Lumasiran, an RNAi Therapeutic for Primary Hyperoxaluria Type 1.

BACKGROUND: Primary hyperoxaluria type 1 (PH1) is a rare genetic disease caused by hepatic overproduction of oxalate that leads to kidney stones, nephrocalcinosis, kidney failure, and systemic oxalosis. Lumasiran, an investigational RNA interference (RNAi) therapeutic agent, reduces hepatic oxalate production by targeting glycolate oxidase. METHODS: In this double-blind, phase 3 trial, we randomly assigned (in a 2:1 ratio) patients with PH1 who were 6 years of age or older to receive subcutaneous lumasiran or placebo for 6 months (with doses given at baseline and at months 1, 2, 3, and 6). The primary end point was the percent change in 24-hour urinary oxalate excretion from baseline to month 6 (mean percent change across months 3 through 6). Secondary end points included the percent change in the plasma oxalate level from baseline to month 6 (mean percent change across months 3 through 6) and the percentage of patients with 24-hour urinary oxalate excretion no higher than 1.5 times the upper limit of the normal range at month 6. RESULTS: A total of 39 patients underwent randomization; 26 were assigned to the lumasiran group and 13 to the placebo group. The least-squares mean difference in the change in 24-hour urinary oxalate excretion (lumasiran minus placebo) was -53.5 percentage points (P<0.001), with a reduction in the lumasiran group of 65.4% and an effect seen as early as month 1. The between-group differences for all hierarchically tested secondary end points were significant. The difference in the percent change in the plasma oxalate level (lumasiran minus placebo) was -39.5 percentage points (P<0.001). In the lumasiran group, 84% of patients had 24-hour urinary oxalate excretion no higher than 1.5 times the upper limit of the normal range at month 6, as compared with 0% in the placebo group (P<0.001). Mild, transient injection-site reactions were reported in 38% of lumasiran-treated patients. CONCLUSIONS: Lumasiran reduced urinary oxalate excretion, the cause of progressive kidney failure in PH1. The majority of patients who received lumasiran had normal or near-normal levels after 6 months of treatment. (Funded by Alnylam Pharmaceuticals; ILLUMINATE-A ClinicalTrials.gov number, NCT03681184.).

Patisiran, an RNAi Therapeutic, for Hereditary Transthyretin Amyloidosis.

BACKGROUND: Patisiran, an investigational RNA interference therapeutic agent, specifically inhibits hepatic synthesis of transthyretin. METHODS: In this phase 3 trial, we randomly assigned patients with hereditary transthyretin amyloidosis with polyneuropathy, in a 2:1 ratio, to receive intravenous patisiran (0.3 mg per kilogram of body weight) or placebo once every 3 weeks. The primary end point was the change from baseline in the modified Neuropathy Impairment Score+7 (mNIS+7; range, 0 to 304, with higher scores indicating more impairment) at 18 months. Other assessments included the Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) questionnaire (range, -4 to 136, with higher scores indicating worse quality of life), 10-m walk test (with gait speed measured in meters per second), and modified body-mass index (modified BMI, defined as [weight in kilograms divided by square of height in meters]×albumin level in grams per liter; lower values indicated worse nutritional status). RESULTS: A total of 225 patients underwent randomization (148 to the patisiran group and 77 to the placebo group). The mean (±SD) mNIS+7 at baseline was 80.9±41.5 in the patisiran group and 74.6±37.0 in the placebo group; the least-squares mean (±SE) change from baseline was -6.0±1.7 versus 28.0±2.6 (difference, -34.0 points; P<0.001) at 18 months. The mean (±SD) baseline Norfolk QOL-DN score was 59.6±28.2 in the patisiran group and 55.5±24.3 in the placebo group; the least-squares mean (±SE) change from baseline was -6.7±1.8 versus 14.4±2.7 (difference, -21.1 points; P<0.001) at 18 months. Patisiran also showed an effect on gait speed and modified BMI. At 18 months, the least-squares mean change from baseline in gait speed was 0.08±0.02 m per second with patisiran versus -0.24±0.04 m per second with placebo (difference, 0.31 m per second; P<0.001), and the least-squares mean change from baseline in the modified BMI was -3.7±9.6 versus -119.4±14.5 (difference, 115.7; P<0.001). Approximately 20% of the patients who received patisiran and 10% of those who received placebo had mild or moderate infusion-related reactions; the overall incidence and types of adverse events were similar in the two groups. CONCLUSIONS: In this trial, patisiran improved multiple clinical manifestations of hereditary transthyretin amyloidosis. (Funded by Alnylam Pharmaceuticals; APOLLO ClinicalTrials.gov number, NCT01960348 .).

