ALBERT

Description: The concept of suppressing dendritic cells (DCs) to prevent graft-versus-host disease (GvHD) following allogeneic hematopoietic stem cell transplantation (HSCT) has been rejuvenated since the introduction of proteasome inhibitors into clinical practice. Although early post-transplant administration of proteasome inhibitors ameliorates GvHD, delayed administration has been associated with alloreactivity-dependent gastrointestinal toxicity. This phenomenon is associated with a surge in interleukin-1β (IL-1β) and acceleration in donor T cell expansion. To address this issue, we sought to investigate whether in vivo depletion of donor T cells by concomitant administration of post-transplant cyclophosphamide (C) could overcome this phenomenon. Ten-week old BALB/c mice were irradiated (10 grays in two fractions) on day -1 and transplanted with 5x106 BM cells from C57BL6 mice. GvH inocula consisted of 5x106 splenocytes from C57BL6 (some post-CFSE labeling) or B6;FVB-PtprcaTg(CAG-Luc,-GFP)L2G85Chco Thy1a/J (ubiquitously transgenic for firefly luciferase for bioluminescence imaging (BLI). All mice were purchased from Jackson Laboratory and kept in a pathogen-free environment. Mice were untreated or received ixazomib (Z) (30μg, subcutaneously) on days -1, +2, and +5, C (1 mg intraperitoneally) on day +2, or both Z and C according to the same schedule. Mice were monitored for weight, GvHD score, and survival or sacrificed on day +6 for cytokine measurement and splenic cell counts. For BLI, mice receiving transgenic splenocytes were injected with 150mg/kg of D-Luciferin intraperitoneally and imaged 25 minutes later. GvHD worsening and sudden death occurred in a fraction of mice receiving Z following day +5 injection. The phenomenon was completely prevented by the addition of C. Overall, the group receiving both Z and C had significantly improved weight, GvHD score, and survival when compared to the mice left untreated or receiving either drug alone (figure 1). The addition of C to Z prevented IL-1β increase, was associated with suppression of tumor necrosis factor α (TNFα), and resulted in a profound depletion of splenic total and donor CD4+ cells. Furthermore, proliferating cells (CFSE low) were preferentially depleted as opposed to quiescent cells (CFSE high). BLI imaging showed an increase in signal intensity shortly after the administration of Z on day +5. On the other hand, the mice receiving C in addition to Z exhibited significantly lower donor T cell proliferation when compared to the other groups (figure 2). These findings suggest that C can prevent the phenomenon of GvHD acceleration associated with the extended administration of proteasome inhibitors, suppress cytokine production, and effectively reduce splenic total and donor CD4+ cell expansion with preferential depletion of proliferating as opposed to quiescent cells. The combination of Z and C seems a promising duplet for the prevention of GvHD. When Z is administered late following allogeneic HSCT for the prevention of disease relapse, the addition of C should be considered in order to avoid any unwanted aggravation of alloreactivity. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures No relevant conflicts of interest to declare.

Description: High-dose melphalan (M) followed by autologous hematopoietic stem cell transplantation (AHSCT) remains the standard treatment for multiple myeloma in eligible patients, even in the era of novel agents. However, the majority of patients ultimately relapse and succumb to their disease. Several studies have explored integrating novel agents into the conditioning regimen prior to AHSCT in order to improve complete remission rates and ultimately overall survival. We aimed to assess the feasibility of adding bendamustine (B) and carfilzomib (C) to melphalan (BCM) and performed a phase I dose escalation study. Thirteen patients were enrolled between June 2014 and June 2016. All patients received C at a fixed dose (20 mg/m2) on days (d) -29, -28, -22, -21, -15, -14. The conditioning regimen and doses administered for each cohort were as described in the table below. Due to excessive toxicity, the study was amended after the first 6 patients. Per oversight of a data safety monitoring board, the dose of M was reduced to 140 mg/m2 and C dose on d +6 was omitted. Median age was 58 years (39-68). There were 8 males and 5 females. Performance status was ≥ 80% in all patients. Per the International Staging System (ISS), 3 patients had stage I disease, 5 had stage II, 4 had stage III, and 1 had unknown staging. Three patients had high-risk cytogenetics: 2 with t(4;14) and 1 with deletion 17p. Three patients had received prior AHSCT. Disease status prior to study treatment was stable disease (SD) (n=2), partial response (PR) (n=8), or very good partial response (VGPR) (n=3). Median CD34+ cell dose was 3.24x106/kg (2.23-6.92x106). Median follow-up was 14.2 months (1-24.5). Median time to neutrophil engraftment was 12 d (11-15). One patient died before achieving platelet engraftment. For the remaining patients, median time to platelet engraftment was 16 d (12-20). Non-hematologic toxicities included grade 3 acute mucositis (n=1), lower GI complications (n=6), electrolyte disturbances (n=6), transaminase elevation (n=1) renal insufficiency (n=1), pulmonary edema (n=1), prolonged QTc (n=1), atrial fibrillation (n=1), and elevated troponin (n=1) and grade 4 acute sepsis (n=2), resulting in 1 death in cohort 2 on d +44. Seven patients went on to receive maintenance therapy: 3 with bortezomib, 3 with lenalidomide, and 1 with lenalidomide, dexamethasone, and C. Post-transplant disease status was assessed per protocol by SPEP, SPIF, and serum free light chains and light chain ratio. Nine patients were evaluable on d +100. One patient had SD, 6 had VGPR, and 2 had complete response (CR). Six out of 7 (86%) evaluable patients on d +365 remain disease progression-free. In summary, BCM conditioning prior to AHSCT at the doses described in cohort 3b seems feasible with manageable toxicities. Five additional patients are being enrolled at the same dose level. Table Table. Disclosures No relevant conflicts of interest to declare.

