Elimination of chemoresistant multiple myeloma clonogenic colony-forming cells by combined treatment with a plasma cell-reactive monoclonal antibody and a P-glycoprotein-reactive monoclonal antibody.

Patients with multiple myeloma (MM) commonly become refractory to chemotherapy despite a favorable response to induction treatment. We examined the effectiveness of a previously characterized plasma cell-reactive monoclonal antibody, MM4, in eliminating MM clonogenic colony-forming cells (CCC) with a multidrug-resistant (MDR) phenotype. Experiments were performed using MM cell lines that exhibit 6 (RPMI 8226/DOX6)- and 40 (RPMI 8226/DOX40)-fold resistance to doxorubicin (DOX). Both lines were selected from the chemosensitive MM line RPMI 8226/S and were cross-resistant to mitoxantrone, acronycine, etoposide, and vincristine. Surface marker analysis conducted in this study showed that DOX6 and DOX40 overexpressed the MDR1 gene product p170. Both MDR lines remained reactive to the plasma cell-reactive monoclonal antibodies MM4 and PCA-1 and expressed the relevant cytoplasmic immunoglobulin light chain. Treatment with MM4 and rabbit complement (C') was equally cytotoxic to RPMI 8226/S [80 +/- 5.6% (SD)], DOX6 [74 +/- 8.5], and DOX40 cells [75 +/- 11.3%], based on short-term chromium release studies. Furthermore, MM4 + C' deleted up to 3 logs of CCC colonies from chemosensitive and MDR lines (RPMI 8226/S, 99.87 +/- 0.11%; DOX6, 99.91 +/- 0.08%; DOX40, 99.55 +/- 0.44%). By comparison, the P-glycoprotein-reactive monoclonal antibody MRK-16 and C' inhibited tumor colony formation of MDR cells (8226/DOX6, 95.71 +/- 2.51%; 8226/DOX40, 99.61 +/- 0.43%) but affected that of chemosensitive cells only slightly (8.9 +/- 17.8%). In an attempt to optimize the depletion of myeloma CCC, MM4 was used together with MRK-16. This approach resulted in uniform depletion of myeloma clonogenic colony-forming cells from the chemosensitive (98.32 +/- 1.53%, n = 4) and MDR lines (8226/DOX6, 98.83 +/- 0.08%, n = 4; 8226/DOX40 99.29 +/- 0.62, n = 7) but did not result in enhanced CCC depletion. When DOX40 cells were mixed with normal bone marrow (BM) in the ratio of 90:10 (BM:MM), either MM4 or MRK-16 and C' depleted MM colonies (98.8 +/- 0.71% and 98.10 +/- 1.0%, respectively) without affecting the majority of BM progenitor cells. These observations suggest that either MM4 or MRK-16 is useful for depleting MDR myeloma clonogenic colony-forming cells.

Facilitated light microscopic cytochemical diagnosis of acute myelogenous leukemia.

Hydroperoxidase-positive Phi bodies and rods are much more prominent and prevalent than rods visualized with a Romanovsky-type stain (Auer rods) in immature leukocytes of patients with active acute myelogenous leukemia (AML). They are readily observed with the light microscope in peripheral blood or marrow films of AML patients stained to show their peroxidatic activity. In many of these patients, Auer rods, which apparently constitute only a small subpopulation of the hydroperoxidase-positive Phi bodies and rods, were detected with difficulty, if at all. The hydroperoxidase-positive Phi bodies and rods were observed in 92% of 36 patients with active disease. They were never observed in leukocytes of patients with other hematopoietic disorders or of normal individuals. Thus, they facilitated the distinction of AML from acute lymphocytic leukemia and chronic granulocytic leukemia in blast crisis. They were absent in full clinical remission after chemotherapy and were greatly diminished in partial remission. They were present in disease relapse and reappeared in five patients who had been in full remission. These results suggest that these hydroperoxidase-positive enlarged particles are pathognomonic of AML and that monitoring them with the light microscope may aid in guiding its clinical management.

