Natural killer (NK) cells are promising platforms for off-the-shelf immunotherapy, yet nonviral precision engineering remains limited by poor HDR efficiency, DNA toxicity, and manufacturing challenges. The aim of this study was to establish a high-yield, nonviral knock-in platform. Through extensive in-depth rational screens, we achieved ∼90% HDR insertion of therapeutic payloads while maintaining 100% postediting recovery. By hijacking endogenous transcriptional programs, we installed genetic circuits into defined genomic loci to tune transgene expression. To enable context-dependent therapeutic responses, we integrated a synthetic positive feedback circuit at the CISH locus, which enhanced NK cell persistence and drove strong expression of anti-CD22/19 dual CAR. A hypoxia-responsive IL-12 circuit gated by the PFKFB4 promoter restored cytotoxicity under environmental stress. Finally, we showed this platform is compatible with GMP manufacturing and supports clinical-scale expansion. These findings provide a scalable framework for programmable, nonviral editing of NK cell effector functions for therapeutic and research applications.

BACKGROUND:Over the past decade, immunotherapeutic strategies-mainly targeting the PD-1-PD-L1 immune checkpoint axis-have altered cancer treatment for many solid tumours, but few patients with gastrointestinal forms of cancer have benefited to date. There remains an urgent need to extend immunotherapy efficacy to more patients while addressing resistance to current immune checkpoint inhibitors. The aim of this study was to determine the safety and anti-tumour activity of knockout of CISH, which encodes cytokine-inducible SH2-containing protein, a novel intracellular immune checkpoint target and a founding member of the SOCS family of E3-ligases, using tumour infiltrating lymphocyte (TILs) genetically edited with CRISPR-Cas9 in patients with metastatic gastrointestinal epithelial cancers. METHODS:For this first-in-human, single-centre, phase 1 trial, patients aged 18-70 years with a diagnosis of metastatic gastrointestinal epithelial cancer with progressive disease following at least one first line standard therapy, measurable disease with at least one lesion identified as resectable for TIL generation and at least one other lesion meeting RECIST criteria as measurable to serve as an indicator of disease response, and an ECOG performance status of 0 or 1 were screened and enrolled if meeting these and all other eligibility criteria. TILs procured from tumour biopsies were expanded on the basis of neoantigen reactivity, subjected to CRISPR-Cas9-mediated CISH knockout, and infused intravenously into 12 patients after non-myeloablative lymphocyte depleting chemotherapy (cyclophosphamide 60 mg/kg per dose on study days -6 and -5, and fludarabine 25 mg/m2 per dose on days -7 to -3) followed by high-dose IL-2 (aldesleukin; 720 000 IU/kg per dose). The primary endpoint was safety of administration of neoantigen-reactive TILs with knockout of the CISH gene, and a key secondary endpoint was anti-tumour activity measured as objective radiographic response and progression-free and overall survival. This study is registered with ClinicalTrials.gov, NCT04426669, and is complete. FINDINGS:Between May 12, 2020, and Sept 16, 2022, 22 participants were enrolled in the trial (one patient was enrolled twice owing to lack of TIL outgrowth on the first attempt); ten patients were female, and 11 were male (self-defined). One patient was Asian, the remainder were White (self-defined). We successfully manufactured CISH knockout TIL products for 19 (86%) of the patients, of whom 12 (63%) received autologous CISH knockout TIL infusion. The median follow-up time for the study was 129 days (IQR 15-283). All 12 (100%) patients had treatment-related severe adverse events. The most common grade 3-4 adverse events included haematological events (12 patients [100%]) attributable to the preparative lymphodepleting chemotherapy regimen or expected effects of IL-2, fatigue (four patients [33%]), and anorexia (three patients [25%]). Deaths of any cause for patients on study were attributed to the underlying disease under study (metastatic gastrointestinal cancer) and related complications (10 patients) or infection (grade 5 septicaemia in one patient). There were no severe (≥grade 3) cytokine release or neurotoxicity events. Six (50%) of 12 patients had stable disease by day 28, and four (33%) had stable disease ongoing at 56 days. One young adult patient with microsatellite-instability-high colorectal cancer refractory to anti-PD1/CTLA-4 therapies had a complete and ongoing response (>21 months). INTERPRETATION:These results support the safety and potential antitumour activity of inhibiting the immune checkpoint CISH through the administration of neoantigen-reactive CISH-knockout TILs, with implications for patients with advanced metastatic cancers refractory to checkpoint inhibitor immunotherapies, and provide the first evidence that a novel intracellular checkpoint can be targeted with therapeutic effect. FUNDING:Intima Bioscience.

