Cellular strategies to induce immune tolerance after liver transplantation: Clinical perspectives

Liver transplantation (LT) has become the most efficient treatment for pediatric and adult end-stage liver disease and the survival time after transplantation is becoming longer due to the development of surgical techniques and perioperative management. However, long-term side-effects of immunosuppressants, like infection, metabolic disorders and malignant tumor are gaining more attention. Immune tolerance is the status in which LT recipients no longer need to take any immunosuppressants, but the liver function and intrahepatic histology maintain normal. The approaches to achieve immune tolerance after transplantation include spontaneous, operational and induced tolerance. The first two means require no specific intervention but withdrawing immunosuppressant gradually during follow-up. No clinical factors or biomarkers so far could accurately predict who are suitable for immunosuppressant withdraw after transplantation. With the understanding to the underlying mechanisms of immune tolerance, many strategies have been developed to induce tolerance in LT recipients. Cellular strategy is one of the most promising methods for immune tolerance induction, including chimerism induced by hematopoietic stem cells and adoptive transfer of regulatory immune cells. The safety and efficacy of various cell products have been evaluated by prospective preclinical and clinical trials, while obstacles still exist before translating into clinical practice. Here, we will summarize the latest perspectives and concerns on the clinical application of cellular strategies in LT recipients.

Extracorporeal photopheresis reduces inflammation and joint damage in a rheumatoid arthritis murine model

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disease characterized by inflammatory reactions and tissue damage in the joints. Long-term drug use in clinical practice is often accompanied by adverse reactions. Extracorporeal photopheresis (ECP) is an immunomodulatory therapy with few side effects, offering a potential and safe therapeutic alternative for RA through the induction of immune tolerance. This study aimed to investigate the therapeutic effects of ECP on RA using a collagen-induced arthritis (CIA) murine model, as well as to explore its immunomodulatory effects in vivo. Additionally, particular attention was given to the significant role of monocytes during the ECP process.

METHODS

A murine model of rheumatoid arthritis was established by administering two injections of bovine type II collagen to DBA/1J mice. ECP, ECP-MD (mononuclear cells were depleted during the ECP), MTX, and PBS treatment were applied to the CIA mice. During the treatment process, clinical scores and body weight changes of CIA mice were closely monitored. After six treatment sessions, micro-CT images of the hind paws from live mice were captured. Ankle joints and paws of the mice were collected and processed for histological evaluation. Spleen samples were collected to measure the Th17/Treg cells ratio, and serum samples were collected to assess cytokine and anti-type II collagen IgG levels. Monocytes and dendritic cells populations before and after ECP in vitro were detected by flow cytometry.

RESULT

ECP therapy significantly attenuated the progression of CIA, alleviated the severity of clinical symptoms in CIA mice and effectively suppressed synovial hyperplasia, inflammation, and cartilage damage. There was an expansion in the percentage of CD3 + CD4 + CD25 + FoxP3 + Tregs and a decrease in CD3 + CD4 + IL17A + Th17 cells in vivo. Furthermore, ECP reduced the serum levels of pro-inflammatory cytokines IL-6 (53.47 ± 7.074 pg/mL vs 5.142 ± 1.779 pg/mL, P < 0.05) and IL-17A (3.077 ± 0.401 pg/mL vs 0.238 ± 0.082 pg/mlL, P < 0.0001) compared with PBS. Interestingly, the depletion of monocytes during the ECP process did not lead to any improvement in clinical symptoms or histological scores in CIA mice. Moreover, the imbalance in the Th17/Treg cells ratio became even more pronounced, accompanied by an augmented secretion of pro-inflammatory cytokines IL-6 and IL-17A. In vitro, compared with cells without ECP treatment, the proportion of CD11b + cells were significantly reduced (P < 0.01), the proportion of CD11c + cells were significantly elevated (P < 0.001) 24 h after ECP treatment. Additionally, the expression of MHC II (P < 0.0001), CD80 (P < 0.01), and CD86 (P < 0.001) was downregulated in CD11c + cells 24 h after ECP treatment.

CONCLUSION

Our study demonstrates that ECP exhibits a therapeutic effect comparable to conventional therapy in CIA mice, and the protective mechanisms of ECP against RA involve Th17/Treg cells ratio, which result in decreased IL-6 and IL-17A. Notably, monocytes derived from CIA mice are an indispensable part to the efficacy of ECP treatment, and the proportion of monocytes decreased and the proportion of tolerogenic dendritic cells increased after ECP treatment in vitro.

SOHO State of the Art Updates and Next Questions Updates on Building Your CAR-T Cell Program

Chimeric antigen receptor T-cell (CAR-T) therapy has significantly impacted treatment algorithms and clinical outcomes for a variety of patients with hematologic malignancies over the past decade. The field of cellular immunotherapy is currently experiencing a rapid expansion of the number of patients eligible for CAR-T therapies as approvals are being seen in earlier lines of therapy. With the expanded patients eligible for these therapies, more treatment centers will be necessary to keep up with demand. Building a cellular therapy program can be a daunting task, and therefore, we present our experience with building a clinical cellular therapy program.

Safety and efficacy of anti-BCMA CAR-T cell therapy in older adults with multiple myeloma: A systematic review and meta-analysis

INTRODUCTION

Anti-B-cell maturation antigen (BCMA) chimeric antigen receptor T-cell (CAR-T) therapy is transforming the care of patients with relapsed/refractory multiple myeloma (MM). Unfortunately, despite being a disease of older adults these patients remain under-represented in most pivotal clinical trials. We performed a systematic review and proportion meta-analysis of prospective clinical trials and observational studies of anti-BCMA CAR-T therapy in patients with MM with the aim to determine the efficacy and safety of this therapy in older adults (≥65 years).

MATERIALS AND METHODS

We searched the Pubmed, Scopus, Web of Science (WOS), Ovid, Embase, CENTRAL, and CINAHL databases through September 9, 2022 and abstracts from the American Society of Hematology (ASH) Annual Meeting 2022. Primary outcome measures included overall response rate (ORR), rates of cytokine release syndrome (CRS), and immune cell-effector-associated neurotoxicity syndrome (ICANS). study was registered with PROSPERO (study number: CRD42022334287).

RESULTS

After screening 2218 references, 14 studies were included for data extraction, with a total of 558 patients, 26.2% (n = 146) of whom were older adults. The pooled ORR amongst this population was 93%, which was comparable to the ORR of 86% amongst younger patients. In older adults, the rates of CRS (any grade) and grade ≥ 3 were 95% and 21%, respectively. For younger patients, the pooled rate of CRS (any grade) and grade ≥ 3 CRS was 91% and 20%, respectively. The rate of ICANS (any grade) in older adults was 15%, which was higher than that observed in those <65 years.

CONCLUSION

Older adults experience comparable outcomes to younger patients with anti-BCMA CAR-T therapy, albeit with numerically higher rates of neurotoxicity.

Schisandrin B promotes hepatic differentiation from human umbilical cord mesenchymal stem cells

Human umbilical cord mesenchymal stem cells (UC-MSCs)-derived hepatocyte-like cells (HLCs) have shown great promise in the treatment of liver diseases. However, most current induction protocols yield hepatocyte-like cells with limited function as compared with primary hepatocytes. Schisandrin B (Sch B) is one of the main components of Schisandra chinensis, which can prevent fibrosis progression and promote liver cell regeneration. Herein, we investigated the effects of Sch B on hepatic differentiation of UC-MSCs. We found that treatment with 10 μM Sch B from the second stage of the differentiation process increased hepatic marker levels and hepatic function. Additionally, RNA-seq analysis revealed that Sch B promoted hepatic differentiation via activating the JAK2/STAT3 pathway. When transplanted HLCs into mice with CCL4-induced liver fibrosis, Sch B-treated HLCs exhibited significant therapeutic effects. This study provides an optimized hepatic differentiation protocol for UC-MSCs based on Sch B, yielding functioning cells for liver disease treatment.

Safety and Toxicity Profiles of CAR T Cell Therapy in Non-Hodgkin Lymphoma: A Systematic Review and Meta-Analysis

BACKGROUND

The application of CD19-directed chimeric antigen receptor T (CAR T) cell therapy has improved outcomes for thousands of patients with non-Hodgkin B cell lymphoma (NHL). The toxicities associated with various CAR T cell products, however, can be severe and difficult to anticipate.

METHODS

In this systematic review and meta-analysis, we set out to determine whether there are measurable differences in common toxicities, including cytokine release syndrome (CRS), immune effector cell associated neurotoxicity syndrome (ICANS), cytopenias, and infections, between CAR T products that are commercially available for the treatment of NHL.

RESULTS

After a stringent study selection process, we used a cohort of 1364 patients enrolled in 15 prospective clinical trials investigating the use of axicabtagene ciloleucel (axi-cel), lisocabtagene maraleucel (liso-cel), and tisagenlecleucel (tisa-cel). We found that the rates of CRS and ICANS were significantly higher with axi-cel as compared to both liso-cel and tisa-cel. Conversely, we demonstrated that rates of all-grade and severe neutropenia were significantly greater with liso-cel. Febrile neutropenia and all-grade infection rates did not differ significantly between products though rates of severe infection were increased with axi-cel.

CONCLUSIONS

Overall, this study serves as the first to delineate toxicity profiles associated with various available CAR T products. By better understanding associated toxicities, it may become possible to tailor therapies towards individual patients and anticipate the development of toxicities at earlier stages.

