First Report of Non-Genotoxic Conditioning with JSP191 (anti-CD117) and Hematopoietic Stem Cell Transplantation in a Newly Diagnosed Patient with Severe Combined Immune Deficiency

Successful hematopoietic stem cell transplantation (HSCT) requires vacating recipient hematopoietic stem cell (HSC) niches in the bone marrow to permit donor HSC engraftment that can provide life-long hematopoietic and immune function. Currently, HSCT in SCID relies on DNA damaging chemotherapy to eliminate recipient HSC and achieve niche clearance. We have pursued a non-toxic approach to target and deplete HSC using a humanized monoclonal antibody, JSP191, that binds human CD117 (c-Kit). We previously showed the safety and successful HSC engraftment in a Phase 1 trial of the first 6 patients with severe combined immunodeficiency (SCID), who underwent a second transplant because of HSC engraftment failure and poor immunity after their first transplantation. In these re-transplant patients even a low level of stringently measured myeloid chimerism resulted in significant and sustained generation of naive T cells and clinical improvement. Based on these results, the study of JSP191 (NCT#02963064)has opened a cohort of newly diagnosed infants with SCID. Here we report data from the first patient in this cohort, a SCIDX1 patient who received a primary HSCT with haploidentical CD34+ cells after conditioning with JSP 191. The patient had a c.270-15A>G variant in the IL2RG gene, which is predicted to cause a null phenotype. Besides a T- B+ NK- phenotype typical of SCIDX1 including dysfunctional B cells, the patient had anemia and intermittent neutropenia and thrombocytopenia. Despite evidence of maternal T cell engraftment, the patient had no clinical graft-versus-host disease (GVHD). The patient was initially enrolled in a trial of lentiviral gene therapy, but harvested bone marrow cells died in vitro during transduction and culture. The patient also mobilized poorly with G-CSF/Plerixafor. Further investigation revealed heterozygosity for loss-of-function mutations in two genes involved in DNA repair, BRCA1 and RAD51; Diepoxybutane (DEB) breakage study showed greater than normal pathologic chromosomal breaks, but less than that seen in Fanconi anemia. Because of concern for possible hypersensitivity to alkylating agent-based conditioning, the patient was referred for transplant with JSP191 conditioning. The patient received a CD34+ peripheral blood HSCT from his father after conditioning with 0.3 mg/kg of JSP 191 antibody intravenously over an hour on Day -8 and rATG (Thymoglobulin) on Day -5, -4, -3 and -2 (3.5 mg/kg total) to prevent rejection by the maternal T cells. The cryopreserved donor CD34+ cells were administered after sufficient clearance of the JSP191 serum level. The antibody infusion was well tolerated without toxicity, and the post-transplant course was uneventful without acute toxicities or GVHD. As a surrogate marker for HSC engraftment, CD15+ myeloid cells from peripheral blood were stringently sorted by flow cytometry and donor levels were quantified by short-tandem repeat (STR) analysis. Progressive levels of myeloid engraftment were observed beginning at Week 4. The level of donor chimerism at 12 weeks was 8% in the sorted CD15+ blood cells, and a marrow aspirate showed 25% donor CD34+ cells. By 3 months pre-existing abnormal CD19-CD20+ host B lymphocytes were significantly reduced, and CD19+ donor-derived B lymphocytes were emerging. At 2 months, CD4+ recent thymic emigrant and naïve T lymphocytes were observed, and by 3 months, overall T and NK lymphocyte numbers were 390/uL and 117/uL, respectively. Normal blastogenic responses to the T cell mitogen PHA were observed at 3 months. These first-in-class results provide proof of concept of the safety and efficacy of the use of JSP191 antibody to clear host marrow niche space to enable sufficient donor HSC engraftment and immune reconstitution as primary therapy of SCID. Non-genotoxic conditioning with JSP191 may replace conventional conditioning for newly diagnosed infants with SCID, thereby avoiding toxicities of chemotherapy. Disclosures Kohn: Allogene Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Consultancy, Patents & Royalties, Research Funding. De Oliveira:Orchard Therapeutics: Research Funding; bluebird bio, Inc.: Research Funding. Czechowicz:Rocket Pharmaceuticals, Inc.: Research Funding. Brown:Merck: Membership on an entity's Board of Directors or advisory committees; Ansun: Membership on an entity's Board of Directors or advisory committees; Cidara: Membership on an entity's Board of Directors or advisory committees; Allogene: Membership on an entity's Board of Directors or advisory committees; Cellerant Therapeutics: Membership on an entity's Board of Directors or advisory committees. Shizuru:Jasper Therapeutics, Inc: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees.

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Lower Hematopoietic Progenitor Cell Counts and Yields at Subsequent Donations Is Influenced By a Shorter Inter-Donation Interval between the First and Subsequent Mobilizations

Blood ◽

10.1182/blood-2019-123492 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1962-1962

Author(s):

Sandhya R. Panch ◽

Brent R. Logan ◽

Jennifer A. Sees ◽

Bipin N. Savani ◽

Nirali N. Shah ◽

...

Keyword(s):

Stem Cell ◽

Board Of Directors ◽

Peripheral Blood ◽

Research Funding ◽

Time Interval ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Peripheral Blood Cd34 ◽