Description: CYAD-01 cells are engineered T-cells expressing a chimeric antigen receptor (CAR) based on the natural full-length human natural killer group 2D (NKG2D) receptor fused to the intracellular domain of CD3ζ. NKG2D binds to 8 ligands (MICA, MICAB, and ULBP1-6) over-expressed by a large variety of malignancies, including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Phase I DEPLETHINK study (NCT03466320) evaluates the safety and preliminary efficacy of a single CYAD-01 infusion (inf.) after lymphodepletion with cyclophosphamide and fludarabine in patients with relapsed or refractory (r/r) AML and MDS. A second cycle of 3 CYAD-01 infusions without preconditioning could be administered in absence of progressive disease (PD) following the 1st infusion. Three dose-levels (DLs; 1x108, 3x108 and 1x109 cells/inf.) are evaluated in the dose escalation segment. The first DL is also evaluated at two different intervals between preconditioning and CYAD-01 infusion (T7: seven days interval; T3: three days interval) in order to mitigate for any potential increased toxicity due to the administration of lymphodepletion. As of end of July 2019, 6 patients (4 AML and 2 MDS) were enrolled in the first 2 cohorts which evaluated DL1 (1x108 cells/inf. at T3 or T7) and 3 patients (3 AML) were enrolled in the cohort 3 evaluating DL2 (3x108 cells/inf. at T3). The blasts in the bone marrow of 8 out of 9 patients ranged between 3% and 48% at baseline. Of the 6 patients treated at DL1 (with lymphodepletion administered up to 7 or 3 days before first CYAD-01 infusion), 3 patients experienced grade (G) 1 toxicity (cytokine release syndrome or CRS and diarrhea), or G2 CRS (uncleaned database). The patient with G2 CRS following the first infusion also experienced G4 CRS and G3 CAR T-cell-related encephalopathy syndrome (CRES) during the second inf. at 3x109 cells/inf. One other patient experienced G1 CRS during the second cycle. At DL2, only 1 patient experienced G1 related AEs (diarrhea and CRS) after the first CYAD-01 infusion. Another patient experienced G3 CRS during the second cycle. All patients recovered with treatment including tocilizumab and, when indicated, steroids. At DL1, two out of 5 evaluable patients reached a stable disease (SD) at day (d) 36, allowing the initiation of the 2nd cycle. At DL2, one patient out of 3 reached SD. The DEPLETHINK study is currently enrolling at DL3 (T3). Preliminary correlative studies show that the area under the curve at d36 (AUC D1-D36) after a single infusion of CYAD-01 with prior lymphodepletion is better than without preconditioning. Furthermore, the T3 interval between the preconditioning and CYAD-01 provides better engraftment than the T7 interval. In conclusion, to date, the results demonstrate the safety and tolerability for CYAD-01 doses 1x108 and 3x108 cells/infusion with a prior lymphodepletion in patients with r/r AML and MDS. The T3 interval was therefore chosen for further CYAD-01 evaluations. The improved persistence of CYAD-01 with lymphodepletion, in particular 3 days before infusion, could lead to improved clinical responses. The study is ongoing and further data will be provided at the meeting. Disclosures Al-Homsi: Celyad: Membership on an entity's Board of Directors or advisory committees. Abdul-Hay:Takeda: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Pollyea:Diachii Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celyad: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Forty-Seven: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees. Lequertier:Celyad: Employment. Alcantar-Orozco:Celyad: Employment. Borghese:Celyad: Employment. Lonez:Celyad: Employment. Braun:Celyad: Employment. Renard:Celyad: Employment. Flament:Celyad: Employment.

