A Turkish man pleaded guilty Tuesday in U.S. federal court to smuggling counterfeit, adulterated and misbranded cancer drugs into the U.S., including a version of the cancer drug Avastin that isn't approved for sale in the U.S., the Justice Department said.

Ozkan Semizoglu, who worked for a Turkish drug wholesaler, smuggled the cancer drugs to the U.S. in small parcels that were falsely labeled as "gifts," according to a copy of his plea agreement filed in federal court in the Eastern District of Missouri in St. Louis. Some of the drugs he shipped had counterfeit packaging and vial labeling. Mr. Semizoglu's shipping methods often did not maintain the drugs at temperatures low enough to maintain their quality, according to the plea agreement.

Mr. Semizoglu is set for sentencing on Oct. 28. His lawyer, David Bruns, said Tuesday that his client has "taken responsibility for what he did." The two counts of smuggling to which he has pleaded guilty carry maximum prison sentences of five and 20 years. Mr. Semizoglu couldn't be reached for comment.

Some of the drugs Mr. Semizoglu smuggled to the U.S. were labeled as Altuzan, the brand name Avastin carries in Turkey, according to the plea agreement. Both brands contain the same active ingredient and are sold by Roche Holding AG . But only Avastin, not Altuzan, is approved by the Food and Drug Administration for U.S. sale.

Nonetheless, some U.S. doctors in recent years have purchased cancer drugs not approved for U.S. sale because they are often cheaper than approved brands. The doctors buy the drugs from wholesalers who are often based overseas, and administer them to patients via injection or infusion. Several doctors have been criminally convicted for these purchases.