Relapse in teenage and young adult patients treated on a paediatric minimal residual disease stratified ALL treatment protocol is associated with a poor outcome: results from UKALL2003

Multiple CAR-T cell therapy for acute B-cell lymphoblastic leukemia after hematopoietic stem cell transplantation: A case report

B-cell acute lymphoblastic leukemia (B-ALL) is the most common childhood malignancy. The cure rate has reached 90% after conventional chemotherapy and hematopoietic stem cell transplantation (HSCT), but the prognosis of patients with relapsed and refractory (R/R) leukemia is still poor after conventional treatment. Since FDA approved CD19 CAR-T cell (Kymriah) for the treatment of R/R B-ALL, increasing studies have been conducted on CAR-T cells for R/R ALL. Herein, we report the treatment of a patient with ALL who relapsed after allogeneic HSCT, had a complete remission (CR) to murine scFv CD19 CAR-T but relapsed 15 months later. Partial response was achieved after humanized CD19 CAR-T treatment, and the patient finally achieved disease-free survival after sequential CD22 CAR-T treatment. By comparing the treatment results of different CAR-T cells in the same patient, this case suggests that multiple CAR-T therapies are effective and safe in intramedullary and extramedullary recurrence in the same patient, and the expansion of CAR-T cells and the release of inflammatory cytokines are positively correlated with their efficacy. However, further clinical studies with large sample sizes are still needed for further clarification.

T cells targeted to TdT kill leukemic lymphoblasts while sparing normal lymphocytes

Unlike chimeric antigen receptors, T-cell receptors (TCRs) can recognize intracellular targets presented on human leukocyte antigen (HLA) molecules. Here we demonstrate that T cells expressing TCRs specific for peptides from the intracellular lymphoid-specific enzyme terminal deoxynucleotidyl transferase (TdT), presented in the context of HLA-A*02:01, specifically eliminate primary acute lymphoblastic leukemia (ALL) cells of T- and B-cell origin in vitro and in three mouse models of disseminated B-ALL. By contrast, the treatment spares normal peripheral T- and B-cell repertoires and normal myeloid cells in vitro, and in vivo in humanized mice. TdT is an attractive cancer target as it is highly and homogeneously expressed in 80-94% of B- and T-ALLs, but only transiently expressed during normal lymphoid differentiation, limiting on-target toxicity of TdT-specific T cells. TCR-modified T cells targeting TdT may be a promising immunotherapy for B-ALL and T-ALL that preserves normal lymphocytes.

An MRD-stratified pediatric protocol is as deliverable in adolescents and young adults as in children with ALL

Pediatric regimens have improved outcomes in adolescent and young adult (AYA) acute lymphoblastic leukemia (ALL). However, results remain inferior to children with ALL. The Australasian Leukaemia and Lymphoma Group (ALLG) ALL06 study (anzctr.org.au/ACTRN12611000814976) was designed to assess whether a pediatric ALL regimen (Australian and New Zealand Children's Haematology and Oncology Group [ANZCHOG] Study 8) could be administered to patients aged 15 to 39 years in a comparable time frame to children as assessed by the proportion of patients completing induction/consolidation and commencing the next phase of therapy (protocol M or high-risk [HR] treatment) by day 94. Minimal residual disease (MRD) response stratified patients to HR treatment and transplantation. From 2012 to 2018, a total of 86 patients were enrolled; 82 were eligible. Median age was 22 years (range, 16-38 years). Induction/consolidation was equally deliverable in ALL06 as in Study 8. In ALL06, 41.5% (95% confidence interval [CI], 30.7-52.9) commenced protocol M or HR therapy by day 94 vs 39.3% in Study 8 (P = .77). Median time to protocol M/HR treatment was 96 days (interquartile range, 87.5-103 days) in ALL06 vs 98 days in Study 8 (P = .80). Induction mortality was 3.6%. With a median follow-up of 44 months (1-96 months), estimated 3-year disease-free survival was 72.8% (95% CI, 62.8-82.7), and estimated 3-year overall survival was 74.9% (95% CI, 65.3-84.5). End induction/consolidation MRD negativity rate was 58.6%. Body mass index ≥30 kg/m2 and day 79 MRD positivity were associated with poorer disease-free survival and overall survival. Pediatric therapy was safe and as deliverable in AYA patients as in children with ALL. Intolerance of pediatric ALL induction/consolidation is not a major contributor to inferior outcomes in AYA ALL.

