Cyclophosphamide and Alemtuzumab In Lymphoma

This research study is a Phase I clinical trial, which tests the safety of an investigational intervention and also tries to define the appropriate dose of the investigational intervention to use for further studies. "Investigational" means that the intervention is being studied. The FDA (the U.S. Food and Drug Administration) has not approved alemtuzumab for aggressive lymphoma but it has been approved for other uses. In this research study, the investigators are studying the combination of cyclophosphamide and alemtuzumab in participants with several types of aggressive lymphoma which are positive for a protein called CD52, the target of alemtuzumab. Studies in laboratory models of CD52 positive lymphoma showed the combination of cyclophosphamide and alemtuzumab was very effective. Cyclophosphamide causes a specific type of immune cell, called a macrophage, to attack lymphoma cells treated with alemtuzumab. Both drugs have been used in participants with lymphoma but have not been previously combined in this way. The investigators hope to identify the highest dose of the drugs that can be safely given together and to see if the combination if effective in treating these lymphomas.