High-dose chemotherapy, fractionated total-body irradiation, and allogeneic marrow transplantation for malignant lymphoma.

Seventeen patients with malignant lymphoma, including 13 with progressive disease and four in remission following primary chemotherapy, received high-dose chemotherapy, fractionated total-body irradiation (TBI), and allogeneic marrow transplants. Eleven of the 13 (85%) patients in relapse who received transplants achieved remission, and three remain disease free 41, 21, and 17 months later; one patient in second remission who received a transplant is disease free at 11 months. Thirteen patients are dead: four because of progressive lymphoma, seven because of interstitial pneumonitis, and two because of complications of severe acute graft-v-host disease. These results are similar to those noted in marrow transplantation series for advanced acute leukemia; since transplantation during remission has decreased relapse and improved survival in leukemia, earlier transplantation may produce improved results in lymphoma patients as well. However, the effectiveness of conventional therapy regimens for most lymphomas and the high incidence of severe transplant-related complications usually limit allogeneic transplantation to lymphoma patients in situations other than consolidation of first remission. Initial partial remission, early relapse from an initial remission, and perhaps second remission are situations in which conventional therapy is often ineffective, but the adverse features of very advanced lymphoma are not present; marrow transplantation may be considered in eligible patients. Transplant recipients with more advanced disease are anticipated to have poorer survivals.

Intensive 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU) monochemotherapy and autologous marrow transplantation for malignant glioma.

Intensive monochemotherapy with carmustine (BCNU) (either 1,050, 1,200, or 1,350 mg/m2) and cryopreserved autologous marrow transplantation was administered to 36 patients with malignant glioma: 27 with progressive disease and nine without progression (adjuvant therapy group). Twelve (44%) of the patients with progressive disease responded; two remain disease free 84 and 60 months after BCNU treatment. In the adjuvant therapy group, three patients remain progression free at 70, 48, and 27 months after BCNU therapy. Tumor progression posttransplantation occurred in 25 patients; six others died of therapy-induced complications. In addition, late neurologic deterioration of unknown cause has developed in two surviving patients. Results from this and other series using intensive BCNU monochemotherapy and autologous marrow transplantation for progressive malignant glioma indicate that prolonged progression-free survival can be produced in an occasional patient, an extremely unusual result with conventional chemotherapy. Although intensive BCNU and autologous marrow transplant regimens are toxic, these results are encouraging. The treatment of patients in an adjuvant fashion with BCNU and other active agents may produce improved results.

High-dose thiotepa with autologous bone marrow transplantation for metastatic malignant melanoma: results of phase I and II studies of the North American Bone Marrow Transplantation Group.

We evaluated thiotepa in escalating dose in a broad phase I and II study using cryopreserved autologous bone marrow transplantation to assure hematopoietic recovery. Thiotepa was administered intravenously (IV) over two hours daily for three consecutive days followed in three to four days by marrow transplantation. The daily dose ranged from 60 to 525 mg/m2 (total dose, 180 to 1,575 mg/m2). A total of 71 patients with malignant melanoma were treated. Forty-three patients (61%) had received prior cytotoxic therapy and 28 were untreated. Sixty-two patients (87%) had melanoma disseminated to at least one visceral site, nine patients had skin and/or lymphatic metastases only. As of January 1, 1988 one patient was too early to be evaluated, 15 patients were inevaluable for tumor response, four patients had a complete response (CR), and 25 patients had a partial response (PR) to treatment. The response rates (95% confidence interval) for the 55 evaluable patients and for all 71 treated patients were 53% (40% to 65%) and 41% (30% to 53%), respectively. The median duration of response was 3 months, with a range of 1 to 31 + months. Three patients were alive and well without evidence of tumor more than 1 year after treatment. Analysis of patient subsets indicated that neither total dose, previous cytotoxic therapy, or sites of metastases influenced response rate. In this study, high-dose thiotepa has demonstrated a high response rate in patients with metastatic malignant melanoma with both PRs and CRs noted. Although most of the responses were not durable, 10% of the responses lasted more than 1 year. Future studies will evaluate additional methods for increasing the response rate and improving the duration of response.

