Cell Dose Research Articles

Phase I trial and preclinical data of ACT using neoantigen-reactive TIL for patients with advanced epithelial and ICB-resistant solid cancers

Background and PurposeACT of ex vivo expanded TIL can mediate objective tumor regression in 28-49% of metastatic melanoma patients. However, the efficacy of TIL therapy in most epithelial cancers remains limited. We present the design of a phase I clinical study that aims to assess the safety and efficacy of NEXTGEN-TIL, a TIL product selected based on ex vivo neoantigen recognition, in patients with advanced epithelial tumors and ICB-resistant solid tumors. MethodsPreREP TIL cultures expanded in high dose IL-2 (HD-IL-2) from patients with metastatic solid tumors were screened for recognition of autologous TCL and/or neoantigens. 6 GMP validations of preREP TIL expansion were performed and TIL cultures from these 6 intermediate products were selected to perform the clinical scale GMP validation of the REP. ResultsTIL expanded in 82% of patient-derived tumor biopsies across different cancer types and these contained tumor- and neoantigen-reactive T cells. During GMP-validations, a variable number of TILs expanded, constituting the intermediate products (preREP). Three finished products (REP) were manufactured which reached cell doses ranging from 4.3e9 to 1.1e11 and met the established specifications. The NEXTGEN-TIL clinical trial entails a first expansion of TIL from tumor fragments in HD-IL-2 followed by TIL screening for neoantigen-recognition and REP of selected neoantigen-reactive TIL cultures. Treatment involves a classical non-myeloablative lymphodepleting chemotherapy followed by NEXTGEN-TIL product administration together with HD-IL-2. ConclusionsNEXTGEN-TIL consists of selected neoantigen-reactive TIL and aims to potentially improve efficacy in patients with epithelial and ICB-resistant tumors, with a safety profile like traditional TIL.

Safety and activity of CTX130, a CD70-targeted allogeneic CRISPR-Cas9-engineered CAR T-cell therapy, in patients with relapsed or refractory T-cell malignancies (COBALT-LYM): a single-arm, open-label, phase 1, dose-escalation study

Effective treatment options are scarce for relapsed or refractory T-cell lymphoma. This study assesses the safety and activity of CTX130 (volamcabtagene durzigedleucel), a CD70-directed, allogeneic chimeric antigen receptor (CAR) immunotherapy manufactured from healthy donor T cells, in patients with relapsed or refractory T-cell lymphoma. This single-arm, open-label, phase 1 study was done at ten medical centres across the USA, Australia, and Canada in patients (aged ≥18 years) with relapsed or refractory peripheral T-cell lymphoma or cutaneous T-cell lymphoma, who had received at least one or at least two previous systemic therapy lines, respectively, and had an Eastern Cooperative Oncology Group (ECOG) performance status of 0-1. Patients underwent lymphodepletion with fludarabine 30 mg/m2 and cyclophosphamide 500 mg/m2 (intravenously daily for 3 days), followed by intravenous CTX130 infusion at dose levels ranging from 3 × 107 CAR+ T cells (dose level 1) to 9 × 108 CAR+ T cells (dose level 4). The primary endpoint was the incidence of adverse events, defined as dose-limiting toxicities occurring within 28 days post-infusion. Secondary endpoints included objective response rate. Safety and activity analyses were performed on data from all patients who received CTX130. The trial is registered with ClinicalTrials.gov (NCT04502446) and EudraCT (2019-004526-25) and is closed to enrolment. Between Aug 28, 2020, and May 30, 2023, 41 patients were enrolled and 39 (95%) received CTX130. The median patient follow-up was 7·4 months (IQR 3·1-12·2). 21 (54%) of 39 patients were female and 18 (46%) were male. 24 (62%) patients were White, eight (21%) were Black, three (8%) were Asian, three (8%) were from other racial or ethnic groups, and one (3%) was not reported. The median number of previous lines of anticancer therapy was 2·5 (IQR 1·3-4·0) for patients with peripheral T-cell lymphoma and 5·0 (IQR 5·0-7·0) for patients with cutaneous T-cell lymphoma. Cytokine release syndrome was the most common adverse event, occurring in 26 (67%) of 39 patients (23 were grade 1-2, two were grade 3, and one was a grade 4 dose-limiting toxicity at dose level 4). Grade 1-2 neurotoxic events were observed in four (10%) of 39 patients. The most common grade 3-4 adverse events were neutropenia (14 [36%]), anaemia (11 [28%]), and thrombocytopenia (six [15%]). Serious adverse events occurred in 25 (64%) patients, with CTX130-related serious adverse events in 14 (36%) patients, the most common related serious adverse event being cytokine release syndrome in 11 (28%) patients. 21 patients died, 16 from progressive disease and five from adverse events considered unrelated to CTX130 treatment. 18 of 39 patients (46·2% [95% CI 30·1-62·8) had an objective response. Of those treated at dose level 3 and higher, 16 of 31 patients (51·6% [33·1-69·8]) had objective responses, including six (19·4% [7·5-37·5]) with complete response and ten (32·3% [16·7-51·4]) with a partial response. In patients with heavily pretreated T-cell lymphoma, CTX130 showed manageable safety and a promising objective response rate. This study shows that allogeneic, readily available CAR T cells can be safely given to patients with relapsed or refractory T-cell lymphoma. A next-generation CAR T-cell therapy containing additional potency gene edits (CTX131) is in clinical development. CRISPR Therapeutics.

