Treatment of Multiple Myeloma with Autologous Blood Stem Cell Transplantation. Preliminary Results of an Italian Multicentric Pilot Study

Starting from May, 1991, 35 untreated myeloma patients entered a multicentric pilot study to evaluate the feasibility of a program of PBSC transplantation for previously untreated myeloma patients. The schedule was as follows: 2 cycles of VAD followed by CY, 7 g/mq + G-CSF (Granulokine, Roche) for 14 days, to increase and collect PBSC. The subsequent conditioning regimen was Melphalan + Busulfan followed by G-CSF. As maintenance R alpha-2 IFN was given, until relapse. The median follow-up is 14 months (4-22). On April 1993, 34 patients received at least 2 cycles of VAD, 27 were submitted to PBSC collection, 22 received conditioning regimen plus PBSC and 16 of them are in the maintenance treatment with IFN. Considering 28 patients for an intention to treat evaluation (35 -7 in treatment), responding patients are 71% with 46% who achieved CR. White cells and platelets raised to > 1000/mmc and >50,000/mmc after a median period of 10 and 13 days, from CY, and 11 and 14 days from transplant, respectively. Two patients relapsed, 2 others died while in PR because of CMV epatitis and candida pneumonia. The median number of CD34+ cells and CFU-GM was 24.75 x 106/kg b.w. and 28.1 x 104/kg b.w. respectively. In conclusion this treatment seems to be feasible and with low toxicity, but a longer follow-up is needed to evaluate the progression free survival of the high proportion of responding patients that we observed.

Autologous transplant vs oral chemotherapy and lenalidomide in newly diagnosed young myeloma patients: a pooled analysis

In newly diagnosed myeloma patients, upfront autologous transplant (ASCT) prolongs progression-free survival 1 (PFS1) compared with chemotherapy plus lenalidomide (CC+R). Salvage ASCT at first relapse may still effectively rescue patients who did not receive upfront ASCT. To evaluate the long-term benefit of upfront ASCT vs CC+R and the impact of salvage ASCT in patients who received upfront CC+R, we conducted a pooled analysis of 2 phase III trials (RV-MM-209 and EMN-441). Primary endpoints were PFS1, progression-free survival 2 (PFS2), overall survival (OS). A total of 268 patients were randomized to 2 courses of melphalan 200 mg/m² and ASCT (MEL200-ASCT) and 261 to CC+R. Median follow-up was 46 months. MEL200-ASCT significantly improved PFS1 (median: 42 vs 24 months, HR 0.53; P<0.001), PFS2 (4 years: 71 vs 54%, HR 0.53, P<0.001) and OS (4 years: 84 vs 70%, HR 0.51, P<0.001) compared with CC+R. The advantage was noticed in good and bad prognosis patients. Only 53% of patients relapsing from CC+R received ASCT at first relapse. Upfront ASCT significantly reduced the risk of death (HR 0.51; P=0.007) in comparison with salvage ASCT. In conclusion, these data confirm the role of upfront ASCT as the standard approach for all young myeloma patients.

A phase 2 study of three low-dose intensity subcutaneous bortezomib regimens in elderly frail patients with untreated multiple myeloma

This phase 2 trial evaluated three low-dose intensity subcutaneous bortezomib-based treatments in patients ⩾75 years with newly diagnosed multiple myeloma (MM). Patients received subcutaneous bortezomib plus oral prednisone (VP, N=51) or VP plus cyclophosphamide (VCP, N=51) or VP plus melphalan (VMP, N=50), followed by bortezomib maintenance, and half of the patients were frail. Response rate was 64% with VP, 67% with VCP and 86% with VMP, and very good partial response rate or better was 26%, 28.5% and 49%, respectively. Median progression-free survival was 14.0, 15.2 and 17.1 months, and 2-year OS was 60%, 70% and 76% in VP, VCP, VMP, respectively. At least one drug-related grade ⩾3 non-hematologic adverse event (AE) occurred in 22% of VP, 37% of VCP and 33% of VMP patients; the discontinuation rate for AEs was 12%, 14% and 20%, and the 6-month rate of toxicity-related deaths was 4%, 4% and 8%, respectively. The most common grade ⩾3 AEs included infections (8-20%), and constitutional (10-14%) and cardiovascular events (4-12%); peripheral neuropathy was limited (4-6%). Bortezomib maintenance was effective and feasible. VP, VCP and VMP regimens demonstrated no substantial difference. Yet, toxicity was higher with VMP, suggesting that a two-drug combination followed by maintenance should be preferred in frail patients.

