The role of intensive therapy and autologous blood and marrow transplantation for chemotherapy-sensitive relapsed and primary refractory non-Hodgkin's lymphoma: identification of major prognostic groups

Patients with intermediate grade non-Hodgkin's lymphoma (NHL) who relapse or fail to achieve a complete remission after anthracycline-containing induction regimens have a poor outcome with conventional-dose salvage treatment. This outcome may be improved with intensive therapy and autologous transplantation (ABMT) but even in patients with proven chemotherapy-sensitive disease, relapse rates of up to 60% are observed. Reliable and powerful prognostic indicators are needed to identify appropriate patients for this expensive procedure and those subjects to whom alternative or additional treatment should be offered. We were interested in testing the hypothesis that tumour burden, and hence remission status immediately prior to transplant, is an important prognostic indicator of survival. We aggressively treated patients with conventional-dose salvage chemotherapy to maximum tumour response, and tested, by multivariate regression analysis, predictors of outcome post-transplant. We studied 81 consecutive patients with intermediate grade and immunoblastic NHL who achieved either a partial (PR) or complete remission (CR) following repetitive cycles of conventional-dose salvage therapy. Intensive therapy consisted of etoposide (60 mg/kg) and intravenous melphalan (160-180 mg/m2) with or without total body irradiation (TBI) followed by infusion of autologous unpurged bone marrow and/or blood cells. The predicted 4-year survival and progression-free survival (PFS) with a median follow-up of 37 months was 58% and 48% (95% confidence interval (CI) 37-55%), respectively. The only factor predictive of outcome was remission status at transplant (P=0.0001). The PFS at 4 years for the CR group was 61% (95% CI 53-75%). In contrast, only 25% (95% CI 11-40%) of patients undergoing autotransplant in PR were progression free at 4 years. We conclude that remission status at transplant after maximum tumour reduction is a powerful prognostic indicator.

Normal and leukemic SCID-repopulating cells (SRC) coexist in the bone marrow and peripheral blood from CML patients in chronic phase, whereas leukemic SRC are detected in blast crisis

Progress in understanding the abnormal regulation of hematopoiesis in chronic myelogenous leukemia (CML) would be facilitated if neoplastic cells, at all stages of the disease, could be studied in an animal model. In this report, we show that irradiated severe combined immunodeficient (SCID) mice can be transplanted with both normal (Philadelphia chromosome [Ph]-negative) and neoplastic (Ph+) cells from CML patients with either chronic or blast phase disease. Mice transplanted with peripheral blood (PB) or bone marrow (BM) cells from 9 of 12 chronic phase CML patients were well engrafted with human cells including multilineage colony-forming progenitors and CD34+ cells for at least 90 days posttransplantation. Repeated posttransplant injections of cytokines did not enhance the number of engrafted human cells. Interestingly, approximately 70% of the human progenitors found in the engrafted SCID BM were Ph-, suggesting that the growth of primitive normal cells is favored in this in vivo transplant model. A similar number of normal cells were found in mice transplanted with either PB or BM cells, suggesting that elevated numbers of primitive normal cells are present in CML PB. When cells from patients with CML in either myeloid or lymphoid blast crisis were transplanted into SCID mice, the BM of these mice was more rapidly repopulated and to a higher level than that observed with transplants of chronic phase cells. Moreover, all human colony-forming progenitors present in the BM of mice transplanted with blast crisis cells were Ph+, and the majority of cells showed the same morphological features of the blast crisis cells originally transplanted. These experiments provide a starting point for the creation of an animal model of CML and establish the feasibility of using this model for the future characterization of transplantable CML stem cells during disease progression.