The cross talk between type II diabetic microenvironment and the regenerative capacities of human adipose tissue-derived pericytes: a promising cell therapy

BACKGROUND

Pericytes (PCs) are multipotent contractile cells that wrap around the endothelial cells (ECs) to maintain the blood vessel's functionality and integrity. The hyperglycemia associated with Type 2 diabetes mellitus (T2DM) was shown to impair the function of PCs and increase the risk of diabetes complications. In this study, we aimed to investigate the deleterious effect of the diabetic microenvironment on the regenerative capacities of human PCs.

METHODS

PCs isolated from human adipose tissue were cultured in the presence or absence of serum collected from diabetic patients. The functionality of PCs was analyzed after 6, 14, and 30 days.

RESULTS

Microscopic examination of PCs cultured in DS (DS-PCs) showed increased aggregate formation and altered surface topography with hyperbolic invaginations. Compared to PCs cultured in normal serum (NS-PCs), DS-PCs showed more fragmented mitochondria and thicker nuclear membrane. DS caused impaired angiogenic differentiation of PCs as confirmed by tube formation, decreased VEGF-A and IGF-1 gene expression, upregulated TSP1, PF4, actin-related protein 2/3 complex, and downregulated COL21A1 protein expression. These cells suffered more pronounced apoptosis and showed higher expression of Clic4, apoptosis facilitator BCl-2-like protein, serine/threonine protein phosphatase, and caspase-7 proteins. DS-PCs showed dysregulated DNA repair genes CDKN1A, SIRT1, XRCC5 TERF2, and upregulation of the pro-inflammatory genes ICAM1, IL-6, and TNF-α. Further, DS-treated cells also showed disruption in the expression of the focal adhesion and binding proteins TSP1, TGF-β, fibronectin, and PCDH7. Interestingly, DS-PCs showed resistance mechanisms upon exposure to diabetic microenvironment by maintaining the intracellular reactive oxygen species (ROS) level and upregulation of extracellular matrix (ECM) organizing proteins as vinculin, IQGAP1, and tubulin beta chain.

CONCLUSION

These data showed that the diabetic microenvironment exert a deleterious effect on the regenerative capacities of human adipose tissue-derived PCs, and may thus have possible implications on the vascular complications of T2DM. Nevertheless, PCs have shown remarkable protective mechanisms when initially exposed to DS and thus they could provide a promising cellular therapy for T2DM.

Targeted Therapies in Pediatric Acute Myeloid Leukemia - Evolving Therapeutic Landscape

Acute myeloid leukemia (AML) accounts for 25% of all leukemia diagnosis and is characterized by distinct cytogenetic and molecular profile. Advances in the understanding of the causative driver mutations, risk-based therapy and better supportive care have led to an overall improvement in survival with frontline therapy. Despite these improvements, a significant number fail either because of primary refractory disease to the conventional 7+3 combination of anthracyclines and cytosine arabinoside (Cytarabine; Ara-C) or experience relapse post remission. Salvage therapy is complicated by the cardiotoxicity driven limitations on the reuse of anthracyclines and development of resistance to cytarabine. In this chapter authors will review the recent studies with targeted agents for refractory AML including targets for immunotherapeutic strategies.

INSPIRED Symposium Part 4B: Chimeric Antigen Receptor T Cell Correlative Studies-Established Findings and Future Priorities

Chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of B cell malignancies, with multiple CAR T cell products approved for numerous indications by regulatory agencies worldwide. However, significant work remains to be done to enhance these treatments. In March 2023, a group of experts in CAR T cell therapy assembled at the National Institutes of Health in Bethesda, Maryland at the Insights in Pediatric CAR T Cell Immunotherapy: Recent Advances and Future Directions (INSPIRED) Symposium to identify key areas for research for the coming years. In session 4B, correlative studies to be incorporated into future clinical trials and real-world settings were discussed. Active areas of research identified included (1) optimizing CAR T cell product manufacturing; (2) ensuring adequate lymphodepletion prior to CAR T cell administration; (3) overcoming immunoregulatory cells and tumor stroma present in the tumor microenvironment, particularly in solid tumors; (4) understanding tumor intrinsic properties that lead to CAR T cell immunotherapy resistance; and (5) uncovering biomarkers predictive of treatment resistance, treatment durability, or immune-related adverse events. Here we review the results of previously published clinical trials and real-world studies to summarize what is currently known about each of these topics. We then outline priorities for future research that we believe will be important for improving our understanding of CAR T cell therapy and ultimately leading to better outcomes for patients.

Chimeric Antigen Receptor T-Cell Therapy in the Outpatient Setting: An Expert Panel Opinion from the American Society for Transplantation and Cellular Therapy

The first series of chimeric antigen receptor T (CAR-T) cell therapy products were approved in 2017 to 2019 and have shown remarkable efficacy in both clinical trials and the real-world setting, but at the cost of prolonged patient hospitalization. As the toxicity management protocols were refined, the concept of cellular therapy administered in the outpatient setting gained steam, and single institutions began to perform certain aspects of CAR-T monitoring in the outpatient setting for select patients. However, there are many considerations for a successful outpatient program. In anticipation of increasing use of CAR-T-cell therapy in the outpatient setting as a mechanism to overcome frequent hospital bed shortages and high cost of inpatient care, the American Society for Transplantation and Cellular Therapy convened a group of experts in hematology, oncology, and cellular therapy to provide a comprehensive review of the existing publications on outpatient CAR-T cell therapy, discuss selected ongoing clinical trials of outpatient CAR-T, and describe strategies to optimize safety without compromising efficacy for patients treated and monitored in the outpatient setting.

Results from a Phase 1 Study of ACTR707 in Combination with Rituximab in Patients with Relapsed or Refractory CD20+ B Cell Lymphoma

The antibody-coupled T cell receptor (ACTR) platform is an autologous engineered T cell therapy combining the cell-killing ability of T cells and the tumor-targeting ability of coadministered antibodies. Activation of the T cell product ACTR707 is dependent on the engagement of antibody bound to target cells via the CD16 domain of the chimeric receptor (CD16V-CD28-CD3ζ). ACTR707 in combination with the anti-CD20 monoclonal antibody rituximab was evaluated in the ATTCK-20-03 study, a multisite, single-arm, open-label phase I trial in B cell non-Hodgkin lymphoma (NHL). The primary objectives of this study were to evaluate the safety of the combination of ACTR707 and rituximab and to determine a recommended phase 2 dose (RP2D). Secondary objectives included evaluation of antitumor activity and ACTR T cell persistence. The study design included an ACTR707 cell dose escalation phase and an expansion phase at the RP2D. Escalating dose levels of ACTR707 in combination with rituximab were explored in 5 dose cohorts, with 25 subjects receiving study treatment. Subjects received lymphodepleting chemotherapy (cyclophosphamide 400 mg/m2/day and fludarabine 30 mg/m2/day) for 3 days, followed by rituximab 375 mg/m2 and, 24 to 48 hours later, a single dose of ACTR707. Additional doses of rituximab were administered every 3 weeks until disease progression, unacceptable toxicity, or investigator decision. Blood samples were collected at various time points to assess levels of rituximab, cytokines, inflammatory markers, and ACTR707 T cells. The overall response rate of ACTR707 plus rituximab was 56% (14 of 25) across all dose levels. Ten subjects (40.0%) achieved a complete response, with the longest duration of 586 days (range, 85 to 586 days), and 4 subjects (16.0%) experienced a partial response, with the longest duration of 130 days (range, 44 to 130 days). Only 1 case of cytokine release syndrome (grade 2) and no events of neurotoxicity were reported. There were no dose-limiting toxicities or events leading to death. ACTR707 plus rituximab resulted in only 1 adverse event (neutropenia), leading to study discontinuation of rituximab. The ATTCK-20-03 trial serves as proof of principle regarding the ACTR approach that potentially could be used with other antibodies targeting other markers in other malignancies. Although the ACTR707 program has been discontinued, these results may support other programs in the use of similar novel approaches of antibody-coupled T cell activation.

[Role of advanced practice nurse within a cellular therapy unit: Guidelines from the Francophone Society of Bone Marrow Transplantation and cellular therapy (SFGM-TC)]

Like the "nurse practitioner" in Anglo-Saxon countries, the French health authority validated on January 2016 the creation of an intermediate grade called advanced practice nurse (APN). They are authorized to carry out an assessment of the person's state of health, through a complete clinical examination. They can also prescribe additional examinations necessary for the monitoring of the pathology, and carry out certain acts for diagnostic and/or therapeutic purposes. Given the specificities of cellular therapy patients, the content of university professional training doesn't seem sufficient to assure an optimal management by the APN of these patients. The Francophone society of bone marrow transplantation and cellular therapy (SFGM-TC) had already published two works regarding what was initially called "the transfer of skills" between doctors and nurses in the follow-up of transplant patients. In the same way, this workshop attempts to address the question of the place of APNs in the management of patients undergoing cellular therapy treatment. Beyond a delegation of tasks as proposed by the cooperation protocols, this workshop produces recommendations to allow an autonomous activity of the IPA in the follow-up of these patients, in close collaboration with the medical team.