Evolution of bisphosphonate-related osteonecrosis of the jaw in patients with multiple myeloma and Waldenstrom's macroglobulinemia: a retrospective multicentric study

Bisphosphonates (BPs) are used intravenously to treat cancer-related conditions for the prevention of pathological fractures. Osteonecrosis of the jaw (BRONJ) is a rare complication reported in 4-15% of patients. We studied, retrospectively, 55 patients with multiple myeloma or Waldenstrom's macroglobulinemia followed up from different haematological departments who developed BRONJ. All patients were treated with BPs for bone lesions and/or fractures. The most common trigger for BRONJ was dental alveolar surgery. After a median observation of 26 months, no death caused by BRONJ complication was reported. In all, 51 patients were treated with antibiotic therapy, and in 6 patients, this was performed in association with surgical debridement of necrotic bone, in 16 with hyperbaric O(2) therapy/ozonotherapy and curettage and in 12 with sequestrectomy and O(2)/hyperbaric therapy. Complete response was observed in 20 cases, partial response in 21, unchanged in 9 and worsening in 3. The association of surgical treatment with antibiotic therapy seems to be more effective in eradicating the necrotic bone than antibiotic treatment alone. O(2) hyperbaric/ozonotherapy is a very effective treatment. The cumulative dosage of BPs is important for the evolution of BRONJ. Because the most common trigger for BRONJ was dental extractions, all patients, before BP treatment, must achieve an optimal periodontal health.

Stem cell mobilization in patients with newly diagnosed multiple myeloma after lenalidomide induction therapy

Lenalidomide has raised concerns regarding its potential impact on the ability to collect stem cells for autologous stem cell transplantation, especially after prolonged exposure. The use of cyclophosphamide plus granulocyte colony-stimulating factor (G-CSF) to mobilize peripheral blood stem cells may overcome this concern. In newly diagnosed multiple myeloma (MM) patients, we investigated the influence of lenalidomide on stem cell collection. In a prospective study, 346 patients received four cycles of lenalidomide-dexamethasone (Rd). Stem cells were mobilized with cyclophosphamide and G-CSF. Patients failing to collect a minimum of 4 × 10(6) CD34(+)/kg cells received a second mobilization course. After mobilization, a median yield of 8.7 × 10(6) CD34(+)/kg was obtained from patients receiving Rd induction. After first mobilization, inadequate yield was observed in 21% of patients, whereas only 9% of patients failed to collect the target yield after the second mobilization attempt. In conclusion, we confirm that a short induction with lenalidomide allowed sufficient stem cells collection to perform autologous transplantation in 91% of newly diagnosed patients.

Previous thalidomide therapy may not affect lenalidomide response and outcome in relapse or refractory multiple myeloma patients

INTRODUCTION

Lenalidomide is a thalidomide analogue, designed to have improved efficacy and tolerability over the parent drug. The aim of this retrospective analysis is to evaluate the impact of thalidomide therapy on lenalidomide response and outcome in relapse or refractory multiple myeloma patients.

PATIENTS AND METHODS

A total of 106 relapsed or refractory multiple myeloma patients received lenalidomide 25mg plus dexamethasone as salvage therapy; 80 patients progressed on thalidomide treatment (thalidomide-resistant) and 26 patients discontinued thalidomide in at least partial remission (thalidomide-sensitive). Median time from diagnosis to lenalidomide treatment was 57 months. Median prior lines of therapies were 3, range 1-6. 62% of patients were previously treated with autologous stem cell transplantation, and 71% with bortezomib-based regimens.

RESULTS

In the thalidomide-resistant and -sensitive groups, the at least partial response rates were 56.2% and 61.5% (P = .45), including at least VGPR rates of 16.2% and 11.5%; the median progression free survival was 10 and 12 months (P=.12) and the median overall survival was 17 and 18.5 months (P = .50), respectively.

CONCLUSION

Lenalidomide may be equally effective in heavily pre-treated multiple myeloma patients who are thalidomide-resistant or thalidomide-sensitive to a previous therapy.

