Protagonist Therapeutics (PTGX.Q) announced the receipt of verbal communication from the U.S. Food and Drug Administration (FDA) that the Company’s clinical studies for rusfertide have been placed on a clinical hold.
“Patient safety is our absolute top priority…We are fully committed to working closely with the FDA in understanding and evaluating potential clinical risks and determining next steps for the development of rusfertide,” said Dinesh Patel, President and Chief Executive Officer of Protagonist.
So, why did Protagonist’s shares plummet 60% today? Before we get into it, let’s talk about the Company for a second. Protagonist is a biopharmaceutical company with multiple peptide-based investigational new chemical entities in different stages of development, derived from the Company’s proprietary technology platform. Included in Protagonist’s pipeline of products is rusfertide (PTG-300), which was previously being investigated in a Phase 2 clinical trial for polycythemia vera (PV) and a Phase 2 study for hereditary hemochromatosis. This is where things get interesting. For context, PV is a type of blood cancer that causes bone marrow to make too many blood cells. The overproduction of red blood cells can thicken blood, potentially leading to serious problems such as blood clots. Here’s the kicker.
The clinical hold follows Protagonist’s notification to the FDA of a recent non-clinical finding in a 26-week rasH2 transgenic mouse model study. The rasH2 model is designed to detect signals related to tumorigenicity, and benign and malignant subcutaneous skin tumors were observed in this study. Yikes. As previously mentioned, there were a couple of Phase 2 clinical trials utilizing rusfertide being conducted prior to the Company’s latest press release. With this in mind, following Protagonist’s clinical hold, the dosing of patients in all ongoing clinical trials with rusfertide will be put on hold. Additionally, the Company is working with the FDA and will be prepared to make all the appropriate updates to clinical study documents and determine the next steps in consultation with the FDA. Furthermore, Protagonist will provide additional clinical safety reports, update the investigator brochures and patient informed consent forms, and make necessary modifications to study protocols.
Protagonist’s share price opened at $20.44, down from a previous close of $46.13. The Company’s shares are down 63% and are currently trading at $16.73 as of 12:01 PM ET.