Therapy-induced normal tissue damage promotes breast cancer metastasis

Disseminated tumor cells frequently exhibit a period of dormancy, rendering them chemotherapy insensitive; conversely, the systemic delivery of chemotherapies can result in normal tissue damage. Using multiple mouse and human breast cancer models, we demonstrate that prior chemotherapy administration enhances metastatic colonization and outgrowth. In vitro, chemotherapy-treated fibroblasts display a pro-tumorigenic senescence-associated secretory phenotype (SASP) and are effectively eliminated by targeting the anti-apoptotic protein BCL-xL. In vivo, chemotherapy treatment induces SASP expression in normal tissues; however, the accumulation of senescent cells is limited, and BCL-xL inhibitors are unable to reduce chemotherapy-enhanced metastasis. This likely reflects that chemotherapy-exposed stromal cells do not enter a BCL-xL-dependent phenotype or switch their dependency to other anti-apoptotic BCL-2 family members. This study highlights the role of the metastatic microenvironment in controlling outgrowth of disseminated tumor cells and the need to identify additional approaches to limit the pro-tumorigenic effects of therapy-induced normal tissue damage.

Transforming CLL management with immunotherapy: Investigating the potential of CAR T-cells and bispecific antibodies

Immunotherapies, such as chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies or T-cell engagers, have revolutionized the treatment landscape for various B-cell malignancies, including B-acute lymphoblastic leukemia and many non-Hodgkin lymphomas. Despite their significant impact on these malignancies, their application in chronic lymphocytic leukemia (CLL) management is still largely under investigation. Although the initial success of CD19-directed CAR T-cell therapy was observed in 3 multiply relapsed CLL patients, with 2 of them surviving over 10 years without relapse, recent CAR T-cell therapy trials in CLL have shown reduced response rates compared to their efficacy in other B-cell malignancies. One of the challenges with using immunotherapy in CLL is the compromised T-cell fitness from persistent CLL-related antigenic stimulation, and an immunosuppressive tumor microenvironment (TME). These challenges underscore a critical gap in therapeutic options for CLL patients intolerant or resistant to current therapies, emphasizing the imperative role of effective immunotherapy. Encouragingly, innovative strategies are emerging to overcome these challenges. These include integrating synergistic agents like ibrutinib to enhance CAR T-cell function and persistence and engineering newer CAR T-cell constructs targeting diverse antigens or employing dual-targeting approaches. Bispecific antibodies are an exciting "off-the-shelf" prospect for these patients, with their investigation in CLL currently entering the realm of clinical trials. Additionally, the development of allogeneic CAR T-cells and natural killer (NK) cells from healthy donors presents a promising solution to address the diminished T-cell fitness observed in CLL patients. This comprehensive review delves into the latest insights regarding the role of immunotherapy in CLL, the complex landscape of resistance mechanisms, and a spectrum of innovative approaches to surmount therapeutic challenges.

Efficacy of transplantation of lipoaspired mesenchymal stem cells in the treatment of chronic rotator cuff tears. Experimental model in rats

BACKGROUND AND AIM

Rotator cuff tears emerge in approximately 30% of the population over 60 years of age. Arthroscopic surgical treatment of these lesions is the treatment of choice, however, despite the improved repair techniques, the rate of re-tears ranges between 11 and 94%. Therefore, researchers seek to improve the biological healing process through the use of different alternatives such as mesenchymal stem cells (MSCs). Our objective is to evaluate the efficacy of a Cellular Therapy Drug made from allogeneic stem cells derived from adipose tissue in a rat model of chronic rotator cuff injury.

MATERIAL AND METHODS

The supraspinatus lesion was created in 48 rats for subsequent suturing at 4 weeks. MSCs in suspension were added to 24 animals after suturing, and HypoThermosol-FRS® (HTS) to 24 animals as a control group. Histology (Åström and Rausing scale) and the maximum load, displacement and elastic constant of the supraspinatus tendon were analyzed in both groups 4 months after the repair.

RESULTS

No statistically significant differences were found in the histological score comparing the tendons treated with MSCs with respect to the tendons treated with HTS (P=.811) nor in the results of maximum load (P=.770), displacement (P=.852) or elastic constant (P=.669) of the tendon in both groups.

CONCLUSIONS

The addition of adipose-derived cells in suspension to the repair of a chronic cuff injury does not improve the histology or biomechanics of the sutured tendon.

Liquid Storage of Peripheral Blood Stem Cell Products: Effects of Time and Temperature on Product Quality

Unrelated donor peripheral blood stem cell (PBSC) products often require transport to distant locations, which may take up to 72 hours. Temperature is an important variable that can be controlled during PBSC storage or transport; therefore, we studied the impact of temperature on prolonged storage of clinical-grade, mobilized PBSC products. PBSC products were collected by apheresis from 3 granulocyte colony-stimulating factor-mobilized donors, split into 2 PVC blood bags of equal volume, and stored at room temperature (RT) (18°C to 25 ºC) or 4 °C (2°C to 8 ºC) for 96 hours. Samples were obtained at 24-hour intervals for pH, cell counts, flow cytometry phenotyping and viability (7AAD), and hematopoietic colony-forming units (CFU). Starting PBSC products contained 52, 65, and 38 × 109 total nucleated cells (TNCs), with cell concentrations of 125, 263, and 94.6 × 106 TNCs/mL, respectively. Product pH dropped during storage, with significantly lower values for RT stored products than for 4 ºC stored products, and was greatest in the product with the highest TNC count. The percent recovery of viable CD34+ progenitor cells, CD3+ T cells, CD4+ T helper cells, CD8+ cytotoxic T cells, CD19+ B cells, CD15+ granulocytes, CD14+ monocytes, and CD16+/56+ natural killer (NK) cells all decreased over 96 hours but decreased more dramatically in the RT group. Cell recovery differences were statistically significant at most time points for all cell populations except CD15+ granulocytes. For CD34+ cells stored at 4 °C, mean recovery from prestorage values were 97 ± 3% at 24 hours, 87 ± 4% at 48 hours, 88 ± 10% at 72 hours, and 78 ± 1% at 96 hours, compared to RT product values of 45 ± 11%, 19 ± 19%, 2 ± 2%, and 0 ± 0%, respectively. CFUs were well preserved through 96 hours at 4 ºC but not at RT. During PBSC storage, pH and content of viable CD34+ cells, T cells, B cells, monocytes, NK cells, and CFU all declined. However, at 4 ºC, viable cell recoveries are relatively well preserved, even at 72 hours, whereas RT storage resulted in rapid product deterioration. PBSC products requiring prolonged liquid storage or transport before cryopreservation or infusion should be maintained at 4 ºC.

INSPIRED Symposium Part 4A: Access to CAR T Cell Therapy in Unique Populations with B Cell Acute Lymphoblastic Leukemia

The approval of tisagenlecleucel (tisa-cel) for use in children with B cell acute lymphoblastic leukemia (B-ALL) was based on the phase 2 ELIANA trial, a global registration study. However, the ELIANA trial excluded specific subsets of patients facing unique challenges and did not include a sufficient number of patients to adequately evaluate outcomes in rare subpopulations. Since the commercialization of tisa-cel, data have become available that support therapeutic indications beyond the specific cohorts previously eligible for chimeric antigen receptor (CAR) T cells targeted to CD19 (CD19 CAR-T) therapy on the registration clinical trial. Substantial real-world data and aggregate clinical trial data have addressed gaps in our understanding of response rates, longer-term efficacy, and toxicities associated with CD19 CAR-T in special populations and rare clinical scenarios. These include patients with central nervous system relapsed disease, who were excluded from ELIANA and other early CAR-T trials owing to concerns about risk of neurotoxicity that have not been born out. There is also interest in the use of CD19 CAR-T for very-high-risk patients earlier in the course of therapy, such as patients with persistent minimal residual disease after 2 cycles of upfront chemotherapy and patients with first relapse of B-ALL. However, these indications are not specified on the label for tisa-cel and historically were not included in eligibility criteria for most clinical trials; data addressing these populations are needed. Populations at high risk of relapse, including patients with high-risk cytogenetic lesions, infants with B-ALL, patients with trisomy 21, and young adults with B-ALL, also may benefit from earlier treatment with CD19 CAR-T. It is important to prospectively study patient-reported outcomes given the differential toxicity expected between CD19 CAR-T and the historic standard of care, hematopoietic cell transplantation. Now that CD19 CAR-T therapy is commercially available, studies evaluating potential access disparities created by this very expensive novel therapy are increasingly pressing.

