Avenzo Therapeutics Presents Updated Results from the Phase 1/2 Study of AVZO-021, a Potentially Differentiated CDK2 Inhibitor, at the 2026 American Society of Clinical Oncology Annual Meeting

SAN DIEGO, Calif. – June 1, 2026 – Avenzo Therapeutics, Inc. (“Avenzo”), a clinical-stage biotechnology company developing next-generation oncology therapies, today reported updated clinical data from the Phase 1 portion of its ongoing Phase 1/2 clinical study of AVZO-021, its potentially differentiated cyclin-dependent kinase 2 (CDK2) selective inhibitor. The updated data demonstrated clinical activity in heavily pretreated patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) breast cancer. Across all monotherapy doses, median progression-free survival (PFS) for all HR+/HER2- breast cancer patients, with a median of 4.0 (min, max: 1, 9) prior lines of therapies in the metastatic setting, was 5.3 months. Consistent with previously reported findings, AVZO-021 was generally well tolerated with relatively low incidence and severity of gastrointestinal and hematologic adverse events, which are commonly observed adverse events associated with less selective CDK inhibitors.

The findings were reported at the 2026 American Society of Clinical Oncology Annual Meeting.

“HR+/HER2- breast cancer progression following CDK4/6 inhibitors represents a significant area of unmet need, with limited treatment options,” said Manish R. Patel, M.D., Director of Drug Development, Florida Cancer Specialists/Sarah Cannon Research Institute. “CDK2 is increasingly recognized as a key driver of resistance in this setting. The updated data presented today for AVZO-021 continue to demonstrate encouraging clinical activity and favorable tolerability, further supporting its potential in combination treatment strategies, including with AVZO-023, Avenzo’s potentially differentiated CDK4 inhibitor.”

AVZO-021, Phase 1 Updated Clinical Data

Utilizing a March 30, 2026 data cut-off date, 51 patients with advanced solid tumors were treated with AVZO-021 monotherapy, and 13 patients with HR+/HER2- breast cancer were treated with AVZO-021 in combination with fulvestrant.

Among all 51 patients, the median number of prior therapies in the metastatic setting was 3.0 (min, max: 0, 11), with all 33 patients with HR+/HER2- breast cancer having received at least one prior CDK4/6 inhibitor and 8 (24.2%) having received at least two prior CDK4/6 inhibitors in the metastatic setting.

Utilizing a May 7, 2026 data cut-off date for efficacy, 39 patients were efficacy-evaluable including 26 patients with HR+/HER2- breast cancer or CCNE1-amplified solid tumors treated with AVZO-021 monotherapy doses of 150 mg once daily (QD) and above with at least one evaluable post-baseline scan, and 13 patients with HR+/HER2- breast cancer treated with AVZO-021 in combination with fulvestrant with at least one evaluable post-baseline scan.

Updated Safety Results

A total of 64 patients comprise the safety population, including 51 patients with advanced solid tumors treated with AVZO-021 monotherapy at dose levels from 20 mg QD to 250 mg QD, and 13 patients with HR+/HER2- breast cancer treated with AVZO-021 in combination with fulvestrant at AVZO-021 dose levels of 150 mg QD and 200 mg QD.
All-grade treatment emergent adverse events (TEAEs) reported in greater than 20 percent of patients were nausea (52%), fatigue (48%), anemia (39%), and vomiting (34%).
The majority of TEAEs were Grade 1 or Grade 2.

Updated Pharmacokinetic and Pharmacodynamic Results

PK data suggested continuous CDK2 target coverage was achieved at doses of 90 mg QD and above.
Comparable exposures of AVZO-021 were observed between AVZO-021 monotherapy and in combination with fulvestrant at 150 mg QD and 200 mg QD, indicating no drug-drug interaction.
No food effects were observed in the pilot food effect substudy.
Decreases in circulating tumor DNA (ctDNA) were observed.

