A series of boronic acid derived salicylidenehydrazone (BASHY) complexes was prepared and photophysically characterized. The dye platform can be modified by (a) electronic tuning along the cyanine-type axis via modification of the donor-acceptor pair and (b) functional tuning via the boronic acid residue. On the one hand, approach (a) allows the control of photophysical parameters such as Stokes shift, emission color, and two-photon-absorption (2PA) cross section. The resulting dyes show emission light-up behavior in nonpolar media and are characterized by high fluorescence quantum yields (ca. 0.5-0.7) and brightness (ca. 35000-40000 M cm). Moreover, the 2PA cross sections reach values in the order of 200-300 GM. On the other hand, the variation of the dye structure through the boronic acid derived moiety (approach (b)) enables the functionalization of the BASHY platform for a broad spectrum of potential applications, ranging from biorelevant contexts to optoelectronic materials. Importantly, this functionalization is generally electronically orthogonal with respect to the dye's photophysical properties, which are only determined by the electronic structure of the cyanine-type backbone (approach (a)). Rare exceptions to this generalization are the presence of redox-active residues (such a triphenylamine or pyrene). Finally, the advantageous photophysics is complemented by a significant photostability.

Antibody-drug conjugates (ADCs) are an ew class of therapeutics that combine the lethality of potent cytotoxic drugs with the targeting ability of antibodies to selectively deliver drugs to cancer cells.Inthis study we showfor the first time the synthesis of ar eactive-oxygen-species (ROS)-responsive ADC (VL-DAB31-SN-38) that is highly selective and cytotoxic to B-cell lymphoma (CLBL-1 cell line,IC 50 value of 54.1 nM). The synthesis of this ADC was possible due to the discovery that diazaborines (DABs) are avery effective ROSresponsive unit that are also very stable in buffer and in plasma. DFT calculations performed on this system revealed af avorable energetic profile (DGR = À74.3 kcal mol À1 )similar to the oxidation mechanism of aromatic boronic acids.D ABs very fast formation rate and modularity enabled the construction of different ROS-responsive linkers featuring self-immolative modules,b ioorthogonal functions,a nd bioconjugation handles.T hese structures were used in the site-selective functionalization of aV Lantibody domain and in the construction of the homogeneous ADC.

Antibody-drug conjugates (ADCs) are a new class of therapeutics that combine the lethality of potent cytotoxic drugs with the targeting ability of antibodies to selectively deliver drugs to cancer cells. The synthesis of ADCs is challenging, and studies in this area show that their therapeutic effect is highly dependent on the chemistries used to connect both functions. Therefore, the linker evolved in recent years from being a simple chemical spacer to a functional structure that controls the potency and selectivity of ADCs. The linker provides a platform to integrate mechanisms to access 2 synthetic homogeneity, stability in circulation and more importantly the installation of chemical units that release the drug as a response to the disease chemical environment. In this study we show for the first time the synthesis of a reactive-oxygen-species (ROS) responsive ADC (VL-DAB31-SN-38) that is highly selective and cytotoxic to B-cell lymphoma (CLBL-1 cell line, IC 50 value of 54.1 nM). The synthesis of this ADC was possible due to the discovery that diazaborines (DABs) are a very effective ROS responsive unit (0.422 and 0.103M -1 S -1 with 100 and 10 equiv. of H 2 O 2 respectively), that is also very stable in buffer (over 14 days at different pHs) and in plasma (over 5 days). DFT calculation performed on this system revealed a favourable energetic profile (ΔGR = -74.3 kcal/mol) similar to the oxidation mechanism of aromatic boronic acids. DABs very fast formation rate and modularity enabled the construction of different ROS responsive linkers featuring self-immolative modules, bioorthogonal functions and bioconjugation handles. These structures were used in the site-selective functionalization of a VL antibody and in the construction of the homogeneous ADC. The enclosed ROS-responsive linker technology based on DABs, is expected to become a valuable tool to prepare stimuli responsive therapeutic materials, as ROS is a very important hallmark in several important diseases.

Antibody–drug conjugates (ADCs) are among the fastest-growing classes of therapeutics in oncology. Although ADCs are in the spotlight, they still present significant engineering challenges. Therefore, there is an urgent need to develop more stable and effective ADCs. Most rabbit light chains have an extra disulfide bridge, that links the variable and constant domains, between Cys80 and Cys171, which is not found in the human or mouse. Thus, to develop a new generation of ADCs, we explored the potential of rabbit-derived VL-single-domain antibody scaffolds (sdAbs) to selectively conjugate a payload to Cys80. Hence, a rabbit sdAb library directed towards canine non-Hodgkin lymphoma (cNHL) was subjected to in vitro and in vivo phage display. This allowed the identification of several highly specific VL-sdAbs, including C5, which specifically target cNHL cells in vitro and present promising in vivo tumor uptake. C5 was selected for SN-38 site-selective payload conjugation through its exposed free Cys80 to generate a stable and homogenous C5-DAB-SN-38. C5-DAB-SN-38 exhibited potent cytotoxicity activity against cNHL cells while inhibiting DNA-TopoI activity. Overall, our strategy validates a platform to develop a novel class of ADCs that combines the benefits of rabbit VL-sdAb scaffolds and the canine lymphoma model as a powerful framework for clinically translation of novel therapeutics for cancer.

Antibody-drug conjugates (ADCs) are an ew class of therapeutics that combine the lethality of potent cytotoxic drugs with the targeting ability of antibodies to selectively deliver drugs to cancer cells.Inthis study we showfor the first time the synthesis of ar eactive-oxygen-species (ROS)-responsive ADC (VL-DAB31-SN-38) that is highly selective and cytotoxic to B-cell lymphoma (CLBL-1 cell line,IC 50 value of 54.1 nM). The synthesis of this ADC was possible due to the discovery that diazaborines (DABs) are avery effective ROSresponsive unit that are also very stable in buffer and in plasma. DFT calculations performed on this system revealed af avorable energetic profile (DGR = À74.3 kcal mol À1 )similar to the oxidation mechanism of aromatic boronic acids.D ABs very fast formation rate and modularity enabled the construction of different ROS-responsive linkers featuring self-immolative modules,b ioorthogonal functions,a nd bioconjugation handles.T hese structures were used in the site-selective functionalization of aV Lantibody domain and in the construction of the homogeneous ADC.