Safety evaluation of 2'-deoxy-2'-fluoro nucleotides in GalNAc-siRNA conjugates.

For oligonucleotide therapeutics, chemical modifications of the sugar-phosphate backbone are frequently used to confer drug-like properties. Because 2'-deoxy-2'-fluoro (2'-F) nucleotides are not known to occur naturally, their safety profile was assessed when used in revusiran and ALN-TTRSC02, two short interfering RNAs (siRNAs), of the same sequence but different chemical modification pattern and metabolic stability, conjugated to an N-acetylgalactosamine (GalNAc) ligand for targeted delivery to hepatocytes. Exposure to 2'-F-monomer metabolites was low and transient in rats and humans. In vitro, 2'-F-nucleoside 5'-triphosphates were neither inhibitors nor preferred substrates for human polymerases, and no obligate or non-obligate chain termination was observed. Modest effects on cell viability and mitochondrial DNA were observed in vitro in a subset of cell types at high concentrations of 2'-F-nucleosides, typically not attained in vivo. No apparent functional impact on mitochondria and no significant accumulation of 2'-F-monomers were observed after weekly administration of two GalNAc-siRNA conjugates in rats for ∼2 years. Taken together, the results support the conclusion that 2'-F nucleotides can be safely applied for the design of metabolically stabilized therapeutic GalNAc-siRNAs with favorable potency and prolonged duration of activity allowing for low dose and infrequent dosing.

Phase 3 Multicenter Study of Revusiran in Patients with Hereditary Transthyretin-Mediated (hATTR) Amyloidosis with Cardiomyopathy (ENDEAVOUR).

PURPOSE: The Phase 3 ENDEAVOUR study evaluated revusiran, an investigational RNA interference therapeutic targeting hepatic transthyretin (TTR) production, for treating cardiomyopathy caused by hereditary transthyretin-mediated (hATTR) amyloidosis. METHODS: Patients with hATTR amyloidosis with cardiomyopathy were randomized 2:1 to receive subcutaneous daily revusiran 500 mg (n = 140) or placebo (n = 66) for 5 days over a week followed by weekly doses. Co-primary endpoints were 6-min walk test distance and serum TTR reduction. RESULTS: Revusiran treatment was stopped after a median of 6.71 months; the study Sponsor prematurely discontinued dosing due to an observed mortality imbalance between treatment arms. Eighteen (12.9%) patients on revusiran and 2 (3.0%) on placebo died during the on-treatment period. Most deaths in both treatment arms were adjudicated as cardiovascular due to heart failure (HF), consistent with the natural history of the disease. A post hoc safety investigation of patients treated with revusiran found that, at baseline, a greater proportion of those who died were ≥ 75 years and showed clinical evidence of more advanced HF compared with those who were alive throughout treatment. Revusiran pharmacokinetic exposures and TTR lowering did not show meaningful differences between patients who died and who were alive. Revusiran did not deleteriously affect echocardiographic parameters, cardiac biomarkers, or frequency of cardiovascular and HF hospitalization events. CONCLUSIONS: Causes for the observed mortality imbalance associated with revusiran were thoroughly investigated and no clear causative mechanism could be identified. Although the results suggest similar progression of cardiac parameters in both treatment arms, a role for revusiran cannot be excluded. CLINICAL TRIAL REGISTRATION: NCT02319005.

