Immunological reconstitution after high-dose chemotherapy and autologous blood stem cell transplantation for advanced ovarian cancer

Five-year Experience in PBSC Collection: Results of the Catholic University of Rome

Several authors have reported a faster immunological and hemopoietic post- transplant reconstitution using autologous peripheral blood stem cell (PBSC) than using autologous bone marrow stem cells. A large number of PBSC can be collected by leukapheresis during the hematological recovery after induction or salvage chemotherapy. In our experience we demonstrated that several separators, even if they have different results in mononuclear cell (MNC) yields, red blood cell and platelet contaminations, are able to collect PBSC for autotransplantation in patients with several malignant diseases and different status of disease. Eighty three patients were submitted to 590 leukapheresis procedures using 4 different blood cell separators: the results showed that all employed protocols are efficient in the collection of peripheral MNC even if after the widespread use of granulocytecolony stimulating factor (G-CSF) in the harvesting phase, the blood cell separator efficiency in terms of MNC is reduced. The use of GCSF in combination with other growth factors, during chemotherapy mobilization could simplify, in the future, this therapeutical program even if improvements in the efficiency of PBSC collection protocols are required.

Corneal epithelial stem cell delivery using cell sheet engineering: not lost in transplantation

Cell-based therapies have now generated significant interest as novel drug delivery systems, with various adult cell types used in treating a wide range of diseases. To overcome the limits that restrict treatments for corneal surface dysfunction, corneal epithelial stem cells expanded ex vivo have been applied as an alternative approach. While previous studies used various carrier substrates, we present a novel method using cell sheet engineering with temperature-responsive culture dishes to create carrier-free corneal epithelial stem cell sheets that can be transplanted without sutures. Results from clinical trials reveal successful transplantation with the recovery of lost visual acuity in all cases. Cell sheet engineering, therefore, presents a novel method for the delivery of corneal epithelial stem cells, and can also be applied for other approaches of cellular therapeutics.

Metabolism and transport of oxazaphosphorines and the clinical implications

The oxazaphosphorines including cyclophosphamide (CPA), ifosfamide (IFO), and trofosfamide represent an important group of therapeutic agents due to their substantial antitumor and immuno-modulating activity. CPA is widely used as an anticancer drug, an immunosuppressant, and for the mobilization of hematopoetic progenitor cells from the bone marrow into peripheral blood prior to bone marrow transplantation for aplastic anemia, leukemia, and other malignancies. New oxazaphosphorines derivatives have been developed in an attempt to improve selectivity and response with reduced toxicity. These derivatives include mafosfamide (NSC 345842), glufosfamide (D19575, beta-D-glucosylisophosphoramide mustard), NSC 612567 (aldophosphamide perhydrothiazine), and NSC 613060 (aldophosphamide thiazolidine). This review highlights the metabolism and transport of these oxazaphosphorines (mainly CPA and IFO, as these two oxazaphosphorine drugs are the most widely used alkylating agents) and the clinical implications. Both CPA and IFO are prodrugs that require activation by hepatic cytochrome P450 (CYP)-catalyzed 4-hydroxylation, yielding cytotoxic nitrogen mustards capable of reacting with DNA molecules to form crosslinks and lead to cell apoptosis and/or necrosis. Such prodrug activation can be enhanced within tumor cells by the CYP-based gene directed-enzyme prodrug therapy (GDEPT) approach. However, those newly synthesized oxazaphosphorine derivatives such as glufosfamide, NSC 612567 and NSC 613060, do not need hepatic activation. They are activated through other enzymatic and/or non-enzymatic pathways. For example, both NSC 612567 and NSC 613060 can be activated by plain phosphodiesterase (PDEs) in plasma and other tissues or by the high-affinity nuclear 3'-5' exonucleases associated with DNA polymerases, such as DNA polymerases and epsilon. The alternative CYP-catalyzed inactivation pathway by N-dechloroethylation generates the neurotoxic and nephrotoxic byproduct chloroacetaldehyde (CAA). Various aldehyde dehydrogenases (ALDHs) and glutathione S-transferases (GSTs) are involved in the detoxification of oxazaphosphorine metabolites. The metabolism of oxazaphosphorines is auto-inducible, with the activation of the orphan nuclear receptor pregnane X receptor (PXR) being the major mechanism. Oxazaphosphorine metabolism is affected by a number of factors associated with the drugs (e.g., dosage, route of administration, chirality, and drug combination) and patients (e.g., age, gender, renal and hepatic function). Several drug transporters, such as breast cancer resistance protein (BCRP), multidrug resistance associated proteins (MRP1, MRP2, and MRP4) are involved in the active uptake and efflux of parental oxazaphosphorines, their cytotoxic mustards and conjugates in hepatocytes and tumor cells. Oxazaphosphorine metabolism and transport have a major impact on pharmacokinetic variability, pharmacokinetic-pharmacodynamic relationship, toxicity, resistance, and drug interactions since the drug-metabolizing enzymes and drug transporters involved are key determinants of the pharmacokinetics and pharmacodynamics of oxazaphosphorines. A better understanding of the factors that affect the metabolism and transport of oxazaphosphorines is important for their optional use in cancer chemotherapy.