Vasculogenic mimicry by bone marrow macrophages in patients with multiple myeloma

Bone marrow macrophages of patients with active and nonactive multiple myeloma (MM), monoclonal gammopathies of undetermined significance (MGUS) and benign anemia (controls) were stimulated for 7 days with vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), and analysed for the expression of endothelial cell (EC) markers by reverse transcription (RT)-PCR, real-time RT-PCR, western blot and immunofluorescence. Their vasculogenic ability was investigated in vitro in a Matrigel assay and in vivo on bone marrow biopsies through dual immunofluorescence and confocal laser microscopy. Active MM macrophages exposed to VEGF and bFGF acquired EC markers and formed capillary-like structures mimicking paired bone marrow ECs (multiple myeloma patient-derived endothelial cells, MMECs), with major responsiveness compared to macrophages from nonactive MM, MGUS or controls. Bone marrow biopsies of active MM harbored 'mosaic' vessels, being formed by MMECs, EC-like macrophages and macrophages themselves. These figures were rare in nonactive MM and absent in MGUS or controls. Our data indicate that macrophages contribute to build neovessels in active MM through vasculogenic mimicry, and this ability proceeds parallel to progression of the plasma cell tumors. Macrophages may be a target for the MM antivascular treatment.

Factors predictive of outcome in relapsed, refractory multiple myeloma patients treated with bortezomib, melphalan, prednisone, and thalidomide (VMPT)

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Background: In relapsed/refractory multiple myeloma (MM) patients, the addition of thalidomide and bortezomib to the standard oral melphalan/prednisone (VMPT) significantly increased response rate and progression-free survival (PFS) (Blood. 2006 Dec 5; [Epub ahead of print]). Baseline parameters which may predict outcome after VMPT have been investigated to identify which patient subgroups most benefit from this drug combination. Methods: Thirty patients with relapsed or refractory MM after 1 or 2 lines of treatment, were treated with six 35-days courses of bortezomib (3 dose levels: 1.0,1.3 and 1.6 mg/m2) on days 1,4,15,22, plus melphalan (6 mg/m2) and prednisone (60 mg/m2) on days 1–5 and thalidomide (50 mg) on days 1–35. Several parameters such as age, β2-microglobulin, C-reactive protein, chromosome 13 abnormalities, albumin, haemoglobin, stage, creatinine, bone marrow plasmacytosis, line of therapy and dosage of bortezomib were analyzed in association with response rate and PFS, using χ2 and Cox model. Results: At least a very good partial response was achieved in 43% of patients and at least a partial response in 67%. The 1-year PFS was 61%, and the 1- year overall survival was 84%. Subgroup analyses did not show any statistical difference between responses and either age, β2 microglobulin, C-reactive protein, chromosome 13 abnormalities, line of treatment or dosage of bortezomib. Serum albumin <3.5 mg/dL was loosely associated with a lower response rate (p=0.09). Factors predictive of shorter PFS were C-reactive protein = 6 mg/L (p=0.02) and 3rd line of therapy (p=0.009). Factors loosely associated with shorter PFS were β2-microglobulin = 3.5 mg/L (p=0.06) and creatinine = 2 mg/dL (p=0.09). No difference in PFS was observed between patients with or without chromosome 13 abnormalities. Conclusions: VMPT induced a high proportion of responses and appeared to overcome the poor prognosis of patients with chromosome 13q deletion.

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Diagnosis of acute foetal distress does not preclude banking of umbilical cord blood units

Clinical diagnosis of acute foetal distress (AFD) is based on several parameters such as abnormal foetal heart rate (FHR) pattern and/or meconium liquid staining (MLS). Standards for cord blood (CB) banking indicate that AFD should be considered as exclusion criteria for CB collection, but precise guidelines on how to proceed with CB collection in the presence of AFD signs during labour are not available. We evaluated whether the presence of FHR abnormality and/or MLS during labour 1) reduced the CB collection activity; 2) were associated with the infant's acidaemia or asphyxia and 3) deteriorated the biological characteristics of CB units. Thirty-three units of CB were evaluated for biological parameters, gas values and newborn's Apgar score. The results were compared with a control group of 33 consecutive units previously banked. No differences were observed between the two groups and all but one newborn showed normal Apgar score and absence of metabolic acidaemia. The results showed that 1) AFD reduced the CB collection activity by 10% each year; 2) the majority of CB units collected in the presence of abnormal FHR and/or meconium have biological characteristics eligible for banking; 3) FHR alterations or meconium in the presence of normal gas analysis do not represent certain diagnosis of AFD.