Chemotherapy versus transplants for acute myelogenous leukemia in second remission

The best therapy for persons with acute myelogenous leukemia (AML) in 2nd remission is unknown. Bone marrow transplants from an HLA-identical sibling are reported to be better than chemotherapy but this is controversial. The objective of the study was to compare 3-year leukemia-free survival (LFS) in comparable subjects receiving chemotherapy or a transplant. 485 persons with AML in 2nd remission were studied. The chemotherapy cohort included 244 persons treated on trials of the British Medical Research Council, Eastern Cooperative Oncology Group and MD Anderson Hospital. The transplant cohort included 257 persons transplanted worldwide and reported to the international Bone Marrow Transplant Registry (16 were also chemotherapy subjects.) Subjects were selected for comparable age and year of treatment. Preliminary analyses identified two factors correlated with LFS: age < or = or > 30 years and 1st remission duration < or = or > 1 year; subsequent analyses were partitioned accordingly. Three-year probabilities of treatment-related mortality with chemotherapy and transplants were 7% (95% confidence interval, 3-15%) vs 56% (49-63%). Three-year leukemia relapse probabilities were 81% (74-86%) vs 41% (33-49%). Three-year probabilities of LFS were 17% (12-23%) vs 26 (20-32%). Cohort analysis showed significantly higher LFS with transplants vs chemotherapy in persons < or = 30 years and 1st remissions > 1 year (41% (29-53%) vs 17% (7-32%); P = 0.017) and those in > 30 years with 1st remissions < or = 1 year (18% (9-29%) vs 7% (2-16%); P = 0.046). Others had comparable LFS with both treatments. These data indicate better LFS with HLA-identical sibling transplants than chemotherapy in some persons with AML in 2nd remission.

Autologous bone marrow transplantation for acute myeloid leukemia

Despite progress over the past three decades, most patients with acute myeloid leukemia (AML) treated with conventional chemotherapy alone relapse and die of recurrent leukemia. Treatments used to improve outcome include allogeneic (alloBMT) and autologous bone marrow transplantation (ABMT). Indications for transplantation and the relative merits of alloBMT and ABMT remain unclear. In this review, we evaluate evidence supporting a role of ABMT in AML and compare the results with outcomes after alloBMT. In addition, we discuss areas of controversy including the optimal timing for ABMT, the role of bone marrow purging, the place of peripheral blood stem cell collection, the high dose regimen, and post-transplant immunotherapy to reduce relapse.

Biology of bone marrow stroma

The marrow microenvironment is a complex, three-dimensional structure composed of many cell types and abundant extracellular matrix. Much of the data are derived from analysis of the adherent layer of murine and, especially, human long-term marrow cultures. An essential feature of this in vitro counterpart to the marrow microenvironment is the presence of flat angulated cells functionally defined as marrow stromal cells with the following phenotype: type IV collagen(+), laminin(+), vimentin(+), CD10(+), muscle actin(+), Stro-1(+), and negative for CD45, Mac-1, and HLA-DR. Stromal precursors are Stro-1(+) and CD34(+). Regulation of hematopoietic precursors by the microenvironment occurs by elaboration of regulatory molecules such as hematopoietic cytokines, by cell-cell contact via adhesion molecules such as alpha 4 beta 1 integrin, and by interactions with components of the extracellular matrix as in the case of the glycosaminoglycan hyaluronic acid with cell-associated CD44. Although little about the regulation of stromal cell development itself is known, several studies indicate the transplantability of marrow stromal cells under specific conditions. These developments suggest a potential role of stromal cells in cell therapy. Transfected stromal cells may serve as suitable vehicles for gene delivery to correct single gene disorders in which the product of the target gene does not require stringent regulation as, for example, in the correction of Factor VIII and Factor IX deficiency. Further studies are warranted to investigate marrow stromal cell physiology and regulation to better understand hematopoiesis and to explore the possible use of stroma in therapy.