Intensive chemotherapy with cyclophosphamide, carmustine, and etoposide followed by autologous bone marrow transplantation for relapsed Hodgkin's disease.

Fifty-six consecutive patients with advanced Hodgkin's disease considered incurable with further conventional chemotherapy were entered into a protocol that included high-dose cyclophosphamide (7.2 g/m2), carmustine (BCNU; 0.6 g/m2), and etoposide (VP16-213; 2.4 g/m2) (CBV) followed by autologous bone marrow transplantation (BMT). Prior combination chemotherapy had failed in all the patients, and all but five had been previously treated with both mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) and doxorubicin, bleomycin, and vinblastine with or without dacarbazine (ABV[D]). Thirty-four eligible patients received short-course conventional chemotherapy and/or involved-field radiotherapy before CBV. However, formal restaging was not performed after these conventional therapies; ie, the therapies were not used to select responding patients for transplantation, and all who received such therapy subsequently received CBV and autologous marrow grafts. Forty-four patients (80%; 95% confidence interval [CI], 69% to 91%) achieved a complete response after CBV and BMT. Performance status at protocol entry and the use of conventional cytoreduction therapy before CBV correlated with response. Median follow-up is now 3.5 years (range, 2.5 to 5.0 years). Kaplan-Meier estimates for overall and event-free survival 5 years after transplant are 53% (95% CI, 37% to 67%) and 47% (95% CI, 33% to 60%), respectively. In a univariate analysis, patients with a normal performance status and those without constitutional ("B") symptoms at protocol entry had an improved overall and event-free survival. In a multivariate analysis, only a normal performance status remained significant. Disease progression occurred in 17 patients at an actuarial rate of 39% (95% CI; 26% to 56%) and occurred at previous sites of active disease in all but one patient; our analysis did not identify prognostic factors for progression. Toxic deaths, caused by either neutropenic sepsis or interstitial pneumonitis (IP), occurred in 12 patients (21%; 95% CI, 10% to 32%). CBV with autologous marrow support can produce durable remissions in a substantial number of patients with Hodgkin's disease considered incurable with conventional measures. Regimen refinements may even further improve the therapeutic index of BMT in this malignancy.

Allogeneic marrow transplantation for refractory Hodgkin's disease.

Eight patients with refractory Hodgkin's disease received intensive combination chemotherapy conditioning with cyclophosphamide, carmustine (BCNU), and etoposide (VP 16-213), and allogeneic marrow transplants. All patients achieved complete responses. Three patients relapsed; two died of Hodgkin's disease and one of chronic graft-v-host disease (GVHD) and infection. In all, four patients died due to transplant-related toxicity. One patient developed a fatal B-cell lymphoproliferative disorder soon after transplantation, and died without evidence of Hodgkin's disease. One patient is alive and free of progression 29 months after transplantation. These data indicate that allogeneic marrow transplantation may be considered as therapy for selected patients with advanced Hodgkin's disease and, despite substantial toxicity, will occasionally result in long-term responses. Better patient selection would likely improve results.

High-dose cytarabine and daunorubicin as consolidation therapy for acute myeloid leukemia in first remission: long-term follow-up and results.

