Rapid T-cell chimerism switch and memory T-cell expansion are associated with pre-engraftment immune reaction early after cord blood transplantation

Serum cytokine profiles during engraftment syndrome and acute graft-versus-host disease in adult patients after hematopoietic stem cell transplantation

BACKGROUND

The underlying biology of engraftment syndrome (ES) following allogeneic hematopoietic stem cell transplantation (HSCT) is not fully elucidated, and the extent of its overlap with acute graft-versus-host disease (aGvHD) remains unclear. In order to establish potential indicator to distinguish ES more accurately, we conducted a retrospective analysis of cytokine levels during HSCT.

METHODS

A total of 121 consecutive adult patients who underwent HSCT were enrolled in this study. Blood samples for interleukin (IL)-2, IL-2R, IL-4, IL-5, IL-6, IL-8, IL-10, IL-1β, IL-12p70, interferon (IFN)-γ, IFN-α, tumor necrosis factor alpha (TNF-α) and C-reactive protein CRP were regularly assessed after transplantation and during transplantation related adverse events. Additionally, the balance of naïve, central memory and effector memory of CD4+ and CD8+ was analyzed around 30 and 60 days after stem cell infusion, respectively.

RESULTS

Thirty (24.79 %) and 33 (27.27 %) patients were diagnosed with ES and aGvHD, respectively. ES was characterized by a significant increase in level of IL-5, IL-6, IL-8 and sIL-2R, while aGvHD was associated with a significant upregulation of IL-6, IL-5, IL-10 and sIL-2R in the patients from grade I to grade IV. Notably, patients got much higher levels of IL-6, IL-5 and sIL-2R when developed to ES than to aGvHD. Moreover, a pronounced shift from naïve to memory cells, both in CD4+ and CD8+ subsets, was found in ES patients.

CONCLUSIONS

These findings suggest that cytokine profiles could serve as potential indicators for detecting and differentiating ES and aGvHD, enabling timely clinical intervention. Prospective clinical trials involving larger, independent patient cohorts are required to validate these observations.

Long-term lymphocyte subset number reconstitution is unique but comparable between umbilical cord blood and unrelated bone marrow transplantation

The number of umbilical cord blood transplantation (U-CBT) procedures has been growing annually, but little research has been done on long-term immune recovery after U-CBT. Infection risk is high in U-CBT recipients, and this can be partially attributed to immature immunocompetent cells in umbilical cord blood. In this study, we analyzed lymphocyte subset (LST) number to determine the long-term recovery timeline. We included 36 U-CBT and 10 unrelated bone marrow transplantation (U-BMT) recipients who survived more than 2 years after transplantation, and followed them for up to 10 years post-transplant. Recovery kinetics in the early phase post-transplant was different for each LST. Recovery of CD19+ B cells was faster after U-CBT than after U-BMT in the first 5 years after transplantation. Although CD4+ T cells increased in the first several months after U-CBT, long-term cell count recovery was impaired in approximately 20% of patients. Thus, although the LST recovery pattern after U-CBT was unique, LST number recovery was statistically comparable between U-CBT and U-BMT past 5 years post-transplantation.

Umbilical cord blood transplantation: Still growing and improving

Umbilical cord blood transplantation (UCBT) has been performed in the clinic for over 30 years. The biological and immunological characteristics of umbilical cord blood (UCB) have been re-recognized in recent years. UCB, previously considered medical waste, is rich in hematopoietic stem cells (HSCs), which are naïve and more energetic and more easily expanded than other stem cells. UCB has been identified as a reliable source of HSCs for allogeneic hematopoietic stem cell transplantation (allo-HSCT). UCBT has several advantages over other methods, including no harm to mothers and donors, an off-the-shelf product for urgent use, less stringent HLA match, lower incidence and severity of chronic graft-vs-host disease (GVHD), and probably a stronger graft-vs-leukemia effect, especially for minimal residual disease-positive patients before transplant. Recent studies have shown that the outcome of UCBT has been improved and is comparable to other types of allo-HSCT. Currently, UCBT is widely used in malignant, nonmalignant, hematological, congenital and metabolic diseases. The number of UCB banks and transplantation procedures increased exponentially before 2013. However, the number of UCBTs increased steadily in Asia and China but decreased in the United States and Europe year-on-year from 2013 to 2019. In this review, we focus on the development of UCBT over the past 30 years, the challenges it faces and the strategies for future improvement, including increasing UCB numbers, cord blood unit selection, conditioning regimens and GVHD prophylaxis for UCBT, and management of complications of UCBT.