Efficacy and Toxicity of CD19 Chimeric Antigen Receptor T Cell Therapy for Lymphoma in Solid Organ Transplant Recipients: A Systematic Review and Meta-Analysis

The safety and efficacy of chimeric antigen receptor (CAR) T cell therapy in solid organ transplant recipients is poorly understood, given the paucity of available data in this patient population. There is a theoretical risk of compromising transplanted organ function with CAR T cell therapy; conversely, organ transplantation-related immunosuppression can alter the function of CAR T cells. Given the prevalence of post-transplantation lymphoproliferative disease, which often can be difficult to treat with conventional chemoimmunotherapy, understanding the risks and benefits of delivering lymphoma-directed CAR T cell therapy in solid organ transplant recipients is of utmost importance. We sought to determine the efficacy of CAR T cell therapy in solid organ transplant recipients as well as the associated adverse effects, including cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and compromised solid organ transplant function. We conducted a systematic review and meta-analysis of adult recipients of solid organ transplant who received CAR T cell therapy for non-Hodgkin lymphoma. Primary outcomes included efficacy, defined as overall response (OR), complete response (CR), progression-free survival, and overall survival, as well as rates of CRS and ICANS. Secondary outcomes included rates of transplanted organ loss, compromised organ function, and alterations to immunosuppressant regimens. After a systematic literature review and 2-reviewer screening process, we identified 10 studies suitable for descriptive analysis and 4 studies suitable for meta-analysis. Among all patients, 69% (24 of 35) achieved a response to CAR T cell therapy, and 52% (18 of 35) achieved a CR. CRS of any grade occurred in 83% (29 of 35), and CRS grade ≥3 occurred in 9% (3 of 35). Sixty percent of the patients (21 of 35) developed ICANS, and 34% (12 of 35) developed ICANS grade ≥3. The incidence of any grade 5 toxicity among all patients was 11% (4 of 35). Fourteen percent of the patients (5 of 35) experienced loss of the transplanted organ. Immunosuppressant therapy was held in 22 patients but eventually restarted in 68% of them (15 of 22). Among the studies included in the meta-analysis, the pooled OR rate was 70% (95% confidence interval [CI], 29.2% to 100%; I2 = 71%) and the pooled CR rate was 46% (95% CI, 25.4% to 67.8%; I2 = 29%). The rates of any grade CRS and grade ≥3 CRS were 88% (95% CI, 69% to 99%; I2 = 0%) and 5% (95% CI, 0% to 21%; I2 = 0%), respectively. The rates of any grade ICANS and ICANS grade ≥3 were 54% (95% CI, 9% to 96%; I2 = 68%) and 40% (95% CI, 3% to 85%; I2 = 63%), respectively. The efficacy of CAR T cell therapy in solid organ transplant recipients is comparable to that in the general population as reported in prior investigational studies, with an acceptable toxicity profile in terms of CRS, ICANS, and transplanted organ compromise. Further studies are needed to determine long-term effects on organ function, sustained response rates, and best practices peri-CAR T infusion period in this patient population.

Antibody based therapies in Hodgkin lymphoma

Multimodality treatment approaches, with systemic therapies at their core, have made Hodgkin Lymphoma a highly curable cancer. Unmet needs remain. Resistance to therapy manifested by refractory and relapsed disease, and treatment related short- and long-term morbidity are the key challenges. Patient outcomes have improved in the recent past with the advent of novel therapies and are borne out of a better understanding of the disease biology and translational medicine. Antibody based therapies, more broadly immunotherapies, are leading the change in the way we treat this disease. This review looks at the tumor antigen-directed immunotherapies, and immune checkpoint inhibitors that are attempting to overcome the unmet challenges.

[Translated article] Efficacy of transplantation of lipoaspired mesenchymal stem cells in the treatment of chronic rotator cuff tears. Experimental model in rats

BACKGROUND AND AIM

Rotator cuff tears emerge in approximately 30% of the population over 60 years of age. Arthroscopic surgical treatment of these lesions is the treatment of choice, however, despite the improved repair techniques, the rate of re-tears ranges between 11 and 94%. Therefore, researchers seek to improve the biological healing process through the use of different alternatives such as mesenchymal stem cells (MSCs). Our objective is to evaluate the efficacy of a cellular therapy drug made from allogeneic stem cells derived from adipose tissue in a rat model of chronic rotator cuff injury.

MATERIAL AND METHODS

The supraspinatus lesion was created in 48 rats for subsequent suturing at 4 weeks. MSCs in suspension were added to 24 animals after suturing, and HypoThermosol-FRS® (HTS) to 24 animals as a control group. Histology (Åström and Rausing scale) and the maximum load, displacement and elastic constant of the supraspinatus tendon were analysed in both groups 4 months after the repair.

RESULTS

No statistically significant differences were found in the histological score comparing the tendons treated with MSCs with respect to the tendons treated with HTS (P=0.811) nor in the results of maximum load (P=0.770), displacement (P=0.852) or elastic constant (P=0.669) of the tendon in both groups.

CONCLUSIONS

The addition of adipose-derived cells in suspension to the repair of a chronic cuff injury does not improve the histology or biomechanics of the sutured tendon.

Chimeric Antigen Receptor T Cell Therapy for Myeloma: Where Are We Now and What Is Needed to Move Chimeric Antigen Receptor T Cells Forward to Earlier Lines of Therapy? Expert Panel Opinion from the American Society for Transplantation and Cellular Therapy

Since 2021, 2 B cell maturation antigen (BCMA)-directed chimeric antigen receptor T cell (CAR-T) therapies-idecabtagene vicleucel (ide-cel), and ciltacabtagene autoleucel (cilta-cel)-have been approved by the US Food and Drug Administration (FDA) for treating relapsed or refractory multiple myeloma (RRMM) after 4 or more prior lines of therapy, including an immunomodulatory drug, a proteasome inhibitor, and an anti-CD38 antibody. The 2 products have shown unprecedented activity in RRMM, but relapses remain common, and access to and safety of CAR-T therapy in patients with rapidly progressing advanced disease are not ideal. Sequencing CAR-T therapy with other options, including the 2 recently approved BCMA-directed T cell-engaging bispecific antibodies teclistamab and elranatamab, has become increasingly challenging owing to data showing inferior outcomes from CAR-T therapy after prior BCMA-directed therapy. This has led to the consideration of CAR-T therapy earlier in the course of disease for myeloma, when T cells are potentially healthier and the myeloma is less aggressive. To address the question of earlier use of CAR-T therapy, several trials are either ongoing or planned, and results have recently been reported for 2 randomized trials of CAR-T therapy showing improved progression-free survival compared to standard of care therapy in second-line (CARTITUDE-4) or third-line therapy (KarMMA-3). With the anticipation of the FDA possibly expanding approval of CAR-T to earlier lines of myeloma therapy, the American Society for Transplantation and Cellular Therapy convened a group of experts to provide a comprehensive review of the studies that led to the approval of CAR-T therapy in late-line therapy for myeloma, discuss the recently reported and ongoing studies designed to move CAR-T therapy to earlier lines of therapy, and share insights and considerations for sequencing therapy and optimization of patient selection for BCMA-directed therapies in current practice.

Identification of a fundamental cryoinjury mechanism in MSCs and its mitigation through cell-cycle synchronization prior to freezing

Clinical development of cellular therapies, including mesenchymal stem/stromal cell (MSC) treatments, has been hindered by ineffective cryopreservation methods that result in substantial loss of post-thaw cell viability and function. Proposed solutions to generate high potency MSC for clinical testing include priming cells with potent cytokines such as interferon gamma (IFNγ) prior to cryopreservation, which has been shown to enhance post-thaw function, or briefly culturing to allow recovery from cryopreservation injury prior to administering to patients. However, both solutions have disadvantages: cryorecovery increases the complexity of manufacturing and distribution logistics, while the pleiotropic effects of IFNγ may have uncharacterized and unintended consequences on MSC function. To determine specific cellular functions impacted by cryoinjury, we first evaluated cell cycle status. It was discovered that S phase MSC are exquisitely sensitive to cryoinjury, demonstrating heightened levels of delayed apoptosis post-thaw and reduced immunomodulatory function. Blocking cell cycle progression at G0/G1 by growth factor deprivation (commonly known as serum starvation) greatly reduced post-thaw dysfunction of MSC by preventing apoptosis induced by double-stranded breaks in labile replicating DNA that form during the cryopreservation and thawing processes. Viability, clonal growth and T cell suppression function were preserved at pre-cryopreservation levels and were no different than cells prior to freezing or frozen after priming with IFNγ. Thus, we have developed a robust and effective strategy to enhance post-thaw recovery of therapeutic MSC.

The Future of Chimeric Antigen Receptor T Cell Therapy

Over the last 10 years CAR T cell therapies have been shown to be transformative for B- and plasma-cell malignancies, however the field is only beginning to realize the potential benefit to patients of such therapies. Over the next 10 years it is expected that advances will be made in durable response rates for patients with B/plasma cell malignancies; expansion to T-cell, myeloid, and solid malignancies; and in delivery and manufacturing to transform the field.

Proceedings of the 2023 Second Annual ASTCT-NMDP ACCESS Initiative Workshop

Here the proceedings from the Second Annual American Society for Transplantation and Cellular Therapy (ASTCT) and National Marrow Donor Program (NMDP) ACCESS Initiative are reviewed to inform the hematopoietic cell transplantation (HCT) and cellular therapy (CT) ecosystem about progress and direction of the collaborative. Highlights from the meeting, including updates on the progress of projects from the Awareness, Poverty, and Racial Inequity Committees, are presented. The ACCESS Initiative continues to evolve and will remain dependent on the HCT/CT ecosystem's continued dedication to reduce barriers and improve outcome disparities for all patients in need of HCT/CT.

Phase I non-randomized clinical trial of allogeneic natural killer cells infusion in acute myeloid leukemia patients

INTRODUCTION

A new type of immune cell transplantation called allogeneic NK cell infusion is proposed as a potential universal off-the-shelf cell product for adoptive immune cell therapy in hematologic malignancies.

DESIGN

A multicentral phase I non-randomized clinical trial was conducted to assess the safety, feasibility, and potential efficacy of adoptively infused NK cells in patients with refractory/relapsed AML. We evaluated the feasibility of the trial by considering cell production, patient selection, and treatment protocol.

METHOD

Allogeneic NK cells were produced from random healthy unrelated donors; 10 patients were selected according to the inclusion criteria and were included in two groups in case of NK cell dose escalation. Two cell infusions were given, spaced 7 days apart, following a lymphodepletion conditioning regimen of fludarabin-endoxan administered 7 days before the first infusion. The intervention safety was scored using Common Terminology Criteria for Adverse Events (CTCAE) based on variations in vital signs due to cell infusion. NK cell chimerism, tumor burden, and duration of relapse were considered to be components of efficacy. The pilot feasibility evaluation was checked using the CONSORT platform.

