Current perspectives on resistance to chimeric antigen receptor T-cell therapy and strategies to improve efficacy in B-cell lymphoma.

Although chimeric antigen receptor (CAR) T-cell therapy has demonstrated remarkable efficacy in patients with chemo-refractory B-cell lymphoma, a significant portion is refractory or relapse. Resistance is a major barrier to improving treatment efficacy and long-term survival in CAR T-cell therapy, and clinicians have very limited tools to discriminate a priori patients who will or will not respond to treatment. While CD19-negative relapses due to loss of target antigen is well described, it accounts for only about 30% of cases with treatment failure. Recent efforts have shed light on mechanisms of CD19-positive relapse due to tumor intrinsic resistance, T-cell quality/manufacturing, or CAR T-cell exhaustion mediated by hostile tumor microenvironment. Here, we review the latest updates of preclinical and clinical trials to investigate the mechanisms of resistance and relapse post CAR T-cell therapy in B cell lymphoma and discuss novel treatment strategies to overcome resistance as well as advances that are useful for a CAR T therapist to optimize and personalize CAR T-cell therapy.

Cord blood-derived Vδ2+ and Vδ2- T cells acquire differential cell state compositions upon in vitro expansion.

Human cord blood-derived γδ T cells (CBγδ) display a highly diverse TCRγδ repertoire and have a unique subtype composition different from fetal or adult peripheral blood counterparts. We expanded CBγδ in vitro using an irradiated Epstein-Barr virus-transformed feeder cell-based modified rapid expansion protocol (REP). Single-cell RNA sequencing tracked progressive differentiation of naïve CBγδ into cells expressing neoantigen-reactive tumor-infiltrating lymphocyte as well as tissue-resident memory precursor-like and antigen-presenting cell-like gene signatures. TCRγδ clonal tracing revealed a bias toward cytotoxic effector differentiation in a much larger proportion of Vδ2- clones compared to Vδ2+ clones, resulting in the former being more cytotoxic at the population level. These clonotype-specific differentiation dynamics were not restricted to REP and were recapitulated upon secondary nonviral antigen stimulations. Thus, our data showed intrinsic cellular differences between major subtypes of human γδ T cells already in operation at early postnatal stage and highlighted key areas of consideration in optimizing cell manufacturing processes.

Conjunctival T Cell Profile in Allogeneic Hematopoietic Stem Cell Transplant Patients after Instilling Topical Cyclosporine-A 0.1% Cationic Emulsion.

INTRODUCTION: To profile conjunctival T cell populations in allogeneic hematopoietic stem cell transplant (HSCT) patients after instillation of daily topical cyclosporine-A (CsA) 0.1% cationic emulsion (Ikervis), and to evaluate patients' tolerance to these eye drops. METHODS: Nineteen participants were prescribed Ikervis prophylaxis once daily to both eyes from 3-5 weeks pre-HSCT to 12 months post-HSCT. The outcome measure was conjunctival T cell proportions from flow cytometry after impression cytology. Covariates included visual acuity, intraocular pressure, slit lamp and fundal examination, dry eye (SPEED) and quality of life questionnaires, non-invasive keratograph tear break-up time (NIKBUT), conjunctival redness, meibography, lipid thickness, Schirmer test, tear cytokines, fluorescein staining, tear osmolarity, and meibomian gland expressibility. RESULTS: The conjunctival T cell analysis showed either stable or decreased proportions of conjunctival CD4 T cells at the last visit from baseline in compliant patients. CD4 proportions were increased in non-compliant patients and in the single patient who developed ocular graft-versus-host disease (GVHD). All patients were tolerant to Ikervis but 6/19 were not compliant. In the majority of patients, vision did not affect activities of daily living. Pre- and post-HSCT up to the last study visit, there was no statistically significant change in clinical covariates. Only one participant developed ocular GVHD at 9 months post-HSCT. CONCLUSION: Superficial conjunctival T cell profile reflects compliance to daily topical Ikervis eye drops and clinical ocular surface parameters in allogenic HSCT patients. Tolerance is comparable to other formulations of topical CsA in the first 12 months. GOV IDENTIFIER: NCT04636918. URL: https://clinicaltrials.gov/ct2/show/NCT04636918?cond=ocular+Graft+Versus+Host+Disease&cntry=SG&draw=2&rank=2 .

