Phase 1 study of MRX34, a liposomal miR-34a mimic, in patients with advanced solid tumours

BACKGROUND

In this first-in-human, Phase 1 study of a microRNA-based cancer therapy, the recommended Phase 2 dose (RP2D) of MRX34, a liposomal mimic of microRNA-34a (miR-34a), was determined and evaluated in patients with advanced solid tumours.

METHODS

Adults with various solid tumours refractory to standard treatments were enrolled in 3 + 3 dose-escalation cohorts and, following RP2D determination, expansion cohorts. MRX34, with oral dexamethasone premedication, was given intravenously daily for 5 days in 3-week cycles.

RESULTS

Common all-cause adverse events observed in 85 patients enrolled included fever (% all grade/G3: 72/4), chills (53/14), fatigue (51/9), back/neck pain (36/5), nausea (36/1) and dyspnoea (25/4). The RP2D was 70 mg/m2 for hepatocellular carcinoma (HCC) and 93 mg/m2 for non-HCC cancers. Pharmacodynamic results showed delivery of miR-34a to tumours, and dose-dependent modulation of target gene expression in white blood cells. Three patients had PRs and 16 had SD lasting ≥4 cycles (median, 19 weeks, range, 11-55).

CONCLUSION

MRX34 treatment with dexamethasone premedication demonstrated a manageable toxicity profile in most patients and some clinical activity. Although the trial was closed early due to serious immune-mediated AEs that resulted in four patient deaths, dose-dependent modulation of relevant target genes provides proof-of-concept for miRNA-based cancer therapy.

CLINICAL TRIAL REGISTRATION

NCT01829971.

MicroRNAs are absorbed in biologically meaningful amounts from nutritionally relevant doses of cow milk and affect gene expression in peripheral blood mononuclear cells, HEK-293 kidney cell cultures, and mouse livers

BACKGROUND

MicroRNAs (miRNAs) regulate genes in animals and plants and can be synthesized endogenously. In milk, miRNAs are encapsulated in exosomes, thereby conferring protection against degradation and facilitating uptake by endocytosis. The majority of bovine miRNAs have nucleotide sequences complementary to human gene transcripts, suggesting that miRNAs in milk might regulate human genes.

OBJECTIVES

We tested the hypotheses that humans absorb biologically meaningful amounts of miRNAs from nutritionally relevant doses of milk, milk-borne miRNAs regulate human gene expression, and mammals cannot compensate for dietary miRNA depletion by endogenous miRNA synthesis.

METHODS

Healthy adults (3 men, 2 women; aged 26-49 y) consumed 0.25, 0.5, and 1.0 L of milk in a randomized crossover design. Gene expression studies and milk miRNA depletion studies were conducted in human cell cultures and mice, respectively. For comparison, feeding studies with plant miRNAs from broccoli were conducted in humans.

RESULTS

Postprandial concentration time curves suggest that meaningful amounts of miRNA (miR)-29b and miR-200c were absorbed; plasma concentrations of miR-1 did not change (negative control). The expression of runt-related transcription factor 2 (RUNX2), a known target of miR-29b, increased by 31% in blood mononuclear cells after milk consumption compared with baseline. When milk exosomes were added to cell culture media, mimicking postprandial concentrations of miR-29b and miR-200c, reporter gene activities significantly decreased by 44% and 17%, respectively, compared with vehicle controls in human embryonic kidney 293 cells. When C57BL/6J mice were fed a milk miRNA-depleted diet for 4 wk, plasma miR-29b concentrations were significantly decreased by 61% compared with miRNA-sufficient controls, i.e., endogenous synthesis did not compensate for dietary depletion. Broccoli sprout feeding studies were conducted as a control and elicited no detectable increase in Brassica-specific miRNAs.

CONCLUSION

We conclude that miRNAs in milk are bioactive food compounds that regulate human genes.