Pluripotent stem cell (PSC)-derived therapies are in clinical trials of terminally differentiated or transiently required cell types, but to date no PSC-derived trial contributing tissue-specific stem cells or any PSC-based skeletal muscle regeneration trial has been approved. We describe a process in accordance with the Current Good Manufacturing Practice (CGMP) to generate large-scale cryopreserved PAX7-induced myogenic progenitors, which reconstitute both fibers and satellite cells, from PSCs. We subjected the clinical-grade cell product MyoPAXon to biodistribution, toxicity, and tumorigenicity studies in mice under Good Laboratory Practice conditions with no adverse effects and demonstrate long-term engraftment (>1 year) and efficacy in dystrophic mice. Transplantation of 37-60 million MyoPAXon cells into immunosuppressed non-human primates showed human contribution to muscle fibers and satellite cells, with no safety concerns. The US Food and Drug Administration has recently authorized this fully characterized off-the-shelf CGMP product for a first-in-human clinical trial in Duchenne muscular dystrophy, representing the first iPSC-derived tissue-specific stem cell therapy.

INTRODUCTION:The prognosis of stage IV gastrointestinal (GI) carcinomas is poor with a 15% five-year survival rate for colorectal carcinomas. To improve efficacy of tumor infiltrating lymphocytes (TIL), we isolated mutation-reactive autologous TIL and employed CRISPR/Cas9 to knockout (KO) the intracellular checkpoint protein CISH, which has been shown to enhance T cell expansion, functional avidity, and cytokine polyfunctionality, with consequent durable regression of established tumors in an animal model. MATERIALS & METHODS:TIL cultures were initiated from resected tumor fragments and maintained for six weeks before harvest and cryopreservation. Candidate neoantigens were nominated by exome sequencing and peptides were used to identify mutation reactive (MR) TIL. Selected MR TIL were thawed and allowed to recover for 24-36 h in media with 10% AB serum, 6000 IU/mL IL-2, and 5 ng/mL IL-7 and IL-15 followed by stimulation with plate-bound anti-CD3/soluble anti-CD28 for 4 days. CISH KO was performed by electroporation of Cas9 mRNA and chemically modified single guide RNA. Between 5 -7.5 million viable cells were added to each 100 cm2 G-Rex vessel containing 600 mL expansion media (with allogeneic feeder MNC:TIL = 100:1) and incubated for 6-8 days. Cultures were evaluated and split according to cell concentration criteria (and dose cohort) and incubated for an additional 6-8 days. On day 14, all of the cells were harvested, washed with buffer and cryopreserved (5% DMSO). Lot release testing included: viability, %CD3+, cytology review, Gram stain, sterility, endotoxin, mycoplasma, and interferon gamma (IFN-γ) production. Additional testing included DNA sequencing to determine genomic CISH editing efficiency and a Western blot for determination of CISH protein loss. RESULTS:Patients with GI cancers (colon [10], rectal [8], pancreatic [1], and esophageal [1]) underwent tumor collection. Nineteen of 22 tumor biopsies sampled from 20 patients total proceeded to KO/expansion. Final TIL product results (mean [SD], median [range]) were: viable count (x 1010) -3.25 (3.67), 1.95 (0.018-12.40); viable TIL fold expansion -327.1 (364.8), 153.1 (8-1454); % viability - 76 (13), 78 (43-92); % CD3 -94.4 (5.4), 95.8 (78.6-99.4); % CISH KO efficiency - 75 (29), 87 (0-96); % editing efficiency - 59.9 (24.8), 66.9 (0.4-86). Viability fell below 70% for five TIL products. All other lot release testing has met specification. Thirteen patients have received TIL; six patients were not treated due to disease progression prior to anticipated infusion. CONCLUSION:The translation of CRISPR/Cas9-based CISH KO MR TIL from the basic research lab to current good manufacturing practices The (cGMP) facility was successful, allowing for optimized, large-scale expansion in support of a first-in-human clinical trial to treat patients with metastatic GI cancers (ClinicalTrials.gov Identifier: NCT04426669).