Multiple myeloma: comparison of two dose-intensive melphalan regimens (100 vs 200 mg/m2)

Several trials have shown the superior impact of high-dose melphalan (usually 200 mg/m(2), MEL200) vs standard therapy in myeloma patients. Intermediate-dose melphalan (100 mg/m(2), MEL100) is also superior to the standard dose, but has not been clinically compared with MEL200. A total of 90 patients at diagnosis were treated with two MEL100 courses. Their clinical outcome was compared with that of a control group of 90 pair mates matched for serum beta2-microglobulin levels and Durie and Salmon clinical stage. These patients were treated at diagnosis with two MEL200 courses. Patient characteristics were similar in both groups except that the median age of the MEL100 group was significantly higher (P<0.0001). Complete remission was 35% after MEL100 and 48% after MEL200 (P=0.08). Median event-free survival (EFS) was 32 months in the MEL100 group and 42 months in the MEL200 group (P<0.005), but overall survival (OS) was not different. Transplant-related mortality was not significantly different. Haematological and extra-haematological toxicity was significantly reduced after MEL100. Despite the significant age difference, tandem MEL100 was less toxic than tandem MEL200, and MEL100 was inferior to MEL200 in terms of EFS but not in terms of OS. The intensified nonmyeloablative MEL100 regimen is an effective first-line treatment.

Quantitative analysis of Fas and bcl-2 expression in hematopoietic precursors

BACKGROUND AND OBJECTIVES

We investigated the expression of bcl-2 and CD95 (Apo1-/Fas) on CD34+ cells obtained from bone marrow (BM), mobilized peripheral blood (MPB), and umbilical cord blood (UCB) samples. The expression of bcl-2 and Fas was then compared with that of other markers usually associated with immaturity; functional tests using the agonistic antibody anti- Fas CH11 were also carried out.

DESIGN AND METHODS

The analysis was performed by flow cytometry on purified CD34+ cells in a three (CD95 PE, CD34 APC and CD71 FITC) and in a four (CD38 PE, HLA-DR PerCP, CD34 APC and bcl-2 FITC) fluorescence assay.

RESULTS

The results were expressed as mean fluorescence index (MFI); bcl-2 expression was significantly higher (p < 0.001) in BM (3.73 +/- 0.63) than in MPB (2.47 +/- 0.39) and UCB (2.38 +/- 0.58); Fas was significantly less expressed (p < 0.001) in UCB (1.27 +/- 0.78) than in MBP (3.63 +/- 2.19) and BM (4.56 +/- 1.69). CD34 expression was significantly (p < 0.001) brighter in UCB compared to in MBP and BM, while CD38 and CD71 were significantly (p = 0.005 and p < 0.001, respectively) more expressed in BM than in MPB and UCB. Fas values were directly correlated to CD38; both Fas and bcl-2 were directly related to CD71 and inversely to CD34. Culture assays showed that hematopoietic precursor cells from BM, MPB and UCB had a low susceptibility to undergo Fas-mediated apoptosis.

INTERPRETATION AND CONCLUSIONS

In conclusion, bcl-2 and Fas are less expressed in UCB than in MPB and BM; early hematopoietic precursor cells are relatively resistant to CD95-triggered apoptosis; the observed correlation between Fas/bcl-2 and markers of immaturity suggests that they may be determinants of commitment in early hematopoietic precursors.

Autologous peripheral blood stem cell transplantation as first line treatment of multiple myeloma: an Italian Multicenter Study

BACKGROUND AND OBJECTIVE

The outcome of patients with multiple myeloma (MM) has not changed markedly since the introduction of melphalan and prednisone. In recent years several studies have investigated the role of intensive therapy followed by infusion of autologous peripheral blood stem cells (PBSC) together with the administration of hematopoietic growth factors. In this study we evaluated the feasibility and efficacy of a PBSC transplantation program for patients with de novo MM in a multicenter setting.

