Assessing a drug for an eradicated human disease: US Food and Drug Administration review of tecovirimat for the treatment of smallpox.

The development and ultimate approval of tecovirimat for the antiviral treatment of smallpox, a disease that has been eradicated from the world for nearly 40 years, required a unique regulatory approach based on the US Food and Drug Administration's Animal Rule. We summarise the regulatory pathway and describe the challenges involved.

How Often Are Drugs Made Available Under the Food and Drug Administration's Expanded Access Process Approved?

In this review of individual patient expanded-access requests to the Center for Drug Evaluation and Research for the period Fiscal Year 2010 to Fiscal Year 2014, we evaluated the number of applications received and the number allowed to proceed. We also evaluated whether drugs and certain biologics obtained under expanded access went on to be approved by the Food and Drug Administration. Finally, we considered concerns that adverse events occurring during expanded access might place sponsors at risk for legal liability. Overall, 98% of individual patient expanded-access requests were allowed to proceed. During the study period, among drugs without a previous approval for any indication or dosage form, 24% of unique drugs (ie, multiple applications for access to the same drug were considered to relate to 1 unique drug), and 20% of expanded-access applications received marketing approval by 1 year after initial submission; 43% and 33%, respectively, were approved by 5 years after initial submission. A search of 3 legal databases and a database of news articles did not appear to identify any product liability cases arising from the use of a product in expanded access. Our analyses seek to give physicians and patients a realistic perspective on the likelihood of a drug's approval as well as certain information regarding the product liability risks for commercial sponsors when providing expanded access to investigational drugs. The US Food and Drug Administration (FDA)'s expanded-access program maintains a careful balance between authorizing patient access to potentially beneficial drugs and protecting them from drugs that may have unknown risks. At the same time, the agency wishes to maintain the integrity of the clinical trials process, ultimately the best way to get safe and effective drugs to patients.

Clinical experience with intravenous zanamivir under an Emergency IND program in the United States (2011-2014).

BACKGROUND: Since the emergence of 2009 H1N1 virus, intravenous (IV) zanamivir has been authorized as an investigational treatment for patients with serious and life-threatening influenza through an Emergency Investigational New Drug application (EIND). This review encompasses the FDA's EIND database from May 2011 to June 2014. METHODS: This is a retrospective descriptive review of patient clinical data in the FDA's IV zanamivir EIND database from May 2011 to June 2014. RESULTS: Of 364 IV zanamivir EIND requests, most (83%) patients were aged 18-64 years, 8 (2%) were pregnant, and 29 (8%) were children. 234 (64%) patients had ≥1 comorbidity reported. The majority (87%) were receiving oseltamivir when IV zanamivir was requested, and 33% had suspected (n=120; no improvement or worsening on oseltamivir) H275Y oseltamivir resistance. Influenza A was reported for 300 patients: confirmed 2009 H1N1 (n=163), suspected 2009 H1N1 (n=8), confirmed H3N2 (n=4) and not subtyped (n=125). Influenza B was reported for 25 patients. Many patients (87%) required invasive mechanical ventilation, 23 (6%) received high frequency oscillatory ventilation, and 74 (20%) received extracorporeal membrane oxygenation (ECMO). 289 (79%) patients had ≥1 complication such as renal failure (n=124; 77/124 required dialysis), bacteraemia (n=18), shock (n=95) or pneumonia (n=159). Of 134 (37%) patients with available outcome data, 83 died and 51 survived. CONCLUSIONS: IV zanamivir EIND authorizations were for treatment of critically ill adult patients with 2009 H1N1, including a substantial number with suspected oseltamivir resistance. Data from prospective, randomized controlled trials are needed and are ongoing to assess the safety and efficacy of IV zanamivir for treatment of hospitalized patients with severe influenza.

Why did the FDA approve efavirenz 800 mg when co-administered with rifampin?