In an effort to increase the proportion of patients with acute myeloid leukemia (AML) remaining in continued complete remission (CCR), we administered intensive postremission consolidation therapy with high-dose cytarabine (Ara-C) and daunorubicin. Eighty-seven patients, with a median age of 38 years (range, 7 to 71), received consolidation therapy after first complete remission was obtained with standard induction chemotherapy that included conventional doses of Ara-C. Consolidation therapy consisted of from one to three cycles of high-dose Ara-C (3 g/m2 intravenously [IV] over 1 hour every 12 hours for 12 doses) followed by daunorubicin (30 mg/m2/d IV bolus for 3 days). After completion of the high-dose Ara-C and daunorubicin, no further therapy was administered. Myelosuppression encountered with consolidation resulted in a median duration of neutropenia and thrombocytopenia of 3 weeks. Four patients (5%) died during consolidation due to infection and/or hemorrhage; 59% of patients experienced severe but nonfatal infectious or extramedullary organ toxicity. With a median follow-up of more than 3.5 years from diagnosis, the proportion of patients, by Kaplan-Meier product-limit estimate, remaining in CCR is 49% (95% confidence limits, 37% to 61%). In a Cox multivariate analysis, only age significantly (P less than .001) influenced the probability of remaining in CCR. The probability of remaining in CCR was 83%, 50%, and 23% for age groups of 25 or less, 26 to 45, and more than 45 years, respectively. These survival curves all have stable long-term plateaus, suggesting cure. In this study, the administration of brief, intensive nonmarrow ablative chemotherapy resulted in a large proportion of patients with AML remaining in CCR, results similar to those reported with allogeneic bone marrow transplantation. Relapse of acute leukemia was still the major reason for therapy failure, suggesting that more effective or additional postremission therapy will be required to further improve the likelihood of cure especially for older patients.

High-dose chemotherapy with autologous hematopoietic stem-cell support for breast cancer in North America.

PURPOSE: To identify trends in high-dose therapy with autologous hematopoietic stem-cell support (autotransplants) for breast cancer (1989 to 1995). PATIENTS AND METHODS: Analysis of patients who received autotransplants and were reported to the Autologous Blood and Marrow Transplant Registry. Between January 1, 1989 and June 30, 1995, 19,291 autotransplants were reviewed; 5,886 were for breast cancer. Main outcomes were progression-free survival (PFS) and survival. RESULTS: Between 1989 and 1995, autotransplants for breast cancer increased sixfold. After 1992, breast cancer was the most common indication for autotransplant. Significant trends included increasing use for locally advanced rather than metastatic disease (P < .00001) and use of blood-derived rather than marrow-derived stem cells (P < .00001). One-hundred-day mortality decreased from 22% to 5% (P < .0001). Three-year PFS probabilities were 65% (95% confidence intervals [Cls], 59 to 71) for stage 2 disease, and 60% (95% Cl, 53 to 67) for stage 3 disease. In metastatic breast cancer, 3-year probabilities of PFS were 7% (95% Cl, 4 to 10) for women with no response to conventional dose chemotherapy; 13% (95% Cl, 9 to 17) for those with partial response; and 32% (95% Cl, 27 to 37) for those with complete response. Eleven percent of women with stage 2/3 disease and less than 1% of those with stage 4 disease participated in national cooperative group randomized trials. CONCLUSION: Autotransplants increasingly are used to treat breast cancer. One-hundred-day mortality has decreased substantially. Three-year survival is better in women with earlier stage disease and in those who respond to pretransplant chemotherapy.

Modification of the Bu/Cy myeloablative regimen using daily parenteral busulfan: reduced toxicity without the need for pharmacokinetic monitoring.

Pharmacokinetic and clinical outcome measures among three groups of patients undergoing hematopoietic transplant were assessed: group A: Parenteral busulfan (Bu) 3.2 mg/kg i.v. given qd, n=20; group B: parenteral Bu 0.8 mg/kg i.v. given every 6 h, n=11; group C: Bu 1 mg/kg p.o. given every 6 h, n=25. All groups received Bu over 4 days followed by Cy 60 mg/kg i.v. qd over 2 days; followed by an infusion of allogeneic stem cells. Median Bu clearance was 3.21 ml/min/kg and median daily AUC was 4071 micromol/min for the group A patients. The dosing formula for Bu i.v. qd was highly predictive of the AUC for patients whose mass < or =IBW+20%. For patients of greater mass, the dosing formula uniformly resulted in lower-than-predicted AUC. Neurologic toxicity, hepatic toxicity, hematologic engraftment, and relapse at 100 days were comparable across all three groups. Severe AGVHD was least among group A, followed by group B when compared with group C. Bu i.v. qd is a safe and effective regimen for allogeneic transplantation and is at least clinically equivalent to every 6 h dosing schemes using either oral or parenteral Bu.

