Change in parenchymal intracranial (Panel A1) and extracranial (Panel B) tumor size and best overall response, and duration of exposure to abemaciclib (Panel C) in cohort C (HR+, HER2- and HR+, HER2+ MBC with LM). 1Panel A is only for patients with HR+, HER2- MBC with LM, as the patients with HR+, HER2+ MBC had no intracranial parenchymal lesions or post-baseline scans. Note: Patients who did not have an intracranial or extracranial lesion or a post-baseline scan are not shown on waterfall plots. oIndicates patient received prior whole brain radiotherapy. +Indicates patient received prior stereotactic radiosurgery. #Indicates patient received concomitant endocrine therapy. Abbreviations: CR, complete response; HER2+/â^', human epidermal growth factor receptor-2 positive/negative; HR+, hormone receptor positive; MBC, metastatic breast cancer; LM, leptomeningeal metastases; NE, not estimable; PD, progressive disease; PR, partial response; SD, stable disease.