A Multispecific Anti-CD40 DARPin Construct Induces Tumor-Selective CD40 Activation and Tumor Regression.

The CD40 receptor is an attractive target for cancer immunotherapy. Although a modest pharmacodynamic effect is seen in patients following administration of CD40-targeting monoclonal antibodies (mAb), the doses that could be safely administered do not result in a meaningful clinical response, most likely due to the limited therapeutic window associated with systemic CD40 activation. To overcome this issue, we developed a multispecific DARPin construct, α-FAPxCD40, which has conditional activity at the site of disease.

Antibody drug conjugates for treatment of breast cancer: Novel targets and diverse approaches in ADC design.

Breast cancer is a heterogeneous group of malignancies with a spectrum of molecular subtypes, pathologies and outcomes that together comprise the most common non-cutaneous cancer in women. Currently, over 80% of breast cancer patients are diagnosed at relatively early stages of disease where there are encouraging data on outcomes and long term survival. However, there is currently no curative option for those patients with metastatic disease and there is a substantial medical need to identify effective and safe treatment options for these patients.

Preclinical Activity of the Novel Anti-Prolactin Receptor (PRLR) Antibody-Drug Conjugate REGN2878-DM1 in PRLR-Positive Breast Cancers.

The Prolactin Receptor (PRLR) is a type 1 cytokine receptor that is expressed in a subset of breast cancers and may contribute to its pathogenesis. It is relatively overexpressed in approximately 25% of human breast tumors while expressed at low levels in some normal human tissues including the mammary gland. We developed an anti-PRLR antibody-drug conjugate (ADC), to target PRLR-positive breast cancer.

A Phase I First-in-Human Study of Nesvacumab (REGN910), a Fully Human Anti-Angiopoietin-2 (Ang2) Monoclonal Antibody, in Patients with Advanced Solid Tumors.

Purpose: Nesvacumab (REGN910) is a fully human immunoglobulin G1 (IgG1) monoclonal antibody that specifically binds and inactivates the Tie2 receptor ligand Ang2 with high affinity, but shows no binding to Ang1. The main objectives of this trial were to determine the safety, tolerability, dose-limiting toxicities (DLT), and recommended phase II dose (RP2D) of nesvacumab.

Experimental Design: Nesvacumab was administered intravenously every two weeks with dose escalations from 1 to 20 mg/kg in patients with advanced solid tumors.

Dual IGF-I/II-neutralizing antibody MEDI-573 potently inhibits IGF signaling and tumor growth.

Insulin-like growth factors (IGF), IGF-I and IGF-II, are small polypeptides involved in regulating cell proliferation, survival, differentiation, and transformation. IGF activities are mediated through binding and activation of IGF-1R or insulin receptor isoform A (IR-A). The role of the IGF-1R pathway in promoting tumor growth and survival is well documented.

Sorafenib (BAY 43-9006) inhibits tumor growth and vascularization and induces tumor apoptosis and hypoxia in RCC xenograft models.

Purpose: New research findings have revealed a key role for vascular endothelial growth factor (VEGF) in the stimulation of angiogenesis in clear cell renal carcinoma (RCC) which is a highly vascularized and treatment-resistant tumor. Sorafenib (BAY 43-9006, Nexavar) is a multi-kinase inhibitor which targets receptor tyrosine and serine/threonine kinases involved in tumor progression and tumor angiogenesis. The effect of sorafenib on tumor growth and tumor histology was assessed in both ectopic and orthotopic mouse models of RCC.

Sorafenib (BAY 43-9006, Nexavar), a dual-action inhibitor that targets RAF/MEK/ERK pathway in tumor cells and tyrosine kinases VEGFR/PDGFR in tumor vasculature.

Activating mutations in Ras and B-RAF were identified in several human cancers. In addition, several receptor tyrosine kinases, acting upstream of Ras, were found either mutated or overexpressed in human tumors. Because oncogenic activation of the Ras/RAF pathway may lead to a sustained proliferative signal resulting in tumor growth and progression, inhibition of this pathway represents an attractive approach for cancer drug discovery.

