 Study Design: This is an open-label, dose exploration study evaluating AMG 232 in subjects with advanced p53WT solid tumors or multiple myeloma. The study will be conducted in 2 parts: Part 1 - Dose Exploration parts 1a, 1b and 1c and Part 2 - Dose Expansion. Part 1a is aimed at evaluating the safety, tolerability, PK and PD of AMG 232 and determining the MTD of a 7-day once daily QD dosing schedule in subjects with advanced solid tumors using a practical continuous reassessment method CRM. Part 1b will evaluate the safety and tolerability of 3-day QD dosing schedule or alternate dosing schedule based upon emerging data with a particular emphasis on evaluating the tolerability of daily doses equal to or higher than the part 1a MTD in subjects with solid tumors or multiple myeloma. Part 1c will evaluate the safety and tolerability of 7-day twice daily BID dosing schedule with daily cumulative doses equal to or higher than the part 1a MTD in subjects with solid tumors. The dose expansion part of the study Part 2 can open once the MTD has been determined in Part 1a. Part 2, part 1b and part 1c can be explored in parallel. The dose expansion part will consist of up to 85 additional subjects with specific tumors harboring MDM2 amplification liposarcoma LPS, gliobastoma GBM and all other solid tumors or potentially harboring MDM2 overexpression ER metastatic breast cancer and a group of subjects with multiple myeloma. 