# Safety of up to 140 Daily Applications of Recombinant Human Platelet‐Derived Growth Factor (rhPDGF‐BB) Onto Skin Wounds: Unboxing the Evidence

## TL;DR

This paper examines the safety of using a growth factor gel on skin wounds and confirms it is safe even with frequent use.

## Contribution

The paper provides robust evidence leading to the removal of a cancer risk warning from a FDA-approved wound healing product.

## Key findings

- Up to 140 daily applications of rhPDGF-BB onto skin wounds are safe with no increased cancer risk.
- Large-scale studies with over 13,000 patients confirmed the safety of frequent use of Regranex gel.
- The removal of a boxed warning on the product label was achieved through extensive and robust evidence.

## Abstract

Recombinant human platelet‐derived growth factor BB (rhPDGF‐BB), is the only growth factor approved by the US Food and Drug Administration (FDA) for tissue regeneration and rejuvenation indications. It has received four FDA approvals for both soft tissue (e.g., skin) and hard tissue regeneration/rejuvenation. Regranex gel, 0.01% rhPDGF‐BB, is the only growth factor approved by the FDA for the promotion of skin wound healing. While the safety of one and two 15 g tubes of Regranex, generally sufficient for up to 60 daily applications onto open skin wounds, has never been questioned, a decade after its introduction in 1997, a boxed warning regarding rates of cancer mortality was placed on its label for daily use of three or more tubes. This was based on a mathematical calculation on incomplete data from an insurance claims database which was subsequently invalidated with the addition of three more years of data. Removal of this warning from the label required another decade and several very large propensity‐matched database studies including over 13,000 patients. These studies provided incontrovertible proof that up to 140 daily applications (≥ 4 tubes) of rhPDGF‐BB onto open skin wounds are safe, with no increased risk of either cancer development or cancer mortality. Removing a boxed warning is an arduous task that requires extensive and robust evidence; less than 4% of box warnings are removed once placed. Thus, the successful removal of the boxed warning from the Regranex label should reassure both prescribers and patients of the product's safety.