Administration of low-dose interleukin-2 plus G-CSF/EPO early after autologous PBSC transplantation: effects on immune recovery and NK activity in a prospective study in women with breast and ovarian cancer

This study evaluated the effects of low-dose IL-2 plus G-CSF/EPO on post-PBSC transplantation (PBSCT) immune-hematopoietic reconstitution and NK activity in patients with breast (BrCa) and ovarian cancer (OvCa). To this end, two consecutive series of patients were prospectively assigned to distinct post-PBSCT cytokine regimens (from day +1 to day +12) which consisted of G-CSF (5 microg/kg/day) plus EPO (150 IU/kg/every other day) in 17 patients (13 BrCa and 4 OvCa) or G-CSF/EPO plus IL-2 (2 x 10(5) IU/m(2)/day) in 15 patients (10 BrCa and 5 OvCa). Hematopoietic recovery and post-transplantation clinical courses were comparable in G-CSF/EPO- and in G-CSF/EPO plus IL-2-treated patients, without significant side-effects attributable to IL-2 administration. In the early and late post-transplant period a significantly higher PMN count was observed in G-CSF/EPO plus IL-2-treated patients (P = 0.034 and P = 0.040 on day +20 and +100, respectively). No significant differences were found between the two groups of patients in the kinetics of most lymphocyte subsets except naive CD45RA(+) T cells which had a delayed recovery in G-CSF/EPO plus IL-2 patients (P = 0.021 on day +100). No significant difference was observed between NK activity in the two different groups, albeit a significantly higher NK count was observed in G-CSF/EPO plus IL-2 series on day +20 (P = 0.020). These results demonstrate that low-dose IL-2 can be safely administered in combination with G-CSF/EPO early after PBSCT and that it exerts favorable effects on post-PBSCT myeloid reconstitution, but not on immune recovery.

The role of growth factor administration and T-cell recovery after peripheral blood progenitor cell transplantation in the treatment of solid tumors: results from a randomized comparison of G-CSF and GM-CSF

BACKGROUND

Peripheral blood progenitor cell (PBPC) transplantation (PBPCT) combined with post-PBPCT administration of myelopoietic growth factors is a valid therapeutic intervention to rapidly restore hematopoiesis after the delivery of intensive, myeloablative cancer chemotherapy. On the other hand, the best growth factor regimen to potentiate PBPC-mediated immunohematopoietic recovery has yet to be determined.

