Many cancer type-specific anticancer agents have been developed and significant advances have been made toward precision medicine in cancer treatment. However, traditional or non-specific anticancer drugs are still important for the treatment of many cancer patients whose cancers either do not respond to or have developed resistance to cancer-specific anticancer agents. DNA topoisomerases, especially type IIA topoisomerases, are proven therapeutic targets of anticancer and antibacterial drugs. Clinically successful topoisomerase-targeting anticancer drugs act through topoisomerase poisoning, which leads to replication fork arrest and double-strand break formation. Unfortunately, this unique mode of action is associated with the development of secondary cancers and cardiotoxicity. Structures of topoisomerase-drug-DNA ternary complexes have revealed the exact binding sites and mechanisms of topoisomerase poisons. Recent advances in the field have suggested a possibility of designing isoform-specific human topoisomerase II poisons, which may be developed as safer anticancer drugs. It may also be possible to design catalytic inhibitors of topoisomerases by targeting a certain inactive conformations of these enzymes. Furthermore, identification of various new bacterial topoisomerase inhibitors and regulatory proteins may inspire the discovery of novel human topoisomerase inhibitors. Thus, topoisomerases remain as important therapeutic targets of anticancer agents.

Dual- or multiple-frequency ultrasound stimulation is capable of effectively enhancing the acoustic cavitation effect over single-frequency ultrasound. Potential application of this sonoreactor design has been widely proposed such as on sonoluminescence, sonochemistry enhancement, and transdermal drug release enhancement. All currently available sonoreactor designs employed multiple piezoelectric transducers for generating single-frequency ultrasonic waves separately and then these waves were mixed and interfered in solutions. The purpose of this research is to propose a novel design of generating dual-frequency ultrasonic waves with single piezoelectric elements, thereby enhancing acoustic cavitation. Macroscopic bubbles were detected optically, and they were quantified at either a single-frequency or for different frequency combinations for determining their efficiency for enhancing acoustic cavitation. Visible bubbles were optically detected and hydrogen peroxide was measured to quantify acoustic cavitation. Test water samples with different gas concentrations and different power levels were used to determine the efficacy of enhancing acoustic cavitation of this design. The spectrum obtained from the backscattered signals was also recorded and examined to confirm the occurrence of stable cavitation. The results confirmed that single-element dual-frequency ultrasound stimulation can enhance acoustic cavitation. Under certain testing conditions, the generation of bubbles can be enhanced up to a level of five times higher than the generation of bubbles in single-frequency stimulation, and can increase the hydrogen peroxide production up to an increase of one fold. This design may serve as a useful alternative for future sonoreactor design owing to its simplicity to produce dual- or multiple-frequency ultrasound.

Phosphodiesterase 5A1 (PDE5) is a key target for treating cardiovascular diseases and erectile dysfunction. Here, we report the crystal structure of PDE5 complexed with the sole second generation drug avanafil. Analysis of protein–drug interactions revealed the structural basis of avanafil’s superior isoform selectivity. Moreover, a halogen bonding was observed between avanafil and a backbone carbonyl oxygen of an adjacent α-helix, whose contribution to inhibitory potency illustrates the feasibility of exploiting α-helix backbone in structure-based drug design.

Background and Significance With the emergence of SARS-CoV-2 variants during the global pandemic from 2020 to 2023, there is need for broadly neutralizing antibodies. Due to their small size and unique conformations, nanobodies can recognize protein cavities that are not accessible to conventional antibodies. Methods and Results Here, we used phage display libraries built from dromedary camels to isolate two VHH nanobodies (7A3 and 8A2), which have high affinity for the receptor-binding domain (RBD) of the SARS-CoV-2 spike. Cryo-EM complex structures revealed that 8A2 binds the RBD in its up mode and 7A3 targets a conserved and deeply buried site in the spike regardless of the conformational state of the RBD. At a dose of ≥5 mg/kg, nanobody 7A3 efficiently protected K18-hACE2 transgenic mice from the lethal challenge of SARS-CoV-2 variants B.1.351 or B.1.617. With the addition of omicron variant, a new VHH nanobody (J1B4) was isolated to target the S2 subunit of the SARS-CoV-2 spike that can bind across many variants including omicron. Trispecific nanobodies were made using 7A3, 8A2, and J1B4 which had increased binding signals compared to the nanobodies alone. Using this method, we hope to create a therapeutic that is able to broadly neutralize not only all pre-existing variants of SARS-CoV-2, but also be effective towards future SARS-CoV related variants. Conclusions and Future Directions By combining nanobodies targeting the RBD of the S1 subunit (7A3+8A2) with a nanobody targeting the S2 subunit (J1B4), we can increase the chance of protection against all SARS-CoV-2 infections. Due to the increased protein binding of the trispecific compared to individual nanobodies alone, it shows great promise that the trispecific may be able to enhance its activity across all variants. Nanobody-based therapeutics may be developed as a nasal spray which can be self-administered and inhaled directly to the lungs to treat the infection at its source.