Autologous marrow transplantation for patients with acute myelogenous leukemia--a preliminary report.

Twelve consecutive adult patients with acute myelogenous leukemia have been entered on a treatment protocol which examines the role of "remission-intensification" during maintenance using high-dose chemoradiotherapy and autologous remission marrow transplantation. Nine patients have achieved complete remission: 5/9 patients have had remission marrow stored followed by high-dose chemoradiotherapy and autologous marrow transfusion; two patients were removed from study because of excessive toxicity during remission-induction precluding high-dose therapy; two patients are currently ready for marrow storage; and two patients are receiving remission-induction therapy. Of the five transplanted patients, four experienced excellent return of blood counts and one patient has had prolonged pancytopenia and continues to require red cell and platelet transfusions. There have been no serious infectious or hemorrhagic problems associated with post-transplant period in any of the patients. Autologous remission bone marrow transplantation following lethal high-dose chemoradiotherapy results in effective restoration of normal hemopoiesis, is associated with acceptable toxicity and may be an effective means of increasing the numbers of acute leukemia patients having long-term complete remission.

Intensive 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) autologous bone marrow transplantation therapy of refractory cancer: a preliminary report.

Eighteen patients with refractory malignancies were treated with escalating doses of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and autologous bone marrow transplants (BMTX). Hematopoietic recovery was similar with doses of 300mg/m2qd X 3 and 500mg/m2qd X 3 providing suggestive evidence of a myeloprotective effect of the BMTX. Extramedullary toxicity was sporadic but occasionally severe; pulmonary fibrosis and severe cholestatic jaundice were seen in one case each. Antitumor responses were noted in patients with brain tumors, melanoma, hematological neoplasms and lung cancer.

Recombinant human interleukin-3 and granulocyte-macrophage colony-stimulating factor after autologous bone marrow transplantation for malignant lymphoma.

Recombinant human interleukin-3 (rhIL-3), granulocyte-macrophage colony-stimulating factor (rhGM-CSF), and granulocyte colony-stimulating factor (rhG-CSF) enhance neutrophil recovery following autologous bone marrow transplantation (ABMT) for malignant lymphoma. Based on findings in preclinical studies, a phase I-II trial was conducted to assess the safety and efficacy of the sequential administration of rhIL-3 and rhGM-CSF after bone marrow ablative cytotoxic therapy and ABMT for patients with malignant lymphoma. Thirty-seven patients (20 with non-Hodgkin's lymphoma and 17 with Hodgkin's disease) were treated with intensive cytotoxic therapy before ABMT. Patients were treated in one of four cohorts to receive rhIL-3 (2.5 or 5.0 microg/kg/d) administered by subcutaneous injection for either 5 or 10 days following ABMT. Twenty-four hours after the last dose of rhIL-3, rhGM-CSF (250 microg/m2/d as a 2-hour intravenous infusion) administration was initiated. Sequential cytokine therapy post-ABMT resulted in fewer days of platelet and red blood cell transfusions than seen in historic controls with rhIL-3, rhGM-CSF, or rhG-CSF monotherapy. These data suggest that the sequential administration of rhIL-3 and rhGM-CSF after ABMT results in rapid recovery of multilineage hematopoiesis.

Dose-intensive chemotherapy with etoposide-cyclophosphamide for advanced breast cancer. North American Marrow Transplant Group.