Safety, tolerability, and antiviral effect of RG-101 in patients with chronic hepatitis C: a phase 1B, double-blind, randomised controlled trial

BACKGROUND

miR-122 is an important host factor for hepatitis C virus (HCV) replication. The aim of this study was to assess the safety and tolerability, pharmacokinetics, and antiviral effect of a single dose of RG-101, a hepatocyte targeted N-acetylgalactosamine conjugated oligonucleotide that antagonises miR-122, in patients with chronic HCV infection with various genotypes.

METHODS

In this randomised, double-blind, placebo-controlled, multicentre, phase 1B study, patients were randomly assigned to RG-101 or placebo (7:1). We enrolled men and postmenopausal or hysterectomised women (aged 18-65 years) with chronic HCV genotype 1, 3, or 4 infection diagnosed at least 24 weeks before screening who were either treatment naive to or relapsed after interferon-α based therapy. Patients with co-infection (hepatitis B virus or HIV infection), evidence of decompensated liver disease, or a history of hepatocellular carcinoma were excluded. Randomisation was done by an independent, unblinded, statistician using the SAS procedure Proc Plan. The first cohort received one subcutaneous injection of 2 mg/kg RG-101 or placebo; the second cohort received one subcutaneous injection of 4 mg/kg or placebo. Patients were followed up for 8 weeks (all patients) and up to 76 weeks (patients with no viral rebound and excluding those who were randomised to the placebo group) after randomisation. The primary objective was safety and tolerability of RG-101. This trial was registered with EudraCT, number 2013-002978-49.

FINDINGS

Between June 4, 2014, and Oct 27, 2014, we enrolled 32 patients with chronic HCV genotype 1 (n=16), 3 (n=10), or 4 (n=6) infections. In the first cohort, 14 patients were randomly assigned to receive 2 mg/kg RG-101 and two patients were randomly assigned to receive placebo, and in the second cohort, 14 patients were randomly assigned to receive 4 mg/kg RG-101 and two patients were randomly assigned to receive placebo. Overall, 26 of the 28 patients dosed with RG-101 reported at least one treatment-related adverse event. At week 4, the median viral load reduction from baseline was 4·42 (IQR 3·23-5·00) and 5·07 (4·19-5·35) log₁₀ IU/mL in patients dosed with 2 mg/kg RG-101 or 4 mg/kg RG-101. Three patients had undetectable HCV RNA levels 76 weeks after a single dose of RG-101. Viral rebound at or before week 12 was associated with the appearance of resistance associated substitutions in miR-122 binding regions in the 5' UTR of the HCV genome.

INTERPRETATION

This study showed that one administration of 2 mg/kg or 4 mg/kg RG-101, a hepatocyte targeted N-acetylgalactosamine conjugated anti-miR-122 oligonucleotide, was well tolerated and resulted in substantial viral load reduction in all treated patients within 4 weeks, and sustained virological response in three patients for 76 weeks.

FUNDING

Regulus Therapeutics, Inc.

Determination of the potential bioavailability of plant microRNAs using a simulated human digestion process

SCOPE

The "dietary xenomiR hypothesis" proposes that microRNAs (miRNAs) in foodstuffs survive transit through the mammalian gastrointestinal tract and pass into cells intact to affect gene regulation. However, debate continues as to whether dietary intake poses a feasible route for such exogenous gene regulators. Understanding on miRNA levels during pretreatments of human diet is essential to test their bioavailability during digestion. This study makes the novel first use of an in vitro method to eliminate the inherent complexities and variability of in vivo approaches used to test this hypothesis.

METHODS AND RESULTS

Plant miRNA levels in soybean and rice were measured during storage, processing, cooking, and early digestion using real-time PCR. We have demonstrated for the first time that storage, processing, and cooking does not abolish the plant miRNAs present in the foodstuffs. In addition, utilizing a simulated human digestion system revealed significant plant miRNA bioavailability after early stage digestion for 75 min. Attenuation of plant messenger RNA and synthetic miRNA was observed under these conditions.

CONCLUSION

Even after an extensive pretreatment, plant-derived miRNA, delivered by typical dietary ingestion, has a robustness that could make them bioavailable for uptake during early digestion. The potential benefit of these regulatory molecules in pharma nutrition could be explored further.

