Safety and efficacy of lirentelimab in patients with refractory indolent systemic mastocytosis: a first-in-human clinical trial.

BACKGROUND: Indolent systemic mastocytosis (ISM) is characterized by excessive mast cell (MC) accumulation and MC-driven signs and symptoms. Currently used therapies are not approved and have limited efficacy. Lirentelimab (AK002) is a monoclonal antibody against sialic acid-binding immunoglobulin-like lectin (Siglec)-8 that inhibits MC activation. OBJECTIVES: To determine the safety, tolerability and efficacy of lirentelimab in reducing the symptoms of ISM. METHODS: At a specialty centre for mastocytosis in Germany, we conducted a phase I first-in-human single-ascending and multidose clinical trial of lirentelimab in patients with ISM. Eligible adults had World Health Organization-confirmed ISM and an unsatisfactory response to available treatment. In part A, patients received a single dose of lirentelimab 0.0003, 0.001, 0.003, 0.01 or 0.03 mg kg-1; in part B, patients received one lirentelimab dose of 0.3 mg kg-1 or 1.0 mg kg-1; and in part C, patients received either 1.0 mg kg-1 lirentelimab every 4 weeks for 6 months or ascending doses of lirentelimab (one dose of 1 mg kg-1 followed by five doses of 3-10 mg kg-1 every 4 weeks). The primary endpoint was safety/tolerability. Secondary endpoints included changes from baseline in Mastocytosis Symptom Questionnaire (MSQ), Mastocytosis Activity Score (MAS) and Mastocytosis Quality of Life Questionnaire (MC-QoL) scores at 2 weeks after the final dose. RESULTS: In 25 patients with ISM (13 in parts A + B and 12 in part C; median age 51 years, 76% female, median 4.6 years from diagnosis), the most common treatment-related adverse events (AEs) were feeling hot (76%) and experiencing a headache (48%). No serious AEs occurred. Median MSQ and MAS symptom severity scores in part C improved (vs. baseline) across all symptoms [MSQ: skin (38-56%), gastrointestinal (49-60%), neurological (47-59%), musculoskeletal (26-27%); MAS: skin (53-59%), gastrointestinal (72-85%), neurological (20-57%), musculoskeletal (25%)]. Median MC-QoL scores improved across all domains: symptoms (39%), social life/functioning (42%), emotions (57%) and skin (44%). CONCLUSIONS: Lirentelimab was generally well tolerated and improved symptoms and quality of life in patients with ISM. The therapeutic potential of lirentelimab should be considered for ISM.

Lirentelimab for severe and chronic forms of allergic conjunctivitis.

BACKGROUND: Allergic conjunctivitis (AC) is an ocular inflammatory disease with symptoms driven by eosinophils and mast cells. Allergic comorbidities are common. Current treatments are often ineffective in severe AC and limited by potential side effects. Lirentelimab is an anti-sialic acid-binding immunoglobulin-like lectin-8 mAb that depletes eosinophils and inhibits mast cells. OBJECTIVE: We sought to determine safety and preliminary efficacy of lirentelimab in an open-label, phase 1b study. METHODS: Patients with chronic, severely symptomatic atopic keratoconjunctivitis, vernal keratoconjunctivitis, and perennial AC, and who had history of topical or systemic corticosteroid use, were enrolled to receive up to 6 monthly lirentelimab infusions (dose 1: 0.3 mg/kg, dose 2: 1 mg/kg, subsequent doses: 1 or 3 mg/kg). Changes from baseline in peripheral blood eosinophils, changes in patient-reported symptoms (measured by daily Allergic Conjunctivitis Symptom Questionnaire, including atopic comorbidities), changes in investigator-reported ocular signs and symptoms (Ocular Symptom Scores), changes in quality of life, and changes in tear cytokine and chemokine levels were assessed. RESULTS: Thirty patients were enrolled (atopic keratoconjunctivitis n = 13, vernal keratoconjunctivitis n = 1, perennial AC n = 16), 87% of whom had atopic comorbidities. After lirentelimab treatment, mean improvement was observed in Allergic Conjunctivitis Symptom Questionnaire score (-61%; 95% CI, -75% to -48%) and Ocular Symptom Scores (-53%; 95% CI, -76% to -31%), consistent across atopic keratoconjunctivitis, vernal keratoconjunctivitis, and perennial AC groups. There was substantial improvement in atopic comorbidities, with -55% (95% CI, -78% to -31%), -50% (95% CI, -82% to -19%), and -63% (95% CI, -87% and -38%) reduction in symptoms of atopic dermatitis, asthma, and rhinitis, respectively. Levels of key mediators of inflammation were reduced in patient tears after lirentelimab treatment. The most common adverse effects were mild to moderate infusion-related reactions. CONCLUSIONS: Lirentelimab was well tolerated, improved severe AC and concomitant atopic symptoms, and reduced inflammatory mediators in patient tears.