Bone marrow and extensive bone involvement have limited the use of chemotherapy with stem cell support for treatment of women with metastatic breast cancer. The toxicity and efficacy of dose-intensive chemotherapy were studied using etoposide and cyclophosphamide without a stem cell support regimen for women with advanced breast cancer. The regimen was well tolerated, with treatment-related mortality similar to dose-intensive therapy with stem cell support. The overall 58% response rate is comparable to the response rate with dose-intensive chemotherapy regimens using stem cell support. The extent of disease, responsiveness to standard therapy, and dose of etoposide affected the response rate. Hematopoietic recovery was fairly prompt and was generally unaffected by the use of hematopoietic growth factors or the presence of breast cancer cells in the marrow. The use of stem cells or recombinant human interleukin-3 (rhIL-3) in combination with recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) resulted in some benefit in neutrophil recovery. It was concluded that in many women with advanced breast cancer, a dose-intensive regimen of etoposide and cyclophosphamide results in response or stabilization of disease. Hematopoietic recovery, particularly platelet recovery, may be accelerated by a combination of rhIL-3 and rhGM-CSF.

High-dose N,N',N"-triethylenethiophosphoramide (thiotepa) with autologous bone marrow transplantation: phase I studies.

N,N',N''-triethylenethiophosphoramide (thiotepa) is a polyfunctional alkylating agent similar in structure to nitrogen mustard. Thiotepa (synthesized by American Cyanamid Company, Wayne, NJ) underwent clinical trials in the 1960s that showed that it was active against a wide variety of tumors. At a standard dose level (10 to 30 mg/m2), the dose-limiting toxicity is myelosuppression; other toxicities are infrequent. Therefore, high-dose phase I evaluation was encouraged by these observations. Approximately 217 patients have been treated with single-agent high-dose thiotepa administered intravenously daily over 2 hours for 3 days followed by hematopoietic stem cell rescue to prevent prolonged myelotoxicity. The total doses administered ranged from 135 to 1,575 mg/m2. As anticipated, myelotoxicity was substantial, with 180 mg/m2 being the highest dose not requiring stem cell rescue to ensure hematopoietic recovery. Extramedullary toxicities consisted of stomatitis, dermatitis, hepatoxicity, and central nervous system (CNS) toxicity. CNS toxicity was dose-limiting; other toxicities were problematic, ie, dose-dependent but not truly dose-limiting. The maximal tolerated dose of thiotepa is 900 to 1,125 mg/m2, with the lower dose being the maximal dose for evaluation in combination chemotherapy. In high-dose phase I evaluation, the overall response rate was approximately 50% with responses seen in a wide variety of solid tumors, lymphomas, and pediatric tumors. High-dose thiotepa appears to be an alkylating agent with broad-spectrum antitumor efficacy, which should add to the cytoreductive regimens for both solid and hematopoietic tumors.

Characterization of skin-infiltrating cells during acute graft-versus-host disease following bone marrow transplantation using unrelated marrow donors.

To characterize skin-infiltrating T lymphocytes during acute GVHD, skin biopsies were obtained from two patients who received unrelated marrow matched for HLA-A, -B, -DR, and -DQ but mismatched for -DP. A total of 120 T-cell clones were generated. Phenotype analysis of the clones showed that the majority of cells were CD4+ and expressed alpha/beta TCR. HLA-DP oligonucleotide genotyping of the clones revealed the presence of lymphoid chimerism. PLT assay showed the lack of HLA specificity, including mismatched HLA-DP. However, mAb to HLA antigens blocked proliferation of the majority of the clones, indicating that the clones recognized HLA-associated molecules. Interestingly, proliferation of two CD4+ T-cell clones was inhibited by class I mAb. A few of the clones revealed augmented proliferation in the presence of CMV antigens and a few revealed cytolytic activity. The above study suggests that (a) CD4+ helper T cells may be primarily responsible for immunopathogenesis of skin manifestations during acute GVHD, (b) there is a mixed lymphoid chimerism in skin during acute GVHD, (c) HLA-DP may not be a factor contributing to the development of acute GVHD, (d) the peptide of the HLA groove or superantigen associated with HLA molecules may be the stimulatory antigen, and (e) CMV antigens appear to stimulate some of the skin-infiltrating T lymphocytes.