A single-cell atlas identifies pretreatment features of primary imatinib resistance in chronic myeloid leukemia.

Primary resistance to tyrosine kinase inhibitors (TKIs) is a significant barrier to optimal outcomes in chronic myeloid leukemia (CML), but factors contributing to response heterogeneity remain unclear. Using single-cell RNA (scRNA) sequencing, we identified 8 statistically significant features in pretreatment bone marrow, which correlated with either sensitivity (major molecular response or MMR) or extreme resistance to imatinib (eventual blast crisis [BC] transformation). Employing machine-learning, we identified leukemic stem cell (LSC) and natural killer (NK) cell gene expression profiles predicting imatinib response with >80% accuracy, including no false positives for predicting BC. A canonical erythroid-specifying (TAL1/KLF1/GATA1) regulon was a hallmark of LSCs from patients with MMR and was associated with erythroid progenitor [ERP] expansion in vivo (P < .05), and a 2- to 10-fold (6.3-fold in group A vs 1.09-fold in group C) erythroid over myeloid bias in vitro. Notably, ERPs demonstrated exquisite TKI sensitivity compared with myeloid progenitors (P < .001). These LSC features were lost with progressive resistance, and MYC- and IRF1-driven inflammatory regulons were evident in patients who progressed to transformation. Patients with MMR also exhibited a 56-fold expansion (P < .01) of a normally rare subset of hyperfunctional adaptive-like NK cells, which diminished with progressive resistance, whereas patients destined for BC accumulated inhibitory NKG2A+ NK cells favoring NK cell tolerance. Finally, we developed antibody panels to validate our scRNA-seq findings. These panels may be useful for prospective studies of primary resistance, and in assessing the contribution of predetermined vs acquired factors in TKI response heterogeneity.

High-throughput telomere length measurement at nucleotide resolution using the PacBio high fidelity sequencing platform.

Telomeres are specialized nucleoprotein structures at the ends of linear chromosomes. The progressive shortening of steady-state telomere length in normal human somatic cells is a promising biomarker for age-associated diseases. However, there remain substantial challenges in quantifying telomere length due to the lack of high-throughput method with nucleotide resolution for individual telomere. Here, we describe a workflow to capture telomeres using newly designed telobaits in human culture cell lines as well as clinical patient samples and measure their length accurately at nucleotide resolution using single-molecule real-time (SMRT) sequencing. Our results also reveal the extreme heterogeneity of telomeric variant sequences (TVSs) that are dispersed throughout the telomere repeat region. The presence of TVSs disrupts the continuity of the canonical (5'-TTAGGG-3')n telomere repeats, which affects the binding of shelterin complexes at the chromosomal ends and telomere protection. These findings may have profound implications in human aging and diseases.

Favorable outcomes of COVID-19 in vaccinated hematopoietic stem cell transplant recipients: A single-center experience.

INTRODUCTION: A high incidence of mortality and severe COVID-19 infection was reported in hematopoietic stem cell transplant (HSCT) recipients during the early phases of the COVID-19 pandemic; however, outcomes with subsequent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, such as the omicron variant, have yet to be reported. Additionally, rollout of COVID-19 vaccinations in subsequent pandemic waves may modify COVID-19 disease severity and mortality in this immunocompromised population. We describe COVID-19 outcomes among a highly vaccinated population of HSCT recipients at a single center during successive waves of community transmission arising from the SARS-CoV-2 delta and omicron variants. METHODS: We retrospectively reviewed medical records of all HSCT recipients at our institution who tested positive for SARS-CoV-2 from May 2021 to May 2022. Descriptive statistics were reported; the chi-square test was utilized to identify factors associated with 90-day all-cause mortality and severity of COVID-19 infection. RESULTS: Over the 1-year study period, 77 HSCT recipients at our center contracted COVID-19 (43 allogenic; 34 autologous). Twenty-six (33.8%) patients were infected with the SARS-CoV-2 delta variant, while 51 (66.2%) had the SARS-CoV-2 omicron variant. Thirty-nine (50.6%) patients required hospitalization. More than 80% had received prior COVID-19 vaccination (57.1% with two doses, 27.3% with three doses). The majority (90.9%) had mild disease; only one (1.3%) patient required mechanical ventilation. Active hematological disease at time of COVID-19 infection was associated with increased odds of mortality [odds ratio (OR) = 6.90, 95% confidence interval (CI) = 1.20-40]. The 90-day all-cause mortality was 7.8% (six patients). Infection with the omicron variant (vs. delta) was associated with less severe illness (OR = 0.05, 95% CI = 0.01-0.47) and decreased odds of mortality (OR = 0.08, 95% CI = 0.01-0.76). Being on immunosuppression (OR = 5.10, 95% CI = 1.10-23.60) and being unvaccinated at disease onset (OR = 14.76, 95% CI = 2.89-75.4) were associated with greater severity of COVID-19 infection. CONCLUSION: We observed favorable outcomes with COVID-19 infection in a cohort of vaccinated HSCT patients. The SARS-CoV-2 omicron variant was associated with both less severe illness and decreased odds of mortality. As COVID-19 moves toward endemicity, early access to treatment and encouraging vaccination uptake is crucial in mitigating the challenge of COVID-19 management among HSCT recipients. Surveillance and assessment of clinical outcomes with new SARS-CoV-2 variants also remains important in this immunocompromised population.

