Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) continues to be a global threat due to its ability to evolve and generate new subvariants, leading to new waves of infection. Additionally, other coronaviruses like Middle East respiratory syndrome coronavirus (MERS-CoV, formerly known as hCoV-EMC), which first emerged in 2012, persist and continue to present a threat of severe illness to humans. The continued identification of novel coronaviruses, coupled with the potential for genetic recombination between different strains, raises the possibility of new coronavirus clades of global concern emerging. As a result, there is a pressing need for pan-CoV therapeutic drugs and vaccines. After the extensive optimization of an HCV protease inhibitor screening hit, a novel 3CLPro inhibitor (MK-7845) was discovered and subsequently profiled. MK-7845 exhibited nanomolar in vitro potency with broad spectrum activity against a panel of clinical SARS-CoV-2 subvariants and MERS-CoV. Furthermore, when administered orally, MK-7845 demonstrated a notable reduction in viral burdens by >6 log orders in the lungs of transgenic mice infected with SARS-CoV-2 (K18-hACE2 mice) and MERS-CoV (K18-hDDP4 mice).

LIM domain kinase 1 (LIMK1) has been identified as a promising therapeutic target for a variety of conditions, such as chronic pain, open-angle glaucoma, various cancers, schizophrenia, and Fragile X syndrome. However, identifying inhibitors that selectively inhibit LIMK1 over LIM domain kinase 2 (LIMK2) has proven to be challenging. A viable strategy to overcome this difficulty is the development of covalent inhibitors, which can offer both potency and selectivity for LIMK1 due to a reactive cysteine, C349, near the active site absent in its paralog LIMK2. Here we identify an irreversible covalent inhibitor of LIMK1 (cLIMK1i), which is highly selective for LIMK1 over both LIMK2 and a panel of over 100 kinases. A crystal structure of LIMK1 soaked with cLIMK1i reveals it is a type I inhibitor occupying the ATP-binding site with its acrylamide moiety oriented toward the P-loop where C349 resides. Computational modeling supports that the P-loop of LIMK1 can adopt a conformation compatible with covalent bond formation. Biochemical and biophysical characterization of the interaction of cLIMK1i with LIMK1 demonstrates that the covalent bond with LIMK1-C349 is essential for its potent inhibition. These results support covalent inhibition of LIMK1 as a viable strategy for selectively inhibiting LIMK1 over LIMK2 and other kinases.

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) continues to be a global threat due to its ability to evolve and generate new subvariants, leading to new waves of infection. Additionally, other coronaviruses like Middle East respiratory syndrome coronavirus (MERS-CoV, formerly known as hCoV-EMC) which first emerged in 2012, persists and continues to present a threat of severe illness to humans. The continued identification of novel coronaviruses, coupled with the potential for genetic recombination between different strains, raises the possibility of new coronavirus clades of global concern emerging. As a result, there is a pressing need for pan-CoV therapeutic drugs and vaccines. After extensive optimization of an HCV protease inhibitor screening hit, a novel 3CLPro inhibitor (MK-7845) was discovered and subsequently profiled. MK-7845 exhibited nanomolar in vitro potency with broad spectrum activity against a panel of clinical SARS-CoV-2 subvariants and MERS-CoV. Furthermore, when administered orally, MK-7845 demonstrated a notable reduction of viral burdens by >6 log orders in the lungs of transgenic mice infected with SARS-CoV-2 (K18-hACE2 mice) and MERS-CoV (K18-hDDP4 mice).