Cell Counts ◽

Cd34 Cells

Introduction: Approximately 7% of unrelated hematopoietic stem cell (HSC) donors are asked to donate a subsequent time to the same or different recipient. In a recent large CIBMTR study of second time donors, Stroncek et al. incidentally found that second peripheral blood stem cell (PBSC) collections had lower total CD34+ cells, CD34+ cells per liter of whole blood processed, and CD34+ cells per kg donor weight. Based on smaller studies, the time between the two independent PBSC donations (inter-donation interval) as well as donor sex, race and baseline lymphocyte counts appear to influence CD34+ cell yields at subsequent donations. Our objective was to retrospectively evaluate factors contributory to CD34+ cell yields at subsequent PBSC donation amongst NMDP donors. Methods. The study population consisted of filgrastim (G-CSF) mobilized PBSC donors through the NMDP/CIBMTR between 2006 and 2017, with a subsequent donation of the same product. evaluated the impact of inter-donation interval, donor demographics (age, BMI, race, sex, G-CSF dose, year of procedure, need for central line) and changes in complete blood counts (CBC), on the CD34+ cell yields/liter (x106/L) of blood processed at second donation and pre-apheresis (Day 5) peripheral blood CD34+ cell counts/liter (x106/L) at second donation. Linear regression was used to model log cell yields as a function of donor and collection related variables, time between donations, and changes in baseline values from first to second donation. Stepwise model building, along with interactions among significant variables were assessed. The Pearson chi-square test or the Kruskal-Wallis test compared discrete variables or continuous variables, respectively. For multivariate analysis, a significance level of 0.01 was used due to the large number of variables considered. Results: Among 513 PBSC donors who subsequently donated a second PBSC product, clinically relevant decreases in values at the second donation were observed in pre-apheresis CD34+ cells (73.9 vs. 68.6; p=0.03), CD34+cells/L blood processed (32.2 vs. 30.1; p=0.06), and total final CD34+ cell count (x106) (608 vs. 556; p=0.02). Median time interval between first and second PBSC donations was 11.7 months (range: 0.3-128.1). Using the median pre-apheresis peripheral blood CD34+ cell counts from donation 1 as the cut-off for high versus low mobilizers, we found that individuals who were likely to be high or low mobilizers at first donation were also likely to be high or low mobilizers at second donation, respectively (Table 1). This was independent of the inter-donation interval. In multivariate analyses, those with an inter-donation interval of >12 months, demonstrated higher CD34+cells/L blood processed compared to donors donating within a year (mean ratio 1.15, p<0.0001). Change in donor BMI was also a predictor for PBSC yields. If donor BMI decreased at second donation, so did the CD34+cells/L blood processed (0.74, p <0.0001). An average G-CSF dose above 960mcg was also associated with an increase in CD34+cells/L blood processed compared to donors who received less than 960mcg (1.04, p=0.005). (Table 2A). Pre-apheresis peripheral blood CD34+ cells on Day 5 of second donation were also affected by the inter-donation interval, with higher cell counts associated with a longer time interval (>12 months) between donations (1.23, p<0.0001). Further, independent of the inter-donation interval, GCSF doses greater than 960mcg per day associated with higher pre-apheresis CD34+ cells at second donation (1.26, p<0.0001); as was a higher baseline WBC count (>6.9) (1.3, p<0.0001) (Table 2B). Conclusions: In this large retrospective study of second time unrelated PBSC donors, a longer inter-donation interval was confirmed to be associated with better PBSC mobilization and collection. Given hematopoietic stem cell cycling times of 9-12 months in humans, where possible, repeat donors may be chosen based on these intervals to optimize PBSC yields. Changes in BMI are also to be considered while recruiting repeat donors. Some of these parameters may be improved marginally by increasing G-CSF dose within permissible limits. In most instances, however, sub-optimal mobilizers at first donation appear to donate suboptimal numbers of HSC at their subsequent donation. Disclosures Pulsipher: CSL Behring: Membership on an entity's Board of Directors or advisory committees; Miltenyi: Research Funding; Bellicum: Consultancy; Amgen: Other: Lecture; Jazz: Other: Education for employees; Adaptive: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Medac: Honoraria. Shaw:Therakos: Other: Speaker Engagement.

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Inducible SBDS Deficiency Impairs Bone Marrow Niche Function to Engraft Donor Hematopoietic Stem Cell after Transplantation

Blood ◽

10.1182/blood-2019-121763 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3199-3199

Author(s):

Ji Zha ◽

Lori Kunselman ◽

Hongbo Michael Xie ◽

Brian Ennis ◽

Jian-Meng Fan ◽

...

Keyword(s):

Bone Marrow ◽

Stem Cell ◽

Mouse Model ◽

Board Of Directors ◽

Hematopoietic Stem Cell ◽

Graft Failure ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Bm Niche ◽

Deficient Mice

Hematopoietic stem cell (HSC) transplantation (HSCT) is required for curative therapy for patients with high-risk hematologic malignancies, and a number of non-malignant disorders including inherited bone marrow failure syndromes (iBMFS). Strategies to enhance bone marrow (BM) niche capacity to engraft donor HSC have the potential to improve HSCT outcome by decreasing graft failure rates and enabling reduction in conditioning intensity and regimen-associated complications. Several studies in animal models of iBMFS have demonstrated that BM niche dysfunction contributes to both the pathogenesis of iBMFS, as well as impaired graft function after HSCT. We hypothesize that such iBMFS mouse models are useful tools for discovering targetable niche elements critical for donor engraftment after HSCT. Here, we report the development of a novel mouse model of Shwachman-Diamond Syndrome (SDS) driven by conditional Sbds deletion, which demonstrates profound impairment of healthy donor hematopoietic engraftment after HSCT due to pathway-specific dysfunctional signaling within SBDS-deficient recipient niches. We first attempted to delete Sbds specifically in mature osteoblasts by crossing Sbdsfl/flmice with Col1a1Cre+mice. However, the Col1a1CreSbdsExc progenies are embryonic lethal at E12-E15 stage due to developmental musculoskeletal abnormalities. Alternatively, we generated an inducible SDS mouse model by crossing Sbdsfl/flmice with Mx1Cre+ mice, and inducing Sbds deletion in Mx1-inducible BM hematopoietic and osteolineage niche cells by polyinosinic-polycytidilic acid (pIpC) administration. Compared with Sbdsfl/flcontrols, Mx1CreSbdsExc mice develop significantly decreased platelet counts, an inverted peripheral blood myeloid/lymphoid cell ratio, and reduced long-term HSC within BM, consistent with stress hematopoiesis seen in BMF and myelodysplastic syndromes. To assess whether inducible SBDS deficiency impacts niche function to engraft donor HSC, we transplanted GFP+ wildtype donor BM into pIpC-treated Mx1CreSbdsExc mice and Sbdsfl/flcontrols after 1100 cGy of total body irradiation (TBI). Following transplantation, Mx1CreSbdsExc recipient mice exhibit significantly higher mortality than controls (Figure 1). The decreased survival was related to primary graft failure, as Mx1CreSbdsExc mice exhibit persistent BM aplasia after HSCT and decreased GFP+ reconstitution in competitive secondary transplantation assays. We next sought to identify the molecular and cellular defects within BM niche cells that contribute to the engraftment deficits in SBDS-deficient mice. We performed RNA-seq analysis on the BM stromal cells from irradiated Mx1CreSbdsExc mice versus controls, and the results revealed that SBDS deficiency in BM niche cells caused disrupted gene expression within osteoclast differentiation, FcγR-mediated phagocytosis, and VEGF signaling pathways. Multiplex ELISA assays showed that the BM niche of irradiated Mx1CreSbdsExc mice expresses lower levels of CXCL12, P-selectin and IGF-1, along with higher levels of G-CSF, CCL3, osteopontin and CCL9 than controls. Together, these results suggest that poor donor HSC engraftment in SBDS-deficient mice is likely caused by alterations in niche-mediated donor HSC homing/retention, bone metabolism, host monocyte survival, signaling within IGF-1 and VEGF pathways, and an increased inflammatory state within BM niches. Moreover, flow cytometry analysis showed that compared to controls, the BM niche of irradiated Mx1CreSbdsExc mice contained far fewer megakaryocytes, a hematopoietic cell component of BM niches that we previously demonstrated to be critical in promoting osteoblastic niche expansion and donor HSC engraftment. Taken together, our data demonstrated that SBDS deficiency in BM niches results in reduced capacity to engraft donor HSC. We have identified multiple molecular and cellular defects in the SBDS-deficient niche contributing to this phenotype. Such niche signaling pathway-specific deficits implicate these pathways as critical for donor engraftment during HSCT, and suggest their potential role as targets of therapeutic approaches to enhance donor engraftment and improve HSCT outcome in any condition for which HSCT is required for cure. Disclosures Olson: Merck: Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria.