Determination of Biopsy Yield That Optimally Detects Eosinophilic Gastritis and/or Duodenitis in a Randomized Trial of Lirentelimab.

BACKGROUND & AIMS: Eosinophilic gastritis (EG) and eosinophilic duodenitis (EoD), characterized by chronic gastrointestinal (GI) symptoms and increased numbers or activation of eosinophils and mast cells in the GI tract, are likely underdiagnosed. We aimed to determine rates of EG and EoD and number of biopsies required to optimize detection using screening data from a randomized trial of lirentelimab (AK002), an antibody against siglec-8 that depletes eosinophils and inhibits mast cells. We also characterized endoscopic features and symptoms of EG and EoD. METHODS: Subjects with moderate-to-severe GI symptoms, assessed daily through a validated patient-reported outcome questionnaire, underwent endoscopy with a systematic gastric and duodenal biopsy protocol and histopathologic evaluation. EG diagnosis required presence of ≥30 eosinophils/high-power field (eos/hpf) in ≥5 hpfs and EoD required ≥30 eos/hpf in ≥3 hpfs. We analyzed diagnostic yields for EG and EoD and histologic, endoscopic, and clinical findings. RESULTS: Of 88 subjects meeting symptom criteria, 72 were found to have EG and/or EoD (EG/EoD), including patients with no prior diagnosis of EG/EoD. We found that GI eosinophilia was patchy and that examination of multiple biopsies was required for diagnosis-an average of only 2.6 per 8 gastric biopsies and 2.2 per 4 duodenal biopsies per subject met thresholds for EG/EoD. Evaluation of multiple nonoverlapping hpfs in each of 8 gastric and 4 duodenal biopsies was required to capture 100% of EG/EoD cases. Neither endoscopic findings nor symptom severity correlated with eosinophil counts. CONCLUSIONS: In an analysis of patients with moderate-to-severe GI symptoms participating in a clinical trial of lirentelimab for EG/EoD, we found eosinophilia to be patchy in gastric and duodenal biopsies. Counting eosinophils in at least 8 gastric and 4 duodenal biopsies is required to identify patients with EG/EoD, so they can receive appropriate treatment. (ClinicalTrials.gov, Number: NCT03496571).

An open-label, proof-of-concept study of lirentelimab for antihistamine-resistant chronic spontaneous and inducible urticaria.

BACKGROUND: Chronic urticaria (CU) is a debilitating mast cell-driven disease, often refractory to standard therapy (ie, antihistamines). Lirentelimab, an anti-sialic acid-binding immunoglobulin-like lectin 8 mAb, selectively inhibits mast cells and depletes eosinophils. OBJECTIVE: We sought to determine safety and efficacy of lirentelimab in patients with CU. METHODS: This phase 2a study enrolled patients with CU refractory to up to 4-fold H1-antihistamine doses. Patients received 6 monthly intravenous doses of lirentelimab (0.3, 1, and up to 3 mg/kg). Primary efficacy end point was change in Urticaria Control Test score at week 22. Urticaria Activity Score weekly average (UAS7) was assessed in patients with chronic spontaneous urticaria (CSU), and Cholinergic UAS7 was used for patients with cholinergic urticaria (CholU). RESULTS: A total of 45 patients were enrolled in 4 cohorts (n = 13 omalizumab-naive CSU, n = 11 omalizumab-refractory CSU, n = 11 CholU, n = 10 symptomatic dermographism). Urticaria Control Test scores increased with lirentelimab across cohorts, with mean changes at week 22 of 11.1 ± 4.1, 4.8 ± 7.0, 6.5 ± 6.2, and 3.4 ± 4.1 and complete response rates (Urticaria Control Test score ≥ 12) of 92%, 36%, 82%, and 40%, respectively. In omalizumab-naive and omalizumab-refractory patients with CSU, disease activity decreased at week 22 (mean UAS7 change, -73% and -47%, respectively), with UAS7 response rates (≥50% reduction) of 77% and 45%, respectively. In patients with symptomatic dermographism, 50% (5 of 10) and 40% (4 of 10) had complete itch and hive resolution by FricTest, respectively, and 100% (7 of 7) evaluable patients with CholU had negative responses to Pulse-Controlled Ergometry exercise test. Most common adverse events included infusion-related reactions (43%; all mild/moderate and transient), nasopharyngitis (21%), and headache (19%). No treatment-related serious adverse events occurred. CONCLUSIONS: Lirentelimab demonstrated activity across 3 forms of antihistamine-refractory CU.

