Participants who are receiving or have received any other investigational agents within days of enrollment Participants may not be receiving any other study agents Participants may not be receiving any other study agents Participants may not be receiving any other investigational agents; patients may not be receiving any other treatment for their rectal cancer during study participation and within days prior to study treatment Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents during the proposed treatment cycle. Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants may not be receiving any other investigational agents Participants may not be receiving any other research study agents Participants may not be receiving any other study agents for at least days prior to enrollment Participants may not be receiving any other investigational study agents or treatment for their cancer Participants may not be receiving any other investigational agents Participants who are receiving any other investigational agents. Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents within days of the first dose of study drug Participants who are receiving any other investigational agents Participants may not be receiving any other investigational agents Participants who are receiving any other investigational agents Participants may not be receiving any other study agents Participants may not be receiving any other study agents STRATUM A: Participants receiving any other investigational agents STRATUM B: Participants receiving any other investigational agents STRATUM C: Participants receiving any other investigational agents Participants may not be receiving any other investigational agents targeting histiocytosis Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants may not be receiving any other study agents Participants may not be receiving any other study agents, and may not have received any other investigational agents within months prior to study entry Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants may not be receiving any other investigational agents Participants may not be receiving any other investigational agents Participants may not be receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any investigational agents are not eligible Participants receiving any other investigational agents Participants may not be receiving any other investigational agents Participants who are receiving any other investigational agents Participants may not be receiving any other investigational agents for treatment of their cancer Participants may not be receiving any other investigational agents Participants who are receiving any other investigational agents Participants receiving any other investigational agents Participants who are receiving any other investigational agents after ASCT Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents within days before the first dose of study drug Participants may not be receiving any other investigational agents Participants who are receiving any other investigational agents Participants may not be receiving any other study agents PHASE I: Participants may not be receiving any other study agents within weeks of initiating treatment PHASE II: Participants may not be receiving any other investigational agents Participants may not be receiving any biologics or investigational agents within weeks Participants receiving any other investigational agents Participants who are receiving any other investigational agents Participants receiving any other study agents Participants may not be receiving any other investigational anticancer agents Participants may not be receiving any other study agents Participants may not be receiving any other study agents Participants may not be receiving any other study agents. Participants may not be receiving any other study agents Participants may not be receiving any other study agents Participants may not be receiving any other study agents Participants may not be receiving any other study agents Participants may not be receiving any other investigational agents Participants may not be receiving any other study agents Participants may not be receiving any other investigational agents Participants may not be receiving any other study agents Participants may not be receiving any other study agents during the study or within weeks of the start of the trial Participants who are receiving concurrent therapy with other investigational agents Participants may not be receiving any other investigational agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants receiving any other anti-cancer or investigational agents Participants may not be receiving any other study agents Participants may not be receiving any other study agents at the time of first treatment Participants may not be receiving other investigational agents. Participants may not be receiving any other study agents Participants who are receiving any other investigational agents Participants who are receiving any other investigational agents Participants may not be receiving any other study agents Participants who are receiving any other investigational agents Participants may not be receiving any other investigational agents within days of enrollment or during this study Participants who are receiving any other investigational agents Research participants receiving any other investigational agents Participants who are receiving any other investigational agents; participants who are receiving standard of care induction therapy on a clinical trial may be eligible after discussion with the overall principal investigator Participants who are receiving any other investigational agents Participants receiving any other investigational agents Participants may not be receiving any other investigational agents for treatment of GVHD or underlying disease for at least days Participants may not be receiving investigational agents Participants may not be receiving any other investigational agents Participants may not be receiving any other investigational agents Participants may not be receiving any other investigational agents Participants who are receiving any other investigational agents Participants receiving any other investigational agents Participants may not be receiving any other investigational agents Participants may not be receiving any other investigational agents within past months Participants may not be receiving any other investigational agents Participants may not be receiving any other investigational agents during the study Participants may not be receiving any other investigational agents Participants may not be receiving any other investigational agents Participants who are receiving any other investigational agents Participants receiving other investigational agents Participants who are receiving any other investigational agents