Nanoscale delivery systems for microRNAs in cancer therapy

Concomitant with advances in research regarding the role of miRNAs in sustaining carcinogenesis, major concerns about their delivery options for anticancer therapies have been raised. The answer to this problem may come from the world of nanoparticles such as liposomes, exosomes, polymers, dendrimers, mesoporous silica nanoparticles, quantum dots and metal-based nanoparticles which have been proved as versatile and valuable vehicles for many biomolecules including miRNAs. In another train of thoughts, the general scheme of miRNA modulation consists in inhibition of oncomiRNA expression and restoration of tumor suppressor ones. The codelivery of two miRNAs or miRNAs in combination with chemotherapeutics or small molecules was also proposed. The present review presents the latest advancements in miRNA delivery based on nanoparticle-related strategies.

Uptake of MicroRNAs from Exosome-Like Nanovesicles of Edible Plant Juice by Rat Enterocytes

MicroRNAs (miRNAs) are small RNAs present in extracellular vesicles (EVs) that, when transferred to a target cell, affect its biological functions. Plant miRNAs regulate the expression of certain mammalian genes. Here, we characterized EVs in fruit and vegetable juice, and their miRNA cargo, and investigated whether such miRNA-containing EVs could be taken up by mammalian enterocytes in vitro. Using filtration and ultra-centrifugation methods, EVs were purified from commercially available and manually squeezed plant juice. EV morphological features and subcellular localization were analyzed using the NanoSight tracking system and electron microscopy. Plant EV miRNA levels were evaluated using quantitative reverse transcription PCR. For the in vitro EV uptake experiments, rat intestinal epithelial cells (IEC6) were used. Plant EVs shared morphological features with mammalian EVs and contained miR156a-5p, miR166a-3p, and miR168a-5p. EVs were present in the cell sap-filled central vacuoles and were taken up by IEC6 cells. Edible plant cells produce EVs that contain various miRNAs and release them into the central vacuole. The exogenous plant EVs are taken up by mammalian enterocytes in vitro. These findings suggest the possibility that exogenous plant miRNAs carried by EVs can be absorbed via the gastrointestinal tract.

Synthetic microRNA cassette dosing: pharmacokinetics, tissue distribution and bioactivity

MicroRNAs (miRs) are deregulated in cancer and leukemia. Restoring aberrantly downregulated tumor suppressor miRs or antagonizing overexpressed oncogenic miRs in malignant cells by synthetic RNA oligonucleotides represents a potentially novel therapeutic approach in cancer and leukemia. However, given the complex networking and concurrent deregulation of miRs in malignant cells, an effective approach may require concurrent targeting of multiple miRs. Cassette dosing involves simultaneous administration of a mixture of oligonucleotides from the same or different structural classes. However, information on cassette dosing pharmacokinetics, tissue distribution and bioactivity of synthetic miRs is lacking. In this study, three synthetic 2'-methoxyphosphorothioate-miRs (2'-MeOPSmiR16-1, 2'-MeOPSmiR29b and 2'-MeOPSantagomiR155) were administered iv to C57BL/6 mice as a mixture, each at 7.5 mg/kg. Analysis of concentrations of individual miR in plasma and major organ tissues (bone marrow, spleen, liver, brain, heart, kidney and lung) was performed. The mRNA and protein levels of miR's biotargets were monitored sequentially after dosing up to 24 h. Our results demonstrated that these synthetic miRs retain their different individual pharmacokinetic properties and all display three-compartmental pharmacokinetics. 2'-MeOPSmiR16-1 has the longest plasma gamma half-life of 2508 min and lowest total body clearance of 0.0054 L/min·kg, whereas 2'-MeOPSmiR29b has the shortest gamma half-life of 510.6 min and highest total body clearance of 0.042 L/min·kg. The tissue concentrations of all three 2'-MeOPS-modified miR(s)/antagomiR were measurable from 5 min to at least 24 h after dosing, indicating that these concurrently delivered oligonucleotides can reach organ tissues. Importantly, there were biological activities of the concurrently administered miRs which persisted, as shown by the downregulation of specific targets in tested tissues, albeit with variations. Brain was one of the most sensitive tissues with respect to downregulation of mRNA and protein levels of four measured biotargets (e.g., Bcl-2, Mcl-1, DNMT3a and DNMT3b) despite its relatively low miR/antagomiRs levels. We conclude that cassette dosing is applicable to 2'-MeOPS-modified synthetic miRs that are tissue-deliverable and biofunctional without any additional formulation requirement. This study supports future exploration of miR-involved combination therapies.