Anti-Siglec-8 Antibody for Eosinophilic Gastritis and Duodenitis.

BACKGROUND: Eosinophilic gastritis and duodenitis are characterized by gastrointestinal mucosal eosinophilia, chronic symptoms, impaired quality of life, and a lack of adequate treatments. Mast-cell activity may contribute to the pathogenesis of the conditions. AK002 (lirentelimab) is an anti-Siglec-8 antibody that depletes eosinophils and inhibits mast cells and that has shown potential in animal models as a treatment for eosinophilic gastritis and duodenitis. METHODS: In this phase 2 trial, we randomly assigned adults who had symptomatic eosinophilic gastritis, eosinophilic duodenitis, or both conditions in a 1:1:1 ratio to receive four monthly infusions of low-dose AK002, high-dose AK002, or placebo. The primary end point was the change in gastrointestinal eosinophil count from baseline to 2 weeks after the final dose; to maximize statistical power, we evaluated this end point in the placebo group as compared with the combined AK002 group. Secondary end points were treatment response (>30% reduction in total symptom score and >75% reduction in gastrointestinal eosinophil count) and the change in total symptom score. RESULTS: Of the 65 patients who underwent randomization, 43 were assigned to receive AK002 and 22 were assigned to receive placebo. The mean percentage change in gastrointestinal eosinophil count was -86% in the combined AK002 group, as compared with 9% in the placebo group (least-squares mean difference, -98 percentage points; 95% confidence interval [CI], -121 to -76; P<0.001). Treatment response occurred in 63% of the patients who received AK002 and in 5% of the patients who received placebo (difference, 58 percentage points; 95% CI, 36 to 74; P<0.001). The mean change in total symptom score was -48% with AK002 and -22% with placebo (least-squares mean difference, -26 percentage points; 95% CI, -44 to -9; P = 0.004). Adverse events associated with AK002 were similar to those with placebo, with the exception of higher percentages of patients having mild-to-moderate infusion-related reactions with AK002 (60% in the combined AK002 group and 23% in the placebo group). CONCLUSIONS: In patients with eosinophilic gastritis or duodenitis, AK002 reduced gastrointestinal eosinophils and symptoms. Infusion-related reactions were more common with AK002 than with placebo. (Funded by Allakos; ENIGMA ClinicalTrials.gov number, NCT03496571.).

Siglec-8 antibody reduces eosinophils and mast cells in a transgenic mouse model of eosinophilic gastroenteritis.

Aberrant accumulation and activation of eosinophils and potentially mast cells (MCs) contribute to the pathogenesis of eosinophilic gastrointestinal diseases (EGIDs), including eosinophilic esophagitis (EoE), gastritis (EG), and gastroenteritis (EGE). Current treatment options, such as diet restriction and corticosteroids, have limited efficacy and are often inappropriate for chronic use. One promising new approach is to deplete eosinophils and inhibit MCs with a monoclonal antibody (mAb) against sialic acid-binding immunoglobulin-like lectin 8 (Siglec-8), an inhibitory receptor selectively expressed on MCs and eosinophils. Here, we characterize MCs and eosinophils from human EG and EoE biopsies using flow cytometry and evaluate the effects of an anti-Siglec-8 mAb using a potentially novel Siglec-8-transgenic mouse model in which EG/EGE was induced by ovalbumin sensitization and intragastric challenge. MCs and eosinophils were significantly increased and activated in human EG and EoE biopsies compared with healthy controls. Similar observations were made in EG/EGE mice. In Siglec-8-transgenic mice, anti-Siglec-8 mAb administration significantly reduced eosinophils and MCs in the stomach, small intestine, and mesenteric lymph nodes and decreased levels of inflammatory mediators. In summary, these findings suggest a role for both MCs and eosinophils in EGID pathogenesis and support the evaluation of anti-Siglec-8 as a therapeutic approach that targets both eosinophils and MCs.

New approaches to hyperkalemia in patients with indications for renin angiotensin aldosterone inhibitors: Considerations for trial design and regulatory approval.