Efficient elimination of primary B-ALL cells in vitro and in vivo using a novel 4-1BB-based CAR targeting a membrane-distal CD22 epitope

Background

There are few therapeutic options available for patients with B-cell acute lymphoblastic leukemia (B-ALL) relapsing as CD19^– either after chemotherapy or CD19-targeted immunotherapies. CD22-chimeric antigen receptor (CAR) T cells represent an attractive addition to CD19-CAR T cell therapy because they will target both CD22⁺CD19^– B-ALL relapses and CD19^– preleukemic cells. However, the immune escape mechanisms from CD22-CAR T cells, and the potential contribution of the epitope binding of the anti-CD22 single-chain variable fragment (scFv) remain understudied.

Methods

Here, we have developed and comprehensively characterized a novel CD22-CAR (clone hCD22.7) targeting a membrane-distal CD22 epitope and tested its cytotoxic effects against B-ALL cells both in in vitro and in vivo assays.

Results

Conformational epitope mapping, cross-blocking, and molecular docking assays revealed that the hCD22.7 scFv is a high-affinity binding antibody which specifically binds to the ESTKDGKVP sequence, located in the Ig-like V-type domain, the most distal domain of CD22. We observed efficient killing of B-ALL cells in vitro, although the kinetics were dependent on the level of CD22 expression. Importantly, we show an efficient in vivo control of patients with B-ALL derived xenografts with diverse aggressiveness, coupled to long-term hCD22.7-CAR T cell persistence. Remaining leukemic cells at sacrifice maintained full expression of CD22, ruling out CAR pressure-mediated antigen loss. Finally, the immunogenicity capacity of this hCD22.7-scFv was very similar to that of other CD22 scFv previously used in adoptive T cell therapy.

Conclusions

We report a novel, high-affinity hCD22.7 scFv which targets a membrane-distal epitope of CD22. 4-1BB-based hCD22.7-CAR T cells efficiently eliminate clinically relevant B- CD22^high and CD22^low ALL primary samples in vitro and in vivo. Our study supports the clinical translation of this hCD22.7-CAR as either single or tandem CD22–CD19-CAR for both naive and anti-CD19-resistant patients with B-ALL.

The genomic landscape of teenage and young adult T-cell acute lymphoblastic leukemia

BACKGROUND

Treatment on risk adapted intensive pediatric protocols has improved outcome for teenagers and young adults (TYA) with T-cell acute lymphoblastic leukemia (T-ALL). Understanding the biology of disease in this age group and the genetic basis of relapse is a key goal as patients with relapsed/refractory disease have poor outcomes with conventional chemotherapy and novel molecular targets are required. This study examines the question of whether TYA T-ALL has a specific biological-molecular profile distinct from pediatric or adult T-ALL.

METHODS

Genomic characterization was undertaken of a retrospective discovery cohort of 80 patients aged 15-26 years with primary or relapsed T-ALL, using a combination of Genome-Wide Human SNP Array 6.0, targeted gene mutation and promoter methylation analyses. Findings were confirmed by MLPA, real-time quantitative PCR, and FISH. Whole Exome Sequencing was performed in 4 patients with matched presentation and relapse to model clonal evolution. A prevalence analysis was performed on a final data set of 1,792 individual cases to identify genetic lesions with age specific frequency patterns, including 972 pediatric (1-14 years), 439 TYA (15-24 years) and 381 adult (≥25 years) cases. These cases were extracted from 19 publications with comparable genomic data identified through a PubMed search.

RESULTS

Genomic characterization of this large cohort of TYA T-ALL patients identified recurrent isochromosome 7q i(7q) in our discovery cohort (n = 3). Prevalence analysis did not identify any age specific genetic abnormalities. Genomic analysis of 6 pairs of matched presentation - relapsed T-ALL established that all relapses were clonally related to the initial leukemia. Whole exome sequencing analysis revealed recurrent, targetable, mutations disrupting NOTCH, PI3K/AKT/mTOR, FLT3, NRAS as well as drug metabolism pathways.

