mycophenolic-acid and Lymphoma

Topics: Acute Disease; Adolescent; Adult; Aged; Allografts; Cord Blood Stem Cell Transplantation; Drug Monitoring; Female; Graft vs Host Disease; Humans; Immunosuppressive Agents; Leukemia; Lymphoma; Male; Middle Aged; Mycophenolic Acid

The study is a randomized phase II trial investigating graft-versus-host disease prophylaxis after non-myeloablative (90 mg/m(2) fludarabine and 2 Gy total body irradiation) human leukocyte antigen matched unrelated donor transplantation. Patients were randomized as follows: arm 1 - tacrolimus 180 days and mycophenolate mofetil 95 days (n=69); arm 2 - tacrolimus 150 days and mycophenolate mofetil 180 days (n=71); arm 3 - tacrolimus 150 days, mycophenolate mofetil 180 days and sirolimus 80 days (n=68). All patients had sustained engraftment. Grade II-IV acute graft-versus-host disease rates in the 3 arms were 64%, 48% and 47% at Day 150, respectively (arm 3 vs. arm 1 (hazard ratio 0.62; P=0.04). Owing to the decreased incidence of acute graft-versus-host disease, systemic steroid use was lower at Day 150 in arm 3 (32% vs. 55% in arm 1 and 49% in arm 2; overall P=0.009 by hazard ratio analysis). The Day 150 incidence of cytomegalovirus reactivation was lower in arm 3 (arm 1, 54%; arm 2, 47%; arm 3, 22%; overall P=0.002 by hazard ratio analysis). Non-relapse mortality was comparable in the three arms at two years (arm 1, 26%; arm 2, 23%; arm 3, 18%). Toxicity rates and other outcome measures were similar between the three arms. The addition of sirolimus to tacrolimus and mycophenolate mofetil is safe and associated with lower incidence of acute graft-versus-host disease and cytomegalovirus reactivation. (clinicaltrials.gov identifier: 00105001).

Topics: Adolescent; Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Female; Follow-Up Studies; Graft Rejection; Graft vs Host Disease; Hematopoietic Stem Cell Transplantation; Humans; Incidence; Leukemia; Lymphoma; Male; Middle Aged; Mycophenolic Acid; Recurrence; Sirolimus; Tacrolimus; Transplantation Chimera; Transplantation Conditioning; Transplantation, Homologous; Treatment Outcome; Unrelated Donors; Young Adult

This follow-up multicenter analysis is based on 362 pancreas allograft recipients at 14 institutions who were given tacrolimus between 1 May 1994 and 15 November 1995. Three groups were studied: (1) recipients given tacrolimus initially for induction and maintenance therapy (n = 250; 215 without, 35 with, a concurrent bone marrow transplant), (2) recipients who converted to tacrolimus for rescue or rejection therapy (n = 89), and (3) recipients who converted to tacrolimus for other reasons (n = 23). Of 215 recipients without a bone marrow transplant in the induction group, 166 (77%) underwent a simultaneous pancreas-kidney transplant (SPK), 29 (14%) a pancreas transplant alone (PTA), and 20 (9%) a pancreas after previous kidney transplant (PAK). Initial antibody therapy was given to 185 (86%) recipients. All 215 received tacrolimus and prednisone; 202 (94%) also received azathioprine (AZA) and 11 (5%) mycophenolate mofetil (MMF). The most common side effects of tacrolimus were neurotoxicity in 21%, nephrotoxicity in 21%, gastrointestinal (GI) toxicity in 13%, and diabetogenicity in 13% of these recipients. No recipient in this group developed new-onset insulin-dependent diabetes mellitus. Of 89 recipients in the rescue group, 71 (79%) had an SPK, 11 (13%) a PTA, and 7 (8%) a PAK. Before conversion, all had been on cyclosporine (CsA)-based immunosuppression; 74% of them had 2 or more rejection episodes previously. The most common side effects were nephrotoxicity in 27%, neurotoxicity in 26%, GI toxicity in 18%, and diabetogenicity in 8% of these recipients. No recipient in this group developed new-onset insulin-dependent diabetes mellitus. In the induction group patient survival at 1 yr was 98% for SPK, 79% for PTA, and 100% for PAK recipients. According to a matched-pair analysis, pancreas graft survival for SPK recipients at 1 yr was 88% with tacrolimus vs. 73% with CsA (p = 0.002); for PTA recipients, 68% vs. 70% (p > 0.35); and for PAK recipients, 85% vs. 65% (p = 0.13). Graft loss from rejection was not different with tacrolimus vs. CsA in all 3 pancreas recipient categories. At 1 yr, 17% of recipients had converted from tacrolimus to CsA for diabetogenicity, nephrotoxicity, or rejection; 23% had converted from AZA to MMF. The incidence of post-transplant lymphoma was < 2%. In the rescue group, patient survival rates at 1 yr were 96% for SPK, 100% for PTA, and 86% for PAK recipients (p < 0.08). Pancreas graft survival at 1 yr was 89% for SPK, 58% for

Topics: Adult; Anti-Inflammatory Agents; Azathioprine; Bone Marrow Transplantation; Case-Control Studies; Cyclosporine; Diabetes Mellitus; Diabetes Mellitus, Type 1; Female; Follow-Up Studies; Gastrointestinal Diseases; Graft Rejection; Graft Survival; Humans; Immunosuppressive Agents; Incidence; Kidney Diseases; Kidney Transplantation; Lymphoma; Male; Muromonab-CD3; Mycophenolic Acid; Nervous System Diseases; Pancreas Transplantation; Prednisone; Prospective Studies; Randomized Controlled Trials as Topic; Survival Rate; Tacrolimus; Transplantation, Homologous