Preclinical safety and efficacy evaluation of the intrathecal transplantation of GMP-grade human umbilical cord mesenchymal stem cells for ischemic stroke.

Intrathecal administration of human umbilical cord mesenchymal stem cells may be a promising approach for the treatment of stroke, but its safety, effectiveness, and mechanism remain to be elucidated. In this study, good manufacturing practice-grade human umbilical cord mesenchymal stem cells (5 × 105 and 1 × 106 cells) and saline were administered by cerebellomedullary cistern injection 72 hours after stroke induced by middle cerebral artery occlusion in rats. The results showed (1) no significant difference in mortality or general conditions among the three groups. There was no abnormal differentiation or tumor formation in various organs of rats in any group. (2) Compared with saline-treated animals, those treated with human umbilical cord mesenchymal stem cells showed significant functional recovery and reduced infarct volume, with no significant differences between different human umbilical cord mesenchymal stem cell doses. (3) Human umbilical cord mesenchymal stem cells were found in the ischemic brain after 14 and 28 days of follow-up, and the number of positive cells significantly decreased over time. (4) Neuronal nuclei expression in the human umbilical cord mesenchymal stem cell group was greater than that in the saline group, while glial fibrillary acidic protein and ionized calcium binding adaptor molecule 1 expression levels decreased. (5) Human umbilical cord mesenchymal stem cell treatment increased the number of CD31+ microvessels and doublecortin-positive cells after ischemic stroke. Human umbilical cord mesenchymal stem cells also upregulated the expression of CD31+/Ki67+. (6) At 14 days after intrathecal administration, brain-derived neurotrophic factor expression in the peri-infarct area and the concentrations of brain-derived neurotrophic factor in the cerebrospinal fluid in both human umbilical cord mesenchymal stem cell groups were significantly greater than those in the saline group and persisted until the 28th day. Taken together, these results indicate that the intrathecal administration of human umbilical cord mesenchymal stem cells via cerebellomedullary cistern injection is safe and effective for the treatment of ischemic stroke in rats. The mechanisms may include alleviating the local inflammatory response in the peri-infarct region, promoting neurogenesis and angiogenesis, and enhancing the production of neurotrophic factors.

An empirical model of carbon-ion relative biological effectiveness based on the linear correlation between radiosensitivity to photons and carbon ions.

To develop an empirical model to predict carbon ion (C-ion) relative biological effectiveness (RBE). 

Approach. We used published cell survival data comprising 360 cell line/energy combinations to characterize the linear energy transfer (LET) dependence of cell radiosensitivity parameters describing the dose required to achieve a given survival level, e.g. 5% (D5%), which are linearly correlated between photon and C-ion radiations. Based on the LET response of the metrics D5% and D37%, we constructed a model containing four free parameters that predicts cells' linear quadratic model (LQM) survival curve parameters for C-ions, αCand βC, from the reference LQM parameters for photons, αXand βX, for a given C-ion LET value. We fit our model's free parameters to the training dataset and assessed its accuracy via leave-one out cross-validation. We further compared our model to the local effect model (LEM) and the microdosimetric kinetic model (MKM) by comparing its predictions against published predictions made with those models for clinically relevant LET values in the range of 23-107 keV/μm. 

Main Results. Our model predicted C-ion RBE within ±7%-15% depending on cell line and dose which was comparable to LEM and MKM for the same conditions. 

Significance. Our model offers comparable accuracy to the LEM or MKM but requires fewer input parameters and is less computationally expensive and whose implementation is so simple we provide it coded into a spreadsheet. Thus, our model can serve as a pragmatic alternative to these mechanistic models in cases where cell-specific input parameters cannot be obtained, the models cannot be implemented, or for which their computational efficiency is paramount.

