Conditioning Regimen For Bone Marrow Transplantation Research Articles

Allogeneic Transplantation for High Risk Patients with Chronic Granulomatous Disease (CGD)

CGD is an immunodeficiency characterized by infections and inflammation, particularly inflammatory bowel disease (IBD) and lung inflammation, resulting from mutations in genes encoding any one of 5 subunits of the phagocyte NADPH oxidase impairing production of microbicidal oxidants. Bone marrow transplantation (BMT) has been shown to be curative of both the predilection for CGD-specific fungal and bacterial infections, and CGD related IBD, and is being offered more frequently to patients with appropriate donors, particularly in younger children with matched related donors. However, older adult patients with CGD, especially those with fungal infection not responding to conventional therapy, those with very severe IBD, and particularly those with inflammatory lung disease characterized by significant hypoxia are often considered ineligible for transplant by many US BMT centers. Furthermore, graft versus host disease (GvHD) and graft rejection following BMT of CGD patients going into the transplant with significant inflammation disease has been a significant problem. We report here the results to date of our ongoing protocol using Campath (1mg/kg divided over 4d), Busulfan (5mg/kg divided over 2d) and TBI (300cGy) combined with post-transplant cyclophosphamide (100mg/kg divided over 2d) and sirolimus for patients with CGD, with outcomes that appear to address these issues. Patients with C-reactive protein >100 were excluded from the standard criteria protocol because this had been shown to be a high mortality risk. However 6 patients whose CRP exceeded this exclusion criteria received exceptions to be treated 'off protocol' because of infections not responding to conventional therapy. Results: Number of patients to date: 30 plus 6 of whom were exceptions treated off protocol, and 1 retransplant; Follow up: 6 months to 5 years Donor types: 34 MUD, 3 MSD Patient Characteristics: Age: Mean 30/Range 6 to 57, Gender: 5F, 33M CGD type: GP91 (29, incl.1 lyonized female carrier), P47 (6), P67 (1), P22 (1) Transplant indications (some had more than one): Hypoxic inflammatory pulmonary disease (7), Colitis (11), Active infection (predominantly fungal) despite prolonged conventional therapy (14). See table Summary: Low dose Busulfan with TBI plus Campath and post-transplant cytoxan followed by sirolimus for BMT of CGD patients with CRP <100 at transplant is well tolerated, and results in improved engraftment rates with minimal GvHD. Patients with severe infections, hypoxic inflammatory lung disease, severe colitis and older age, but who have CRP<100 tolerate this conditioning regimen and benefit from the transplant with resolution of their underlying infection and/or non-infectious lung disease and/or severe IBD, even in patients who would not be considered eligible for transplant at other centers. This NIH non-myeloablative /immune suppressive BMT conditioning regimen not only significantly reduces incidence of graft failure and severe GVHD, but expands the group of CGD patients eligible for transplant to older patients and those with ongoing infection, hypoxic inflammatory lung disease, and/or severe IBD. These patients can be transplanted successfully and achieve cure of infection and/or significant improvement in their inflammatory pulmonary disease and IBD if a matched donor is available with this NIH CGD BMT conditioning regimen. Our studies confirm that patients with CRP>100 at transplant should not be transplanted and going forward are excluded without exception from this protocol. Also of note is that transplanted CGD patients have a high rate of fever, diarrhea and newly elevated CRP, but without hypoxia or hypotension, appearing to be a form of 'engraftment syndrome' that occurs starting at 10-12 days post transplant and resolving about the time that ANC >200-300. In 10 patients this was sufficiently severe to warrant treatment with tocilizumab 4mg/kg, which in all cases promptly resolved the fever. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Enhanced Expression of CXCR4 Facilitates the Trafficking of Anti-c-Kit Chimeric Antigen Receptor (CAR) T Cells to Bone Marrow and Achieves Effective Donor Stem Cell Engraftment