Posttransplant lymphoproliferative disorder (PTLD) occurs in 1% to 3% of adult renal transplant recipients (RTRs). PTLD has a heterogeneous presentation and is often associated with Epstein-Barr virus (EBV) and immunosuppression. We present a descriptive case series of 16 RTRs who demonstrate a variety of PTLD manifestations. Fifty-six percent received rabbit antithymocyte globulin induction, and 37.5% received basiliximab. Maintenance immunosuppression included glucocorticoids, tacrolimus, and mycophenolate mofetil. Median time from transplantation to PTLD diagnosis was 96.5 months. PTLD involved a single site in 44% of RTRs and multiple sites in 56%. PTLD was localized to the gastrointestinal tract in 9 RTRs, in lymph nodes in 9, central nervous system in 4, bone marrow in 3, skin in 3, lungs in 2, perinephric space in 2, mediastinum in 1, and native kidney in 1. PTLD was EBV positive in 8 RTRs, monomorphic/monoclonal in 14, and of B-cell lineage in 13. Three RTRs had T-cell PTLD. Immunosuppressive agents, except glucocorticoids, were discontinued at diagnosis. Treatment was chemotherapy either alone (in 14 RTRs) or in combination with radiation. Complete remission was achieved in 62.5% of RTRs. Renal dysfunction developed in 62.5% of RTRs, and 4 received dialysis. The overall mortality rate was 62.5%, with median time of death 6.5 months after diagnosis. PTLD that was EBV negative and had T-cell involvement presented with aggressive disease and a higher mortality. Clinicians should be aware of the various PTLD manifestations. Early diagnosis and a multidisciplinary approach to treatment is crucial for improved patient outcomes.

Topics: Adult; Epstein-Barr Virus Infections; Female; Herpesvirus 4, Human; Humans; Immunosuppression Therapy; Immunosuppressive Agents; Kidney Transplantation; Lymphoma; Lymphoproliferative Disorders; Male; Mycophenolic Acid; Postoperative Complications; Renal Dialysis; Tacrolimus; Treatment Outcome

Immunoglobulin replacement therapy is recommended in case of severe hypogammaglobulinemia after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the supposed increased risk of infection in case of hypogammaglobulinemia has not been confirmed in allo-HSCT. In this study, we assessed the relationship between the gamma globulin level and the risk of infection during the 100 days following the allo-HSCT.. We gathered the weekly laboratory tests from day 7 to day 100 of 76 allograft patients, giving a total of 1 044 tests. 130 infections were documented clinically, by imaging, or microbiologically.. Average gamma globulin levels between D-7 and D100 did not differ between patients with or without infection (642 ± 232 and 671 ± 246 mg/dL, respectively, P = .65). Gamma globulin level <400 mg/dl was not associated with the occurrence of infection between the test studied and the next one (aOR 1.33 [0.84-2.15], P = .24). The gamma globulin level was not predictive of bacterial or fungal infections (AUC 0.54 [95%CI: 0.47-0.61]) nor of viral reactivations (AUC 0.51 [95%CI: 0.43-0.60]).. This confirmed that the humoral deficiency is a minor part of the immune deficiency in the 100 days post-transplant. This questions the relevance of the indications of immunoglobulin substitution during this period.

Topics: Aged; Bacterial Infections; Cyclosporine; Female; gamma-Globulins; Graft vs Host Disease; Hematopoietic Stem Cell Transplantation; Humans; Immunoglobulins, Intravenous; Immunologic Deficiency Syndromes; Immunosuppressive Agents; Leukemia; Lymphoma; Male; Middle Aged; Mycophenolic Acid; Mycoses; Myeloablative Agonists; Myelodysplastic Syndromes; Opportunistic Infections; Prognosis; ROC Curve; Transplantation Conditioning; Transplantation, Homologous; Virus Activation

Recently, haploidentical transplantations have been performed with unmanipulated BM or PBSC. This approach is becoming more widely adopted with the use of PTCY. However, there is limited evidence about this approach in children. We present 15 children who received 16 haploidentical HSCT with unmanipulated BM or PBSC using PTCY for GVHD prophylaxis. Post-transplant CY(50 mg/kg IV) was given on the third and fifth day, and CsA or tacrolimus with MMF or MP was also used for GVHD prophylaxis. All patients engrafted at a median of 16 and 18 days for neutrophil and thrombocyte recovery, respectively. Grades II-III acute GVHD developed in seven patients, and mild chronic GVHD was found in two patients. Two patients died within the first 100 days due to sepsis (TRM 12.5%). Eleven patients are currently alive, with a median follow-up of 12 months (range 6-22 months). The 12-month OS and DFS were 75 ± 10.8% and 68.8 ± 11.6%, respectively. Our results with these high-risk patients are encouraging for haploidentical HSCT in pediatric patients. Future studies should continue to assess haploidentical HSCT, including comparison of other modalities, in a primary pediatric population.