Correction to: Phase 3 Multicenter Study of Revusiran in Patients with Hereditary Transthyretin-Mediated (hATTR) Amyloidosis with Cardiomyopathy (ENDEAVOUR).

The original article contained incorrect terminology for one of the cardiac measures; throughout the manuscript and supplementary information 'intraventricular septum wall thickness' should have been given as 'interventricular septum wall thickness'. Corrections should also be noted for Tables 1 and 4: in the Table 1 legend 'Low risk - Neither above at baseline' should read 'Low risk - Neither above threshold at baseline'; in Table 4, the rows 'Mild: eGFR > 60 to < 90 ml/min/1.73 m2' and 'Moderate: eGFR > 30 to < 60 ml/min/1.73 m2' should read 'Mild: eGFR ≥ 60 to < 90 ml/min/1.73 m2' and 'Moderate: eGFR ≥ 30 to < 60 ml/min/1.73 m2', respectively. The original article also contained a mistake in the text of the Pharmacokinetics sub-section of Results; 'There were no apparent differences in revusiran Cmax between patients with mild (eGFR: 30 and < 60 ml/min/1.73 m2) or moderate (eGFR: 60 to < 90 ml/min/1.73 m2) renal impairment when compared with patients with normal (eGFR: ≥ 90 ml/min/1.73 m2) renal function at Weeks 0, 26, and 52 (p > 0.20) (Supplementary Fig. 6)' should read 'There were no apparent differences in revusiran Cmax between patients with mild (eGFR: ≥ 60 to < 90 ml/min/1.73 m2) or moderate (eGFR: ≥ 30 and < 60 ml/min/1.73 m2) renal impairment when compared with patients with normal (eGFR: ≥ 90 ml/min/1.73 m2) renal function at Weeks 0, 26, and 52 (p > 0.20) (Supplementary Fig. 6)'.

The Nonclinical Safety Profile of GalNAc-conjugated RNAi Therapeutics in Subacute Studies.

Short interfering RNAs (siRNAs) and antisense oligonucleotides (ASOs) are the most clinically advanced oligonucleotide-based platforms. A number of N-acetylgalactosamine (GalNAc)-conjugated siRNAs (GalNAc-siRNAs), also referred to as RNA interference (RNAi) therapeutics, are currently in various stages of development, though none is yet approved. While the safety of ASOs has been the subject of extensive review, the nonclinical safety profiles of GalNAc-siRNAs have not been reported. With the exception of sequence differences that confer target RNA specificity, GalNAc-siRNAs are largely chemically uniform, containing limited number of phosphorothioate linkages, and 2'-O-methyl and 2'-deoxy-2'-fluoro ribose modifications. Here, we present the outcomes of short-term (3-5 week) rat and monkey weekly repeat-dose toxicology studies of six Enhanced Stabilization Chemistry GalNAc-siRNAs currently in clinical development. In nonclinical studies at supratherapeutic doses, these molecules share similar safety signals, with histologic findings in the organ of pharmacodynamic effect (liver), the organ of elimination (kidney), and the reticuloendothelial system (lymph nodes). The majority of these changes are nonadverse, partially to completely reversible, correlate well with pharmacokinetic parameters and tissue distribution, and often reflect drug accumulation. Furthermore, all GalNAc-siRNAs tested to date have been negative in genotoxicity and safety pharmacology studies.

Safety and efficacy of RNAi therapy for transthyretin amyloidosis.