Allogeneic hematopoietic stem cell (HSC) transplantation is one of the curative therapeutic options for patients with a variety of inherited disorders of blood cells, including immune deficiencies and hemoglobinopathies. In addition, considerable progress has been made toward achieving clinical benefit from autologous HSC ex vivo gene therapy for some of these disorders. Generally, some level of conditioning using chemotherapy and/or radiation is needed to achieve the required engraftment of allogeneic HSC or gene corrected autologous HSC. There is considerable interest in finding less toxic and more focused approaches to achieve the conditioning. Promising results were observed using antibody-based approaches including anti-c-kit (CD117) or anti-CD45 which directly target HSCs, and these results can be enhanced by linking the antibody to a toxin such as saponin. Here, we explored a related approach in mouse models in which chimeric antigen receptor (CAR)-T cells targeting c-kit (c-kit CAR-T cells) were employed as conditioning to achieve significant engraftment of congenic HSCs. Our initial attempts at efficient conditioning with c-kit CAR-T cells failed because there was insufficient trafficking of CAR-T cells to bone marrow (BM) and insufficient CAR-T cell expansion in vivo and because we did not eliminate the CAR-T cells before transplanting congenic HSCs.To address these barriers, before injecting CAR-T cells (derived from C57BL/6 Thy1.1/CD45.2 mouse spleen on Day1 and transduced with CAR retrovirus on Day2) we pre-treated the recipient mice (Thy1.2/CD45.2) with low-dose cyclophosphamide (CY, 125 mg/kg; Day2) and co-transduced the c-kit CAR-T cells with a CXCR4 (CD184) expression vector (Day2), followed by injection of 5×106 CAR-T cells on Day3. We later removed these CAR-T cells by treating the mice with anti-Thy1.1 antibody (Ab) on Day11 prior to HSC transplantation from congenic Thy1.2/CD45.1 mice (Day12; 3×106 cells/mouse).After single CAR retrovirus transduction, >90% of T cells expressed CAR. When used in vitro, CAR-T cells efficiently depleted BM c-kit+ population (10.5% reduced to 1.6%) and completely suppressed colony formation in nitrocellulose medium. In initial in vivo studies, we used a luciferase marker in the CAR-T cells to allow whole body imaging in addition to flow cytometry (FACS) of BM to assess trafficking. With no pre-treatment of mice, both in vivo imaging and FACS demonstrated poor trafficking of CAR-T cells to BM (< 1% of cells), and there was no decrease of the BM c-kit+ population. In contrast, pre-treatment with low-dose CY and overexpression of CXCR4 on the CAR-T cell surface improved the CAR-T cell expansion in vivo and the migration into BM (mean Thy1.1+ cells, 11.9%; n= 5), and this was associated with significant in vivo depletion of BM c-kit+ population (9.0% reduced to 0.0%). Severe pancytopenia was confirmed in peripheral blood (Hgb 2.2 g/dL compared to the normal, 13.0 g/dL) along with aplastic BM (Figure A), and these mice died within 4 weeks without BM transplant. Subsequent injection of anti-Thy1.1 Ab completely depleted CAR-T cells in viv o. When congenic BM cells were transplanted into mice conditioned in this manner (CY+CAR-T+Thy1.1 Ab), these mice achieved complete recovery of hematopoiesis with significant engraftment of donor BM in all lineages in peripheral blood (Figure B) and long-term HSCs in BM (> 20 % donor chimerism).Our findings provide proof-of-concept that c-kit CAR-T cells can be used to achieve sufficient conditioning to allow donor chimerism after congenic transplantation without use of high-dose chemotherapy or radiation. Low-dose CY was required to achieve the reduction of host T cells and stimulate in vivo expansion of CAR-T cells. A key element to achieve BM HSC depletion was the co-transduction of CXCR4 that greatly increased trafficking of the CAR-T cells to BM. This finding may be one of the most important aspects of this study, with broader implications for the CAR-T cell field in suggesting that use of trafficking receptors or ligands might be generalizable as a method to enhance targeting to designated organs or solid tumors. In summary, our studies add to the list of tools that should be further explored in the effort to seek less toxic conditioning regimens for BM transplantation. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Choice of conditioning regimens for bone marrow transplantation in severe aplastic anemia

AbstractAllogeneic bone marrow transplantation (BMT) is curative therapy for the treatment of patients with severe aplastic anemia (SAA). However, several conditioning regimens can be used for BMT. We evaluated transplant conditioning regimens for BMT in SAA after HLA-matched sibling and unrelated donor BMT. For recipients of HLA-matched sibling donor transplantation (n = 955), fludarabine (Flu)/cyclophosphamide (Cy)/antithymocyte globulin (ATG) or Cy/ATG led to the best survival. The 5-year probabilities of survival with Flu/Cy/ATG, Cy/ATG, Cy ± Flu, and busulfan/Cy were 91%, 91%, 80%, and 84%, respectively (P = .001). For recipients of 8/8 and 7/8 HLA allele-matched unrelated donor transplantation (n = 409), there were no differences in survival between regimens. The 5-year probabilities of survival with Cy/ATG/total body irradiation 200 cGy, Flu/Cy/ATG/total body irradiation 200 cGy, Flu/Cy/ATG, and Cy/ATG were 77%, 80%, 75%, and 72%, respectively (P = .61). Rabbit-derived ATG compared with equine-derived ATG was associated with a lower risk of grade II to IV acute graft-versus-host disease (GVHD) (hazard ratio [HR], 0.39; P < .001) but not chronic GVHD. Independent of conditioning regimen, survival was lower in patients aged >30 years after HLA-matched sibling (HR, 2.74; P < .001) or unrelated donor (HR, 1.98; P = .001) transplantation. These data support Flu/Cy/ATG and Cy/ATG as optimal regimens for HLA-matched sibling BMT. Although survival after an unrelated donor BMT did not differ between regimens, use of rabbit-derived ATG may be preferred because of lower risks of acute GVHD.