OBJECTIVES: Literature reports regarding the efficacy of efavirenz (EFV) 600 mg with rifampin (RIF) are not consistent. Evaluation of a drug-drug interaction (DDI) study and supportive semi-mechanistic population pharmacokinetic (PK) analyses were undertaken to help delineate this issue. DESIGN/METHODS: DDI study and supportive semi-mechanistic population PK analyses were provided by BMS. Population PK analysis was based on six studies with intensive EFV PK sampling. An ACTG study with sparse PK sampling was used for model evaluation. Simulations compared EFV exposure at various doses in combination with RIF to EFV exposures at 600 mg once daily (QD). Effects of CYP2B6 genotypes on the magnitude of EFV-RIF interaction were also explored. RESULTS: In DDI study, co-administering EFV 600 mg QD and RIF reduced mean EFV exposure by ~ 30%. Population PK model provided acceptable predictive performance of central tendency and variability for EFV C0, Cmax, and AUC. Simulations predicted that increasing EFV to 800 mg QD with RIF would result in EFV AUC and Cmax similar to EFV 600 mg QD alone. EFV AUC and Cmax were ~ 2 times higher in subjects with reduced function CYP2B6 genotypes. However, the RIF effect was consistent across all genotypes. EFV dose adjustment to 800 mg QD did not increase the risk of overexposure compared to 600 mg EFV QD within each genotype. CONCLUSION: Dose adjustment based on matching systemic exposure was recommended to mitigate the potential for sub-therapeutic EFV exposures. Our review did not reveal any safety concerns in subjects receiving EFV 800 mg QD with RIF.

Meta-analysis of gender differences in efficacy outcomes for HIV-positive subjects in randomized controlled clinical trials of antiretroviral therapy (2000-2008).

Women are often underrepresented in randomized clinical trials (RCT) of HIV-1 drugs. As a result, determining whether women have different virologic outcomes compared to men is not always possible because the gender-related analyses usually lack statistical power. To address this important public health concern, the Food and Drug Administration's (FDA) Division of Antiviral Products (DAVP) created a database including 20,328 HIV-positive subjects from 40 RCTs in 18 New Drug Applications (NDAs) submitted to the FDA between 2000 and 2008. These RCTs were conducted for at least 48 weeks in duration and were used to support approval of new molecular entity, new formulation, or major label change. To delineate potential gender differences in antiretroviral treatment (ART), we evaluated the percentage of subjects with HIV RNA less than 50 copies per milliliter at 48 weeks. Analyses of the database represent the most systematic review of gender-related ART efficacy data to date. Overall, the meta-analyses did not demonstrate statistically or clinically significant gender differences in virologic outcome at week 48. However, the corresponding subgroup analyses appear to show several statistically significant gender differences favoring males.

Original research: Intravenous ribavirin--review of the FDA's Emergency Investigational New Drug Database (1997-2008) and literature review.

Intravenous (IV) ribavirin does not have US Food and Drug Administration (FDA) approval, although oral and aerosol formulations have been approved. Intravenous ribavirin can, however, be authorized for use as a result of an Emergency Investigational New Drug (EIND) application as investigational treatment for patients with serious viral infections, including emerging or rare infections for which no alternative treatment is available. This retrospective study evaluated clinical experience with IV ribavirin based on a review of the FDA's EIND database and a literature review. The main outcome measures were disease condition, clinical outcomes, and adverse events (AEs). First, the FDA's EIND database was evaluated for these variables among patients authorized to receive investigational IV ribavirin. Second, published literature on IV ribavirin was reviewed for diseases treated, reported clinical outcomes, and AEs. Adverse events reported in the literature were compared with AEs listed in approved product labeling (aerosol and oral formulations). From February 1997 to December 2008, 608 IV ribavirin EIND requests were made for 19 disease conditions. Adenovirus, respiratory syncytial virus, and parainfluenza infections comprised 84.7% of IV ribavirin EINDs. Inadequate reporting of clinical outcomes and AEs in the EIND database prevented analysis of either outcome. Data interpretation in the literature was limited by multiple factors, including retrospective design, small sample sizes, differences in reporting outcomes and AEs, lack of generalizability, and potential confounders such as concomitant medications, selection bias, and reporting bias. Reported AEs were consistent with labels of approved aerosol and oral formulations, except for lip and gingival swelling. However, estimates of frequency, severity, and causality of AEs associated with IV ribavirin could not be determined because of study limitations. Our study findings suggest that the literature is inconclusive on the potential benefit for continued use of IV ribavirin. A review of the literature and the FDA's EIND database suggests that prospective, controlled trials of IV ribavirin in patients with adenovirus, parainfluenza, or serious respiratory syncytial virus infections could be feasible.

Risk factors for mortality from primary cryptococcosis in patients with HIV.