Cost-Effectiveness and Budget Impact Analyses of Tisagenlecleucel in Pediatric and Young Adult Patients with Relapsed or Refractory B-Cell Acute Lymphoblastic Leukemia from the Singapore Healthcare System Perspective.

Purpose: Children and young adults with relapsed or refractory (r/r) acute lymphoblastic leukemia (ALL) have poor survival due to ineffective therapy options. The newly approved chimeric antigen receptor T-cell (CAR-T) therapy, tisagenlecleucel, has demonstrated improved survival but at a high up-front cost. The study aims to evaluate the cost-effectiveness and budget impact of tisagenlecleucel versus salvage chemotherapy regimen (SCR) or blinatumomab (BLN) for the treatment of pediatric and young adult patients with relapsed/refractory B-cell ALL from the Singapore healthcare system perspective. Patients and Methods: A three-health state partitioned survival model was constructed to analyze the cost-effectiveness of tisagenlecleucel vs SCR/BLN with/without allogenic hematopoietic stem cell transplantation (allo-HSCT) over a lifetime period. Clinical efficacy for tisagenlecleucel, SCR and BLN were based on pooled data from ELIANA, ENSIGN and B2101J trials, the study by von Stackelberg et al 2011, and MT103-205 respectively. Medical costs from pre-treatment until terminal care, including treatment, side effects, follow-up, subsequent allo-HSCT and relapse, were considered. Incremental cost-effectiveness ratios (ICERs) were estimated as the incremental costs per quality-adjusted life-year (QALY) gain. Additionally, the financial impact of tisagenlecleucel introduction in Singapore was estimated, comparing the present treatment scenario (without tisagenlecleucel) with a future scenario (with tisagenlecleucel), over 5 years. Results: In the base-case analysis, tisagenlecleucel treatment demonstrated cost-effectiveness with an ICER of S$45,840 (US$34,762) per QALY (vs SCR) and S$51,978 (US$39,315) per QALY (vs BLN). The estimated budget ranges from S$477,857 (US$361,438) to S$1.4 million (US$1.05 million) annually for the initial 5 years. Conclusion: Tisagenlecleucel is likely to be a cost-effective treatment option with limited budget implications while treating r/r ALL patients who have failed at least 2 lines of prior therapies.

Intraperitoneally Delivered Umbilical Cord Lining Mesenchymal Stromal Cells Improve Survival and Kidney Function in Murine Lupus via Myeloid Pathway Targeting.