HLA Class I Alloimmunization and Platelet Transfusion Support in HLA-Identical Bone Marrow Transplant for Sickle Cell Disease: A Sickle Transplant Alliance for Research Study

Introduction: HLA alloimmunziation has been described in patients, including pediatric patients with sickle cell disease (SCD), who received only leukocyte-reduced red blood cell (RBC) transfusions. While HLA alloimmunization has significant implications in bone marrow transplant (BMT) with an HLA-disparate donor (donor-specific HLA antibodies increase the risk of graft rejection), the clinical significance of this alloimmunization in HLA-identical BMT is unclear. In particular, it is unknown whether HLA class I alloimmunization affects platelet transfusion support during BMT. Platelet transfusions are especially important in BMT for SCD because of the historic high incidence of intracranial bleeding and the subsequent adoption of a relatively high platelet transfusion threshold.Methods: We tested for HLA class I alloimmunization using pre-BMT serum or plasma from 32 pediatric patients with SCD undergoing BMT with an HLA-identical sibling donor. HLA class I alloimmunization was evaluated using the FlowPRA® (panel reactive antibody) screening test which detects IgG antibodies to the majority of HLA class I antigens. Pre-BMT, patients had received leukocyte-reduced RBC transfusions. All patients undergoing BMT received leukocyte-reduced, irradiated, apheresis platelet transfusions to maintain a platelet count greater than 50 x 109/L. The number of platelet transfusions received in the first 45 days post-BMT was compared between those with a positive PRA versus those with a negative PRA using a two-sample t-test.Results: Among the 32 patients studied, the mean age at BMT was 9.4 years (range 1-21 years). Pre-BMT, 40% had received greater than 10 RBC transfusions and 32% of the entire cohort was receiving chronic RBC transfusions. BMT conditioning regimens included: traditional myeloablative busulfan, cyclophosphamide, antithymocyte globulin (BU-CY-ATG) (n=10); dose-reduced BU-CY-ATG + fludarabine (flu) (n=16); reduced intensity conditioning (RIC) alemtuzumab, flu, melphalan +/- thiotepa (n=5); and RIC BU-flu-ATG (n=1). All patients received HLA-identical sibling donor bone marrow, with 3 patients receiving a combined bone marrow and cord blood graft. All patients engrafted with 100% survival at day +45. Six patients developed acute graft-versus-host disease (GVHD): 1 grade I, 3 grade II, 1 grade 3, 1 grade 4. No patient had an intracranial bleed or other serious bleeding.From testing of the pre-BMT sample, 11/32 (34%) of patients had a positive HLA class I antibody screen. HLA class I alloimmunized patients received significantly more platelet transfusions than non-alloimmunized patients: mean 19.2 (SD 13.9) vs. 11.2 (SD 8.0) transfusions, p=0.049 (Figure). On univariate analysis, age, sex, conditioning regimen, and GVHD were each not significantly associated with the number of platelet transfusions (p>0.1). Only two patients developed hepatic sinusoidal obstruction syndrome (one HLA alloimmunized patient, one non-alloimmunized patient). Mean day of platelet engraftment was not significantly different between alloimmunized compared to non-alloimmunized patients: day +34.6 (SD 10.6) vs. day +30.2 (SD 11.3), p=0.28. Among HLA class I alloimmunized patients, the mean positive PRA was 19.7% (range 4-55%); there was no association with this PRA value and the number of platelet transfusions (r2=0.0064, p=0.81).Conclusion: In pediatric HLA-identical sibling BMT for SCD, pre-BMT HLA class I alloimmunization (but not the absolute PRA value) appears to be associated with more platelet transfusions. It is unclear if this increased platelet transfusion requirement is due directly to HLA antibody immune-mediated clearance of transfused platelets or other inherent differences of HLA class I alloimmunized patients. [Display omitted] DisclosuresQayed:Novartis: Consultancy.

Summary of the Third International Workshop on Clinical Tolerance.

