Plerixafor and autologous stem cell transplantation: impressive result in a chemoresistant testicular cancer patient treated with high-dose chemotherapy. Anticancer Drugs. 2013;24:653-657. [PMID: 23698254 DOI: 10.1097/cad.0b013e328360cd8c]

Hematopoietic stem cell mobilization strategies to support high-dose chemotherapy: A focus on relapsed/refractory germ cell tumors

High-dose chemotherapy (HDCT) with autologous hematopoietic stem cell transplantation has been explored and has played an important role in the management of patients with high-risk germ cell tumors (GCTs) who failed to be cured by conventional chemotherapy. Hematopoietic stem cells (HSCs) collected from the peripheral blood, after appropriate pharmacologic mobilization, have largely replaced bone marrow as the principal source of HSCs in transplants. As it is currently common practice to perform tandem or multiple sequential cycles of HDCT, it is anticipated that collection of large numbers of HSCs from the peripheral blood is a prerequisite for the success of the procedure. Moreover, the CD34+ cell dose/kg of body weight infused after HDCT has proven to be a major determinant of hematopoietic engraftment, with patients who receive > 2 × 10⁶ CD34+ cells/kg having consistent, rapid, and sustained hematopoietic recovery. However, many patients with relapsed/refractory GCTs have been exposed to multiple cycles of myelosuppressive chemotherapy, which compromises the efficacy of HSC mobilization with granulocyte colony-stimulating factor with or without chemotherapy. Therefore, alternative strategies that use novel agents in combination with traditional mobilizing regimens are required. Herein, after an overview of the mechanisms of HSCs mobilization, we review the existing literature regarding studies reporting various HSC mobilization approaches in patients with relapsed/refractory GCTs, and finally report newer experimental mobilization strategies employing novel agents that have been applied in other hematologic or solid malignancies.

Plerixafor-aided Mobilization of Peripheral Blood Hematopoietic Stem Cells to Support Subsequent High-dose Chemotherapy After a Prior Autologous Transplant

BACKGROUND

An appreciable proportion of patients in need of salvage high-dose chemotherapy (HDC) and autologous peripheral blood stem cell (PBSC) transplantation (PBSCT) fail to mobilize adequate numbers of hematopoietic progenitors, and plerixafor is applied for that purpose. Limited data exist on remobilization of PBSCs in patients who have relapsed after prior HDC + PBSCT. Herein, we report on consecutive patients that had undergone successful prior single or tandem HDC for a variety of malignant neoplasms in our institution, and later required re-mobilization of PBSCs in order to support further HDC cycles.

PATIENTS AND METHODS

Plerixafor was administered in combination with granulocyte-colony stimulating factor alone, or after mobilizing chemotherapy. Five patients, 2 B-cell non-Hodgkin lymphomas, 1 multiple myeloma, 1 germ-cell tumor, and 1 Ewing sarcoma, having relapsed after prior HDC + PBSCT, were deemed candidates for further cycle(s) of PBSC-supported HDC. Plerixafor was applied in a "just-in-time" strategy after low CD34+ numbers were measured on the first day of anticipated hematopoietic stem cell collection (non-Hodgkin lymphoma, germ-cell tumor, and Ewing sarcoma), or pre-emptively in multiple myeloma.

RESULTS

Successful collection of adequate PBSCs was achieved in all patients, from 1.8 to 3.8 × 10⁶/kg after a median of 2 (range, 1-3) leukaphereses; 4 of 5 patients underwent subsequent HDC + PBSCT and engrafted after a median of 11 days (range, 9-55 days) and 25 days (range, 17-76 days) for neutrophils and platelets, respectively.

CONCLUSION

Plerixafor proved effective to mobilize adequate numbers of PBSCs in individual patients with relapsed malignancies after prior single or tandem HDC + PBSCT. These PBSCs could establish sustained multi-lineage hematopoietic engraftment without any sequelae.