Cryptococcosis continues to have a high mortality rate in human immunodeficiency virus (HIV)-positive patients despite advances made in antifungal treatment, intracranial pressure management, and antiretroviral therapy. This retrospective chart review was conducted at the University of Maryland Medical Center and Baltimore VA Medical Center from 1993 to 2004. We reviewed all inpatient cases of cryptococcal infections to assess predictors of inpatient mortality among HIV-positive patients. Data collected included patient demographics, presenting symptoms and CD4 counts, lumbar puncture (LP) results including opening pressure (OP), cryptococcal antigen (CAg) levels, sites of infection, and drug therapy. Multivariate and survival analyses were performed. We identified 202 patients with primary cryptococcosis. The main sites of infection included blood (72%), central nervous system (85%), and lower respiratory tract (34%). Overall 30-day mortality was 14%. Predictors of mortality included syncope (P = 0.039; OR, 4.5), concomitant pneumonia (P = 0.001; OR, 3.5), respiratory failure (P < 0.001; OR, 10.5), and admission into the intensive care unit (P < 0.001; OR, 8). Amphotericin dose, OP > or = 250 mm H2O, and number of LPs were not found to be predictive of mortality. Mortality attributable to cryptococcosis remains high. Our study findings suggest that syncope, respiratory failure, pneumonia, and admission to the intensive care unit are independently associated with an increased risk of death within 30 days after cryptococcosis diagnosis.

Intracranial hemorrhage and liver-associated deaths associated with tipranavir/ritonavir: review of cases from the FDA's Adverse Event Reporting System.

Tipranavir (TPV), a protease inhibitor, has box warnings for intracranial hemorrhage (ICH) and hepatotoxicity (including hepatic failure and death). A box warning is a labeling statement about serious adverse events leading to significant injury and/or death. A box warning is the most serious warning placed in the labeling of a prescription medication. As a result of the respective morbidity and mortality associated with ICH and hepatic failure, the Food and Drug Administration's (FDA's) Adverse Event Reporting System (AERS) was searched for reports of these adverse events in HIV-infected patients receiving a tipranavir/ritonavir (TPV/r)-based regimen. This search comprised part of the FDA's safety analysis for traditional approval. From July 2006 to March 2007, 10 cases of ICH were identified in AERS. From June 2005 to March 2007, 12 cases of liver-associated deaths were identified. One patient experienced liver failure and fatal ICH. Most patients with these events had additional risk factors. Among patients with liver-associated deaths, 3 had HIV-RNA less than 400 copies per milliliter at the time of hepatic failure. Among 10 patients who discontinued TPV/r when hepatic failure developed, median number of days post-TPV/r to death was 23 (range, 2-69 days). Review of AERS did not identify new safety concerns regarding ICH. Among most patients with liver-associated deaths, death appears to occur soon after hepatic failure develops. If considering TPV/r, careful assessment of risk/benefit is suggested for patients at risk for ICH and hepatic failure.

Are literature references sufficient for dose recommendations? An FDA case study of efavirenz and rifampin.

One of the numerous regulatory functions of the Food and Drug Administration (FDA) is the evaluation of drug-drug interactions and the determination of appropriate dose adjustments, if necessary, to ensure the safe and effective use of medications. The FDA considers several data sources when determining the significance of drug-drug interactions. The majority of dose adjustment recommendations are based on specific drug-drug interactions studies. The FDA reviews individual patient pharmacokinetic and safety data from drug interaction studies, determines appropriate dose adjustments, and provides recommendations to update the respective product labeling. Sometimes literature references are submitted to the FDA to support dosing recommendations. Determining an appropriate dose adjustment recommendation based on literature reports is a challenge for the FDA due to the lack of individual patient pharmacokinetic or safety data from these studies. Recently, the FDA encountered a challenging regulatory situation when evaluating literature reports to determine the appropriate dose of efavirenz and rifampin. Although numerous studies were found in the literature about this combination, a dosing recommendation cannot be concluded from the reported data. This article reviews the process the FDA used to evaluate literature to support potential dose adjustments for efavirenz when coadministered with rifampin and the challenges encountered during the process.

Regulatory issues in developing new HIV protease inhibitors: risks and benefits.

