Beals, N. | bioRxiv Science

bioRxiv2026

Defining the Immunomodulatory Determinants of 3-mer Oligonucleotides on TLR7 and TLR8 sensing

Chemical modifications such as 2'-O-methyl (2'-OMe) are central to the efficacy and tolerability of RNA therapeutics. We recently identified that 2'-OMe RNA fragments as short as three nucleotides can exert opposing effects on Toll-like receptor 8 (TLR8) sensing in a motif-dependent manner. This discovery raises important considerations for degradation products of chemically modified RNA therapeutics, which may generate such immunologically active fragments. Here, leveraging their short length, we systematically map how base and sugar modifications within 3-mer oligonucleotides regulate TLR7 and TLR8 responses, and we resolve the structural basis for both TLR8 potentiation and TLR7/8 antagonism by RNA fragments. Building on these insights, we report the development of a dual TLR7/8 inhibitory oligonucleotide with therapeutic potential in autoimmune disease. Together, these findings provide unprecedented resolution of the immunomodulatory properties of oligonucleotide modifications on TLR7/8 and establish 3-mer oligonucleotides as the shortest functional class of RNA therapeutics described to date.

immunology↗

bioRxiv2025

Exploiting macropinocytosis for therapeutic intervention in RAS mutant Multiple Myeloma

Roughly 50% of newly diagnosed multiple myeloma (MM) cases harbor KRAS (25%) or NRAS (24%) mutations with an even greater frequency of these mutations observed at relapse. By and large, mutant RAS-driven MM is more resistant to existing therapies including proteasome inhibitors, immunomodulator drugs (IMiDs), and monoclonal anti-CD38 antibodies. In the present study, we demonstrate that mutant RAS-dependent macropinocytosis (MP) can be leveraged for selective delivery of a monobody-drug conjugate (MDC) to mutant RAS MM cells. This MDC delivery platform consists of monobody, a fragment of human fibronectin (FN), used as the carrier to which monomethyl auristatin E (MMAE) is site-specifically conjugated (FN-MMAE). In comparison to standard of care (SoC) therapeutics, FN-MMAE displays a substantially improved anti-tumor effect in vitro and in vivo when administered alone or in combination with SoC treatments. Furthermore, the in vivo safety profile of FN-MMAE is tolerable affording increased drug dosing compared to clinically used ADCs. This MDC platform offers a way of selectively targeting mutant RAS MM and RRMM to potentially improve patient outcomes. Statement of SignificanceRas mutations are present in approximately 50% of MM patients and are associated with poor prognosis and drug resistance. Herein, we describe a novel protein-drug conjugate designed to target selectively mutant RAS harboring MM cells. Our findings uncover a new therapeutic modality for improving the outcomes for patients with mutant Ras MM.

cancer biology↗