FDA Denies Dynavax's Heplisav-B Expansion Due to Data Gaps

The FDA has declined to grant approval for Dynavax Technologies' request to expand the use of its hepatitis B vaccine, Heplisav-B, to adult patients undergoing haemodialysis. The decision was based on insufficient data, which stemmed from the destruction of trial records. This marks another obstacle for Heplisav-B, a vaccine that faced significant challenges before its initial approval. Previously, the FDA rejected the vaccine twice, in 2013 and 2016, due to unresolved safety concerns. It wasn't until 2017 that the vaccine was approved for preventing infections caused by all known subtypes of the hepatitis B virus in adults.

Dynavax is now seeking to broaden Heplisav-B's use to include a four-dose regimen for patients undergoing haemodialysis, an indication that received approval from EU regulators last October. However, in a complete response letter, the FDA stated that the application was inadequate. The primary issue was the destruction of data source documents for approximately half of the subjects enrolled in Dynavax's Phase I trial by a third-party site operator. The single-arm HBV-24 study assessed a four-dose Heplisav-B regimen in 119 adults on haemodialysis, revealing an immune protection rate of 89.3% against the hepatitis B virus. The FDA also noted that the total number of subjects was insufficient to properly evaluate the safety of the expanded dosing regimen.

Rob Janssen, Dynavax's chief medical officer, commented that all key data collected during the HBV-24 trial were verified against original source documents. He added that the company is reviewing the FDA's feedback and plans to request a meeting with the agency to explore options for providing additional data to support the four-dose regimen for this at-risk patient population.

The FDA's rejection does not affect Heplisav-B's current approved use for hepatitis B prevention in the United States. It also does not impact the recent European approval of the four-dose regimen for dialysis patients. Despite this setback, Dynavax remains optimistic about the vaccine's potential. The company reported that Heplisav-B generated approximately $48 million in revenue in the first quarter, representing a 10% increase year-over-year. CEO Ryan Spencer mentioned during the company's earnings call that there is a noticeable uptick in the market as healthcare providers shift focus to non-respiratory vaccine campaigns. Spencer emphasized the significant opportunity for the hepatitis B vaccine among the adult population in the U.S., where over 130 million patients are eligible for vaccination.

Dynavax continues to advocate for the expanded use of Heplisav-B, aiming to provide better protection for haemodialysis patients, a particularly vulnerable group. The company remains committed to working with the FDA to address the concerns raised and to find a path forward for the expanded use of the vaccine.