Efficacy and safety of porcine ALG compared to rabbit ATG as first-line treatment for children with acquired aplastic anemia

Porcine Anti-Lymphocyte Globulin, Cyclosporine A Plus Thrombopoietin Receptor Agonists Achieved Similar Efficacy and Survival Compared to Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Aplastic Anemia

Background

Immunosuppressive therapy (IST) with horse or rabbit anti-human thymocyte immunoglobulin (h-/r-ATG) and hematopoietic stem cell transplantation (HSCT) are two baseline treatments for severe aplastic anemia (SAA) and transfusion-dependent non-severe aplastic anemia (TD-NSAA) patients. Addition of thrombopoietin receptor agonists (TPO-RAs) to standard IST therapy (h-/r-ATG) has greatly improved the survival of SAA, whereas porcine anti-lymphocyte globulin (p-ALG) combined with TPO-RAs still had a matter of debate.

Methods

We retrospectively compared the data of 48 AA patients in our center between 2020 and 2022, 23 AA patients received with p-ALG ± TPO-RAs, 25 AA patients underwent matched sibling donor (MSD-) or haploidentical (haplo-) HSCT.

Results

For patients in the HSCT group, the ORR was 90.9% which was significantly higher than that in the IST±TPO-RAs group (45.5%, P = 0.001) at 3 months; moreover, patients who underwent HSCT achieved faster transfusion independence, better CR rate, shorter time of recovery normal blood routine, and the percentage of normal blood routine (all P < 0.05) compared with IST±TPO-RAs group. However, the ORR were similary at 6 months in the two groups (95.5% vs 81.8% P = 0.342), with a median follow up of 19.8 months (range, 0.3-38.2 months), the 2-year FFS and OS in the two cohorts has no different. Subgroup analysis further indicated that the 2-year FFS and OS were similar between IST+TPO-RAs and haplo-HSCT subgroups, as well as in IST+TPO-RAs and MSD-HSCT cohorts. Moreover, the first-time hospitalizations were much more expensive in the HSCT group than in the IST±TPO-RAs group (402 756 vs. 292 902 yuan, P = 0.002).

Conclusion

P-ALG-based-IST±TPO-RAs is a good treatment option with similar FFS and OS compared to allo- HSCT for AA patients without the opportunity of HSCT.

The state of the art in the treatment of severe aplastic anemia: immunotherapy and hematopoietic cell transplantation in children and adults

Acquired aplastic anemia (AA) is an immune-mediated bone marrow (BM) failure where marrow disruption is driven by a cytotoxic T-cell-mediated autoimmune attack against hematopoietic stem cells. The key diagnostic challenge in children, but also in adults, is to exclude the possible underlying congenital condition and myelodysplasia. The choice of treatment options, either allogeneic hematopoietic cell transplantation (alloHCT) or immunosuppressive therapy (IST), depends on the patient's age, comorbidities, and access to a suitable donor and effective therapeutic agents. Since 2022, horse antithymocyte globulin (hATG) has been available again in Europe and is recommended for IST as a more effective option than rabbit ATG. Therefore, an update on immunosuppressive strategies is warranted. Despite an improved response to the new immunosuppression protocols with hATG and eltrombopag, some patients are not cured or remain at risk of aplasia relapse or clonal evolution and require postponed alloHCT. The transplantation field has evolved, becoming safer and more accessible. Upfront alloHCT from unrelated donors is becoming a tempting option. With the use of posttransplant cyclophosphamide, haploidentical HCT offers promising outcomes also in AA. In this paper, we present the state of the art in the management of severe AA for pediatric and adult patients based on the available guidelines and recently published studies.

