Clinical-stage biopharmaceutical company Atossa Therapeutics Inc (Nasdaq:ATOS) announced on Wednesday that it has been granted US Patent No. 12,281,056, expanding protection for its (Z)-endoxifen portfolio with 58 claims covering oral formulations and therapeutic uses.

The patent strengthens Atossa's intellectual property around highly pure and stable enteric oral formulations of (Z)-endoxifen, a potent Selective Estrogen Receptor Modulator.

This newly granted patent adds to the company's broad US patent estate, which includes more than 200 claims related to (Z)-endoxifen formulations and clinical applications.

Atossa is focused on advancing proprietary therapies targeting hormone receptor-positive breast cancer, where (Z)-endoxifen has demonstrated potential even in treatment-resistant tumors.

(Z)-endoxifen is designed to avoid stomach acid degradation by using encapsulated oral delivery, preserving efficacy compared to the inactive (E)-endoxifen form. The compound also shows potential to inhibit estrogen receptors, degrade oncogenic proteins like PKCβ1, and maintain favorable safety and bone health profiles versus traditional therapies.

Clinical studies have shown (Z)-endoxifen is well tolerated in women with and without breast cancer.

Atossa is studying the drug for both prevention and treatment, including metastatic breast cancer.