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Plerixafor (Mozobil ®)Plus G-CSF Is Effective in Mobilizing Hematopoietic Stem Cells in Patients with Concurrent Thrombocytopenia Undergoing Autologous Hematopoietic Stem Cell Transplantation.

Blood ◽

10.1182/blood.v114.22.3229.3229 ◽

2009 ◽

Vol 114 (22) ◽

pp. 3229-3229 ◽

Cited By ~ 1

Author(s):

Ivana N Micallef ◽

Eric Jacobsen ◽

Paul Shaughnessy ◽

Sachin Marulkar ◽

Purvi Mody ◽

...

Keyword(s):

Stem Cell ◽

Platelet Count ◽

Board Of Directors ◽

Research Funding ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Platelet Counts ◽

Cd34 Cells ◽

Low Platelet Count ◽

Equity Ownership

Abstract Abstract 3229 Poster Board III-166 Introduction Low platelet count prior to mobilization is a significant predictive factor for mobilization failure in patients with non-Hodgkin's lymphoma (NHL) or Hodgkin's disease (HD) undergoing autologous hematopoietic stem cell (HSC) transplantation (auto-HSCT; Hosing C, et al, Am J Hematol. 2009). The purpose of this study is to assess the efficacy of HSC mobilization with plerixafor plus G-CSF in patients with concomitant thrombocytopenia undergoing auto-HSCT. Methods Patients who had failed successful HSC collection with any mobilization regimen were remobilized with plerixafor plus G-CSF as part of a compassionate use program (CUP). Mobilization failure was defined as the inability to collect 2 ×106 CD34+ cells/kg or inability to achieve a peripheral blood count of ≥10 CD34+ cells/μl without having undergone apheresis. As part of the CUP, G-CSF (10μg/kg) was administered subcutaneously (SC) every morning for 4 days. Plerixafor (0.24 mg/kg SC) was administered in the evening on Day 4, approximately 11 hours prior to the initiation of apheresis the following day. On Day 5, G-CSF was administered and apheresis was initiated. Plerixafor, G-CSF and apheresis were repeated daily until patients collected the minimum of 2 × 106 CD34+ cells/kg for auto-HSCT. Patients in the CUP with available data on pre-mobilization platelet counts were included in this analysis. While patients with a platelet count <85 × 109/L were excluded from the CUP, some patients received waivers and were included in this analysis. Efficacy of remobilization with plerixafor + G-CSF was evaluated in patients with platelet counts ≤ 100 × 109/L or ≤ 150 × 109/L. Results Of the 833 patients in the plerixafor CUP database, pre-mobilization platelet counts were available for 219 patients (NHL=115, MM=66, HD=20 and other=18.). Of these, 92 patients (NHL=49, MM=25, HD=8 and other=10) had pre-mobilization platelet counts ≤ 150 × 109/L; the median platelet count was 115 × 109/L (range, 50-150). The median age was 60 years (range 20-76) and 60.4% of the patients were male. Fifty-nine patients (64.1%) collected ≥2 × 109 CD34+ cells/kg and 13 patients (14.1%) achieved ≥5 × 106 CD34+ cells/kg. The median CD34+ cell yield was 2.56 × 106 CD34+ cells/kg. The proportion of patients proceeding to transplant was 68.5%. The median time to neutrophil and platelet engraftment was 12 days and 22 days, respectively. Similar results were obtained when efficacy of plerixafor + G-CSF was evaluated in 29 patients with platelet counts ≤ 100 × 109/L (NHL=12, MM=10, HD=3 and other=4). The median platelet count in these patients was 83 × 109/L (range, 50-100). The median age was 59 years (range 23-73) and 60.4% of the patients were male. The minimal and optimal cell dose was achieved in 19(65.5%) and 3(10.3%) patients, respectively. The median CD34+ cell yield was 2.92 × 106 CD34+ cells/kg. The proportion of patients proceeding to transplant was 62.1%. The median time to neutrophil and platelet engraftment was 12 days and 23 days, respectively. Conclusions For patients mobilized with G-CSF alone or chemotherapy ±G-CSF, a low platelet count prior to mobilization is a significant predictor of mobilization failure. These data demonstrate that in patients with thrombocytopenia who have failed prior mobilization attempts, remobilization with plerixafor plus G-CSF allows ∼65% of the patients to collect the minimal cell dose to proceed to transplantation. Thus, in patients predicted or proven to be poor mobilizers, addition of plerixafor may increase stem cell yields. Future studies should investigate the efficacy of plerixafor + G-CSF in front line mobilization in patients with low platelet counts prior to mobilization. Disclosures Micallef: Genzyme Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding. Jacobsen:Genzyme Corporation: Research Funding. Shaughnessy:Genzyme Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Marulkar:Genzyme Corporation: Employment, Equity Ownership. Mody:Genzyme Corporation: Employment, Equity Ownership. van Rhee:Genzyme Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Optimal Conditioning for Older Patients with Acute Myeloid Leukemia (AML) Receiving Allogeneic Hematopoietic Stem Cell Transplantation: A Propensity Score Analysis

Blood ◽

10.1182/blood-2019-123699 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 42-42 ◽

Cited By ~ 1

Author(s):

Stefan O. Ciurea ◽

Ankur Varma ◽

Piyanuch Kongtim ◽

Samer Srour ◽

Qaiser Bashir ◽

...

Keyword(s):

Stem Cell ◽

Hematopoietic Stem Cell Transplantation ◽

Board Of Directors ◽

Hematopoietic Stem Cell ◽

Older Patients ◽

Research Funding ◽

Conditioning Regimen ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Secondary Aml