CONCLUSIONS

All genetic aberrations in TYA T-ALL occurred with an incidence similar or intermediate to that reported in the pediatric and adult literature, demonstrating that overall TYA T-ALL exhibits a transitional genomic profile. Analysis of matched presentation - relapse supported the hypothesis that relapse is driven by the Darwinian evolution of sub-clones associated with drug resistance (NT5C2 and TP53 mutations) and re-iterative mutation of known key T-ALL drivers, including NOTCH1.

Cost-Effectiveness of Tisagenlecleucel in Paediatric Acute Lymphoblastic Leukaemia (pALL) and Adult Diffuse Large B-Cell Lymphoma (DLBCL) in Switzerland

INTRODUCTION

The purpose of the present analysis was to explore the cost-effectiveness of tisagenlecleucel in relapsed or refractory (r/r) paediatric acute lymphoblastic leukaemia (pALL) and r/r adult diffuse large B-cell lymphoma (DLBCL) in Switzerland against a range of historical standard-of-care treatments.

METHODS

Two cost-utility models were constructed for the two licensed indications using similar methodologies but indication-specific data. Clinical efficacy data were based on pooled analyses of clinical trials for tisagenlecleucel (pALL: ELIANA, ENSIGN, B2101J; DLBCL: JULIET, NCT02030834) and published data for comparator treatments. Treatment effects were compared based on matching-adjusted indirect comparison (MAIC) analyses. Four clinical lymphoma and leukaemia experts provided Switzerland-specific input regarding comparators, diagnostic and therapeutic procedures, clinical evidence and costs, which were used to inform the models. The base case analysis reflected the perspective of the Swiss mandatory health insurance system. Deterministic, probabilistic and scenario analyses were carried out to explore the robustness of results.

RESULTS

The base case analysis resulted in incremental costs of CHF 31,961-CHF 36,419 per quality-adjusted life year (QALY) gained for pALL across the different comparators and CHF 113,179 for DLBCL (1 CHF = 1.09 USD). Incremental costs per life-year gained ranged between CHF 33,906-CHF 97,399 across the two indications. Including productivity gains, tisagenlecleucel was shown to be dominant (more effective and less costly) over all the comparators for pALL and to result in incremental costs per life-year gained of CHF 57,324 for DLBCL.

CONCLUSION

Using hypothetical willingness-to-pay thresholds of CHF 100,000-150,000 per QALY gained, the present analysis has shown tisagenlecleucel to be a cost-effective treatment option in pALL and DLBCL.

Tisagenlecleucel for the Treatment of Relapsed or Refractory B-cell Acute Lymphoblastic Leukaemia in People Aged up to 25 Years: An Evidence Review Group Perspective of a NICE Single Technology Appraisal

As part of the National Institute for Health and Care Excellence's (NICE's) Single Technology Appraisal (STA) process, Novartis submitted evidence on the clinical effectiveness and cost-effectiveness of tisagenlecleucel for treating paediatric and young adult patients (under the age of 25 years) with relapsed or refractory (r/r) B-cell acute lymphoblastic leukaemia (ALL). This article presents a summary of the Evidence Review Group's (ERG's) independent review of the evidence submission, the committee's deliberations, and the subsequent development of NICE guidance for the use of tisagenlecleucel on the National Health Service (NHS) in England. Tisagenlecleucel is a chimeric antigen receptor-modified T-cell (CAR-T) product, the first of this emerging therapeutic class to be considered by NICE in this indication. The company's evidence submission was based upon three single-arm, phase II studies: ELIANA, ENSIGN, and B2101J. These trials demonstrated a beneficial effect of tisagenlecleucel, with significant extensions in event-free survival (EFS) and overall survival (OS) compared to historical control datasets on blinatumomab and salvage chemotherapy. Adverse events were common; 77% of patients suffered from cytokine release syndrome (CRS), 56% of whom required intensive care unit-level care. The ERG did not consider clofarabine monotherapy an appropriate proxy for salvage chemotherapy. The company presented a hybrid cost-effectiveness model, combining a decision tree and three-state partitioned survival model structure. The majority of quality-adjusted life-years (QALYs) gained were generated through additional life-years in the extrapolated 'long-term survival' phase of the model, where patients were assumed to be 'cured'. The ERG considered the results to be subject to substantial uncertainty, due in part to immature trial data, unresolved long-term treatment effects, and a lack of appropriate comparator data. The ERG implemented a number of changes to the company's model in an alternative base case, producing deterministic incremental cost-effectiveness ratios (ICERs) of £45,397 per QALY gained versus salvage chemotherapy, and £27,732 versus blinatumomab. The probabilistic model produced ICERs of £48,265 per QALY gained versus salvage chemotherapy, and £29,501 versus blinatumomab. The committee considered the ERG's analysis to be most closely aligned with their preferred assumptions, and did not consider tisagenlecleucel to meet both of the end-of-life (EoL) criteria. In recognition of the innovative nature of tisagenlecleucel, and the present immaturity of ongoing clinical trials, the committee considered further data collection would be valuable in resolving uncertainties around OS, the technology's novel mechanism of action, and the management of CRS and B-cell aplasia. The committee therefore recommended tisagenlecleucel for use in the Cancer Drugs Fund (CDF) until the conclusion of the ELIANA study (June 2023). This appraisal highlighted the difficulty of interpreting EoL criteria in the context of curative therapies and the valuation of cure versus extension of life. Further clarification of NICE's position in these situations may be necessary to ensure consistency and equity in their decision-making.