STUDY DESIGN AND METHODS

In a randomized evaluation, the effects produced by post-PBPCT G-CSF and GM-CSF on myeloid/lymphoid recovery and transplant outcome in women with chemosensitive cancer were compared. Thirty-seven ovarian cancer patients and 34 breast cancer patients ranging in age from 24 to 60 years were treated with carboplatin, etoposide, and melphalan (CEM) high-dose chemotherapy and then randomly assigned to receive G-CSF (5 microg/kg subcutaneously) or GM-CSF (5 microg/kg subcutaneously) until Day 13 after PBPCT. Patients were compared in regard to hematopoietic recovery, posttransplant clinical management, and immune recovery. Finally, clinical outcome was estimated as time to progression and overall survival.

RESULTS

Hematopoietic recovery and posttransplant clinical management were comparable in both the G-CSF and GM-CSF series. Conversely, significantly higher T-cell counts were observed in G-CSF-treated patients during the early and late posttransplant follow-up. Patients who received G-CSF showed a significantly longer median time to progression. A parallel analysis revealed that patients in whom a higher CD3+ count was recovered had a significantly longer overall survival and time to progression.

CONCLUSION

The enhancement of post-PBPCT T-cell recovery observed in G-CSF-treated patients encourages the use of G-CSF to ameliorate immune recovery, which seems to play a role in post-PBPCT control of disease in cancer patients. GM-CSF might be administered to prolong immunosuppression after autologous PBPCT for autoimmune diseases or allogeneic PBPCT.

Activation-induced T cell apoptosis by monocytes from stem cell products

We recently found that mobilized peripheral blood stem cell (PSC) products (from both cancer patients and normal donors) contain high levels of CD14+ monocytes, which can inhibit the proliferation of allogeneic and autologous T cells. We found in our studies that using CD14+ monocytes from mobilized PSC products (from normal and cancer patient donors), normal apheresis products or normal peripheral blood (PB) can affect lymphocyte function and apoptosis-dependent T cell activation. However, it appears that the apoptosis is dependent on the frequency of monocytes, which is increased by both mobilization and apheresis. Both phytohemagglutinin (PHA)- and interleukin (IL)-2-induced proliferation of steady-state peripheral blood mononuclear cells (PBMC) were markedly inhibited by co-culture with irradiated CD14+ monocytes, although inhibition was significantly greater with PHA than with IL-2 stimulation. IL-2 (predominately CD56+ NK cells) or anti-CD3 monoclonal antibody (mAb) and IL-2-expanded lymphocytes (activated T cells) were inhibited by PSC monocytes to a significantly greater level as compared to steady-state lymphocytes. Indeed, no inhibition of T cell proliferation was observed when lymphocytes were co-cultured in the absence of mitogenic or IL-2 stimulation. In contrast, an increased proliferation was observed in co-cultures of CD14+ monocytes and steady-state or activated lymphocytes without mitogenic stimulation. Cell cycle analysis by flow cytometry revealed a significant increase in hypodiploid DNA, in a time-dependent manner, following co-culture of monocytes and PBMC in PHA, suggesting that T cell apoptosis occurred during PHA-induced activation. These results demonstrate that PSC-derived monocytes inhibit T cell proliferation by inducing the apoptosis of activated T cells and NK cells, but not steady-state cells. This suggests a potential role for monocytes in the induction of peripheral tolerance following stem cell transplantation.

High-dose chemotherapy as a consolidation approach in advanced ovarian cancer: long-term results

