Impact of Single-Dose Plerixafor as an Adjunct to Granulocyte Colony-Stimulating Factor-Based Peripheral Blood Stem Cell Mobilization on the Graft Composition and Outcome for T Cell-Replete Haploidentical Peripheral Blood Stem Cell Transplantation with Post-Transplantation Cyclophosphamide: A Comparative Study

Long-Term Follow-Up of Abatacept, Post-Transplantation Cyclophosphamide, and Sirolimus-Based Haploidentical Transplantation in Younger Patients with Nonmalignant Diseases

Haploidentical (haplo) hematopoietic cell transplantation (HCT) for nonmalignant disease (NMD) carries inherent challenges of both alloreactivity and graft failure. Building on promising results from pilot studies in which abatacept was combined with post-transplantation cyclophosphamide (PTCy) and sirolimus (AbaCyS) in younger NMD patients undergoing haplo-HCT, we present the long-term outcomes of this protocol. On the back of uniform disease-specific conditioning regimens containing antithymocyte globulin 4.5 mg/kg from day -9 to day -7, GVHD prophylaxis with AbaCyS consisted of abatacept administered on days 0, +5, +20, +35, and monthly until 180 days with PTCy and sirolimus. The patients were followed up with longitudinal assessment of immune reconstitution, growth, and reproductive development and quality of life (QoL) analyses. Among 40 patients (aplastic anemia, n = 24; hemoglobinopathies, n = 14; and primary immunodeficiencies, n = 2) with a median age of 10 years (range, 2 to 25 years), 95% achieved sustained engraftment. Post-transplantation hemophagocytic syndrome was detected in 3 patients, leading to graft failure in 2 cases. The incidence of acute graft-versus-host disease (GVHD) was 2.6%, and that of chronic GVHD (cGVHD) was 14.3%. Cytomegalovirus, adenovirus, and Epstein-Barr virus infections were observed in 45%, 5%, and 0% respectively. Rates of nonrelapse mortality, overall survival, event-free survival, and GVHD-free, event-free survival were 5%, 95%, 90%, and 82%, respectively, at a median follow-up of 4.6 years. Absence of cGVHD correlated with younger patient age and early sustained recovery of regulatory T cells and mature natural killer cells, which in turn was associated with improved QoL and lack of late infections. The AbaCyS protocol was associated with excellent long-term survival, with attenuation of both early and late alloreactivity in >80% of younger patients undergoing haplo-HCT for NMD. This study sheds light on predispositions to cGVHD and its impact on QoL, warranting further optimization of this approach.

Take a spin: Apheresis in the care of adult leukaemia patients

Apheresis is an automated process to separate the whole blood of a patient or a donor, collect or remove specific blood components, and return the remaining back to the individual. Apheresis is an integral part of blood and marrow transplantation and has been increasingly utilized in novel cellular therapies for a variety of blood disorders. This review uses clinical cases to highlight the multiple roles of apheresis in the care of adult leukaemia patients, including therapeutic leukapheresis in hyperleukocytosis, mobilized peripheral blood hematopoietic progenitor cell collection in donors, mononucleated cell collection in preparation of donor lymphocyte infusion or chimeric antigen receptor T cells manufacture, and extracorporeal photopheresis in the treatment of graft versus host diseases.

Stem cell mobilization in multiple myeloma: challenges, strategies, and current developments

Among hematological malignancies, multiple myeloma (MM) represents the leading indication of autologous hematopoietic stem cell transplantation (auto-HCT). Auto-HCT is predominantly performed with peripheral blood stem cells (PBSCs), and the mobilization and collection of PBSCs are essential steps for auto-HCT. Despite the improved success of conventional methods with the incorporation of novel agents for PBSC mobilization in MM, mobilization failure is still a concern. The current review comprehensively summarizes various mobilization strategies for mobilizing PBSCs in MM patients and the evolution of these strategies over time. Moreover, existing evidence substantiates that the mobilization regimen used may be an important determinant of graft content. However, limited data are available on the effects of graft characteristics in patient outcomes other than hematopoietic engraftment. In this review, we discussed the effect of graft characteristics on clinical outcomes, mobilization failure, factors predictive of poor mobilization, and potential mobilization regimens for such patients.

Efficacy and safety of a reduced dose of plerixafor in combination with granulocyte colony-stimulating factor in healthy haploidentical stem cell donors

BACKGROUND AND OBJECTIVES

Implementation of the technique of immunomagnetic selection requires the procurement of a large number of CD34+ cells from haploidentical donors within a single apheresis procedure. The release of stem cells with granulocyte colony-stimulating factor (G-CSF) alone is unsatisfactory in a number of donors, and plerixafor, a CXCR4 chemokine receptor antagonist, could be used as an additional mobilization agent. The aim of our study was to examine whether a lower dose of plerixafor (0.12 mg/kg) can provide sufficient increase in CD34+ cells in the peripheral blood of allogeneic healthy donors in comparison with a historical control group. In addition, we assessed the risk of inability to provide the recipient with a transplant containing the optimal dose of 8-10 × 10⁶ CD34+ cells/kg body weight of the recipient.

