In Vivo Activation of Duocarmycin–Antibody Conjugates by Near-Infrared Light

Abstract

Near-IR photocaging groups based on the heptamethine cyanine scaffold present the opportunity to visualize and then treat diseased tissue with potent bioactive molecules. Here we describe fundamental chemical studies that enable biological validation of this approach. Guided by rational design, including computational analysis, we characterize the impact of structural alterations on the cyanine uncaging reaction. A modest change to the ethylenediamine linker (N,N′-dimethyl to N,N′-diethyl) leads to a bathochromic shift in the absorbance maxima, while decreasing background hydrolysis. Building on these structure–function relationship studies, we prepare antibody conjugates that uncage a derivative of duocarmycin, a potent cytotoxic natural product. The optimal conjugate, CyEt-Pan-Duo, undergoes small molecule release with 780 nm light, exhibits activity in the picomolar range, and demonstrates excellent light-to-dark selectivity. Mouse xenograft studies illustrate that the construct can be imaged in vivo prior to uncaging with an external laser source. Significant reduction in tumor burden is observed following a single dose of conjugate and near-IR light. These studies define key chemical principles that enable the identification of cyanine-based photocages with enhanced properties for in vivo drug delivery.

A chemically stable fluorescent marker of the ureter

“…Our prior studies have suggested that installing a charged functional group proximate to the C4’-position of cyanine polyene serves to mitigate the formation of undesirable H-aggregates, a common issue with these molecules. 15, 22, 23 To introduce this charge, as well as to provide net-netural molecules, we installed a trimethylalkyl-ammonium ether at the C4’ position. To examine the role of the alkyl linker, we have prepared both propyl and ethyl variants.…”

Innovative Linker Strategies for Tumor‐Targeted Drug Conjugates

“…In the absence of irradiation with NIR light, the linker‐drug module showed high stability in solution ( t 10 % =230 h), while the photorelease mechanism occurred with a half‐life of 90 min. The linker–drug module conjugated to the anti‐EGFR mAb panitumumab ( 49 ) showed promising anticancer activity in mice xenografted with MDA‐MB‐468 cancer cells . ADC 49 was evaluated in combined therapy with a second mAb conjugated to a photoabsorber (i.e.…”

“… A) Examples of π‐extended photosensitive linkers, cleavable by either two‐photon (TP, as compound 47 ) or single‐photon (SP, compound 48 ) excitation with NIR wavelengths. B) ADC 49 developed by Schnermann and co‐workers, based on a NIR light‐sensitive cyanine linker, a duocarmycin (Duo) payload and a diamine‐based self‐immolative spacer (depicted in green) …”

DNA damaging agent-based antibody-drug conjugates for cancer therapy

“…Chemical [70], near-infrared light [71] and tumor microenvironment-triggered payload release strategies have also shown promising results. There is probably no universal conjugate-linkage strategy optimal for all antibody-drug conjugates.…”