CTIM-04. MODULATION OF THE INTRATUMORAL IMMUNE MICROENVIRONMENT BY LOCAL THERAPY WITH NATURAL KILLER CELLS ENGINEERED WITH A HER2-TARGETED CHIMERIC ANTIGEN RECEPTOR IN COMBINATION WITH SYSTEMIC ANTI-PD-1 CHECKPOINT INHIBITION IN PATIENTS WITH RECURRENT GLIOBLASTOMA

Abstract Glioblastoma (GB) is characterized by a marked immunosuppressive tumor microenvironment. In the multicenter CAR2BRAIN phase I first-in-human clinical trial, we investigated the modulation of the tumor microenvironment by repetitive local injection of clonal chimeric antigen receptor (CAR)-NK cells (NK-92/5.28.z) targeting HER2 alone and in combination with systemic anti-PD-1 checkpoint inhibitor therapy in patients with recurrent HER2-positive GB. 6 patients were treated with repetitive doses of CAR-NK cells as monotherapy and 12 patients received a combination therapy with the anti-PD-1 checkpoint inhibitor ezabenlimab. In three of those, we were able to implement a biopsy-treat-resect-treat strategy. After initial biopsy, combination treatment was initiated before planned tumor resection, enabling analysis of the transformation of the tumor immune microenvironment by highplex multispectral fluorescent analyses and cytokine quantification. None of the patients developed a cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome. Profound alterations of the immune cell distribution in the cerebrospinal fluid (CSF) and in the tumor were observed. In CSF sampled from the resection cavity, combination immunotherapy induced a local immune response with elevated pro-inflammatory cytokines and cell counts. In post-treatment tissue samples, we observed an increase of CD4+ and CD8+ T cells, and a decrease of regulatory CD4+FoxP3+ T cells. The three patients treated following the biopsy-treat-resect-treat strategy achieved a median progression-free survival (PFS) of 24 weeks, compared to 10 weeks for patients with upfront resection. Local immunotherapy with HER2-targeted CAR-NK cells is feasible and safe both as monotherapy and in combination with the systemic checkpoint inhibitor ezabenlimab and induces local immune reactions in CSF and tumor tissue. Given the signal for possible clinical benefit provided by the increase in PFS in the patients of the biopsy-treat-resect-treat cohort, further trials are warranted.

Application of CAR-T cell therapy in B-cell lymphoma: a meta-analysis of randomized controlled trials.

This study aims to compare the efficacy and safety of chimeric antigen receptor T-cell (CAR-T) immunotherapy with standard treatment for B-cell lymphoma, providing evidence-based support for the more efficient use of CAR-T cell immunotherapy. We conducted a comprehensive literature search of high-quality randomized controlled trials (RCTs) on CAR-T therapy for B-cell lymphoma in the following databases: Wanfang, Web of Science, CNKI, VIP database, and PubMed, up to February 2024. The outcome measures included objective remission rate (ORR), complete remission rate (CRR), and incidence of adverse reactions. Subgroup analysis was performed based on the differences in co-stimulatory domains. Meta-analysis was conducted using Review Manager 5.4 and Stata software. A total of five RCTs involving 1670 patients were included in this meta-analysis. The results showed that the CAR-T treatment group had significantly higher ORR (RR: 1.47, 95% CI 1.23-1.76, I2 = 80%, p < 0.0001), CRR (RR: 2.19, 95% CI 2.16-3.79, I2 = 93%, p = 0.005), cytokine release syndrome (CRS) incidence (RR: 34.51, 95% CI 2.27-523.78, I2 = 98%, p = 0.01), neurotoxicity (NT) incidence (RR: 6.00, 95% CI 1.82-19.75, I2 = 80%, p = 0.003), neutropenia incidence (RR: 1.39, 95% CI 1.02-1.88, I2 = 93%, p = 0.03), leukopenia incidence (RR: 1.39, 95% CI 1.04-1.87, I2 = 61%, p = 0.03), and headache incidence (RR: 1.56, 95% CI 1.25-1.95, I2 = 34%, p < 0.0001) compared to the standard treatment group. Subgroup analysis based on co-stimulatory domains revealed that the 4-1BB subgroup had higher incidences of CRR, CRS, NT and leukopenia than the CD28 subgroup; however, the CD28 subgroup exhibited higher ORR and neutropenia than the 4-1BB subgroup. CAR-T cell immunotherapy demonstrates superior efficacy compared to standard therapy in treating B-cell lymphoma. However, CAR-T treatment can lead to adverse reactions such as CRS and NT. Infusion of an appropriate dose of CAR-T cells (e.g., 100 × 106) may be a strategy to mitigate the risk of CRS and NT.