Optimizing the CD34+ and CD34+Thy-1+ stem cell content of peripheral blood collections

We have previously described a sensitive and specific CD34 enumeration assay and report here a prospective analysis of 25 myeloma patients undergoing PBSC mobilization using this assay to determine the optimal days for collection of CD34+ and CD34+Thy-1+ cells after chemotherapy and growth factor mobilization. Correlations between frequency of peripheral blood CD34+ cells, circulating white blood cell (WBC) count, apheresis CD34+ cell count, nucleated cell count (NCC), and numbers of apheresis colony-forming units granulocyte/macrophage (CFU-GM) were determined. To assess levels of the more primitive subsets of CD34+ cells in the PBSC collections, coexpression of the Thy-1 antigen (CDw90) on CD34+ cells was also assessed. Marked heterogeneity was noted between patients with apheresis samples containing a median NCC of 4.2 x 10(8)/kg (range 1.3-8.1), median CFU-GM 17 x 10(4)/kg (range 0.15-32 x 10(4)/kg), and median CD34+ cell count of 1.39 x 10(6)/kg (range 0.02-6.6). The frequency of CD34+ cells in PBSC collections coexpressing Thy-1 was also heterogenous (6.2-50% of CD34+ cells), median 21.6%, mean 24.7 +/- 2%. The apheresis CD34+ cell count correlated with the peripheral blood CD34+ cell percentage (r = 0.71, p < 0.0001) but only weakly with the peripheral WBC. Apheresis CD34+Thy-1+ cell numbers correlated strongly with the circulating CD34+ cell numbers (r = 0.80), but no correlation was noted between these candidate stem cells and the peripheral WBC. In contrast, apheresis CFU-GM levels correlated most strongly with the peripheral WBC count (r = 0.61, p < 0.0001). The apheresis CD34+ cell count correlated with apheresis CFU-GM (r = 0.75, p < 0.0001) but not with the apheresis NCC. Apheresis CD34+Thy-1+ counts significantly correlated only with the apheresis CD34+ cell count and not with the apheresis CFU-GM or NCC. A higher percentage of circulating and apheresis CD34+ cells expressing Thy-1 were found on day 1 of collection, and the percentage of CD34+ cells expressing Thy-1 decreased on each subsequent day of measurement: median of 22% day 1 vs. 16.6% day 4, p = 0.04. This study therefore confirms that accurate quantitation of circulating CD34+ cells best predicts the optimal day for apheresis collection of CD34+ and CD34+Thy-1+ cells and is superior to the WBC count in this regard. Furthermore, the candidate stem cell (CD34+Thy-1+) subset is most prevalent during the earliest phases of CD34+ cell mobilization.

Isolated chloroma: the effect of early antileukemic therapy

OBJECTIVE

To evaluate the effect of antileukemic chemotherapy administered at diagnosis on the survival of patients with isolated chloroma.

DESIGN

Retrospective review of locally identified patients and analysis of cases from the medical literature.

PATIENTS

The records of all patients with isolated chloroma identified at three teaching hospitals in Toronto between 1980 and 1994 were reviewed. A MEDLINE search was done to identify all cases of isolated chloroma reported in the English-language medical literature. Patients with a previous known hematologic disorder were excluded.

MEASUREMENTS

The effect of therapy on 1) the interval between diagnosis of chloroma and diagnosis of acute myeloid leukemia and 2) survival was determined.

RESULTS

7 local patients and 83 published cases were identified, for a total of 90 evaluable patients. For the entire group, the median time to the diagnosis of acute myeloid leukemia was 9 months, and median survival was 22 months. Chemotherapy was administered to 49 patients (54%) at diagnosis of chloroma. Significantly fewer patients treated with chemotherapy subsequently developed acute myeloid leukemia (41% compared with 71%; P = 0.001). Survival was longer in patients treated with chemotherapy (> 50% alive with a median follow-up of 25 months compared with a median survival of 13 months for those initially untreated; P = 0.001). Multivariate analysis showed that neither local radiotherapy nor surgery had an effect on survival.

CONCLUSIONS

Administration of antileukemic chemotherapy at diagnosis of chloroma is associated with a significantly lower probability of developing acute myeloid leukemia and with longer survival.

Severe hepatotoxicity from granulocyte-macrophage colony-stimulating factor administered after autologous bone marrow transplantation

We report a case of life-threatening hepatotoxicity following GM-CSF therapy after autologous bone marrow transplantation. GM-CSF hepatotoxicity should now be considered in the differential diagnosis of post-transplant liver disease.