The aim of this study was to assess the long-term impact of high-dose chemotherapy (HDC) as consolidation in a large series (n = 55) of advanced chemosensitive ovarian cancer patients who were optimally cytoreduced at time of first surgery or at interval debulking surgery (IDS). HDC consisted of carboplatin (600 mg/m(2) days 1 and 2), etoposide (450 mg/m(2) days 1 and 2) and melphalan (50 mg/m(2), days 3 and 4). The primary endpoint of the study was the assessment of time to progression (TTP) and overall survival (OS). In September 2000 the overall population had a median follow-up of 55 months (range 17--137) and a TTP of 35 months with a 5-year TTP rate of 35% (CI 95%: 21--49) whereas OS averaged 75 months with a 5-year OS of 59% (CI 95%: 45--73). In patients achieving optimal primary cytoreduction the median TTP was 44 months with a 5-year rate of 43% (CI 95%: 26--60). In the same series the 5-year OS rate was 62% (CI 95%: 45--79) (median OS = 75 months). In patients who were optimally cytoreduced at the time of IDS the median TTP was 25 months and the 5-year TTP rate was 22% (CI 95%: 3--41) and median OS was 46 months with a 5-year OS rate of 50% (CI 95%: 27--73). HDC with hematopoietic support could represent an effective approach for the treatment of advanced optimally cytoreduced ovarian cancer patients with chemosensitive disease. Patients who underwent IDS because of unresectable tumors at the time of first surgery had the greater survival benefit from HDC.

Mechanisms of immune dysfunction in stem cell transplantation

High dose therapy (HDT) and stem cell transplantation (SCT) results in alterations in the immunologic network, thymic re-education and the induction of peripheral tolerance. The changes to the immunoregulatory cascade and tolerance induction associated with autotransplants have been investigated in a series of studies focused on leukocyte reconstitution and function following HDT and autologous SCT. In these studies, we observed a significant decrease in the CD4:CD8 T cell ratio post-transplantation compared to normal peripheral blood (PB) donors due to a decrease in CD4+ cells. In addition, T cell function (phytohemagglutinin (PHA) mitogenesis) was consistently depressed compared to samples obtained from normal PB donors. The loss of T cell function was associated with an increased frequency of circulating monocytes, their expression of Fas ligand (FasL) and a high frequency of apoptotic CD4+ T cells. Indeed, 28-51% of circulating CD4+ T cells were observed to be apoptotic during the first 100 days following HDT and SCT. These studies suggest that 'primed' or activated Fas+ CD4+ lymphocytes interact with FasL+ monocytes, resulting in apoptosis, leading to the preferential deletion of CD4+ T cells, a decrease in the CD4:CD8 T cell ratio and depressed T cell function. Further, as discussed herein, the T cells are activated with a predominantly type 2 phenotype, which may also contribute to the maintenance of the immunosuppressive condition. Therefore, there is the potential to regulate immune recovery by stem cell product manipulation or post-transplantation cytokine administration.

Reconstitution of the cellular immune response after autologous peripheral blood stem cell transplantation in patients with non-Hodgkin's lymphoma

Peripheral blood stem cell (PBSC) transplants may be depleted of lymphoid progenitors, thereby disabling the cellular immune response against viral pathogens after autologous PBSC transplantation (PBSCT). To monitor the cellular immune reconstitution after autologous PBSCT, we investigated the cytolytic activity (CLA) of peripheral blood T lymphocytes against Epstein-Barr virus (EBV) in 13 patients with non-Hodgkin's lymphoma or multiple myeloma. The individual EBV-directed CLA (EBV-CLA) was determined by calculating the number of cytolytic effector cells in 106 T cells needed to lyse 25% of autologous EBV-transformed B-lymphoblastoid cells, expressed as lytic units (LU25). During the first 6 months after PBSCT, the EBV-CLA was only 14.6% of the response of healthy controls (median 4. 8 vs. 32.9 LU25). Thereafter, the EBV-CLA increased to 28.15 LU25 (median) or 86% of healthy controls. Monthly follow-up analyses in five selected patients showed that the EBV-CLA was barely detectable at 4 weeks and recovered at 8-12 weeks after PBSCT in four out of five patients. Effector cells consisted mostly of CD8-positive T lymphocytes, with small CD4- and CD3/CD56-positive lymphocyte fractions. These results suggest that the reconstitution of the cellular immune response against EBV takes 8-12 weeks after autologous PBSCT.

