Page 68 - 2021_10-Haematologica-web

B. Cieniewicz et al.
cally the core binding factor translocations t(8;21)(RUNX1-RUNX1T1) and inv(16), were consistently overrepresented within the IR and R pAML containing cluster. Despite the typically more favorable prognosis for pAML with core binding factor translocations,4 these pAML could evade T-cell killing in vitro. While the role of core binding factor translocations in immune evasion is not well understood, it has been observed these lesions can impair naural killer (NK) cell surveillance of target cells through downregulation of CD48, an NK cell ligand.43 Conversely, in the S containing cluster, there was enrich- ment of patients with MLL rearrangements that historical- ly have intermediate to poor outcome. MLL rearrange- ments account for 15-20% of all pAML cases,44 but only 3% of adult AML,45 which suggest that LV-10 cells may be uniquely suited for the treatment of a common pAML subset. Further analysis of the sensitivity of specific sub- sets of pAML to LV-10 mediated killing may improve our ability to identify key genes responsible for the sensitivity of these pAML subsets.
We also identified CD200 as upregulated on IR and R pAML. CD200 has previously been associated with poor patient outcomes in adult AML.24,25 CD200 is a membrane glycoprotein that induces an inhibitory signal upon binding to its cognate inhibitory receptor CD200R1, and impairs degranulation in mast cells and CD8+ T cells.37,38 CD200R1 is expressed on both LV-10 and control LV-GFP cells. CD200 has negligible baseline expression on killing-sensitive ALL- CM, U937, and THP-1 myeloid cell lines (data not shown). We found that the overexpression of CD200 on ALL-CM and U937 cell lines led to a significant impairment in LV-10 degranulation, and in one cell line, CD200 overexpression also increased AML survival in the killing assay. CD200 effect on LV-10 degranulation was specific to CD200/CD200R1 interaction, as the degranulation increased upon CD200R1 blockade. Interestingly, CD200 expression also impaired the response of the Teff-like control LV-GFP cells. These results, together with reports showing that CD200 expression on AML can impair CD8+ T-cell func- tion,38 support the role of CD200 signaling in the impairment of cytotoxic T-cell degranulation. Notably, LV-10-mediated degranulation and killing of CD200-overexpressing AML cell lines were only impaired, not completely abolished, again suggesting that resistant pAML express multiple genes that contribute to their evasion of LV-10 killing.
Our observation that LV-10 cells can eliminate a large sub- set of pAML, together with our previously published data showing their ability to eliminate AML cell lines in vivo, sup- port their use as a novel therapy for high-risk pAML patients receiving allo-HSCT.13 We foresee the two potential uses of LV-10 cells in the clinic. First, donor-derived LV-10 cells could be used alongside allo-HSCT, acting early to prevent GvHD and combat residual AML. Alternatively, LV-10 can be used for their GvL effect when the patients’ own immune cells are depleted. Patients who are minimal residual disease pos- itive after induction chemotherapy have an abysmal prog- nosis, with only 10% disease-free survival.46 In those
patients, LV-10 cells could be used as a less toxic alternative to another round of induction chemotherapy prior to allo- HSCT. LV-10 would eliminate residual AML blasts, while persisting 2-3 weeks in vivo without eliciting GvHD (our unpublished data in humanized mice), until the patient’s own immune system reconstitutes. Notably, to mediate killing, LV-10 cells do not need to recognize specific antigens on their target cells through the TCR,13,18 uncoupling their cytotoxicity from HLA-II match or mismatch. We are in the process of further investigating mechanisms of LV-10 recog- nition of AML, and their potential therapeutic applications with in vivo models, in preparation for the transition of LV- 10 cell therapy to the clinic.
In conclusion, we show that LV-10 cells can directly medi- ate killing of pAML, especially those with an activated, mature myeloid gene expression profile. pAML resistance to killing was associated with expression of CD200, an immunomodulatory protein associated with poor AML prognosis,25 which could impair LV-10 cytotoxic responses. It is possible that by blocking the effect of these resistance factors, we may reverse resistance to LV-10-mediated killing. Altogether, our previous work and current findings imply that LV-10 cell therapy might be well suited to treat pAML by providing both a GvL effect and preventing GvHD, thus improving the outcome for many children with high risk pAML.
Disclosures
No conflicts of interest to disclose.
Contributions
BC, MJU, SG, NJL, AMC and MGR designed the research; BC, MJU, PC, JML, KG and ECS performed experiments; BC, MJU,PC,GA,RB,AB,AMCandMGRanalyzedthedata;BC, MJU, AB, NJL, AMC and MGR wrote the paper.
Acknowledgments
We would like to thank the Bass Center Tissue Bank staff mem- bers for preparing patient samples and data, and Drs. Ravindra Majeti, Tian Zhang, Yusuke Nakauchi, Daniel Thomas, Robertson Parkman, and Rhonda Perriman for helpful discussions, and Drs. Nicole Baldwin, Jacob Cardenas, Jinghua Gu, as well as Cynthia Smitherman and Phuong Nguyen from the Genomics and Biostatistics Cores of the Baylor Institute for Immunology Research in Dallas, TX, for RNA sample processing, RNA sequencing and initial data analysis.
Funding
This work was supported by a Rising Tide Foundation for Clinical Cancer Research, Curesearch for Children’s Cancer Acceleration Initiative grant, Emerson Collective Cancer Research Fund, Alex’s Lemonade Stand Reach Grant, Children’s Leukemia Research Association, the CURE Childhood Cancer Foundation, and the Virginia and D.K. Ludwig Fund for Cancer Research. BC was supported by the Maternal and Child Health Research Institute Postdoctoral Fellowship. MJU was supported by an NSF DGE (1147470) and Blavatnik Family Fellowship.
References
1. Vedi A, Mitchell R, Shanmuganathan S, et al. Increased survival for children with acute myeloid leukemia results from improved postrelapse treatment. J Pediatr Hematol
Oncol. 2018;40(7):541-547.
2. Ravindranath Y, Chang M, Steuber CP, et al.
Pediatric Oncology Group (POG) studies of acute myeloid leukemia (AML): a review of four consecutive childhood AML trials con- ducted between 1981 and 2000. Leukemia. 2005;19(12):2101-2116.
3. Sander A, Zimmermann M, Dworzak M, et al. Consequent and intensified relapse ther- apy improved survival in pediatric AML: results of relapse treatment in 379 patients of three consecutive AML-BFM trials. Leukemia. 2010;24(8):1422-1428.
4. Creutzig U, van den Heuvel-Eibrink MM,
2596
haematologica | 2021; 106(10)