Atossa Therapeutics, Inc. announced that the US Food and Drug Administration (FDA) issued a "Study May Proceed" letter for the company's study in metastatic breast cancer which was the subject of a recent Investigational New Drug Application (INDA) for (Z)-endoxifen.

"This letter marks an important regulatory milestone for Atossa and to potentially expand the use of (Z)-endoxifen for metastatic ER+/HER2- breast cancer. We believe its activity, even in tumours that have developed resistance to other endocrine therapies and in the oncogenic signaling pathway, protein kinase C beta 1 (PKCβ1), may offer a new tool in treating this disease. We appreciate the FDA's review and look forward to advancing this clinical investigation," said Dr Steven Quay, MD, PhD, President and Chief Executive Officer, Atossa Therapeutics.

(Z)-Endoxifen is a potent Selective Estrogen Receptor Modulator/Degrader (SERM/D) with demonstrated activity across multiple mechanisms of interest. Atossa is evaluating its potential applications in oncology and rare diseases. The company's proprietary oral formulation has shown a favourable safety profile and pharmacology distinct from tamoxifen, including ER-targeted effects and PKC inhibition. Atossa's (Z)-Endoxifen is not approved for any indication.

Atossa's (Z)-Endoxifen programme is supported by a growing global Intellectual Property (IP) portfolio, including multiple recently issued US patents and numerous pending applications worldwide.