Topics: Adolescent; Blood Platelets; Child; Child, Preschool; Cyclophosphamide; Cyclosporine; Female; Graft vs Host Disease; Hematopoietic Stem Cell Transplantation; Humans; Leukemia; Lymphoma; Male; Methylprednisolone; Mycophenolic Acid; Neutrophils; Retrospective Studies; Risk; Sepsis; Tacrolimus; Tissue Donors; Transplantation Conditioning

Progressive outer retinal necrosis syndrome (PORN) is a severe clinical variant of necrotizing herpetic chorioretinitis, which occurs almost exclusively in patients with advanced acquired immunodeficiency syndrome (AIDS). To date, only a few cases of PORN have been reported in patients, mostly among those who were immunocompromised. To our knowledge, only one case of PORN in a patient with systemic lupus erythematosus (SLE) has been described. We report the case of a 44-year old HIV-negative patient with lupus nephritis, whom was being treated by mycophenolate mophetil (MMF), arechin and prednisone. After 14 months of MMF therapy, the patient revealed PORN symptoms; and several months later, the patient developed Type B primary central nervous system lymphoma (PCNSL). PORN is usually compared to acute retinal necrosis (ARN) syndrome, because of having the same causative agent: varicella zoster virus (VZV). There are also some similarities in clinical findings. Our observation supports the hypothesis that PORN symptoms in HIV-negative patients can be an intermediate form between ARN and PORN, and can vary according to the patient's immune status.

Topics: Adult; Antiviral Agents; Central Nervous System Neoplasms; Chloroquine; Chorioretinitis; Fatal Outcome; Female; Herpes Zoster; Herpesvirus 3, Human; HIV Seronegativity; Humans; Lupus Erythematosus, Systemic; Lymphoma; Magnetic Resonance Imaging; Mycophenolic Acid; Prednisone; Retinal Necrosis Syndrome, Acute; Visual Acuity

Immunosuppression for solid organ transplantation increases lymphoproliferative disease risk. While central nervous system (CNS) involvement is more rare, we noticed an increase in primary CNS (PCNS) disease. To investigate a potential association with the immunosuppressive regimen we identified all post-transplant lymphoproliferative disease (PTLD) cases diagnosed over a 28-year period at our institution (174 total, 29 PCNS) and all similar cases recorded in a United Network for Organ Sharing-Organ Procurement and Transplant Network (UNOS-OPTN) datafile. While no PCNS cases were diagnosed at our institution between 1986 and 1997, they comprised 37% of PTLD cases diagnosed from 2011-2014. PCNS disease was more often associated with renal vs. other organ transplant, Epstein-Barr virus, large B-cell morphology and mycophenolate mofetil (MMF) as compared to PTLD that did not involve the CNS. Calcineurin inhibitors were protective against PCNS disease when given alone or in combination with MMF. A multivariate analysis of a larger UNOS-OPTN dataset confirmed these findings, where both MMF and lack of calcineurin inhibitor usage were independently associated with risk for development of PCNS PTLD. These findings have significant implications for the transplant community, particularly given the introduction of new regimens lacking calcineurin inhibitors. Further investigation into these associations is warranted.

Topics: Adult; Aged; B-Lymphocytes; Calcineurin Inhibitors; Central Nervous System; Databases, Factual; Female; Herpesvirus 4, Human; Humans; Immunosuppression Therapy; Immunosuppressive Agents; Kidney Transplantation; Lymphoma; Lymphoproliferative Disorders; Male; Middle Aged; Multivariate Analysis; Mycophenolic Acid; Odds Ratio; Organ Transplantation; Postoperative Complications; Regression Analysis; Retrospective Studies

We hypothesized that in patients with early post allogeneic transplantation toxicities, the omission of the 3rd dose of methotrexate with concomitant starting of MMF would favorably affect complications. We found a higher incidence of grade 2-4 acute GVHD in patients given two doses methotrexate and MMF (n=31) compared to those given three courses of methotrexate (n=70) (p=.004), while grade 3-4 was similar. Other transplantation outcomes, including overall regimen-related-toxicity, were comparable. We conclude that tailoring the GVHD prophylaxis regimen may decrease the early post transplantation complications, however this come at the extent of a higher incidence of non-severe acute GVHD.

Topics: Adult; Aged; Drug Administration Schedule; Drug Substitution; Female; Graft vs Host Disease; Hematopoietic Stem Cell Transplantation; Humans; Immunosuppressive Agents; Leukemia; Lymphoma; Male; Methotrexate; Middle Aged; Mycophenolic Acid; Survival Analysis; Transplantation Conditioning; Young Adult

Topics: Antibodies, Monoclonal, Murine-Derived; Antineoplastic Combined Chemotherapy Protocols; Bacteremia; Central Nervous System Neoplasms; Drug Administration Schedule; Female; Fever; Fungemia; Humans; Immunocompromised Host; Immunosuppressive Agents; Lupus Nephritis; Lymphoma; Methotrexate; Mycophenolic Acid; Neurotoxicity Syndromes; Neutropenia; Rituximab; Treatment Outcome; Young Adult

Post-transplantation lymphoproliferative disorders (PTLD) are a spectrum of diseases defined as polyclonal or monoclonal proliferations of lymphocytes which occur after solid organ transplants. In this study, we report our first experiences with PTLD following liver transplantation in Iran.. We retrospectively analyzed five cases of PTLD which followed liver transplantation among more than 550 liver transplants in our center. Of these, three were pediatric cases and two were adults. The underlying causes were tyrosinemia, autoimmune hepatitis, and progressive familial intrahepatic cholestasis (PFIC) in the three pediatric cases. HCV hepatitis was the primary cause for cirrhosis in one of the adults and the other adult was labeled as cryptogenic cirrhosis. All cases, except for one, developed PTLD during the first year following liver transplantation.. Patients were diagnosed as PTLD, B-cell, MALT and Hodgkin-like (according to the WHO classification of PTLD). The three pediatric patients died despite discontinuation of immunosuppressive drugs and chemotherapy. Fortunately both adult patients, until now, are still alive.. The incidence of PTLD in our center is lower than previous reports from other centers (0.9%), with a 60% mortality rate and worse prognosis in the pediatric age group.