Pharmacokinetic and Pharmacodynamic Factors Contribute to Synergism between Let-7c-5p and 5-Fluorouracil in Inhibiting Hepatocellular Carcinoma Cell Viability

Pharmacological interventions for hepatocellular carcinoma (HCC) are hindered by complex factors, and rational combination therapy may be developed to improve therapeutic outcomes. Very recently, we have identified a bioengineered microRNA let-7c-5p (or let-7c) agent as an effective inhibitor against HCC in vitro and in vivo. In this study, we sought to identify small-molecule drugs that may synergistically act with let-7c against HCC. Interestingly, we found that let-7c exhibited a strong synergism with 5-fluorouracil (5-FU) in the inhibition of HCC cell viability as manifested by average combination indices of 0.3 and 0.5 in Hep3B and Huh7 cells, respectively. By contrast, coadministration of let-7c with doxorubicin or sorafenib inhibited HCC cell viability with, rather surprisingly, no or minimal synergy. Further studies showed that protein levels of multidrug resistance-associated protein (MRP) ATP-binding cassette subfamily C member 5 (MRP5/ABCC5), a 5-FU efflux transporter, were reduced around 50% by let-7c in HCC cells. This led to a greater degree of intracellular accumulation of 5-FU in Huh7 cells as well as the second messenger cyclic adenosine monophosphate, an endogenous substrate of MRP5. Since 5-FU is an irreversible inhibitor of thymidylate synthetase (TS), we investigated the interactions of let-7c with 5-FU at pharmacodynamic level. Interestingly, our data revealed that let-7c significantly reduced TS protein levels in Huh7 cells, which was associated with the suppression of upstream transcriptional factors as well as other regulatory factors. Collectively, these results indicate that let-7c interacts with 5-FU at both pharmacokinetic and pharmacodynamic levels, and these findings shall offer insight into molecular mechanisms of synergistic drug combinations. SIGNIFICANCE STATEMENT: Combination therapy is a common strategy that generally involves pharmacodynamic interactions. After identifying a strong synergism between let-7c-5p and 5-fluorouracil (5-FU) against hepatocellular carcinoma cell viability, we reveal the involvement of both pharmacokinetic and pharmacodynamic mechanisms. In particular, let-7c enhances 5-FU exposure (via suppressing ABCC5/MRP5 expression) and cotargets thymidylate synthase with 5-FU (let-7c reduces protein expression, whereas 5-FU irreversibly inactivates enzyme). These findings provide insight into developing rational combination therapies based on pharmacological mechanisms.

Functional reconstruction of critical-sized load-bearing bone defects using a Sclerostin-targeting miR-210-3p-based construct to enhance osteogenic activity

A considerable amount of research has focused on improving regenerative therapy strategies for repairing defects in load-bearing bones. The enhancement of tissue regeneration with microRNAs (miRNAs) is being developed because miRNAs can simultaneously regulate multiple signaling pathways in an endogenous manner. In this study, we developed a miR-210-based bone repair strategy. We identified a miRNA (miR-210-3p) that can simultaneously up-regulate the expression of multiple key osteogenic genes in vitro. This process resulted in enhanced bone formation in a subcutaneous mouse model with a miR-210-3p/poly-l-lactic acid (PLLA)/bone marrow-derived stem cell (BMSC) construct. Furthermore, we constructed a model of critical-sized load-bearing bone defects and implanted a miR-210-3p/β-tricalcium phosphate (β-TCP)/bone mesenchymal stem cell (BMSC) construct into the defect. We found that the load-bearing defect was almost fully repaired using the miR-210-3p construct. We also identified a new mechanism by which miR-210-3p regulates Sclerostin protein levels. This miRNA-based strategy may yield novel therapeutic methods for the treatment of regenerative defects in vital load-bearing bones by utilizing miRNA therapy for tissue engineering.