To determine the therapeutic efficacy of human umbilical cord lining mesenchymal stromal cells (CL-MSCs) (US Patent number 9,737,568) in lupus-prone MRL/lpr (Faslpr) mice and elucidate its working mechanisms. A total of 4 doses of (20-25) × 106 cells/kg of CL-MSCs was given to 16-week-old female Faslpr mice by intraperitoneal injection. Three subsequent doses were given on 17 weeks, 18 weeks, and 22 weeks, respectively. Six-week-old Faslpr mice were used as disease pre-onset controls. Mice were monitored for 10 weeks. Mouse kidney function was evaluated by examining complement component 3 (C3) deposition, urinary albumin-to-creatinine ratio (ACR), and lupus nephritis (LN) activity and chronicity. Working mechanisms were elucidated by flow cytometry, Luminex/ELISA (detection of anti-dsDNA and isotype antibodies), and RNA sequencing. CL-MSCs improved mice survival and kidney function by reducing LN activity and chronicity and lymphocyte infiltration over 10 weeks. CL-MSCs also reduced urinary ACR, renal complement C3 deposition, anti-dsDNA, and isotype antibodies that include IgA, IgG1, IgG2a, IgG2b, and IgM. Immune and cytokine profiling demonstrated that CL-MSCs dampened inflammation by suppressing splenic neutrophils and monocytes/macrophages, reducing plasma IL-6, IL-12, and CXCL1 and stabilizing plasma interferon-γ and TNF-α. RNA sequencing further showed that CL-MSCs mediated immunomodulation via concerted action of pro-proinflammatory cytokine-induced chemokines and production of nitric oxide in macrophages. CL-MSCs may provide a novel myeloid (neutrophils and monocytes/macrophages)-targeting therapy for SLE.

Optimizing Blood Stem Cell Transplants Through Cellular Engineering.

Haematopoietic stem cell transplants (HSCT) are used in the treatment of blood cancers, autoimmune diseases, and metabolic disorders. Over 1.5 million transplants have been performed around the world thus far. In an attempt to enhance the efficacy of the cells used for transplantation, efforts are underway to use cellular engineering to increase cell numbers through: (1) the expansion of hematopoietic stem and progenitor cells (HSPC); (2) cellular subset selection to remove cells that cause graft-versus-host disease (GvHD), while adding back cells, which can mediate anti-tumor and anti-viral immunity; (3) the use of immune regulatory cells, such as mesenchymal stromal cells (MSC) and regulatory T cells (Tregs) to control GvHD; (4) the use of immune effector cells to mount immunological control of tumor cells before, after, or independent of blood stem cell transplants.

Cost-effectiveness and budget impact analyses of tisagenlecleucel in adult patients with relapsed or refractory diffuse large B-cell lymphoma from Singapore's private insurance payer's perspective.

BACKGROUND: Patients experiencing relapsed or refractory diffuse large B-cell lymphoma (r/r DLBCL) have limited treatment options and poor prognosis. Tisagenlecleucel (TIS) has shown improved clinical outcomes, but at a high upfront cost. Singapore has a multi-payer healthcare system where private insurance is one of the major payers. This study evaluated the cost-effectiveness and budget impact of TIS against salvage chemotherapy regimen (SCR) for treating r/r DLBCL patients who have failed ≥2 lines of systemic therapy from Singapore's private insurance payer's perspective. METHODS: Over a life-time horizon, a partitioned survival model with three health-states was developed to evaluate the cost-effectiveness of TIS vs. SCR with or without hematopoietic stem cell transplantation (HSCT). Efficacy inputs for TIS and SCR were based on 43 months of observation data from pooled JULIET and UPenn trials, and CORAL extension studies respectively. Direct costs for pre-treatment, treatment, adverse events, follow-up, subsequent-HSCT, relapse, and terminal care were included. Incremental cost-effectiveness ratios (ICERs) were calculated as the total incremental costs per quality-adjusted life-year (QALY) gained. Additionally, the financial implication of introducing TIS in Singapore from a private payer's perspective was analyzed, comparing the current treatment pathway (without TIS) with a future scenario (with TIS) over 5 years. RESULTS: Compared with SCR, TIS was the dominant option, with cost savings of S$8,477 alongside an additional gain of 2.78 QALYs in privately insured patients who shifted from private to public hospitals for TIS treatment. Scenario analyses for patients starting in public hospitals show ICERs of S$99,623 (no subsidy) and S$133,261 (50% subsidy for SCR treatment, no subsidy for TIS), supporting the base case. The projected annual budget impact ranges from S$850,000 to S$3.4 million during the first 5 years. CONCLUSIONS: TIS for treating r/r DLBCL patients who have failed ≥2 lines of systemic therapies, is likely to be cost effective with limited budget impact.

