Curative Properties of Noninternalizing Antibody–Drug Conjugates Based on Maytansinoids

Elena Perrino,Giulio Casi,Gonçalo J.L Bernardes,Francesca Pretto,Nikolaus Krall,Dario Neri,Martina Steiner

doi:10.1158/0008-5472.can-13-2990

Elena Perrino, Giulio Casi + Show 5 more

Open Access

https://doi.org/10.1158/0008-5472.can-13-2990

Copy DOI

Journal: Cancer Research	Publication Date: Apr 30, 2014
Citations: 121	License type: cc-by

Affiliation: University of Lisbon, ETH Zurich

Abstract

It is generally thought that the anticancer efficacy of antibody-drug conjugates (ADC) relies on their internalization by cancer cells. However, recent work on an ADC that targets fibronectin in the tumor microenvironment suggests this may not be necessary. The alternatively spliced extra domains A and B (EDA and EDB) of fibronectin offer appealing targets for ADC development, because the antigen is strongly expressed in many solid human tumors and nearly undetectable in normal tissues except for the female reproductive system. In this study, we describe the properties of a set of ADCs based on an antibody targeting the alternatively spliced EDA of fibronectin coupled to one of a set of potent cytotoxic drugs (DM1 or one of two duocarmycin derivatives). The DM1 conjugate SIP(F8)-SS-DM1 mediated potent antitumor activity in mice bearing DM1-sensitive F9 tumors but not DM1-insensitive CT26 tumors. Quantitative biodistribution studies and microscopic analyses confirmed a preferential accumulation of SIP(F8)-SS-DM1 in the subendothelial extracellular matrix of tumors, similar to the pattern observed for unmodified antibody. Notably, we found that treatments were well tolerated at efficacious doses that were fully curative and compatible with pharmaceutical development. Our findings offer a preclinical proof-of-concept for curative ADC targeting the tumor microenvironment that do not rely upon antigen internalization.

Highlights

Antibody–drug conjugates (ADC) represent an attractive class of biopharmaceuticals, which has gained considerable attention for the development of anticancer products [1, 2], especially after the approval of drugs such as Adcetris and Kadcyla [3, 4].It is generally believed that antibodies capable of selective internalization into the tumor cells are needed for efficient ADC development because cytotoxic drugs typically act at the level of intracellular targets
We show that small immunoprotein (SIP)(F8), but not the anti-hen egg lysozyme SIP(KSF) antibody used as negative control, is able to preferentially localize on solid tumors at doses of 7 mg/kg, both in the unmodified form and in the ADC form
ADC preparation and characterization Figure 1 illustrates the chemical strategies followed for the preparation of ADCs based on DM1 or duocarmycins and on the F8 and KSF antibodies in SIP format

Summary

Introduction

It is generally believed that antibodies capable of selective internalization into the tumor cells are needed for efficient ADC development because cytotoxic drugs typically act at the level of intracellular targets. It has been claimed that targeting an ADC to a noninternalizing target antigen with the expectation that extracellulary released drug will diffuse into the target cell is not a recipe for a successful ADC [5]. We have recently challenged the concept of a strict requirement for internalization in ADC development. We Authors' Affiliations: 1Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zu€rich; 2Philochem AG, Otelfingen, Zurich, Switzerland; 3Department of Chemistry, University of Cambridge, Cambridge, United Kingdom; and 4Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Prof.

Methods

Results

Conclusion