Acute leukemia in adults

The application of recent discoveries in the field of molecular oncology to acute myeloid and lymphoblastic leukemia has provided new insights into the pathogenesis and natural history of these diseases. Cytogenetic abnormalities and the detection of mutations or abnormal expression of certain oncogenes or tumor suppressor genes now provide powerful prognostic information to guide choice of therapy and prediction of response. Randomized trials of intensive postremission chemotherapy have now confirmed improved leukemia-free survival with the use of high-dose cytarabine or allogeneic or autologous bone marrow transplantation. Progress in the treatment of acute myeloid leukemia and acute lymphocytic leukemia in the elderly, where the prevalence of these diseases is likely to increase as our population ages, has been more modest. There is still a need for the evaluation of new treatment strategies in previously untreated patients with acute leukemia, despite the progress that has been reported during the past year.

Determination of aluminium in serum, dialysate fluid and water by inductively coupled plasma optical emission spectrometry

Methods for the determination of aluminium in serum, dialysate fluid and water by inductively coupled plasma optical emission spectrometry are described and validated. Aluminium was measured at 167 nm using an argon purged monochromator. Matrix effects in serum and dialysate fluid were overcome by using an yttrium internal standard. Serum was found to have a complicated background in the region of 167 nm: careful selection of the wavelength used for background correction is therefore a pre-requisite for accurate analysis. The method for serum was validated by comparison with electrothermal atomization atomic spectrometry and the limit of agreement determined to be +/- 0.3 mumol/L. Routine performance in a quality assessment scheme has been highly satisfactory for a period of 1 year. The method is ideal for fast and accurate monitoring of patients potentially at risk from aluminium toxicity.

Mini-BEAM as salvage therapy for relapsed or refractory Hodgkin's disease before intensive therapy and autologous bone marrow transplantation

PURPOSE

To evaluate the efficacy of carmustine (BCNU), etoposide, cytarabine (Ara-C), and melphalan (mini-BEAM) as salvage therapy in patients with relapsed or refractory Hodgkin's disease who were potentially eligible to undergo intensive therapy and autologous bone marrow transplantation (ABMT).

PATIENTS AND METHODS

Forty-four patients with refractory or relapsed Hodgkin's disease after front-line combination chemotherapy referred for consideration of ABMT were treated with mini-BEAM (BCNU 60 mg/m2 on day 1, etoposide 75 mg/m2 on days 2 to 5, Ara-C 100 mg/m2 twice per day on days 2 to 5, and melphalan 30 mg/m2 on day 6) to maximum response. Eleven patients were refractory to primary chemotherapy. Twenty-three patients were treated in first relapse and 10 in second or subsequent relapse; 21 received mini-BEAM as their first salvage regimen. Patients were restaged to determine disease status immediately before intensive therapy and transplant.

RESULTS

The overall response rate was 84% (exact 95% confidence interval [CI], 70% to 92%), with a complete response (CR) rate of 32% (95% CI, 20% to 47%) and a partial response (PR) rate of 52%. No treatment-related deaths were observed. Myelosuppression was the major toxicity. Almost all patients required platelet transfusions. Eighty-four percent were given RBC transfusions, and 54% required intravenous antibiotics for fever while neutropenic.

CONCLUSION

Mini-BEAM is a safe and effective regimen for treatment of refractory or relapsed Hodgkin's disease. Further studies are required to determine if responding patients have improved disease-free survival (DFS) after intensive therapy and ABMT.

Effect of antimicrobial prophylaxis on hematopoietic recovery following autologous bone marrow transplantation: ciprofloxacin versus co-trimoxazole

