On June 1, 2026 Avenzo Therapeutics, Inc. ("Avenzo"), a clinical-stage biotechnology company developing next-generation oncology therapies, 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.
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The findings were reported at the 2026 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) 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."
(Press release, Avenzo Therapeutics, JUN 1, 2026, View Source [SID1234666299])