Hyperkalemia is a common clinical problem, especially in patients with chronic kidney disease, diabetes mellitus, or heart failure. Treatment with renin angiotensin aldosterone system inhibitors exacerbates the risk of hyperkalemia in these patients. Concern about hyperkalemia can result in the failure to initiate, suboptimal dosing, or discontinuation of renin angiotensin aldosterone system inhibitor therapy in patients; effective treatments for hyperkalemia might mitigate such undertreatment. New treatments for hyperkalemia in development may offer better efficacy, tolerability and safety profiles than do existing approved treatments. These compounds might enable more eligible patients to receive renin angiotensin aldosterone system inhibitor therapy or to receive renin angiotensin aldosterone system inhibitors at target doses. The evidence needed to support a treatment claim (reduction in serum potassium) differs from that needed to support a prevention claim (preventing hyperkalemia to allow renin angiotensin aldosterone system inhibitor treatment). Thus, several issues related to clinical trial design and drug development need to be considered. This paper summarizes and expands upon a discussion at the Global Cardiovascular Clinical Trialists 2014 Forum and examines methodologic considerations for trials of new potassium binders for the prevention and management of hyperkalemia in patients with renin angiotensin aldosterone system inhibitor indications.

Maintenance of serum potassium with sodium zirconium cyclosilicate (ZS-9) in heart failure patients: results from a phase 3 randomized, double-blind, placebo-controlled trial.

AIMS: Hyperkalaemia in heart failure patients limits use of cardioprotective renin-angiotensin-aldosterone system inhibitors (RAASi). Sodium zirconium cyclosilicate (ZS-9) is a selective potassium ion trap, whose mechanism of action may allow for potassium binding in the upper gastrointestinal tract as early as the duodenum following oral administration. ZS-9 previously demonstrated the ability to reduce elevated potassium levels into the normal range, with a median time of normalization of 2.2 h and sustain normal potassium levels for 28 days in HARMONIZE--a Phase 3, double-blind, randomized, placebo-controlled trial. In the present study we evaluated management of serum potassium with daily ZS-9 over 28 days in heart failure patients from HARMONIZE, including those receiving RAASi therapies. METHODS AND RESULTS: Heart failure patients with evidence of hyperkalaemia (serum potassium ≥5.1 mmol/L, n = 94) were treated with open-label ZS-9 for 48 h. Patients (n = 87; 60 receiving RAASi) who achieved normokalaemia (potassium 3.5-5.0 mmol/L) were randomized to daily ZS-9 (5, 10, or 15 g) or placebo for 28 days. Mean potassium and proportion of patients maintaining normokalaemia during days 8-29 post-randomization were evaluated. Despite RAASi doses being kept constant, patients on 5 g, 10 g, and 15 g ZS-9 maintained a lower potassium level (4.7 mmol/L, 4.5 mmol/L, and 4.4 mmol/L, respectively) than the placebo group (5.2 mmol/L; P<0.01 vs. each ZS-9 group); greater proportions of ZS-9 patients (83%, 89%, and 92%, respectively) maintained normokalaemia than placebo (40%; P < 0.01 vs. each ZS-9 group). The safety profile was consistent with previously reported overall study population. CONCLUSION: Compared with placebo, all three ZS-9 doses lowered potassium and effectively maintained normokalaemia for 28 days in heart failure patients without adjusting concomitant RAASi, while maintaining a safety profile consistent with the overall study population.

A phase 2 study on the treatment of hyperkalemia in patients with chronic kidney disease suggests that the selective potassium trap, ZS-9, is safe and efficient.

Hyperkalemia contributes to significant mortality and limits the use of cardioprotective and renoprotective renin-angiotensin-aldosterone blockers. Current therapies are poorly tolerated and not always effective. Here we conducted a phase 2 randomized, double-blind, placebo-controlled dose-escalation study to assess safety and efficacy of ZS-9. This oral selective cation exchanger that preferentially entraps potassium in the gastrointestinal tract was given to patients with stable Stage 3 chronic kidney disease and hyperkalemia (5.0 to 6.0 mEq/l) during a 2-day period. Of 90 eligible patients with mean baseline serum potassium of 5.1 mEq/l, 30 were randomized to placebo, 12-0.3 g, 24-3 g, or 24 to 10 g of ZS-9 three times daily for 2 days with regular meals. None withdrew and ZS-9 dose-dependently reduced serum potassium. The primary efficacy end point (rate of serum potassium decline in the first 48 h) was met with significance in the 3- and 10-g cohorts. From baseline, mean serum potassium was significantly decreased by 0.92±0.52 mEq/l at 38 h. Urinary potassium excretion significantly decreased with 10-g ZS-9 as compared to placebo at day 2 (+15.8 +/- 21.8 vs. +8.9 +/- 22.9 mEq per 24h) from placebo at day 2. In this short-term study, no serious adverse events were reported; only mild constipation in the 3-g dose group was possibly related to treatment. Thus, ZS-9 was well-tolerated in patients with stable chronic kidney disease and hyperkalemia leading to a rapid, sustained reduction in serum potassium.

Sodium zirconium cyclosilicate in hyperkalemia.