Given the dramatic rise in incidence of colorectal cancer in young adults, there remain limited treatment options effective in metastatic disease. Although T cell-based therapies have been successful in treating highly antigenic cancers, like melanoma and lung, they have not yet been shown to induce consistent and durable tumor regression in common epithelial malignancies, including metastatic colorectal cancer (mCRC). CISH (Cytokine inducible SH2 containing protein) is a novel intracellular checkpoint target demonstrating PD-L1 ligand independent mechanisms of enhanced anti-cancer activity. Given that CISH is not currently tractable via antibody or small molecule drug modalities, we employed CRISPR for precise inhibition of CISH in tumor infiltrating lymphocytes (TILs). Here, we provide the first clinical report of safety and anti-tumor activity of CISH edited TILs in 12 patients with metastatic gastrointestinal cancers (NCT04426669), including a clinical complete response (CR) in a young-adult patient with immunotherapy-refractory mCRC. Tumors were surgically resected for TIL harvest, followed by a rapid expansion protocol and CRISPR/Cas9 knockout (KO) CISH. CISH KO, neoantigen-reactive TILs were expanded, then infused following non-myeloablative lymphocyte depleting (LD) chemotherapy (cyclophosphamide & fludarabine) followed by high-dose IL-2. To establish mechanistic attribution of the CR, we used iR-RepSeq+ for serial analysis of the TCR immune repertoire. Our CRISPR engineering led to KO of CISH in T cells with high-efficiency (>90%) without detectable off-target editing. We safely dosed patients at all five dose levels (range: 1.91e8 to 9.93e10 cells). No dose-limiting toxicities attributable to the CISH-KO TIL product were observed. Adverse events were consistent with established risks of LD chemotherapy, IL-2, or disease progression. A durable ongoing complete response (>21 months) was achieved in a patient with microsatellite instability-high (MSI-H) mCRC refractory to anti-PD1/CTLA-4 combination therapy. We provide the first clinical report of CISH checkpoint targeting via genetically modified T cell therapy, with complete response in a patient with mCRC. Persistence and expansion of unique TCR clonotypes detected in neoantigen responsive TIL was temporally consistent with spikes in CISH edited alleles detected by NGS assay; in the patient with CR, four of the clonotypes exhibiting prolonged persistence greater than one-year post-infusion exhibited significantly reduced or undetectable expression of CISH compared to the total infused TIL population. Given these findings, further investigation of CISH checkpoint inhibition, via gene and cell therapy, and next-generation small molecule drugging modalities, is underway. Emil Lou, Modassir S. Choudhry, Timothy K. Starr, Timothy Folsom, Jason Bell, Blaine Rathmann, Anthony P. DeFeo, Ji Hyun Kim, Nicholas Slipek, Zhaohui Jin, Darin Sumstad, Christopher A. Klebanoff, Katherine Ladner, Akshat Sarkari, R Scott McIvor, Thomas A. Murray, Jeffrey Miller, Madhuri Rao, Eric Jensen, Jacob Ankeny, Mahmoud A. Khalifa, Anil Chauhan, Benjamin Spilseth, Ajay Dixit, Paolo P. Provenzano, Wenjing Pan, Daniel Weber, Miranda Byrne-Steele, Tom Henley, David H. McKenna, Matthew J. Johnson, Beau R. Webber, Branden S. Moriarity. First-in-human trial in patients with metastatic colorectal cancer using CRISPR-engineered tumor infiltrating lymphocytes in which the intracellular immune checkpoint CISH is inhibited [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr CT269.

Higher doses of infused nucleated cells (NCs) are associated with improved clinical outcomes in bone marrow transplantation (BMT) recipients. Most clinicians recommend infusing at least 2.0 × 108 NCs/kg. BMT clinicians request a target NC dose, but the harvested NC dose may be below the requested NC dose even before cell processing. We conducted this retrospective study to investigate the quality of bone marrow (BM) harvest and factors that influence infused NC doses at our institution. We also correlated infused NC doses with clinical outcomes. The study population included 347 BMT recipients (median age, 11 years; range, <1 to 75 years) at the University of Minnesota between 2009 and 2019. Underlying diagnoses mainly included 39% malignant and 61% nonmalignant diagnoses. Requested, harvested, and infused NC doses, as well as cell processing data, were obtained from the Cell Therapy Laboratory; clinical outcomes data were obtained from the University of Minnesota BMT Database. BM harvests were facilitated either by our institution (61%) or by the National Marrow Donor Program (39%). Associations of infused doses with baseline characteristics were assessed using the general Wilcoxon test/Pearson's correlation coefficient. The association of infused dose with neutrophil engraftment (absolute neutrophil count >500) by day 42, platelet engraftment (>20,000) by 6 months, acute graft-versus-host disease grade II-IV, and overall survival (OS) at 5 years were evaluated using regression and Kaplan-Meier curves. The median requested NC dose was 3.0 × 108/kg (range, 2 to 8 × 108/kg), and the median harvested and infused NC doses were 4.0 × 108/kg and 3.6 × 108/kg, respectively. Only 7% of donors had a harvested dose below the minimum requested dose. Moreover, the correlation between requested doses and harvested doses was adequate, with a harvested/requested dose ratio <.5 observed in only 5% of harvests. Additionally, the harvest volume and cell processing method were significantly correlated with the infused dose. Harvest volume exceeding the median of 948 mL was related to a significantly lower infused dose (P < .01). Moreover, hydroxyethyl starch (HES)/buffy coat processing (used to reduce RBCs with major ABO incompatibility) led to a significantly lower infused dose (P < .01). Donor age (median, 19 years; range, <1 to-70 years) and sex did not significantly influence the infused dose. Finally, the infused dose was significantly correlated with neutrophil and platelet engraftment (P < .05) but not with 5-year OS (P = .87) or aGVHD (P = .33). In our program's experience, BM harvesting is efficient and meets the requested minimum dose for 93% of recipients. Harvest volume and cell process play significant roles in determining the final infused dose. Minimizing harvest volume and cell processing could lead to increased infused dose and thus improved outcomes. Moreover, a higher infused dose leads to a better rate of neutrophil and platelet engraftment but not to improved OS, which may be linked to the sample size of our study.