Predictive value of thyroid function in severe aplastic anemia patients treated with immunosuppressive therapy

To explore the predictive value of thyroid function in severe aplastic anemia (SAA) patients treated with immunosuppressive therapy (IST), 149 SAA patients in our center were enrolled between February 2015 and June 2020 in this study. We assessed the thyroid function of 134 patients without primary thyroid diseases, and discovered that 89 patients were accompanied by abnormal thyroid hormone, especially low triiodothyronine (T3). Patients with higher pretreatment-free T3 (FT3) levels (>5 pmol/L) demonstrated superior response rates at 3 and 6 months after IST compared to those with lower FT3 levels (54.5% vs 35.4%, P = .020; 67.3% vs 46.9%, P = .020). Multivariate analysis indicated that shorter disease duration (≤56 days) and response at 6 months were independent favorable factors of overall survival (relative risk [RR] = 2.66, 95% confidence interval [CI] = 1.03-6.90, P = .040; RR = 30.10, 95% CI = 4.02-225.66, P = .001). The 6-year failure-free survival (FFS) was 53.8% (95% CI = 40.9%-65.1%). Multivariate analysis revealed that patients with a response at 6 months, shorter duration (≤56 days) and receiving rabbit antithymocyte globulin (ATG) had better FFS outcomes than those without a response at 6 months, with a longer duration and receiving porcine ATG (RR = 22.6, 95% CI = 7.9-64.9, P < .001; RR = 2.4, 95% CI = 1.3-4.5, P = .006; RR = 2.5, 95% CI = 1.1-5.8, P = .030). In conclusion, FT3 levels reflect the severity of SAA, and patients with higher FT3 levels (>5 pmol/L) had superior response rates than those with lower ones.

Porcine anti-human lymphocyte immunoglobulin depletes the lymphocyte population to promote successful kidney transplantation

Introduction

Porcine anti-human lymphocyte immunoglobulin (pALG) has been used in kidney transplantation, but its impacts on the lymphocyte cell pool remain unclear.

Methods

We retrospectively analyzed 12 kidney transplant recipients receiving pALG, and additional recipients receiving rabbit anti-human thymocyte immunoglobulin (rATG), basiliximab, or no induction therapy as a comparison group.

Results

pALG showed high binding affinity to peripheral blood mononuclear cells (PBMCs) after administration, immediately depleting blood lymphocytes; an effect that was weaker than rATG but stronger than basiliximab. Single-cell sequencing analysis showed that pALG mainly influenced T cells and innate immune cells (mononuclear phagocytes and neutrophils). By analyzing immune cell subsets, we found that pALG moderately depleted CD4+T cells, CD8+T cells, regulatory T cells, and NKT cells and mildly inhibited dendritic cells. Serum inflammatory cytokines (IL-2, IL-6) were only moderately increased compared with rATG, which might be beneficial in terms of reducing the risk of untoward immune activation. During 3 months of follow-up, we found that all recipients and transplanted kidneys survived and showed good organ function recovery; there were no cases of rejection and a low rate of complications.

Discussion

In conclusion, pALG acts mainly by moderately depleting T cells and is thus a good candidate for induction therapy for kidney transplant recipients. The immunological features of pALG should be exploited for the development of individually-optimized induction therapies based on the needs of the transplant and the immune status of the patient, which is appropriate for non-high-risk recipients.

Antihuman T lymphocyte porcine immunoglobulin combined with cyclosporine as first-line immunosuppressive therapy for severe aplastic anemia in China: a large single-center, 10-year retrospective study

Background

Antihuman T lymphocyte porcine immunoglobulin (p-ATG) has been the most common ATG preparation in immunosuppressive therapy (IST) in Chinese patients with severe aplastic anemia (SAA) since 2009.

Objectives

This study aimed to evaluate the early hematologic response and long-term outcomes of a large cohort of patients with SAA who received p-ATG plus cyclosporine (CsA) as first-line therapy from 2010 to 2019.

Design

This is a single-center retrospective study of medical records.

Methods

We analyzed the data of 1023 consecutive patients with acquired aplastic anemia (AA) who underwent p-ATG combined with CsA as a first-line IST treatment from 2010 to 2019 at our department.

Results

The median age of the patients was 24 (4-75) years, and the median follow-up time was 57.2 months (3 days-137.5 months). There was an early mortality rate of 2.8% with a median death time of 0.9 months (3 days-2.9 months). The overall response rates were 40.6% and 56.1% at 3 and 6 months, respectively. The 5-year cumulative incidences of relapse and clonal evolution were 9.0% [95% confidence interval (CI) = 4.2-16.0%] and 4.5% (95% CI = 1.4-10.6%), respectively. The 5-year overall survival (OS) and event-free survival rates were 83.7% (95% CI = 81.1-86.0%) and 50.4% (95% CI = 47.1-53.5%), respectively.