DESIGN AND METHODS

In a non-randomized controlled trial 52 patients with de novo MM from 6 Italian centers underwent a three phase treatment strategy including 3 cycles of VAD-like chemotherapy for initial debulking, followed by high-dose cyclophosphamide (HD-CY) and collection of PBSC, that were transplanted after a conditioning regimen with melphalan plus busulfan. Maintenance treatment was a conventional dose of interferon, given until relapse. Actuarial survival and response duration curves were plotted according to Kaplan and Meier's method; the groups were compared using the log rank test. Response rates were compared by the c(2) test; multivariate analysis was performed according to the stepwise regression model.

RESULTS

Overall 39/52 (75%) of patients responded, with a complete remission (CR) rate of 31%. After a median follow-up of 55 months, median duration of event-free survival (EFS) and overall survival (OS) are 21 and 57 months, with 24% and 48% probabilities of being event-free and alive after 6 years, respectively. Among the group of 39 responders, CR was significantly associated with prolonged response and survival (2 deaths and 6 relapses/16 patients) as compared with PR (11 deaths and 15 relapses/23 patients), and remained the only significant variable also in a multivariate analysis. Myelosuppression did not protract beyond one week in transplanted patients; extra-hematologic toxicity was very low.

INTERPRETATION AND CONCLUSIONS

This multicenter study confirms the feasibility of an aggressive approach to de novo MM patients. Additional confirmation is given of the increased rate of CR, and the significant prolonged survival observed in complete responders. In this experience the association melphalan plus busulfan was shown to be effective, at least as part of conditioning regimens, in the transplant strategy.

Enumeration of CD34+ hematopoietic progenitor cells for clinical transplantation: comparison of three different methods

Three different methods for determination of CD34+ cells in G-CSF-mobilized peripheral blood were compared. The methods were: the Milan/Mulhouse protocol, the ISHAGE guidelines for CD34+ cells enumeration and our own protocol. The procedure we have adopted is essentially a Milan/Mulhouse protocol-derived methodology combined with a multiparametric approach using the PAINT-A-GATE software analysis program. The samples were collected from 70 patients affected by acute leukemia, non-Hodgkin's lymphoma, Hodgkin's lymphoma, myeloma and breast cancer who were scheduled to receive autologous PBSC transplantation. PBSC collection was performed following mobilization with subcutaneous G-CSF at 5-10 microg/kg/day. A minimum target of 2 x 10(6)/kg CD34+ cells was considered an acceptable harvest to ensure a safe transplant. On average, three aphereses per patient were performed and a total of 204 apheresis samples were analyzed. Regression analysis of the percentage and absolute number of CD34+ cells, as calculated with each method, achieved an excellent correlation in spite of methodological differences. In fact, both CD34+dim and CD34+CD45- events were included in our gating strategy. In the setting of a triple staining associating CD34, CD38 and CD45, we identified a variable fraction of CD34+CD38+CD45- cells which would be otherwise undetected due to its CD45 negativity. To this end, we used a new technology referred to as laser-scanning cytometry (LSC) which allowed the isolation and morphological identification of CD34+CD45- cells. By comparing CD34+CD45+ and CD34+CD45- cells, we found that they share a common morphology, thus confirming the hypothesis that the latter are to be considered for CD34+ cell calculation. The median number of CD34+ cells/kg, as calculated by the three methods, was: 4.79 x 10(6)/kg (range 1-570) for the Milan/Mulhouse protocol, 3.9 x 10(6)/kg (range 0.8-498) for the ISHAGE one, and 5.17 x 10(6)/kg (range 2-599) for our protocol. The median time to ANC and PLT engraftment was 11 (range 9-24) and 20 (range 10-70) days, respectively. Our protocol achieved the best correlation between CD34+ cells/kg and time to ANC/PLT recovery according to the Spearman's rank test (r = -40 and P < 0. 015 for ANC, r= -46 and P = 0.005 for PLT). We conclude that (1) CD45 does not appear the ideal partner of HPCA-2 for determination of hematopoietic progenitors in mobilized peripheral blood; and (2) for clinical application, a single staining with 8G12 appears simple, reliable and feasible when rigorous procedures for sample preparation and acquisition are followed and an adequate software for multiparametric analysis is available.

