Total marrow lymphoid irradiation and cyclophosphamide is associated with low toxicity and good outcomes in patients undergoing hematopoietic stem cell transplantation for acute lymphoblastic leukemia and chronic myeloid leukemia in lymphoid blast crises – A phase I study

Introduction: Total marrow lymphoid irradiation (TMLI) can deliver higher doses of irradiation without increasing toxicity compared to Total body irradiation (TBI). Methods: Twenty adult patients undergoing hematopoietic stem cell transplantation (HSCT) for acute lymphoblastic leukemia (ALL) and chronic myeloid leukemia with lymphoid blast crises (CML‐LBC) received TMLI and cyclophosphamide for conditioning. Ten patients each received 13.5 or 15 Gy of TMLI. The graft source was peripheral blood stem cells in all, and donors included matched related (n = 15), haplo‐identical (n = 3) or matched unrelated donors (n = 2). Results: The median cell dose infused was 9 × 106 CD34/kg (range 4.8–12.4). Engraftment occurred in all (100%) at a median of 15 days (range: 14–17). Toxicity was low with hemorrhagic cystitis seen in two but no sinusoidal obstruction syndrome. Acute GVHD occurred in 40% while chronic GVHD was seen in 70.5%. Viral infections were seen in 55% while blood stream bacterial infections occurred in 20% and invasive fungal disease (IFD) in 10%. The Day 100 non‐relapse mortality (NRM) was 10%. At a median follow up of 25 months (range 2–48), two patients have relapsed. Overall survival at 2 years is 80% while the disease‐free survival is 75%. Conclusions: The combination of TMLI and cyclophosphamide for myeloablative conditioning is associated with low toxicity and favorable early outcomes in patients undergoing HSCT for ALL and CML‐LBC. [ABSTRACT FROM AUTHOR]