We evaluated the effect of oral ciprofloxacin on neutrophil recovery in 20 consecutive patients undergoing autologous bone marrow transplantation (BMT) for malignant lymphoma and compared the results with a control group of 20 patients receiving co-trimoxazole and folinic acid. Both groups started the prophylactic antibiotic as well as granulocyte-macrophage colony-stimulating factor (GM-CSF) the day after marrow infusion and continued the former until the onset of febrile neutropenia (median duration of treatment 6 days for co-trimoxazole and 7 days for ciprofloxacin). The time of attain an absolute neutrophil count > or = 0.5 x 10(9)/L was significantly shorter in patients receiving ciprofloxacin (16 days vs 22 days; P = 0.006). There was no difference in time to attain a platelet count > or = 20 x 10(9)/L independent of transfusion or in time to the first febrile episode or incidence of bacteremia. We conclude that antibiotic prophylaxis with ciprofloxacin results in more rapid neutrophil recovery than prophylaxis with co-trimoxazole. This may result from a myelosuppressive effect of co-trimoxazole or an enhancement of neutrophil recovery by ciprofloxacin, or both.

Outpatient bone marrow harvesting: an update

We previously demonstrated in a pilot study that outpatient marrow harvesting is feasible and safe. Here, we provide an update and analysis of 149 outpatient marrow harvests and compare the results with 61 inpatient harvests. The mean patient age was 33 years. Mean outpatient harvest duration was 41 minutes, similar to inpatients. Average pre- and post-harvest hemoglobin values were 122 and 99 g/L, respectively, for outpatients and 119 and 93 g/L for inpatients. Fifty per cent of patients received an average of two units of homologous packed erythrocytes following the procedure versus 2.3 units for 57% of inpatients. Mean harvest volume was 1248 ml (versus 1341 ml for inpatients) and the mean number of mononucleated cells obtained was 2.73 x 10(8)/kg (3.23 x 10(8)/kg for inpatients). There were no serious complications in patients undergoing out-patient marrow harvesting. Sixteen outpatients (11%) had minor complications of hypotension, fever, nausea, vomiting or moderate pain. Thirteen patients (9%) required subsequent admission for a mean of 1.3 days. Eight inpatients (13%) had similar complications. All patients responded well to fluid replacement and analgesics. We confirm the safety of outpatient marrow harvesting for patients with hematologic malignancies.

Microbial contamination of harvested bone marrow and peripheral blood

The incidence and clinical consequences of microbiological contamination of autologous bone marrow and peripheral blood progenitor cells are not well documented. We therefore retrospectively analysed our experience with bacterial or fungal contamination of harvested bone marrow and/or peripheral blood. From January 1987 to the end of January 1994, 499 patients were harvested or which 301 were transplanted. A total of 3910 specimens obtained during three stages in the processing were assessed for microbial contamination: (1) in the operating room immediately after harvesting (1662 bags) with 2.1% culture positivity, (2) after processing for cryopreservation (1039 bags) with a further 1.1% cultures positive, and (3) after thawing at the time of reinfusion (1209 bags) of which 2.2% were culture positive. There were no culture positive specimens obtained from any peripheral blood progenitor cell products. The vast majority of the 85 culture positive specimens obtained from marrow were skin flora (89%) and 35% of all positive harvest specimens remained positive following processing and freezing. At least 36% of culture positive specimens were thought to have arisen as a result of exogenous contamination of blood culture bottles. Potentially pathogenic enteric organisms were present in nine (0.2%) specimens and infusion of these organisms occurred in four cases. A further seven patients were reinfused with marrow culture positive for skin organisms. No adverse clinical sequelae were noted following infusion of any contaminated products. However, clinical decision making continues to be influenced by culture results and multistage microbial culture continues to be of value in the management of our marrow recipients.

Sensitive detection and enumeration of CD34+ cells in peripheral and cord blood by flow cytometry