Red blood cell depletion of cord blood using hydroxyethylstarch double sedimentation: analysis of 40 cases

Cord blood has been shown to successfully reconstitute haematopoiesis following allogeneic transplantation in a variety of disorders. A major drawback of cord blood has been the risk of transfusion reaction secondary to ABO incompatibility and reduction in the stem cell pool if cord blood is manipulated to remove red cells. We report our experience on red blood cell depletion of cord blood (CB) with hydroxyethylstarch (HES) double sedimentation. The nucleated and mononucleated cell recovery passed from 78.4% at 90 min to 92.9% at 180 min and from 85% at 90 min to 96% at 180 min, respectively. The overall recovery of CCD34+ cells and of haemopoietic progenitors (CFU-GM) was 90.5% and 83.8%, respectively. The data indicate that HES double sedimentation is a simple and effective technique for cord blood manipulation, but further studies are necessary to evaluate the clonogenic progenitor recovery after thawing.

Multiparametric analysis for the enumeration of CD34+ cells from bone marrow and stimulated peripheral blood

Determination of CD34+ cells was performed in bone marrow and G-CSF mobilised peripheral blood samples. We adopted three different protocols of analysis: the Milan/Mulhouse protocol, the ISHAGE guidelines for CD34+ cell determination and our own protocol based upon the use of PAINT-A-GATEPRO software analysis program. An excellent correlation was demonstrated between the three methods (r2 0.98); however the analysis of variance showed a statistically significant difference between the results generated with the three methods (P=0.001). The differences between the three procedures are discussed with a special focus on the value of CD34+dim cells and the role of CD45 in the setting of a double staining. We have in fact identified a minor subset (CD34+CD38+CD45-) which would go unrecognised based upon its CD45 negativity.

In vitro down-regulation of bcl-2 expression by all-trans retinoic acid in AML blasts

Using flow cytometry, we have investigated the effects of 0.5 microM all-trans-retinoic acid (ATRA) on bcl-2 expression in the blast cells of 25 acute myeloblastic leukemia (AML) patients and the HL-60 cell line after incubation for 6 days. We observed a significant decrease of bcl-2 expression after treatment with ATRA in 12 of 25 AML samples and the HL-60 cells. The mean fluorescence intensity (MFI) ratio for the bcl-2 levels of the ATRA responders (n = 12) was reduced to 7.9 +/- 4.8 following incubation with ATRA compared with 10.9 +/- 6.5 (mean +/- SD) for control samples incubated without ATRA (p = 0.011). There was no significant difference between the baseline bcl-2 MFI ratio in the ATRA responders (11.14 +/- 7, n = 12) and the non responders (14.18 +/- 11.3, n = 13; p = 0.432). The down-regulation of bcl-2 expression by ATRA was not significantly associated with CD34-negative or -positive AML. There was no correlation between AML subtypes and regulation of bcl-2 expression by ATRA. Complete remission and overall survival were not significantly improved in bcl-2 down-regulated cases. Our data confirm that ATRA can down-regulate the bcl-2 expression in AML blasts. Because many chemotherapeutic agents also operate through the activation of programmed cell death and bcl-2 levels are positively associated with resistance to apoptosis, ATRA can be used in combination chemotherapy to increase the chemosensitivity of some patients with AML.

All-trans retinoic acid and low-dose cytosine arabinoside for the treatment of 'poor prognosis' acute myeloid leukemia

Thirty-three patients with 'poor prognosis' acute myeloid leukemia, no longer suitable for aggressive chemotherapy, were treated with daily oral all-trans retinoic acid (45 mg/m2) daily and subcutaneous cytosine arabinoside (20 mg standard dose twice a day, day 1 to 10, every 4 weeks). Seventeen patients were males and 16 females, the median age was 67 (range 39-82 years). Eleven patients were at onset of disease, 15 were refractory to previous conventional therapies, three were in first relapse and three in second relapse and one patient had a secondary AML. Seventeen patients had a bone marrow blast infiltration < 50% and 16 > or = 50%. A total of 16 (48%) patients entered complete remission; the rate of complete remission increased to 88% in those patients (n = 17) with < 50% blast infiltration at the time of entering the study. Seventeen patients (52%) were resistant. The difference in response to therapy, according to bone marrow blast percentage (< or > or = 50%), was statistically significant (P < 0.001). Median duration of complete remission was 34.4 weeks (range 6.4-62.8). Mild to moderate hematologic toxicity was the most common side-effect. In conclusion all-trans retinoic acid and low-dose cytosine arabinoside appears to be an effective regimen for inducing complete remission in 'poor prognosis' acute myeloid leukemia and patients with < 50% bone marrow infiltration are likely to represent the ideal target to receive this combination therapy.