BACKGROUND: Transthyretin amyloidosis is caused by the deposition of hepatocyte-derived transthyretin amyloid in peripheral nerves and the heart. A therapeutic approach mediated by RNA interference (RNAi) could reduce the production of transthyretin. METHODS: We identified a potent antitransthyretin small interfering RNA, which was encapsulated in two distinct first- and second-generation formulations of lipid nanoparticles, generating ALN-TTR01 and ALN-TTR02, respectively. Each formulation was studied in a single-dose, placebo-controlled phase 1 trial to assess safety and effect on transthyretin levels. We first evaluated ALN-TTR01 (at doses of 0.01 to 1.0 mg per kilogram of body weight) in 32 patients with transthyretin amyloidosis and then evaluated ALN-TTR02 (at doses of 0.01 to 0.5 mg per kilogram) in 17 healthy volunteers. RESULTS: Rapid, dose-dependent, and durable lowering of transthyretin levels was observed in the two trials. At a dose of 1.0 mg per kilogram, ALN-TTR01 suppressed transthyretin, with a mean reduction at day 7 of 38%, as compared with placebo (P=0.01); levels of mutant and nonmutant forms of transthyretin were lowered to a similar extent. For ALN-TTR02, the mean reductions in transthyretin levels at doses of 0.15 to 0.3 mg per kilogram ranged from 82.3 to 86.8%, with reductions of 56.6 to 67.1% at 28 days (P<0.001 for all comparisons). These reductions were shown to be RNAi-mediated. Mild-to-moderate infusion-related reactions occurred in 20.8% and 7.7% of participants receiving ALN-TTR01 and ALN-TTR02, respectively. CONCLUSIONS: ALN-TTR01 and ALN-TTR02 suppressed the production of both mutant and nonmutant forms of transthyretin, establishing proof of concept for RNAi therapy targeting messenger RNA transcribed from a disease-causing gene. (Funded by Alnylam Pharmaceuticals; ClinicalTrials.gov numbers, NCT01148953 and NCT01559077.).

Effect of an RNA interference drug on the synthesis of proprotein convertase subtilisin/kexin type 9 (PCSK9) and the concentration of serum LDL cholesterol in healthy volunteers: a randomised, single-blind, placebo-controlled, phase 1 trial.

BACKGROUND: Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to LDL receptors, leading to their degradation. Genetics studies have shown that loss-of-function mutations in PCSK9 result in reduced plasma LDL cholesterol and decreased risk of coronary heart disease. We aimed to investigate the safety and efficacy of ALN-PCS, a small interfering RNA that inhibits PCSK9 synthesis, in healthy volunteers with raised cholesterol who were not on lipid-lowering treatment. METHODS: We did a randomised, single-blind, placebo-controlled, phase 1 dose-escalation study in healthy adult volunteers with serum LDL cholesterol of 3·00 mmol/L or higher. Participants were randomly assigned in a 3:1 ratio by computer algorithm to receive one dose of intravenous ALN-PCS (with doses ranging from 0·015 to 0·400 mg/kg) or placebo. The primary endpoint was safety and tolerability of ALN-PCS. Secondary endpoints were the pharmacokinetic characteristics of ALN-PCS and its pharmacodynamic effects on PCSK9 and LDL cholesterol. Study participants were masked to treatment assignment. Analysis was per protocol and we used ANCOVA to analyse pharmacodynamic endpoint data. This trial is registered with ClinicalTrials.gov, number NCT01437059. FINDINGS: Of 32 participants, 24 were randomly allocated to receive a single dose of ALN-PCS (0·015 mg/kg [n=3], 0·045 mg/kg [n=3], 0·090 mg/kg [n=3], 0·150 mg/kg [n=3], 0·250 mg/kg [n=6], or 0·400 mg/kg [n=6]) and eight to placebo. The proportions of patients affected by treatment-emergent adverse events were similar in the ALN-PCS and placebo groups (19 [79%] vs seven [88%]). ALN-PCS was rapidly distributed, with peak concentration and area under the curve (0 to last measurement) increasing in a roughly dose-proportional way across the dose range tested. In the group given 0·400 mg/kg of ALN-PCS, treatment resulted in a mean 70% reduction in circulating PCSK9 plasma protein (p<0·0001) and a mean 40% reduction in LDL cholesterol from baseline relative to placebo (p<0·0001). INTERPRETATION: Our results suggest that inhibition of PCSK9 synthesis by RNA interference (RNAi) provides a potentially safe mechanism to reduce LDL cholesterol concentration in healthy individuals with raised cholesterol. These results support the further assessment of ALN-PCS in patients with hypercholesterolaemia, including those being treated with statins. This study is the first to show an RNAi drug being used to affect a clinically validated endpoint (ie, LDL cholesterol) in human beings. FUNDING: Alnylam Pharmaceuticals.