RESULTS

The NK cell infusion procedure was well tolerated, and no grade 2-5 toxicities related (possible or probable) to PB-NK cell infusion were observed. Four patients developed grade 1 transient chills, headaches, vomiting, and bone pain following each PB-NK cell infusion that were not required hospitalization. One of these patients (p01) died because of severe acute respiratory syndrome. Of 9 evaluable patients, 6 (66.6%) showed stable disease (SD) and 3 (33.3%) presented progressive disease (PD). Of 6 SD patients, 2 (p08 and p09) remained alive in SD and 3 patients (p04, p05 and p07) converted to PD at 9 months after infusion of NK cells, and 1 (p03) was not evaluable due to follow-up loss. No patient achieved complete remission.

CONCLUSION

The study demonstrated the feasibility and safety of adoptive transfer of random healthy unrelated donor PB-NK cells in refractory/relapsed AML patients and supports continued study in phase II clinical trials in relapsed/refractory AML patients.

SOHO State of the Art Updates and Next Questions | Treatment of Richter's Transformation

Richter's transformation (RT) is a rare condition, represented by the development of an aggressive lymphoma arising from underlying chronic lymphocytic leukemia/small lymphocytic lymphoma. The management of RT remains challenging, necessitating combined therapeutic strategies to achieve favorable outcomes. Traditional treatment options for RT have involved intensive chemotherapy regimens, often with limited success due to the high-risk nature of the disease. However, recent advances in the understanding of RT pathogenesis have led to the emergence of novel targeted therapies that show promising results. Noncovalent Bruton tyrosine kinase inhibitors, T-cell-engaging bispecific antibodies, chimeric antigen receptor T-cells, and conjugated monoclonal antibodies may hold promise for improved outcomes in RT, especially when combined in a multitargeted fashion. Further prospective randomized trials and collaborative efforts are warranted to optimize treatment algorithm and ultimately improve patient outcomes in this dismal condition. This review provides a comprehensive overview of the current treatment options for RT.

Human Multi-Chimeric Cell (HMCC) Therapy as a Novel Approach for Tolerance Induction in Transplantation

Cellular therapies are regarded as the most promising approach for inducing transplant tolerance without life-long immunosuppression in solid organ and vascularized composite allotransplantation (VCA). Currently, no therapies are achieving this goal. This study introduces a novel Human Multi-Chimeric Cell (HMCC) line created by fusion of umbilical cord blood (UCB) cells, from three unrelated donors as an alternative therapeutic approach to bone marrow transplantation and tolerance induction in solid organ and VCA transplants. We performed eighteen ex vivo polyethylene glycol mediated fusions of human UCB cells from three unrelated donors to create HMCC. Mononuclear cells labeled with PKH26, PKH67, and eFluor™ 670 fluorescent dyes were fused and sorted creating a new population of triple-labeled (PKH26/PKH67/eFluor™ 670) HMCC. The creation of HMCC from three unrelated human UCB donors was confirmed by flow cytometry and confocal microscopy. Genotyping analyses determined the tri-chimeric state of HMCC by presence of parent alleles and selected loci specific for each of three UCB donors. Phenotype characterization confirmed hematopoietic markers distribution, comparable to UCB donors. HMCC maintained viability and displayed a low apoptosis level. The COMET assay revealed absence of genotoxicity, confirming fusion safety. Colony forming units assay showed clonogenic properties of HMCC. This study confirmed the feasibility of HMCC creation from three unrelated human UCB donors and characterized tri-chimeric state, hematopoietic phenotype, viability, safety, and clonogenic properties of HMCC. The created HMCC line, representing genotype characteristics of three unrelated human UCB donors, introduces a novel therapeutic approach for bone marrow, solid organ, and VCA transplants.

Autologous mesenchymal stromal cells embedded with Tissucol Duo® for prevention of air leak after anatomical lung resection: results of a prospective phase I/II clinical trial with long-term follow-up

BACKGROUND

Prolonged air leak (PAL) is the most frequent complication after pulmonary resection. Several measures have been described to prevent the occurrence of PAL in high-risk patients, however, the potential role of mesenchymal stem cells (MSCs) applied in the parenchymal suture line to prevent postoperative air leak in this setting has not been fully addressed.

OBJECTIVE

To analyse the feasibility, safety and potential clinical efficacy of the implantation of autologous MSCs embedded in Tissucol Duo® as a prophylactic alternative to prevent postoperative prolonged air leak after pulmonary resection in high-risk patients.

STUDY DESIGN

Phase I/II single-arm prospective clinical trial.

METHODS

Six patients with high risk of PAL undergoing elective pulmonary resection were included. Autologous bone marrow-derived MSCs were expanded at our Good Manufacturing Practice (GMP) Facility and implanted (embedded in a Tissucol Duo® carrier) in the parenchymal suture line during pulmonary resection surgery. Patients were monitored in the early postoperative period and evaluated for possible complications or adverse reactions. In addition, all patients were followed-up to 5 years for clinical outcomes.

RESULTS

The median age of patients included was 66 years (range: 55-70 years), and male/female ratio was 5/1. Autologous MSCs were expanded in five cases, in one case MSCs expansion was insufficient. There were no adverse effects related to cell implantation. Regarding efficacy, median air leak duration was 0 days (range: 0-2 days). The incidence of PAL was nil. Radiologically, only one patient presented pneumothorax in the chest X-ray at discharge. No adverse effects related to the procedure were recorded during the follow-up.

CONCLUSIONS

The use of autologous MSCs for prevention of PAL in patients with high risk of PAL is feasible, safe and potentially effective.

TRIAL REGISTRATION NO

EudraCT: 2013-000535-27.

CLINICALTRIALS

gov idenfier: NCT02045745.

αβ-T cell receptor transduction gives superior mitochondrial function to γδ-T cells with promising persistence

Adoptive cell therapy using allogeneic γδ-T cells is a promising option for off-the-shelf T cell products with a low risk of graft-versus-host disease (GVHD). Long-term persistence may boost the clinical development of γδ-T cell products. In this study, we found that genetically modified Vγ9+Vδ2+ T cells expressing a tumor antigen-specific αβ-TCR and CD8 coreceptor (GMC) showed target-specific killing and excellent persistence. To determine the mechanisms underlying these promising effects, we investigated metabolic characteristics. Cytokine secretion by γδ-TCR-stimulated nongene-modified γδ-T cells (NGMCs) and αβ-TCR-stimulated GMCs was equally suppressed by a glycolysis inhibitor, although the cytokine secretion of αβ-TCR-stimulated GMCs was more strongly inhibited by ATP synthase inhibitors than that of γδ-TCR-stimulated NGMCs. Metabolomic and transcriptomic analyses, flow cytometry analysis using mitochondria-labeling dyes and extracellular flux analysis consistently suggest that αβ-TCR-transduced γδ-T cells acquire superior mitochondrial function. In conclusion, αβ-TCR-transduced γδ-T cells acquire superior mitochondrial function with promising persistence.

Cellular Therapy in Chronic Lymphocytic Leukemia: Have We Advanced in the Last Decade?

BACKGROUND

Chronic lymphocytic leukemia (CLL) is a heterogeneous B-cell malignancy, affecting mainly older adults. Despite the recent introduction of multiple targeted agents, CLL remains an incurable disease. Cellular therapy is a promptly evolving area that has developed over the last decades from such standard of care as hematopoietic cell transplantation (HCT) to the novel treatment modalities employing genetically engineered immune cells.

SUMMARY

Tailoring the proper treatment for each patient is warranted and should take into account the disease biology, patient characteristics, and the available treatment modalities. Nowadays, the most broadly applied cellular therapies for CLL management are HCT and chimeric antigen receptor-T (CAR-T) cells. However, CAR-T cell therapy is currently not yet approved in CLL, and the appropriate sequencing for the administration of these agents remains to be clarified.

KEY MESSAGES

The current review will discuss various available cellular treatment options, their advances and limitations, as well as the optimal timing for the employment of such therapies in CLL patients.

Predicting infections in patients with haematological malignancies treated with chimeric antigen receptor T-cell therapies: A systematic scoping review and narrative synthesis

BACKGROUND

Chimeric antigen receptor T cells (CAR-T cells) are increasingly used to treat haematological malignancies. Strategies for preventing infections in CAR-T-treated patients rely on expert opinions and consensus guidelines.

OBJECTIVES

This scoping review aimed to identify risk factors for infections in CAR-T-treated patients with haematological malignancies.

DATA SOURCES

A literature search utilized MEDLINE, EMBASE and Cochrane to identify relevant studies from conception until 30 September 2022.

STUDY ELIGIBILITY CRITERIA

Trials and observational studies were eligible.

PARTICIPANTS

Studies required ≥10 patients treated for haematological malignancy to report infection events (as defined by the study), and either (a) a descriptive, univariate or multivariate analysis of the relationship between infections event and a risk factors for infections, or (b) diagnostic performance of a biochemical/immunological marker in CAR-T-treated patients with infection.

METHODS

A scoping review was conducted in accordance with PRISMA guidelines.

DATA SOURCES

A literature search utilised MEDLINE, EMBASE and Cochrane to identify relevant studies from conception until September 30, 2022. Eligibility/Participants/Intervention: Trials and observational studies were eligible. Studies required ≥ 10 patients treated for haematological malignancy, to report infection events (as defined by the study), and either A) a descriptive, univariate or multivariate analysis of the relationship between infections event and a risk-factors for infections, or B) diagnostic performance of a biochemical/immunological marker in CAR-T treated patients with infection.

