Jingfang Ju

Background: Resistance to 5-fluorouracil (5-FU)-based chemotherapy is a major clinical obstacle in colorectal cancer (CRC), highlighting the urgent need to overcome established resistance mechanisms. MicroRNA-based therapeutics have emerged as compelling candidates in this context, given their inherently pleiotropic mode of action; however, their clinical translation remains hindered by poor stability and suboptimal delivery. Methods: To address these limitations, Gem-miR-15a, a unique gemcitabine-modified tumor-suppressor microRNA-15a was designed to synergistically integrate the tumor-suppressive activity of miR-15a with the chemotherapeutic potency of gemcitabine into a single molecular entity. Therapeutic efficacy of Gem-miR-15a was evaluated across a spectrum of preclinical models, including parental and drug-resistant CRC cell lines, 3D tumor spheroids, patient-derived organoids and in vivo metastatic models. Cell viability, apoptosis and cell cycle analyses were performed, along with RNA sequencing and protein validation. Statistical analyses were conducted using Student’s t-test or two-way ANOVA with mixed effects, and data were presented as mean ± SD. Results: Gem-miR-15a exhibited potent anti-proliferative activity with IC ₅₀ values in the low nanomolar range, achieving ~ 100-5000-fold greater potency relative to 5-FU and oxaliplatin. Importantly, it retained efficacy in both 5-FU- and oxaliplatin-resistant CRC models, effectively overcoming acquired chemoresistance. Mechanistically, Gem-miR-15a induced S-phase cell cycle arrest, eliminated the G2-phase cell population, and triggered apoptosis, accompanied by suppression of key oncogenic targets including WEE1, CHK1, YAP1 and BMI1. RNA-seq analysis further demonstrated modulation of pathways such as p53 signaling and reversal of resistance-associated gene expression, that were corroborated at the protein level. In vivo , Gem-miR-15a significantly reduced tumor growth at a dose ~ 12-fold lower than gemcitabine, with no observable toxicity. Conclusion: Gem-miR-15a represents a potent, multi-targeted therapeutic strategy capable of overcoming chemoresistance in CRC. Its enhanced stability, effective delivery and robust efficacy across resistant models and a favorable safety profile highlight its strong potential for clinical translation.

Background: Resistance to 5-fluorouracil (5-FU)-based chemotherapy is a major clinical obstacle in colorectal cancer (CRC), highlighting the urgent need to overcome established resistance mechanisms. MicroRNA-based therapeutics have emerged as compelling candidates in this context, given their inherently pleiotropic mode of action; however, their clinical translation remains hindered by poor stability and suboptimal delivery. Methods: To address these limitations, Gem-miR-15a, a unique gemcitabine-modified tumor-suppressor microRNA-15a was designed to synergistically integrate the tumor-suppressive activity of miR-15a with the chemotherapeutic potency of gemcitabine into a single molecular entity. Therapeutic efficacy of Gem-miR-15a was evaluated across a spectrum of preclinical models, including parental and drug-resistant CRC cell lines, 3D tumor spheroids, patient-derived organoids and in vivo metastatic models. Cell viability, apoptosis and cell cycle analyses were performed, along with RNA sequencing and protein validation. Statistical analyses were conducted using Student’s t-test or two-way ANOVA with mixed effects, and data were presented as mean ± SD. Results: Gem-miR-15a exhibited potent anti-proliferative activity with IC ₅₀ values in the low nanomolar range, achieving ∼100-5000-fold greater potency relative to 5-FU and oxaliplatin. Importantly, it retained efficacy in both 5-FU- and oxaliplatin-resistant CRC models, effectively overcoming acquired chemoresistance. Mechanistically, Gem-miR-15a induced S-phase cell cycle arrest, eliminated the G2-phase cell population, and triggered apoptosis, accompanied by suppression of key oncogenic targets including WEE1, CHK1, YAP1 and BMI1. RNA-seq analysis further demonstrated modulation of pathways such as p53 signaling and reversal of resistance-associated gene expression, that were corroborated at the protein level. In vivo , Gem-miR-15a significantly reduced tumor growth at a dose ∼12-fold lower than gemcitabine, with no observable toxicity. Conclusion: Gem-miR-15a represents a potent, multi-targeted therapeutic strategy capable of overcoming chemoresistance in CRC. Its enhanced stability, effective delivery and robust efficacy across resistant models and a favorable safety profile highlight its strong potential for clinical translation. Graphical