Soluble Interleukin-2 Receptor Index Predicts Outcomes After Cord Blood Transplantation

BACKGROUND

Our previous study demonstrated that the soluble interleukin-2 receptor (sIL-2R) index, defined as the ratio of serum sIL-2R levels at neutrophil engraftment to that before conditioning, is a biomarker that can predict acute graft-vs-host disease (GVHD) after unrelated bone marrow transplantation. In the present study, we evaluated the significance of the sIL-2R index among patients who underwent cord blood transplantation (CBT).

METHODS

We retrospectively analyzed 31 patients who underwent single-unit CBT as their first transplantation for hematologic malignancies.

RESULTS

The median sIL-2R index was 4.2. The cumulative incidence of grade II to IV acute GVHD was not associated with the sIL-2R index. However, the cumulative incidence of relapse at 3 years after transplantation was significantly lower, with an sIL-2R index ≥ 3.7 than with an index < 3.7 (12.8% vs 50.0%; P = .04). As a result, the probability of overall survival at 3 years after transplantation was significantly higher in the former group than in the latter (79.8% vs 20.0%; P < .01). Only the dose of corticosteroid administered in the pre-engraftment period influenced the sIL-2 index.

CONCLUSION

The sIL-2R index can predict the incidence of relapse and probability of survival after CBT, possibly reflecting a graft-vs-leukemia effect.

Single cord blood transplantation in Japan; expanding the possibilities of CBT

Cord blood (CB) has been an alternative stem cell source for patients with a wide variety of hematological diseases. Cord blood confers the advantages of rapid availability and higher tolerance to two HLA antigen mismatches compared with unrelated donors, and this has increased opportunities for patients who do not have suitable donors or require urgent transplantation. Although the higher rate of engraftment failure remains a serious concern after cord blood transplantation (CBT), the mechanisms underlying this risk have gradually been clarified, which has helped to improve engraftment. Recent studies of CBT and other alternatives have reported comparable outcomes. Moreover, CBT shows promise even when patients are in a non-remission status, which may reflect the potent graft-versus-leukemia effect of CB. Here we compare the most recent outcomes of CBT with those of other stem cell sources and discuss the potential of CB and several outstanding issues that require resolution.

Development of Pre-Engraftment Syndrome, but Not Acute Graft-versus-Host Disease, Reduces Relapse Rate of Acute Myelogenous Leukemia after Single Cord Blood Transplantation

The different effects of pre-engraftment syndrome (PES) and acute graft-versus-host disease (aGVHD) on outcomes after cord blood transplantation (CBT) are unclear. We retrospectively evaluated the impact of PES and aGVHD on relapse and survival after single-unit CBT in 138 adult patients with hematologic malignancies at our institution between 2004 and 2016. Multivariate analysis demonstrated that development of grade III-IV aGVHD, particularly with gut or liver involvement, significantly contributed to higher nonrelapse mortality (P < .001), but PES and grade II-IV aGVHD did not. In subgroup analyses of underlying disease type, the development of PES had a significant effect on decreased relapse (P = .032) and better disease-free survival (DFS) (P = .046) in patients with acute myelogenous leukemia (AML). These data suggest that PES is associated with a reduced relapse rate and better DFS in AML, indicating that the early immune reaction before neutrophil engraftment may provide a unique graft-versus-leukemia effect after single-unit CBT.

Early lymphocyte recovery predicts clinical outcome after HSCT with mycophenolate mofetil prophylaxis in the Japanese population

Immune reconstitution affects clinical outcomes after allogeneic hematopoietic stem cell transplantation (HSCT), and it has been suggested that lymphocyte recovery affects survival after HSCT. However, few studies have examined lymphocyte recovery in Asian patients who received mycophenolate mofetil (MMF) prophylaxis for graft-versus-host disease. We retrospectively evaluated early lymphocyte recovery after HSCT among Japanese adults who received MMF prophylaxis. Patients were divided into two groups according to their median absolute lymphocyte count (ALC) on day 28 after HSCT as follows: the "low ALC group" (≤ 0.22 × 10⁹ cells/L) and the "high ALC group" (> 0.22 × 10⁹ cells/L). With a median follow-up of 317 days, the high ALC group showed significantly better overall survival than the low ALC group (at 1 year: 62 vs. 46%, P = 0.02). The high ALC group also tended to have better non-relapse mortality than the low ALC group (at 1 year: 13 vs. 23%, P = 0.08). There was no significant difference in relapse rate between the high and low ALC groups (at 1 year: 29 vs. 35%, P = 0.2). We conclude that among Japanese patients who received MMF prophylaxis, ALC on day 28 after HSCT was effective in predicting overall survival and non-relapse mortality.