ASSESSMENT OF RISK OF BIAS

Bias assessment was undertaken according to Joanna Brigg's Institute criteria for observational studies.

METHODS OF DATA SYNTHESIS

Data were synthesized descriptively because of the heterogeneity of reporting.

RESULTS

A total of 1522 patients across 15 studies were identified. All-cause infections across haematological malignancies were associated with lines of prior therapy, steroid administration, immune-effector cell-associated neurotoxicity and treatment-emergent neutropenia. Procalcitonin, C-reactive protein and cytokine profiles did not reliably predict infections. Predictors of viral, bacterial and fungal infections were poorly canvassed.

DISCUSSION

Meta-analysis of the current literature is not possible because of significant heterogeneity in definitions of infections and risk factors, and small, underpowered cohort studies. Radical revision of how we approach reporting infections for novel therapies is required to promptly identify infection signals and associated risks in patients receiving novel therapies. Prior therapies, neutropenia, steroid administration and immune-effector cell-associated neurotoxicity remain the most associated with infections in CAR-T-treated patients.

Multiple Dimensions of using Mesenchymal Stem Cells for Treating Liver Diseases: From Bench to Beside

Liver diseases impose a huge burden worldwide. Although hepatocyte transplantation has long been considered as a potential strategy for treating liver diseases, its clinical implementation has created some obvious limitations. As an alternative strategy, cell therapy, particularly mesenchymal stem cell (MSC) transplantation, is widely used in treating different liver diseases, including acute liver disease, acute-on-chronic liver failure, hepatitis B/C virus, autoimmune hepatitis, nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, alcoholic liver disease, liver fibrosis, liver cirrhosis, and hepatocellular carcinoma. Here, we summarize the status of MSC transplantation in treating liver diseases, focusing on the therapeutic mechanisms, including differentiation into hepatocyte-like cells, immunomodulating function with a variety of immune cells, paracrine effects via the secretion of various cytokines and extracellular vesicles, and facilitation of homing and engraftment. Some improved perspectives and current challenges are also addressed. In summary, MSCs have great potential in the treatment of liver diseases based on their multi-faceted characteristics, and more accurate mechanisms and novel therapeutic strategies stemming from MSCs will facilitate clinical practice.

Targeted cellular therapy for treatment of relapsed or refractory leukemia

While the mainstay of treatment for high-risk or relapsed, refractory leukemia has historically revolved around allogeneic hematopoietic stem cell transplant (allo-HSCT), targeted immunotherapies have emerged as a promising therapeutic option, especially given the poor prognosis of patients who relapse after allo-HSCT. Novel cellular immunotherapies that harness the cytotoxic abilities of the immune system in a targeted manner (often called "adoptive" cell therapy), have changed the way we treat r/r hematologic malignancies and continue to change the treatment landscape given the rapid evolution of these powerful, yet sophisticated precision therapies that often offer a less toxic alternative to conventional salvage therapies. Importantly, adoptive cell therapy can be allo-HSCT-enabling or a therapeutic option for patients in whom transplantation has failed or is contraindicated. A solid understanding of the core concepts of adoptive cell therapy is necessary for stem cell transplant physicians, nurses and ancillary staff given its proximity to the transplant field as well as its inherent complexities that require specific expertise in compliant manufacturing, clinical application, and risk mitigation. Here we will review use of targeted cellular therapy for the treatment of r/r leukemia, focusing on chimeric antigen receptor T-cells (CAR T-cells) given the remarkable sustained clinical responses leading to commercial approval for several hematologic indications including leukemia, with brief discussion of other promising investigational cellular immunotherapies and special considerations for sustainability and scalability.

ASTCT Clinical Practice Recommendations for Transplantation and Cellular Therapies in Diffuse Large B Cell Lymphoma

Autologous hematopoietic cell transplantation (auto-HCT) has long been the standard approach for patients with relapsed/refractory (R/R) chemosensitive diffuse large B cell lymphoma (DLBCL). However, the advent of chimeric antigen receptor (CAR) T cell therapy has caused a paradigm shift in the management of R/R DLBCL patients, especially with the recent approval of CD19-directed CAR-T therapy in the second-line setting in high-risk groups (primary refractory and early relapse [≤12 months]). Consensus on the contemporary role, optimal timing, and sequencing of HCT and cellular therapies in DLBCL is lacking; therefore, the American Society of Transplantation and Cellular Therapy (ASTCT) Committee on Practice Guidelines undertook this project to formulate consensus recommendations to address this unmet need. The RAND-modified Delphi method was used to generate 20 consensus statements with a few key statements as follows: (1) in the first-line setting, there is no role for auto-HCT consolidation for patients achieving complete remission (CR) following R-CHOP (rituximab, cyclophosphamide, adriamycin, vincristine, and prednisone) or similar therapy in non-double-hit/triple-hit cases (DHL/THL) and in DHL/THL cases receiving intensive induction therapies, but auto-HCT may be considered in eligible patients receiving R-CHOP or similar therapies in DHL/THL cases; (2) auto-HCT consolidation with thiotepa-based conditioning is standard of care for eligible patients with primary central nervous system lymphoma achieving CR with first-line therapy; and (3) in the primary refractory and early relapse setting, the preferred option is CAR-T therapy, whereas in late relapse (>12 months), consolidation with auto-HCT is recommended for patients achieving chemosensitivity to salvage therapy (complete or partial response), and CAR-T therapy is recommended for those not achieving remission. These clinical practice recommendations will serve as a tool to guide clinicians managing patients with newly diagnosed and R/R DLBCL.

The other side of the coin: mesenchymal stromal cell immortalization beyond evasion of senescence

Mesenchymal stromal cells (MSC) are promising options to cellular therapy to several clinical disorders, mainly because of its ability to immunomodulate and differentiate into different cell types. Even though MSC can be isolated from different sources, a major challenge to understanding the biological effects is that the primary cells undergo replicative senescence after a limited number of cell divisions in culture, requiring time-consuming and technically challenging approaches to get a sufficient cell number for clinical applications. Therefore, a new isolation, characterization, and expansion is necessary every time, which increases the variability and is time-consuming. Immortalization is a strategy that can overcome these challenges. Therefore, here, we review the different methodologies available to cellular immortalization, and discuss the literature regarding MSC immortalization and the broader biological consequences that extend beyond the mere increase in proliferation potential.

Eradication of CD48-positive tumors by selectively enhanced YTS cells harnessing the lncRNA NeST

Natural killer (NK) cells are currently used in clinical trials to treat tumors. However, such therapies still suffer from problems such as donor variability, reproducibility, and more, which prevent a wider use of NK cells therapeutics. Here we show a potential immunotherapy combining NK cell-mediated tumor eradiation and long non-coding (lnc) RNAs. We overexpressed the interferon (IFN) γ secretion-enhancing lncRNA nettoie Salmonella pas Theiler's (NeST) in the NK cell-like cell line YTS. YTS cells express the co-stimulatory receptor 2B4 whose main ligand is CD48. On YTS cells, 2B4 functions by direct activation. We showed that NeST overexpression in YTS cells resulted in increased IFNγ release upon interaction with CD48 (selectively enhanced (se)YTS cells). Following irradiation, the seYTS cells lost proliferation capacity but were still able to maintain their killing and IFNγ secretion capacities. Finally, we demonstrated that irradiated seYTS inhibit tumor growth in vivo. Thus, we propose seYTS cells as off-the-shelve therapy for CD48-expressing tumors.

How do we improve the translation of new evidence into the practice of hematopoietic cell transplantation and cellular therapy?

The field of hematopoietic cell transplantation and cell therapy (HCT/CT) is advancing rapidly to bring an ever-expanding collection of potentially curative therapies to patients with malignant and non-malignant diseases. The impact of these therapies depends on our ability to implement them as new evidence becomes available to advance the quality of care. There is often a long delay between evidence development and adoption of therapies based on that evidence into clinical practice. In this review, we describe the potential factors based on an implementation framework that could act as facilitators or barriers to adoption of therapies in the context of HCT/CT. We highlight two examples, the first to showcase the efforts to improve the efficiency of adoption of new findings and accelerate improvement in care of HCT/CT patients and the second to discuss the challenges in real world implementation of chimeric antigen receptor T cell therapy. We conclude by reviewing strategies to improve translation of evidence and ways to measure their success.

An update on stem cell and stem cell-derived extracellular vesicle-based therapy in the management of Alzheimer's disease

Globally, neurological diseases pose a major burden to healthcare professionals in terms of the management and prevention of the disorder. Among neurological diseases, Alzheimer's disease (AD) accounts for 50%-70% of dementia and is the fifth leading cause of mortality worldwide. AD is a progressive, degenerative neurological disease, with the loss of neurons and synapses in the cerebral cortex and subcortical regions. The management of AD remains a debate among physicians as no standard and specific "disease-modifying" modality is available. The concept of 'Regenerative Medicine' is aimed at regenerating the degenerated neural tissues to reverse the pathology in AD. Genetically modified engineered stem cells modify the course of AD after transplantation into the brain. Extracellular vesicles (EVs) are an emerging new approach in cell communication that involves the transfer of cellular materials from parental cells to recipient cells, resulting in changes at the molecular and signaling levels in the recipient cells. EVs are a type of vesicle that can be transported between cells. Many have proposed that EVs produced from mesenchymal stem cells (MSCs) may have therapeutic promise in the treatment of AD. The biology of AD, as well as the potential applications of stem cells and their derived EVs-based therapy, were explored in this paper.