Understanding the Psychological Impact of COVID-19 Pandemic on Patients With Cancer, Their Caregivers, and Health Care Workers in Singapore.

PURPOSE: The coronavirus disease 2019 (COVID-19) pandemic has had a global impact, and Singapore has seen 33,000 confirmed cases. Patients with cancer, their caregivers, and health care workers (HCWs) need to balance the challenges associated with COVID-19 while ensuring that cancer care is not compromised. This study aimed to evaluate the psychological effect of COVID-19 on these groups and the prevalence of burnout among HCWs. METHODS: A cross-sectional survey of patients, caregivers, and HCWs at the National Cancer Centre Singapore was performed over 17 days during the lockdown. The Generalized Anxiety Disorder-7 and Maslach Burnout Inventory were used to assess for anxiety and burnout, respectively. Self-reported fears related to COVID-19 were collected. RESULTS: A total of 624 patients, 408 caregivers, and 421 HCWs participated in the study, with a response rate of 84%, 88%, and 92% respectively. Sixty-six percent of patients, 72.8% of caregivers, and 41.6% of HCWs reported a high level of fear from COVID-19. The top concern of patients was the wide community spread of COVID-19. Caregivers were primarily worried about patients dying alone. HCWs were most worried about the relatively mild symptoms of COVID-19. The prevalence of anxiety was 19.1%, 22.5%, and 14.0% for patients, caregivers, and HCWs, respectively. Patients who were nongraduates and married, and caregivers who were married were more anxious. The prevalence of burnout in HCWs was 43.5%, with more anxious and fearful HCWs reporting higher burnout rates. CONCLUSION: Fears and anxiety related to COVID-19 are high. Burnout among HCWs is similar to rates reported prepandemic. An individualized approach to target the specific fears of each group will be crucial to maintain the well-being of these vulnerable groups and prevent burnout of HCWs.

Cost utility analysis of tisagenlecleucel vs salvage chemotherapy in the treatment of relapsed/refractory diffuse large B-cell lymphoma from Singapore's healthcare system perspective.

BACKGROUND: Patients with relapsed or refractory diffuse large B-cell lymphoma (r/r DLBCL) have limited treatment options and poor prognoses. Tisagenlecleucel, a chimeric antigen receptor (CAR) T-cell therapy has shown early promise in improving survival outcomes, but at a high upfront cost. This study evaluated the cost-effectiveness of tisagenlecleucel versus salvage chemotherapy for treating patients with r/r DLBCL who have failed at least 2 lines of systemic therapies. METHODS: A hybrid decision tree and three-state partitioned survival model (progression-free (PF), progressive disease and death) was developed from the Singapore healthcare payer perspective. Survival curves from JULIET trial and CORAL-1 extension study were extrapolated beyond trial period over a 15-year time horizon to estimate the underlying progression-free survival and overall survival parametric distributions for both arms. Health state utilities were retrieved from the literature, and direct costs were sourced from public healthcare institutions in Singapore. One-way probabilistic sensitivity analyses and scenario analyses were conducted to explore the impact of uncertainties and assumptions on cost-effectiveness results. RESULTS: Compared with salvage chemotherapy, tisagenlecleucel was associated with a base-case incremental cost-effectiveness ratio (ICER) US$508,530 (S$686,516) per quality adjusted life year (QALY) gained and US$320,200 (S$432,269) per life year (LY) gained. One-way sensitivity analysis showed the ICER was most sensitive to time horizon, PF utility and cost of tisagenlecleucel. Scenario analyses confirmed that the ICERs remained high under favorable assumptions and substantial price reduction was required to reduce the ICER. CONCLUSIONS: Our analysis showed tisagenlecleucel use in r/r DLBCL patients who failed at least 2 prior lines of systemic therapies was associated with exceedingly high ICER, which is unlikely to represent good use of healthcare resources. Comparative clinical evidence from the ongoing trials might provide more insight into future evaluations.

Minimizing transmission of COVID-19 while delivering optimal cancer care in a National Cancer Centre.

