Peptides are a powerful drug modality with potential to access difficult targets. This recognition underlies their growth in the global pharmaceutical market, with peptides representing ~8% of drugs approved by the FDA over the past decade. Currently, the peptide therapeutic landscape is evolving, with high-throughput display technologies driving the identification of peptide leads with enhanced diversity. Yet, chemical modifications remain essential for improving the 'drug-like' properties of peptides and ultimately translating leads to market. In this review, we explore two recent therapeutic candidates (semaglutide, a peptide hormone analogue, and MK-0616, an mRNA display-derived candidate) as case studies that highlight general approaches to improving pharmacokinetics (PK) and potency. We also emphasize the critical link between advances in medicinal chemistry and the optimisation of highly efficacious peptide therapeutics.
Advances in small RNA sequencing have revealed diverse small noncoding RNAs (sncRNAs) beyond microRNAs (miRNAs), derived from transfer RNAs (tRNAs), ribosomal RNAs (rRNAs), small nuclear RNAs (snRNAs), and Y RNAs, carrying distinct RNA modifications. These emerging sncRNAs can function beyond RNA interference (RNAi), adopting aptamer-like roles by interacting with Toll-like receptors 7 and 8 (TLR7 and TLR8) via specific sequences, modifications, and structures. We propose a Sequential Activation Hypothesis where initial abnormal sncRNAs - triggered by infections or stresses - activate TLR7/8, leading to autoantibody production against autoantigens like RNA-binding proteins La and Ro. These autoantibody-antigen complexes further promote secondary immunogenic sncRNA production and repetitive TLR7/8 activation, perpetuating a vicious cycle sustaining autoimmunity. TLR7/8's X chromosome location and sex-biased expression contribute to female-dominant autoimmune diseases. Understanding sncRNA-TLR interactions is essential for designing novel therapeutic strategies.