Conclusion

p-ATG combined with CsA for the treatment of AA is effective and safe, and p-ATG can be used as an alternative ATG preparation for the standard IST regimen in areas in which h-ATG is not available.

Development and validation of early death risk score model for emergency status prediction in very severe aplastic anemia

This study developed and validated the Early Death Risk Score Model for early identification of emergency patients with very severe aplastic anemia (VSAA). All 377 patients with VSAA receiving first-line immunosuppressive therapy (IST) were categorized into training (n=252) and validation (n=125) cohorts. In the training cohort, age >24 years, absolute neutrophil count ≤0.015×10⁹/L, serum ferritin >900ng/mL and times of fever before IST >1 time were significantly associated with early death. Covariates were assigned scores and categorized as: low (score 0-4), medium (score 5-7) and high (score ≥8) risk. Early death rate was significantly different between risk groups and the validation cohort results were consistent with those of the training cohort. The area under the receiver operating characteristic curve for the model was 0.835 (0.734,0.936) in the training cohort and 0.862 (0.730,0.994) in the validation cohort. The calibration plots showed high agreement, and decision curve analysis showed good benefit in clinical applications. The VSAA Early Death Risk Score Model can help with early identification of emergency VSAA and optimize treatment strategies. Emergency VSAA with high risk is associated with high early death rate, and alternative donor hematopoietic stem cell transplantation could be a better treatment than IST even without HLA-matching.

New Trends of Nontransplant therapy for Acquired Aplastic Anemia

Aplastic anemia (AA) is a hematological disease that is characterized by pancytopenia and hypofunctional bone marrow hematopoiesis. Patients with AA are treated with either immunosuppressive therapy (IST) using anti-thymocyte globulin (ATG) and Cyclosporine (CsA) or hematopoietic stem cell transplantation (HSCT), if a matched donor is available. The standard IST regimen for AA patients which results in response rates up to 70%, and even higher overall survival. However, primary and secondary failures after IST remain frequent, and to date all attempts aiming to overcome this problem have been unfruitful. The nontransplant therapeutic options for AA have significantly expanded during the last few years. Here, we review the new trends of nontransplant therapy for AA and summarize the current therapeutic effect of AA.

Comparison of porcine ALG and rabbit ATG on outcomes of HLA-haploidentical hematopoietic stem cell transplantation for patients with acquired aplastic anemia

Objective

To evaluate the efficacy and safety of P-ALG (porcine anti-lymphocyte globulin) and R-ATG (rabbit anti-thymocyte globulin) in the conditioning regime for patients with acquired aplastic anemia who underwent HLA-haploidentical hematopoietic stem cell transplantation (halpo-HSCT).

Methods

A total of 91 patients with acquired aplastic anemia who received haplo-HSCT at our center between January 2014 and December 2020 were retrospectively reviewed. Twenty-eight patients were in the P-ALG group while sixty-three patients were in the R-ATG group.

Results

The median time was 11 versus 13 days (P = 0.294) for myeloid engraftment and 12.5 versus 15 days (P = 0.465) for platelet engraftment in the P-ALG and R-ATG groups, respectively. There were no significant difference in 5-year overall survival (74.83% ± 8.24% vs 72.29% ± 6.26%, P = 0.830), GVHD-free, failure-free survival (71.05% ± 8.65% vs 62.71% ± 6.22%, P = 0.662), failure-free survival (74.83% ± 8.24% vs 66.09% ± 5.84%, P = 0.647) and transplantation-related mortality (25.17% ± 8.24% vs 26.29% ± 6.22%, P = 0.708) between the two groups. The incidence of aGVHD (acute graft versus host disease) (65.39% ± 9.33% vs 62.71% ± 6.30%, P = 0.653), II–IV aGVHD (38.46% ± 9.54% vs 35.64% ± 6.24%, P = 0.695), III–IV aGVHD (19.23% ± 7.73% vs 10.53% ± 4.07%, P = 0.291), cGVHD (chronic graft versus host disease) (22.22% ± 12.25% vs 22.31% ± 6.30%, P = 0.915), and moderate to severe cGVHD (5.56% ± 5.40% vs 9.28% ± 4.46%, P = 0.993) were not significantly different. Similar outcomes were observed between the P-ALG and R-ATG groups for severe bacterial infection (17.9% vs 25.4%, P = 0.431), invasive fungal diseases (3.6% vs 9.5%, P = 0.577) and graft rejection (0% vs 9.5%, P = 0.218). However, the incidence of cytomegalovirus infection and Epstein-Barr virus infection was significantly lower in the P-ALG group (46.4% vs 71.4%, P = 0.022; 3.6% vs 25.4%, P = 0.014).