Plerixafor mobilization of peripheral blood hematopoietic progenitors to support further high-dose chemotherapy cycles in a patient with germ-cell tumor relapsing after previous tandem high-dose chemotherapy and hematopoietic cell transplantation: report of a case

Salvage high-dose chemotherapy (HDC) and autologous hematopoietic stem cell (HSC) transplantation represents a curative treatment option for patients with relapsed/refractory germ-cell tumors (GCTs). However, an appreciable proportion of these fail to mobilize adequate numbers of hematopoietic progenitors; thus, plerixafor is applied for that purpose. Limited data exist on remobilization of HSCs after previous autografting. Here, we report a unique case that had undergone successful previous tandem HDC for relapsed GCT, and 1 year later required remobilization of HSCs to support two further cycles of HDC after subsequent multiple relapses and refractoriness requiring various salvage regimens. Plerixafor in combination with granulocyte-colony stimulating factor showed its efficacy in mobilizing 6×10 CD34+/kg HSCs able to rescue two HDC cycles of carboplatin-etoposide, leading to stable hematopoietic engraftment. Plerixafor showed its potency to mobilize adequate numbers of HSCs in a patient with relapsed/refractory GCT after previous tandem HDC and autografting. The case is discussed in the context of HSC mobilization in patients who have undergone previous HDC and autografting and are deemed to have poor hematopoietic reserves, and a detailed literature review of this topic is provided.

High dose chemotherapy with stem cell support in the treatment of testicular cancer

Testicular germ cell cancer (TGCC) is rare form of malignant disease that occurs mostly in young man between age 15 and 40. The worldwide incidence of TGCC is 1.5 per 100000 man with the highest rates in North Europe. After discovery of cisplatin cure rates of TGCC are very favorable between 90%-95% and unlike most solid tumors, cure rate for metastatic TGCC is around 80%. Metastatic TGCC is usually treated with 3-4 cycles of bleomycin, etoposide, cisplatinum chemotherapy with or without retroperitoneal surgery and cure rates with this approach are between 41% in poor risk group and 92% in good risk group of patients. Cure rates are lower in relapsed and refractory patients and many of them will die from the disease if not cured with first line chemotherapy. High dose chemotherapy (HDCT) approach was used for the first time during the 1980s. Progress in hematology allowed the possibility to keep autologous haematopoietic stem cells alive ex-vivo at very low temperatures and use them to repopulate the bone marrow after sub-lethal dose of intesive myeloablative chemotherapy. Despite the fact that there is no positive randomized study to prove HDCT concept, cure rates in relapsed TGCC are higher after high dose therapy then in historical controls in studies with conventional treatment. Here we review clinical studies in HDCT for TGCC, possibilities of mobilising sufficient number of stem cells and future directions in the treatment of this disease.

Cytokine networking of innate immunity cells: a potential target of therapy

Innate immune cells, particularly macrophages and epithelial cells, play a key role in multiple layers of immune responses. Alarmins and pro-inflammatory cytokines from the IL (interleukin)-1 and TNF (tumour necrosis factor) families initiate the cascade of events by inducing chemokine release from bystander cells and by the up-regulation of adhesion molecules required for transendothelial trafficking of immune cells. Furthermore, innate cytokines produced by dendritic cells, macrophages, epithelial cells and innate lymphoid cells seem to play a critical role in polarization of helper T-cell cytokine profiles into specific subsets of Th1/Th2/Th17 effector cells or regulatory T-cells. Lastly, the innate immune system down-regulates effector mechanisms and restores homoeostasis in injured tissue via cytokines from the IL-10 and TGF (transforming growth factor) families mainly released from macrophages, preferentially the M2 subset, which have a capacity to induce regulatory T-cells, inhibit the production of pro-inflammatory cytokines and induce healing of the tissue by regulating extracellular matrix protein deposition and angiogenesis. Cytokines produced by innate immune cells represent an attractive target for therapeutic intervention, and multiple molecules are currently being tested clinically in patients with inflammatory bowel disease, rheumatoid arthritis, systemic diseases, autoinflammatory syndromes, fibrosing processes or malignancies. In addition to the already widely used blockers of TNFα and the tested inhibitors of IL-1 and IL-6, multiple therapeutic molecules are currently in clinical trials targeting TNF-related molecules [APRIL (a proliferation-inducing ligand) and BAFF (B-cell-activating factor belonging to the TNF family)], chemokine receptors, IL-17, TGFβ and other cytokines.