Qurient Announces First Patient Dosed in Phase 2 Trial of Novel CDK7 Inhibitor Mocaciclib (Q901) for the treatment of HR-Positive Breast Cancer

SEONGNAM, South Korea--(BUSINESS WIRE)--Qurient Co., Ltd. (KRX: 115180) today announced that the first patient has been dosed in a Phase 2 clinical study evaluating mocaciclib (Q901) in combination with fulvestrant for treatment of hormone receptor-positive (HR+) breast cancer. The trial specifically targets patients who have stopped responding to prior treatments containing CDK4/6 inhibitors. Mocaciclib is a highly selective and potent covalent inhibitor of cyclin-dependent kinase 7 (CDK7), developed to address significant unmet medical needs in advanced solid tumors, including treatment-resistant breast cancer.

The dosing of the first patient with CDK4/6 inhibitor-resistant HR+ breast cancer marks a significant milestone in development of mocaciclib as a new therapeutic option. While CDK4/6 inhibitors combined with endocrine therapy have proven highly effective for treatment of HR-positive, HER2-negative metastatic breast cancer, many patients eventually experience disease progression due to innate non-responsiveness or acquired resistance. Mocaciclib is being investigated as a targeted solution to overcome the refractory conditions through cell cycle control and transcriptional regulation of key refractory mechanisms, such as PTEN-PI3K/AKT pathway activation.

"Dosing the first HR-positive breast cancer patient with mocaciclib is an important step forward in our mission to provide new therapeutic options for patients who have exhausted standard-of-care treatments," said Kiyean Nam, Ph.D., Chief Executive Officer of Qurient. "Because of its unique mechanism of action in cell cycle control and transcriptional regulation, mocaciclib holds promise for patients whose tumors have developed bypass mechanisms to evade CDK4/6 inhibition. We are highly encouraged by our latest findings in CDK7 biology and look forward to translating this science into meaningful clinical outcomes."

Mechanism of Action Rationale in HR+ Breast Cancer

Mocaciclib (Q901) provides a novel therapeutic strategy for HR+ breast cancer by targeting CDK7, a dual-function kinase essential for both cell cycle progression and transcriptional regulation:

• Master Regulation of the Cell Cycle (CAK Inhibition): CDK7 acts as the CDK-activating kinase (CAK), responsible for phosphorylating the T-loop of other key cell cycle kinases, including CDK1, CDK2, CDK4, and CDK6. In HR+ breast cancer, resistance to CDK4/6 inhibitors frequently occurs through the loss of retinoblastoma (RB) protein function or the over-activation of the Cyclin E-CDK2 axis. This allows cancer cells to bypass the CDK4/6 blockade and re-enter the S-phase of division. By potently inhibiting CDK7, mocaciclib suppresses the activation of CDK2 and other downstream kinases, effectively shutting down these alternative escape routes and halting tumor proliferation.

• Targeted Transcriptional Repression: Beyond cell cycle control, CDK7 is a core component of the transcription factor II H (TFIIH) complex. Mocaciclib selectively disrupts the transcription of heavily relied-upon oncogenic transcription factors (such as MYC and E2F) and suppresses the expression of genes that are activated by the PTEN-PI3K/AKT pathway, effectively neutralizing another mechanism of CDK4/6 inhibitor resistance.

About Mocaciclib (Q901)

Mocaciclib (Q901) is an intravenously administered, highly selective covalent CDK7 inhibitor currently advancing through Phase 1/2 clinical trials (NCT05394103). In addition to its potential as a monotherapy in HR+ breast cancer and other advanced solid tumors, mocaciclib has demonstrated profound synergy in preclinical models when used in combination with Topoisomerase 1 inhibitor-based antibody-drug conjugates (TOP1i-ADCs) and immune checkpoint inhibitors.

About Qurient

Qurient Co., Ltd. is a clinical-stage biopharmaceutical company focused on the discovery and development of novel therapeutics for oncology and inflammatory diseases. Utilizing a network-centric research and development model, Qurient successfully collaborates with top-tier research institutes and global pharmaceutical companies to translate innovative science into impactful medicines.

Website: www.qurient.com

Note: This press release contains forward-looking statements regarding the clinical potential of mocaciclib (Q901). These statements are based on current expectations and assumptions and are subject to risks and uncertainties that could cause actual results to differ materially.