Rare loss of function variants in the hepatokine gene INHBE protect from abdominal obesity.

Identifying genetic variants associated with lower waist-to-hip ratio can reveal new therapeutic targets for abdominal obesity. We use exome sequences from 362,679 individuals to identify genes associated with waist-to-hip ratio adjusted for BMI (WHRadjBMI), a surrogate for abdominal fat that is causally linked to type 2 diabetes and coronary heart disease. Predicted loss of function (pLOF) variants in INHBE associate with lower WHRadjBMI and this association replicates in data from AMP-T2D-GENES. INHBE encodes a secreted protein, the hepatokine activin E. In vitro characterization of the most common INHBE pLOF variant in our study, indicates an in-frame deletion resulting in a 90% reduction in secreted protein levels. We detect associations with lower WHRadjBMI for variants in ACVR1C, encoding an activin receptor, further highlighting the involvement of activins in regulating fat distribution. These findings highlight activin E as a potential therapeutic target for abdominal obesity, a phenotype linked to cardiometabolic disease.

Single-Dose Pharmacokinetics and Pharmacodynamics of Transthyretin Targeting N-acetylgalactosamine-Small Interfering Ribonucleic Acid Conjugate, Vutrisiran, in Healthy Subjects.

Vutrisiran (ALN-TTRsc02) is a liver-directed, investigational, small interfering ribonucleic acid drug for the treatment of transthyretin (TTR)-mediated amyloidosis. This phase I, randomized, single-blind, placebo-controlled, single ascending dose study evaluated the pharmacodynamics, pharmacokinetics, and safety profile of subcutaneously administered vutrisiran (5-300 mg) in healthy subjects (n = 80). Vutrisiran treatment achieved potent and sustained TTR reduction in a dose-dependent manner, with mean maximum TTR reduction of 57-97%, maintained for ≥ 90 days post dose. Vutrisiran was rapidly absorbed (peak plasma concentration 3-5 hours post dose), had a short plasma half-life (4.2-7.5 hours), and plasma concentrations increased in a dose-proportional manner. Pharmacodynamic and pharmacokinetic results were similar in Japanese and non-Japanese subjects. Vutrisiran had an acceptable safety profile; the most common treatment-related adverse event was mild, transient injection site reactions in four (6.7%) vutrisiran-treated subjects. The favorable pharmacokinetic, pharmacodynamic, and safety results observed here support vutrisiran's continued clinical development.

Association of the transthyretin variant V122I with polyneuropathy among individuals of African ancestry.

Hereditary transthyretin-mediated (hATTR) amyloidosis is an underdiagnosed, progressively debilitating disease caused by mutations in the transthyretin (TTR) gene. V122I, a common pathogenic TTR mutation, is found in 3-4% of individuals of African ancestry in the United States and has been associated with cardiomyopathy and heart failure. To better understand the phenotypic consequences of carrying V122I, we conducted a phenome-wide association study scanning 427 ICD diagnosis codes in UK Biobank participants of African ancestry (n = 6062). Significant associations were tested for replication in the Penn Medicine Biobank (n = 5737) and the Million Veteran Program (n = 82,382). V122I was significantly associated with polyneuropathy in the UK Biobank (odds ratio [OR] = 6.4, 95% confidence interval [CI] 2.6-15.6, p = 4.2 × 10-5), which was replicated in the Penn Medicine Biobank (OR = 1.6, 95% CI 1.2-2.4, p = 6.0 × 10-3) and Million Veteran Program (OR = 1.5, 95% CI 1.2-1.8, p = 1.8 × 10-4). Polyneuropathy prevalence among V122I carriers was 2.1%, 9.0%, and 4.8% in the UK Biobank, Penn Medicine Biobank, and Million Veteran Program, respectively. The cumulative incidence of common hATTR amyloidosis manifestations (carpal tunnel syndrome, polyneuropathy, cardiomyopathy, heart failure) was significantly enriched in V122I carriers compared with non-carriers (HR = 2.8, 95% CI 1.7-4.5, p = 2.6 × 10-5) in the UK Biobank, with 37.4% of V122I carriers having at least one of these manifestations by age 75. Our findings show that V122I carriers are at increased risk of polyneuropathy. These results also emphasize the underdiagnosis of disease in V122I carriers with a significant proportion of subjects showing phenotypic changes consistent with hATTR amyloidosis. Greater understanding of the manifestations associated with V122I is critical for earlier diagnosis and treatment.