Inferior Overall Survival After Haploidentical Donor Lymphocyte Infusions in Relapsed Myeloid Neoplasms.

Allogeneic hematopoietic stem cell transplantation (HSCT) effectively treats high-risk myeloid neoplasms, but relapses post-HSCT, particularly in acute myeloid leukemia (AML) and myelodysplastic neoplasms (MDS), pose significant challenges. Donor lymphocyte infusion (DLI) has been utilized, but its effectiveness, especially in haploidentical settings, remains insufficiently clarified, and graft-versus-host disease (GvHD) poses a substantial risk. In this retrospective cohort study, 57 patients with AML or MDS who received DLI after allogeneic HSCT at our center from 2002 to 2023 were analyzed. Herein, only preemptively or therapeutically applied DLI were included, and endpoints included overall survival (OS), progression-free survival (PFS), and GvHD incidence post-DLI. Median OS after DLI was 517 days, with a 1-year OS of 62.5%. Factors associated with longer OS included patient age, HLA-identical donor, post-HSCT treatment naivety, and preemptive DLI indication. Haploidentical DLI was associated with inferior OS compared to HLA-identical DLI; however, PFS and GvHD incidence post-DLI did not differ significantly. Our study findings indicate that OS rate is inferior in patients with relapsed AML or MDS treated with haploidentical DLI in comparison to those who received HLA-identical DLI. Given the limitations of haploidentical DLI, alternative strategies, such as higher cell doses or combination treatment approaches, warrant further investigation.

Optimal infused CD34+ cell dose in multiple myeloma patients undergoing upfront autologous hematopoietic stem cell transplantation

Autologous transplantation remains the standard of care for eligible multiple myeloma (MM) patients, yet optimal CD34+ cell dose remains unclear. We conducted a retrospective study on MM patients undergoing upfront transplant between 2005 and 2021 and divided them into low (≤2.5 × 106 cells/kg) and high (>2.5 × 106 cells/kg) CD34+ dose groups. We included 2479 patients, 95 in the low CD34+ group and 2384 in the high CD34+ group. Patients in the low CD34+ group were older (63.2 vs 61.1 years, p = 0.013), more often had R-ISS III (19% vs 9%, p = 0.014), received plerixafor (60% vs 35%, p < 0.001) and transplanted after 2009 (88% vs 80%, p = 0.047). Time to neutrophil and platelet recovery was longer in the low CD34+ group. Median PFS and OS were lower in the low CD34+ group (31.6 vs. 43.6 months, p = 0.011 and 76.4 vs. 108.2 months, p < 0.001, respectively). Evaluation of incrementally higher CD34+ dose did not show significant improvement in survival at thresholds >2.5 × 106 cells/kg. Multivariable analysis affirmed that CD34+ >2.5 × 106 cells/kg was associated with better PFS (HR 0.71, p = 0.008) and OS (0.59, p < 0.001). After propensity score matching, a CD34+ dose >2.5 × 106 cells/kg remained a predictor of better OS (0.42, p < 0.001). In conclusion, CD34+ dose >2.5 × 106 cells/kg was associated with improved survival, without any additional benefit at incrementally higher doses.

Risk factors of pediatric steroid-induced ocular hypertension.

Steroid-induced ocular hypertension (SIOH) is a significant ocular complication of pediatric steroid administration. In this study, we analyzed the risk factors associated with pediatric SIOH. We retrospectively collected data from 78 children under 20 years of age who received systemic steroids during hospitalization. The data included age, gender, primary disease, intraocular pressure (IOP) before and one month after administration, total monthly steroid dose adjusted for body weight (BW), and one-month changes in red blood cell, white blood cell, and platelet counts. A multivariate analysis was used to identify risk factors related to steroid responsiveness. Thirty patients (38.5%) were classified as steroid responders, and 48 as non-responders. The median IOP during the first month of steroid treatment was 24.0 mmHg (IQR; 23.0-28.3) for responders and 15.0 mmHg (IQR; 12.3-18.0) for non-responders. The Generalized Estimating Equations analysis revealed that younger age, male sex, primary disease, increase the amount of white blood cell (WBC) and total steroid dose per BW in one month were independently associated variables. The receiver operating characteristic analysis also revealed that the cutoff values for age, total monthly steroid dose, the increase amount of WBC were 11.0 years, 40.7mg/kg and 3.40 × 10²/µl respectively. High-dose steroid administration, especially in male, younger patients, necessitates careful monitoring for IOP changes during treatment. WBC count also needs to be monitored during IOP follow-ups. What is known Steroid-induced ocular hypertension (SIOH) is one of the essential complicationsduring steroid administration,but onlylimited analyses have been performed in children. What is new A comprehensive analysis of multiple factors was performed that are predicted to be associated with pediatric SIOH from previous literature. Younger age, male sex, primary disease, increase the amount of WBC, and highertotal monthly steroid dose were extracted as risk factors of SIOH. This study can contribute to the prediction of cases in which ophthalmologic examinations are particularly important during systemic steroid administration in children.