Description: Background: Targeting T cells alone has yielded limited success in the prevention of graft-versus-host disease (GvHD) following allogeneic blood and marrow transplantation (BMT). Dendritic cells (DCs) play a central role in alloreactivity and therefore represent a suitable target. Proteasome inhibitors (PI), with their ability to inhibit the function and maturation of DC, have prompted investigators to examine their potential role in the prevention of GvHD. The investigational PI, ixazomib (IXZ), dissociates rapidly from 20S and is therefore truly reversible. It is also orally bioavailable. Our aim in this study was to explore its effect on healthy volunteer peripheral blood dendritic and T cells and in a pre-clinical GvHD mouse model. Methods: To characterize the effects of IXZ on healthy volunteer peripheral blood DCs, DCs were isolated using EasySep Pan-DC Pre-Enrichment Cocktail with purity over 90% (STEMCELL Technologies). DCs were then treated with IXZ at different concentrations (10-40nM) for 4 hrs and then stimulated with lipopolysaccharide (LPS) for 16 hrs. After this treatment, DCs were surface stained with antibodies against maturation markers and analyzed by flow cytometry. DC survival was evaluated with 7AAD staining and FACS analysis. To assess the effect of IXZ on the production of pro-inflammatory cytokines, DCs were incubated with IXZ at increasing concentration before or after the addition of LPS. Total pro-inflammatory cytokines in the supernatant of tissue culture were measured using EMD Millipore cytokine arrays. Standard mixed lymphocyte reaction and T cell proliferation assays were used to evaluate T cell function. At a minimum, all experiments were done in triplicate. Unpaired t test was used for statistical analysis. A p-value 〈 0.05 was considered significant. The B6 → BALB/c pre-clinical GvHD model was adopted to evaluate the effect of IXZ on GvHD development. Mice were transplanted in 3 groups. Group 1 received a lethal dose of total body irradiation (TBI), donor bone marrow (BM) cells, and IXZ, group 2 received TBI, donor BM cells donor splenocytes, and a vehicle, and group 3 received TBI, donor BM cells, donor splenocytes, and IXZ. The dose of BM cells and splenocytes was 5 X 106 each. IXZ was given at 1.5 mg/kg subcutaneously. Two dosing schedules were tested in 2 separate experiments: day-1 and +2 or day +1 and +4. Results: IXZ inhibited the expression of 6 DC maturation markers including CD40, CD54, CD80, CD83, CD86 and CD197 (CCR-7). The inhibition started at a concentration of 10nM and was dose-related. IXZ also decreased the percentage of total DCs simultaneously expressing multiple markers. DCs viability remained unchanged in comparison to control at a concentration of 10nM and dropped to 68% and 43%, on average with concentrations of 20nM and 40nM, respectively. IXZ significantly decreased DC production of IL-6, IL-12, and IL-23 starting at the concentration of 20nM. IL-1β was decreased at the concentration of 40 nM. Importantly, there was no significant change in the cytokine production by DCs when IXZ was added 4 hrs after LPS except for IL-1β which increased at 30nM. Starting at the concentration of 10nM, IXZ dose-dependently inhibited T cell proliferation. At 40nM IXZ abolished T cells. In our in vivo study IXZ improved GvHD scores on days +7 and +11 in group 3 in comparison to group 2 when it was given on days -1 and +2. Conversely, when IXZ was given on day +1 and +4, group 3 mice had higher scores of GvHD and worse survival outcomes when compared to group 2. There was no noticeable drug toxicity in group 1 mice. Conclusion: In summary: 1) IXZ inhibits DC maturation with relative preservation of cell viability and inhibits pro-inflammatory cytokine production in DCs when added before LPS stimulation; 2) IXZ inhibits T-cell proliferation; 3) IXZ affects GvHD development in a schedule-dependent fashion with early administration improving and late administration worsening GvHD. Additional analysis of tissue and serum samples is in progress. These results provide background for careful design of clinical trials using IXZ for the prevention of GvHD. Disclosures Al-Homsi: Millennium Pharmaceuticals: Research Funding.