Purpose Evaluating the safety and tolerability of 5-FU-miR-15a (CR-001) in adults with relapsed or refractory acute myeloid leukemia (R/R AML) in a phase I dose-escalation study (EudraCT number: 2021-006332-46). Patients and Methods A standard 3+3 dose-escalation study design was employed. Patients received intravenous (IV) administrations of the synthetic double-stranded mimic of miR-15a (miRNA) CR-001 of 7.5 mg, 11.25 mg, 15 mg and 18.75 mg/administration, weekly dosing. Each patient was dosed on a single dose level. The formulation included a fixed dose of GMP-grade linear polyethyleneimine (PEI; α-Methyl-ω-hydroxy-poly[(iminioethylene)chloride]; Poly[imino(1,2-ethanediyl)]; CAS Number 26913-06-4; EC Number 608-018-6) as the excipient: 15 mg of PEI with 7.5 mg CR-001, and 20 mg of PEI with all higher dose levels. Glucose was added to stabilize the miRNA/PEI complexes. Biomarker analysis was performed using mass cytometry (CyTOF) on peripheral blood and bone marrow samples to quantify surface and intracellular protein expression at the single-cell level. Results A total of 11 patients with R/R AML (median age: 74 years; all classified as adverse risk per ELN 2022) received a cumulative 66 intravenous doses of CR-001 (range: 1–16 doses; median: 5) across the four dose levels. The treatment was well-tolerated. One patient demonstrated a partial clinical response, with resolution of extramedullary pericardial AML after four doses. Among the 10 evaluable patients, six achieved stable disease (SD) according to ELN criteria after four infusions. Single-cell profiling mass cytometry revealed molecular activity of CR-001 on known targets of miR-15a (e.g., BMI1, WEE1 and MCL-1) beginning at the lowest dose level (7.5 mg). Concurrently, an increase in BAX, a pro-apoptotic marker, was observed following treatment. Conclusions CR-001 was well tolerated and demonstrated biological activity as evidenced by target modulation and disease stabilization in R/R AML patients. Biological activity was observed starting at the lowest dose level (7.5 mg/administration), with initial signs of clinical efficacy at 11.25 mg per administration. This trial was closed prematurely due to funding constraints, however, based on these findings further development is warranted, possibly in therapy combinations.

Chemoresistance and inefficient therapeutic efficacies in triple-negative breast cancers (TNBCs) are among the major clinical problems in breast cancers. A potential new method to sensitize these tumors to current treatment options is, therefore, urgent and necessary. Our previous studies demonstrated that miR-489 serves as one of the top tumor-suppressing miRs and features downregulated expression in metastatic TNBCs and that the restoration of miR-489 expression in TNBCs effectively inhibits the metastatic potentials of TNBCs both in vitro and in vivo. The chemical modification of miR-489 (CMM489) through the replacement of uracil with 5-FU further enhances the therapeutic potential of miR-489. In the present study, we tested the effects of CMM489 in synergizing DNA damage response (DDR) inhibitors such as PARP inhibitors. CMM489 is particularly effective in sensitizing TNBC cell lines with inherent resistance to PARP inhibitors regardless of BRCA mutation status. One of the anti-cancer mechanisms through which CMM489 synergizes with PARP inhibitors is the blockade of homologous recombination (HR) in TNBC cells upon DNA damage. The results of this study highlight the potential use of CMM489 in combination treatments with PARP inhibitors in TNBCs.