Why are Higher CD34+ Cell Doses Associated with Improved Outcomes among Pediatric Patients Undergoing Autologous Hematopoietic Stem Cell Transplant for Central Nervous System Tumors – But Not for High-Risk Neuroblastoma?

Why are Higher CD34+ Cell Doses Associated with Improved Outcomes among Pediatric Patients Undergoing Autologous Hematopoietic Stem Cell Transplant for Central Nervous System Tumors – But Not for High-Risk Neuroblastoma?

Methylarginine targeting chimeras for lysosomal degradation of intracellular proteins.

A paradigm shift in drug development is the discovery of small molecules that harness the ubiquitin-proteasomal pathway to eliminate pathogenic proteins. Here we provide a modality for targeted protein degradation in lysosomes. We exploit an endogenous lysosomal pathway whereby protein arginine methyltransferases (PRMTs) initiate substrate degradation via arginine methylation. We developed a heterobifunctional small molecule, methylarginine targeting chimera (MrTAC), that recruits PRMT1 to a target protein for induced degradation in lysosomes. MrTAC compounds degraded substrates across cell lines, timescales and doses. MrTAC degradation required target protein methylation for subsequent lysosomal delivery via microautophagy. A library of MrTAC molecules exemplified the generality of MrTAC to degrade known targets and neo-substrates-glycogen synthase kinase 3β, MYC, bromodomain-containing protein 4 and histone deacetylase 6. MrTAC selectively degraded target proteins and drove biological loss-of-function phenotypes in survival, transcription and proliferation. Collectively, MrTAC demonstrates the utility of endogenous lysosomal proteolysis in the generation of a new class of small molecule degraders.

Application of phase space file secondary computation method in cell dose distribution

Phase space files can store the particle information in one or more planes of radiation particles simulated by the Monte Carlo (MC) method. The secondary calculation method based on phase space files is commonly used to improve the efficiency of MC simulations. However, it is still unclear whether phase space files are applicable for microdosimetric evaluations. In this study, voxel-type and mesh-type monolayer cell population models of different sizes were constructed, and phase space files of secondary electrons generated by photons with different initial energies were obtained using the MC software -- PHITS. The overall average dose caused by the secondary electron phase space files in the region of interest and their microdosimetric distribution within cells were calculated and compared with the results caused by the initial photons under the same geometric conditions. The results showed that the adoption of secondary electron phase space files had almost no impact on the evaluation of macroscopic average dose, with deviations lower than 3% compared to the overall dose caused by the initial photons in the Petri dish. For microdosimetric distributions of the voxel-type model and the two different morphologies of mesh-type cell models, with a macroscopic accumulated dose of 1 mGy, the relative deviation of the cell dose distribution generated by the initial photons and the phase space files was below 10% and the total computation time of phase space files was below 2% of initial photon's. For accumulated doses of 10, 50, and 100 mGy, the relative deviation of the cell nucleus specific energy obtained by secondary electrons and initial photons was greater than 10%. As the size of the culture dish increased, the differences in cell dose distributions also increased, with the root mean square error (RMSE) and coefficient of variation (Cv) of dose distributions both exceeding 30%. In conclusion, this study assessed the effectiveness of the secondary calculation method utilizing phase space files for dose evaluation at the cellular scale. This research offers essential technical support and theoretical foundations for the utilization of this approach in microdosimetric investigations at the cellular level.

High dose chemotherapy with autologous stem cell rescue in children and young adults with high-risk Ewing sarcoma: A single institute experience in Taiwan.