Peripheral blood stem cell autografts are increasingly used to reconstitute hematopoiesis after intensive, potentially marrow-ablative therapy. Assessment of autograft adequacy by enumeration of hematopoietic progenitors in colony-forming assays is handicapped by lack of reproducibility and prolonged assay time. Alternative approaches of graft assessment by flow-cytometric enumeration of stem/progenitor cells bearing the CD34 antigen can be hampered by low specificity and sensitivity. Here, we report a rapid and reliable multiparameter flow-cytometric approach to accurately enumerate CD34+ cells in peripheral blood (PB) mononuclear cells (MNCs). Total nucleated white blood cells (WBCs) are quantified by staining with fluorescein isothiocyanate (FITC)-conjugated CD45 antibody. Simultaneous staining by phycoerythrin (PE)-conjugated CD34 antibody defines an approximate number for the CD34+ progenitor/stem cell subfraction. When starting CD34+ cell numbers are low (0.01-0.5%), other nonspecifically stained leukocytes make accurate enumeration impossible. However, when the CD34+ fraction is analyzed for CD45 expression vs. side scatter (granularity), true CD34+ blast cells form a discrete cluster exhibiting low-density CD45 expression and low side-scatter characteristics. Cells within this "blast region" can be readily distinguished from lymphocytes, monocytes, granulocytes, and other events that can contaminate the CD34+ population. Here, we used this sensitive procedure to enumerate CD34+ cells in steady-state PB samples (0.03-0.09%), normal bone marrow (BM) aspirates, and umbilical cord blood collections (0.33-1.98%). This approach thus provides a means to analyze CD34+ cells in specimens from patients who have been extensively treated with chemotherapy and those undergoing PB stem cell mobilization with cytokines. Additionally, it is useful for assessment of CD34+ cells in a variety of clinical samples exhibiting perturbations of the hematopoietic progenitor/stem cell compartments.

Synergistic effect of stem cell factor with interleukin-3 or granulocyte-macrophage colony-stimulating factor on the proliferation of murine primitive hematopoietic progenitors

We examined the effect of recombinant murine stem cell factor (SCF) on murine primitive hematopoietic stem cells in vivo. Marrow cells from 5-fluorouracil (5-FU)-treated male CBA/J mice were transplanted into lethally irradiated female littermates. Immediately after marrow transplant, the mice received SCF, interleukin-3 (IL-3), and granulocyte-macrophage colony-stimulating factor (GM-CSF) alone or in combination daily for 6 days. Day-12 colony-forming units-spleen (CFU-S) and marrow-derived colony-forming units-granulocyte/macrophage (CFU-GM) were assessed. Bone marrow cells from primary transplant recipients were transplanted into a secondary group of lethally irradiated mice, and the number of spleen colonies arising after 12 days' engraftment was determined as pre-CFU-S. SCF alone did not increase spleen colony formation in either primary or secondary recipients. In contrast, treatment of primary recipients with SCF and GM-CSF or IL-3 or with all three cytokines resulted in a synergistic increase of CFU-S in secondary recipients, indicating increased pre-CFU-S levels. The cytokine combinations also produced synergistic increases of CFU-GM in primary recipient marrow. Evaluation of spleen colonies in secondary recipients by PCR amplification of the Y-chromosome sex-determining region indicated that about 80% were of donor (male) origin. We conclude that SCF with IL-3 and/or GM-CSF increases pre-CFU-S proliferation.

Variable transcription of BCR-ABL by Ph+ cells arising from hematopoietic progenitors in chronic myeloid leukemia

Recent studies suggest that the BCR-ABL gene plays a critical role in the pathogenesis of Ph+ chronic myeloid leukemia (CML). We investigated the hematopoietic colonies derived from the marrows of 12 patients with Ph+ CML in chronic phase by reverse transcriptase-polymerase chain reaction (RT-PCR) amplification of BCR-ABL mRNA and by cytogenetics. Colonies were individually harvested and each colony divided into two portions, one for cytogenetics and the other for isolation of total RNA for PCR of BCR-ABL transcripts and for an RNA internal control. We found that 23% +/- 18% (mean +/- SD, range 0% to 60%) of Ph+ colonies did not transcribe the aberrant gene. In each case when BCR-ABL transcription was not detected, normal ABL mRNA was present. The data suggest that hitherto unknown mechanisms may regulate BCR-ABL expression in some Ph+ cells and indicate that caution should be exercised in the interpretation of results using RT-PCR analysis of hematopoietic colonies from clinical specimens and from experiments with antisense oligonucleotides directed at the BCR-ABL gene. These data also raise the notion of a transitional Ph+ precursor cell in which BCR-ABL may become upregulated and lead to a fully expressed phenotype. We conclude that further studies correlating the frequency of Ph+ PCR- progenitors with prognostic clinical variables are warranted.