Reconstitution and post-thaw storage of cryopreserved human mesenchymal stromal cells: Pitfalls and optimizations for clinically compatible formulants

Introduction

The regenerative and immunomodulatory properties of multipotent mesenchymal stromal cells (MSCs) make them an intriguing asset for therapeutic applications. An off-the-shelf approach, using pre-expanded cryopreserved allogenic MSCs, bypasses many practical difficulties of cellular therapy. Reconstitution of a MSC product away from cytotoxic cryoprotectants towards a preferred administration solution might be favorable for several indications. Variations in MSC handling accompanied by a non-standardized use of reconstitution solutions complicate a general clinical standardization of MSC cellular therapies. In this study, we aimed to identify a simple and clinically compatible approach for thawing, reconstitution, and post-thaw storage of cryopreserved MSCs.

Methods

Human adipose tissue-derived MSCs were expanded in human platelet lysate (hPL) supplemented culture medium and cryopreserved using a dimethyl sulfoxide (DMSO)-based cryoprotectant. Isotonic solutions (saline, Ringer's acetate and phosphate buffered saline (PBS)) with or without 2% human serum albumin (HSA) were used as thawing, reconstitution, and storage solutions. MSCs were reconstituted to 5 × 10⁶ MSCs/mL for evaluating MSC stability. Total MSC numbers and viability were determined using 7-aminoactinomycin D (7-AAD) and flow cytometry.

Results

For thawing cryopreserved MSCs the presence of protein was proven to be essential. Up to 50% of MSCs were lost when protein-free thawing solutions were used. Reconstitution and post-thaw storage of MSCs in culture medium and widely used PBS demonstrated poor MSC stability (>40% cell loss) and viability (<80%) after 1 h of storage at room temperature. Reconstitution in simple isotonic saline appeared to be a good alternative for post-thaw storage, ensuring >90% viability with no observed cell loss for at least 4 h. Reconstitution of MSCs to low concentrations was identified as critical. Diluting MSCs to <10⁵/mL in protein-free vehicles resulted in instant cell loss (>40% cell loss) and lower viability (<80%). Addition of clinical grade HSA could prevent cell loss during thawing and dilution.

Conclusion

This study identified a clinically compatible method for MSC thawing and reconstitution that ensures high MSC yield, viability, and stability. The strength of the method lies within the simplicity of implementation which offers an accessible way to streamline MSC therapies across different laboratories and clinical trials, improving standardization in this field.

Immune Reconstitution Profiling Suggests Antiviral Protection After Transplantation with Omidubicel: a Phase 3 Substudy

BACKGROUND

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative treatment for hematological malignancies and non-malignant disorders. Rapid immune reconstitution (IR) following allogeneic HCT has been shown to be associated with improved clinical outcomes and lower infection rates. A global phase 3 trial (NCT02730299) of omidubicel, an advanced cell therapy manufactured from an appropriately human leukocyte antigen-matched single umbilical cord blood (UCB) unit, showed faster hematopoietic recovery, reduced rates of infection, and shorter hospitalizations in patients randomized to omidubicel compared with those randomized to standard UCB.

OBJECTIVE

This optional, prospective substudy of the phase 3 trial characterized the IR kinetics following HCT with omidubicel compared with UCB in a systematic and detailed manner.

STUDY DESIGN

In this substudy, 37 patients from 14 global sites were included (omidubicel: n=17, UCB: n=20). Peripheral blood samples were collected over 10 predefined time points from 7 to 365 days post-HCT. Flow cytometry immunophenotyping, T cell receptor excision circle quantification, and T cell receptor sequencing were employed to evaluate the longitudinal IR kinetics post-transplant and their association with clinical outcomes.

RESULTS

Patient characteristics in the two comparator cohorts were overall statistically similar, except for age and total body irradiation (TBI) based conditioning regimens. The median age (range) for patients who received omidubicel or UCB was 30 (13-62) years and 43 (19-55) years, respectively. The percentages of patients receiving TBI based conditioning regimens were 47% and 70% for omidubicel and UCB recipients, respectively. Graft characteristics differed in their cellular composition. Omidubicel recipients received a 33-fold higher median dose of CD34+ stem cells, while receiving one third of the median CD3+ lymphocyte dose infused to UCB transplanted patients. Compared with UCB, omidubicel recipients exhibited faster IR of all measured lymphoid and myelomonocytic subpopulations, predominantly in the first 14 days post-transplant. This effect involved circulating natural killer (NK) cells, helper T cells, monocytes, and dendritic cells, with superior long-term B cell recovery from Day 28. One-week post-HCT, omidubicel recipients exhibited 4.1 and 7.7 -fold increases in the median helper T and NK cell counts respectively, compared to their UCB transplanted counterparts. By three weeks post-HCT, omidubicel transplanted patients were 3-fold more likely to achieve clinically relevant helper T and NK cell counts of 100 cells/ µL or above. Similar to UCB, omidubicel yielded a balanced cellular subpopulation composition and diverse T cell receptor repertoire in the short to long term. Omidubicel's CD34+ cell content correlated with faster IR by Day 7 post-HCT, which in turn coincided with earlier hematopoietic recovery. Lastly, early NK and helper T cell reconstitution correlated with a decreased rate of post-HCT viral infections, suggesting a plausible explanation for this phenomenon among omidubicel recipients in the phase 3 study.

CONCLUSIONS

Our findings suggest that omidubicel efficiently promotes IR across multiple immune cells, including CD4+ T cells, B cells, NK cells, and dendritic cell subtypes as early as 7 days post-transplant, potentially endowing recipients of omidubicel with early protective immunity.

Therapeutic potential of MSCs and MSC-derived extracellular vesicles in immune thrombocytopenia

Immune thrombocytopenia (ITP) is an acquired autoimmune disease involving a variety of immune cells and factors. Despite being a benign disease, it is still considered incurable due to its complex pathogenesis. Mesenchymal stem cells (MSCs), with low immunogenicity, pluripotent differentiation, and immunomodulatory ability, are widely used in a variety of autoimmune diseases. In recent years, impaired bone marrow mesenchymal stem cells (BMMSCs) were found to play an important role in the pathogenesis of ITP; and the therapeutic role of MSCs in ITP has also been supported by increasing evidence with encouraging efficacy. MSCs hold promise as a new approach to treat or even cure refractory ITP. Extracellular vesicles (EVs), as novel carriers in the "paracrine" mechanism of MSCs, are the focus of MSCs. Encouragingly, several studies suggested that EVs may perform similar functions as MSCs to treat ITP. This review summarized the role of MSCs in the pathophysiology and treatment of ITP.

Phase 1 study to determine the safety and dosing of autologous PBMCs modified to present HPV16 antigens (SQZ-PBMC-HPV) in HLA-A*02+ patients with HPV16+ solid tumors

We conducted a dose escalation Phase 1 study of autologous PBMCs loaded by microfluidic squeezing (Cell Squeeze® technology) with HPV16 E6 and E7 antigens (SQZ-PBMC-HPV), in HLA-A*02+ patients with advanced/metastatic HPV16+ cancers. Preclinical studies in murine models had shown such cells resulted in stimulation and proliferation of antigen specific CD8+ cells, and demonstrated antitumor activity. Administration of SQZ-PBMC-HPV was every 3 weeks. Enrollment followed a modified 3+3 design with primary objectives to define safety, tolerability, and the recommended Phase 2 dose. Secondary and exploratory objectives were antitumor activity, manufacturing feasibility, and pharmacodynamic evaluation of immune responses. Eighteen patients were enrolled at doses ranging from 0.5 × 106 to 5.0 × 106 live cells/kg. Manufacture proved feasible and required < 24 h within the overall vein-to-vein time of 1 - 2 weeks; at the highest dose, a median of 4 doses were administered. No DLTs were observed. Most related TEAEs were Grade 1 - 2, and one Grade 2 cytokine release syndrome SAE was reported. Tumor biopsies in three patients showed 2 to 8-fold increases in CD8+ tissue infiltrating lymphocytes, including a case that exhibited increased MHC-I+ and PD-L1+ cell densities and reduced numbers of HPV+ cells. Clinical benefit was documented for the latter case. SQZ-PBMC-HPV was well tolerated; 5.0 × 106 live cells/kg with double priming was chosen as the recommended Phase 2 dose. Multiple participants exhibited pharmacodynamic changes consistent with immune responses supporting the proposed mechanism of action for SQZ-PBMC-HPV, including patients previously refractory to checkpoint inhibitors.

Patient-reported cognitive function among hematopoietic stem cell transplant and cellular therapy patients: a scoping review

PURPOSE

Cognitive dysfunction is a known complication following cellular therapies (CT), which can be assessed through performance based and patient-reported measures. We performed a systematic scoping review to assess self-reported cognitive function measures used among adult CT patients and describe long-term results, including associations with clinical outcomes.

METHODS

Library databases were searched from inception to February 2020 according to PRISMA guidelines. Additional studies were identified through reference lists and trial protocols. Two members of the research team screened titles and abstracts and resolved discrepancies. Articles that met eligibility criteria continued to full-text review, with 25% double screening. Articles were removed if they (1) were not original research, peer-reviewed articles; (2) were the wrong disease, age, or treatment-specific patient population; (3) did not use patient-reported outcomes; (4) did not separately report cognitive function outcomes.