Topics: Adolescent; Adult; Antineoplastic Agents, Hormonal; Antineoplastic Agents, Phytogenic; Child, Preschool; Cyclophosphamide; Cyclosporine; Fatal Outcome; Female; Herpesvirus 4, Human; Humans; Immunosuppression Therapy; Immunosuppressive Agents; Incidence; Infant; Iran; Liver Transplantation; Lymphoma; Male; Mycophenolic Acid; Prednisolone; Tacrolimus; Vincristine

The increasing frequency of malignant tumors developing during chronic immunosuppression is an important determinant of the long-term survival of organ transplanted patients. This problem can be solved only if we are aware of the special characteristics concerning our patients. The incidence and frequency of tumors occurring in kidney transplant recipients differ from those of the Hungarian population. The increased tumor risk resulting from chronic renal failure, increasing age of prospective kidney recipients and, in addition, the increasing frequency of tumors diagnosed in the early post-transplantation period emphasize the importance of regular oncological screening of patients on the waiting list. Early diagnosis and treatment of tumors and precancerous conditions are equally important in transplanted patients as well, and the tumor risk could be decreased by applying low dose immunosuppression and the preferential usage of immunosuppressive drugs with an oncologically favorable effect. The prognosis of post-transplantation tumors is poor, as they respond poorly to therapy. Lymphomas are of great importance because of their frequency. Different immunosuppressive regimens represent varying degrees of risk in lymphoma development. This risk is lower in the case of mycophenolic acid. The composition of immunosuppression is a major factor in treatment; an oncologically ideal compound would prevent organ rejection and, at the same time, would not counteract oncological therapy. We have shown that mycophenolic acid inhibits the proliferation of human B-cell non-Hodgkin lymphomas and induces apoptosis by activating the intrinsic pathway, both in vitro and in vivo. The favorable properties of mycophenolic acid suggest that it can provide the necessary immunoprotection for the transplanted organ and, given its anti-lymphoma effects, it may also prove useful in the therapy of lymphoma patients. It may also be helpful in the treatment of "traditional" lymphomas of the non-transplanted population, where the major cause of therapeutical failure is the development of apoptosis resistance. Mycophenolic acid, combined with other chemotherapeutical drugs, may enhance apoptosis in lymphoma cells. Our promising experimental results provide a basis for further, clinical studies.

Topics: Adult; Aged; Animals; Antibiotics, Antineoplastic; Female; Humans; Hungary; Immunosuppressive Agents; Kidney Transplantation; Lymphoma; Male; Middle Aged; Mycophenolic Acid; Organ Transplantation; Transplantation, Heterologous

Lymphoproliferative disorders are known to complicate immunosuppressive therapy and two cases of primary lymphoma of CNS (PCNSL) have previously been described in association with mycophenolate mofetil (MMF) treatment. We report the third case of PCNSL in a patient with lupus nephropathy while on MMF treatment. PCNSL may be seen more frequently considering the increased use of MMF in immunosuppressant responsive conditions.

Topics: Adult; Central Nervous System Neoplasms; Diffusion Magnetic Resonance Imaging; Fatal Outcome; Female; Humans; Immunosuppression Therapy; Immunosuppressive Agents; Lupus Erythematosus, Systemic; Lymphoma; Mycophenolic Acid

This large prospectively conducted observational cohort study examined the risk of lymphoma and other malignancies with mycophenolate mofetil (MMF) in de novo renal transplant recipients. A total of 6751 patients receiving MMF, and an equal number of matched controls receiving non-MMF-based immunosuppression, were identified from two large registries (Organ Procurement and Transplantation Network/United Network for Organ Sharing (OPTN/UNOS) and Collaborative Transplant Study (CTS)) and followed for 3 years. The primary endpoint was development of lymphoma. Secondary endpoints included development of any malignancy. There was no evidence of any increased risk of developing lymphoma or malignancy with MMF. The risk of developing lymphoma with MMF compared with the non-MMF cohort was not higher in either the CTS registry (relative risk (95% confidence interval); 0.4 (0.17-0.94)) or the OPTN/UNOS registry (1.04 (0.61-1.78)). In the MMF group, there was a trend toward a lower risk of malignancy in both registries (OPTN/UNOS 0.86 (0.69-1.07); CTS 0.79 (0.61-1.02)) and a significant increase in time to malignancy in the CTS dataset (p < 0.026). This study has demonstrated that MMF is not associated with an increased risk of lymphoma or other malignancies post-renal transplant, and may even be associated with a lower risk in some populations.