While neoantigen-specific tumor infiltrating lymphocytes (TIL) can be derived from in antigen-expressing tumors, their adoptive transfer fails to consistently elicit durable tumor regression. There has been much focus on the role of activation/exhaustion markers such as PD1, CD39 and TOX in TIL senescence. We found these markers were inversely expressed to Cytokine-Induced SH2 protein (CISH), a negative regulator of TCR signaling and tumor immunity in mice. To evaluate the physiological role of CISH in human TIL we developed a high-efficiency CRIPSR-based method to knock out CISH in fully mature TIL. CISH KO resulted in increased T cell receptor (TCR) avidity, tumor cytolysis and neoantigen recognition. CISH expression in the tumor resections correlated with TIL inactivity against p53 hotspot mutations and CISH KO in TIL unmasked reactivity against these universal neoantigens. While CISH KO resulted in T cell hyperactivation and expansion it did not alter maturation, perhaps by preferential PLCγ-1 and not AKT inhibition. Lastly, CISH KO in T cells increased PD1 expression and the adoptive transfer of Cish KO T cells synergistically combines with PD1 antibody blockade resulting in durable tumor regression and survival in a preclinical animal model. These data offer new insights into the regulation of neoantigen recognition, expression of activation/exhaustion markers, and functional/maturation signals in tumor-specific T cells.

Background aims: The final harvest or wash of a cell therapy product is an important step in manufacturing, as viable cell recovery is critical to the overall success of a cell therapy. Most harvest/wash approaches in the clinical lab involve centrifugation, which can lead to loss of cells and decreased viability of the final product. Here the authors report on a multi-center assessment of the LOVO Cell Processing System (Fresenius Kabi, Bad Homburg, Germany), a cell processing device that uses a spinning filtration membrane instead of centrifugation.Methods: Four National Institutes of Health Production Assistance for Cellular Therapies cell processing facilities (CPFs) assessed the LOVO Cell Processing System for final harvest and/or wash of the following three different cell products: activated T cells (ATCs), tumor-infiltrating lymphocytes (TILs) and bone marrow derived mesenchymal stromal cells (MSCs). Each site compared their current in-house, routinely used method of final cell harvest and/or wash with that of the LOVO device. Results: Final harvest and/or wash of ATCs, TILs and MSCs using the LOVO system resulted in satisfactory cell viability and recovery with some substantial improvement over the in-house methods of CPFs. Processing time was variable among cell types/facilities.Conclusions: The LOVO Cell Processing System provides an alternative to centrifuge-based technologies. The system employs a spinning membrane filter, exposing cells to minimal g-forces compared with centrifugation, and is automated and closed. This small multi-center study demonstrated the ability of the LOVO device to yield satisfactory cell viability and recovery of T cells and MSCs.(c) 2022 International Society for Cell & Gene Therapy. Published by Elsevier Inc. All rights reserved.

Background: Adoptive transfer of tumor-infiltrating lymphocytes (TIL) fails to consistently elicit tumor rejection. Manipulation of intrinsic fac-tors that inhibit T cell effector function and neoantigen recognition may therefore improve TIL therapy outcomes. We previously identified the cytokine-induced SH2 protein (CISH) as a key regulator of T cell functional avidity in mice. Here, we investigate the mechanistic role of CISH in regulating human T cell effector function in solid tumors and demonstrate that CRISPR/Cas9 disruption of CISH enhances TIL neoan-tigen recognition and response to checkpoint blockade.Methods: Single-cell gene expression profiling was used to identify a negative correlation between high CISH expression and TIL activation in patient-derived TIL. A GMP-compliant CRISPR/Cas9 gene editing process was developed to assess the impact of CISH disruption on the molecular and functional phenotype of human peripheral blood T cells and TIL. Tumor-specific T cells with disrupted Cish function were adoptively transferred into tumor-bearing mice and evaluated for efficacy with or without checkpoint blockade.Findings: CISH expression was associated with T cell dysfunction. CISH deletion using CRISPR/Cas9 resulted in hyper-activation and improved functional avidity against tumor-derived neoantigens without perturb-ing T cell maturation. Cish knockout resulted in increased susceptibility to checkpoint blockade in vivo.Conclusions: CISH negatively regulates human T cell effector function, and its genetic disruption offers a novel avenue to improve the thera-peutic efficacy of adoptive TIL therapy.Funding: This study was funded by Intima Bioscience, U.S. and in part through the Intramural program CCR at the National Cancer Institute.

Human CD4+25- T cells cultured in interleukin 2 (IL-2), rapamycin, and transforming growth factor β (TGFβ) along with anti-CD3 monoclonal antibody-loaded artificial antigen-presenting cells generate FoxP3+ induced regulatory T cells (iTregs) with potent suppressive function. We performed a phase 1, single-center, dose-escalation study to determine the safety profile of iTregs in adults with high-risk malignancy treated with reduced-intensity conditioning and mobilized peripheral blood stem cells (PBSCs) from HLA-identical sibling donors. Sixteen patients were enrolled and 14 were treated (2 productions failed to meet desired doses). One patient each received 3.0 × 106/kg, 3.0 × 107/kg, and 3.0 × 108/kg iTregs with corresponding T-conventional-to-iTreg ratios of 86:1, 8:1, and 1:2. After 3 patients received 3.0 × 108/kg in the presence of cyclosporine (CSA) and mycophenolate mofetil (MMF) with no dose-limiting toxicities, subsequent patients were to receive iTregs in the presence of sirolimus/MMF that favors Foxp3 stability based on preclinical modeling. However, 2 of 2 developed grade 3 acute graft-versus-host disease (GVHD), resulting in suspension of the sirolimus/MMF. An additional 7 patients received 3.0 × 108/kg iTregs with CSA/MMF. In the 14 patients treated with iTregs and CSA/MMF, there were no severe infusional toxicities with all achieving neutrophil recovery (median, day 13). Of 10 patients who received 3.0 × 108/kg iTregs and CSA/MMF, 7 had no aGVHD, 2 had grade 2, and 1 had grade 3. Circulating Foxp3+ iTregs were detectable through day 14. In summary, iTregs in the context of CSA/MMF can be delivered safely at doses as high as 3 × 108/kg. This trial was registered at www.clinicaltrials.gov as #NCT01634217.