Hematologic relapse of chronic myelogenous leukemia following allogeneic bone marrow transplantation: apparent graft-versus-leukemia effect following abrupt discontinuation of immunosuppression.

Two patients with hematologic relapse of chronic myelogenous leukemia (CML) following allogeneic BMT were treated by abrupt discontinuation of cyclosporine. Both patients rapidly attained complete hematologic and cytogenetic remission and remain free of disease with long follow-up. In the first patient, disappearance of CML was associated with the development of graft-versus-host disease (GVHD). In the second patient GVHD did not develop until after clearing of disease had been documented by cytogenetic analysis. Laboratory studies in the second patient disclosed the presence of lytic activity against both K562 and autologous CML cells that enhanced with IL2. Correlation with serial immunophenotyping data from this patient suggests that the effector for this graft-versus-leukemia (GVL) reaction could have been a T lymphocyte. Abrupt discontinuation of post-transplant immunosuppression with cyclosporine may represent a therapeutic approach to CML which has recurred following BMT. Moreover, investigation of this clinical phenomenon in subsequent cases may permit direct study of the cellular mechanisms involved in the GVL effect.

Treatment of T prolymphocytic leukemia with allogeneic bone marrow transplantation.

T prolymphocytic leukemia (T-PLL) is an unusual disease characterized by high white cell counts, older age at presentation, splenomegaly and a very aggressive clinical course. We describe a 47-year-old male with refractory T-PLL who was treated with high-dose chemoradiotherapy and allogeneic bone marrow transplantation (BMT) from an HLA-matched sibling. The transplant was complicated by both acute and chronic graft-versus-host disease (GVHD). The patient achieved complete remission and remains in remission 3 years after the transplant.

Lack of interaction between tacrolimus (FK506) and methotrexate in bone marrow transplant recipients.

Tacrolimus (FK506) is a macrolide lactone effective in the control of graft-versus-host disease (GVHD). An interaction between high-dose methotrexate and a macrolide antibiotic (pristinamycin) leading to prolonged methotrexate exposure has been described. Because a randomized prospective trial comparing tacrolimus with cyclosporine (both in combination with methotrexate) following allogeneic BMT showed the tacrolimus plus methotrexate regimen to be more effective in prevention of GVHD, we assessed methotrexate pharmacokinetics in a subgroup of the participants of this trial to evaluate the possibility that an interaction of FK506 and methotrexate was the explanation for the clinical findings. Mean and median methotrexate levels at various time-points after the day 1 and 6 methotrexate doses were comparable in the tacrolimus and cyclosporine cohorts and were elevated in only three of 70 study patients. Area under the curve (AUC) concentrations were also similar after the day 1 and 6 methotrexate doses. Thus, no significant interaction between tacrolimus and methotrexate is apparent and the differences in efficacy between tacrolimus and cyclosporine are unlikely to be attributable to pharmacologic interactions with methotrexate.

Elimination of leukemic cells by laser photodynamic therapy.

We studied the effects of 514-nm laser light-induced merocyanine 540 (MC540)-mediated toxicity on both leukemic and normal bone marrow (BM) cells. Acute promyelocytic leukemia (HL-60) cells were incubated with MC540 (20 micrograms/ml) and exposed to 93.6 J/cm2 irradiation at a 514-nm wavelength. Normal bone marrow cells were treated under similar conditions. At this dose, 99.9999% of the leukemic cells were killed while 55% of the BM cell survived. Of the granulocyte-macrophage colony-forming cells (CFU-GM), 27% also survived this treatment. Photosensitization of a mixture of irradiated BM cells mixed with an equal number of nonirradiated HL-60 cell did not interfere with the killing of HL-60 cells. There was no significant reduction in the viability of cells when exposed to the laser light alone. In summary, laser light-induced photosensitization with MC540 has a selective cytotoxicity to leukemic cells; therefore, this procedure may be useful for purging neoplastic cells from autologous BM.