Topics: Adult; Cohort Studies; Female; Graft Rejection; Graft Survival; Humans; Immunosuppressive Agents; Incidence; Kidney Transplantation; Lymphoma; Male; Middle Aged; Mycophenolic Acid; Prospective Studies; Registries; Risk Factors

It is now well established that after conventional allogeneic hematopoietic stem-cell transplantation (HSCT), erythropoietic recovery is impaired because erythropoietin (Epo) production remains inadequate for prolonged periods of time. However, erythropoietic reconstitution after nonmyeloablative SCT (NMSCT) has never been characterized.. Twelve patients received a nonmyeloablative conditioning regimen consisting of 2 Gy total body irradiation (TBI) alone (n=6), 2 Gy TBI and fludarabine (n=3), or cyclophosphamide and fludarabine (n=3), followed by transplantation of allogeneic peripheral blood stem cells. Graft-versus-host-disease (GvHD) prophylaxis was carried out with mycophenolate mofetil (from day -1 to day 28) plus cyclosporine (from day -1 to day 120 or longer in case of chronic GvHD). Erythropoiesis was quantitated by soluble transferrin receptor (sTfR) levels, and the adequacy of Epo production was evaluated by the observed-to-predicted Epo ratio (O/P Epo).. Mean sTfR levels decreased following the conditioning regimen but remained well within the normal range throughout the posttransplant period. The O/P Epo ratio presented an initial surge quite similar to that observed after conventional conditioning. Thereafter, the O/P Epo ratio normalized rapidly, and Epo levels remained adequate during the whole observation period.. Contrarily to what is observed after myeloablative transplant, Epo levels remained adequate after NMSCT, resulting in normal erythropoiesis. These results suggest that the administration of erythropoietin therapy (rHuEpo) could be less effective after NMSCT than after conventional allogeneic transplant.

Topics: Adult; Cyclosporine; Erythropoiesis; Erythropoietin; Female; Graft Rejection; Hematopoietic Stem Cell Transplantation; Humans; Immunosuppressive Agents; Leukemia; Lymphoma; Male; Middle Aged; Mycophenolic Acid; Receptors, Transferrin; Recombinant Proteins; Transplantation Conditioning; Transplantation, Homologous

Although the kidney transplant program at this center has been active for the past 18 yr, five out of the seven cases of post-transplant lymphoma in kidney transplant patients were observed over the past 2 yr. During this period, we have shifted from cyclosporine to tacrolimus (FK506 or prograf) for maintenance immunosuppression and for rescue therapy. We have also introduced mycophenolate (RS-61443) and have continued an antibody induction regimen in the immediate postoperative period. FK506 is 50-100 times more potent than cyclosporine. We have reported a decreased incidence of rejection, improved graft survival, and a general optimalization of patient survival with these newer regimens. Nonetheless, five cases of post-transplant lymphoma out of 233 kidney transplants (2.1%) performed during this time period (December 1993 to December 1995) occurred between 3 months to 1 yr after the transplant. Four of the five patients are still alive between 12 and 24 months after the diagnosis of lymphoma was made. All were without evidence of ongoing disease. Three of the five have grafts with excellent function for longer than 18 months after transplantation, while one is marginal and one patient expired on dialysis. The third and fourth patients had severe rejection before the diagnosis of PTLD was made. While the occurrence of five cases of post-transplant lymphoma over a 2 yr period is alarming, this is still within the 2-4% incidence of post-transplant lymphoma that has been reported in the literature in kidney transplant patients. Our results probably reflect the increasing potency of our immunosuppressive protocols but do not show any increase in the aggressiveness of this entity of post-transplant lymphoma during the continued follow up.

Topics: Adolescent; Adult; Antibody Formation; Cause of Death; Child; Cyclosporine; Female; Follow-Up Studies; Graft Rejection; Graft Survival; Humans; Immunosuppressive Agents; IMP Dehydrogenase; Incidence; Kidney Transplantation; Lymphoma; Male; Mycophenolic Acid; Prodrugs; Renal Dialysis; Survival Rate; Tacrolimus

Topics: Animals; Cyclophosphamide; Cyclosporine; Graft Rejection; Graft Survival; Haplorhini; Immunosuppressive Agents; Kidney Transplantation; Liver Transplantation; Lymphoma; Mycophenolic Acid; Papio; Polyenes; Sirolimus; Transplantation, Heterologous

Cultured tumor cell lines, tumor xenografts grown in athymic nude mice, and a murine experimental metastasis model were used to assess the in vitro and in vivo anti-tumor activity of the potent IMP dehydrogenase (IMPDH) inhibitor, mycophenolic acid (MPA), and its morpholinoethyl ester pro-drug, mycophenolate mofetil (MM). The growth of all the cell lines tested was inhibited by MPA in vitro, with EC50 values ranging from less than 0.1 microM to 3.9 microM. Mice were monitored for s.c. tumor outgrowth in the case of human tumor xenograft models or survival time for the murine experimental metastasis model. Treatment with MM p.o. was started 24 hr after tumor challenge or after tumors became palpable. Treatment of athymic nude mice bearing A3.01 (T-lymphoblast), Molt-4 (T-cell leukemia), CaPan-2 (pancreatic adenocarcinoma), CaLu-3 (non-small-cell lung adenocarcinoma), LS174T and T84 (colon adenocarcinoma), and Daudi (B-cell lymphoma) human tumor xenografts with MM significantly inhibited s.c. tumor growth. Treatment of BALB/c mice with MM after i.v. injection of murine RAW117-H10 lymphoma cells in an experimental metastasis assay resulted in increased survival time for treated animals. No significant inhibitory effect on s.c. tumor outgrowth was seen with MM treatment of SK-Hep-1, a human hepatic endothelioma, or Hep-3B, a liver adenocarcinoma, at any of the doses tested.