Background Neoantigen-specific T cells isolated from tumors have shown promise clinically but fail to consistently elicit durable tumor regression. Expression of the intracellular checkpoint CISH is elevated in human tumor infiltrating lymphocytes (TIL) and has been shown to inhibit neoantigen reactivity in murine TIL. Methods To explore CISH function in human T cells we developed a CRISPR/Cas9-based strategy to knockout (KO) CISH in human T cells with high-efficiency (>90%) and without detectable off-target editing. Results CISH KO in peripheral blood T cells enhanced proliferation, cytokine polyfunctionality, and cytotoxicity in vitro. To determine if CISH KO similarly enhances TIL function, we developed a clinical-scale, GMP-compliant manufacturing process for CISH disruption in primary human TIL. In process validation runs we achieved CISH KO efficiencies >90% without detectable off-target editing while maintaining high viability and expansion. Compared to WT controls, CISH KO in patient-derived TIL demonstrated increased proliferation, T cell receptor (TCR) avidity, neoantigen recognition, and unmasked reactivity to common p53 mutations. Hyperactivation in CISH KO TIL did not increase differentiation, suggesting that CISH KO may uncouple activation and differentiation pathways. Single cell profiling identifies a pattern of CISH expression inverse to key regulators of activation, and CISH KO in human TIL increases PD1 expression. Adoptive transfer of Cish KO T cells synergistically combines with PD1 inhibition resulting in durable tumor regression in mice, highlighting orthogonal dual cell surface and intracellular checkpoint inhibition as a novel combinatorial approach for T cell immunotherapy. Conclusions These pre-clinical data offer new insight into neoantigen recognition and serve as the basis for a recently initiated human clinical trial at the University of Minnesota (NCT04426669) evaluating inhibition of the novel intracellular immune checkpoint CISH in a CRISPR-engineered, neoantigen-specific T cell therapy for solid tumors. Updates from the clinical trial will be highlighted. Trial Registration NCT04426669

Background HSC dose and HLA match are risk factors that impact mortality using cord blood units (CBU) in transplant. Low CD34+ doses result in prolonged cytopenia and higher graft failure risk. A minimum cell dose of 3.0 × 107 total nucleated cells (TNC)/kg has generally been required in CBU selection; however, cell dose limits often require the use of a 2nd unit and markedly limits the availability of 7-8/8 HLA-matched units in larger patients. MGTA-456 is a cell therapy product utilizing an aryl hydrocarbon receptor antagonist for expansion of CD34+ HSCs in vitro. In prior studies with fresh MGTA-456, 36 patients with hematologic malignancies demonstrated rapid neutrophil recovery and 100% engraftment. This study (NCT03674411) will evaluate the safety and efficacy of cryopreserved MGTA-456 and the effectiveness of lowering the TNC threshold of the selected CBU to 1.0 × 107 TNC/kg before expansion to improve HLA match. Methods 13 patients aged 2-47 years (12-159 kg) with high-risk hematologic malignancy were enrolled with 11 transplanted to date. Patients received cyclophosphamide 120 mg/kg, fludarabine 75 mg/m2 and total body irradiation 1320 cGy or a busulfan-based regimen for children ≤3 years of age prior to MGTA-456 with cyclosporine/mycophenolate mofetil prophylaxis. G-CSF began the day after infusion until the neutrophil count exceeded 2500/uL for 3 days. Results MGTA-456 contained a median 2.3 × 109 CD34+ cells (range, 0.65-8.0) after expansion (422-fold expansion of CD34+ cells [range, 219-1313]). Neutrophil recovery occurred in all patients with a median of 15 days (range, 0-31), similar to recipients of fresh MGTA-456 in a prior study (median 14 days) and significantly faster than in recipients of unmodified CBUs (median 25 days). Median platelet recovery was 41 days (range 24-49) vs 64 days with unmodified CBUs. MGTA-456 CD34+CD90+ content strongly correlated with speed of neutrophil recovery (Fig. 1), consistent with preclinical murine data showing CD34+CD90+ cells represent the true engraftable HSC population. Lowering the TNC requirement to 1.0 × 107 TNC/kg for CBU selection pre-expansion improved HLA match and/or eliminated the need for double CBU transplant in all 5 patients weighing >80 kg. Three patients received 8/8 grafts who would have otherwise received 1 or 2 6/8 units (n=2) or two 7/8 units (n=1) which may account for the low incidence of aGVHD overall (3 cases of Grade 1-2 and no Grade 3-4). With a follow-up of 5.2 months (0.4-8.5 months), all patients are alive. Conclusion Cryopreserved MGTA-456 cell therapy resulted in rapid and 100% engraftment with speed of neutrophil recovery correlating with CD34+CD90+ cell dose in patients with high risk hematologic malignancy. Expansion of smaller CBUs increases the chance of finding a better HLA match, particularly for adults, thus reducing the barriers associated with low cell dose and poor HLA match in CBU transplantation.