Phase 1/2 Study of Lumasiran for Treatment of Primary Hyperoxaluria Type 1: A Placebo-Controlled Randomized Clinical Trial.

BACKGROUND AND OBJECTIVES: In the rare disease primary hyperoxaluria type 1, overproduction of oxalate by the liver causes kidney stones, nephrocalcinosis, kidney failure, and systemic oxalosis. Lumasiran, an RNA interference therapeutic, suppresses glycolate oxidase, reducing hepatic oxalate production. The objective of this first-in-human, randomized, placebo-controlled trial was to evaluate the safety, pharmacokinetic, and pharmacodynamic profiles of lumasiran in healthy participants and patients with primary hyperoxaluria type 1. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This phase 1/2 study was conducted in two parts. In part A, healthy adults randomized 3:1 received a single subcutaneous dose of lumasiran or placebo in ascending dose groups (0.3-6 mg/kg). In part B, patients with primary hyperoxaluria type 1 randomized 3:1 received up to three doses of lumasiran or placebo in cohorts of 1 or 3 mg/kg monthly or 3 mg/kg quarterly. Patients initially assigned to placebo crossed over to lumasiran on day 85. The primary outcome was incidence of adverse events. Secondary outcomes included pharmacokinetic and pharmacodynamic parameters, including measures of oxalate in patients with primary hyperoxaluria type 1. Data were analyzed using descriptive statistics. RESULTS: Thirty-two healthy participants and 20 adult and pediatric patients with primary hyperoxaluria type 1 were enrolled. Lumasiran had an acceptable safety profile, with no serious adverse events or study discontinuations attributed to treatment. In part A, increases in mean plasma glycolate concentration, a measure of target engagement, were observed in healthy participants. In part B, patients with primary hyperoxaluria type 1 had a mean maximal reduction from baseline of 75% across dosing cohorts in 24-hour urinary oxalate excretion. All patients achieved urinary oxalate levels ≤1.5 times the upper limit of normal. CONCLUSIONS: Lumasiran had an acceptable safety profile and reduced urinary oxalate excretion in all patients with primary hyperoxaluria type 1 to near-normal levels. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: Study of Lumasiran in Healthy Adults and Patients with Primary Hyperoxaluria Type 1, NCT02706886.

Evaluation of the safety, tolerability and pharmacokinetics of ALN-RSV01, a novel RNAi antiviral therapeutic directed against respiratory syncytial virus (RSV).

Small interfering RNAs (siRNAs) work through RNA interference (RNAi), the natural RNA inhibitory pathway, to down-regulate protein production by inhibiting targeted mRNA in a sequence-specific manner. ALN-RSV01 is an siRNA directed against the mRNA encoding the N-protein of respiratory syncytial virus (RSV) that exhibits specific in vitro and in vivo anti-RSV activity. The results of two safety and tolerability studies with ALN-RSV01 involving 101 healthy adults (65 active, 36 placebo, single- and multiple dose, observer-blind, randomized dose-escalation) are described. Intranasal administration of ALN-RSV01 was well tolerated over a dose range up through 150mg as a single dose and for five daily doses. Adverse events were similar in frequency and severity to placebo (normal saline) and were transient, mild to moderate, with no dose-dependent trend. The frequency or severity of adverse events did not increase with increasing ALN-RSV01 exposure. All subjects completed all treatments and assessments with no early withdrawals or serious adverse events. Physical examinations, vital signs, ECGs and laboratory tests were normal. Systemic bioavailability of ALN-RSV01 was minimal. ALN-RSV01 appears safe and well tolerated when delivered intranasally and is a promising therapeutic candidate for further clinical development.