Topics: Animals; Antineoplastic Agents; Cell Division; Disease Models, Animal; Drug Screening Assays, Antitumor; Female; Humans; IMP Dehydrogenase; Leukemia; Lymphoma; Mice; Mice, Inbred BALB C; Mice, Nude; Mycophenolic Acid; Neoplasm Metastasis; Neoplasm Transplantation; Neoplasms; Neoplasms, Experimental; Transplantation, Heterologous

We have studied the kinetics of guanine incorporation into DNA in mouse T-lymphoma (S-49) mutant cells [PNPase (purine-nucleoside phosphorylase)- and HGPRTase (hypoxanthine: guanine phosphoribosyltransferase)-deficient] that are incapable of converting dGuo (deoxyguanosine) to Gua (guanine) ribonucleotides. Of the two possible pathways for an exogenous guanine source to reach DNA, firstly: dGuo----dGMP----dGDP----dGTP and secondly: Gua----GMP----GDP----dGDP----dGTP only the second pathway was found to be functional in providing guanine for DNA replication, although deoxyguanosine readily produced toxic cellular dGTP levels via the first pathway. The functional guanine-nucleotide-precursor pools for DNA are rather small; further, the depletion of the small GMP pool, but not that of GDP, GTP and dGTP, correlated well with the inhibition of DNA synthesis by mycophenolic acid, an IMP dehydrogenase inhibitor. These results support the hypothesis that guanine-nucleotide incorporation into DNA is highly compartmentalized and that a small functional guanine-nucleotide pool, e.g., the GMP pool, may serve a crucial role in limiting the availability of DNA precursor substrate.

Topics: Animals; Cell Compartmentation; Chromatography, High Pressure Liquid; Chromatography, Ion Exchange; Deoxyguanosine; DNA; Guanine; In Vitro Techniques; Kinetics; Lymphoma; Mice; Mutation; Mycophenolic Acid; Nucleic Acid Precursors; RNA

Mycophenolic acid (MA) was demonstrated to be an effective inhibitor of the growth of the intracellular parasitic protozoan Eimeria tenella in tissue culture and guanine was shown to reverse this inhibition as expected for an inhibitor of IMP dehydrogenase (IMP:NAD+ oxidoreductase, EC 1.1.1.205). A high performance liquid chromatography study of the intracellular nucleotide pools labeled with [3H]hypoxanthine was carried out in host cells lacking hypoxanthine-guanine phosphoribosyltransferase, and the depletion of guanine nucleotides demonstrated that the intracellular parasite enzyme was being inhibited by the drug. Kinetic studies carried out on the enzyme derived from E. tenella oocysts demonstrated substrate inhibition by NAD and mycophenolic acid inhibition similar to that found for mammalian enzymes, but different from that for bacterial enzymes. The inhibition by mycophenolic acid was not time-dependent and was immediately reversed upon dilution. As found previously for other IMP dehydrogenases, an Ordered Bi-Bi mechanism prevails with IMP on first followed by NAD, NADH off first, and then XMP. The kinetic patterns are consistent with substrate inhibition at high concentrations of NAD due to the formation of an E X XMP X NAD complex. Uncompetitive inhibition by MA versus IMP, NAD, and K+ was found and this was interpreted as evidence for the formation of an E X XMP X MA complex. A speculative mechanism for the inhibition of the enzyme is offered which is consistent with the fact that E X XMP X MA readily forms, whereas E X IMP X MA does not.

Topics: Animals; Chromatography, High Pressure Liquid; Cricetinae; Cricetulus; Eimeria; Humans; Hypoxanthine Phosphoribosyltransferase; IMP Dehydrogenase; Ketone Oxidoreductases; Kinetics; Liver; Lymphoma; Models, Chemical; Mycophenolic Acid; NAD; Placenta; Rats; Sarcoma 180

The mechanism of the cellular toxicity of four inosinate dehydrogenase (IMP-DH) inhibitors with different antitumor and antiviral pharmacological profiles was investigated in mouse lymphoma (S-49) cell culture. Drug effects on cell growth, nucleotide pools, and DNA and RNA synthesis were measured in the presence and absence of guanine salvage supplies. Both guanine and guanosine were capable of bypassing the IMP-DH block, while they also demonstrated some growth-inhibitory effects when added alone in high concentrations. All four drugs reduced cellular guanosine triphosphate levels and caused secondary changes of the uridine, cytidine, and adenosine triphosphate pools that were similar among the four drugs. However, several drug effects in addition to IMP-DH inhibition were observed except with mycophenolic acid which may represent a pure IMP-DH inhibitor. Both tiazofurin and selenazofurin interfered with the uptake and/or metabolism of uridine and thymidine tracers; however, this effect appeared not to contribute to their cellular toxicity in vitro. Moreover, selenazofurin and tiazofurin impaired the utilization of exogenous guanine salvage supplies for DNA and RNA synthesis, and guanine was particularly ineffective in reversing the toxic effects of tiazofurin on cell growth. This finding is important in view of the available guanine salvage supplies in vivo. Since tiazofurin, selenazofurin, and their known metabolites failed to inhibit hypoxanthine-guanine-phosphoribosyl transferase, guanosine monophosphate kinase, and guanosine diphosphate kinase in cell extracts or permeabilized cells, these drugs may interfere with salvage transport across cellular membranes. The toxic effects of mycophenolic acid and ribavirin were similarly reversed by salvage supplies of up to 200 microM guanine, which suggests that ribavirin primarily acts as an IMP-DH inhibitor under these conditions. This result could explain the rather low antitumor efficacy of both mycophenolic acid and ribavirin in vivo. However, increasing the guanine salvage supply in the medium above 200 microM further reversed the toxic effects of mycophenolic acid to maximum rescue, while it increased the toxicity of ribavirin (300 microM). This finding suggests the presence of a toxic mechanism of ribavirin at higher concentrations that is dependent upon the presence of guanine supplies sufficient to fully overcome the IMP-DH inhibition. This study documents that each antimetabolite displays a unique s