BAY 43-9006 exhibits broad spectrum oral antitumor activity and targets the RAF/MEK/ERK pathway and receptor tyrosine kinases involved in tumor progression and angiogenesis.

The RAS/RAF signaling pathway is an important mediator of tumor cell proliferation and angiogenesis. The novel bi-aryl urea BAY 43-9006 is a potent inhibitor of Raf-1, a member of the RAF/MEK/ERK signaling pathway. Additional characterization showed that BAY 43-9006 suppresses both wild-type and V599E mutant BRAF activity in vitro.

BR96 conjugates of highly potent anthracyclines.

The 6-maleimidocaproylhydrazone derivatives of highly potent antitumor agents 5-Diacetoxypentyldoxorubicin and Morpholinodoxorubicin were synthesized and conjugated to monoclonal antibody BR96 and control IgG. Immunoconjugate molar ratios were generally 7.5-8.

Monoclonal antibody drug immunoconjugates for targeted treatment of cancer.

Monoclonal antibodies (mAb) directed to tumor-associated antigens (TAA) or antigens differentially expressed on the tumor vasculature have been covalently linked to drugs that have different mechanisms of action and various levels of potency. The use of these mAb immunoconjugates to selectively deliver drugs to tumors has the potential to both improve antitumor efficacy and reduce the systemic toxicity of therapy. Several immunoconjugates, particularly those that incorporate internalizing antibodies and tumor-selective linkers, have demonstrated impressive activity in preclinical models.

Monoclonal antibody conjugates of doxorubicin prepared with branched peptide linkers: inhibition of aggregation by methoxytriethyleneglycol chains.

High mole ratio BR96 immunoconjugates were synthesized using branched peptide-doxorubicin linkers designed to liberate doxorubicin following antigen-specific internalization into lysosomes. However, these immunoconjugates are highly prone to noncovalent, dimeric aggregation. We hypothesize that this is due to (1) the hydrophobic nature of the peptides, (2) the loss of positive charge upon amide formation at the 3'-amino group of doxorubicin, and (3) the proximity of the peptide hydrophobic residues to form efficient intermolecular stacking interactions.

Cathepsin B-labile dipeptide linkers for lysosomal release of doxorubicin from internalizing immunoconjugates: model studies of enzymatic drug release and antigen-specific in vitro anticancer activity.

The anticancer drug doxorubicin (DOX) has been linked to chimeric BR96, an internalizing monoclonal antibody that binds to a Lewis(y)-related, tumor-associated antigen, through two lysosomally cleavable dipeptides, Phe-Lys and Val-Cit, giving immunoconjugates 72 and 73. A self-immolative p-aminobenzyloxycarbonyl (PABC) spacer between the dipeptides and the DOX was required for rapid and quantitative generation of free drug. DOX release from model substrate Z-Phe-Lys-PABC-DOX 49 was 30-fold faster than from Z-Val-Cit-PABC-DOX 42 with the cysteine protease cathepsin B alone, but rates were identical in a rat liver lysosomal preparation suggesting the participation of more than one enzyme.

Doxorubicin immunoconjugates containing bivalent, lysosomally-cleavable dipeptide linkages.

Bivalent doxorubicin (DOX)-dipeptides (16a-c) were prepared and conjugated to the monoclonal antibody BR96. The dipeptides are cleaved by lysosomal proteases following internalization of the resulting immunoconjugates. Conjugate 18b demonstrated antigen-specific in vitro tumor cell killing activity (IC(50)=0.

Synthesis of an immunoconjugate of camptothecin.

The first immunoconjugate of camptothecin has been synthesized wherein the drug is attached to the tumor-recognizing antibody BR96 via a Cathepsin B cleavable linker. Endocytosis of the immunoconjugate upon binding to the tumor cell followed by enzymatic cleavage of the linker inside the endosome ensures tumor-specific release of the drug. In this way, it is hoped that the dose-limiting side effects associated with camptothecin can be eliminated while the antitumor activity is preserved.