A combination treatment of surgery, chemotherapy, and radiotherapy can improve the survivals of pediatric patients with Ewing sarcoma (ES). However, prognosis remains poor for patients with metastatic disease at diagnosis or recurrence. Other high-risk (HR) features include large tumor burden, tumors of the axial skeleton and poor histologic response. Several studies have documented high dose chemotherapy with autologous stem cell rescue (HDC-ASCR) to be effective in such patients. In this retrospective study, we present the results of HDC-ASCR for high-risk Ewing sarcoma in children and young adults in a single institute. From March 2004 to March 2021, patients with ES, Ewing-like sarcoma, or round cell sarcoma received HDC-ASCR as part of treatment were included. The patients' characteristics, disease status, stem cell dose, engraftment status, post-transplant complications, and outcomes were analyzed. Twenty patients receiving HDC-ASCR at complete response (n = 6), partial response (n = 13), and stable disease (n = 1) were enrolled. The male to female ratio was 11:9. Median age at diagnosis and transplant was 15.6 years old (range: 3.3-28.9) and 16.2 (range: 4.2-29.9), respectively. The conditioning regimens included ifosfamide-based in two and melphalan-based in 19. All patients achieved successful engraftment without tansplant-related mortality. The 5-year progression-free and overall survival (OS) rate were 35% and 54.5%, respectively. The causes of death (n = 8) were all contributed to disease progression. Patients in the complete response group or with localized HRES exhibited a higher 5-year OS (p = 0.047 and 0.05, respectively). Compared to the historical cohort without HDC-ASCR as part of primary treatment, the current cohort had a significantly better 5-year OS (p = 0.018). HDC-ASCR seems promising as an alternative treatment for HRES in improving OS in this retrospective study with limited case number.

The Therapeutic Use of Dental Mesenchymal Stem Cells in Human Clinical Trials

Mesenchymal stem cells (MSCs), characterized by their undifferentiated and multipotent nature, can be derived from various sources, including bone marrow, adipose, and dental tissues. Among these, dental MSCs (DSCs) exhibit universal MSC characteristics and are attracting considerable attention for regenerating oral and craniofacial tissues. This review provides a contemporary overview of recently published clinical studies using DSCs for various orodental and maxillofacial regenerative applications, including bone, periodontal, and endodontic regeneration. It also explores the utilization of DSCs in treating systemic conditions, exemplified by their application in managing conditions such as COVID-19 and osteoarthritis. The available evidence underscores the potential of DSCs and their secretome as efficacious tools in regenerative medicine for both dental and nondental clinical applications, supporting the continued promise of stem cell–based therapies. It is nevertheless evident that there are a number of important challenges that restrict the widespread utilization of DSCs, namely, difficulty in standardizing autologous preparations, insufficient cell surface marker characterization, high production costs, and regulatory compliance requirements. Further, the unique requirements of dental applications, especially complex structures such as the periodontium, where temporospatial control over the healing process is required, necessitate the combination of stem cells with appropriate scaffolds according to the principles of tissue engineering. There is currently insufficient evidence to support the clinical translation of DSCs into clinical practice, and phase 3 clinical trials with standardized protocols for cell sourcing, propagation, dosing, and delivery are required to move the field forward. In summary, this review provides a contemporary overview of the evolving landscape of stem cell therapy, offering insights into the latest developments and trends as well as the challenges that need to be addressed for the widespread application of DSC-based cell therapies.

A Pilot Study of UM171-Expanded Cord Blood Grafts for Tandem Auto/Allogeneic Hematopoietic Cell Transplant in High and Ultra-High-Risk Myeloma Patients

Multiple myeloma (MM) remains associated with a poor outcome, particularly in patients with advanced disease and high-risk (HR) cytogenetics. To date, the only curative treatment is allogeneic (allo) hematopoietic cell transplantation (HCT), but high incidences of graft versus host disease (GVHD), non-relapse mortality (NRM) and disease progression remain important obstacles. Cord blood (CB) transplantation has been associated with low rates of relapse and chronic (c) GVHD, but its use has declined because of high incidences of infections, severe acute GVHD and high NRM. In other hematologic malignancies, UM171-expanded CB transplants have led to improved outcomes, allowing for the selection of smaller, better HLA-matched units. We aimed to investigate the safety and feasibility of single UM171-expanded single CB unit transplantation in frontline tandem auto/allo HCT for HR/ultra-HR MM patients. Newly diagnosed MM patients ≤ 65 years with an ISS stage II/III and del17p, t4,14, t14,16, t14,20, del1p or +1q, R-ISS 3, ≥ 2 cytogenetic abnormalities, or plasma cell leukemia without a sibling donor and availability of a 5-7/8 matched CB graft with ≥ 0.5 x 105 CD34+/kg and ≥ 1.5 x 107 TNCs/kg were eligible to this phase I/II prospective study (ClinicalTrials.gov NCT03441958). After induction and autologous HCT, patients received a reduced intensity conditioning regimen and were infused with 7-day UM171-expanded CD34+ cells, along with the lymphocytes contained in the CD34-negative fraction. The primary endpoints were feasibility of UM171 expansion, safety, kinetics of engraftment, incidences and maximum grades of acute and cGVHD at 1 and 2 years, assessment of measurable residual disease (MRD) and quality of life (QoL). Between 05/2018 and 11/2021, 20 patients were enrolled. One patient had an unsuccessful CB expansion with UM171, leaving 19 patients with a median age of 56 years. Median CD34+ cell dose infused after expansion was 4.62 x 106/kg (range: 0.79-5.76). Median times to achieve absolute neutrophil counts of 0.1 and 0.5 x 109/L were D+6 and D+10.5; median time to reach ≥ 20 x 109/L platelets was D+36. Full donor chimerism was achieved in all cell lineages by D+120 in recipients of reduced intensity conditioning. Cumulative incidences of grade II-IV, grade III-IV acute GVHD and moderate/severe cGVHD at 12 months were 68.4% (95% CI: 46-90), 5.3% (95% CI: 0-16%), and 10.5% (95% CI: 0-25%), respectively. With a median follow-up of 2.9 years (range: 0.46-5.3), cumulative incidences of relapse, PFS, OS and NRM at 3 years were 36.8% (95% CI: 14-59), 47.4% (95% CI: 29-76), 68.4% (95% CI: 50-93) and 15.8% (95%CI: 0-33), respectively. Median time to complete immunosuppression discontinuation was D+238. No unexpected adverse events were observed. Only one of 7 patients alive at 2 years with negative MRD at transplant has relapsed. Non-relapsing patients had a QoL after transplant similar to the general population. UM171-expanded CB transplant in HR/ultra-HR myeloma patients is feasible and allows the use of single CB units with a low risk of cGVHD. Patients with negative pre-transplant MRD might benefit most from a UM171-expanded CB transplant.