BACKGROUND: Hyperkalemia (serum potassium level, >5.0 mmol per liter) is associated with increased mortality among patients with heart failure, chronic kidney disease, or diabetes. We investigated whether sodium zirconium cyclosilicate (ZS-9), a novel selective cation exchanger, could lower serum potassium levels in patients with hyperkalemia. METHODS: In this multicenter, two-stage, double-blind, phase 3 trial, we randomly assigned 753 patients with hyperkalemia to receive either ZS-9 (at a dose of 1.25 g, 2.5 g, 5 g, or 10 g) or placebo three times daily for 48 hours. Patients with normokalemia (serum potassium level, 3.5 to 4.9 mmol per liter) at 48 hours were randomly assigned to receive either ZS-9 or placebo once daily on days 3 to 14 (maintenance phase). The primary end point was the exponential rate of change in the mean serum potassium level at 48 hours. RESULTS: At 48 hours, the mean serum potassium level had decreased from 5.3 mmol per liter at baseline to 4.9 mmol per liter in the group of patients who received 2.5 g of ZS-9, 4.8 mmol per liter in the 5-g group, and 4.6 mmol per liter in the 10-g group, for mean reductions of 0.5, 0.5, and 0.7 mmol per liter, respectively (P<0.001 for all comparisons) and to 5.1 mmol per liter in the 1.25-g group and the placebo group (mean reduction, 0.3 mmol per liter). In patients who received 5 g of ZS-9 and those who received 10 g of ZS-9, serum potassium levels were maintained at 4.7 mmol per liter and 4.5 mmol per liter, respectively, during the maintenance phase, as compared with a level of more than 5.0 mmol per liter in the placebo group (P<0.01 for all comparisons). Rates of adverse events were similar in the ZS-9 group and the placebo group (12.9% and 10.8%, respectively, in the initial phase; 25.1% and 24.5%, respectively, in the maintenance phase). Diarrhea was the most common complication in the two study groups. CONCLUSIONS: Patients with hyperkalemia who received ZS-9, as compared with those who received placebo, had a significant reduction in potassium levels at 48 hours, with normokalemia maintained during 12 days of maintenance therapy. (Funded by ZS Pharma; ClinicalTrials.gov number, NCT01737697.).

Characterization of structure and function of ZS-9, a K+ selective ion trap.

Hyperkalemia, a condition in which serum potassium ions (K+) exceed 5.0 mmol/L, is a common electrolyte disorder associated with substantial morbidity. Current methods of managing hyperkalemia, including organic polymer resins such as sodium polystyrene sulfonate (SPS), are poorly tolerated and/or not effective. Sodium zirconium cyclosilicate (ZS-9) is under clinical development as an orally administered, non-absorbed, novel, inorganic microporous zirconium silicate compound that selectively removes excess K+ in vivo. The development, structure and ion exchange properties of ZS-9 and its hypothesized mechanism of action are described. Based on calculation of the interatomic distances between the atoms forming the ZS-9 micropores, the size of the pore opening was determined to be ∼ 3 Š(∼ diameter of unhydrated K+). Unlike nonspecific organic polymer resins like SPS, the ZS-9 K+ exchange capacity (KEC) was unaffected by the presence of calcium (Ca2+) or magnesium ions (Mg2+) and showed>25-fold selectivity for K+ over either Ca2+ or Mg2+. Conversely, the selectivity of SPS for K+ was only 0.2-0.3 times its selectivity for Ca2+ or Mg2+in mixed ionic media. It is hypothesized that the high K+ specificity of ZS-9 is attributable to the chemical composition and diameter of the micropores, which possibly act in an analogous manner to the selectivity filter utilized by physiologic K+ channels. This hypothesized mechanism of action is supported by the multi-ion exchange studies. The effect of pH on the KEC of ZS-9 was tested in different media buffered to mimic different portions of the human gastrointestinal tract. Rapid K+ uptake was observed within 5 minutes - mainly in the simulated small intestinal and large intestinal fluids, an effect that was sustained for up to 1 hour. If approved, ZS-9 will represent a novel, first-in-class therapy for hyperkalemia with improved capacity, selectivity, and speed for entrapping K+ when compared to currently available options.

Effect of sodium zirconium cyclosilicate on potassium lowering for 28 days among outpatients with hyperkalemia: the HARMONIZE randomized clinical trial.