Description: Graft versus host disease (GvHD) remains a major barrier to the progress of blood and marrow transplantation and limits its wide applicability. Standard prophylactic regimens essentially targeting T lymphocytes are partially effective and burdensome. Cyclophosphamide (Cy) administered post-transplant selectively deletes alloreactive proliferating T cells, promotes expansion of regulatory T cells, and induces long-lasting depletion of intrathymic host-reactive T cells. It is an attractive option for prevention of GvHD and has already been used alone in matched related and unrelated donor transplants. However, despite a low incidence of chronic GvHD, acute GvHD still occurs in 50% of cases and is grade III-IV in 15% of cases. Dendritic cells (DCs) play a pivotal role in the early phase of GvHD. Proteasome inhibitors such as bortezomib (Bor) have a number of immunomodulatory effects including inhibition of DCs maturation and function. We therefore initiated a phase I feasibility study combining post-transplant Cy & Bor. Twelve patients with hematological malignancies undergoing peripheral blood allogeneic transplantation from matched related (n=6) or unrelated (n=6) donors have so far been enrolled. Disease risk index (DRI) was low in 4, intermediate in 3 and high or very high in 5. The conditioning regimen combined fludarabine and busulfan (total 6.4 mg/kg). Patients receiving graft from unrelated donors also received rabbit anti-thymocyte globulin at 5-8 mg/kg. The dose of Bor was escalated in standard fashion. Three patients in each of cohorts 1 and 2 received 0.7 and 1 mg/m2 respectively. The subsequent 6 patients received 1.3 mg/m2. All patients received 2 IV doses, 6 hours after graft infusion and 72 hours thereafter. Cy was given at 50 mg/kg IV on days +3 and +4. Steroids were not allowed after day 0. Engraftment was prompt in all patients. Median time to neutrophil engraftment was 15.5 days (range 14-25). One patient failed to meet criteria for platelet engraftment. The patient had acyclovir-resistant herpes genitalis and CMV reactivation requiring protracted therapy with foscarnet. The remaining patients had a median time to platelet recovery of 28 days (range 15-109). All patients achieved full chimerism by day 20 except one who had residual CLL and did not reach full chimerism until day +119. No patient developed secondary graft failure. Two treatment-related deaths occurred on day +150 due to RSV pneumonitis and on day +200 due to acute sepsis. One patient with recurrent multiple myeloma after autologous transplantation died due to progressive disease. No other Common Toxicity Criteria grade 3 or 4 occurred in any patient. With a median follow-up of 21 months (range 1-27), the overall 2-year predicted disease free survival and overall survival were both 60%. Incidence of acute GvHD in 11 patients with follow-up 〉 100 days, was 64%: grade I 55%, grade II 9%, and grade III-IV 0%. GI and liver acute GvHD were not encountered. Only 4 patients received systemic steroids for acute GvHD; only one required 〉 20 mg/day of prednisone. One patient developed chronic GvHD of the liver (biopsy-proven). Another patient developed poor appetite and weight loss on day +138. Endoscopy showed gastric ulceration. No biopsy was obtained. Neither calcineurin nor m-TOR inhibitors were ever used. Two patients developed extensive HSV-genito-rectal ulcers; one had prior history of recurrent flares. When institutional guidelines were changed to start acyclovir at the beginning of conditioning as opposed to day +5, no other cases was noted. Seven patients developed CMV reactivation and required preemptive therapy only. One patient developed BK virus-induced hematuria and 1 patient developed CNS toxoplasmosis. In summary, the calcineurin and m-TOR inhibitor-free post-transplant Cy & Bor combination for GvHD prophylaxis is feasible and safe. Although the small number of patients prevents any definite conclusion, the absence of incidence of grade III-IV acute GvHD and the sparing of the GI tract and liver are promising. Furthermore, the completion of GvHD prophylaxis by day +4 without the need for close renal and drug level monitoring are both practical and appealing. Updated results with longer follow-up will be reported at the meeting. A confirmatory phase II study is underway. Disclosures Al-Homsi: Millennium Pharmaceuticals: Research Funding. Off Label Use: Bortezomib use for aGvHD prevention.