The Third International Workshop on Clinical Tolerance was held in Stanford, California, September 8-9, 2017. This is a summary of Workshop presentations of clinical trials designed to withdraw or minimize immunosuppressive (IS) drugs in kidney and liver transplant patients without subsequent evidence of rejection. All clinical protocols had in common the use of donor or recipient cell therapy combined with organ transplantation. Tolerance to HLA matched and mismatched living donor kidney transplants with complete withdrawal of IS drugs without subsequent rejection for up to 14 years of observation was achieved in more than 50 patients enrolled in trials in four medical centers after the establishment of transient or persistent chimerism. Complete IS drug withdrawal without chimerism was reported in a prospective trial of liver transplantation combined with injection of regulatory T cells. IS drug minimization without rejection was reported in recipients of living donor kidney transplants enrolled in the One Study consortium after injection of recipient regulatory T cells, or injection of donor regulatory monocytes or dendritic cells. In conclusion, considerable progress has been made in achieving IS drug withdrawal after cell therapy in recipients of organ transplants.

Dose calculation with MCNPX code for Total Body Irradiation technique in sitting and lying postures

Total Body Irradiation (TBI) is a radiotherapy technique used to destroy malignant cells in bone marrow transplant conditioning regimens. The aim of this work was to estimate the equivalent and effective doses in TBI computational scenarios to analyze the changes in these quantities for different sources (cobalt-60 source and 6 MV photon beam), postures of the phantom, irradiation geometries, backscatter factors, and attenuators. The simulations were performed in MCNPX code using hybrid phantoms from the University of Florida. The simulation results showed uniform equivalent doses for the phantoms in the lying posture. It is also observed that when the phantoms are closer to a wall, there is an additional dose contribution of up to 6.55% to organs near to this structure. When the lead attenuators for the lungs are not present in exposure scenarios, the equivalent dose increases by more than 20%. For the effective dose, the values are considerably higher for the left lateral projection due to the greater energy absorption by more radiosensitive organs. The results of the simulations reaffirm the data found in the literature about TBI procedures.

Total body irradiation in allogeneic bone marrow transplantation conditioning regimens: A review.

Hematologic malignancies may require, at one point during their treatment, allogeneic bone marrow transplantation. Total body irradiation combined with chemotherapy or radiomimetic used in allogeneic bone marrow transplantation is known to be very toxic. Total body irradiation (TBI) induces immunosuppression to prevent the rejection of donor marrow. TBI is also used to eradicate malignant cells and is in sanctuary organs that are not reached by chemotherapy drugs. TBI has evolved since its introduction in the late fifties, but acute and late toxicities remain. Helical tomotherapy, which is widely used for some solid tumors, is a path for the improvement of outcomes and toxicities in TBI because of its sparing capacities. In this article, we first review the practical aspects of TBI with patient positioning, radiobiological considerations and total dose and fractionation prescriptions. Second, we review the use of intensity modulated radiation therapy in bone marrow transplantation with a focus on helical tomotherapy TBI, helical tomotherapy total marrow irradiation (TMI) and total marrow and lymphoid irradiation (TMLI) and their dosimetric and clinical outcomes. Finally, we review the perspective of dose escalation and the extension to older patients and patients with comorbidity who do not benefit from a standard bone marrow transplantation conditioning regimen.

Growth Velocity in Pediatric Bone Marrow Transplantation: Significance of Donor Type and Treatment Factors

Children who have undergone bone marrow transplantation (BMT) often have decreased growth. Growth is a multifactorial process, and the factors that influence growth after BMT are not completely understood. The authors hypothesized that donor type may be a factor influencing growth. Sixty-five children and adolescents who underwent BMT (32 related matched, 33 unrelated matched) were evaluated. Growth velocity (height standard deviation) was assessed prior to and 2 years following BMT. The results indicated that children and adolescents who underwent unrelated matched transplants had lower growth velocity (P < .059) than those with related matched transplants. Those who received the standard conditioning regimen that included total body irradiation (TBI) had a significantly lower growth velocity (P < .045) than those with chemotherapy-only regimens. Significant correlates of growth velocity included younger age at BMT and pre-BMT growth velocity. Thus, donor type, age at BMT, prior treatment, and BMT conditioning regimens that include TBI may all affect growth post-BMT. Careful monitoring of growth velocity is required for patients who have received an unrelated donor BMT.

Cold agglutinin disease (CAD)with autoimmune haemolytic anaemia: a case report of a coronary artery disease patient

Cold agglutinin disease (CAD) with autoimmune haemolytic anemia is characterized by the production of harmful cold autoantibodies associated with increased red cell destruction during exposure to cold. The treatment of CAD is very difficult and a great effort is required to obtain therapeutic success. Cyclophosphamide is a potent immunosuppressive agent which is widely used in all bone marrow transplantation conditioning regimens for patients with acquired severe aplastic anemia. In this report, we describe the case of a coronary artery disease patient with severe CAD, but without lymphoproliferative disease, in which general measures and immunosuppressive therapies were adopted, there by avoiding blood transfusions.

