Role of allogeneic haematopoietic stem cell transplantation in the treatment of adult acute lymphoblastic leukaemia in the era of immunotherapy

Chimeric antigen receptor-immune cells against solid tumors: Structures, mechanisms, recent advances, and future developments

ABSTRACT

The advent of chimeric antigen receptor (CAR)-T cell immunotherapies has led to breakthroughs in the treatment of hematological malignancies. However, their success in treating solid tumors has been limited. CAR-natural killer (NK) cells have several advantages over CAR-T cells because NK cells can be made from pre-existing cell lines or allogeneic NK cells with a mismatched major histocompatibility complex (MHC), which means they are more likely to become an "off-the-shelf" product. Moreover, they can kill cancer cells via CAR-dependent/independent pathways and have limited toxicity. Macrophages are the most malleable immune cells in the body. These cells can efficiently infiltrate into tumors and are present in large numbers in tumor microenvironments (TMEs). Importantly, CAR-macrophages (CAR-Ms) have recently yielded exciting preclinical results in several solid tumors. Nevertheless, CAR-T, CAR-NK, and CAR-M all have their own advantages and limitations. In this review, we systematically discuss the current status, progress, and the major hurdles of CAR-T cells, CAR-NK cells, and CAR-M as they relate to five aspects: CAR structure, therapeutic mechanisms, the latest research progress, current challenges and solutions, and comparison according to the existing research in order to provide a reasonable option for treating solid tumors in the future.

Prognostic factors impacting post-transplant outcomes in adult T-cell acute lymphoblastic leukemia: a registry-based study by the EBMT acute leukemia working party

T-cell acute lymphoblastic leukemia (T-ALL) predominantly affects individuals in late childhood and young adulthood. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative modality particularly in the setting of poor risk genetics and/or persistent minimal residual disease. Limited studies have directly explored the impact of patient- and transplant-related factors on post-transplant outcomes in T-ALL. Using a large dataset from the European Society for Blood and Marrow Transplantation registry, we identified 1907 adult T-ALL patients (70% male) who underwent their first allo-HSCT in first complete remission (CR1) from matched sibling donors (MSD; 45%), unrelated donors (UD; 43%) or haploidentical donors (12%) between 2010 and 2021. The median age at transplant was 33.4 years (18.1-75). The median follow up was 2.9 years. Most patients underwent total body irradiation (TBI)-based myeloablative conditioning (69%). The 2-year overall survival (OS) was 69.4%, and leukemia -free survival (LFS) was 62.1%. In multivariate analysis, advanced age at transplant negatively affected LFS (for each 10-year increment, HR = 1.11, p = 0.004), GVHD-free, relapse-free survival (GRFS) (HR = 1.06, p = 0.04), OS (HR = 1.12, p = 0.002), and non-relapse mortality (NRM) (HR = 1.23, p < 0.001). More recent years of allo-HSCT were associated with improved GFRS (For each 3-year increment, HR = 0.89, p < 0.001), OS (HR = 0.9, p = 0.02), and decreased NRM (HR = 0.82, p = 0.008). TBI improved LFS. (HR = 0.79, p = 0.02), GRFS (HR = 0.83, p = 0.04), and relapse incidence (RI) (HR = 0.65, p < 0.001). Female-to-male transplant negatively affected GRFS (HR = 1.21, p = 0.02) and OS (HR = 1.23, p = 0.048). In vivo T-cell depletion significantly improved GFRS (HR = 0.74, p < 0.001). This large study identified prognostic factors, such as age at transplant conditioning regimen, in influencing post-transplant in adult T-ALL patients undergoing allo-HSCT. Importantly, a significant improvement over time was noted. These findings hold great promise for new adapted treatment strategies and can serve as a benchmark for future studies in that setting.

Phenotypes and Lung Microbiota Signatures of Immunocompromised Patients with Pneumonia-Related Acute Respiratory Distress Syndrome

Objective

We aim to identify the clinical phenotypes of immunocompromised patients with pneumonia-related ARDS, to investigate the lung microbiota signatures and the outcomes of different phenotypes, and finally, to develop a machine learning classifier for a specified phenotype.

Methods

This prospective study included immunocompromised patients with pneumonia-related ARDS. We identified phenotypes using hierarchical clustering to analyze clinical variables and serum cytokine levels. We then compared outcomes and lung microbiota signatures between phenotypes. Based on lung microbiota markers, we developed a random forest classifier for a specified phenotype with worse outcomes.

Results

This study included 92 patients, who were divided into three phenotypes, namely "type α" (N = 33), "type β" (N = 12), and "type γ" (N = 47). Compared to type α or type β, patients with type γ had no obvious inflammatory presentation and had significantly lower IL-6 levels and more severe oxygenation failure. Type γ was also related to higher 30-day mortality and lower ventilator free days. The microbiota signatures of type γ were characterized by lower alpha diversity and distinct compositions than those of other patients. We developed a lung microbiota-derived random forest model to differentiate patients with type γ from other phenotypes.

Conclusion

Immunocompromised patients with pneumonia-related ARDS can be clustered into three clinical phenotypes, namely type α, type β, and type γ. Phenotypes were distinguished from each other with different outcomes and lung microbiota signatures. Type γ, which was characterized by insufficient inflammation response and worse outcomes, can be detected with a random forest model based on lung microbiota markers.