Successful Secondary Umbilical Cord Blood Transplantation for Graft Failure in Acute Myelogenous Leukemia, Treated with Modified One-Day Conditioning Regimen, and Graft-Versus-Host Disease Prophylaxis Consisting of Mycophenolate and Tacrolimus

Although graft failure (GF) is a fatal and life-threatening complication of umbilical cord blood transplantation (CBT), the standard treatment has not been established. We describe the case of a 28-year-old man diagnosed with acute myelogenous leukemia with myelodysplasia-related changes harboring a normal karyotype. This patient underwent 2 courses of idarubicin and cytosine arabinose therapy, and 3 courses of high-dose cytosine arabinose therapy. Subsequently, he underwent high-dose chemotherapy (total body irradiation and cyclophosphamide) followed by first CBT. Primary GF occurred after post-immunological reaction and hemophagocytic lymphohistiocytosis, and was diagnosed on day 27 after the first CBT. Therefore, the patient underwent secondary CBT for GF treated with a modified one-day conditioning regimen consisting of fludarabine (30 mg/m(2), 3 days), cyclophosphamide (2 g/m(2)), and total body irradiation (2 Gy), and graft-versus-host disease prophylaxis consisting of mycophenolate and tacrolimus. Consequently, the patient achieved neutrophil engraftment on day 17 after the second CBT. During the clinical course of the second CBT, the main complications were sepsis, BK virus-associated cystitis, and acute graft-versus-host disease (skin, grade 2, stage 3). After these treatments, the patient was disease-free for 39 months. Our case suggests that these treatments may be feasible, safe, and effective for the treatment of patients with GF. This case study may be helpful to physicians who directly care for GF patients, and may provide a future direction for a more efficient treatment modality.

Complete donor T cell chimerism predicts lower relapse incidence after standard double umbilical cord blood reduced-intensity conditioning regimen allogeneic transplantation in adults

Double umbilical cord blood (dUCB) allogeneic transplantation after a low-dose total body irradiation, cyclophosphamide, and fludarabine (TCF)-based reduced-intensity conditioning regimen (RIC) is increasingly used in adults lacking a suitable related or unrelated donor. Currently, there are little data regarding the long-term outcome of CD3(+) T cell chimerism (TCC) in this particular setting. Thirty-six adults with various hematological diseases who received dUCB allogeneic transplants conditioned with TCF were included in this retrospective study. Peripheral blood CD3(+) TCC was considered until day +100 after transplantation to determine the impact of full versus mixed chimerism on long-term outcomes. Twenty-nine and 7 patients were documented with full and mixed CD3(+) TCC, respectively, within the first 100 days after transplantation. With a median follow-up of 36 months, 3 year-overall survival (OS), disease-free survival (DFS), and cumulative incidence of relapse (CIR) were 61%, (95% confidence interval [CI], 43% to 75%); 50% (95% CI, 32.5% to 66%), and 28% (95% CI, 16% to 44%), respectively. In univariate analysis, a full CD3(+) TCC was associated with a better 3-year DFS: 59% (95% CI, 39% to 75.5%) versus 14% (95% CI, 7% to 46%); hazard ratio (HR), .24 (.09 to .65); P = .005 and a lower CIR: 24% (95% CI, 21.5% to 57%) versus 78% (95% CI, 52% to 99%); HR, .18 (.05 to .50); P = .004. In multivariate analysis, a full CD3(+) TCC remained associated with a lower CIR (HR, .17 [.028 to .99]; P = .049). CD3(+) TCC has no impact on graft-versus-host disease and nonrelapse mortality in this study. In conclusion, here, full CD3(+) TCC was independently associated with a lower risk of relapse in adults receiving a dUCB TCF RIC allogeneic transplantation. This highlights the need to develop immunotherapy approaches allowing for early conversion to full chimerism after this type of transplantation.