Amid Ethics Allegations, Sesen Pulls Bladder Cancer Drug Application from Europe
Less than 10 days after the U.S. Food and Drug Administration (FDA) slammed Sesen Bio’s bladder cancer drug with a Complete Response Letter, the company has withdrawn its Marketing Application Authorization from the European Union.
In a filing with the U.S. Securities and Exchange Commission, Sesen Bio said its decision to pull the MAA was based on the FDA’s CRL. The company acknowledged that certain components in the European Medicines Agency review are “interrelated” with some of the elements that forced the FDA to issues the CRL for Viceneum (oportuzumab monatox-qqrs) as a treatment for BCG-unresponsive non-muscle invasive bladder cancer (NMIBC). Sesen is pausing its plans to pursue approval in Europe until there is more clarity from the FDA on the next steps it must take to win approval.
The company has also requested a Type A meeting with the FDA to discuss those necessary steps. Additionally, Sesen made a curious comment that noted it is “committed to the highest standards of ethics and integrity and continues to believe in the safety and efficacy data of Vicineum.”
That comment points back to a STAT News report alleging that Sesen’s entire clinical program for Viceneum was allegedly marked by multiple instances of unethical behavior. According to the report, the company’s clinical program saw “thousands of violations of study rules” and “damning investigator misconduct.” It also added that Sesen’s drug had much poorer safety data than was reported.
The news also revealed that the company did not disclose “worrying signs of toxicity” and that it was backed by hundreds of pages of internal documents from Sesen, as well as confirmation by “three people familiar with the matter.” Sesen has yet to comment against the allegations raised by the report.
Vicenium, the drug Sesen is hoping to gain approval for, is a recombinant fusion protein. Vicenium targets epithelial cell adhesion molecule (EpCAM) antigens located on the surface of tumor cells. It aims to deliver what has been described as a potent protein payload of Pseudomonas Exotoxin A to the tumor.
When the FDA rejected Vicenium, the regulatory agency recommended that Sesen conduct additional clinical and statistical data analyses. The FDA also recommended addressing issues related to the company’s Chemistry, Manufacturing, and Controls (CMC). In the CRL, the FDA expressed concern about drug substance and drug product manufacturing, cell bank, characterization, resin reuse, reference standards, methods, specifications, stability, and microbiology.
Shares of Sesen Bio are down nearly 2% in premarket trading to $1.05, losing the gains it made on Wednesday. Since the CRL was issued, Sesen’s stock has fallen from a 2021 high of $4.91 per share.