Introduction Allogeneic hematopoietic stem cell transplantation (AHSCT) is increasingly performed for older patients with AML; however, the optimal conditioning regimen for these patients remains unclear. Methods: We retrospectively evaluated outcomes of 404 patients with AML, ≥60 years receiving AHSCT at our institution between 01/2005-08/2018 who received 4 conditioning regimens: 1) fludarabine+melphalan 100mg/m2 (FM100, N=78), 2) fludarabine+melphalan 140mg/m2 (FM140, N=89), 3) fludarabine+IV busulfan x 4 days with Bu AUC≥5,000/day (equivalent dose 130mg/m2/day) (Bu≥5,000, N=131), 4) fludarabine+IV busulfan x 4 days with Bu AUC 4,000/day (equivalent dose 110mg/m2/day) (Bu4,000, N=106). To adjust for potential selection bias in choices of conditioning regimen, propensity score was calculated and used as a stratifying variable in a multivariable Cox regression model. Factors included in the propensity score calculation were age, secondary AML, ELN2017 genetic risk, remission status before transplant, induction failure, donor type, stem cell source and KPS. Results are presented for the FM100, FM140, Bu≥5,000 and Bu4000, respectively. Median follow-up survivors were 40, 74, 30 and 44 months, respectively (p=0.06). Donors are matched sibling, matched unrelated, haploidentical and mismatched unrelated donor in 126 (31%), 218 (54%), 40 (10%) and 20 (5%) patients, respectively. Patients in the FM100 group were significantly older and had lower KPS. The median age was 67, 64, 64 and 65 years, respectively (p=0.001), while 51%, 32%, 27% and 27% had KPS<90%, respectively (p<0.001). The HCT-CI of ≥3 was present in 57%, 62%, 56% and 70%, respectively (p=0.33), while 42%, 78%, 47% and 51% had high and very high-risk DRI, respectively (p<0.001), and 12%, 46%, 18% and 32% of the patients were transplanted in active disease (p<0.001). No significant differences were seen in both cytogenetic and ELN2017 genetic risk. More patients in FM100 group were treated using a standard of care protocol (73%, 64%, 25% and 31%, respectively, p<0.001). Grade 2-4 aGVHD at day 100 were 26% vs. 26%, 36% and 40% (p=0.04), and extensive cGVHD at 3 years 14% vs. 42%, 36% and 37%, respectively (p=0.07). The NRM at 3 years were 19%, 29%, 25% and 21% (p=0.06), and 3-year relapse rates were 32% vs. 32%, 30% and 55%, respectively (p=0.003). Among 4 groups, FM100 group had a significantly better PFS and GRFS with 5-year PFS for these 4 groups were 44%, 30%, 33% and 22% (p=0.02) and 5-year GRFS were 28%, 20%, 18% and 9% (p=0.006), respectively (Figure 1). For subgroup of patients with KPS <90%, 5-year PFS were 41%, 27%, 28%, 22%, respectively (p=0.007), while there was no significant difference between 4 conditioning groups in patients with high-risk AML defined as either secondary AML, induction failure or high-risk cytogenetics/high ELN2017 risk, suggesting that a more intense conditioning is not beneficial in this group of patients. The survival benefit of FM100 persisted after adjusted for baseline factors, transplant characteristics as well as propensity scores in a multivariable analysis (MVA). In MVA for PFS, HR was 0.57 (p=0.013) for FM100, 0.68 (p=0.056) for FM140 and 0.77 (p=0.137) for Bu> 5000 as compared with Bu 4,000 group (Figure 1). In the MVA for GRFS, HR for FM100, FM140 and Bu> 5000 was 0.53 (p=0.005), 0.78 (p=0.196), and 0.81 (p=0.178), respectively as compared with Bu 4,000 group. Other factors that independently predicted PFS were secondary AML (HR 1.68, p=0.001), remission status before transplant (HR 1.82, p=0.048 for CR with MRD positive, HR 1.87, p=0.043 for CR with unknown MRD status and HR 2.86, p=0.001 for active disease at transplant as compared with CR with MRD negative), KPS (HR 0.98, p=0.005) and use of a mismatched unrelated donor (HR 2.46, p=0.001 compared with matched related donor transplant). Conclusions: Older patients with AML benefit from a reduced-intensity conditioning with FM100 conditioning regimen, which was associated with better survival despite the fact that patients who could not receive more intense conditioning preferentially received this regimen. Higher intensity conditioning does not appear to improve survival in older patients. Alternative approaches to increase in conditioning intensity are needed to improve survival in patients with AML receiving allogeneic hematopoietic stem cell transplantation. Disclosures Ciurea: Kiadis Pharma: Membership on an entity's Board of Directors or advisory committees, Other: stock holder; Miltenyi: Research Funding; Spectrum: Membership on an entity's Board of Directors or advisory committees; MolMed: Membership on an entity's Board of Directors or advisory committees. Bashir:Imbrium: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite: Membership on an entity's Board of Directors or advisory committees; Acrotech: Research Funding; StemLine: Research Funding; Spectrum: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Oran:Astex pharmaceuticals: Research Funding; AROG pharmaceuticals: Research Funding. Popat:Bayer: Research Funding; Incyte: Research Funding; Jazz: Consultancy. Konopleva:Stemline Therapeutics: Consultancy, Honoraria, Research Funding; Reata Pharmaceuticals: Equity Ownership, Patents & Royalties; Ablynx: Research Funding; Astra Zeneca: Research Funding; Agios: Research Funding; Ascentage: Research Funding; Calithera: Research Funding; Forty-Seven: Consultancy, Honoraria; Kisoji: Consultancy, Honoraria; Eli Lilly: Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Cellectis: Research Funding; Amgen: Consultancy, Honoraria; F. Hoffman La-Roche: Consultancy, Honoraria, Research Funding; Genentech: Honoraria, Research Funding.

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Effect of Daratumumab-Containing Induction on CD34+ Hematopoietic Stem Cells before Autologous Stem Cell Transplantation in Multiple Myeloma

Blood ◽

10.1182/blood-2021-150360 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 2764-2764

Author(s):

Ondrej Venglar ◽

Tereza Sevcikova ◽

Anjana Anilkumar Sithara ◽

Veronika Kapustova ◽

Jan Vrana ◽

...

Keyword(s):

Multiple Myeloma ◽

Stem Cell ◽

Board Of Directors ◽

Research Funding ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Platelet Recovery ◽

