Examining Tenofovir Alafenamide Versus Tenofovir Disoproxil Fumarate in the Treatment of HBV

Tenofovir alafenamide is an antiviral medication used to treat a hepatitis B virus (HBV) infection and was approved by the FDA in 2015. The therapy has demonstrated a decreased incidence of bone loss and renal decline compared to tenofovir disoproxil fumarate, which has been used to treat HBV since 2004.

Two studies looked deeper into the subject of tenofovir alafenamide versus tenofovir disoproxil fumarate. The data was presented at the American Society of Health-System Pharmacists 2023 Midyear Clinical Meeting and Exhibition.

For the first study, investigators from the UC Irvine Medical Center conducted a single center, retrospective study to assess the effects of switching from tenofovir disoproxil fumarate to tenofovir alafenamide over a 4 year period.¹ The study included 53 patients with chronic HBV with a mean age of 55, of which 45.3% were males.

At the beginning of the study, mean baseline alanine aminotransferase was 24.8 IU/L, aspartate aminotransferase was 25.7 IU/L, aspartate aminotransferase to platelet ratio index was 0.37, Fibrosis-4 scores were 1.66, and serum creatine was 0.85 mg/dL. Investigators found that after switching to tenofovir alafenamide, mean ranges of alanine aminotransferase, aspartate aminotransferase, aspartate aminotransferase to platelet ratio index, and Fibrosis-4 scores were improved persistently.

“Our data demonstrated that switching from tenofovir disoproxil fumarate to tenofovir alafenamide for 4 years results in not only persistent and durable alanine aminotransferase and aspartate aminotransferase improvement, but also hepatic fibrosis improvement by aspartate aminotransferase to platelet ratio index and FIB-4 scores through mean reduction and great improvement rates,” the authors concluded. “The renal function was stable and also improved.”

For the second study, investigators from Emory University Hospital in Georgia evaluated the impact of clinical and specialty pharmacy services in transitioning patients from tenofovir disoproxil fumarate to tenofovir alafenamide.² Data was gathered from before clinical pharmacy services were implemented (11/10/16 to 8/31/18) and after (9/1/18 to 2/28/21).

The primary study endpoint was the rate of transition from tenofovir disoproxil fumarate to tenofovir alafenamide. Secondary endpoints included creatinine clearance changes from baseline to 6-12 months after switching, percent of patients receiving copay assistance, and bone loss.

The study cohort included 191 patients who had chronic hepatitis B, were prescribed an HBV medication, and were actively followed by Emory Hepatology. Investigators found that 18.8% of patients were transferred before the implementation of services, while 60% were transferred after.

Out of the patients who filed at Emory, 71% needed copay assistance. Creatinine clearance was found to improve 8% to 14% from baseline at 6-12 months after switching medications. Additionally, dexascan demonstrated osteoporosis or osteopenia in 8.9% of patients.

“The rate of patients transitioned from tenofovir disoproxil fumarate to tenofovir alafenamide more than doubled after clinical pharmacist services and health system specialty pharmacy resources were utilized,” the authors concluded. “A significant portion of patients utilized copay assistance resources necessitating assessment of affordability and access prior to transition. Copay assistance for those filling outside Emory could not be assessed. Small renal function improvements were noted in patients transitioning from tenofovir disoproxil fumarate to tenofovir alafenamide.”

References

1. Huynh T, Bui DM, Hu K. Benefits of Switching Tenofovir Disoproxil Fumarate to Tenofovir Alafenamide up to Four Years in Patients with Chronic Hepatitis B. Presented at: American Society of Health-System Pharmacists Midyear Clinical Meeting & Exhibition; December 3-7, 2023; Anaheim, CA. Poster 8-029.

2. Fuller KG, Sun L, Cox A, et al. Impact of Clinical and Specialty Pharmacy Services on Hepatitis B Virus Treatment Optimization. Presented at: American Society of Health-System Pharmacists Midyear Clinical Meeting & Exhibition; December 3-7, 2023; Anaheim, CA. Poster 4-006.