Treatment of psoriasis with alefacept: correlation of clinical improvement with reductions of memory T-cell counts.

OBJECTIVE: To examine the relationship between the pharmacodynamic and antipsoriatic effects of alefacept, a biologic agent that targets CD4+ and CD8+ memory T cells. DESIGN: Randomized, double-blind, placebo-controlled study of 3 parallel groups. SETTING: Fifty-one study centers. PATIENTS: Five hundred fifty-three patients with chronic plaque psoriasis. INTERVENTIONS: Patients were randomized (1:1:1) to 1 of the following 3 cohorts: alefacept, 7.5 mg, in both courses (cohort 1); alefacept, 7.5 mg, in the first course and placebo in the second course (cohort 2); or placebo in the first course and alefacept, 7.5 mg, in the second course (cohort 3). In each course, alefacept or placebo was administered by intravenous bolus once weekly for 12 weeks, followed by 12 weeks of observation. MAIN OUTCOME MEASURES: Circulating lymphocyte levels and the Psoriasis Area Severity Index. RESULTS: One or 2 courses of alefacept reduced CD4+ and CD8+ memory T-cell counts, while sparing the naive population. At 12 weeks after the last dose of alefacept in courses 1 and 2, 88% and 83% of patients, respectively, had CD4+ cell counts greater than the lower limit of normal. In course 1, alefacept-treated patients with the largest decreases in memory T-cell counts experienced the greatest reductions in disease activity (P<.001). The duration of clinical benefit seemed to be longer among patients who had the greatest reduction in CD4+ and CD8+ memory T-cell counts. CONCLUSIONS: One or 2 courses of intravenous alefacept reduced circulating memory T-cell counts while sparing the naïve T-cell population. The reductions in memory T-cell counts were related to all measures of disease activity evaluated and the duration of response to therapy, suggesting that prolonged remissions of psoriasis can be attained with reduction of the pathogenic T-cell count.

First-in-humans trial of an RNA interference therapeutic targeting VEGF and KSP in cancer patients with liver involvement.

UNLABELLED: RNA interference (RNAi) is a potent and specific mechanism for regulating gene expression. Harnessing RNAi to silence genes involved in disease holds promise for the development of a new class of therapeutics. Delivery is key to realizing the potential of RNAi, and lipid nanoparticles (LNP) have proved effective in delivery of siRNAs to the liver and to tumors in animals. To examine the activity and safety of LNP-formulated siRNAs in humans, we initiated a trial of ALN-VSP, an LNP formulation of siRNAs targeting VEGF and kinesin spindle protein (KSP), in patients with cancer. Here, we show detection of drug in tumor biopsies, siRNA-mediated mRNA cleavage in the liver, pharmacodynamics suggestive of target downregulation, and antitumor activity, including complete regression of liver metastases in endometrial cancer. In addition, we show that biweekly intravenous administration of ALN-VSP was safe and well tolerated. These data provide proof-of-concept for RNAi therapeutics in humans and form the basis for further development in cancer. SIGNIFICANCE: The fi ndings in this report show safety, pharmacokinetics, RNAi mechanism of action, and clinical activity with a novel fi rst-in-class LNP-formulated RNAi therapeutic in patients with cancer. The ability to harness RNAi to facilitate specifi c multitargeting, as well as increase the number of druggable targets, has important implications for future drug development in oncology.

A status report on RNAi therapeutics.

