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.

Abstract 2875: p53 regulation of PDL1 is mediated through miR-34a

Background Although clinical studies have shown promise for targeting PD1/PDL1 signaling in non-small cell lung cancer (NSCLC), little is known of how PDL1 expression is regulated. We previously found that miR-200s directly regulate PDL1; here we show that PDL1 is regulated by miR-34a and p53.

Methods We confirmed that PDL1 is a direct target of miR-34a with western blotting and luciferase assays. We then used in vitro models (p53-/- and p53+/+ HCT116 cells, p53-inducible H1299 cells, and p53-knockdown H460 cells) to determine if p53 regulates PDL1 via miR-34a. Next, we analyzed p53, PDL1, and miR-34a expression in formalin-fixed paraffin-embedded specimens from patients with NSCLC. Finally, we used a p53R172HΔg/+K-rasLA1/+ syngeneic mouse model to deliver miR-34a-loaded liposomes (MRX34) plus radiotherapy and assessed PDL1 expression and tumor-infiltrating lymphocytes (TILs).

Results We found that p53 regulates PDL1 via miR-34a, which directly binds to the PDL1 3′ untranslated region, in NSCLC. Delivery of MRX34 (previously tested in a phase I clinical trial) promoted CD8+ TILs and reduced CD8+PD1+ cells in vivo. Further, MRX34 plus radiotherapy increased CD8+ cell numbers more than either therapy alone. Finally, we showed that miR-34a delivery reduced the numbers of radiation-induced macrophages and T regulatory cells.

Conclusions We identified a novel mechanism by which tumor immune evasion is regulated by p53 and miR-34a via PDL1. Our results suggest that delivery of miR-34a combined with standard therapies, such as radiotherapy, may represent a novel therapeutic approach for lung cancer.

Citation Format: Maria A. Cortez, David Valdecanas, Xiaohong Wang, Cristina Ivan, Heidi Peltier, Huiping Ye, Luiz Araujo, David Carbone, Dipak K. Giri, Ritsuko Komaki, Sunil Krishnan, Ferdinandos Skoulidis, John Heymach, George Calin, Andreas G. Bader, James W. Welsh. p53 regulation of PDL1 is mediated through miR-34a. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2875. doi:10.1158/1538-7445.AM2015-2875

[An early and specific indicator of aminoglycoside nephrotoxicity: isoenzyme B of urinary N-acetyl-beta-D-glucosaminidase (NAG)]

88 patients (aged 55-96 years) with severe infections were treated during ten days with one of four different aminoglycosides: gentamicin, dibekacin, netilmicin (3 mg/kg/day) or amikacin (15 mg/kg/day). Creatinine clearance and urinary N-acetyl-glucosaminidase (NAG) activity were measured daily. In addition, NAG isoenzyme patterns were determined on the day of maximal urinary NAG excretion. Aminoglycoside-induced acute renal failure was more prevalent in the gentamicin group (42.8%) than in the dibekacin, netilmicin or amikacin groups (42.8%, 5.5% and 0% respectively). No relationship was found between total urinary NAG activity and nephrotoxic risk. Conversely, significantly elevated levels (p less than 0.001) of B isoenzyme were detected in the gentamicin group, whereas the highest A and I isoenzyme levels were found in the dibekacin and netilmicin groups. These results suggest that functional enzymuria with preferential urinary excretion of A and I isoenzymes should be distinguished from lesional enzymuria with preferential urinary excretion of the B isoenzyme. According to our data, the NAG-B isoenzyme may possibly be a specific marker of aminoglycoside nephrotoxicity.