A 5-Year-Old Girl With Impaired Renal Function After Autologous Bone Marrow Transplantation

ONE MARROW TRANSPLANTATION(BMT) increasingly is used for the treatmentof patients with hematologic malignancies, somemetabolic and immunologic diseases, and de-pressed bone marrow after cancer treatment. Renalinsufficiency after BMT is common and related tomanycauses.Wepresentthecaseofagirlwhohadrenalinsufficiency4monthsafterautologousBMT.

Targeted Total Marrow Irradiation Using Three-Dimensional Image-Guided Tomographic Intensity-Modulated Radiation Therapy: An Alternative to Standard Total Body Irradiation

Total body irradiation (TBI) is an important part of bone marrow transplantation conditioning regimens. In TBI, dose escalation is difficult, because of associated normal organ toxicities. A method to deliver a more targeted dose of TBI preferentially to sites of greatest tumor burden is needed to reduce the dose to normal organs, reduce toxicities, and permit dose escalation. The purpose of this study was to evaluate, through a dosimetric analysis, the potential advantages and feasibility of selectively delivering targeted myeloablative doses of radiation to bone and marrow using a recently developed image-guided tomographic intensity-modulated radiation therapy delivery system (helical tomotherapy). Whole-body computed tomography datasets from 3 patients, age 5, 20, and 53 years, were used for treatment planning studies to evaluate 2 targeted TBI strategies: total marrow irradiation (TMI), in which the target region was defined as the skeletal bone, and total marrow and lymphoid irradiation (TMLI), in which the target regions were defined as bone, major lymph node chains, liver, spleen, and sanctuary sites, such as brain. Organ doses and dose distributions were compared with those in conventional TBI. A 1.7- to 7.5-fold reduction in median organ doses was observed with TMI and TMLI compared with conventional TBI. With this more targeted approach, a dose-volume histogram analysis predicted the potential to escalate the dose to bone (and containing marrow) up to 20 Gy, while maintaining doses to normal organs at lower levels than in conventional TBI to 12 Gy. Results were similar for the adult and pediatric patients, indicating that this form of targeted TBI will be applicable to most patients regardless of frame size. TMI to 10 Gy was delivered as part of a tandem transplant regimen to the 53-year-old patient with multiple myeloma. Clinical results confirmed the treatment planning predictions. After TMI, the patient experienced the expected blood count nadir, followed by successful engraftment. Grade 2 nausea and grade 1 emesis occurred only briefly on day 2 of TMI. Skin erythema, oral mucositis, esophagitis, and enteritis were not observed. This report demonstrates the feasibility and potential dosimetric advantages of selectively delivering myeloablative doses of radiation to bone and marrow using an image-guided tomographic intensity-modulated radiation therapy delivery system. Organ doses are substantially lower than those associated with standard TBI and predict the potential to significantly reduce associated toxicities and allow for dose escalation. The results also suggest that this form of targeted TBI may have potential advantages over other forms of targeted TBI, such as radioimmunotherapy or bone-seeking radionuclide therapy. Ongoing clinical trials will define the maximum TMI and TMLI doses achievable and define the potential advantages and limitations of this new approach for patients undergoing hematopoietic stem cell transplantation.

Dose response and factors related to interstitial pneumonitis after bone marrow transplant

Total body irradiation (TBI) and chemotherapy are common components of conditioning regimens for bone marrow transplantation. Interstitial pneumonitis (IP) is a known regimen-related complication. Using published data of IP in a multivariate logistic regression, this study sought to identify the parameters in the bone marrow transplantation conditioning regimen that were significantly associated with IP and to establish a radiation dose-response function. A retrospective review was conducted of articles that reported IP incidence along with lung dose, fractionation, dose rate, and chemotherapy regimen. In the final analysis, 20 articles (n = 1090 patients), consisting of 26 distinct TBI/chemotherapy regimens, were included in the analysis. Multivariate logistic regression was performed to determine dosimetric and chemotherapeutic factors that influenced the incidence of IP. A logistic model was generated from patients receiving daily fractions of radiation. In this model, lung dose, cyclophosphamide dose, and the addition of busulfan were significantly associated with IP. An incidence of 3%-4% with chemotherapy-only conditioning regimens is estimated from the models. The alpha/beta value of the linear-quadratic model was estimated to be 2.8 Gy. The dose eliciting a 50% incidence, D50, for IP after 120 mg/kg of cyclophosphamide was 8.8 Gy; in the absence of chemotherapy, the estimated D50 is 10.6 Gy. No dose rate effect was observed. The use of busulfan as a substitute for radiation is equivalent to treating with 14.8 Gy in 4 fractions with 50% transmission blocks shielding the lung. The logistic regression failed to find a model that adequately fit the multiple-fraction-per-day data. Dose responses for both lung radiation dose and cyclophosphamide dose were identified. A conditioning regimen of 12 Gy TBI in 6 daily fractions induces an IP incidence of about 11% in the absence of lung shielding. Shielding the lung to receive 50% of this dose lowers the estimated incidence to about 2.3%. Because the lungs can be adequately shielded, we recommend against using busulfan as a substitute for fractionated TBI with cyclophosphamide.