Topics: Adenosine Triphosphate; Animals; Cell Division; Cells, Cultured; DNA, Neoplasm; Guanine; Guanylate Kinases; Hypoxanthine Phosphoribosyltransferase; IMP Dehydrogenase; Ketone Oxidoreductases; Lymphoma; Mice; Mycophenolic Acid; Nucleoside-Diphosphate Kinase; Nucleoside-Phosphate Kinase; Organoselenium Compounds; Ribavirin; Ribonucleosides; RNA, Neoplasm; Selenium; Tritium; Uridine

Topics: Animals; Cell Line; Deoxyguanine Nucleotides; Deoxyguanosine; DNA; Guanine; Lymphoma; Mice; Mutation; Mycophenolic Acid; Nucleic Acid Precursors; Purine-Nucleoside Phosphorylase; Ribonucleotide Reductases

These studies with wild-type and mutant cells defective in IMP dehydrogenase and the previous data with the adenylosuccinate synthetase-deficient cell line suggest that among the clinical population with dominantly inherited hyperuricemia, patients with partial deficiencies in these enzymes exist. It is hoped that these pharmacogenetic cell culture models for overproduction hyperuricemia will lead to the initiation of a search for hyperuricemia patients with either of these deficiencies. If such patients are found it may be possible to design chemotherapeutic regimens by which effectors (inhibitors) of purine synthesis might ameliorate the overproduction of purines by the de novo pathway.

Topics: Animals; Cell Line; Disease Models, Animal; Gout; Humans; IMP Dehydrogenase; Ketone Oxidoreductases; Lymphoma; Mice; Mutation; Mycophenolic Acid; Ribonucleotides; Uric Acid

Toxic guanine depletion was shown previously to result in a dramatic reduction of DNA synthesis, while toxic adenine depletion failed to affect DNA synthesis (M. B. Cohen and W. Sadée, Cancer Res., 43: 1587-1591, 1983). In this study, relative DNA synthesis rates were measured in mouse lymphoma S49 cells over 24 hr after drug exposure and were compared to cell growth curves. DNA synthesis inhibition by mycophenolic acid (guanine starvation) was achieved at lower drug concentrations than was the inhibition of cell growth. This result further supports the hypothesis (reference above) that guanine starvation specifically affects cells in S phase while it allows cells with full DNA complement to divide. In contrast, L-alanosine (adenine starvation) failed to affect DNA synthesis for at least 24 hr at a concentration that inhibits cell growth by 80%. The dramatically different effects of guanine and adenine starvation on DNA synthesis can thus be used to assess the magnitude of each when blocking early de novo purine biosynthesis by 6-methyl-mercaptopurine ribonucleoside (6- MMPR ). The results suggest that, although 6- MMPR effects primarily resemble those of guanine depletion, adenine starvation measurably contributes to the overall toxicity of 6- MMPR . Drug combination experiments with L-alanosine, mycophenolic acid, and 6- MMPR suggest that the basic mechanisms underlying the toxic effects of guanine and adenine starvation act synergistically.

Topics: Adenine; Adenosine; Alanine; Animals; Antimetabolites, Antineoplastic; Cell Division; DNA Replication; Guanine; Kinetics; Lymphoma; Methylthioinosine; Mice; Mycophenolic Acid

In order to elucidate the regulatory functions of purine enzymes on the rate of purine biosynthesis, two phenotypically distinct mutant cell lines with altered IMP dehydrogenase activities were isolated from mutagenized cultures of mouse T-lymphoma (S49) cells. A single clone, MYCO-1A, was isolated from wild type S49 cells plated in semisolid agarose containing 1 microM mycophenolic acid. The MYCO-1A cell line was remutagenized, and a clone resistant to 20 microM mycophenolic acid, MYCO-1A-20, was isolated and characterized. Assays of IMP dehydrogenase activity in extracts prepared from mutant cells indicated that the enzyme behaved as a single kinetic species and that the maximal velocity of the mutant enzyme activity is 10-15-fold greater than that obtained from wild type extracts. Altered apparent Km values for substrates and the lack of normal sensitivity to mycophenolic acid of the enzymes from mutant cells imply that the mutants have an alteration in a structural gene coding for IMP dehydrogenase. Measurements of intracellular nucleotides indicated that the mycophenolic acid-resistant clones contained elevated levels of GMP and GTP. Incubation of wild type cells with 1 microM mycophenolic acid caused a depletion of intracellular GTP and GMP levels, an increase in the concentration of IMP, an increase in the total rate of de novo purine synthesis, and a massive excretion of inosine into the culture medium. Similar effects were found for MYCO-1A cells incubated with 5 microM, but not 1 microM, mycophenolic acid. However, neither purine overproduction nor nucleotide pool perturbations were observed for MYCO-1A-20 cells incubated with 25 microM mycophenolic acid. These results suggest that a genetic defect in IMP dehydrogenase activity in humans might lead to excessive purine overproduction with subsequent hyperuricemia and gout.