IMPORTANCE: Hyperkalemia is a common electrolyte abnormality that may be difficult to manage because of a lack of effective therapies. Sodium zirconium cyclosilicate is a nonabsorbed cation exchanger that selectively binds potassium in the intestine. OBJECTIVE: To evaluate the efficacy and safety of zirconium cyclosilicate for 28 days in patients with hyperkalemia. DESIGN, SETTING, AND PARTICIPANTS: HARMONIZE was a phase 3, multicenter, randomized, double-blind, placebo-controlled trial evaluating zirconium cyclosilicate in outpatients with hyperkalemia (serum potassium ≥5.1 mEq/L) recruited from 44 sites in the United States, Australia, and South Africa (March-August 2014). INTERVENTIONS: Patients (n = 258) received 10 g of zirconium cyclosilicate 3 times daily in the initial 48-hour open-label phase. Patients (n = 237) achieving normokalemia (3.5-5.0 mEq/L) were then randomized to receive zirconium cyclosilicate, 5 g (n = 45 patients), 10 g (n = 51), or 15 g (n = 56), or placebo (n = 85) daily for 28 days. MAIN OUTCOMES AND MEASURES: The primary end point was mean serum potassium level in each zirconium cyclosilicate group vs placebo during days 8-29 of the randomized phase. RESULTS: In the open-label phase, serum potassium levels declined from 5.6 mEq/L at baseline to 4.5 mEq/L at 48 hours. Median time to normalization was 2.2 hours, with 84% of patients (95% CI, 79%-88%) achieving normokalemia by 24 hours and 98% (95% CI, 96%-99%) by 48 hours. In the randomized phase, serum potassium was significantly lower during days 8-29 with all 3 zirconium cyclosilicate doses vs placebo (4.8 mEq/L [95% CI, 4.6-4.9], 4.5 mEq/L [95% CI, 4.4-4.6], and 4.4 mEq/L [95% CI, 4.3-4.5] for 5 g, 10 g, and 15 g; 5.1 mEq/L [95% CI, 5.0-5.2] for placebo; P < .001 for all comparisons). The proportion of patients with mean potassium <5.1 mEq/L during days 8-29 was significantly higher in all zirconium cyclosilicate groups vs placebo (36/45 [80%], 45/50 [90%], and 51/54 [94%] for the 5-g, 10-g, and 15-g groups, vs 38/82 [46%] with placebo; P < .001 for each dose vs placebo). Adverse events were comparable between zirconium cyclosilicate and placebo, although edema was more common in the 15-g group (edema incidence: 2/85 [2%], 1/45 [2%], 3/51 [6%], and 8/56 [14%] patients in the placebo, 5-g, 10-g, and 15-g groups). Hypokalemia developed in 5/51 (10%) and 6/56 patients (11%) in the 10-g and 15-g zirconium cyclosilicate groups, vs none in the 5-g or placebo groups. CONCLUSIONS AND RELEVANCE: Among outpatients with hyperkalemia, open-label sodium zirconium cyclosilicate reduced serum potassium to normal levels within 48 hours; compared with placebo, all 3 doses of zirconium cyclosilicate resulted in lower potassium levels and a higher proportion of patients with normal potassium levels for up to 28 days. Further studies are needed to evaluate the efficacy and safety of zirconium cyclosilicate beyond 4 weeks and to assess long-term clinical outcomes. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT02088073.

A randomized, double-blind, placebo-controlled, multicenter, pilot study of the safety and feasibility of catheter-based intramyocardial injection of AdVEGF121 in patients with refractory advanced coronary artery disease.

BACKGROUND: The experience with direct myocardial injection of adenovirus encoding angiogenic growth factor is limited to invasive surgical approach. Accordingly, we sought to evaluate, for the first time, in a randomized, double-blind, placebo-controlled, phase I pilot study the safety and feasibility of percutaneous catheter-based intramyocardial delivery of a replication-deficient adenovector encoding the 121-amino-acid isoform of vascular endothelial growth factor (AdVEGF121). METHODS: Ten "no-option" patients with severe coronary artery disease were randomized (2:1) to receive AdVEGF121 (4 x 10(10) pu) or placebo as fifteen 100 microL, evenly distributed, endomyocardial injections using a nonflouroscopic, 3-dimensional mapping and injection (NOGA) catheter-based system. RESULTS: Injection procedure was successfully completed in all cases and was associated with no major adverse events. AdVEGF121 was considered potentially associated with a single serious adverse event of transient moderate fever. Elevated postprocedure CK and CK-MB fraction levels were recorded in two placebo-treated and three AdVEGF121-treated patients; all CK measured values were <1.5 times upper limit of normal. All adenoviral cultures (urine and throat swab) were negative 24-hr after dosing, and no significant changes in serial plasma VEGF levels were noted over time. At 12 months follow-up, no cancers, proliferative retinal changes, or significant abnormalities in hepatic, renal or hematological indices were observed. CONCLUSIONS: Percutaneous, catheter-based AdVEGF121 intramyocardial injection is a practical, feasible, and potentially safe approach for intramyocardial gene transfer. A larger randomized, phase II efficacy study is warranted.

