A homogeneous high-DAR antibody-drug conjugate platform combining THIOMAB antibodies and XTEN polypeptides.

The antibody-drug conjugate (ADC) is a well-validated modality for the cell-specific delivery of small molecules with impact expanding rapidly beyond their originally-intended purpose of treating cancer. However, antibody-mediated delivery (AMD) remains inefficient, limiting its applicability to targeting highly potent payloads to cells with high antigen expression. Maximizing the number of payloads delivered per antibody is one key way in which delivery efficiency can be improved, although this has been challenging to carry out; with few exceptions, increasing the drug-to-antibody ratio (DAR) above ∼4 typically destroys the biophysical properties and efficacy for ADCs.

A Novel Depurination Methodology to Assess DNA Alkylation of Chloro-Bis-Seco-Cyclopropylbenzoindoles Allowed for Comparison of Minor-Groove Reactivity.

Duocarmycins [including cyclopropyl pyrroloindole (CPI) or cyclopropyl benzoindole (CBI)] are a class of DNA minor-groove alkylators and seco-CPI/CBIs are synthetic pro-forms that can spirocyclize to CPI/CBI. Bis-CPI/CBIs are potential drug candidates because of their enhanced cytotoxicity from DNA crosslinking, but it is difficult to analyze them for structure-activity correlation because of their DNA reactivity. To study their DNA alkylation, neutral thermal hydrolysis has been frequently applied to process depurination.

Attachment Site Cysteine Thiol pK Is a Key Driver for Site-Dependent Stability of THIOMAB Antibody-Drug Conjugates.

The incorporation of cysteines into antibodies by mutagenesis allows for the direct conjugation of small molecules to specific sites on the antibody via disulfide bonds. The stability of the disulfide bond linkage between the small molecule and the antibody is highly dependent on the location of the engineered cysteine in either the heavy chain (HC) or the light chain (LC) of the antibody. Here, we explore the basis for this site-dependent stability.

Developments in therapy with monoclonal antibodies and related proteins.

Monoclonal antibody therapeutics have been approved for over 30 targets and diseases, most commonly cancer. Antibodies have become the new backbone of the pharmaceutical industry, which previously relied on small molecules. Compared with small molecules, monoclonal antibodies (mAbs) have exquisite target selectivity and hence less toxicity as a result of binding other targets.

The cryptophycins as potent payloads for antibody drug conjugates.

The cryptophycins are a potent class of cytotoxic agents that were evaluated as antibody drug conjugate (ADC) payloads. Free cryptophycin analog 1 displayed cell activity an order of magnitude more potent than approved ADC payloads MMAE and DM1. This potency increase was also reflected in the activity of the cryptophycin ADCs, attached via a either cleavable or non-cleavable linker.

Trastuzumab-DM1 (T-DM1) retains all the mechanisms of action of trastuzumab and efficiently inhibits growth of lapatinib insensitive breast cancer.

Trastuzumab (Herceptin(®)) is currently used as a treatment for patients whose breast tumors overexpress HER2/ErbB2. Trastuzumab-DM1 (T-DM1, trastuzumab emtansine) is designed to combine the clinical benefits of trastuzumab with a potent microtubule-disrupting drug, DM1 (a maytansine derivative). Currently T-DM1 is being tested in multiple clinical trials.

Angiogenesis-independent endothelial protection of liver: role of VEGFR-1.

The vascular endothelium was once thought to function primarily in nutrient and oxygen delivery, but recent evidence suggests that it may play a broader role in tissue homeostasis. To explore the role of sinusoidal endothelial cells (LSECs) in the adult liver, we studied the effects of vascular endothelial growth factor (VEGF) receptor activation on mouse hepatocyte growth. Delivery of VEGF-A increased liver mass in mice but did not stimulate growth of hepatocytes in vitro, unless LSECs were also present in the culture.

Inhibition of ligand-mediated HER2 activation in androgen-independent prostate cancer.

Hormone-independent tumor growth and metastasis are associated with increased mortality in human prostate cancer. In this study, we evaluate a potential role for ligand-mediated activation of HER2 receptor tyrosine kinase in androgen-independent prostate cancers. HER2, HER3, and epidermal growth factor receptor were detected in the androgen-independent cell line 22Rv1.