Topics: Animals; Cell Line; Clone Cells; Drug Resistance; IMP Dehydrogenase; Ketone Oxidoreductases; Kinetics; Lymphoma; Mice; Mycophenolic Acid; Neoplasms, Experimental

Incubation of mouse T lymphoma (S-49) cells with the inosinate dehydrogenase inhibitor mycophenolic acid produced a depletion of both GTP and dGTP, and resulted in growth inhibition, partial reduction in RNA synthesis, and drastic inhibition of DNA synthesis. Similar results suggested to others that the depletion of dGTP is primarily responsible for toxicity. However, guanosine was as effective as deoxyguanosine at preventing mycophenolic acid toxicity although deoxyguanosine was more effective at elevating dGTP levels. Moreover, in hypoxanthine-guanine phosphoribosyltransferase-deficient mutants of S-49 (6MPR-3-3) deoxyguanosine was unable to prevent mycophenolic acid toxicity or to re-establish normal DNA synthesis, although it returned cellular dGTP but not GTP levels to normal. No other nucleotide levels changed in a way which could account for the toxicity. Incubation of cells with a combination of deoxyadenosine, deoxycytidine, and erythro-9-(2-hydroxy-3-nonyl)adenine produced a selective depletion of dGTP to levels similar to that produced by mycophenolic acid, but did not affect cell growth. Studies with cells synchronized by centrifugal elutriation show that the toxicity of mycophenolic acid is specific to the S-phase of the cell cycle. Addition of actinomycin D at a concentration that inhibited RNA synthesis increased the availability of GTP and re-established normal DNA synthesis in mycophenolic acid-treated S-49 cells. These results suggest that the depletion of GTP rather than that of dGTP produces toxic effects in S-49 cells and that GTP is required for DNA synthesis.

Topics: Animals; Cell Division; Cell Line; Deoxyguanine Nucleotides; DNA, Neoplasm; Guanosine Triphosphate; Hypoxanthine Phosphoribosyltransferase; Kinetics; Lymphoma; Mice; Mutation; Mycophenolic Acid; Neoplasms, Experimental

The conceptual framework which underlies many studies of purine and pyrimidine metabolism in intact cells has been critically evaluated. The model that is implicit in many such studies is the single, partially purified enzyme. This paper gives examples both of instances in which the extrapolation of results of enzymes studies to intact cells has been successful and of instances in which enzymes behave differently in the intact cell than in cell extracts. Pitfalls in the extrapolation of results of enzyme studies to intact cells concern (a) metabolic pathways, (b) intracellular enzyme activities, (c) enzyme regulation, and (d) intracellular metabolite concentrations. Examples are also given of situations in which perturbations in one aspect of purine or pyrimidine metabolism lead to changes in other aspects, often distant in the network of reactions.

Topics: Adenine Phosphoribosyltransferase; Animals; Lymphoma; Methotrexate; Mycophenolic Acid; Nucleotides; Phosphoribosyl Pyrophosphate; Purine Nucleotides; Purines; Pyrimidine Nucleotides; Pyrimidines; Ribose-Phosphate Pyrophosphokinase

Topics: Antimetabolites; Caffeine; Cell Division; Cells, Cultured; Deoxyadenosines; Drug Synergism; Hydroxyurea; In Vitro Techniques; Lymphoma; Methotrexate; Methylthioinosine; Mycophenolic Acid; Neoplasms, Experimental; Time Factors

Mycophenolic acid and virazole are inhibitors of inosinate dehydrogenase and produce growth inhibition and loss of viability in cultured murine lymphoma L5178Y cells. Treatment with 1 muM mycophenolic acid produced the following changes in concentrations of acid-soluble nucleotides: (a) guanosine triphosphate decreased to less than 10% of control within 2 hr; (b) uridine triphosphate and cytidine triphosphate concentrations increased markedly; (c) adenosine triphosphate did not change; (d) deoxyguanosine triphosphate decreased; and (e) thymidine triphosphate increased. DNA synthesis was inhibited by 90% within 2 hr, whereas the incorporation of adenosine into RNA and of leucine into protein were much less affected. Virazole (100 muM) produces similar effects. These biochemical effects of mycophenolic acid, as well as its effects on cell growth, can be prevented by addition of guanylate to the medium. Mycophenolic acid treatment also appears to cause breakdown of high-molecular-weight DNA.

Topics: Adenosine Triphosphate; Cell Division; Cells, Cultured; Cytosine Nucleotides; DNA, Neoplasm; Guanine Nucleotides; Guanosine Triphosphate; IMP Dehydrogenase; Lymphoma; Mycophenolic Acid; Neoplasm Proteins; Neoplasms, Experimental; Ribavirin; Ribonucleosides; RNA, Neoplasm; Thymine Nucleotides; Uracil Nucleotides