BackgroundPatient access to well-matched cord blood (CB) containing high doses of stem cells remains a challenge for successful transplants. Low numbers of CD34+ cells in CB has resulted in delayed neutrophil recovery and increased risk of graft failure. MGTA-456 is a cell therapy that consists of CD34+ cells expanded in a 15-day culture in the presence of an aryl hydrocarbon receptor antagonist (AHRa) and the CD34 depleted fraction obtained from the same CB unit. To date, 41 patients with hematological malignancies (n=36) and non-malignant diseases (n=5) have received MGTA-456 with a median follow-up of 2.5 years (range 0.1 to 5 years) and 75 days (80 to 203 days), respectively. All patients engrafted at a significantly faster rate as compared to similarly treated historical controls (p<0.01). The aim of the current study was to fully characterize the expanded CD34+ cell product of MGTA-456 phenotypically and functionally to identify the cell population that correlates with time to neutrophil recovery. We found that the CD34+CD90+ population of MGTA-456 were the cells responsible for engraftment in NOD-scid IL2Rgammanull (NSG) mice and have the strongest correlation with time to neutrophil recovery in patients.ResultsAfter the selected CD34+ cells are cultured, the expanded product is ∼35% CD34+ and 65% CD34- (Figure 1). The CD34+ cells can be further fractionated into CD34+CD133-CD90- cells (late progenitors), CD34+CD133+CD90- cells (early progenitors) and CD34+CD133+CD90+ (progenitors and stem cells) as shown in Figure 1. The CD34- cells within the expanded product contained erythroid (CD71+) and megakaryocyte progenitors (CD41+), CD33+, CD14+, CD15+, and CD11b+ myeloid cells and CD56+ cells. CD3+, CD8+, CD4+, CD16+, CD19+ as well as CD10+ cells were not present (<1%) in MGTA-456. To identify which of these cell populations within MGTA-456 drug product contain the NSG engraftment activity, we sorted CD34-, CD34+CD90- and CD34+CD90+ cells from the MGTA-456 drug product and transplanted the cell fractions into NSG mice. These studies clearly demonstrated that all NSG engraftment activity resided in the CD34+CD90+ cell subpopulation (Figure 2). Based on this result, we correlated the dose of CD34-, CD34+CD90-, CD34+CD90+, and CFU cells/kg infused with time to neutrophil recovery of patients treated with MGTA-456. The dose of TNC (r2=0.49, P<0.05), CD34+CD90- (r2=0.45, p<0.05) and CD34+CD90+ (r2=0.52, p<0.05) cells/kg all significantly correlated with time to neutrophil recovery. The dose of CD34+CD90+ cells/kg had the strongest correlation with time to neutrophil recovery consistent with the NSG engraftment result.ConclusionIn these studies, we demonstrate that the expanded CD34+ cell fraction of MGTA-456 contains large numbers of CD34+CD90+ HSC, which are critical for long term engraftment in NSG mice and correlated with rapid neutrophil recovery clinically. Patient access to well-matched cord blood (CB) containing high doses of stem cells remains a challenge for successful transplants. Low numbers of CD34+ cells in CB has resulted in delayed neutrophil recovery and increased risk of graft failure. MGTA-456 is a cell therapy that consists of CD34+ cells expanded in a 15-day culture in the presence of an aryl hydrocarbon receptor antagonist (AHRa) and the CD34 depleted fraction obtained from the same CB unit. To date, 41 patients with hematological malignancies (n=36) and non-malignant diseases (n=5) have received MGTA-456 with a median follow-up of 2.5 years (range 0.1 to 5 years) and 75 days (80 to 203 days), respectively. All patients engrafted at a significantly faster rate as compared to similarly treated historical controls (p<0.01). The aim of the current study was to fully characterize the expanded CD34+ cell product of MGTA-456 phenotypically and functionally to identify the cell population that correlates with time to neutrophil recovery. We found that the CD34+CD90+ population of MGTA-456 were the cells responsible for engraftment in NOD-scid IL2Rgammanull (NSG) mice and have the strongest correlation with time to neutrophil recovery in patients. After the selected CD34+ cells are cultured, the expanded product is ∼35% CD34+ and 65% CD34- (Figure 1). The CD34+ cells can be further fractionated into CD34+CD133-CD90- cells (late progenitors), CD34+CD133+CD90- cells (early progenitors) and CD34+CD133+CD90+ (progenitors and stem cells) as shown in Figure 1. The CD34- cells within the expanded product contained erythroid (CD71+) and megakaryocyte progenitors (CD41+), CD33+, CD14+, CD15+, and CD11b+ myeloid cells and CD56+ cells. CD3+, CD8+, CD4+, CD16+, CD19+ as well as CD10+ cells were not present (<1%) in MGTA-456. To identify which of these cell populations within MGTA-456 drug product contain the NSG engraftment activity, we sorted CD34-, CD34+CD90- and CD34+CD90+ cells from the MGTA-456 drug product and transplanted the cell fractions into NSG mice. These studies clearly demonstrated that all NSG engraftment activity resided in the CD34+CD90+ cell subpopulation (Figure 2). Based on this result, we correlated the dose of CD34-, CD34+CD90-, CD34+CD90+, and CFU cells/kg infused with time to neutrophil recovery of patients treated with MGTA-456. The dose of TNC (r2=0.49, P<0.05), CD34+CD90- (r2=0.45, p<0.05) and CD34+CD90+ (r2=0.52, p<0.05) cells/kg all significantly correlated with time to neutrophil recovery. The dose of CD34+CD90+ cells/kg had the strongest correlation with time to neutrophil recovery consistent with the NSG engraftment result. In these studies, we demonstrate that the expanded CD34+ cell fraction of MGTA-456 contains large numbers of CD34+CD90+ HSC, which are critical for long term engraftment in NSG mice and correlated with rapid neutrophil recovery clinically.

