Use of real-world evidence in regulatory decisions for rare diseases in the United States-Current status and future directions.

Following the release of the framework for the Real-World Evidence (RWE) Program, the US Food and Drug Administration (FDA) is actively evaluating and exploring ways to optimize the utility of real-world data (RWD) and RWE to support regulatory decision making. For rare conditions, conducting traditional randomized clinical trials may not always be feasible, and RWD and RWE have played and will continue to play an important role. We use three case examples-cerliponase alfa, asfotase alfa, and uridine triacetate-to illustrate how RWD from disease registries, medical records with chart review, and literature, respectively, have been used to generate RWE to support regulatory decisions for selected rare diseases. These examples highlight the need for improving data reliability and quality in existing data to expand use of RWD and RWE beyond "hard endpoints" and standardizing data collection for outcome measures in patient registries to expand its utility. We also discuss a recent FDA guidance for using RWE in supporting rare disease drug development, including its recommendations about using natural history studies as external control groups for single-arm interventional trials. The external control group needs to be comparable with the treated group. Selection bias and confounding are major concerns because of lack of randomization and unrecognized baseline differences. Use of valid epidemiological approaches can reduce these biases. Lastly, we discuss future directions to expand the use of RWD and RWE to support orphan drug approvals, including the need for including patient experience data as an important source of RWD.

Concurrent erythropoietin and hypothermia treatment improve outcomes in a term nonhuman primate model of perinatal asphyxia.

BACKGROUND: Up to 65% of untreated infants suffering from moderate to severe hypoxic-ischemic encephalopathy (HIE) are at risk of death or major disability. Therapeutic hypothermia (HT) reduces this risk to approximately 50% (number needed to treat: 7-9). Erythropoietin (Epo) is a neuroprotective treatment that is promising as an adjunctive therapy to decrease HIE-induced injury because Epo decreases apoptosis, inflammation, and oxidative injury and promotes glial cell survival and angiogenesis. We hypothesized that HT and concurrent Epo will be safe and effective, improve survival, and reduce moderate-severe cerebral palsy (CP) in a term nonhuman primate model of perinatal asphyxia. METHODOLOGY: Thirty-five Macaca nemestrina were delivered after 15-18 min of umbilical cord occlusion (UCO) and randomized to saline (n = 14), HT only (n = 9), or HT+Epo (n = 12). There were 12 unasphyxiated controls. Epo (3,500 U/kg × 1 dose followed by 3 doses of 2,500 U/kg, or Epo 1,000 U/kg/day × 4 doses) was given on days 1, 2, 3, and 7. Timed blood samples were collected to measure plasma Epo concentrations. Animals underwent MRI/MRS and diffusion tensor imaging (DTI) at <72 h of age and again at 9 months. A battery of weekly developmental assessments was performed. RESULTS: UCO resulted in death or moderate-severe CP in 43% of saline-, 44% of HT-, and 0% of HT+Epo-treated animals. Compared to non-UCO control animals, UCO animals exhibit poor weight gain, behavioral impairment, poor cerebellar growth, and abnormal brain DTI. Compared to UCO saline, UCO HT+Epo improved motor and cognitive responses, cerebellar growth, and DTI measures and produced a death/disability relative risk reduction of 0.911 (95% CI -0.429 to 0.994), an absolute risk reduction of 0.395 (95% CI 0.072-0.635), and a number needed to treat of 2 (95% CI 2-14). The effects of HT+Epo on DTI included an improved mode of anisotropy, fractional anisotropy, relative anisotropy, and volume ratio as compared to UCO saline-treated infants. No adverse drug reactions were noted in animals receiving Epo, and there were no hematology, liver, or kidney laboratory effects. CONCLUSIONS/SIGNIFICANCE: HT+Epo treatment improved outcomes in nonhuman primates exposed to UCO. Adjunctive use of Epo combined with HT may improve the outcomes of term human infants with HIE, and clinical trials are warranted.

Erythropoietin for neuroprotection in neonatal encephalopathy: safety and pharmacokinetics.

OBJECTIVE: To determine the safety and pharmacokinetics of erythropoietin (Epo) given in conjunction with hypothermia for hypoxic-ischemic encephalopathy (HIE). We hypothesized that high dose Epo would produce plasma concentrations that are neuroprotective in animal studies (ie, maximum concentration = 6000-10000 U/L; area under the curve = 117000-140000 U*h/L). METHODS: In this multicenter, open-label, dose-escalation, phase I study, we enrolled 24 newborns undergoing hypothermia for HIE. All patients had decreased consciousness and acidosis (pH < 7.00 or base deficit ≥ 12), 10-minute Apgar score ≤ 5, or ongoing resuscitation at 10 minutes. Patients received 1 of 4 Epo doses intravenously: 250 (N = 3), 500 (N = 6), 1000 (N = 7), or 2500 U/kg per dose (N = 8). We gave up to 6 doses every 48 hours starting at <24 hours of age and performed pharmacokinetic and safety analyses. RESULTS: Patients received mean 4.8 ± 1.2 Epo doses. Although Epo followed nonlinear pharmacokinetics, excessive accumulation did not occur during multiple dosing. At 500, 1000, and 2500 U/kg Epo, half-life was 7.2, 15.0, and 18.7 hours; maximum concentration was 7046, 13780, and 33316 U/L, and total Epo exposure (area under the curve) was 50306, 131054, and 328002 U*h/L, respectively. Drug clearance at a given dose was slower than reported in uncooled preterm infants. No deaths or serious adverse effects were seen. CONCLUSIONS: Epo 1000 U/kg per dose intravenously given in conjunction with hypothermia is well tolerated and produces plasma concentrations that are neuroprotective in animals. A large efficacy trial is needed to determine whether Epo add-on therapy further improves outcome in infants undergoing hypothermia for HIE.

