TY - JOUR T1 - Target organ dose range-based, high-activity Zevalin®-inclusive non-myeloablative conditioning for allogeneic stem cell transplantation: a stratified approach JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1453 LP - 1453 VL - 57 IS - supplement 2 AU - William Erwin AU - Issa Khouri AU - Dustin Gress AU - Srinivas Kappadath AU - Aaron Jessop Y1 - 2016/05/01 UR - http://jnm.snmjournals.org/content/57/supplement_2/1453.abstract N2 - 1453Objectives To stratify the mCi/kg prescription for high-activity 90Y-Zevalin plus chemotherapy, non-myeloablative conditioning for allogeneic stem cell transplantation (ASCT) in B-cell malignancies, based on a target dose range to the most exposed organ. Methods Pre-treatment dosimetric assessment was performed on twenty patients, based on serial 111In-Zevalin whole body scanning (0, 4, 24, 72 and 144 hours), to select from among five mCi/kg prescriptions (0.5, 0.75, 1, 1.25 or 1.5) that would result in an estimated 10 - 12 Gy dose to the liver, lungs or kidneys. Organ dose was corrected for patient-specific mass, based on a CT volume estimate times 1.03 g/cc for liver and kidneys and a variable specific gravity for lungs (Busse et al, Med Phys, 2013)1. Although not of concern in this treatment scenario, marrow dose was estimated, but employing a previously developed whole body image-based method (Erwin, J Nucl Med, 2010)2 rather than the conventional blood-based method. Results The most exposed organ was either liver (16 patients) or lungs (4 patients). The distribution among the five prescriptions (smallest to largest) was 2, 4, 12, 1 and 1, with a mean of 0.94±0.23 mCi/kg. The estimated marrow dose was 2.60±0.69 Gy (range: 1.4-3.6). Treatment toxicities were not significantly high in any of the twenty patients. If all twenty patients were treated at 1 mCi/kg (the most common prescription), the 20 Gy limit employed for the Zevalin clinical trials prior to approval would have been exceeded in only one patient for the liver (22.9 Gy) or lungs (20.9 Gy). The maximum liver and lung doses at 0.75 mCi/kg would be 17.2 and 15.7 Gy, respectively. Conclusions The results of this stratification indicate that dose-intense Zevalin-inclusive, non-myeloablative conditioning for ASCT at a fixed mCi/kg level without dosimetry and an acceptable radiation risk to the most exposed organ may be possible. ER -