RESULTS

Of the1952 articles, 56 were included. Twenty-one patient-reported measures of cognitive function were used; most frequently the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC-QLQ-C30), which includes a two-item cognitive function subscale (57%; n = 32). Thirteen studies collected performance-based and self-reported measures and of those (n = 6) who assessed associations found moderate correlations (range r = .13-.58). Longitudinal patterns showed declines in cognitive function soon after treatment (< 1 month) returning to baseline at 1 year. Cognitive function was often associated with other quality of life measures, chiefly depression (n = 5).

CONCLUSIONS

EORTC-QLQ-C30 is the most commonly used to measure, though there remain numerous measures used, including several measures with little previous validation and investigator developed items.

CTLs, NK cells and NK-derived EVs against breast cancer

Patients with advanced stage breast cancer need novel therapies. New potential treatments have been developed, such as adoptive cellular therapies and alternative cell-free immunotherapies. The goal of this study was to assess the cytotoxicity of three of the patient-derived immune components, CTLs, NK cells and NK-derived EVs, and evaluate the potential for the development of novel therapy against breast cancer. CTLs were activated against MUC-1 antigen. The in vitro cytotoxic activity of three components was assessed with flow cytometry and in vivo study revealed the efficacy of adoptive cell therapy. Overall, CTLs exhibited the highest cytotoxicity against spheroids of MCF7 breast adenocarcinoma, reaching in all cases higher than double the percentage of NK cells' cytotoxicity. NK-derived EVs exhibited the lowest effect against MCF7 spheroids comparing to the two cell populations. MUC-1 specific CTLs were evaluated with adoptive cell therapy mice study and appeared to be well tolerable and moderately efficacious. More studies need to be performed with CTLs to evaluate safety and efficacy in order to assess their clinical potential, while NK cells and NK-derived EVs are promising candidates that require more experiments to enhance their cytotoxicity.

CAR T-Cells for the Treatment of Refractory or Relapsed Large B-Cell Lymphoma: A Single-Center Retrospective Canadian Study

BACKGROUND

Chimeric antigen receptor (CAR) T-cells are an important new third-line treatment option for large B-cell lymphoma (LBCL). The objective response rates in pivotal early phase clinical trials with CAR T-cells were very promising. The objective of this study was to describe the efficacy results obtained with CAR T-cells infusions in our institution and to compare the toxicities of our cohort with those of pivotal trials and studies conducted in a real-life setting.

PATIENTS AND METHODS

Efficacy and safety data were retrospectively collected from 25 patients with LBCL treated with CAR T-cells therapy at CHU de Québec-Université Laval. A literature search was then performed to identify other efficacy or safety data from a real-life setting.

RESULTS

At 3 months post infusion, the objective response rate (ORR) in our population with tisagenlecleucel and axicabtagene-ciloleucel were 20% and 47%, respectively. Bulky disease was the only negative predictor of poor response at 3 months (0% vs. 53%, P = .03). Bulky disease was associated with a median PFS of 2 months compared to 5 months for non-bulky disease (P = .0009). Grade ≥ 3 hematological toxicities were greater in patients treated with axi-cel (60% vs. 20%, P = .048), without bone marrow involvement (55% vs. 0%, P =.046), without stage IV disease (72% vs. 21%, P =.02), with refractory disease (67% vs. 10%, P =.01) or having been affected by cytokine release syndrome (58% vs. 0%, P =.02).

CONCLUSION

The poor response rate at 3 months after infusion in our cohort was influenced mainly by bulky disease. Further studies are needed to better characterize the loss of efficacy of CAR T-cells because the majority of patients will relapse over time.

Stem cell and tissue engineering approaches in pressure ulcer treatment

CONTEXT

Pressure ulcers or injuries, arise from ischemic damage to soft tissues induced by unrelieved pressure over a bony prominence. They are usually difficult to treat with standard medical therapy and often they recur. In the search for better treatment options, promising alternative forms of treatment are today emerging. Within the field of regenerative medicine, ongoing research on advanced therapies seeks to develop medicinal products based on gene therapy, somatic cell therapy, tissue-engineering and combinations of these.

OBJECTIVE

The main objective is to perform an overview of experimental and clinical developments in somatic cell therapy and tissue engineering targeting the treatment of pressure injuries.

METHODS

Searching terms as "PRESSURE ULCER", "STEM CELL THERAPY", "TISSUE ENGINEERING" or "WOUND HEALING" were used in combination or alone, including publications refered to basic and clinical research and focusing on articles showing results obtained in a clinical context. A total of 80 references are cited, including 23 references published in the 3 last years.

RESULTS

The results suggest that this form of treatment could be an interesting option in patients with difficult-to-treat ulcers as spinal cord injury patients.

CONCLUSION

This field of regenerative medicine is very broad and further research is warranted.

Inhibition of hexokinase 2 with 3-BrPA promotes MDSCs differentiation and immunosuppressive function

The adoptive transfer of ex vivo generated myeloid-derived suppressor cells (MDSCs) may be a promising therapeutic strategy for preventing allograft rejection after solid organ transplantation. Currently, the precise role of immune-metabolic pathways in the differentiation and function of MDSCs is not fully understood. Hexokinase 2 (HK2) is an isoform of hexokinase and is a key enzyme involved in the increased aerobic glycolysis of different immune cells during their activation and function. Here, we demonstrate that the addition of HK2 inhibitor 3-Bromopyruvic acid (3-BrPA) into traditional MDSCs induction system in vitro significantly promoted MDSCs production and enhanced their immunosuppressive function. Treatment with 3-BrPA increased the expression of MDSC-related immunosuppressive molecules, such as iNOS, Arg1, and CXCR2. Moreover, the adoptive transfer of 3-BrPA-treated MDSCs significantly prolonged the survival time of mouse heart allografts. This study provides a novel strategy to solve the problems of harvesting enough autologous cells for MDSC production from sick patients, and producing functionally enhanced MDSCs for preventing graft rejection and inducing tolerance.

How do I save cell therapy product's storage space?

BACKGROUND

Availability of liquid nitrogen (LN2) freezer storage space is a major challenge for many transplant programs as they continue to grow and accumulate products. The recent trend of allogeneic grafts cryopreservation that started during the COVID-19 pandemic, made the situation even worse requiring an increase in storage capacity. Multi-compartment cryopreservation bags can help save storage space but can be tricky to use. Here, we describe the validation of muti-compartment cryopreservation bags for the purpose of donor lymphocyte infusion (DLI) aliquots.

METHODS

We validated the use of five compartment cryobags for cryopreservation of cell therapy products. Four products were cryopreserved using these bags and each compartment was tested post-thaw for product volume distribution, total cell count recovery, and viability. Additionally, the integrity of both bag compartments and labels was assessed as well.

RESULTS

All tested specimens met post-thaw viability and TNC recovery acceptability criteria. Fill volume was optimized at 24-25 mL for acceptable volume distribution between aliquots. With proper heat sealing between compartments, all aliquots retain their integrity and cryopreservation labels were adherent and legible.

CONCLUSIONS

Muti-compartment bags can be used successfully for cryopreservation of cell therapy products and increase storage capacity.

The Choice of Either Conventional Chemotherapy or Inotuzumab Ozogamicin as Bridging Regimen Does Not Appear To Impact Clinical Response to CD19-Directed CAR-T Therapy in Pediatric B-ALL

Bridging therapy (BT) given during the period between T-cell collection and initiation of lymphodepleting chemotherapy is indicated for most children with B-cell acute lymphoblastic leukemia (B-ALL) undergoing treatment with tisagenlecleucel (tisa-cel), a CD19-directed chimeric antigen receptor T-cell (CAR-T) therapy. Both conventional chemotherapy agents and B-cell directed antibody-based therapies such as antibody-drug conjugates and bispecific T-cell engagers have been used as systemic forms of BT. The purpose of this retrospective study was to evaluate if there are detectable differences in clinical outcomes based on the type of BT given (conventional chemotherapy or inotuzumab). A retrospective analysis was performed on all patients treated with tisa-cel at Cincinnati Children's Hospital Medical Center for B-ALL with bone marrow disease (with or without extramedullary disease). Patients who did not receive systemic BT were excluded. Only 1 patient received blinatumomab as BT and was therefore not included in this analysis to focus the analysis on the use of inotuzumab. Pre-infusion characteristics and post-infusion outcomes were collected. Fisher's exact test was used for categorical variables, and t-test or Mann-Whitney test was used for continuous parametric and non-parametric variables respectively. Mantel-Cox was used for survival analyses. Thirty-two patients received BT before CD19 CAR-T for medullary leukemia; 24 received conventional chemotherapy, and 8 received inotuzumab ozogamicin (InO). Cohorts were evenly matched regarding CAR-T indication, recipient age, and median CAR-T cell dose. There were no significant differences between the groups for attaining a minimal residual disease (MRD)-negative complete response after CAR-T, the percentage of patients who maintained prolonged B-cell aplasia, or the median duration of B-cell aplasia. Thirty-seven percent of patients in the conventional chemotherapy group and 43% in the antibody-based therapy group relapsed, with a median time to relapse in both groups of 5 months. No differences in event-free survival, the cumulative incidence of relapse, or overall survival were seen between the two groups. Initial response to tisa-cel, relapse rate, and survival were similar between patients who received BT with conventional chemotherapy or InO therapy. Because low disease burden at the time of infusion is a positive prognostic factor, choice of bridging regimen should focus on therapy that is anticipated to effectively lower disease burden and minimize treatment-related toxicity. Given the limitations associated with the single center retrospective analysis, a larger, multicenter study is needed to further explore these findings.