Extensive immunophenotypic sub-population analysis of StemRegenin1 expanded haematopoietic stem/progenitor cells

BackgroundEx vivo haematopoietic stem/progenitor cell (HSPCs) expansion constitutes an important area of research, and has the potential to improve access to umbilical cord blood (UCB) as a source of stem cells for haematopoietic stem cell transplantation (HSCT). The ability to improve stem cell dose and thereby reduce delayed engraftment times, which has plagued the use of UCB as a stem cell source since inception, is a recognised advantage. The extent to which cluster of differentiation (CD)34 sub-populations are affected by expansion with StemRegenin1 (SR1), and whether a particular subtype may account for better engraftment than others, is currently unknown. The purpose of this study was to determine the impact of SR1-induced HSPC expansion on CD34+ immunophenotypic subsets and gene expression profiles.MethodsUCB-derived CD34+ HSPCs were characterised before (D0) and after expansion (D7) with SR1 using an extensive immunophenotypic panel. In addition, gene expression was assessed and differentially expressed genes were categorised into biological processes.ResultsA dose-dependent increase in the number of CD34+ HSPCs was observed with SR1 treatment, and unbiased and extensive HSPC immunophenotyping proved to be a powerful tool in identifying unique sub-populations within the HSPC repertoire. In this regard, we found that SR1 promotes the emergence of HSPC subsets which may aid engraftment post expansion. In addition, we observed that SR1 has a minimal effect on the transcriptome of 7-day expanded CD34+ HSPCs when compared to cells expanded without SR1, with only two genes being downregulated in the former.ConclusionThis study revealed that SR1 selects for potentially novel immunophenotypic HSPC subsets post expansion and has a minimal effect on the transcriptome of 7-day expanded HSPCs when compared to vehicle controls. Whether these distinct immunophenotypic sub-populations possess greater engraftment capacity remains to be tested in animal models.

EP465 - Transfusion Associated Circulatory Overload (TACO) Audit - A prospective analysis of adherence to standards ensuring safe transfusions

Abstract Aims TACO is defined as acute or worsening respiratory compromise during or up to 12 hours of transfusion, with additional features including cardiovascular system changes not explained by the patient’s underlying medical condition. In the UK, TACO remains a major cause of Morbidity in surgical post operative patients. The aim of this audit was to assess whether the current trust transfusion practices are synchronous with the NICE guidelines and SHOT recommendations. Methods We reviewed 27 incidences of transfusion during the whole month in acute general surgical ward. Patient’s notes, trust intranet and EPMA were used for data collection. The adherence to Ng24 as well as latest SHOT recommendations was checked. Following standards were taken into account: A formal pre-transfusion risk assessment for transfusion-associated circulatory overload (TACO) should be undertaken for all patients receiving blood transfusion and mitigating actions taken. (Serious hazards of transfusion SHOT recommendation) Patients who develop respiratory distress during or up to 24 hours following transfusion where transfusion is suspected to be the cause must be reported to SHOT. A structured incident review should be undertaken for every case of TACO. Weight-adjusted red cell dosing should be used. (NICE Guidelines Ng24) Result TACO assessment checklist was only completed for 15% of transfusions (compared to 35% nationally) while mitigation actions were only considered for 4% of patients. There appeared discordance among junior doctors regarding TACO Management. Conclusions Interventions like teaching sessions, information leaflets and posters, presentation for induction pack and liaison with Transfusion practitioner team to modify transfusion pathway significantly reduced inconsistencies regarding safe transfusions and immensely improved patient management.