Fludarabine-based conditioning for allogeneic stem cell transplantation for multiply transfused patients with Fanconi's anemia

A fludarabine-based protocol (fludarabine (25 mg/m(2)/day x 6 days), cyclophosphamide (10 mg/kg/day x 2 days) and ATG (ATGAM 10 mg/kg/day x 4 days)) was used in four multiply transfused Fanconi's anemia (FA) patients aged 5-15 years to reduce rejection during allogeneic bone marrow transplantation (BMT). Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and mini methotrexate. The graft source was G-CSF-stimulated bone marrow or peripheral blood stem cells (PBSC) in two patients each. All patients engrafted with median time to ANC>500/mm(3) being 14 days (range: 12-17) and unsupported platelet count >20 ,000/mm(3) being 13 days (range: 11-18). One patient had secondary graft rejection on day 56 and expired on day 69 due to fungal pneumonia. One patient who developed acute myeloid leukemia on day 56 underwent successful induction with cytosine and daunorubicin followed by peripheral blood stem cell (PBSC) rescue on day 70 and is presently in remission with complete donor chimerism and grade I GVHD. At a median follow-up of 13 months (range: 4-21), three patients (75%) are well with complete donor chimerism. Addition of fludarabine to the conditioning regimen for BMT in FA can provide additional immunosuppression for engraftment without increasing toxicity.

Differential damage and recovery of human mesenchymal stem cells after exposure to chemotherapeutic agents

Mesenchymal stem cells (MSCs) are an important cellular component of the bone marrow microenvironment for supporting haemopoiesis. However, their response to high-dose chemotherapy remains unknown. We assessed the acute direct effects of individual chemotherapeutic agents on human MSCs (hMSCs). Using an in vitro culture system, the chemosensitivity of hMSCs was determined by XTT (2,3-bis(2-methoxy-4-nitro-5-sulphophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide) assay in comparison with that of NB-4 cells, a leukaemic cell line, and normal peripheral blood mononuclear cells. The recovery of cell numbers following exposure to chemotherapeutic agents and chemotherapy-induced apoptosis of hMSCs were evaluated. Human MSCs were resistant to chemotherapeutic agents commonly used in bone marrow transplantation (BMT) (i.e. busulphan, cyclophosphamide and methotrexate). However, they were relatively sensitive to a panel of cytotoxic agents, such as paclitaxel, vincristine, etoposide and cytarabine. Furthermore, different recovery patterns were noted. There was sustained suppression in hMSCs following 3 d exposure to paclitaxel, cytarabine and etoposide. In contrast, significant recovery was seen in hMSCs treated with dexamethasone and vincristine respectively. Human MSCs have different patterns of response to a panel of chemotherapeutic agents commonly used in BMT or cancer therapy. Understanding this variation is important in optimizing conditioning regimens for BMT.

Busulfan and cyclophosphamide as a conditioning regimen for pediatric acute lymphoblastic leukemia patients undergoing bone marrow transplantation.

Bone marrow transplantation (BMT) has become the standard therapy for children with relapsed acute lymphoblastic leukemia. The authors report their experience with histocompatible BMT for 52 children with acute lymphoblastic leukemia conditioned with a non-total body irradiation (TBI) regimen using busulfan and cyclophosphamide (Bu/Cy). The efficacy and long-term toxicity of the Bu/Cy regimen were determined. Overall survival was 35%. One-year, 3-year, and 7-year event-free survival rates were 54%, 33%, and 23%, respectively. Of the 52 BMT recipients, 26 relapsed. Thirteen of the relapsed patients received a second BMT and three were surviving as of this writing. The most frequent cause of death was leukemia relapse. An initial remission duration of less than 18 months was a factor in decreasing the event-free survival. The Bu/Cy regimen was well tolerated, with minimal transplant-related mortality. Neurocognitive function was tested before BMT and 1 year after BMT. When 1-year posttransplant neurocognitive test scores were compared with pretransplant scores, there was no decrease. However, there was a significant decrease in the pretransplant neurocognitive test scores in BMT recipients compared with their normal siblings. The use of Bu/Cy as a conditioning regimen for BMT does not appear to affect posttransplant neurocognitive function. Other long-term side effects, such as endocrinopathies and secondary malignancies, were also minimal. These data show that the Bu/Cy regimen is well tolerated, but the overall survival rate remains low.