MATERIALS AND METHODS

In a prospective, single-arm study, we examined the results of 105 mobilizations in healthy adult haploidentical donors with G-CSF and plerixafor at a dose of 0.12 mg/kg. The historical control group consisted of 106 mobilizations with G-CSF and plerixafor at 0.24 mg/kg.

RESULTS

The median increase in the number of CD34+ cells from day 4 to day 5 of mobilization was 69 cells/μl (range, 28-240) versus 77 cells/μl (24-217) in the groups of 0.12 and 0.24 mg/kg of plerixafor, respectively (p-value 0.255). The apheresis products contained a median of 14.4 × 10⁶ /kg recipient body weight CD34+ cells versus 12.9 × 10⁶ /kg in the groups that received 0.12 and 0.24 mg/kg of plerixafor, respectively (p-value 0.118). The obtained differences were not significant, which means the application of a decreased dose of plerixafor did not affect the results of mobilization.

CONCLUSION

The obtained differences in collection were not significant, and thus the application of a decreased dose of plerixafor did not affect the results of mobilization.

Plerixafor use in autologous hematopoietic stem cell mobilization: Experience from a single center in Southern India

BACKGROUND

Plerixafor is used for patients at risk of Stem cell mobilization failure based on clinical factors or low peripheral blood CD34 count. It is also added upfront to any mobilization irrespective of risk factor, but the cost-effectiveness of the approach is an issue. Data on plerixafor in different settings of autologous hematopoietic stem cell (HSC) collection from India are scant. We are hereby reporting the experience of failure/success of mobilization rate and few important significant variables (CD34+ dosage, failed collection) between plerixafor and granulocyte colony-stimulating factor alone groups among autologous hematopoietic stem cell transplantation (aHSCT) at our institute.

METHODS

This was a record-based single-center study on patients who underwent aHSCT from January 2013 to June 2019 at a tertiary care hospital. Descriptive statistics were used for baseline characteristics, transplant-related factors, and peritransplant outcomes. All statistical analyses were performed at the 5% significance level.

RESULTS

During the study duration, a total of 96 patients had undergone autologous hematopoietic stem cell collection (aHSCC), all by peripheral blood stem cell harvest, requiring 131 apheretic collections. Of the total 131 collections in 96 patients, plerixafor was used in 63 apheresis collections (48% of total pheresis) in 40 patients. Among the 40 patients who were administered plerixafor to augment the collection, 34 patients had upfront use of plerixafor. We did not observe any significant adverse event related to plerixafor use.

CONCLUSION

A rational utilization of plerixafor can facilitate the process and logistics of aHSCC outcome.

Use of Plerixafor for Stem Cell Mobilization in the Setting of Autologous and Allogeneic Stem Cell Transplantations: An Update

Mobilization failure is an important issue in stem cell transplantations. Stem cells are yielded from the peripheral blood via apheresis. Granulocyte colony-stimulating factor (G-CSF) is the most commonly used mobilization agent among patients and donors. G-CSF is administered subcutaneously for multiple days. However, patients with mobilization failure cannot receive autologous stem cell transplantation and, therefore, cannot be treated adequately. The incidence rate of mobilization failure among patients is about 6–23%. Plerixafor is a molecule that inhibits the binding of chemokine receptor-4 with stromal-cell-derived factor-1, thereby resulting in the release of CD34+ cells in the peripheral blood. Currently, plerixafor is used in patients with mobilization failure with G-CSF and is administered subcutaneously. Several studies conducted on different clinical settings have shown that plerixafor is effective and well tolerated by patients. However, more studies should be conducted to explore the optimal approach for plerixafor in patients with mobilization failure. The incidence of mobilization failure among donors is lower. However, plerixafor is not approved among donors with mobilization failure. Moreover, several clinical studies in donors have shown a beneficial effect of plerixafor. In addition, the adverse events of plerixafor are mild and transient, which can overcome the adverse events due to G-CSF. This review assessed the current role and effects of plerixafor in stem cell mobilization for autologous and allogeneic stem cell transplantations.

Plerixafor added to G-CSF allows mobilization of a sufficient number of hematopoietic progenitors without impacting the efficacy of TCR-alpha/beta depletion in pediatric haploidentical and genoidentical donors failing to mobilize with G-CSF alone

BACKGROUND

Collection of a large number of early hematopoietic progenitors is essential for allogeneic apheresis products intended for TCR-alpha/beta depletion.