Characteristics of rare disease marketing applications associated with FDA product approvals 2006-2010.

New drug and biologic product marketing applications submitted to FDA's Center for Drug Evaluation and Research (CDER) between 2006 and 2010 were analyzed to identify rare disease application characteristics associated with higher approval rates. The results show that approval rates were similar for rare and common disease applications. Larger company size, prior regulatory experience and priority review designation were associated with higher approval rates. The study findings show that rare disease product development is feasible, and increased interactions between product developers and FDA in early investigational phases can facilitate product development.

A phase I/II trial of high-dose erythropoietin in extremely low birth weight infants: pharmacokinetics and safety.

OBJECTIVES: High-dose recombinant erythropoietin is neuroprotective in animal models of neonatal brain injury. Extremely low birth weight infants are at high risk for brain injury and neurodevelopmental problems and might benefit from recombinant erythropoietin. We designed a phase I/II trial to test the safety and determine the pharmacokinetics of high-dose recombinant erythropoietin in extremely low birth weight infants. METHODS: In a prospective, dose-escalation, open-label trial, we compared 30 infants who were treated with high-dose recombinant erythropoietin with 30 concurrent control subjects. Eligible infants were <24 hours old,

Pharmacokinetics of high-dose recombinant erythropoietin in plasma and brain of neonatal rats.

Recombinant human erythropoietin (rEpo) is neuroprotective in neonatal models of brain injury. Pharmacokinetic data regarding the penetration of circulating rEpo into brain tissue is needed to optimize neuroprotective strategies. We sought to determine the pharmacokinetics of rEpo given intraperitoneally or subcutaneously in plasma and brain. We hypothesized that 1) exogenous rEpo would penetrate the blood-brain barrier (BBB), 2) brain and plasma Epo would correlate, and 3) brain injury would enhance rEpo penetration. Two hundred and eighty-four 7-d-old control, sham, or brain-injured rats were treated with i.p. or s.c. rEpo (0, 250, 2500, or 5000 U/kg) and killed at scheduled intervals. Plasma and brain tissue were collected. Epo concentrations were measured by ELISA. Intraperitoneal injection yielded a faster and greater peak concentration of plasma rEpo (Tmax 3 h, Cmax 10,016 +/- 685 mU/mL) than s.c. injection (Tmax 9 h, Cmax 6224 +/- 753 mU/mL). Endogenous brain Epo was below detection even after hypoxia exposure. Systemic rEpo crossed the BBB in a dose-dependent manner, peaked in brain at 10 h, and was increased after brain injury. We conclude that high-dose rEpo is detectable in brain for >20 h after a single systemic injection. These pharmacokinetic data are valuable for planning of rEpo neuroprotection experiments.

Levofloxacin and ciprofloxacin decrease procainamide and N-acetylprocainamide renal clearances.

Ten healthy adults participated in a randomized, crossover drug interaction study testing procainamide only, procainamide plus levofloxacin, and procainamide plus ciprofloxacin. During levofloxacin therapy, most procainamide and N-acetylprocainamide (NAPA) pharmacokinetic parameters, including decreased renal clearances and renal clearance/creatinine clearance ratios, changed (P < 0.05). During ciprofloxacin treatment, only procainamide and NAPA renal clearances decreased significantly.

Simulations of Levothyroxine Bioavailability Using a Single-Dose Study Protocol.

Computation of oral levothyroxine bioavailability parameters is hampered due to a long pharmacokinetic half-life and the secretion of endogenous levothyroxine hormone. To overcome these difficulties, Berg and Mayor (J Clin Pharmacol 1992; 32: 1135--1140) suggested the use of a single, supraphysiologic levothyroxine oral dosage protocol and measurement of levothyroxine area under the serum concentration versus time curves (AUC) for 48 h after dose administration. Since this protocol is a nonstandard methodology, simulations were performed to assess potential errors associated with the proposed method. The pharmacokinetic simulations indicate a potential methodological error of about 1% in AUC computations. However, for patients with extremely short levothyroxine half-lives (<2--3 days), larger errors in AUC values are possible.