Cd34 Cells ◽

Fcm Analysis ◽

D 12

Abstract Introduction: Daratumumab (Dara) is an anti-CD38 monoclonal antibody representing a novel treatment agent for multiple myeloma (MM). Nonetheless, several studies have reported a Dara-related impairment of CD34+ hematopoietic stem cell (HSC) mobilization and post-autologous stem cell transplantation (ASCT) complications, including low yields of mobilized HSCs and delayed neutrophil engraftment. Impact of Dara on the mobilization process and HSCs remains poorly understood even though sufficient yields of CD34+ cells are necessary for a successful ASCT and subsequent patient recovery. Aims: To compare the effect of the Dara-containing (Dara-Bortezomib-Dexamethasone [D-VCd]) and conventional (Bortezomib-Thalidomide-Dexamethasone [VTd]) therapy on CD34+ HSCs. Methods: Transplant eligible MM patients were treated with D-VCd or VTd induction regimen followed by a cyclophosphamide + G-CSF mobilization and a high-dose melphalan D -1 before ASCT. Flow cytometry (FCM) screening of CD34+ subsets was performed in the bone marrow (BM) or apheresis product (AP) at three consecutive time points: 1) diagnostic BM (DG), 2) mobilization AP (MOB), 3) a day prior ASCT BM (D-1). Furthermore, RNA sequencing (RNAseq) of sorted CD34+ cells was performed on total RNA with ribo-depletion protocol in AP after the induction. D-VCd samples had lower RNA yields thus the D-VCd or VTd groups were processed as independent batches. Results: Clinical data revealed no significant differences in mobilization (p >0.050) likely due to a small cohort sizes (D-VCd n=5 vs VTd n=9), though a trend towards worse performance in D-VCd was observed. Median CD34+ cell yield was 3.08 vs 10.56 x 10 6/kg. Platelet recovery of >20x10 9/L was D+14 vs D+12 (range: 11-18 vs 10-16). Neutrophil recovery of >0.5x10 9/L was D+12 in both groups (range: 11-17 vs 11-12). In FCM analysis, DG (n=14), MOB D-VCd (n=5) vs VTd (n=9), D-1 D-VCd (n=7) vs VTd (n=15) were compared. CD34+ frequency (Fig. 1A) difference in MOB D-VCd vs VTd was insignificant (median: 1.15% vs 1.89%), whereas CD34+ fraction dropped in D-1 D-VCd (median: 0.52% vs 0.72%, p=0.027), albeit there was no significant reduction in D-1 D-VCd vs initial DG (median: 0.52% vs 0.45%). Differences in the distribution of certain HSC subsets were detected in the CD34+ pool (Fig. 1B-E). Frequency of multipotent progenitors (MPPs) (Fig. 1B) was increased in MOB D-VCd (median: 82.1% vs 66.2%, p=0.004). Frequency of lympho-myeloid-primed progenitor + granulocyte-monocyte progenitor (LMPP+GMP) (Fig. 1C) subset was reduced in D-VCd in both MOB (median: 1.7% vs 16.9%, p=0.042) and D-1 (median: 5.3% vs 14.0%; p=0.026). Erythro-myeloid progenitors (EMPs) (Fig. 1D) were reduced in MOB D-VCd (median: 10.7% vs 19.5%, p=0.042), while the frequency of EMPs increased in D-1 D-VCd (median: 20.8% vs 12.4%, p=0.045). No considerable differences were found in the expression of adhesion molecules CD44/HCAM or CD184/CXCR4. CD38 was strongly diminished in the whole D-VCd CD34+ fraction of MOB and D-1. To understand whether the differences in the mobilization efficacy after D-VCd induction were reflected in the expression profile of mobilized CD34+ cells, differential expression analysis was performed. Overall 133 significantly deregulated genes (p<0.05; log fold change >(-)1) between cohorts (D-VCd n=5 vs VTd n=5) were revealed (Fig. 2). Pathway analysis showed cellular response and localization as the most deregulated categories. The list of deregulated genes contained 25% of non-coding RNAs, some of which were linked to a protein localization in the cell (RN7SL1/2). The expression of adhesion molecules was inspected independently. Out of 59 HSC hallmark genes, only 8 were significantly altered in D-VCd. Interestingly, the main homing molecule CXCR4 seemed to be downregulated in D-VCd, while integrins A3 and B4 were upregulated. Conclusions: Despite the limited cohort sizes, a prospective trend of delayed neutrophil and platelet recovery was observed after D-VCd therapy. FCM analysis revealed a significant reduction of CD34+ subsets responsible, among others, for a reconstitution of neutrophils and megakaryocytes. A strong signal in transcriptome data which would potentially explain differential mobilization in D-VCd cohort was not detected, nevertheless, several genes with adhesive/homing and stem cell differentiation function were indeed altered. The results warrant further investigation. Figure 1 Figure 1. Disclosures Hajek: BMS: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Novartis: Consultancy, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharma MAR: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Targeting CXCR4, VLA4, and CXCR2 for Hematopoietic Stem Cell Mobilization

Blood ◽

10.1182/blood-2019-124373 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1916-1916

Author(s):

Daniel Cancilla ◽

Haresh Thakellapalli ◽

Marvin J Meyers ◽

Michael P. Rettig ◽

Ezhilarasi Chendamarai ◽

...

Keyword(s):

Stem Cell ◽

Board Of Directors ◽

Hematopoietic Stem Cell ◽

Research Funding ◽

Patent Application ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Hematopoietic Stem Cell Mobilization ◽

Equity Ownership ◽

Cell Mobilization

Background: Hematopoietic stem cell (HSC) transplant is an essential treatment for a variety of blood disorders and malignancies. A key step in this procedure is the mobilization of donor stem cells. The most commonly used regimen for donor mobilization is a 5-day course of G-CSF. The length of this regimen coupled with the associated side effects emphasizes a need for superior alternatives. In recent years, there has been a growing understanding of mechanisms governing stem cell retention within the bone marrow niche. This has led to the development of new mobilization drugs that specifically target these processes. Two examples of previously described drugs that target mechanisms of stem cell retention are Plerixafor (a CXCR4 inhibitor already in clinical use), and truncated Gro-Beta (tGroβ; a CXCR2 agonist). Another potential target for inducing mobilization is disruption of the interaction between the VLA-4 integrin and its ligand VCAM-1. In this study, we evaluate the efficacy of novel VLA-4 inhibitors (VLA4i) alone and in combination with Plerixafor and/or tGroβ for the purposes of hematopoietic stem cell mobilization. Methods: We synthesized over 15 novel VLA-4 inhibitor molecules and tested their potency using soluble VCAM-1 binding assays. The 5 inhibitors determined to be most potent were then tested in vivo in DBA mice for their ability to mobilize HSCs alone and in combination with tGroβ and/or Plerixafor (n=5). HSC mobilization was measured in wild-type and splenectomized mice via flow cytometry to quantify the proportion of LSK (Lineage- Sca+ cKit+) cells as well as via Colony Forming Unit (CFU) assays. For competitive transplant, mobilized CD45.1+ BALB/c mouse blood (10 uL) was injected into lethally irradiated CD45.2+ BALB/c recipients alongside 2.5x105 CD45.2+ BALB/c bone marrow cells (n=10 / cohort). HSC engraftment was monitored monthly via flow cytometry for ratio of 45.1+ vs. 45.2+ cells in peripheral blood. Results: Firetagrast and BIO5192 are previously characterized VLA4i that have been administered to humans for indications unrelated to HSC mobilization. Our best VLA4i to date, LGB-2019, exhibited similar potency as BIO5192 in preventing the binding of sVCAM-1 to VLA-4 (IC50: 1.7nM) and was >200-fold more potent than firategrast. LGB-2019 showed increased aqueous solubility and mobilized 1.5-fold more murine LSK cells for a longer time period (peak HSC mobilization maintained for 4 hours) than BIO5192 when administered alone. Simultaneous injection of C57BL/6 mice with LGB-2019 (VLA4i), Plerixafor (CXCR4i) and tGro-β (CXCR2a) resulted in a synergistic increase in circulating CFUs (Fig. 1A; 9.8 x 103 CFUs/mL) and LSKs (Fig. 1B; 12.8 LSKs/uL) at 4 hours post-injection. In contrast, 5 days of G-CSF treatment mobilized approximately 3-fold and 8-fold less CFUs and LSKs, respectively (Fig. 1A-B). We saw no significant difference in mobilization for splenectomized vs. wildtype mice (23.4 x 103 CFUs/mL vs. 23.0 x 103 CFUs/mL) when mobilizing DBA/2 mice via VLA4i+CXCR4i+CXCR2a. Three months after competitive transplantation, blood obtained from BALB/c mice mobilized with the triple combination engrafted significantly better than blood obtained from mice treated with G-CSF or the dual combinations (Fig. 1C). Summary: New insights about the stem cell niche have allowed for the development of targeted drugs for the purposes of mobilization. Here, we show that a novel VLA-4 receptor inhibitor in combination with two other known mobilizers induces mobilization of hematopoietic stem and progenitor cells (CFU/LSK) at levels superior to the standard of care G-CSF and in a dramatically shortened time frame. Mouse transplant data also show superior engraftment in lethally irradiated recipients when using the triple cocktail regimen compared to the G-CSF mobilized graft. Secondary transplants are ongoing and will provide a more complete picture of primitive HSC mobilization and serial engraftment properties of the cells. Disclosures Rettig: WashU: Patents & Royalties: Patent Application 16/401,950. Karpova:WashU: Patents & Royalties: Patent Application 16/401,950. Ruminski:WahU: Patents & Royalties: Patent Application 16/401,950. Morrow:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. DiPersio:Cellworks Group, Inc.: Membership on an entity's Board of Directors or advisory committees; RiverVest Venture Partners Arch Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Magenta Therapeutics: Equity Ownership; Incyte: Consultancy, Research Funding; Bioline Rx: Research Funding, Speakers Bureau; Macrogenics: Research Funding, Speakers Bureau; Karyopharm Therapeutics: Consultancy; Celgene: Consultancy; Amphivena Therapeutics: Consultancy, Research Funding; WUGEN: Equity Ownership, Patents & Royalties, Research Funding; NeoImmune Tech: Research Funding.

