The timing of plerixafor addition to G-Csf and chemotherapy affects immunological recovery after autologous stem cell transplant in multiple myeloma

Optimizing leukapheresis product yield and purity for blood cell-based gene and immune effector cell therapy

PURPOSE OF REVIEW

A critical common step for blood-based ex-vivo gene and immune effector cell (IEC) therapies is the collection of target cells for further processing and manufacturing, often accomplished through a leukapheresis procedure to collect mononuclear cells (MNCs). The purpose of this review is to describe strategies to optimize the apheresis product cell yield and purity for gene and IEC therapies. Relevant data from the conventional bone marrow transplant literature is described where applicable.

RECENT FINDINGS

Product yield is affected by three main factors: the peripheral blood concentration of the target cell, optimized by mobilizing agents, donor interventions or donor selection; the volume of peripheral blood processed, tailored to the desired product yield using prediction algorithms; and target cell collection efficiency, optimized by a variety of device and donor-specific considerations. Factors affecting product purity include characteristics of the donor, mobilizing agent, device, and device settings.

SUMMARY

Strategies to optimize product yield and purity for gene and IEC therapies are important to consider because of loss of target cell numbers or function with downstream steps and detrimental effects of nontarget cells on further manufacturing and patient outcome.

Plerixafor combined with G-CSF for stem cell mobilization in children qualified for autologous transplantation- single center experience

Failure of autologous peripheral blood CD34⁺ stem cells collection can adversely affect the treatment modality for patients with hematological and nonhematological malignant diseases where high dose chemotherapy followed by hematopoietic stem cell transplantation has become part of their treatment. Plerixafor in conjunction with G-CSF is approved for clinical use as a mobilization agent. The clinical efficacy of Plerixafor in CD34⁺ cells collection was analyzed in our institution. A total of 13 patients aged 1-15,5 years received Plerixafor in combination with G-CSF: 7 with neuroblastoma, 2 with Ewing's sarcoma and single patients with Hodgkin's lymphoma, germ cell tumor, retinoblastoma and Wilms tumor. Twelve patients (923%) achieved CD34+ cell counts of ≥ 20 × 10⁶/L after 1-7 doses of Plerixafor. The average 9,9 - fold increase in number of CD34⁺ cells were achieved following the first dose and 429 - fold after second dose of plerixafor. Among the 13 patients, 12 yielded the minimum required cell collection of 2 × 10⁶/kg within an average of 2 doses of Plerixafor. The mean number of apheresis days was 1.75. The median total number of collected CD34⁺ cells was 982 × 10⁶/kg. Plerixafor enables rapid and effective mobilization, and collection of sufficient number of CD34⁺ cells.

Addition of plerixafor to G-CSF in poor mobilizing healthy related donors overcame mobilization failure: An observational case series on behalf of the Grupo Español de Trasplante Hematopoyético (GETH)

Plerixafor (Mozobil, Sanofi) is approved for using in patients with lymphoma and multiple myeloma when steady-state mobilization strategies fail. Although off-label use of plerixafor in healthy related donors (HRD) is known, limited data are available and no recommendations exist to guide its use in this setting. With the aim of collecting data from HRDs who received plerixafor in our country, we designed an observational case series study within the Spanish Group of Hematopoietic Transplant and Cell Therapy (GETH). Plerixafor was administered subcutaneously to 30 HRDs at a median dose of 0.24 mg/Kg (interquartile range (IQR): 0.23-0.25) because mobilization failure after using mobilization with G-CSF (mobilization failure was defined as collection of <4.0 × 10⁶ CD34+ cells/Kg recipient). All HRDs received G-CSF at a median dose of 11 μg/Kg/day (IQR: 10-12) for 4-5 days. Leukocytapheresis after G-CSF mobilization was performed in 23 (77 %) HRDs collecting a median of 1.6 × 10⁶ CD34+ cells/Kg recipient weight (IQR: 0.9-2.5). Addition of plerixafor allowed the collection of a higher median number of CD34 cells (4.98 × 10⁶ CD34+ cells/Kg recipient weight (IQR: 3.5-5.8)) when compared with the collection of CD34+ cells with G-CSF alone (p < 0.01). The final median total number of CD34+ cells collected was 6.1 × 10⁶/Kg recipient weight (IQR: 4.8-7.3). Mild adverse events related with plerixafor administration were reported in 8 (27 %) donors. In conclusion, addition of plerixafor after G-CSF mobilization failure in HRDs allowed collecting higher number of CD34+ cells in comparison with steady-state mobilization.