Description: Background Autologous CAR T-cell therapy targeting the B-cell maturation antigen (BCMA) has shown impressive objective response rates in patients with advanced multiple myeloma (MM). Clinical grade manufacturing of autologous CAR T-cells has limitations including vein-to-vein delivery time delay and potentially sub-optimal immunological capability of T-cells isolated from patients with advanced disease. Allogeneic CAR T-cell products, whereby cells from healthy third-party donors are used to generate an "off-the-shelf" CAR T-cell product, have the potential to overcome some of these issues. To circumvent the primary potential risk of graft-versus-host disease (GvHD) associated with the use of allogeneic T-cells, abrogation of the T-cell receptor (TCR) expression in the CAR T-cells, via gene editing, is being actively pursued. To avoid the potential safety risks and manufacturing challenges associated with gene editing, the allogeneic CYAD-211 CAR T-cell product exploits short hairpin RNA (shRNA) interference technology to down-regulate TCR expression thus avoiding the risk of life-threatening GvHD. Aim The aim is to generate a BCMA-specific allogeneic CAR T-cell product using a non-gene editing approach and study its activity both in vitro and in vivo. CYAD-211 combines a BCMA-specific CAR with a single optimized shRNA targeting the TCR CD3ζ subunit. Downregulation of CD3ζ impairs the TCR expression on the surface of the donor T-cells, preventing their reactivity with the normal host tissue cells and potential GvHD induction. Maintaining all the elements required for the therapy within a single vector (all-in-one vector) provides some significant manufacturing advantages, as a solitary selection step will isolate cells expressing all the desired traits. Results CYAD-211 cells produce high amounts of interferon-gamma (IFN-γ) during in vitro co-cultures with various BCMA-expressing MM cell lines (i.e., RPMI-8226, OPM-2, U266, and KMS-11). Cytotoxicity experiments confirmed that CYAD-211 efficiently kills MM cell lines in a BCMA-specific manner. The anti-tumor efficacy of CYAD-211 was further confirmed in vivo, in xenograft MM models using the RPMI-8226 and KMS-11 cell lines. Preclinical data also showed no demonstrable evidence of GvHD when CYAD-211 was infused in NSG mice confirming efficient inhibition of TCR-induced activation. Following FDA acceptance of the IND application, IMMUNICY-1, a first-in-human, open-label dose-escalation phase I clinical study evaluating the safety and clinical activity of CYAD-211 for the treatment of relapsed or refractory MM patients to at least two prior MM treatment regimens, is scheduled to begin recruitment. IMMUNICY-1 will evaluate three dose-levels of CYAD-211 (3x107, 1x108 and 3x108 cells/infusion) administered as a single infusion after a non-myeloablative conditioning (cyclophosphamide 300 mg/m²/day and fludarabine 30 mg/m²/day, daily for 3 days) according to a classical Fibonacci 3+3 design. Description of the study design and preliminary safety and clinical data from the first cohort will be presented at ASH 2020. Conclusion CYAD-211 is the first generation of non-gene edited allogeneic CAR T-cell product based on shRNA technology. The IMMUNICY-1 clinical study seeks to provide proof of principle that single shRNA-mediated knockdown can generate fully functional allogeneic CAR T-cells in humans without GvHD-inducing potential. We anticipate that subsequent generations of this technology will incorporate multiple shRNA hairpins within a single vector system. This will enable the production of allogeneic CAR T-cells in which multiple genes of interest are modulated simultaneously thereby providing a platform approach that can underpin the future of this therapeutic modality. Figure 1 Disclosures Al-Homsi: Celyad: Membership on an entity's Board of Directors or advisory committees. Brayer:Janssen: Consultancy; Bristol-Myers Squibb, WindMIL Therapeutics: Research Funding; Bristol-Myers Squibb, Janssen, Amgen: Speakers Bureau. Nishihori:Novartis: Other: Research support to institution; Karyopharm: Other: Research support to institution. Sotiropoulou:Celyad Oncology: Current Employment. Twyffels:Celyad Oncology: Current Employment. Bolsee:Celyad Oncology: Current Employment. Braun:Celyad Oncology: Current Employment. Lonez:Celyad Oncology: Current Employment. Gilham:Celyad Oncology: Current Employment. Flament:Celyad Oncology: Current Employment. Lehmann:Celyad Oncology: Current Employment.