Updated Efficacy Results

Across all monotherapy doses, median PFS for all HR+/HER2- breast cancer patients (n=33), with a median of 4.0 (min, max: 1, 9) prior therapies, was 5.3 months (95% CI: 1.9, 7.2) with median follow-up time of 8.4 months.
The disease control rate for HR+/HER2- breast cancer efficacy-evaluable patients treated with 150 mg QD and above monotherapy (n=20) was 85% (95% CI: 62.1, 96.8).
Of 26 efficacy-evaluable patients treated with AVZO-021 monotherapy, four patients had a response (three with confirmed responses, and one with an unconfirmed response who remained on treatment awaiting a confirmatory scan) at the time of the data cut-off.
Of 13 efficacy-evaluable patients with HR+/HER2- breast cancer treated with AVZO-021 in combination with fulvestrant, two patients had confirmed responses.
All responders remained on treatment, including three patients on treatment for greater than 48 weeks.

“We are encouraged by the updated clinical data for AVZO-021, which continue to show clinical activity along with tolerability that we believe support combination strategies in HR+/HER2- breast cancer,” said Mohammad Hirmand, M.D., Co-founder and Chief Medical Officer of Avenzo Therapeutics. “As we strive towards our goal of delivering novel and meaningful treatment options to patients, we are excited to be evaluating the combination of AVZO-021 and AVZO-023, our potentially differentiated CDK4 selective inhibitor, with fulvestrant in patients with HR+/HER2- breast cancer in the ongoing Phase 1 portion of the ORION-1 Phase 1/2 clinical study.”

About Avenzo Therapeutics
Avenzo Therapeutics is a clinical-stage biotechnology company focused on developing next-generation oncology therapies for patients. The company’s pipeline includes potentially differentiated small molecules and antibody-drug conjugates (ADCs). Avenzo’s small molecule inhibitors, AVZO-021 and AVZO-023, are novel, highly potent and selective inhibitors of CDK2 and CDK4, respectively, which are key enzymes involved in cell cycle regulation. AVZO-021 is being studied in a Phase 1/2 study for the treatment of advanced solid tumors and in combinations in HR+/HER2- metastatic breast cancer. AVZO-021 and AVZO-023 are being studied in the ORION-1 Phase 1/2 study for the treatment of HR+/HER2- metastatic breast cancer, where AVZO-023 is administered in combination with endocrine therapy, with or without AVZO-021. Avenzo’s first ADC drug candidate, AVZO-1418, is a potentially differentiated EGFR/HER3 bispecific ADC that is being studied in the AVENTINE-1 Phase 1/2 study for the treatment of advanced solid tumors. Avenzo’s second ADC drug candidate, AVZO-103, is a potentially differentiated Nectin4/TROP2 bispecific ADC that is being studied in the BEACON-1 Phase 1/2 study for the treatment of advanced solid tumors. Avenzo is headquartered in San Diego, California. For more information, visit us at www.avenzotx.com or on LinkedIn.

Forward-Looking Statements
This press release contains forward-looking statements as that term is defined in the Private Securities Litigation Reform Act of 1995, including, without limitation, statements regarding: the therapeutic potential and potential benefits of Avenzo’s product candidates, including AVZO-021, and the potential of AVZO-021 in combination treatment strategies, including with AVZO-023. These statements are subject to a number of risks, uncertainties and assumptions, including, but not limited to: preliminary and interim clinical results may not be indicative of results that may be observed in later stages of development or in larger patient populations; the timing and success of clinical trials and potential safety and other complications thereof; the uncertainties associated with the clinical development and regulatory approval of product candidates, including potential delays in the commencement, enrollment and completion of clinical trials; uncertainties in obtaining successful clinical results for product candidates and unexpected costs that may result therefrom; risks related to the failure to realize any value from product candidates and preclinical programs being developed and anticipated to be developed; and risks related to the inability of Avenzo to obtain sufficient additional capital to continue to advance its product candidates and its preclinical programs. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties. You should not place undue reliance on these forward-looking statements, which are made only as of the date hereof or as of the dates indicated in the forward-looking statements. Avenzo expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in its expectations with regard thereto or any change in events, conditions or circumstances on which any such statements are based.

Avenzo Therapeutics Contact:
Carla Taub
Media Relations
ctaub@avenzotx.com