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Phase 2 Study Of Bendamustine, Bortezomib (Velcade) and Prednisone (BVP) For Newly Diagnosed Multiple Myeloma (MM)

Blood ◽

10.1182/blood.v122.21.2155.2155 ◽

2013 ◽

Vol 122 (21) ◽

pp. 2155-2155 ◽

Cited By ~ 2

Author(s):

Maria-Victoria Mateos ◽

Albert Oriol ◽

Laura Rosiñol ◽

Felipe de Arriba ◽

Jesús Martín ◽

...

Keyword(s):

Stem Cell ◽

High Risk ◽

Board Of Directors ◽

Research Funding ◽

Response Rates ◽

Newly Diagnosed ◽

Advisory Committees ◽

Cd34 Cells ◽

Stem Cell Collection ◽

Poor Mobilizers

Abstract Background Bortezomib-based combinations, including alkylating agents (VMP or CyBorD) or immunomodulatory drugs (VTD or RVD) have been established as regimens widely used in newly diagnosed MM patients. Bendamustine is a bifunctional alkylating agent effective in relapsed and/or refractory MM patients, and approved in Europe in combination with prednisone for elderly newly diagnosed MM. Since bendamustine may be more efficient than other alkylators, an attractive possibility would be to explore it in combination with bortezomib and prednisone (BVP) in newly diagnosed MM patients both transplant and non transplant candidates. Patients and Methods 60 newly diagnosed MM patients were included in the trial. The first cycle consisted on bendamustine at 90 mg/m2 given IV on days 1 and 4, in combination with bortezomib at 1,3 mg/m2 given IV on days 1, 4, 8, 11, 22, 25, 29 and 32 and prednisone at 60 mg/m2 given PO on days 1 to 4. In the following cycles, bendamustine was given on days 1 and 8, and bortezomib on days 1, 8, 15 and 22 (weekly schedule), and prednisone as it was previously described. Patients younger than 65 years proceeded to peripheral blood stem cell collection (PBSC) using growth factors alone after 4 cycles; HDT-ASCT was performed after 6 cycles. Patients older than 65 years received up to nine 28-day cycles. Results Between May 2011 and July 2012 enrollment was completed (60 pts). Median age was 61 years (range 38-82; 18 pts ≥65), 67% had ISS stage II/III, and 67% had unfavorable cytogenetics: t(4;14), t(14;16), del 17p or 1q gains by FISH. After a median of 6 cycles (2-9), 75% of patients achieved at least PR, including 16% of sCR, 9% CR and 28% of VGPR. Although the differences were not statistically significant, there was a trend to higher CR rate in the group of patients <65 years (31%) compared with elderly patients (11%). No differences were observed in overall response rates and CR rates in patients with standard and high risk cytogenetic abnormalities. Forty patients proceeded to stem cell collection after a median of 4 cycles of BVP. Upon using G-CSF alone, 14 pts (35%) failed to collect a minimun of 2 x 106 CD34+ cells/Kg. An ammendment was done and plerixafor was recomended for poor mobilizers (peripheral CD34 cell count inferior to 10/μL on day 4); all patients but 2 achieved, with G-CSF plus plerixafor, the minimum of CD34+ cells required to proceed to ASCT. These 2 patients successfully collected CD34+ cells using chemotherapy plus G-CSF and plerixafor. Of the 31 patients who received HDT-ASCT, sCR and CR rate before transplant was 18% and 13%, respectively, upgrading up to 39% of sCR and 13% CR after transplant. 7 pts (22%) achieved immunophenotypic CR. After a median f/u of 12 months (5-25), 8 pts have progressed, resulting in a 15-m TTP of 85%. Concerning OS, 89% of patients remained alive at 15 months. None of patients achieving sCR and CR have progressed and all of them are alive at 15 months. Regarding cytogenetic abnormalities, although there were not significant differences, one patient progressed in standard risk group and five in the high risk subgroup resulting in a 15 m-TTP of 93% vs 85%. No significant differences have been observed in terms of 15 m-OS between standard and high risk cytogenetic subgroup (100% vs 92%, respectively). As far as toxicity is concerned, hematologic toxicities included: G3/4 anemia (11%), neutropenia (23%), and thrombocytopenia (14%). The most common G3/4 non-hematologic toxicities were: asthenia (10%), infections (9%), and peripheral neuropathy (4%). Conclusions In patients candidates to HDT-ASCT, response rates obtained before and after transplant are comparable to other three drug bortezomib-based combinations, such as VTD or CyBorD. However, growth factors alone for stem cell collection after four BVP cycles as induction resulted in a 35% of poor mobilizers who were rescued with plerixafor. In the elderly population, although the number of patients included was small, BVP seems not superior to VMP in response rates. Disclosures: Mateos: Janssen, Mundipharma: Honoraria. Off Label Use: bendamustine plus bortezomib and prednisone is not an approved combination for first line of therapy. Oriol:Celgene: Consultancy. Ocio:Onyx: Consultancy, Research Funding; Novartis: Consultancy; Array Biopharma: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy; Celgene: Consultancy, Research Funding. Alegre:Celgene: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity’s Board of Directors or advisory committees, Research Funding. Bladé:Janssen, Mundipharma: Honoraria. San Miguel:Janssen, Mundipharma: Membership on an entity’s Board of Directors or advisory committees.