Hematopoietic cytokines enhance survival of SCID mice undergoing high-dose irradiation

We have investigated the effect of hematopoietic cytokines on the survival of severe combined immune-deficient (SCID) mice that received a high dose of radiation. In this study, female SCID mice were irradiated at doses ranging from 500 to 600 cGy and then transplanted with 2 x 10(6) male Balb/c marrow cells. Groups of transplant recipients received stem cell factor (SCF), interleukin-1 (IL-1), and IL-3, alone or in combination, once daily for 5 days immediately after irradiation. Control posttransplant SCID recipients did not survive more than 2 weeks after irradiation with the dose over 500 cGy. SCF alone did not enhance survival, and treatment with IL-1 or IL-3 had very limited capacity to improve survival. IL-1 plus IL-3 has some radioprotective effect on SCID recipients, but the strongest synergistic radioprotective effect was observed in mice treated with a combination of SCF, IL-1, and IL-3. These mice survived for more than 4 months after an irradiation dose up to 600 cGy. We also examined the origin of hematopoietic stem cells in transplant recipients. Bone marrow cells were obtained from the SCID mice treated with a combination of cytokines at 2 and 4 months after transplant with male Balb/c marrow cells and irradiation with 600 cGy. These marrow cells were then transplanted into secondary lethally irradiated female Balb/c recipients. Twelve-day spleen colonies (CFU-S) were analyzed by amplification of the Y-chromosome sequence of the sex-determining region by polymerase chain reaction (PCR). All spleen colonies were of donor origin, indicating that the SCID recipients were fully reconstituted by donor cells. The results suggest that SCF, synergistic with IL-1 and IL-3, protects SCID mice from lethal doses of radiation and allows complete long-term engraftment of SCID recipients.

Peripheral neuropathy following high-dose etoposide and autologous bone marrow transplantation

We investigated the incidence of peripheral neuropathy in 142 consecutive patients receiving high-dose etoposide between August 1988 and December 1991. A retrospective chart review was conducted. Six patients with hematologic malignancies presented with a new sensory polyneuropathy after receiving an intensive therapy regimen consisting of etoposide 60 mg/kg i.v. and melphalan 140-160 mg/m2 i.v. followed by autologous bone marrow transplantation. Neurologic symptoms began 2-8 weeks after transplant, were grade 2-3 in severity and pursued a chronic course with slow improvement over months. Electromyographic studies in three of the patients tested confirmed distal sensory polyneuropathy. All 6 patients had previously received vincristine 1-60 months prior to autotransplant. We conclude that peripheral neuropathy of moderate severity is a potential complication of high-dose etoposide therapy but appears to be self-limited.

Detection and direct sequence identification of BCR-ABL mRNA in Ph+ chronic myeloid leukemia

The reverse transcriptase-polymerase chain reaction (RT-PCR) for BCR-ABL mRNA is increasingly used to diagnose and monitor patients with Ph+ chronic myeloid leukemia (CML). We investigated an alternative approach to detect BCR-ABL mRNA in CML in order to overcome some of the potential drawbacks of RT-PCR. Nucleic acid sequence based amplification (NASBA) is a homogeneous, isothermal, in vitro process that provides the direct amplification of RNA. Peripheral blood from seven patients with Ph+ CML and Ph+ EM-2 cells were investigated by NASBA and RT-PCR. A nested set of four primers flanking the BCR-ABL junction was used in two serial NASBA reactions performed for 2 hours. The two methods were fully concordant for detection of transcripts with bcr3-abl2 and bcr2-abl2 junctions. Ethidium bromide fluorescence with NASBA indicated in repeated experiments that similar quantities of total RNA from patient material contained different amounts of BCR-ABL mRNA. The data suggest that direct amplification of RNA is suitable for identifying and monitoring patients with Ph+ CML and may provide a means to quantify BCR-ABL mRNA levels.