Purpose: The high cost of oncology drugs threatens the affordability of cancer care. Previous research identified drivers of price growth of targeted oral anticancer medications (TOAMs) in private insurance plans and projected the impact of closing the coverage gap in Medicare Part D in 2020. This study examined trends in TOAM prices and patient out-of-pocket (OOP) payments in Medicare Part D and estimated the actual effects on patient OOP payments of partial filling of the coverage gap by 2012. Methods: Using SEER linked to Medicare Part D, 2007 to 2012, we identified patients who take TOAMs via National Drug Codes in Part D claims. We calculated total drug costs (prices) and OOP payments per patient per month and compared their rates of inflation with general health care prices. Results: The study cohort included 42,111 patients who received TOAMs between 2007 and 2012. Although the general prescription drug consumer price index grew at 3% per year over 2007 to 2012, mean TOAM prices increased by nearly 12% per year, reaching $7,719 per patient per month in 2012. Prices increased over time for newly and previously launched TOAMs. Mean patient OOP payments dropped by 4% per year over the study period, with a 40% drop among patients with a high financial burden in 2011, when the coverage gap began to close. Conclusion: Rising TOAM prices threaten the financial relief patients have begun to experience under closure of the coverage gap in Medicare Part D. Policymakers should explore methods of harnessing the surge of novel TOAMs to increase price competition for Medicare beneficiaries.