Fludarabine based conditioning regimen for allogeneic stem cell transplantation for multiply transfused patients with Fanconi’s anemia

A fludarabine-based protocol (fludarabine (25 mg/m/day × 6 days), cyclophosphamide (10 mg/kg/day × 2 days) and ATG (ATGAM 10 mg/kg/day × 4 days)) was used in four multiply transfused Fanconi's anemia (FA) patients aged 5-15 years to reduce rejection during allogeneic bone marrow transplantation (BMT). Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and mini methotrexate. The graft source was G-CSF-stimulated bone marrow or peripheral blood stem cells (PBSC) in two patients each. All patients engrafted with median time to ANC>500/mm being 14 days (range: 12-17) and unsupported platelet count >20 ,000/mm being 13 days (range: 11-18). One patient had secondary graft rejection on day 56 and expired on day 69 due to fungal pneumonia. One patient who developed acute myeloid leukemia on day 56 underwent successful induction with cytosine and daunorubicin followed by peripheral blood stem cell (PBSC) rescue on day 70 and is presently in remission with complete donor chimerism and grade I GVHD. At a median follow-up of 13 months (range: 4-21), three patients (75%) are well with complete donor chimerism. Addition of fludarabine to the conditioning regimen for BMT in FA can provide additional immunosuppression for engraftment without increasing toxicity.

Allogeneic reaction induces dendritic cell maturation through proinflammatory cytokine secretion.

A bone marrow transplantation conditioning regimen is known to activate host dendritic cells (DC), which then become able to initiate graft-versus-host disease (GVHD) by presenting alloantigens. In this article, the authors addressed whether the alloreaction could reciprocally maintain DC in an activation state through secretion of proinflammatory cytokines. Skin biopsy specimens from GVHD patients were analyzed for the presence of DC. Supernatants collected from primary major histocompatibility antigen (allogeneic mixed leukocyte reaction [MLR] supernatant [SN]) or secondary minor histocompatibility antigen-mismatched mixed lymphocyte reactions were used to culture cytokine-promoted immature (im) DC. DC phenotype, function, and migration were analyzed. Immunostaining from GVHD skin biopsy specimens showed a deficit of Langerhans cells (LC) in the epidermis but the presence of mature DC in the dermis. Because LC should have recovered in the epidermis by this time, the authors then addressed whether the allogeneic reaction could maintain DC in an activation and migratory state, through secretion of inflammatory cytokines. With this aim, cytokine-mediated imDC were exposed to alloMLR-SN for 2 days. The authors observed that DC increased their expression of CD80, CD86, CD40, and human leukocyte antigen (HLA)-DR and neoexpressed CD83, DC-LAMP/CD208, and CCR7. At the functional level, alloMLR-SN-treated DC lost their ability to capture dextran, improved their allostimulatory capacity, and migrated in response to macrophage inflammatory protein 3beta. Interestingly, SN collected from secondary HLA-identical but minor histocompatibility antigen-mismatched MLR induced almost equivalent DC phenotypic maturation. The authors' results show that the allogeneic reaction leads to maturation and migration of DC through proinflammatory cytokine secretion. This might contribute to the impairment of LC reconstitution in the skin of patients with GVHD.

Phase I study of escalating doses of low-dose-rate, locoregional irradiation preceding Cytoxan-TBI for patients with chemotherapy-resistant non-Hodgkin’s or Hodgkin’s lymphoma

Purpose In patients in whom bone marrow transplantation (BMT) fails, recurrence often occurs at sites known to have contained disease before initiating BMT. The purpose of this study was to find the maximal tolerable dose of locoregional irradiation (LRT) between 1000 and 2000 cGy that could be integrated with our Cytoxan-total body irradiation (TBI) BMT conditioning regimen in the treatment of lymphoma. Methods and materials Patients had Hodgkin’s or non-Hodgkin’s lymphoma in chemotherapy-refractory relapse. All patients received LRT to a maximum of three sets of fields encompassing either all current or all previously known sites of disease. Cytoxan-TBI consisted of cyclophosphamide 50 mg/kg daily for 4 days followed by TBI of 1200 cGy given in four fractions. Results Twenty-one patients were enrolled. Radiation Therapy Oncology Group Grade 3 in-field acute toxicity was observed in 1 patient at each dose level up to 1500 cGy and in 3 of 6 patients receiving 2000 cGy. Clinically evident late toxicities were limited to hypothyroidism and one second malignancy occurring outside the LRT fields. Conclusion Low-dose-rate, LRT with concurrent Cytoxan-TBI before BMT has acceptable rates of in-field toxicity for doses up to 1500 cGy in five fractions. This regimen safely permits the use of a total combined radiation dose of up to 2700 cGy during 2 weeks, with encouraging in-field response rates in treatment-refractory patients.