Background. HSC dose and HLA match are independent risk factors that impact non-relapse mortality in children and adults undergoing umbilical cord blood (UCB) transplant for acute leukemia (Eapen et al. Blood 2014 123:133-140). Low number of CD34+ HSCs results in prolonged periods of cytopenia and higher risk of graft failure. To reduce these risks, a minimum cell dose threshold, e.g. 3.0 x 107 total nucleated cells (TNC)/kilogram (kg), has generally been required in CBU selection. While beneficial in terms of hematopoietic recovery, this cell dose threshold markedly limits the number of available cord blood units (CBUs) particularly for larger adolescent and adult recipients, thus reducing the probability of identifying a 7-8/8 HLA-matched graft. In addition, a second UCB unit is often required for adults as a single unit may not meet the cell dose threshold. MGTA-456 is an expanded CD34+ HSC product utilizing an AHR antagonist in the presence of SCF, Flt-3L, IL-6 and TPO. In previous studies with fresh MGTA-456, 36 patients with hematologic malignancies demonstrated rapid neutrophil recovery and sustained engraftment in all patients. The aims of this study (NCT03674411) were to evaluate the safety and efficacy of cryopreserved MGTA-456 as well as the effectiveness of lowering the minimum cell dose threshold of the selected CBU from 3.0 x 107 to 1.0 x 107 TNC/kg to improve donor-recipient HLA match. Patients and Methods: Ten patients with high-risk hematologic malignancy were enrolled with 9 transplanted to date. Conditioning consisted of cyclophosphamide 120 mg/kg, fludarabine 75 mg/m2 and total body irradiation 1320 cGy (total doses) with cyclosporine and mycophenolate mofetil as immunoprophylaxis. G-CSF was initiated on the day after infusion and continued until the neutrophil count exceeded 2500/uL for 3 consecutive days. Results: Cryopreserved MGTA-456 contained a median of 1.9 x 109 CD34+ cells (range, 1.1-6.2) after expansion culture (a 491-fold expansion of CD34+ cells [range, 219-672]). As shown in Table 1, neutrophil recovery occurred in 100% of patients (with one pending after recent transplant) at a median of 15 days (range, 0-31), similar to recipients of fresh MGTA-456 in a prior study (median 14 days, range 7-32) and significantly faster than in recipients of unmodified UCB (median 25 days). Platelet recovery (>20,000/uL for 7 days without transfusion) was also comparable in recipients of cryopreserved and fresh MGTA-456 (median 42 [range 27-53] vs 45 days [range 28-54], respectively), and again faster relative to recipients of unmodified CBUs (median 64 days). In line with preclinical experiments in NSG murine recipients that demonstrates all engrafting cells are retained in the CD34+CD90+ subpopulation, CD34+CD90+ content strongly correlated with speed of neutrophil recovery in recipients of MGTA-456 (cryopreserved and fresh) as shown in Figure 1. As expected, lowering the cell dose requirement from 3.0 x 107 to 1.0 x 107 TNC/kg for UCB unit selection prior to expansion culture improved HLA match and/or eliminated the need for double UCB transplant in 5 of 6 adults (Table 1). As a result, all but one patient received an 8/8 (n=5) and 7/8 (n=4) HLA matched UCB graft, potentially contributing to the low incidence of acute GVHD with only one patient of the 7 out >42 days having grade 2 acute GVHD. This low rate of GVHD compares favorably to that observed in the prior study of fresh MGTA-456. With a follow-up of 19-187 days (median 89), all patients are alive. Conclusion: Transplantation of cryopreserved MGTA-456 resulted in complete engraftment and rapid recovery with speed of neutrophil recovery correlating with the CD34+CD90+ cell dose. Based on the marked expansion that is now possible, units with fewer cells can now be considered, increasing the probability of finding a better HLA matched unit, particularly for adults. Availability of MGTA-456 could reduce the barriers associated with cell dose and poor HLA match previously limiting the successful use of UCB in transplantation. Disclosures Stefanski: Novartis: Consultancy, Speakers Bureau. Brunstein:Magenta: Research Funding; Gamida: Research Funding; Astex: Research Funding. McKenna:Icahn School of Medicine, New York, New York: Consultancy; CIBMTR BMT CTN (NIH): Other: Medical Monitor; National Eye Institute (NIH): Other: DSMB (2); Magenta Therapeutics: Research Funding; Gamida: Research Funding; NMDP: Other: Donor and Patient Safety Monitoring Advisory Group; Fate Therapeutics: Research Funding; Intima: Patents & Royalties: Royalities, Research Funding. Miller:Dr. Reddys Laboratory: Membership on an entity's Board of Directors or advisory committees; Moderna: Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics, Inc: Consultancy, Research Funding; GT BioPharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; CytoSen: Membership on an entity's Board of Directors or advisory committees; OnKImmune: Membership on an entity's Board of Directors or advisory committees. Blazar:KidsFirst Fund: Research Funding; Childrens' Cancer Research Fund: Research Funding; Abbvie Inc: Research Funding; Leukemia and Lymphoma Society: Research Funding; Kamon Pharmaceuticals, Inc: Membership on an entity's Board of Directors or advisory committees; Magenta Therapeutics and BlueRock Therapeuetics: Membership on an entity's Board of Directors or advisory committees; Five Prime Therapeutics Inc: Co-Founder, Membership on an entity's Board of Directors or advisory committees; Regeneron Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Alpine Immune Sciences, Inc.: Research Funding; RXi Pharmaceuticals: Research Funding; Fate Therapeutics, Inc.: Research Funding; Tmunity: Other: Co-Founder; BlueRock Therapeutics: Membership on an entity's Board of Directors or advisory committees. Boitano:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Cooke:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Raffel:Magenta Therapeutics: Employment, Equity Ownership. Davis:Magenta Therapeutics: Employment, Equity Ownership. Wagner:Rocket Pharmaceuticals: Consultancy; Magenta: Consultancy, Research Funding; BlueRock: Research Funding; Gadeta: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding.