MATERIALS AND METHODS

We added plerixafor 0.24 mg/kg body weight (bw) on day 4 of high-dose filgrastim mobilization 10 hours prior to apheresis in 16 (30.5%) pediatric allogeneic donors who failed to recover a sufficient number of CD34+ cells.

RESULTS

On day 4 of G-CSF, the median CD34+ cell count in peripheral blood was 6 per μL (range 4-9 per μL) in 6 poor mobilizers and 16 per μL (range 12-19 per μL) in insufficient mobilizers. In all donors, the threshold of 50 CD34+ cells/μL was achieved, and the median increase was 14.8-fold in poor mobilizers and 6.5-fold in insufficient mobilizers, whereas it was 3.45-fold increase in those mobilized with G-CSF alone.

DISCUSSION

In all donors, a predefined number of >10 × 10⁶ CD34+ cells/kg of recipient bw before depletion was reached in the apheresis product. The use of plerixafor did not affect the purity of further TCR-alpha/beta depletion. Side effects were mild to moderate and consisted of nausea and vomiting.

CONCLUSION

Thus, the safety and high efficacy of plerixafor was proven in healthy pediatric allogeneic hematopoietic cell donors.

Bone Marrow Transplantation in Patients With Acute Leukemia In Cuba: Results From the Last 30 Years and New Opportunities Through International Collaboration

Blood and marrow transplantation (BMT) has been performed in Cuba for over 30 years with limited resources and without international relationships. Researchers from University of Illinois at Chicago and Hermanos Ameijeiras Hospital (HAH) in Havana collaborated on retrospectively analyzing 101 consecutive patients with adult acute leukemia who received BMT at HAH from June 1986 to January 2016. Of these, 82 had acute myeloid leukemia (AML) and 19 had acute lymphoblastic leukemia (ALL). BMT eligibility criteria included prior morphologic complete remission, no severe comorbidities, and age between 16 and 60 years. Patients with an HLA-matched donor received an allogeneic BMT, whereas the others received an autologous BMT. All patients received fresh stem cells from marrow (80%) or mobilized peripheral blood (19%). Of 82 patients with AML, 35 received an allogeneic (AML-allo) and 47 an autologous (AML-auto) BMT. Both groups had comparable median age (37 years) and follow-up of survivors. Overall survival (OS) was 34% in AML-allo and 38% in AML-auto. The transplant-related mortality rate was 40% in AML-allo and 17% in AML-auto, whereas the relapse-related mortality rates were 25% and 40%, respectively. Of the 19 patients with ALL, six received an allogeneic transplant. Of these, transplant-related mortality occurred in one patient and three died after disease relapse (OS, 33%). Of 13 patients who received autologous transplants, transplant-related mortality occurred in three and six died after disease relapse (OS, 31%). To our knowledge, this is the first scientific report on BMT performed in patients with acute leukemia in Cuba. The collaboration between University of Illinois at Chicago and HAH will further develop capacity building in research and implementation of new diagnostic and therapeutic strategies in Cuba.

Higher CD45RA+ Regulatory T Cells in the Graft Improves Outcome in Younger Patients Undergoing T Cell-Replete Haploidentical Transplantation: Where Donor Age Matters

To understand the phenomenon of early alloreactivity (EA) in younger children undergoing post-transplantation cyclophosphamide (PTCy)-based haploidentical transplantation, we studied the graft composition and the immune reconstitution in 32 consecutive patients (aged 2 to 25 years) undergoing PTCy and T cell costimulation blockade based peripheral blood stem cell transplantation with emphasis on CD45RA⁺ subset of regulatory T cells (Tregs). All but 1 engrafted, and 14 patients experienced EA (acute graft-versus-host disease grades II to IV, n = 8; and post-transplantation hemophagocytic syndrome, n = 6) with a cumulative incidence of 43.7%; 42% developed mild chronic graft-versus-host disease. The overall survival was 70.2% with a nonrelapse mortality of 16.8% at a median of 19 months. Age < 10 years, donor age > 45 years, and poor recovery of Tregs correlated with EA. Not Tregs but higher CD45RA⁺ Tregs in the graft was associated with less EA (11.7% versus 32.5%, P = .0001). Higher donor age correlated with a lower CD45RA⁺ Tregs in the graft (P = .01). However, only higher CD45RA⁺ Treg percentage in the graft favorably impacted EA as well as nonrelapse mortality and overall survival. Our study demonstrates a critical role for CD45RA⁺ Tregs in determining EA and outcome after PTCy-based haploidentical peripheral blood stem cell transplantation, and the age-related physiologic decline in this population might be responsible for adverse impact of donor age.