This study will provide information regarding the metabolic pathway of GBT440, the need for evaluation of potential drug-drug interactions, and the need for studies in special populations. The administration of radiolabeled drug is necessary to fully characterize the rates and routes of elimination of GBT440, providing further quantitative information on the disposition of GBT440. The results from this study will permit a comprehensive comparison between animal and human routes of elimination and metabolic profiles of GBT440.

Inclusion Criteria:

1. Healthy; non-smoking male; 18 to 55 years old, inclusive
2. Weighs at least 50 kg and not more than 110 kg
3. Agrees to use contraception
4. Willing and able to give written informed consent

Exclusion Criteria:

1. Evidence or history of clinically significant metabolic, allergic, dermatological, hepatic, renal, hematological, pulmonary, cardiovascular, gastrointestinal, neurological, or psychiatric disorder
2. History of stomach or intestinal surgery that would potentially alter drug absorption
3. History of hypersensitivity or allergy to drugs, foods, or other substances
4. History or presence of abnormal electrocardiogram
5. Exposure to significant radiation or participated in more than 1 other radiolabeled study drug trial within 12 months of Screening
6. Participated in another clinical trial of an investigational drug within 30 days (or 5 half-lives of the investigational drug, whichever is longer) prior to Screening