Cisplatin increases sensitivity of human leukemic blasts to triazene compounds

High levels of O6-alkylguanine-DNA-alkyltransferase (OGAT) can, at least in part, account for tumor cell resistance to O6-alkylguanine alkylating agents, including triazene compounds. A pilot clinical study indicates that dacarbazine can induce a marked decrease of leukemic blasts in patients affected by acute myelogenous leukemia (AML) with low pretreatment levels of OGAT activity. In this study we show a synergistic antitumor effect between cisplatin (CDDP) and temozolomide (an in vitro active analog of dacarbazine), following combined in vitro treatment of leukemic blasts. Synergistic effect appears to be CDDP-dose dependent. In vivo treatment of leukemic patients with CDDP was followed by a reduction of OGAT activity in 2 out 3 cases. These data point out that CDDP could be a good candidate for depleting OGAT protein of leukemic cells, thus reversing tumor cell resistance to dacarbazine.

Treatment of multiple myeloma with autologous blood stem cell transplantation. Preliminary results of an Italian multicentric pilot study

Starting from May, 1991, 35 untreated myeloma patients entered a multicentric pilot study to evaluate the feasibility of a program of PBSC transplantation for previously untreated myeloma patients. The schedule was as follows: 2 cycles of VAD followed by CY, 7 g/mq+G-CSF (Granulokine, Roche) for 14 days, to increase and collect PBSC. The subsequent conditioning regimen was Melphalan+Busulfan followed by G-CSF. As maintenance R alpha-2 IFN was given, until relapse. The median follow-up is 14 months (4-22). On April 1993, 34 patients received at least 2 cycles of VAD, 27 were submitted to PBSC collection, 22 received conditioning regimen plus PBSC and 16 of them are in the maintenance treatment with IFN. Considering 28 patients for an intention to treat evaluation (35-7 in treatment), responding patients are 71% with 46% who achieved CR. White cells and platelets raised to > 1000/mmc and > 50,000/mmc after a median period of 10 and 13 days, from CY, and 11 and 14 days from transplant, respectively. Two patients relapsed, 2 others died while in PR because of CMV epatitis and candida pneumonia. The median number of CD34+ cells and CFU-GM was 24.75 x 10(6)/kg b.w. and 28.1 x 10(4)/kg b.w. respectively. In conclusion this treatment seems to be feasible and with low toxicity, but a longer follow-up is needed to evaluate the progression free survival of the high proportion of responding patients that we observed.

Mechanisms underlying T-lymphocyte activation: mitogen initiates and IL-2 amplifies the expression of transferrin receptors via intracellular iron level

Peripheral blood mononuclear cells (PBM) pulsed with lectin (PHA or Con A for 0.25-3 hr) show a low expression of interleukin-2 and transferrin receptors (IL-2Rs, TfRs) and a mild decline of intracellular ferritin level, compared to control cultures grown in continuous presence of mitogen. Interestingly, lectin-pulsed PBM do not release detectable amounts of IL-2 in the medium. Furthermore, expression of TfRs in these lymphocytes is not inhibited by addition of excess anti-IL-2 neutralizing monoclonal antibody, but is significantly inhibited by treatment with iron salts. These observations suggest that mitogen triggers an IL-2-independent expression of TfRs, at least in part via a decrease of intracellular iron level. Addition of either recombinant IL-2 (rIL-2) or an iron chelator (picolinic acid) to lectin-pulsed PBM induces both a marked enhancement of TfR synthesis and a sharp decline of intracellular ferritin level, which are comparable to the corresponding pattern observed in control cultures. Conversely, addition of iron salts fully inhibits the increase of TfR expression induced by rIL-2. These observations strongly suggest that the enhanced TfR synthesis elicited by rIL-2 is mediated by depletion of a regulatory intracellular iron pool. In line with these studies, greater than 99% purified T lymphocytes stimulated by lectin show a low expression of TfRs, which is markedly enhanced by addition of exogenous rIL-2. Altogether, we postulate that: (i) in resting T lymphocytes the gene encoding TfR is apparently in a 'closed' configuration; (ii) even in the absence of IL-2 activity, a mitogen pulse is sufficient to initiate the expression of TfRs, at least in part via a decline of intracellular iron level; and (iii) TfR synthesis is then largely amplified by IL-2, again via a decrease of the size of a regulatory intracellular iron pool.