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Impact of ABO Mismatch on Outcomes of Allogeneic Hematopoietic Stem Cell Recipients: 30 Years of Experience with 1016 Patients

Blood ◽

10.1182/blood-2018-99-118314 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 3472-3472 ◽

Cited By ~ 1

Author(s):

Erden Atilla ◽

Pervin Topcuoglu ◽

Erman Akkus ◽

Pinar Ataca Atilla ◽

Sinem Civriz Bozdag ◽

...

Keyword(s):

Stem Cell ◽

Board Of Directors ◽

Hematopoietic Stem Cell ◽

Research Funding ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Host Disease ◽

Graft Vs Host Disease ◽

Engraftment Failure ◽

Support Research

Abstract Introduction: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is widely used to treat malignant and non-malignant hematological diseases. The impact of ABO mismatch on outcome following transplantation remains controversial. In this study, our aim is to define effects of ABO mismatch on engraftment, graft vs host disease, relapse free survival (RFS) and overall survival (OS) in patients who underwent allo-HSCT. Patients and Methods: Between 1988 and 2016, we retrospectively identified 1016 patients who underwent allo-HSCT at Ankara University School of Medicine, Department of Hematology. Chi-square and Fisher's exact tests were used where appropriate in comparison. Cox regression model and Kaplan Meier curves were applied for survival analysis. P<0.05 was considered as statistically significant. Results: The median follow-up period was 34.7 months (range, 0.2-229). In our cohort, there were 420 (41.3%) ABO-mismatched transplants occurred including 167 (16.4%) major, 197 (19.4%) minor and 55 (5.4%) bidirectional mismatches. The pre-transplant characteristics of patients are summarized in table. Allo-HSCTs from unrelated donors and peripheral blood grafts were detected higher in ABO mismatched patients vs ABO matched patients (28% vs 11%, P<0.0001; 78% vs 67%, P<0.0001). The engraftment failure was higher in ABO mismatch group compared to ABO matched group (67 (16%) vs 70 (11%), P=0.05). Neutrophil and platelet engraftment rates were not statistically different in major, minor or bidirectional ABO mismatched vs matched donors. The acute graft vs host disease (GVHD) and chronic GVHD incidences did not alter in patients with ABO match and mismatch (44% vs 45%, P=0.78; 41% vs 39%,P=0.81). In ABO-mismatched group, hemolysis after infusion of graft occurred in 50 patients (12%) whereas during engraftment in 35 patients (8%). Although not statistically significant, hemolysis were occurred higher in major ABO mismatch. Plasma exchanges were performed in 18 patients in the major ABO mismatched group due to high anti-donor type isoagglutinin titers (≥1/128). Pure red cell aplasia was diagnosed in 5 (3%) major ABO mismatched patients. Major ABO mismatch (HR:1.46, 95% Cl:1.06-2.03;P=0.022) was found to be related with lower RFS and OS (HR:1.31, 95% Cl:1.06-1.62;P=0.013). 3-year OS and 1-year RFS were lower with major ABO mismatch (38% vs 47%, P=0.02; 15% vs 24%; P=0.02) (Figure). Conclusion: Engraftment failure was detected higher in patients with ABO mismatch as well as major ABO mismatch was related with lower RFS and OS although the cohort is heterogeneous. Close monitoring and early treatment strategies for expectable complications would reduce the number fatal events by ABO mismatched allo-HSCT. Disclosures Civriz Bozdag: NOVARTIS: Consultancy; MSD: Research Funding; TAKEDA: Consultancy. Özcan:Abbvie: Other: Travel payment; Bayer: Research Funding; MSD: Other: travel support, Research Funding; Roche: Honoraria, Research Funding; Janssen: Other: Travel Support, Research Funding; BMS: Honoraria; Novartis: Research Funding; Jazz: Other; Jazz: Other: Travel support; Archigen: Research Funding; Celgene: Other: Travel support, Research Funding; MSD: Research Funding; Takeda: Honoraria, Other: Travel payment, Research Funding. Beksac:Deva: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Ilhan:Roche: Speakers Bureau; BMS: Speakers Bureau; Celgene: Speakers Bureau; Alexion: Speakers Bureau.

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Acceptable Toxicity and Good Hematological and Renal Responses after Autologous Hematopoietic Stem Cell Transplantation in Multiple Myeloma Patients with Renal Insufficiency at Transplant: A Prospective SFGM-TC Observational Study

Blood ◽

10.1182/blood-2020-140713 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 38-39 ◽

Cited By ~ 1

Author(s):

Laurent Garderet ◽

Hafida Ouldjeriouat ◽

Mohamed-Amine Bekadja ◽

Elisabeth Daguenet ◽

Laure Vincent ◽

...

Keyword(s):

Multiple Myeloma ◽

Renal Function ◽

Stem Cell ◽

Hematopoietic Stem Cell Transplantation ◽

Board Of Directors ◽

Research Funding ◽

Median Number ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Cd34 Cells

Background: High dose melphalan (HDM) followed by autologous hematopoietic stem cell transplantation (ASCT) is widely used in multiple myeloma (MM) patients as upfront and salvage therapy. However, the safety and efficacy of ASCT in patients with renal insufficiency (RI) is controversial, which have led to an inconsistent arbitrary cut-off for creatinine clearance (CrCl) for performing ASCT. Here we analyzed prospectively the outcomes of MM patients with severe RI who underwent ASCT. Methods: We enrolled prospectively 50 newly diagnosed MM patients who had a serum CrCl of <40 mL/min at the time of ASCT and an age of up to 65 years. They all received bortezomib-based induction therapy and had achieved at least a partial response before proceeding to ASCT. The recommended dose of melphalan was 140 mg/m2 and it was advised to infuse at least 3 x106/kg autologous CD34+ cells. Consolidation/maintenance post-ASCT was according to the physician's choice. The primary endpoint was transplant related mortality. Results: The patients characteristics at enrollment are given in Table 1. We focused on 44 patients who were beyond 3 months post-ASCT. Light chain MM was frequent (12%), 10% had high risk cytogenetics, 36% increased serum LDH and 10% extramedullary disease. Induction chemotherapies included bortezomib plus IMiDs in 25/44 patients with ≥2 lines of chemotherapy in 12/44. The pre-transplant disease status was sCR in =5%, CR in =15%, VGPR in =39%, and PR in =41% of patients. The number of days of cytapheresis was 2 or less in 95% of cases and the median number of CD34+ cells collected was 3.3 x 106 (1.3-9.5). The median time from diagnosis to ASCT was 175 days (103-307). HDM was 140 mg/m2 in 42/44 patients and 200 mg/m2 in 2/44. All, except two, received consolidation post ASCT (34% missing) and 52% had maintenance therapy (all lenalidomide except two receiving bortezomib) and 7% had no maintenance (41% pending). Toxicity: We observed one death during the first 100 days post-ASCT, secondary to a septic shock on day 42. The median time to neutrophil engraftment was 12 days (9-68) and to platelet engraftment 13 days (10-70). Among patients receiving RBC transfusions (75%) and platelet transfusions (84%), the median number of RBC transfusions was 3 (1-6) and that of platelet transfusions was 3 (1-10). Response: Nine patients (70%) achieved dialysis independence from the time of diagnosis: 13 patients were on dialysis at diagnosis, 5 at the time of ASCT and 4 three months post-ASCT. Renal function improved post-ASCT in 34% of patients, 14% moving from a CrCl of <40 mL/min to 60 mL/min and 20% to above 60 mL/min. No patient experienced worsened renal function following ASCT. At 100 days post-ASCT, the hematological response had improved in 49% of patients, from PR to VGPR (18%), from PR to CR/sCR (11%) and from VGPR to CR/sCR (20%). The best response obtained was 5% PR, 34% VGPR, 47% CR and 11% sCR with one patient relapsing. Conclusions: In this preliminary analysis, HDM with ASCT proved to be safe and effective in MM patients with RI at transplant. We observed one death among 44 patients within the first 3 months post-ASCT. A more detailed report of the toxicity will be presented during the meeting along with the survival. Disclosures Vincent: takeda: Membership on an entity's Board of Directors or advisory committees, Other: Congress support; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Congress support; janssen: Membership on an entity's Board of Directors or advisory committees, Other: Congress support. Mohty:Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding, Speakers Bureau; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; Stemline: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Research Funding, Speakers Bureau; GSK: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau. Karlin:AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support; Celgene/Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, personal fees; GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Other: Personal fees; Sanofi: Honoraria; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, personal fees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, personal fees. Morel:Janssen: Honoraria. Rubio:Medac: Consultancy; Gilead: Honoraria; MSD: Honoraria; Novartis: Honoraria; Neovii: Research Funding.