PURPOSE OF REVIEW: To provide a regulatory perspective on developing new HIV protease inhibitors. The present review highlights the risks and benefits of certain design aspects for studies in treatment-naïve and treatment-experienced patients, including timing of studies, study design options, choice of control arms, and duration of treatment. RECENT FINDINGS: The present review highlights published studies to illustrate the need for new therapies and highlights potential historical data to help design future HIV clinical trials better. SUMMARY: New antiretroviral agents for patients with multidrug resistance, including safer, more convenient therapies without significant drug-drug interactions, are still needed for all patients. The goals of therapy have evolved and the expectation for treatment regimens is that the majority of patients, including treatment-experienced patients, will achieve undetectable HIV RNA. New study designs, particularly for treatment-experienced patients, are needed to help identify potential risks and benefits of new treatments.

Atazanavir-associated nephrolithiasis: cases from the US Food and Drug Administration's Adverse Event Reporting System.

The risk of nephrolithiasis associated with atazanavir is not well characterized. The US Food and Drug Administration's Adverse Event Reporting System was searched for reports of nephrolithiasis in HIV-infected patients taking an atazanavir-based regimen. Thirty cases were identified. Many patients required hospitalization for management, including lithotripsy, ureteral stent insertion, or endoscopic stone removal. Some cases of nephrolithiasis resulted in atazanavir discontinuation. Healthcare professionals and patients should be informed that nephrolithiasis is a possible adverse event with atazanavir.

Successful treatment with atazanavir and lopinavir/ritonavir combination therapy in protease inhibitor-susceptible and protease inhibitor-resistant HIV-infected patients.

The combination of atazanavir (ATV) plus lopinavir/ritonavir (LPV/r) has been used in practice. However, clinical data supporting its use are limited. The objective of this study was to evaluate the efficacy and tolerability of regimens with ATV + LPV/r in protease inhibitor (PI)-susceptible and PI-resistant patients. A retrospective review of 2703 charts was performed to identify all patients who received ATV + LPV/r. From June 2003 to January 2005, 33 patients received ATV + LPV/r with nucleoside reverse transcriptase inhibitors (NRTIs) for 3 months or more. Virologic success (HIV-RNA < 400 copies per milliliter) was achieved in 30 patients (91%) in a median of 10 weeks (range, 2-68). Nineteen of the 23 patients (83%) who had ultrasensitive viral load (VL) assays were nondetectable. Among patients with 6 or more protease resistance (PR) mutations (PI-resistant), 11 of 14 (79%) achieved virologic success. Eleven of those received phenotypic testing (10 Virtual Phenotype, VircoLab, Baltimore, MD). Despite predicted phenotypic resistance to ATV (6 patients) and LPV/r (7 patients), virologic success was achieved in 4 of 6 (67%) and 4 of 7 (57%), respectively. The 3 PI-resistant patients who were virologic failures had extensive prior LPV/r use, 8-11 PR mutations, and predicted phenotypic resistance to LPV/r, but 2 of 3 had CD4 increases with ATV + LPV/r. Overall, 28 patients (85%) continue to tolerate ATV + LPV/r for a median of 32 weeks follow-up (range, 12-76). Combination ATV + LPV/r with NRTIs appears safe, tolerable, and efficacious in PI-resistant patients (>/=6 PR mutations) and predicted phenotypic resistance to ATV and LPV/r. Further studies of ATV + LPV/r in HIV-treatment are warranted.

Acute renal failure and nephrotic range proteinuria due to amyloidosis in an HIV-infected patient.

Amyloidosis is an uncommon cause of renal disease in HIV-positive patients. Diagnosis is challenging, treatment options are limited, and prognosis remains poor. We discuss an HIV-positive patient with acute renal failure and nephrotic range proteinuria. The differential diagnosis included nephropathy due to trimethoprim/sulfamethoxazole, tenofovir, HIV, hepatitis C, heroin, or multifactorial causes. Serum and urine study findings were inconclusive. Rapid clinical deterioration ensued and a renal biopsy was performed. Pathologic examination revealed eosinophilic, amorphous material in the glomerular tufts that stained red-orange with Congo red stain. Immunohistochemical analysis confirmed amyloid A (AA) amyloidosis. AA amyloidosis occurs as a complication of chronic infection or chronic inflammatory disease. It has been reported in intravenous or subcutaneous drug abusers, some of whom were HIV-positive. This case underscores the importance of tissue diagnosis to determine the cause of renal disease in HIV-positive patients. Clinical diagnosis, based on CD4 count, viral load, and degree of proteinuria, may not predict the pathological diagnosis in HIV-positive patients.