Abstract P6-18-06: Ribociclib treatment benefit in patients with advanced breast cancer with ≥1 dose reduction: Data from the MONALEESA-2, -3, and -7 trials

Justifying Ribociclib Dose in Patients with Advanced Breast Cancer with Renal Impairment Based on PK, Safety, and Efficacy Data: An Innovative Approach Integrating Data from a Dedicated Renal Impairment Study and Oncology Clinical Trials

BACKGROUND AND OBJECTIVE

Renal impairment is common in patients with cancer and can alter the PK and thus the safety and efficacy of drugs. We assessed the impact of renal impairment during treatment with ribociclib, a cyclin-dependent kinase 4/6 inhibitor, and determined dose recommendations for patients with advanced breast cancer with renal impairment.

METHODS

A comprehensive assessment integrating pharmacokinetic, safety, and efficacy data from a phase I dedicated renal impairment study in non-cancer subjects and six phase I-III trials in patients with cancer was performed.

RESULTS

Ribociclib showed higher pharmacokinetic exposure in subjects with renal impairment than those with normal renal function following a single 400-mg dose in the dedicated renal impairment study. However, in patient trials, both single-dose and steady‑state ribociclib exposure was comparable between patients with cancer with mild/moderate renal impairment and those with normal renal function following the recommended starting dose of 600 mg. Model-predicted steady‑state exposure in patients with advanced breast cancer was also similar across the renal function groups. Progression-free survival was similar and safety profiles were generally consistent across the renal cohorts (normal/mild/moderate) in patients with advanced breast cancer, with low-grade and manageable adverse events, demonstrating a positive benefit-risk profile.

CONCLUSIONS

From the collective evidence and considering a real-world clinical setting, no dose adjustment is recommended for patients with mild/moderate renal impairment, whereas a reduced dose is recommended for patients with severe renal impairment. This report presented a holistic and innovative strategy to determine dose in patients with renal impairment and demonstrated the effectiveness of integrating the data of both a clinical pharmacology study and patient trials to justify doses in patients with renal impairment.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov identifiers: NCT02431481, NCT01958021, NCT02422615, NCT02278120, NCT01237236, NCT01898845, NCT01872260.

Dose modifications of ribociclib and endocrine therapy for treatment of ER+ HER2- metastatic breast cancer

PURPOSE

Treatment for estrogen receptor positive (ER+), human epidermal receptor 2 negative (HER2-) metastatic breast cancer (MBC) has improved with the approval of CDK 4/6 inhibitors. Clinical trials with the CDK4/6 inhibitor ribociclib, suggest that 35% to 57.5% of the patients require a dose reduction during ribociclib treatment. Data on the possible consequences of dose reduction concerning efficacy is needed.

METHODS

A retrospective cohort study on patients with ER+ HER2- MBC from three Danish oncology departments. Data on tolerability and progression-free survival were collected from electronic health records.

RESULTS

One hundred and twenty-eight patients with ER+ HER2- MBC who initiated ribociclib treatment between 1st of January 2018 to 31st of March 2020 were included in our analysis. Of these patients, 48.4% required one or more dose reductions. Overall median PFS was 19.2 months (CI-95% 14.3-NR). Patients with one or more dose reductions did not have decreased median PFS (19.2 months, CI-95% 14.3-NR compared to 12.2 months, CI-95% 7.3-NR, p = 0.078). Frequency of adverse events were as previously reported, with grade III and IV neutropenia occurring in 45.3% and 7% of patients, respectively. Patients treated with fulvestrant versus an aromatase inhibitor and patients with lymph node involvement at baseline had lower odds of requiring a dose reduction (OR_a = 0.30, CI-95% 0.12-0.73 & OR_a = 0.41, CI-95% 0.18-0.89, respectively).

CONCLUSION

Our results indicate that dose reduction of ribociclib is safe and do not compromise the efficacy of the treatment. Furthermore, the study supports translation of results from the MONALEESA trials to patients treated in real-world clinical settings.