Construction of CD19 targeted dual- and enhanced dual-antibodies and their efficiency in the treatment of B cell malignancy

BACKGROUND

T cell-redirecting bispecific antibodies establish a connection between endogenous T cells and tumor cells, activating T cells function to eliminate tumor cells without ex vivo genetic alteration or manipulation. Here, we developed a novel dual-specific antibody (DuAb) and an enhanced DuAb (EDuAb) with different stimulation signal to activate T cells, and evaluated their impact on the treatment of acute lymphoblastic leukemia (ALL).

METHODS

The expression plasmids of the DuAb and EDuAb containing CD80 molecule were constructed by cloning heavy chain and light chain variable fragments from anti-human CD19 (HI19a) and CD3 (HIT3a) monoclonal antibody hybridomas, respectively. The activation and the anti-tumor efficacy of human T cells mediated by DuAb and EDuAb were evaluated in vitro. B-cell ALL xenograft NSG mouse model was established to investigate the therapeutic effect in vivo.

RESULTS

EDuAb promoted the optimal expansion of primary human T cells with low expression of inhibitory markers in vitro than DuAb did. Both DuAb and EDuAb showed a similar capability in inducing healthy donor T cells to specifically eliminate B-ALL cell lines and primary blasts from patients. The similar ability was also observed in the patient-derived T cells. In vivo study showed that both DuAb and EDuAb significantly alleviated tumor burden and extended survival of B-ALL xenograft NSG mice. The median survival of PBS, DuAb and EDuAb treatment groups were 27, 38 and 45 days, respectively. The phenotype of T cells and cytokine release in peripheral blood (PB) of B-ALL xenograft NSG mice on day 24 were analyzed as well. The results showed that the proportion of CD8⁺ T cells and cytokine levels, including IL-2, IFN-γ and TNF-α, were higher in the EDuAb group than that of DuAb. Moreover, both DuAb and EDuAb significantly decreased the residual leukemia cells in PB of B-ALL xenograft NSG mice.

CONCLUSIONS

Both DuAb and EDuAb showed great potential as novel treatments for B-ALL in clinical applications. However, compared to DuAb, EDuAb showed a significant advantage in promoting the proliferation and survival of T cells. Furthermore, EDuAb showed a better promising effect on eliminating tumor cells and extending survival in vivo, which provides new insights for the development of new multi-specific antibodies.

Outcomes of allogeneic or autologous stem cell transplantation followed by maintenance chemotherapy in adult patient with B-ALL in CR1 with no detectable minimal residual disease

Autologous haematopoietic stem cell transplantation (auto-HSCT) as a treatment for B-cell acute lymphoblastic leukaemia (B-ALL) has been rigorously debated in recent years. We retrospectively analysed the outcomes of 355 adult patients with B-ALL in first complete remission who had received auto-HSCT or allogeneic HSCT (allo-HSCT) in our centre. The treatment efficacy was evaluated from a model stratified on the risk classification and minimal residue disease (MRD) status after three chemotherapy cycles. Auto-HSCT demonstrated comparable 3-year overall survival (OS) (72.7% vs. 68.5%, p = 0.441) and leukaemia-free survival rates (62.8% vs. 56.1%, p = 0.383) compared to allo-HSCT for patients with negative MRD, while the advantage of lower non-relapse mortality (1.5% vs. 25.1%, p < 0.001) was offset by a higher cumulative incidence of relapse (CIR) rates (35.7% vs. 18.9%, p = 0.018), especially in high-risk patients. For patients at high risk and with positive MRD, there was a lower trend of 3-year OS (50.0% vs. 66.0%, p = 0.078) and significantly higher CIR rates (71.4% vs. 39.1%, p = 0.018) in auto-HSCT. However, no significant interaction was observed in the tests. In conclusion, auto-HSCT appears to be an attractive treatment for patients with negative MRD after three chemotherapy cycles. For MRD-positive patients, allo-HSCT may be a more effective treatment.

Current status and prospects of hematopoietic stem cell transplantation in China

Hematopoietic stem cell transplantation (HSCT) is a highly effective and unique medical procedure for the treatment of most hematological malignancies. The first allogeneic transplantation was performed by E. Donnall Thomas in 1957. Since then, the field has evolved and expanded worldwide. The first successful allogenic HSCT (allo-HSCT) in China was conducted in 1981. Although the development of allo-HSCT in China lagged, China has since made considerable contributions to the process of HSCT worldwide, with more than 10,000 HSCTs performed annually. In particular, haploid HSCT (haplo-HSCT) technology represented in the Beijing Protocol has demonstrated similar efficacy to human leukocyte antigen-matched HSCT and has gradually become the pre-dominant choice for allo-HSCT in China. Currently, the number of haplo-HSCT procedures exceeds 5000 per year, and the Beijing Protocol has been greatly improved by implementing updated individualized strategies for controlling complications, relapse, and infection management. In addition, innovative haplo-HSCT technologies developed by different medical transplantation centers, such as Soochow, Zhejiang, Fujian, Chongqing, and Anhui, have emerged, providing inspiration for the refinement of global practice. This review will focus on the current activity in this field and highlight important trends that are vital in China's allo-HSCT process, examining the current viewpoint and future directions.