Cataract-free interval and severity of cataract after total body irradiation and bone marrow transplantation: influence of treatment parameters

Purpose: To determine prospectively the cataract-free interval (latency time) after total body irradiation (TBI) and bone marrow transplantation (BMT) and to assess accurately the final severity of the cataract. Methods and Materials: Ninety-three of the patients who received TBI as a part of their conditioning regimen for BMT between 1982 and 1995 were followed with respect to cataract formation. Included were only patients who had a follow-up period of at least 23 months. TBI was applied in one fraction of 8 Gy or two fractions of 5 or 6 Gy. Cataract-free period was assessed and in 56 patients, who could be followed until stabilization of the cataract had occurred, final severity of the cataract was determined using a classification system. With respect to final severity, two groups were analyzed: subclinical low-grade cataract and high-grade cataract. Cataract-free period and final severity were determined with respect to type of transplantation, TBI dose, and posttransplant variables such as graft versus host disease (GVHD) and steroid treatment. Results: Cataract incidence of the analyzed patients was 89%. Median time to develop a cataract was 58 months for autologous transplanted patients. For allogeneic transplanted patients treated or not treated with steroids, median times were 33 and 46 months, respectively. Final severity was not significantly different for autologous or allogeneic patients. In allogeneic patients, however, final severity was significantly different for patients who had or had not been treated with steroids for GVHD: 93% versus 35% high-grade cataract, respectively. Final severity was also different for patients receiving 1 × 8 or 2 × 5 Gy TBI, from patients receiving 2 × 6 Gy as conditioning therapy: 33% versus 79% high-grade cataract, respectively. The group of patients receiving 2 × 6 Gy comprised, however, more patients with steroid treatment for GVHD. So the high percentage of high-grade cataract in the 2 × 6 Gy group might also have been caused to a significant extent by steroid treatment. The percentage of patients with high-grade cataract was lower in allogeneic transplanted patients without steroid treatment for GVHD than in autologous transplanted patients: 35% versus 48%. An explanation for this could be pretransplant therapy containing high-dose steroids. Conclusions: After high-dose-rate TBI in one or two fractions, steroids for GVHD influence latency time of a cataract and are of great importance for the severity the cataract finally attains. Although a cataract will develop in all patients, a clinically important high-grade cataract is relatively infrequent in patients not treated with steroids. Pretransplant therapy might also influence final severity of cataract.

Marrow sensitization to 5-fluorouracil using the ligands for Flt-3 and c-Kit

In vivo administration of c-kit ligand (KL) expands early hemopoietic progenitors and stem cells and sensitizes clonogenic progenitors to 5-FU-mediated cell death. Studies were performed to determine whether the in vivo administration of Flk-2/Flt-3 ligand (FL) is also capable of sensitizing progenitors to 5-FU. Mice were treated with FL (100 μg/kg every 12 hours for a total of 3 doses), KL (50 μg/kg, same schedule) or both, either alone or in combination with 5-FU (a single 125 mg/kg injection 3 hours before the last dose of cytokine). Femurs and spleens were harvested 48 hours following the last dose of cytokine, and the total numbers of mononuclear cells and colony forming unit cells (CFU-C) per femur and spleen were determined. Statistically significant increases in the number of CFU-C per femur were observed in response to FL, KL and FL+KL. In the spleen, statistically significant increases in CFU-C were observed only with the FL+KL combination. 5-FU alone produced marked reductions in CFU-C both in the femur and in the spleen. In the femur, 5-FU-mediated reductions in CFU-C were enhanced 3- to 30-fold in the presence of concomitant KL, FL or KL+FL administration. Surprisingly, the combination of KL+FL was no more effective in sensitizing marrow CFU-C to 5-FU than was KL alone, suggesting that CFU-C that are capable of surviving the KL/5-FU combination cannot be driven into cell cycle by FL. The effects of concomitant cytokine/5-FU administration in the spleen contrasted sharply with those observed in the femur, as FL, KL and FL+KL all failed to enhance 5-FU-mediated reductions in CFU-C. The ability of FL+KL to stimulate CFU-C expansion in the spleen combined with the inability of this cytokine combination to augment 5-FU-mediated progenitor toxicity in the spleen supports the contention that cytokine-mobilized progenitors are not in cycle. FL’s capacity to specifically sensitize marrow to the effects of cytotoxic drugs may have applications in bone marrow transplant conditioning regimens.