A Phase I trial of TNFerade biologic in patients with soft tissue sarcoma in the extremities.

PURPOSE: TNFerade is a second-generation replication-deficient adenovector carrying a transgene encoding human tumor necrosis factor alpha under control of a radiation- induced promoter. The objective of this study was to assess the tolerance of combining TNFerade and radiation therapy in patients with soft tissue sarcomas of the extremity. EXPERIMENTAL DESIGN: TNFerade was administered in combination with single-daily fractionated radiation therapy in 14 patients with soft tissue sarcoma of the extremities. Three escalating dose levels of TNFerade (4 x 10(9) -4 x 10(11) particle units) were planned, given in 1 log increments by intratumoral injections, twice weekly during week 1 and once weekly during weeks 2-5 of radiation therapy. RESULTS: TNFerade was well tolerated with no dose-limiting toxicities noted. Grade 1-2 chills (50.0%), fever (43.0%), fatigue (36.0%), and flu-like symptoms (21.0%) were the most common side effects. Serum-tumor necrosis factor alpha levels were low in all of the patients (<15 pg/mL). No patients had virus-detected blood, sputum, or urine cultures. Of the 13 evaluable patients, 11 received TNFerade preoperatively, and 2 received the treatment for palliation. Eleven patients (85%) showed objective or pathological tumor responses (2 complete and 9 partial), and 1 had stable disease. Partial responses were achieved despite some of these tumors being very large (up to 675 cm(2)). Of the 11 patients who underwent surgery, 10 (91%) showed a pathological complete response/partial response. CONCLUSION: TNFerade + radiation therapy was well tolerated in the treatment of patients with soft-tissue sarcoma of the extremity. The high number of objective responses observed warrants additional studies of this approach in a larger controlled prospective trial.

Regional angiogenesis with vascular endothelial growth factor in peripheral arterial disease: a phase II randomized, double-blind, controlled study of adenoviral delivery of vascular endothelial growth factor 121 in patients with disabling intermittent claudication.

BACKGROUND: "Therapeutic angiogenesis" seeks to improve perfusion by the growth of new blood vessels. The Regional Angiogenesis with Vascular Endothelial growth factor (RAVE) trial is the first major randomized study of adenoviral vascular endothelial growth factor (VEGF) gene transfer for the treatment of peripheral artery disease (PAD). METHODS AND RESULTS: This phase 2, double-blind, placebo-controlled study was designed to test the efficacy and safety of intramuscular delivery of AdVEGF121, a replication-deficient adenovirus encoding the 121-amino-acid isoform of vascular endothelial growth factor, to the lower extremities of subjects with unilateral PAD. In all, 105 subjects with unilateral exercise-limiting intermittent claudication during 2 qualifying treadmill tests, with peak walking time (PWT) between 1 to 10 minutes, were stratified on the basis of diabetic status and randomized to low-dose (4x10(9) PU) AdVEGF121, high-dose (4x10(10) PU) AdVEGF121, or placebo, administered as 20 intramuscular injections to the index leg in a single session. The primary efficacy end point, change in PWT (DeltaPWT) at 12 weeks, did not differ between the placebo (1.8+/-3.2 minutes), low-dose (1.6+/-1.9 minutes), and high-dose (1.5+/-3.1 minutes) groups. Secondary measures, including DeltaPWT, ankle-brachial index, claudication onset time, and quality-of-life measures (SF-36 and Walking Impairment Questionnaire), were also similar among groups at 12 and 26 weeks. AdVEGF121 administration was associated with increased peripheral edema. CONCLUSIONS: A single unilateral intramuscular administration of AdVEGF121 was not associated with improved exercise performance or quality of life in this study. This study does not support local delivery of single-dose VEGF121 as a treatment strategy in patients with unilateral PAD.

Radiation-induced tumour necrosis factor-alpha expression: clinical application of transcriptional and physical targeting of gene therapy.

Promising data are emerging on a new anticancer agent, Ad.EGR-TNF, an adenoviral vector, which contains radio-inducible DNA sequences from the early growth response (EGR1) gene promoter and cDNA for the gene encoding human tumour necrosis factor-alpha. Ad.EGR-TNF combines the well-documented broad-spectrum anticancer activity of TNFalpha with the proven clinical usefulness of radiotherapy. Systemic delivery of the TNFalpha protein has had limited success clinically because of severe dose-limiting toxic effects. This limitation has been overcome by the use of a gene delivery approach, combined with a radiation-inducible promoter to express the TNFalpha protein in the irradiated tumour tissue. Preclinical and early phase I clinical testing indicates that effective concentrations of TNFalpha can be delivered to the tumour site without significant systemic exposure or toxic effects. The combination of radiation and TNFalpha gene delivery has produced striking antitumour effects in model systems in animals. In the clinical setting, potent anticancer activity has been observed with a high rate of complete and partial objective tumour responses. A novel mechanism of destruction of the tumour vasculature seems to be central to this distinct antitumour activity. This review summarises the rationale, mechanistic basis, preclinical data, and preliminary clinical findings for this new treatment model.