Conclusion

The efficacy and safety of P-ALG were similar with R-ATG in the setting of haplo-HSCT for patients with acquired aplastic anemia patients. P-ALG could be an alternative for R-ATG.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02410-z.

Efficacy and safety of immunosuppressive therapy with or without eltrombopag in pediatric patients with acquired aplastic anemia: A Chinese retrospective study

To determine the efficacy and safety of eltrombopag (E-PAG) combined with intensive immunosuppressive therapy (IST) for the treatment of pediatric patients with severe aplastic anemia (SAA). A total of 57 pediatric patients with newly diagnosed severe aplastic anemia were enrolled in this study. Thirty nine patients were treated with IST alone, consisting of porcine anti-human thymocyte globulin (30 mg/kg/day × 5 days) and cyclosporine A (CsA) (treated for 2 years, with a trough concentration maintained at 200-250 ng/mL), and 18 patients were treated with IST + E-PAG (12.5-50 mg/day, maintained for 6 months). We found no statistical difference between the response rates at 3 months for the two groups (CR: 12.8% vs. 22.2% p > 0.05, ORR: 56.4% vs. 77.7% p > 0.05). However, we found a statistical difference between the response rates at 6 months for the two groups (CR: 17.9% vs. 50% p < 0.05, ORR: 69.2% vs. 94.4% p < 0.05). The main side-effect during treatment with E-PAG was having a slightly to moderately elevated bilirubin level, which was temporary and controllable, accounting for approximately 66.6% (12/18) of patients in the IST + E-PAG group vs. 20.5% (8/39) of those in the IST group (p < 0.05). IST + E-PAG therapy appears to be more effective than IST alone for the treatment of pediatric SAA, with good tolerability and compliance. This approach deserves further exploration.

Clinical Outcome of Acquired Post-Immunosuppressive-Therapy Aplastic Anemia in Pediatric Patients: A 13-Year Experience in Two Southern China Tertiary Care Centers

Objective

The aim of the present study is to evaluate the efficacy, complications, and contributing factors of immunosuppressive therapy (IST) response in children with acquired aplastic anemia (AA) and to explore optimal therapeutic methods for different clinical AA types.

Methods

A total of 130 children diagnosed with acquired AA underwent IST in the Department of Pediatrics at Sun Yat-sen Memorial Hospital and the Department of Pediatrics at Seventh Affiliated Hospital, Sun Yat-sen University, between January 1, 2006, and July 15, 2020. The overall survival (OS), response rates, complications, and response predictors were analyzed. The response rates were compared according to clinical AA type.

Results

All 130 children with AA were followed up with for a median of 50.6 months. Among the patients, 25 had non-severe AA (NSAA), 64 had severe AA (SAA), and 41 had very severe AA (VSAA). All patients initially received IST. In 13 patients, the IST failed; these patients received an allo-hematopoietic stem cell transplant as a salvage regimen. The OS rate was 90.3% ± 2.8%, and the response rates at 3, 6, 9, and 12 months were 34.19%, 39.32%, 49.57%, and 66.67%, respectively. The prolonged follow-up period might have led to higher response rates, especially in patients with SAA and VSAA. A multivariate logistic regression analysis of prognostic factors was conducted; the results showed that high red blood cell (RBC) and platelet (PLT) counts were associated with a high overall response rate and that the RBC count at diagnosis is a major contributing factor.

Conclusion

With the use of rabbit anti-thymocyte globulin, proper cyclosporine management, and a prolonged IST follow-up period, a higher number of patients with acquired AA than normal achieved response. Proportionally, the number of patients who achieved remission within 12 months was higher in the SAA group (38.18%→63.64%) and VSAA group (28.95%→65.79%) than in the NSAA group (58.33%→75%). Higher RBC and PLT counts at diagnosis can predict a favorable outcome.