BACKGROUNDAllogeneic natural killer (NK) cell adoptive immunotherapy is a growing therapeutic option for patients. Clinical-scale production of NK cells using immunomagnetic selection complies with current good manufacturing practices (cGMPs) and allows for closed-system, automated purification. We report our experience with CD3/CD19 cell-depleted (CD3/CD19(dep)) NK cell production and compare to previous methods of CD3 cell depletion and CD3 cell depletion/CD56 cell enrichment. STUDY DESIGN AND METHODSNonmobilized mononuclear cells collected by apheresis were incubated with anti-CD3/anti-CD19 microbeads and depleted in an automated cell selection system (CliniMACS, Miltenyi). The NK cell-enriched products were incubated overnight in interleukin (IL)-2 or IL-15, washed, and resuspended prior to lot release testing and infusion. RESULTSSince 2010, 94 freshly infusible CD3/CD19(dep) NK cell products were manufactured in support of eight clinical trials. Sixty-six products were incubated in IL-2 and 28 products in IL-15. Processing resulted in a mean NK cell recovery of 74% and viability of 95.8%; NK cells, T cells, B cells, and monocytes accounted for 47%, 0.2%, 0.08%, and 49% of the final products, respectively. Seven products required dose adjustments to meet lot release. The specification for purity changed throughout the evolution of manufacturing. IL-2 or IL-15 activation enhanced in vitro cytotoxicity compared to preactivated cells. There was no difference in final product composition or cytotoxicity between cytokine cohorts. CONCLUSIONClinical-scale/cGMP production of NK cells using CD3/CD19 cell-depletion effectively minimized T-cell and B-cell contamination in a single manipulation without compromise to NK-cell recovery. Cytokine activation increased in vitro cytotoxicity compared to column-depleted, preactivated NK cells.

Background: Patient access to well-matched CB containing high doses of stem cells remains a challenge for successful transplants. Low numbers of CD34+ cells in CB has resulted in delayed neutrophil recovery and a risk of graft failure relative to other hematopoietic stem cell (HSC) sources. MGTA-456 is a cell therapy that consists of CD34+ cells expanded in a 15-day culture in the presence of an aryl hydrocarbon receptor antagonist (AHRa) and the CD34 depleted fraction obtained from the same CB unit. Thus far, 40 patients with hematological malignancy (n=36) and non-malignant diseases (n=4) have received MGTA-456 with a median follow-up of 2.5 years (range 0.1 to 5 years) and 75 days (20 to 143 days) respectively. All patients engrafted at a significantly faster rate as compared to similarly treated historical controls (p<0.01). The aim of the current study was to fully characterize the expanded CD34+ cell fraction of MGTA-456 phenotypically and functionally and identify the cell population that correlates with time to neutrophil recovery. We found that the expanded CD34+CD90+ population of MGTA-456 were the cells responsible for engraftment in NOD-scid IL2Rgammanull (NSG) mice. We hypothesized that the dose of CD34+CD90+ cells/kg would have the strongest correlation with time to neutrophil recovery.