Leukapheresis products in multiple myeloma: lower tumor load after mobilization with cyclophosphamide plus granulocyte colony-stimulating factor (G-CSF) compared with G-CSF alone

High-dose therapy with autografting of peripheral blood stem cells (PBSCs) has become an accepted treatment modality. However, gene-marking studies in patients with acute myeloid leukemia and neuroblastoma have revealed that malignant cells reinfused along with leukapheresis products (LPs) contribute to relapse. Thus, a reduction in the number of malignant cells in autografts is desirable. We analyzed the percentage of malignant cells and the number of CD34+ PBSCs in LPs mobilized by granulocyte colony-stimulating factor (G-CSF) alone (LP-S) compared with high-dose cyclophosphamide plus G-CSF (LP-CY) in patients with multiple myeloma (MM). A quantitative polymerase chain reaction assay involving CDR3-specific primers based on the method of limiting dilutions was used to determine the tumor loads of LPs. Sixteen LPs from eight patients with MM were analyzed intraindividually in matched pairs. The percentage of malignant cells was lower in LP-CY (p = 0.017; median 0.0067 vs. 0.009%), whereas the number of CD34+ cells was higher (p = 0.012; median 0.3 vs. 0.095%). The calculated number of malignant cells per CD34+ cell was significantly lower in LP-CY as well (p = 0.017). We conclude that mobilization by cyclophosphamide plus G-CSF leads to a lower number of malignant cells per CD34+ cell in LPs compared with G-CSF alone.

First and second apheresis in patients with multiple myeloma: no differences in tumor load and hematopoietic stem cell yield

Autologous peripheral blood stem cells (PBSC) are now widely used to support myeloablative therapy in patients with multiple myeloma (MM). The presence of malignant cells in these autografts has been demonstrated. Characteristic kinetics with differential and concomitant mobilization of CD34+ and malignant cells after high-dose (HD) chemotherapy and hematopoietic growth factor administration have been reported. We determined the amounts of tumor cells and PBSC in leukapheresis products (LP) collected on day 1 (LP1) and 2 (LP2) from 16 MM patients harvested after HD chemotherapy and G-CSF. Furthermore, LP from six patients collected on day 5 (LP5) could be examined. The content of clonotypic cells was quantitated by an allele-specific oligonucleotide (ASO)-PCR assay based on limiting dilutions. CD34+ PBSC were determined by flow cytometry. The percentages of malignant cells in the leukapheresis products were in the range of 0% to 0.713% (mean 0.047%). CD34+ cells ranged between 0.06% and 5.4% (mean 1.23%). Comparing LP1 with LP2, no differences in the quantity of tumor cells (mean 0.0538% vs 0.0448%; P = 0.96) and CD34+ cells (mean 1.49% vs 1.33%; P= 0.50) were seen. The calculated number of tumor cells per CD34+ cell did not differ significantly (mean 0.0420 vs 0.0249; P = 0.65). Analyzing LP5 revealed no changes in the number of tumor cells per CD34+ cell (0.0511 vs 0.1044; P = 0.46) indicating a relatively constant ratio of PBSC to tumor cells during the course of PBSC harvesting. These results offer the possibility of combining LP harvested over several days without increasing the tumor load per CD34+ cell.

Decreased numbers of circulating B cells in myeloma patients with reduction after conventional chemotherapy

Reports of high numbers of circulating monotypic B cells in patients with multiple myeloma (MM) have recently been published. These cells, which were identified by their expression of CD19, were reported to be resistant to conventional chemotherapy and to represent the source of relapse. We examined blood samples from 48 patients before and 53 patients after glucocorticoid containing chemotherapy by dual color flow cytometry. The absolute count of CD19+B cells in patients before treatment (212.6+/-24.8 x 10(6)/l) was decreased compared to normal controls (P = .038). In the post-treatment group, circulating B cells were highly significantly lower than in untreated patients (45.23+/-6.69 x 10(6)/l. P < .001). This reduction was also seen in 26 patients, that were followed during chemotherapy. The cytoplasmic kappa/lambda ratio was within normal range before and after treatment with no difference according to the light chain isotype of the paraprotein. We conclude that circulating B cells are not increased in patients with MM, that the majority of these cells are polyclonal, and that conventional chemotherapy effectively reduces circulating B cells without leading to dominance of resistant monotypic cells.