Description: Background CYAD-01 is a T-cell product engineered to express a chimeric antigen receptor (CAR) based on the NKG2D receptor (NKG2D CAR) which binds 8 ligands (MICA/B, ULBP1-6) over-expressed by a large variety of malignancies, including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). The phase I THINK study (NCT03018405) evaluated the safety and clinical activity of multiple injections of CYAD-01 infused every 2 weeks, without preconditioning chemotherapy, in 13 relapsed/refractory (r/r) AML and MDS patients. While an encouraging objective response rate according to ELN2017 (AML) or revised IPSS (MDS) and reduction in bone marrow blasts were seen with good safety profile, the responses were short-lived (≤ 3 months - see ASH 2019, poster 3826). To enhance CAR T-cell persistence, we evaluated a weekly dose schedule without preconditioning (THINK study) or the addition of cyclophosphamide and fludarabine (CyFlu) as a preconditioning regimen prior to CAR T-cell infusion (phase I DEPLETHINK study, NCT03466320). Aim To further increase persistence and potency of the T-cell product, optimization of the previously used mAb manufacturing process was performed by shortening the duration of production along with modification of PI3K inhibitor. This optimized manufacturing process (termed "OptimAb") aimed to generate CYAD-01 cells with a higher frequency of early memory T-cells with high cytokine secretion upon activation, as compared to the original "mAb" process. Results As compared to the previous mAb manufacturing process, the OptimAb manufacturing process generates a product that secretes higher levels of IFN-γ upon co-culture with tumor cells and contains a higher frequency of CD62L+ T-cells in vitro, characteristic of an early memory phenotype. In an in vivo aggressive AML (THP-1) model, CYAD-01 OptimAb displayed a strong improvement in long-term anti-tumor activity as compared to the CYAD-01 mAb at the same dose chosen to have a minimal anti-tumor activity (stress-test dose, see figure). Based on these results, both THINK and DEPLETHINK clinical studies were amended to evaluate the OptimAb process. As of August 2020, 5 patients have been treated with multiple infusions of the OptimAb CYAD-01 as standalone treatment at the dose of 3x108 cells/infusion in the small expansion segment of the THINK study. 7 patients were treated with a single infusion of OptimAb CYAD-01 administered after a CyFlu preconditioning in the dose-escalation segment at the doses of 3x108 cells/infusion or 1x109 cells/infusion in the DEPLETHINK study. To date, the results demonstrate the safety and tolerability for CYAD-01 OptimAb with or without a prior lymphodepletion in patients with r/r AML and MDS. Preliminary data of the clinical and pharmacokinetics evaluation of CYAD-01 manufactured with the improved OptimAb process, as compared with the mAb process at the same dose, in two Phase I studies will be provided at the time of presentation. Conclusion/summary The autologous CYAD-01, a first generation NKG2D CAR T-cell product is currently investigated in r/r AML/MDS patients, a difficult to target disease due in part to the absence of truly AML-specific surface antigens, its rapid clinical progression and the absence of disease control by the CyFLu preconditioning. CYAD-01 manufactured using an optimized process, OptimAb, aims to improve CAR T-cell persistence and clinical responses. The data analysis of the same CAR-T product with different manufacturing processes, with or without preconditioning chemotherapy, will provide the medical community with clinical and scientific insights to guide the future of this therapeutic modality. Figure Disclosures Sallman: Agios, Bristol Myers Squibb, Celyad Oncology, Incyte, Intellia Therapeutics, Kite Pharma, Novartis, Syndax: Consultancy; Celgene, Jazz Pharma: Research Funding. Al-Homsi:Celyad: Membership on an entity's Board of Directors or advisory committees. Pollyea:Janssen: Consultancy; 47: Consultancy, Research Funding; Amgen: Consultancy; Genentech: Consultancy; Novartis: Consultancy; Karyopharm: Consultancy; Syndax: Consultancy; Syros: Consultancy; Abbvie: Consultancy, Research Funding; Daiichi Sankyo: Consultancy; Takeda: Consultancy; Pfizer: Consultancy; Celgene/BMS: Consultancy; Agios: Consultancy; Glycomimetics: Other. Wang:Abbvie: Consultancy; Pfizer: Speakers Bureau; Genentech: Consultancy; Stemline: Speakers Bureau; PTC Therapeutics: Consultancy; Macrogenics: Consultancy; Astellas: Consultancy; Bristol Meyers Squibb (Celgene): Consultancy; Jazz Pharmaceuticals: Consultancy. Demoulin:Celyad Oncology: Current Employment. Sotiropoulou:Celyad Oncology: Current Employment. Alcantar-Orozco:Celyad Oncology: Current Employment. Breman:Celyad Oncology: Current Employment. Dheur:Celyad Oncology: Current Employment. Braun:Celyad Oncology: Current Employment. Lonez:Celyad Oncology: Current Employment. Gilham:Celyad Oncology: Current Employment. Flament:Celyad Oncology: Current Employment. Lehmann:Celyad Oncology: Current Employment.