A phase Ib/II trial evaluating the angiogenesis inhibitor famitinib combined with the CDK4/6 inhibitor dalpiciclib and fulvestrant for HR+/HER2− advanced breast cancer was terminated early. Published on July 7, 2026, in the Chinese Medical Journal, the study led by Dr. Min Yan of Henan Cancer Hospital revealed that despite a promising objective response rate of 51.9%, high rates of adverse events and necessary dose reductions prevented the regimen from outperforming standard first-line therapies.
Trial Design and Efficacy Findings at Henan Cancer Hospital
HR+/HER2− breast cancer accounts for roughly 65% to 75% of all global breast cancer cases. While CDK4/6 inhibitors have noticeably extended progression-free survival, clinical data show that up to 60% of patients do not derive benefit from these medications.
The study enrolled 46 eligible patients. During the initial phase Ib dose-finding cohort of 18 patients, researchers established the recommended phase II dose as famitinib 10 mg daily combined with dalpiciclib 100 mg daily alongside fulvestrant. Moving into the phase II cohort of 28 patients, the confirmed objective response rate hit 51.9%, and the disease control rate reached 92.6%, successfully hitting the prespecified efficacy threshold for the first stage of analysis.
Toxicity Challenges and Progression-Free Survival Comparisons
Despite strong initial response rates, the median progression-free survival settled at 15.7 months. This figure failed to demonstrate an advantage over established standard first-line regimens. For context, alternatives like ribociclib paired with fulvestrant have yielded a median progression-free survival of 20.5 months in comparable patient populations.
“The ORR observed in our trial was numerically higher, but this did not translate into a longer PFS. This may be attributable to the high rate of dose reductions necessitated by adverse events, which likely compromised dose intensity and long-term efficacy,” stated Dr. Min Yan from the Department of Breast Disease at Henan Cancer Hospital.
Safety data showed that nearly all trial participants required dose reductions because of treatment-related adverse events. Grade 3 or higher toxicities were predominantly hematologic. Decreased neutrophil counts affected 96.4% of patients, decreased leukocyte counts impacted 75.0%, and decreased platelet counts were seen in 10.7%. Researchers noted that adding famitinib worsened hematologic toxicities past what either drug causes alone. They attribute this to a potential CYP3A4-mediated drug-drug interaction between famitinib and dalpiciclib.
Biomarker Analysis and Early Trial Termination
Investigators also conducted exploratory biomarker analyses during the trial. Results indicated no statistically significant outcome differences based on PIK3CA or BRCA1/2 mutation status. However, patients carrying these specific mutations experienced numerically shorter progression-free survival periods compared to wild-type groups.
Faced with these safety concerns and a lack of clear superiority over existing standard therapies, investigators terminated patient enrollment early following a thorough benefit-risk assessment. Commenting on future directions, Dr. Yan noted that while angiogenesis inhibitors may not serve as a preferred frontline choice for HR+/HER2− breast cancer, they might hold more promise for aggressive subtypes like triple-negative breast cancer or refractory disease.
Frequently Asked Questions About the Famitinib Trial
What was the primary goal of the clinical trial led by Dr. Min Yan?
The open-label phase Ib/II trial evaluated the safety and efficacy of adding the angiogenesis inhibitor famitinib to the CDK4/6 inhibitor dalpiciclib and fulvestrant for treating advanced HR+/HER2− breast cancer.
Why was the clinical trial terminated early?
Researchers ended enrollment early following a benefit-risk assessment that showed high rates of severe hematologic toxicities, frequent dose reductions, and a median progression-free survival of 15.7 months, which did not surpass standard first-line options.
What were the most common severe side effects reported?
The most frequent grade 3 or higher treatment-related adverse events were hematologic, including decreased neutrophil counts in 96.4% of patients, decreased leukocyte counts in 75.0%, and decreased platelet counts in 10.7%.
Did biomarker status affect patient outcomes in the study?
Exploratory biomarker analyses revealed no statistically significant differences in outcomes based on PIK3CA or BRCA1/2 mutation status, though patients with these mutations showed numerically shorter progression-free survival.
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