Increased risk of catheter colonization and catheter-related infections in severe immunocompromized patients with multiple myeloma undergoing high-dose glucocorticoid treatment

Catheter-related infections (CRI) are an important problem in medicine because of major consequences for treatment, prolongation of hospitalization and increasing therapy costs. Malignancies, immunodeficiency, severe burns and malnutrition compromise host defense. Studies to quantify the increased risk of CRI in immunocompromised patients are required. We analyzed the influence of immunoglobulin deficiency and high-dose glucocorticoid treatment in patients with multiple myeloma with regard to catheter colonization and CRI. In patients with multiple myeloma, central venous catheters (CVC) were significantly more frequently colonized (> 15 CFU) as compared to patients with other malignancies undergoing chemotherapy. We found a tendency towards a higher CRI rate in the myeloma patient group. Interestingly, despite of the significantly higher incidence of catheter colonization and a tendency towards higher CRI rates in severely immunocompromised patients, the incidence of signs of local (redness of the entry site) and systemic (fever) host reactions is reduced in myeloma patients. To decrease the CRI rate in myeloma patients during chemotherapy which includes high-dose glucocorticoids, we use antibacterial (silver-coated) catheters.

High-dose chemotherapy in multiple myeloma

The median survival of conventionally treated patients with multiple myeloma is 3 years. Modifications of conventional chemotherapy have failed to show an improved survival rate in most randomized trials. Therapy regimens with dose-escalated alkylating agents (ie melphalan) have induced higher remission rates in comparison to conventional treatment modalities. With the support of autologous or allogeneic hematopoietic progenitor cells, it has been possible to reduce the hematoxicity of these dose-escalated treatments. The transplantation of autologous peripheral blood progenitor cells results in faster hematopoietic reconstitution with decreased high-dose therapy-related morbidity compared to autologous bone marrow. The randomized French myeloma trial and the pair-mate analysis of the results of the 'total therapy' including double autografting of the Barlogie group with data from the South Western Oncology Group (SWOG) showed a significant survival advantage for patients following autologous transplantation. Although a graft-versus-myeloma effect was described, the benefit of high-dose treatment with allogeneic transplantation is less clear, mainly due to the high transplantation-related mortality rate. In this paper, results of transplantation trials are summarized. Prognostic factors and future treatment modalities for myeloma are discussed.

Peripheral blood progenitor cell transplantation in multiple myeloma following high-dose melphalan-based therapy

The objective of our study was to evaluate the efficacy and toxicity of a high-dose melphalan-based therapy with or without total body irradiation (TBI) followed by peripheral blood progenitor cell (PBPC) transplantation in patients with multiple myeloma. Between June 1992 and June 1996, 104 patients (71 male, 33 female) with a median age of 51 years (range 30-65 years) underwent transplantation at our center. PBPC were mobilized using high-dose chemotherapy followed by treatment with G-CSF. Fifty patients were treated with TBI+melphalan 140 mg/m2 while 54 patients received melphalan 200 mg/m2. Following PBPC autografting, the median time to attainment of platelets > or = 20 x 10(9)/l and neutrophils > or = 0.5 x 10(9)/l was 11 and 14 days, with no difference between the treatment groups. In the TBI group significantly longer periods of total parenteral nutrition were required due to the occurrence of severe mucositis. Two patients from the TBI group died of transplantation-related complications. Following high-dose treatment, remission state improved in 43 out of 102 patients. No statistically significant advantage in reaching complete or partial remission was observed with TBI+high-dose melphalan compared to the treatment with high-dose melphalan alone. The optimal high-dose treatment, with particular reference to the inclusion or omission of TBI, should be prospectively investigated.

Factors influencing collection of peripheral blood progenitor cells following high-dose cyclophosphamide and granulocyte colony-stimulating factor in patients with multiple myeloma

We treated 103 multiple myeloma (MM) patients with 7 g/m2 cyclophosphamide (Cy) followed by 300 micrograms G-CSF/d to harvest peripheral blood progenitor cells (PBPC). PBPC autografts containing > 2.0 x 10(6) CD34+ cells per kg body weight were obtained at the first attempt from 90/100 evaluable patients. The most significant factor predicting impairment of PBPC collection was the duration of previous melphalan treatment (P < 0.0001). In multivariate discriminate analysis, treatment with melphalan during the most recent chemotherapy cycles prior to mobilization (P = 0.0727) and previous radiotherapy (P = 0.0628) had a marginally significant negative influence on the efficacy of PBPC collection. We found no reduced functional capacity of CD34+ cells to restore haemopoiesis after myeloablative treatment related to the duration of melphalan exposure. At the time of best response to conventional treatment, a median paraprotein reduction of 21% was achieved following high-dose cyclophosphamide (HD-Cy). Two heavily pretreated patients died and one patient developed pulmonary toxicity W.H.O. grade IV following HD-Cy. Potential transplant candidates should undergo mobilization and harvesting of PBPC before melphalan-containing treatment. Combinations of haemopoietic growth factors and their dose-modifications should be investigated to improve PBPC collection, to allow a dosage reduction of the mobilization chemotherapy.

