SAN DIEGO, Calif., June 1, 2026
Avenzo Therapeutics announced updated clinical results from the Phase 1 portion of its ongoing Phase 1/2 study evaluating AVZO-021, a potentially differentiated CDK2 selective inhibitor, in patients with advanced solid tumors. The data, presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, demonstrated encouraging clinical activity in heavily pretreated patients with HR-positive/HER2-negative breast cancer, while maintaining a favorable safety and tolerability profile. Across all monotherapy dose levels, median progression-free survival (PFS) reached 5.3 months in HR+/HER2- breast cancer patients who had received a median of four prior lines of metastatic therapy.
Updated Data Show Encouraging Clinical Activity and Disease Control
The study evaluated AVZO-021 both as a monotherapy and in combination with fulvestrant. Among efficacy-evaluable patients receiving monotherapy at doses of 150 mg daily and above, the disease control rate reached 85%, highlighting the potential of AVZO-021 in a patient population with limited treatment options after progression on prior therapies, including CDK4/6 inhibitors. Investigators reported four responses among patients receiving monotherapy and two confirmed responses in patients receiving the combination regimen. Notably, all responding patients remained on treatment, with several continuing therapy beyond 48 weeks.
Favorable Safety Profile Supports Combination Development Strategy
Updated safety findings showed AVZO-021 was generally well tolerated across dose levels. Most treatment-emergent adverse events were Grade 1 or Grade 2, with nausea, fatigue, anemia, and vomiting being the most commonly reported side effects. Importantly, the incidence and severity of gastrointestinal and hematologic toxicities appeared lower than those commonly associated with less selective CDK inhibitors. Pharmacokinetic analyses demonstrated continuous CDK2 target coverage at doses of 90 mg daily and above, while combination treatment with fulvestrant showed no meaningful drug-drug interactions.
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Avenzo Advances Next-Generation CDK Combination Approach
The updated results further support the ongoing development of AVZO-021 as a potential treatment option for patients with HR+/HER2- metastatic breast cancer, particularly in the setting of resistance following CDK4/6 inhibitor therapy. Avenzo is currently evaluating AVZO-021 alongside AVZO-023, its selective CDK4 inhibitor, in the ongoing ORION-1 Phase 1/2 study. The company believes the combination strategy could provide a differentiated approach to overcoming treatment resistance and improving outcomes for patients with advanced breast cancer.
Source: Avenzo Therapeutics press release
