Reduced‐dose plerixafor as a mobilization strategy in autologous hematopoietic cell transplantation: a proof of concept study

Lactate dehydrogenase as a hematopoietic stem cell mobilization biomarker in autologous transplantation

INTRODUCTION

Pre-apheresis peripheral blood CD34+ cell count (PBCD34+) is the most important predictor of good cell mobilization before hematopoietic stem cell transplantation, albeit flow cytometry is not always immediately available. Identification of surrogate markers can be useful. The CD34+ cells proliferate after mobilization, resulting in elevated lactate dehydrogenase (LDH) activity and correlating with the PBCD34+ count.

OBJECTIVE

To determine the LDH cut-off value at which adequate CD34+ cell mobilization is achieved and its diagnostic yield.

MATERIALS AND METHODS

A total of 103 patients who received an autologous stem cell transplantation (ASCT) between January 2015 and January 2020 were included. Demographic and laboratory characteristics were obtained, including complete blood count, pre-apheresis PBCD34+ and LDH levels. Receiver operating characteristic (ROC) curves were performed to identify the optimal serum LDH activity cut-off points for ≥ 2 and ≥ 4 × 106 cells/kg post-mobilization CD34+ count and their diagnostic yield.

RESULTS

A post-mobilization serum LDH cut-off value of 462 U/L yielded a sensitivity (Se) = 86.8% (positive predictive value [PPV] = 72.7%), a pre- and post-mobilization serum LDH difference cut-off value of 387 U/L, an Se = 45.7% (PPV = 97%) and an LDH ratio of 2.46, with an Se = 47.1% (PPV = 97%) for an optimal mobilization count (CD34+ ≥ 4 × 106).

CONCLUSION

The LDH measurement represents a fast and affordable way to predict PBCD34+ mobilization in cases where flow cytometry is not immediately available. According to the LDH diagnostic yield, it could be used as a surrogate marker in transplant centers, supporting the CD34+ count, which remains the gold standard.

Conducting hematopoietic stem cell transplantation in low and middle income countries

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) is a well-recognized therapeutic procedure; costs limit its widespread use in low and middle income countries (LMIC).

METHODS

Over a 30-year period, we have conducted HSCT in LMIC, making adaptations to the conventional procedures conducted in high-income countries (HIC).

RESULTS

These salient observations stem from our practice: (1) Start with autologous transplantations in patients with hematological malignancies, specifically multiple myeloma; cell freezing devices are not necessary. (2) Next, consider auto-HSCT in patients with autoimmune diseases. (3) Introduce allogeneic transplants, initially using reduced intensity conditioning regimens. Conducting the HSCT on an outpatient basis is cheaper and safer. (4) Do not build HEPA-filtered rooms nor laminar flow cabins. (5) Do not graft cord blood cells nor start a cord blood blank. (6) Engage in haploidentical transplantations which are more feasible and cost-effective. (7) Matched unrelated donors are extremely expensive. (8) Use generic drugs and biosimilars. (9) Blood product irradiation devices are not necessary. (10) Do not try to reproduce other HSCT programs from HIC; develop your own methods.

CONCLUSIONS

HSCT can be conducted in LMIC with reduced costs and similar efficacy, thus making this therapeutic option affordable for more persons.

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.

Lessons Learned Treating Patients with Multiple Myeloma in Resource-Constrained Settings

PURPOSE OF REVIEW

Based on personal experiences, recommendations for physicians treating patients with multiple myeloma (MM) in low- and middle-income countries (LMICs) are proposed.

RECOMMENDATIONS

(1) Implement strategies to keep the patient in the best possible condition for the longest time, in addition to focusing on ways to avoid financial toxicity; (2) if lenalidomide is unavailable, start treatment with thalidomide and dexamethasone, include, if possible, bortezomib; (3) conduct an outpatient-based autologous stem cell transplantation (ASCT) in all eligible patients; (4) use thalidomide as post-ASCT maintenance treatment if lenalidomide is unavailable for the standard risk patients; (5) monitor monoclonal proteins with serum protein electrophoresis and free light chain measurements; (6) employ novel drugs in cases of relapsed or refractory disease; and (7) do not forget supportive therapy. The therapeutic recommendations to treat patients with MM are somewhat different for physicians working in LMICs, compared with those treating patients in high-income countries. These are relevant since more than 50% of the inhabitants of the world live in LMICs, thus indicating that the vast majority of patients with MM are being treated in resource-constrained settings. As time goes by, physicians may acquire the ability to analyze and express their feelings and experiences about topics in the practice of medicine in which they could have learned lessons (1). Since 1980, we have been treating patients with multiple myeloma (MM); to date, we have been personally involved in the study and treatment of more than 300 patients with this disease (2). Having gained experience dealing with MM patients in underprivileged circumstances, such as those prevailing in our country: México, having explored different ideas, treatments, and methods, and being aware of the financial implications which may impact our selection of therapeutic strategies and recommendations, we felt that it was appropriate to share in this article some of these ideas with practitioners around the world who are involved in the treatment of patients with MM in low- and middle-income countries (LMICs).