate-resistant prostate cancer (mCRPC) is a genetically and phenotypically heterogeneous cancer where advancements are needed in biomarker discovery and targeted therapy. A critical and often effective component of treatment includes taxanes. We perform a high-throughput screen across a cohort of 30 diverse patient-derived castrate-resistant prostate cancer (CRPC) organoids to a library of 78 drugs. Combining quantitative response measures with transcriptomic analyses demonstrates that HNF1 homeobox A (HNF1A) drives a transcriptional program of taxane resistance, commonly dependent upon cellular inhibitor of apoptosis protein 2 (cIAP2). Monotherapy with cIAP2 inhibitor LCL161 is sufficient to treat HNF1A+ models of mCRPC previously resistant to docetaxel. These data may be useful in future clinical trial designs.

Recent Technological and Intellectual Property Trends in Antibody-Drug Conjugate Research

Antibody-drug conjugate (ADC) therapy, an advanced therapeutic technology comprising antibodies, chemical linkers, and cytotoxic payloads, addresses the limitations of traditional chemotherapy. This study explores key elements of ADC therapy, focusing on antibody development, linker design, and cytotoxic payload delivery. The global rise in cancer incidence has driven increased investment in anticancer agents, resulting in significant growth in the ADC therapy market. Over the past two decades, notable progress has been made, with approvals for 14 ADC treatments targeting various cancers by 2022. Diverse ADC therapies for hematologic malignancies and solid tumors have emerged, with numerous candidates currently undergoing clinical trials. Recent years have seen a noteworthy increase in ADC therapy clinical trials, marked by the initiation of numerous new therapies in 2022. Research and development, coupled with patent applications, have intensified, notably from major companies like Pfizer Inc. (New York, NY, USA), AbbVie Pharmaceuticals Inc. (USA), Regeneron Pharmaceuticals Inc. (Tarrytown, NY, USA), and Seagen Inc. (Bothell, WA, USA). While ADC therapy holds great promise in anticancer treatment, challenges persist, including premature payload release and immune-related side effects. Ongoing research and innovation are crucial for advancing ADC therapy. Future developments may include novel conjugation methods, stable linker designs, efficient payload delivery technologies, and integration with nanotechnology, driving the evolution of ADC therapy in anticancer treatment.