Safety of local delivery of low- and intermediate-dose adenovirus gene transfer vectors to individuals with a spectrum of morbid conditions.

To help define the safety profile of the use of adenovirus (Ad) gene transfer vectors in humans, this report summarizes our experience since April 1993 of the local administration of E1(-)/E3(-) Ad vectors to humans using low (<10(9) particle units) or intermediate (10(9)-10(11) particle units) doses. Included in the study are 90 individuals and 12 controls, with diverse comorbid conditions, including cystic fibrosis, colon cancer metastatic to liver, severe coronary artery disease, and peripheral vascular disease, as well as normals. These individuals received 140 different administrations of vector, with up to seven administrations to a single individual. The vectors used include three different transgenes (human cystic fibrosis transmembrane conductance regulator cDNA, E. coli cytosine deaminase gene, and the human vascular endothelial growth factor 121 cDNA) administered by six different routes (nasal epithelium, bronchial epithelium, percutaneous to solid tumor, intradermal, epicardial injection of the myocardium, and skeletal muscle). The total population was followed for 130.4 patient-years. The study assesses adverse events, common laboratory tests, and long-term follow-up, including incidence of death or development of malignancy. The total group incidence of major adverse events linked to an Ad vector was 0.7%. There were no deaths attributable to the Ad vectors per se, and the incidence of malignancy was within that expected for the population. Overall, the observations are consistent with the concept that local administration of low and intermediate doses of Ad vectors appears to be well tolerated.

Analysis of risk factors for local delivery of low- and intermediate-dose adenovirus gene transfer vectors to individuals with a spectrum of comorbid conditions.

In this study we analyze the adverse events and abnormal laboratory parameters following local administration of low (<10(9) particle units) and intermediate (10(9)-10(11) particle units) single and repetitive doses (140 total) of E1(-)E3(-) adenovirus (Ad) gene transfer vectors administered to the respiratory epithelium, solid tumors, skin, myocardium, and skeletal muscle in eight gene transfer trials since April 1993. In the accompanying paper by Harvey et al., (Hum. Gene Ther. 2002; 13:15-63), we conclude that for the total group, no deaths were attributable to the Ad vectors per se, and the incidence of major adverse events likely caused by an Ad vector was 0.7%. The present study analyzes the trials as a group to evaluate risk factors for the adverse events, abnormal values among laboratory parameters, and known deaths. Ten putative risk factors were assessed, including "patient-related" (age, sex, comorbid index and pretherapy anti-Ad antibodies), "vector-related" (dose, route, transgene, and number of vector administrations), and "trial-related" (trial in which the individual was enrolled, and whether surgery was part of the trial). While assessment of each factor individually suggested several possible associations with adverse events, abnormal laboratory parameters, or deaths, multivariate analysis identified only age, comorbid index, and surgery (comorbid index for death; age and surgery for non-death adverse events) as variables significantly associated with increased risk for a major (severity scale 3-4 of 4) adverse event for individuals enrolled in these gene transfer trials. Importantly, multivariate analysis suggested that vector-related parameters, including dose, route, transgene, or number of vector administrations at the doses and routes evaluated in these studies, do not appear to be significant risk factors for a major adverse event. With the caveat that these are phase I, uncontrolled trials, we conclude that (1) there is no definitive risk factor that will clearly predict a major adverse outcome resulting from local administration of low and intermediate doses of Ad gene transfer vectors; and (2) major adverse events in these gene transfer trials are associated primarily with the study population and/or trial procedures, not the Ad vectors themselves. This assessment is consistent with the concept that local administration of low and intermediate doses of Ad gene transfer vectors appears to be well tolerated.

Looking into anti-angiogenic gene therapies for disorders of the eye.

Age-related macular degeneration (AMD) and proliferative diabetic retinopathy (DR) are the most common causes of visual impairment in the developed world. Because the key factor in AMD and DR is aberrant neovascularization in the retina (DR) or in the choroid (AMD), strategies to inhibit abnormal neovascularization represent a compelling therapeutic approach. Here we review various anti-angiogenic strategies for the treatment of ocular neovascular diseases with special emphasis on gene transfer as a way of achieving high, sustained concentrations of anti-angiogenic proteins in the back of the eye without concomitant systemic toxicity.