Fratricide-resistant CD7-CAR T cells in T-ALL.

T cell acute lymphoblastic leukemia (T-ALL) is difficult to treat when it relapses after therapy or is chemoresistant; the prognosis of patients with relapsed or refractory T-ALL is generally poor. We report a case series of 17 such patients who received autologous chimeric antigen receptor (CAR) T cells expressing an anti-CD7 CAR and an anti-CD7 protein expression blocker (PEBL), which prevented CAR T cell fratricide. Despite high leukemic burden and low CAR T cell dosing, 16 of the 17 patients attained minimal residual disease-negative complete remission within 1 month. The remaining patient had CD7- T-ALL cells before infusion, which persisted after infusion. Toxicities were mild: cytokine release syndrome grade 1 in ten patients and grade 2 in three patients; immune effector cell-associated neurotoxicity syndrome grade 1 in two patients. Eleven patients remained relapse-free (median follow-up, 15 months), including all nine patients who received an allotransplant. The first patient is in remission 55 months after infusion without further chemotherapy or transplantation; circulating CAR T cells were detectable for 2 years. T cells regenerating after lymphodepletion lacked CD7 expression, were polyclonal and responded to SARS-CoV-2 vaccination; CD7+ immune cells reemerged concomitantly with CAR T cell disappearance. In conclusion, autologous anti-CD7 PEBL-CAR T cells have powerful antileukemic activity and are potentially an effective option for the treatment of T-ALL.

Low-dose orthotopic cancer implantation permits measurement of longitudinal functional changes associated with cachexia.

Progressive functional decline is a key element of cancer-associated cachexia. Major barriers to translating preclinical therapies into the clinic include lack of cancer models that accurately mimic functional decline, which develops over time, and use of nonspecific measures, like grip strength, as surrogates for physical function. In this study, we aimed to extend the survival and longevity of a cancer model, to investigate cachexia-related function at the basic science level. Survival extension studies were performed by testing multiple cell lines, dilutions, and vehicle-types in orthotopic implantation of K-rasLSL.G12D/+; Trp53R172H/+; Pdx-1-Cre (KPC)-derived cells. One hundred twenty-eight animals in this new model were assessed for cachexia syndrome phenotype using a battery of anatomical, biochemical, and behavioral techniques. We extended the survival of the KPC orthotopic model to 8-9 wk postimplantation using a relatively low 100-cell dose of DT10022 KPC cells (P < 0.001). In this low-dose orthotopic (LO) model, progressive muscle wasting was detected in parallel to systemic inflammation; skeletal muscle atrophy at the fiber level was detected as early as 3 wk postimplantation compared with controls (P < 0.001). Gait speed in LO animals declined as early as 2 wk postimplantation, whereas grip strength change was a late event. Principal component and regression analyses revealed distinct cachectic and noncachectic animal populations, which we leveraged to show that the gait speed decline was specific to cachexia (P < 0.01), whereas grip strength decline was not (P = 0.19). Gait speed represents an accurate surrogate for cachexia-related physical function as opposed to grip strength.NEW & NOTEWORTHY Previous studies of cancer-induced cachexia have been confounded by the relatively rapid death of animal subjects. Using a lower dose of cancer cells in combination with a battery of behavioral, structural, histological, and biochemical techniques, we show that gait speed is actually the best indicator of functional decline due to cachexia. Future studies are required to define the underlying physiological basis of these findings.

A comparative review of Aphexda and Mozobil for mobilization prior to stem cell collection.

High-dose chemotherapy followed by autologous hematopoietic stem cell transplantation is the standard of care for eligible patients with newly diagnosed multiple myeloma leading to prolonged progression free and overall survival. Successful engraftment following hematopoietic stem cell infusion requires adequate stem cell doses. Current mobilization regimens include granulocyte colony-stimulating factor (G-CSF) with or without plerixafor. Motixafortide is a recently approved agent that can be used in combination with G-CSF for mobilization. In the absence of any head-to-head trials comparing the two products, this article aims to outline the similarities and differences of these two agents. Though moxitafortide has a more favorable pharmacokinetic profile in comparison to plerixafor, in clinical trials, the agents demonstrated similar efficacy. In addition, the use of motixafortide in clinical practice may be limited by product cost as well as administration and monitoring requirements.