STATEMENT OF SIGNIFICANCE

The destroyed maxillofacial bone reconstruction is still a real challenge for maxillofacial surgeon, due to that functional bone reconstruction involved load-bearing. Base on the above problem, this paper developed a novel miR-210-3p/β-tricalcium phosphate (TCP)/bone marrow-derived stem cell (BMSC) construct (miR-210-3p/β-TCP/BMSCs), which lead to functional reconstruction of critical-size mandible bone defect. We found that the load-bearing defect was almost fully repaired using the miR-210-3p construct. In addition, we also found the mechanism of how the delivered microRNA activated the signaling pathways of endogenous stem cells, leading to the defect regeneration. This miRNA-based strategy can be used to regenerate defects in vital load-bearing bones, thus addressing a critical challenge in regenerative medicine by utilizing miRNA therapy for tissue engineering.

A novel ultrasensitive hybridization-based ELISA method for 2-methoxyphosphorothiolate microRNAs and its in vitro and in vivo application

MicroRNAs (miRNAs) are endogenous, small non-coding RNAs that bind to target mRNAs and regulate their expression. Recent evidence has indicated the involvement of miRNAs in human malignancies. It has been suggested that aberrantly down-regulated or up-regulated miRNAs may be replaced with synthetic miRNAs or antagomiRNAs, respectively, and restore normal cell functions. As therapeutic development requires analytical support, we developed and validated an ultrasensitive and selective assay for quantification of synthetic 2'-methoxyphosphorothiolate-miRNA in mouse plasma and cell lysate for the first time. The method is based on a hybridization-ligation fluorescence enzyme-linked immunosorbent assay and has provided a linear dynamic range of 10-1,000,000 pM for three synthetic miRNAs both singly and in a mixture. The intra- and inter-day coefficients of variation were <20% and the accuracy values nearly 100%. Using this assay, we performed pharmacokinetic studies of three synthetic miRNAs in mice treated with a single i.v. bolus dose of 7.5 mg kg⁻¹. The 2-methoxyphosphorothiolate-miRNAs reached peak concentrations in the μM and nM ranges in plasma and bone marrow, respectively, and remained measurable at 24 h. These concentrations are in a range that shows biological activities. We conclude that this method provides a general and valuable tool for the pharmacologic study and clinical development of synthetic miRNAs.

Time Dependent Distribution of MicroRNA 144 after Intravenous Delivery

BACKGROUND

miR-144 has potential benefits in protecting against myocardial ischemia and suppression of tumor growth. We have previously shown that a single intravenous injection of miR-144 provides potent cardioprotection, but its kinetics and distribution are not known.

METHODS

Single stranded mature miR-144 or Cy3-labelled-miR-144 was delivered into C57/B6 mice by tail vein injection.

RESULTS

After intravenous injection, the signal of Cy3-labelled-miR-144 in the kidney, brain, heart and liver peaks at 60 minutes, and is predominantly localised to the endothelium at that stage. In the kidney and heart, Cy3-labelled-miR-144 signal is detectable within the parenchymal tissues for at least 3 days, after which it starts to decrease, but brain Cy3-miR-144 signal rapidly decreases after 1 hour, and is lost at day 1, with no parenchymal uptake detected. Cy3-miR-144 signal can be detected until day 28 in the liver. Stem loop RTPCR confirmed the temporal pattern shown by miR-144 in kidney, brain and heart, but in liver there was a continuous rise following the initial injection until day 28 with no signs of decrease, suggesting de-novo synthesis.