Fire and Mello initiated the current explosion of interest in RNA interference (RNAi) biology with their seminal work in Caenorhabditis elegans. These observations were closely followed by the demonstration of RNAi in Drosophila melanogaster. However, the full potential of these new discoveries only became clear when Tuschl and colleagues showed that 21-22 bp RNA duplexes with 3" overhangs, termed small interfering (si)RNAs, could reliably execute RNAi in a range of mammalian cells. Soon afterwards, it became clear that many different human cell types had endogenous machinery, the RNA-induced silencing complex (RISC), which could be harnessed to silence any gene in the genome. Beyond the availability of a novel way to dissect biology, an important target validation tool was now available. More importantly, two key properties of the RNAi pathway - sequence-mediated specificity and potency - suggested that RNAi might be the most important pharmacological advance since the advent of protein therapeutics. The implications were profound. One could now envisage selecting disease-associated targets at will and expect to suppress proteins that had remained intractable to inhibition by conventional methods, such as small molecules. This review attempts to summarize the current understanding on siRNA lead discovery, the delivery of RNAi therapeutics, typical in vivo pharmacological profiles, preclinical safety evaluation and an overview of the 14 programs that have already entered clinical practice.

CD4+ T-cell-directed antibody responses are maintained in patients with psoriasis receiving alefacept: results of a randomized study.

BACKGROUND: Alefacept, human LFA-3/IgG(1) fusion protein, selectively reduces memory-effector (CD45RO(+)) T cells, a source of the pathogenic mediators of psoriasis. OBJECTIVE: To evaluate the effect of alefacept on immune function, T-cell-dependent humoral responses to a neoantigen (PhiX174) and recall antigen (tetanus toxoid) were assessed. METHODS: Patients with psoriasis were randomized to the control group or to receive alefacept (7.5 mg intravenously weekly for 12 weeks). The alefacept group received PhiX174 immunizations at weeks 6, 12, 20, and 26 and tetanus toxoid at week 21; control subjects received PhiX174 at weeks 6 and 12 and tetanus at week 10. RESULTS: Mean anti-PhiX174 titers were comparable in both groups. There was no difference in the percentage of responders (anti-PhiX174 IgG >/=30% of the total anti-PhiX174) between the alefacept group and the control group (86% and 82%, respectively; P =.73). The percentage of patients with anti-tetanus toxoid titer increases >/=2 times baseline also was similar (alefacept, 89%; control 91%). CONCLUSION: A single 12-week course of alefacept did not impair primary or secondary antibody responses to a neoantigen or memory responses to a recall antigen. The selective immunomodulatory effect of alefacept against a potentially pathogenic T-cell subset is associated with maintenance of a significant aspect of immune function (antibody response) to fight infection and respond to vaccinations.

Alefacept treatment in psoriatic arthritis: reduction of the effector T cell population in peripheral blood and synovial tissue is associated with improvement of clinical signs of arthritis.

OBJECTIVE: To investigate whether alefacept (a fully human lymphocyte function-associated antigen 3 [LFA-3]/IgG1 fusion protein that blocks the LFA-3/CD2 interaction) is able to reduce the signs and symptoms of joint inflammation in patients with active psoriatic arthritis (PsA). METHODS: Eleven patients with active PsA were treated with alefacept for 12 weeks in an open-label and explorative study. Clinical joint assessment and laboratory assessments were performed at baseline and after 4, 9, 12, and 16 weeks of treatment. Serial synovial tissue (ST) biopsy specimens from an inflamed index joint (knee, ankle, wrist, or metacarpophalangeal joint) were obtained by arthroscopy at baseline and after 4 and 12 weeks of treatment. RESULTS: At the completion of treatment, 6 of 11 patients (55%) fulfilled the Disease Activity Score (DAS) response criteria. Nine patients (82%) fulfilled the DAS response criteria at any point during the study. There was a statistically significant reduction in CD4+ lymphocytes (P < 0.05), CD8+ lymphocytes (P = 0.05), and CD68+ macrophages (P < 0.02) in the ST after 12 weeks of treatment compared with baseline. The ST and peripheral blood of those patients fulfilling the DAS response criteria contained more CD45RO+ cells at baseline and displayed a significant reduction in these cells compared with nonresponding patients. CONCLUSION: The changes in ST, together with the improvement in clinical joint scores, after treatment with alefacept support the hypothesis that T cell activation plays an important role in this chronic inflammatory disease. Furthermore, since alefacept, a T cell-specific agent, led to decreased macrophage infiltration, the data indicate that T cells are highly involved in synovial inflammation in PsA.