Samuraciclib Shows PFS Benefit in Biomarker-Selected HR+ Breast Cancer
Samuraciclib improved progression-free survival in HR+ advanced breast cancer patients without TP53 mutations or liver metastases.
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When given to patients with hormone receptor-positive (HR+) advanced breast cancer who had received prior CDK4/6 inhibitor therapy, samuraciclib (CT7001) improved progression-free survival (PFS), both in patients with no TP53 mutation, compared with those with a mutation, and in patients without liver metastases, compared with those with liver metastases, according to an analysis of 2 phase 2 clinical trials presented at 2025 European Society for Medical Oncology (ESMO) Breast Cancer Annual Congress.1
The first trial, MORPHEUS (NCT03280563), evaluated samuraciclib plus giredestrant (n = 15), and the Module 2A trial evaluated samuraciclib in combination with fulvestrant (n = 31). In the MORPHEUS trial, patients with no TP53 mutation had a PFS of 14.2 vs 1.8 months for patients with a TP53 mutation. The PFS rates for patients with and without liver metastases were 1.8 and 14.2 months, respectively.
In Module 2A, PFS for patients with and without TP53 mutations were 1.8 and 7.4 months, respectively, and for patients with and without liver metastases, these rates were 2.8 and 13.8 months.
"Based on the results from these 2 independent studies, we have identified patient populations showing improved progression-free survival, highlighting the potential of samuraciclib in combination with [selective estrogen receptor degraders (SERDs)] as an effective new treatment option for these patients. Carrick is further validating these 2 selection strategies in 2 additional phase 2 studies reading out later this year with the intent to advance to phase 3 in 2026, enriching 1 of these 2 patient groups,” said Tim Pearson, chief executive officer of Carrick Therapeutics, in a press release.
These data further support the biomarker-driven patient selection strategy used by Carrick Therapeutics.
“Patients with HR-positive, HER2-negative [HER2–] advanced breast cancer are typically treated with a CDK4/6 inhibitor in combination with an endocrine therapy, but unfortunately almost all patients eventually develop resistance to therapy,” said Stuart McIntosh, MD, chief medical officer of Carrick Therapeutics, in the press release. “Those patients are in need of effective new targeted therapies that are durable and tolerable in combination with endocrine therapy, including oral SERDs. These results from 2 independent trials of samuraciclib in combination with a SERD are very encouraging.”
The drug developer, Carrick Therapeutics, is further refining its patient-selection approach through 2 ongoing phase 2 trials. In partnership with the Menarini Group, the company is conducting the SUMIT-ELA trial (NCT05963997), which assesses the safety and efficacy of samuraciclib combined with the oral SERD elacestrant (Orserdu) in patients with HR+, HER2– locally advanced or metastatic breast cancer who have previously been treated with a CDK4/6 inhibitor and aromatase therapy. Additionally, the randomized SUMIT-BC trial (NCT05963984) is comparing samuraciclib plus fulvestrant vs fulvestrant alone in a similar patient population.
Through these global, multicenter SUMIT studies, Carrick will evaluate CDK7 inhibitor and SERD combination therapy in more than 150 patients.
About Samuraciclib
Samuraciclib is a novel, investigational, first-in-class inhibitor of CDK7. The oral agent is in clinical development and has demonstrated a favorable safety profile and encouraging efficacy in early clinical studies in HR-positive breast cancer.
Samuraciclib also has the potential to treat prostate, pancreatic, small cell lung, triple negative breast, ovarian, and colorectal cancers due to its ability to inhibit CDK7. Already, samuraciclib has been granted FDA fast track designation for its use in combination with fulvestrant for the treatment of patients with CDK4/6i resistant HR+, HER2– advanced breast cancer.