The COVID-19 pandemic has disrupted current models of healthcare and adaptations will likely continue. With the gradual easing of lockdown measures worldwide, cancer centres must be prepared to implement novel means to prevent repeated waves of infection. There are two limitations unique to oncology - a higher susceptibility of patients to COVID-19 and the multidisciplinary approach required of cancer management. We describe the measures implemented in the largest cancer centre in Singapore to continue optimal cancer care in spite of the ongoing pandemic, with no nosocomial infections reported in our centre to date. We adopted a multipronged approach, with an overall committee supervising the entire COVID-19 management effort. A screening clinic was setup to triage patients prior to entry to the centre. Each Oncology Division within the cancer centre designed solutions tailored to the specific needs of their discipline. We explore in detail the screening criteria and workflow of the screening clinic, as well as modifications by individual divisions to reduce infection risk to patients and healthcare professionals. This approach can be modelled by other cancer centres during this prolonged COVID-19 pandemic.

An Asian Body to Tackle Cancers in Asia - The Asian National Cancer Centers Alliance.

The socioeconomic burden of cancer is growing rapidly in the Asian region, with a concentrated burden on low- and middle- income countries. The residents of this region, representing almost 60% of the global population, demonstrate an eclectic and complex nature, with huge disparities in ethnicity, sociocultural practices among others. The Asian National Cancer Centers Alliance (ANCCA) was established in 2005 by heads of several national cancer centers (NCCs) in the region to address common issues and concerns among Asian countries. During the first 13 years of ANCCA's existence, the participating NCCs' senior managers paved the way toward collaboration through transparent sharing of key facts and activities. Concrete achievements of the Alliance include the Asia Tobacco-Free Declaration, the establishment of the ANCCA Constitution in 2014 as well as the creation of an official website more recently. In November 2019, the most active ANCCA members (China, India, Indonesia, Japan, Korea, Mongolia, Singapore, Thailand, and Vietnam) strengthened the bonds of the entity with the clear aim to halt the increase in cancer and mortality rates in Asian countries by 2030. New opportunities including accelerated cooperation between members as well as collaboration with external and multidisciplinary stakeholders at local, regional and international levels are an essential step to most effectively tackle cancers in Asia.

Recommendations to improve the clinical adoption of NGS-based cancer diagnostics in Singapore.

Next-generation sequencing (NGS)-based diagnostics have demonstrated clinical utility in predicting improved survival benefits with targeted treatment in certain cancer types, and positive cost-benefit in several healthcare systems. However, clinical adoption in Singapore remains low despite commercial availability of these diagnostics. This expert opinion review examines the key challenges to the clinical adoption of NGS-based diagnostics in Singapore, provides recommendations on impactful initiatives to improve adoption, and also offers practical guidance on specific cancer types in which NGS-based diagnostics are appropriate for use in Singapore. Limited patient affordability is one major challenge to clinical adoption of NGS-based diagnostics, which could be improved by enabling patient access to more funds for specific cancer types with clear benefits. Expert opinion based on current evidence and clinical experience supports the upfront use of hotspot panels in advanced non-small cell lung cancer (NSCLC), metastatic colorectal cancer, advanced and recurrent ovarian cancer, and acute myeloid leukemia. Comprehensive genomic profiling could be considered for upfront use in select patients with NSCLC and ovarian cancer, or in refractory patients with the four cancer types. Wider adoption of NGS-based diagnostics will improve the delivery of cancer care in Singapore and Asia-Pacific, and thus lead to better patient outcomes.

Large-Scale Whole-Genome Sequencing of Three Diverse Asian Populations in Singapore.

Underrepresentation of Asian genomes has hindered population and medical genetics research on Asians, leading to population disparities in precision medicine. By whole-genome sequencing of 4,810 Singapore Chinese, Malays, and Indians, we found 98.3 million SNPs and small insertions or deletions, over half of which are novel. Population structure analysis demonstrated great representation of Asian genetic diversity by three ethnicities in Singapore and revealed a Malay-related novel ancestry component. Furthermore, demographic inference suggested that Malays split from Chinese ∼24,800 years ago and experienced significant admixture with East Asians ∼1,700 years ago, coinciding with the Austronesian expansion. Additionally, we identified 20 candidate loci for natural selection, 14 of which harbored robust associations with complex traits and diseases. Finally, we show that our data can substantially improve genotype imputation in diverse Asian and Oceanian populations. These results highlight the value of our data as a resource to empower human genetics discovery across broad geographic regions.