ALN-RSV01 for prevention of bronchiolitis obliterans syndrome after respiratory syncytial virus infection in lung transplant recipients

BACKGROUND

Respiratory syncytial virus (RSV) infection in lung transplant (LTx) patients is associated with an increased incidence of bronchiolitis obliterans syndrome (BOS). ALN-RSV01 is a small interfering RNA targeting RSV replication that was shown in an earlier Phase 2a trial to be safe and to reduce the incidence of BOS when compared with placebo.

METHODS

We performed a Phase 2b randomized, double-blind, placebo-controlled trial in RSV-infected LTx patients to examine the impact of ALN-RSV01 on the incidence of new or progressive BOS. Subjects were randomized (1:1) to receive aerosolized ALN-RSV01 or placebo daily for 5 days.

RESULTS

Of 3,985 symptomatic patients screened, 218 were RSV-positive locally, of whom 87 were randomized to receive ALN-RSV01 or placebo (modified intention-to-treat [mITT] cohort). RSV infection was confirmed by central laboratory in 77 patients (ALN-RSV01, n = 44; placebo, n = 33), which comprised the primary analysis cohort (central mITT [mITTc]). ALN-RSV01 was found to be safe and well-tolerated. At Day 180, in ALN-RSV01-treated patients, compared with placebo, in the mITTc cohort there was a trend toward a decrease in new or progressive BOS (13.6% vs 30.3%, p = 0.058), which was significant in the per-protocol cohort (p = 0.025). Treatment effect was enhanced when ALN-RSV01 was started <5 days from symptom onset, and was observed even without ribavirin treatment. There was no significant impact on viral parameters or symptom scores.

CONCLUSIONS

These results confirm findings of the earlier Phase 2a trial and provide further support that ALN-RSV01 reduces the risk of BOS after RSV in LTx recipients.

Abstract 67: Phase I Safety, Pharmacokinetic, and Pharmacodynamic Results for ALN-PCS, a Novel RNAi Therapeutic for the Treatment of Hypercholesterolemia

Proprotein convertases subtilisin/kexin type 9 (PCSK9) is a member of the proprotein convertase (PC) family of subtilisin-like serine endoproteases that regulates low density lipoprotein receptor (LDLR) levels and function. Murine models and human genetic studies indicate that loss of PCSK9 protein increases LDLR levels while excess PCSK9 decreases LDLR levels. These changes in LDLR protein levels coincide with reciprocal changes in circulating levels of plasma LDL cholesterol (LDL-C). We have developed a highly potent RNA interference (RNAi) therapeutic, ALN-PCS, targeting both intra and extracellular PCSK9 for inhibition through an RNAi mechanism. Pre-clinical data in non-human primate models, indicate that a single intravenous dose of ALN-PCS results in rapid, dose dependent, and significant lowering of liver PCSK9 transcript, plasma PCSK9 protein and subsequently serum LDL-C and ApoB levels, without impacting serum HDL-C. Here we report on interim data from an ongoing Phase 1 trial of ALN-PCS being conducted as a randomized, single-blind, placebo-controlled, single-ascending dose study in healthy volunteer subjects with elevated baseline LDL-C (>116mg/dL) who are not on any lipid lowering therapy. The primary objective of the study is to evaluate the safety and tolerability of a single dose of ALN-PCS, with subjects being enrolled into sequential cohorts of increasing doses. Secondary objectives of the study include characterization of plasma and urine pharmacokinetics of ALN-PCS, assessment of pharmacodynamic effects of the drug on plasma PCSK9 protein levels, and evaluation of clinical efficacy as measured by LDL-C levels. Data from 20 subjects enrolled in five sequential dose cohorts ranging from 0.015 to 0.250 mg/kg in a 3:1 randomization of drug to placebo will be presented. ALN-PCS was safe and well tolerated in this study and there have been no serious adverse events related to study drug administration to date. There have been no drug-related discontinuations from the study and no liver enzyme elevations. A mild, transient rash that resolved spontaneously was observed in three subjects that received ALN-PCS, and in two that received placebo. To date, administration of ALN-PCS resulted in a rapid, dose-dependent, and durable silencing of PCSK9 protein levels in plasma of up to 66% relative to baseline, with a statistically significant mean reduction of 60% at day four in the current high dose group of 0.250 mg/kg (p<0.001). In addition, administration of ALN-PCS resulted in dose-dependent reductions in LDL-C of up to 50% relative to baseline, with a statistically significant mean reduction of 39% at day four (p<0.05) at the 0.250 mg/kg dose level. There was no significant decrease in high-density lipoprotein (HDL). Dosing of further cohorts at the current top dose (0.25 mg/kg) and at a higher dose is planned. Additional data will be presented as available.

RNA interference therapy in lung transplant patients infected with respiratory syncytial virus

RATIONALE

Lower respiratory tract infections due to respiratory syncytial virus (RSV) are associated with development of bronchiolitis obliterans syndrome in lung transplant (LTX) recipients. ALN-RSV01 is a small interfering RNA targeting RSV replication.

OBJECTIVES

To determine the safety and explore the efficacy of ALN-RSV01 in RSV infection.

METHODS

We performed a randomized, double-blind, placebo-controlled trial in LTX recipients with RSV respiratory tract infection. Patients were permitted to receive standard of care for RSV. Aerosolized ALN-RSV01 (0.6 mg/kg) or placebo was administered daily for 3 days. Viral load was determined by quantitative reverse transcriptase-polymerase chain reaction on serial nasal swabs. Patients completed symptom score cards twice daily. Lung function, including the incidence of new-onset or progressive bronchiolitis obliterans syndrome, was recorded at Day 90.

MEASUREMENTS AND MAIN RESULTS

We enrolled 24 patients (ALN-RSV01, n = 16; placebo, n = 8); randomization was stratified by ribavirin use. ALN-RSV01 was well tolerated, with no drug-related serious adverse events or post-inhalation perturbations in lung function. Interpretation of viral measures was confounded by baseline differences between the two groups in viral load and time from symptom onset to first dose. Mean daily symptom scores were lower in subjects receiving ALN-RSV01, and the mean cumulative daily total symptom score was significantly lower with ALN-RSV01 (114.7 ± 63.13 vs. 189.3 ± 99.59, P = 0.035). At Day 90, incidence of new or progressive bronchiolitis obliterans syndrome was significantly reduced in ALN-RSV01 recipients compared with placebo (6.3% vs. 50%, P = 0.027).

CONCLUSIONS

ALN-RSV01 was safe and may have beneficial effects on long-term allograft function in LTX patients infected with RSV. Clinical trial registered with www.clinicaltrials.gov (NCT 00658086).