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JMML Fetal Identity Results Either from Retention of a Physiologic Signature or Aberrant Activation of Master Oncofetal Regulators

Blood ◽

10.1182/blood-2020-136367 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 4-5

Author(s):

Marion Strullu ◽

Aurélie Caye-Eude ◽

Loïc Maillard ◽

Chloé Arfeuille ◽

Elodie Lainey ◽

...

Keyword(s):

Gene Expression ◽

Stem Cell ◽

Board Of Directors ◽

Hematopoietic Stem Cell ◽

Hierarchical Clustering ◽

Research Funding ◽

Gene Set Enrichment Analysis ◽

Hematopoietic Progenitors ◽

Advisory Committees ◽

Hematopoietic Stem

Objectives: Juvenile myelomonocytic leukemia (JMML) is a rare but aggressive myeloproliferative/myelodysplastic neoplasm affecting infants and young children. The narrow age-window of onset suggests that a prenatal environment is needed for JMML oncogenesis. In search of a transcriptional reminiscence of embryo-fetal characteristics that would confirm this hypothesis, we investigated how the gene expression profile of JMML hematopoietic progenitors compared to their healthy counterpart isolated at different stages of ontogeny. Methods: Hematopoietic stem cell and progenitor cell (HSPC) fractions of JMML (n=16), bone marrow (BM) of healthy children (n=7), fetal liver (FL; n=3) and fetal BM (FBM; n=2) were phenotyped and sorted using signatures validated in the fetal and adult BM (Notta et al, Science 2011). RNAseq was performed using the TruSeq® Stranded Total RNASample preparation kit. Unsupervised hierarchical clustering analysis was done with the Bioconductor edgeR package. Differentially expressed genes were identified with the Bioconductor limma package. Results: To eliminate the impact of variations in the HSPC distribution, the JMML transcriptome was assessed on FACS-sorted common myeloid progenitor (CMP), granulocyte-monocyte progenitor (GMP) and megakaryocyte-erythroid progenitor (MEP) cell fractions from 16 JMML and compared to healthy counterparts at different stages of ontogeny (FL, FBM, age-matched children BM). Unsupervised hierarchical clustering separated the samples into 4 groups (C1-4), primarily according to ontogeny, with 14/15 embryo-fetal fractions in C1 and all healthy post-natal progenitors in C2 (CMP, MEP) or C3 (GMP). Most JMML fractions clustered either with the prenatal fractions (C1; 17/47 fractions from 8/16 patients) or in a separate group containing no healthy sample (C4; 23/47 samples from 10/16 patients). Two groups were defined accordingly: one with JMML resembling embryo-fetal samples ('Fetal-JMML'; n=6/16), and a JMML-specific group ('Onco-JMML'; 8/16). Patients with Onco-JMML tended to be older, with a more severe presentation and elevated fetal hemoglobin levels. All PTPN11-mutated JMML were in this group whereas 5/6 Fetal-JMML had NRAS or KRAS mutations. Analysis of differential gene expression between Fetal and Onco-JMML highlighted 344 up-regulated genes versus 19 up-regulated genes in Onco-JMML. Surprisingly, LIN28B and WT1, both known to activate fetal pathways, were the most up-regulated genes in Onco-JMML. These key transcription factors were deregulated as early as the hematopoietic stem cell (HSC) compartment. Gene Set Enrichment Analysis (GSEA) confirmed enrichment in LIN28B and WT1-related signatures and showed enrichment in an AML signature in Onco-JMML. On the other hand, Fetal-JMML showed striking overexpression of monocytic /dendritic cell markers and inflammasome and innate immunity components. GSEA confirmed the strong monocyte identity of Fetal-JMML progenitors compared to onco-JMML or healthy postnatal progenitors. Part of the monocytic markers 'aberrantly' expressed in JMML progenitors was expressed in healthy fetal progenitors. Analysis of the HSC and multipotent progenitor (MPP) fractions showed that up regulation of monocytic markers was limited to the JMML progeny compartments. As we were able to confirm the transcriptional and functional identity of the sorted progenitors, these data suggest an early monocytic priming in these JMML progenitors, reminiscent of the monocyte-biased myelopoiesis characterizing physiologic fetal hematopoiesis. Conclusion: Our findings give a striking example of how ontogeny-related features are involved in childhood oncogenesis. They highlight a strong but complex link beween JMML and development, with a fetal identity resulting either from retention of a physiologic fetal monocytic signature or from aberrant (re)activation of master oncofetal regulators. Intriguingly, although LIN28B is thought to reprogram hematopoietic progenitors into a fetal-like state, its activation does not lead to an overall fetal profile in JMML, suggesting a regulatory mechanism distinct from that of physiological development. These two ontogeny-based signatures are likely to uncover the biology underlying previous classifiers based on AML-like profile or DNA methylation and suggest that a subset of JMML patient may benefit from immunomodulating therapies. Disclosures Dalle: Bellicum: Consultancy, Honoraria; bluebird bio: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi-Genzyme: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Medac: Consultancy, Honoraria; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria; AbbVie Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Orchard: Consultancy, Honoraria; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees. Baruchel:Jazz Pharmaceuticals: Consultancy, Honoraria; Celgene Corporation: Consultancy, Honoraria; Astra Zeneca: Consultancy; Servier: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Shire: Research Funding; Bellicum: Consultancy.

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