Safety and activity of the first-in-class locked nucleic acid (LNA) miR-221 selective inhibitor in refractory advanced cancer patients: a first-in-human, phase 1, open-label, dose-escalation study

Abstract

Background: We developed a 13-mer locked nucleic acid (LNA) inhibitor of miR-221 (LNA-i-miR-221) with a full phosphorothioate (PS)-modified backbone. This agent downregulated miR-221, demonstrated anti-tumor activity against human xenografts in mice, and favorable toxicokinetics in rats and monkeys. Allometric interspecies scaling allowed us to define the first-in-class LNA-i-miR-221 safe starting dose for the clinical translation.

Methods: In this first-in-human, open-label, dose-escalation phase 1 trial, we enrolled progressive cancer patients (aged ≥ 18 years) with ECOG 0-2 into 5 cohorts. The treatment cycle was based on a 30-min IV infusion of LNA-i-miR-221 on 4 consecutive days. Three patients within the first cohort were treated with 2 cycles (8 infusions), while 14 patients were treated with a single course (4 infusions); all patients were evaluated for phase 1 primary endpoint. The study was approved by the Ethics Committee and Regulatory Authorities (EudraCT 2017-002615-33).

Results: Seventeen patients received the investigational treatment, and 16 were evaluable for response. LNA-i-miR-221 was well tolerated, with no grade 3-4 toxicity, and the MTD was not reached. We recorded stable disease (SD) in 8 (50.0%) patients and partial response (PR) in 1 (6.3%) colorectal cancer case (total SD + PR: 56.3%). Pharmacokinetics indicated non-linear drug concentration increase across the dose range. Pharmacodynamics demonstrated concentration-dependent downregulation of miR-221 and upregulation of its CDKN1B/p27 and PTEN canonical targets. Five mg/kg was defined as the recommended phase II dose.

Conclusions: The excellent safety profile, the promising bio-modulator, and the anti-tumor activity offer the rationale for further clinical investigation of LNA-i-miR-221 (ClinTrials.Gov: NCT04811898).

Keywords: Advanced; Cancer; Clinical trial; First-in-class; First-in-human; LNA-i-miR-221; Non-coding RNA therapeutics; Phase 1; RNA therapeutics; Refractory; miR-221; miRNA; miRNA therapeutics; microRNA.

Fig. 1

CONSORT diagram

Fig. 2

Serum concentration–time (geometric mean) profiles of LNA-i-mirR-221 by dose 0.5, 1, 2, 3 and 5 mg/kg, on day 1, 2, 3 and 4

Fig. 3

Target modulation on PBMCs by LNA-miR-221 inhibitor. Expression levels of miR-221 and CDKN1B were determined by reverse transcription quantitative PCR (RT‐qPCR) in PBMCs isolated from patients at pre-dose (d1) and 24 h after LNA-miR-221 end treatment (d5). Results are expressed as 2^−△Ct or 2^−△△Ct. A and B show modulation of miR-221 and CDKN1B after LNA-miR-221 treatment (paired sample t test, P < 0.05; 95% CI: 95% confidence interval). In C, Western blotting analysis of PTEN and p27 in representative protein samples extracted from PBMCs of patients before and after treatment. D-P. Individual changes of expression level of miR-221 (D-H) and CDKN1B (I-P) in patients from each cohort treated with LNA-i-miR-221 regimen (unpaired sample t test, P: p-value; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001). Error bars represent mean ± standard deviation of each sample among triplicates

Fig. 4

Tumor responses and patient outcomes during the course of this study: A Waterfall plot of CT scan findings according to modified Response Evaluation Criteria in Solid Tumors 1.1. B Swimmer plot of time on study treatment, response status, and survival. C Spider plot of tumor trajectories. D Kaplan–Meier (KM) curve of progression-free survival (PFS)

Fig. 5

Progressive tumor shrinkage in a 60-year-old metastatic colon carcinoma patient with confirmed PR evaluated on three index lesions. The patient underwent left hemicolectomy in 2018 with histological evidence of moderately differentiated intestinal adenocarcinoma, RAS mutated. The patient was treated for stage IV disease with multiple regimens (FOLFOX plus Bevacizumab followed by surgical resection of liver metastases; FOLFIRI plus Aflibercept, FOLFOX, FOLFIRI rechallenges, Trifluridine/Tipiracil, and Regorafenib). The patient had disease progression and was enrolled within cohort V (5 mg/kg for four consecutive days). The RECIST 1.1 assessment after the first cycle with LNA-i-miR-221 showed a clinical benefit. The patient received three subsequent treatment cycles on a compassionate use basis (pre-planned in the study protocol for patients with clinical response). The CT-image shown in the Figure demonstrates disease regression at cycle 1 with deepening response after cycle 4. Further tumor regression of the residual liver lesion has been observed after 7 months of follow-up. At the present (May 2023) the patient is still alive with PS 0