A quantitative PCR assay for the detection of low amounts of malignant cells in multiple myeloma

BACKGROUND

High-dose chemotherapy (HDT) with autografting of hematopoietic stem cells induces up to 50% of complete remissions in patients with multiple myeloma. Cases of molecular remissions have been reported. However, qualitative assays determine only the absence or presence of a monoclonal population depending on their sensitivity. Therefore reliable and sensitive methods to quantitate tumor loads are necessary.

MATERIALS AND METHODS

We have established a quantitative PCR assay (qPCR) with allele-specific primers complementary to hypervariable CDR3 regions. Sample DNA was serially diluted in 0.5 log steps and amplified in 10 replicates. PCR results were analysed by likelihood maximization and chi 2 minimization to calculate the tumor load.

RESULTS

Three approaches were taken to validate the qPCR. 1) Single copies of the CDR3 region of U266 cells could be detected. 2) Analysis of a bone marrow sample by FACS for CD 38+2 and kappa/lambda restricted plasma cells and by qPCR yielded results of 1.4 and 2.5% respectively. 3) qPCR results with plasmids carrying CDR3 regions simulating different tumor loads diverged by no more than a factor of 1.6 from the expected values.

CONCLUSION

We consider the qPCR to be an accurate method for assessing samples with low amounts of malignant cells.

High-dose therapy with peripheral blood progenitor cell transplantation in multiple myeloma

BACKGROUND

The objective of our study was to evaluate the efficacy and toxicity of a high-dose melphalan-based (HD-Mel) therapy with or without total body irradiation (TBI) followed by peripheral blood progenitor (PBPC1 transplantation in patients with multiple myeloma (MM).

PATIENTS AND METHODS

Between June 1992 and May 1996, 100 patients (67 males 33 females with a median age of 51 years range 30-65) were transplanted at our centre. PBPC were collected during G-CSF-enhanced leukocyte recovery following high-dose chemotherapy. Fifty patients were treated with TBI + melphalan 140 mg m2, while 50 patients received melphalan 200 mg/m2.

RESULTS

Following PBPC autografting, the median time to reach platelets > or = 20 x 10(9) 1 and neutrophils > or = 0.5 x 10(9)/1 was 11 and 14 days with no difference between the treatment groups. In the TBI group significantly longer periods of total parenteral nutrition were required due to severe mucositis. Two patients from the TBI group died due to transplantation-related complications. Following high-dose treatment, remission state improved in 43 out of 98 patients. No statistically significant advantage in reaching CR or PR was observed with TBI + HD-Mel compared to the treatment with HD-Mel alone.

CONCLUSION

Dose-escalated treatments, with particular regard to the inclusion or omission of TBI, should be prospectively investigated to find the best high-dose regimen.

[Malignant lymphoma. Pathology, diagnosis, therapy]

Malignant lymphomas can be subdivided into Hodgkin's disease and low- or high-grade non-Hodgkin's lymphoma (NHL). The principal therapeutic options are polychemotherapy and radiotherapy. Besides the histological classification, staging of the disease with particular regard to risk factors is an essential prerequisite for the therapeutic decision. Diagnostic imaging modalities such as computer tomography, magnetic resonance imaging, and ultrasonography have improved the accuracy of clinical staging such that invasive pathological staging is only necessary in exceptional cases. A novel therapeutic approach is high-dose chemotherapy with autologous haematopoietic stem-cell support. This treatment improves the survival of patients with relapsed high-grade NHL. The place of high-dose therapy as the primary therapeutic option in malignant lymphoma is now being assessed in prospective studies following encouraging results from single-centre studies, including those involving the treatment of low-grade lymphoma. The effects of antibodies directed against lymphatic cells are currently being examined in experimental treatments. An assessment of the viability and rate of proliferation of lymphoma tissue on completion of therapy using sensitive radiological and nuclear medical methods is an important aim for the future.