Usefulness of lymphokine-activated killer cells generated from bone marrow mononuclear cells for the purging of residual tumor cells in peripheral blood stem cell graft

Lymphokine-activated killer (LAK) cells were generated from bone marrow mononuclear cells (BM), and the usefulness of the BM-LAK for purging of residual tumor cells in autologous peripheral blood stem cell (PBSC) graft was determined. The BM and peripheral blood lymphocytes (PBL) were obtained from the same bone marrow donors. The BM-LAK and PBL-LAK were generated by incubation with interleukin-2 for 7 days. The BM-LAK demonstrated higher killer activity against a lymphoma cell line Raji than the PBL-LAK. The BM-LAK also had a higher percentage of CD4-CD8-CD16+ cells than the PBL-LAK, which suggests that their high killer activity is related to these cells. The BM-LAK did not show any killer activity against the PBSC graft. However, they killed tumor cells which contaminated the PBSC graft, and in particular, killed chimeric bcr/abl messenger RNA-positive residual leukemic cells. These results suggest that the BM-LAK may be applicable for purging. As the BM-LAK possess higher killer activity than the PBL-LAK, they may be more useful than the PBL-LAK.

Do autologous peripheral blood cell transplants provide more than hematopoietic recovery?

Bone marrow damage caused by myeloablative radiation therapy and/or chemotherapy can be repaired by intravenously infusing viable stem/progenitor cells collected from either blood or bone marrow. The hematopoietic graft product contains both stem/progenitor cells and populations of hematopoietic and nonhematopoietic (accessory) cells. The frequency of accessory cell types varies with the source of the graft product; marrow or blood. Reinfusion of these accessory cells causes effects other than the hematopoietic restoration provided by the stem/progenitor cells such as graft versus host disease and graft versus leukemia effect after allogeneic transplants. Effects of infused accessory cells in the autologous setting are less well studied and could provide ancillary advantages and/or disadvantages to the patient. Do these additional effects actually occur, and, if they do, are they more likely to appear following peripheral blood cell transplants (PBCT) or after autologous bone marrow transplants (AMBT)? Preliminary data are beginning to accumulate which suggest that reinfusion of occult tumor cells is less likely with PBCT, that immune reconstitution is different depending on the source of the autograft and that, for certain diseases, patient event-free survival following PBCT rather than ABMT may be better. However, infusion of occult tumor cells may result in re-establishment of the malignancy. If the accessory cells (including potential occult tumor cells) are eliminated from the product before transplant, will the patient have a better clinical outcome, or would benefits provided by infused accessory cells outweigh the risks of infused occult tumor cells? These controversial issues are in the very early stages of investigation.

High-dose chemotherapy for breast cancer: clinical advantages of autologous peripheral blood progenitor cells (PBPC) compared with autologous bone marrow transplantation (ABMT)

Peripheral blood progenitor cell (PBPC) autografts have a number of advantages over autologous bone marrow transplantation (ABMT) as haematopoietic support after high-dose chemotherapy in patients with breast cancer. These may include less contamination by tumour cells, reduced morbidity and mortality and additional dose escalation of chemotherapy. A dose-escalation study is described using recombinant granulocyte colony-stimulating factor (G-CSF; filgrastim) primed PBPC support and post-infusion filgrastim for patients with high-risk or metastatic breast cancer. The regimen involved the use of cyclophosphamide, thiotepa and carboplatin at five dose levels. The main problem to emerge was organ toxicity induced by chemotherapy or sepsis. Patients receiving higher levels of chemotherapy were therefore allocated or not to an additional regimen involving pentoxifylline, ciprofloxacin and dexamethasone in an attempt to inhibit tumour necrosis factor alpha (TNF-alpha) which is believed to be one of the principal mediators of chemotherapy-related organ toxicity. The incidence of bilirubin elevations, weight gain > 5% and veno-occlusive disease (VOD) was lower in patients receiving the 'anti-TNF' therapy. The simultaneous use of PBPC support and 'anti-TNF' therapy therefore allows a substantial increase in chemotherapy dosage. Further studies with larger patient numbers are required to show whether this decreased toxicity also produces increased patient survival.