bims-cyhorp Biomed News
on Cyclin-dependent kinases in hormone receptor positive breast cancer
Issue of 2022‒01‒02
two papers selected by
Piotr Okupski



  1. Clin Cancer Res. 2021 Dec 29. pii: clincanres.3032.2021. [Epub ahead of print]
      PURPOSE: Ribociclib plus endocrine therapy (ET) demonstrated a statistically significant progression-free survival and overall survival (OS) benefit in the phase 3 MONALEESA-7 trial of pre-/perimenopausal patients with hormone-receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer (ABC). The median OS was not reached in the ribociclib arm in the protocol-specified final analysis; we hence performed an exploratory OS and additional outcomes analysis with an extended follow-up (median, 53.5 months).PATIENTS AND METHODS: Patients were randomized to receive ET (goserelin plus nonsteroidal aromatase inhibitor [NSAI] or tamoxifen) with ribociclib or placebo. OS was evaluated with a stratified Cox proportional hazard model and summarized with Kaplan-Meier methods.
    RESULTS: The intent-to-treat population included 672 patients. Median OS was 58.7 months with ribociclib versus 48.0 months with placebo (HR, 0.76; 95% CI, 0.61-0.96). Kaplan-Meier estimated OS at 48 months was 60% and 50% with ribociclib and placebo, respectively. Subgroup analyses were generally consistent with the OS benefit, including patients who received NSAI and patients aged <40 years. Subsequent antineoplastic therapies following discontinuation were balanced between the ribociclib (77%) and placebo (78%) groups. Use of CDK4/6 inhibitors after discontinuation was higher with placebo (26%) versus ribociclib (13%). Time to first chemotherapy was significantly delayed with ribociclib versus placebo. No drug-drug interactions were observed between ribociclib and either NSAI.
    CONCLUSIONS: Ribociclib plus ET continued to show significantly longer OS than ET alone in pre-/perimenopausal patients, including patients aged <40 years, with HR+/HER2- ABC with 53.5 months of median follow-up. (ClinicalTrials.gov, NCT02278120).
    DOI:  https://doi.org/10.1158/1078-0432.CCR-21-3032
  2. Eur J Cancer. 2021 Dec 22. pii: S0959-8049(21)01245-4. [Epub ahead of print]162 45-55
      BACKGROUND: Inhibitors of the cyclin-dependent kinases 4 and 6 (CDK4/6i) have significantly improved clinical outcomes in patients with advanced hormone receptor-positive (HR+) breast cancer and have demonstrated favourable antitumour immune responses in preclinical studies.METHODS: Here, we investigated peripheral immune responses to ribociclib in patients with metastatic HR+ breast cancer as a preplanned exploratory subanalysis of the RIBECCA trial (NCT03096847). Peripheral blood mononuclear cells were subjected to immune cell profiling, gene expression analysis of immune-related signatures, and deep T cell receptor profiling before treatment started and after 12 weeks of treatment with ribociclib.
    RESULTS: Gene expression analysis revealed an upregulation of signatures associated with an activated adaptive immune system and a decrease in immunosuppressive cytokine signalling during treatment with ribociclib. Profiling of peripheral immune cell subpopulations showed a decrease in Treg cell frequencies, which was associated with treatment response. Furthermore, induction of CD4+ naive T cells could be seen, whereas effector and memory T cell populations remained largely unchanged. Correspondingly, T cell repertoire diversity remained mostly unchanged during treatment, although an increase in clonality could be observed in single patients.
    CONCLUSIONS: We show that treatment with ribociclib has significant effects on the peripheral innate and adaptive immune response in patients with HR+ breast cancer. Our data suggest that these effects lead to an activation of an already existing immune response rather than a de novo induction and make a strong case for future combination strategies of CDK4/6i with immunotherapies to enhance the adaptive immune response in HR+ breast cancer.
    Keywords:  Adaptive immunity; Breast cancer; CDK4/6 inhibitors; Immunomodulation; Ribociclib
    DOI:  https://doi.org/10.1016/j.ejca.2021.11.025