Precision-activated T-cell engagers targeting HER2 or EGFR and CD3 mitigate on-target, off-tumor toxicity for immunotherapy in solid tumors.

To enhance the therapeutic index of T-cell engagers (TCEs), we engineered masked, precision-activated TCEs (XPAT proteins), targeting a tumor antigen (human epidermal growth factor receptor 2 (HER2) or epidermal growth factor receptor (EGFR)) and CD3. Unstructured XTEN polypeptide masks flank the N and C termini of the TCE and are designed to be released by proteases in the tumor microenvironment. In vitro, unmasked HER2-XPAT (uTCE) demonstrates potent cytotoxicity, with XTEN polypeptide masking providing up to 4-log-fold protection.

Design, Synthesis, and Biological Evaluation of Tubulysin Analogues, Linker-Drugs, and Antibody-Drug Conjugates, Insights into Structure-Activity Relationships, and Tubulysin-Tubulin Binding Derived from X-ray Crystallographic Analysis.

Molecular design, synthesis, and biological evaluation of tubulysin analogues, linker-drugs, and antibody-drug conjugates are described. Among the new discoveries reported is the identification of new potent analogues within the tubulysin family that carry a C11 alkyl ether substituent, rather than the usual ester structural motif at that position, a fact that endows the former with higher plasma stability than that of the latter. Also described herein are X-ray crystallographic analysis studies of two tubulin-tubulysin complexes formed within the α/β interface between two tubulin heterodimers and two highly potent tubulysin analogues, one of which exhibited a different binding mode to the one previously reported for tubulysin M.

Design, Synthesis, and Biological Investigation of Thailanstatin A and Spliceostatin D Analogues Containing Tetrahydropyran, Tetrahydrooxazine, and Fluorinated Structural Motifs.

Thailanstatin A and spliceostatin D, two naturally occurring molecules endowed with potent antitumor activities by virtue of their ability to bind and inhibit the function of the spliceosome, and their natural siblings and designed analogues, constitute an appealing family of compounds for further evaluation and optimization as potential drug candidates for cancer therapies. In this article, the design, synthesis, and biological investigation of a number of novel thailanstatin A analogues, including some accommodating 1,1-difluorocyclopropyl and tetrahydrooxazine structural motifs within their structures, are described. Important findings from these studies paving the way for further investigations include the identification of several highly potent compounds for advancement as payloads for antibody-drug conjugates (ADCs) as potential targeted cancer therapies and/or small molecule drugs, either alone or in combination with other anticancer agents.

Design, Synthesis, and Biological Investigation of Epothilone B Analogues Featuring Lactone, Lactam, and Carbocyclic Macrocycles, Epoxide, Aziridine, and 1,1-Difluorocyclopropane and Other Fluorine Residues.

Despite previous studies within the epothilone field, only one member of this compound family, ixabepilone, made it to approval for clinical use. Recent advances in organic synthesis and medicinal chemistry allow further optimization of lead epothilone analogues aiming to improve their potencies and other pharmacological properties as part of the quest for discovery and development of new anticancer drugs, including antibody-drug conjugates as potential targeted cancer therapies. Herein, we report the design, synthesis, and biological evaluation of a series of new epothilone B analogues equipped with novel structural motifs, including fluorine-containing residues, 12,13-difluorocyclopropyl moieties, mono- and dimethylated macrolactones, and 1-keto macrocyclic systems, as well as two N-substituted ixabepilone analogues in which the 12,13-epoxide and macrolactam NH moieties were replaced, the former with a substituted aziridine moiety and the latter with an NCO-alkyl residue (imide or carbamate).

Total Synthesis and Biological Evaluation of Tiancimycins A and B, Yangpumicin A, and Related Anthraquinone-Fused Enediyne Antitumor Antibiotics.

The family of anthraquinone-fused enediyne antitumor antibiotics was established by the discovery of dynemicin A and deoxy-dynemicin A. It was then expanded, first by the isolation of uncialamycin, and then by the addition to the family of tiancimycins A-F and yangpumicin A. This family of natural products provides opportunities in total synthesis, biology, and medicine due to their novel and challenging molecular structures, intriguing biological properties and mechanism of action, and potential in targeted cancer therapies.