CONCLUSION

There is early endothelial uptake of injected miR-144 followed by organ-specific distribution and kinetics. In the liver, there appears to be a positive feedback process that leads to continued accumulation of miR-144 that persists for at least 28 days. These observations should be taken into account when designing experiments utilizing parenteral miR-144 and assessing the biology of its actions.

Long non-coding RNA H19 promotes the proliferation, migration and invasion while inhibits apoptosis of hypertrophic scarring fibroblasts by targeting miR-3187-3p/GAB1 axis

BACKGROUND

It had been reported that long non-coding RNA (lncRNA) H19 was associated with the proliferation of fibroblasts. However, the regulatory mechanism of H19 remains unclear. Thus, the study was designed to explore the underlying mechanism of H19 in the process of Hypertrophic scarring (HS).

METHODS

The expression levels of H19, miR-3187-3p, and growth factor receptor binding 2-associated binding protein 1 (GAB1) in HS tissues and HS fibroblasts were measured by real-time quantitative polymerase chain reaction (RT-qPCR) assay. The biological behaviors of HS fibroblasts, such as cell proliferation, apoptosis, migration, and invasion were assessed by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazol-3-ium bromide (MTT), colony formation, flow cytometry, and transwell assays, respectively. The protein expression level was quantified by western blot assay. The interaction association between miR-3187-3p and H19 or GAB1 was predicted by Starbase database analysis and confirmed by dual-luciferase reporter assay, respectively.

RESULTS

H19 was significantly increased in HS tissues and HS fibroblasts. Loss-of-functional experiments revealed that knockdown of H19 inhibited the development of HS. Moreover, silencing of H19 impeded the proliferation, migration, and invasion, while enhanced apoptosis of HS fibroblasts by increasing miR-3187-3p expression. In addition, overexpression of GAB1 could abolish miR-3187-3p overexpression-induced effects on cell proliferation, apoptosis, migration, and invasion of HS fibroblasts. Mechanistically, H19 could act as a sponge of miR-3187-3p to upregulate the expression of GAB1 in HS fibroblasts.

CONCLUSION

Collectively, our results revealed that H19 promoted the proliferation, migration, and invasion, while impeded apoptosis of HS fibroblasts by targeting miR-3187-3p/GAB1 axis.

The Characteristics and Functions of Orally Absorbed Herbal Decoction-Borne Plant MicroRNAs

Herbal decoctions always contain numerous plant microRNAs, and some of these can be absorbed orally to exert cross-kingdom gene regulation. However, little is known about which specific types of herbal decoction-borne plant microRNAs are more likely to be absorbed. Thus, two antiviral herbal decoctions, Qingfei Paidu and Qingre Huashi Kangdu, were administered to human volunteers and rats, respectively, to investigate the characteristics of orally absorbed decoction-borne plant microRNAs. MIR-6240 - 3 p was identified as an absorbed plant microRNA in humans and is most highly expressed in Qingfei Paidu decoction. Therefore, the kinetics of MIR-6240 - 3 p were monitored in humans following the administration of the Qingfei Paidu decoction, and its antiviral effect on human coronavirus type 229E (HCoV-229E) was examined in vitro. There were 586 176 small RNAs identified in Qingfei Paidu decoction, of which 100 276 were orally absorbed by humans. In the Qingre Huashi Kangdu decoction, 124 026 small RNAs were detected, with 7484 being orally absorbed by rats. Logistical repression analysis revealed that absorbable plant small RNAs in both humans and rats presented higher expression levels, greater minimum free energy, and increased AU/UA frequencies compared to nonabsorbable plant small RNAs. The amount of MIR-6240 - 3 p in humans increased between 1 and 3 h after the administration of the Qingfei Paidu decoction. In addition, MIR-6240 - 3 p significantly reduced the RNA copy number and TCID50 of HCoV-229E in vitro. These results suggest that herbal decoction-borne plant small RNAs with a higher expression level, greater minimum free energy, or an increased AU/UA frequency are more likely to be orally absorbed and could potentially mediate cross-kingdom gene regulation.