Ma Xun, Wong Sandy W, Zhou Ping, Chaulagain Chakra P, Doshi Parul, Klein Andreas K, Sprague Kellie, Kugelmass Adin, Toskic Denis, Warner Melissa, Miller Kenneth B, Lee Lisa, Varga Cindy, Comenzo Raymond L
1The John C Davis Myeloma and Amyloid Program in the Division of Hematology-Oncology, Department of Medicine, Tufts Medical Center, 800 Washington Street, Box 826, Boston, MA 02111 USA.
2Division of Hematology and Blood and Marrow Transplantation, Department of Medicine, University of California, San Francisco, CA USA.
Exp Hematol Oncol. 2018 Oct 16;7:27. doi: 10.1186/s40164-018-0119-4. eCollection 2018.
The monoclonal antibody daratumumab, approved for treating myeloma, targets CD38, a protein on myeloma and also on CD34+ hematopoietic progenitor cells. Because mobilized CD34+ cells are critical for stem cell transplant, we investigated the in vitro activity of daratumumab on mobilized CD34+ cells from myeloma patients with no prior exposure to daratumumab.
We determined the number of CD38 molecules per CD34+ cell, and whether daratumumab bound to CD34+ cells, whether C1q bound to daratumumab-coated CD34+ cells and whether daratumumab-related complement-dependent cytotoxicity (CDC) occurred. We also examined CD34+ cell progenitor cell colony capacity in assays with pre-plating incubation of CD34+ cells with daratumumab alone or with daratumumab and the CD59 inhibitory antibody BRIC229, and also assessed CD34+ cell responses to increasing doses of daratumumab in caspase 3/7 activity assays.
Although 75% of mobilized CD34+ cells co-express CD38, CD38 was minimally present on CD34+ cells compared to Daudi and KG-1 controls, C1q did not bind to daratumumab-coated CD34+ cells, and CDC did not occur. CD34+ cells incubated in complement-rich human serum with daratumumab alone or with daratumumab and BRIC229, and then plated in progenitor cell assays, produced similar numbers of colonies as controls. In progenitor cell assays with cryopreserved or fresh unselected or CD34-selected cells, daratumumab did not affect progenitor cell capacity, and in caspase 3/7 activity assays CD34+ cells were not affected by increasing doses of daratumumab.
In vitro, daratumumab is not toxic to mobilized CD34+ progenitor cells from myeloma patients.
单克隆抗体达雷妥尤单抗已获批用于治疗骨髓瘤，其靶向CD38，该蛋白存在于骨髓瘤细胞以及CD34+造血祖细胞表面。由于动员的CD34+细胞对干细胞移植至关重要，我们研究了达雷妥尤单抗对未接触过该药物的骨髓瘤患者动员的CD34+细胞的体外活性。
我们测定了每个CD34+细胞上CD38分子的数量，以及达雷妥尤单抗是否与CD34+细胞结合，C1q是否与包被达雷妥尤单抗的CD34+细胞结合，以及是否发生与达雷妥尤单抗相关的补体依赖性细胞毒性（CDC）。我们还在将CD34+细胞单独与达雷妥尤单抗或与达雷妥尤单抗及CD59抑制性抗体BRIC229进行预铺板孵育的试验中，检测了CD34+细胞祖细胞集落形成能力，并在半胱天冬酶3/7活性试验中评估了CD34+细胞对递增剂量达雷妥尤单抗的反应。
尽管75%的动员CD34+细胞共表达CD38，但与Daudi和KG-1对照相比，CD34+细胞上的CD38含量极少，C1q未与包被达雷妥尤单抗的CD34+细胞结合，且未发生CDC。在富含补体的人血清中，单独用达雷妥尤单抗或与达雷妥尤单抗及BRIC229一起孵育CD34+细胞，然后接种于祖细胞试验中，其形成的集落数量与对照相似。在使用冷冻保存或新鲜的未分选或CD34分选细胞进行的祖细胞试验中，达雷妥尤单抗不影响祖细胞能力，且在半胱天冬酶3/7活性试验中，CD34+细胞不受递增剂量达雷妥尤单抗的影响。
在体外，达雷妥尤单抗对骨髓瘤患者动员的CD34+祖细胞无毒。