Prospective evaluation of minimal residual disease monitoring to predict prognosis of adult patients with Ph-negative acute lymphoblastic leukemia

OBJECTIVE

We investigated whether minimal residual disease (MRD) status in adult patients with Philadelphia chromosome (Ph)-negative acute lymphoblastic leukemia (ALL) is useful for decision on clinical indications for allogeneic hematopoietic stem cell transplantation (HSCT).

METHODS

We prospectively monitored MRD after induction and consolidation therapy in adult patients with Ph-negative ALL.

RESULTS

Among 103 adult ALL patients enrolled, 59 were Ph-negative, and MRD status was assessed in 51 patients. The probability of 3-year overall survival (OS) and disease-free survival (DFS) was 69% (95%CI 54-80) and 50% (95%CI 36-63), respectively. Patients who were MRD-negative after induction therapy (n = 15) had a significantly better 3-year DFS compared with those who were MRD-positive (n = 30; 73% vs 41%, P = 0.018). Patients who were MRD-positive after induction but became MRD-negative after consolidation chemotherapy C in the first course (n = 11) showed a significantly worse 3-year DFS compared with patients who were MRD-negative after induction chemotherapy A in the first course (45% vs 73%, P = 0.025).

CONCLUSIONS

These results indicate that DFS of about 70% can be expected in MRD-negative patients after induction therapy, and the patients did not benefit from HSCT in 1CR. This study was registered with the UMIN Clinical Trials Registry (UMIN-CTR), number UMIN000001519.

CD22 CAR T-cell therapy in refractory or relapsed B acute lymphoblastic leukemia

Despite worldwide promising clinical outcome of CD19 CAR-T therapy, relapse after this therapy is associated with poor prognosis and has become an urgent problem to be solved. We conducted a CD22 CAR T-cell therapy in 34 relapsed or refractory (r/r) B-ALL pediatric and adult patients who failed from previous CD19 CAR T-cell therapy. Complete remission (CR) or CR with incomplete count recovery (CRi) was achieved in 24 of 30 patients (80%) that could be evaluated on day 30 after infusion, which accounted for 70.5% of all 34 enrolled patients. Most patients only experienced mild cytokine-release syndrome and neurotoxicity. Seven CR patients received no further treatment, and 3 of them remained in remission at 6, 6.6, and 14 months after infusion. Eleven CR patients were promptly bridged to transplantation, and 8 of them remained in remission at 4.6 to 13.3 months after transplantation, resulted in 1-year leukemia-free survival rate of 71.6% (95% CI, 44.2-99.0). CD22 antigen loss or mutation was not observed to be associated with relapsed patients. Our study demonstrated that our CD22 CAR T-cells was highly effective in inducing remission in r/r B-ALL patients, and also provided a precious window for subsequent transplantation to achieve durable remission.