Pharmacokinetic Analysis and Antiepileptic Activity of Tetra-Methylcyclopropane Analogues of Valpromide

Purpose. The described structure pharmacokinetic pharmacodynamic relationships (SPPR) study explored the utilization of tetramethylcyclopropane analogues of valpromide (VPD), or tetra-methylcyclopropane carboxamide derivatives of valproic acid (VPA) as new antiepileptics. Methods. The study was carried out by investigating the pharmacokinetics in dogs and pharmacodynamics (anticonvulsant activity and neurotoxicity) of the following three cyclopropane analogues of VPD: 2,2,3,3-tetramethylcyclopropane carboxamide (TMCD), N-methyl TMCD (M-TMCD) and N-[(2,2,3,3-tetramethylcyclopropyl)carbonyl]-glycinamide (TMC-GLD). Results. The three investigated compounds showed a good anticonvulsant profile in mice and rats due to the fact that they were metabolically stable VPD analogues which were not biotransformed to their non-active acid, 2,2,3,3-tetramethylcyclopropane carboxylic acid (TMCA). M-TMCD was metabolized to TMCD and TMC-GLD underwent partial biotransformation to its glycine analogue N-[(2,2,3,3-tetramethylcyclopropyl)carbonyl]-glycine (TMC-GLN). Unlike TMC-GLN, the above mentioned amides had low clearance and a relatively long half life. Conclusions. In contrast to VPD which is biotransformed to VPA, the aforementioned cyclopropane derivatives were found to be stable to amide-acid biotransformation. TMCD and M-TMCD show that cyclic analogues of VPD, like its aliphatic isomers, must have either two substitutions at the position to the carbonyl, such as in the case of TMCD, or a substitution in the and in the positions like in the VPD isomer, valnoctamide (VCD). This paper discusses the antiepileptic potential of tetramethylcyclopropane analogues of VPD which are in animal models more potent than VPA and may be non-teratogenic and non-hepatotoxic.     

Allogeneic cell-mediated immunotherapy of leukemia with immune donor lymphocytes to upregulate antitumor effects and downregulate antihost responses

Donor lymphocyte infusion mediates most effective graft- versus-leukemia (GVL) effects following induction of host-versus-graft tolerance by transplantation of donor stem cells. This study was designed to maximize GVL effects across both major (MHC) and minor (mHgs) histocompatibility barriers in recipients inoculated with murine B-cell leukemia (BCL1), using specifically immune donor lymphocytes. GVL effects were induced with donor spleen cells from mice immunized across MHC or mHgs barriers with BCL/1 cells or normal BALB/c spleen cells. Our data suggest that spleen cells from donor mice immunized against murine B-cell leukemia of BALB/c origin, or to a lesser extent against normal host alloantigens, induce better therapeutic GVL effects with less great-versus-host disease (GVHD) across both mHgs and MHC. The cytokine profile of effector cells inducing predominantly GVL effects with reduced GVHD across MHC and mHg barriers consisted preferentially of upregulated IFN-gamma, IL-2, IL-10 and IL-12 in donors, implying a Th-1 to Th-2 cytokine shift. We hypothesize that immunotherapy with immune donor lymphocytes sensitized in vivo or in vitro with allogeneic tumor cells or normal host cells together with allogeneic BMT may provide an effective approach for amplifying GVL effects, while reducing procedure-related morbidity and mortality due to uncontrolled GVHD.     

Fludarabine in combination with cyclophosphamide decreases incidence of GVHD and maintains effective graft-versus-leukemia effect after allogeneic stem cell transplantation in murine lymphocytic leukemia

Graft-versus-host disease (GVHD) is a severe disorder and despite therapeutic efforts to decrease its distressing clinical manifestations, treatment is still not optimal. Here we report the results of studies, in which the purine analogue, fludarabine phosphate, was used in an attempt to modify and decrease GVHD after stem cell transplantation, across major histocompatibility barriers for murine leukemia. B-cell leukemia (BCL-1) bearing (BALB/c x C57BL/6) F1 mice received two cycles of fludarabine (0.8 mg/kg) for 5 days every 2 weeks, followed by 400 mg/kg cyclophosphamide i.p. Animals were then transplanted with C57BL/6 precursor cells and the development of leukemia and extent of GVHD was monitored both clinically and histopathologically. In the fludarabine-treated group, only nine of 28 (32%) mice developed leukemia, compared to 25 of 33 (76%) of control animals (P=0.0006 ). Mice treated with fludarabine-containing regimens prior to transplantation also had much less GVHD both clinically and at autopsy, while graft-versus-leukemia appeared to be augmented in the same animals.     

Allogeneic stem cell transplantation from matched related and unrelated donors in thalassemia major patients using a reduced toxicity fludarabine-based regimen

The only radical cure for thalassemia major patients today is the replacement of the defective hematopoietic system by allogeneic stem cell transplantation (allo-SCT). The major obstacles for the application of allo-SCT even from matched family members have been the transplant-related morbidity and mortality and graft failure that is usually associated with the recurrence of the thalassemia hematopoiesis. The outcome of allo-SCT from HLA-identical family donors is largely dependent on the age of the recipient as well as on pretransplant parameters reflecting the degree of organ damage from iron overload. In this study we report our experience of allo-SCT from matched related and unrelated donors, using a reduced toxicity conditioning consisting of fludarabine, busulfan or more recently busulfex and antithymocyte globulin, in a cohort of 20 patients with thalassemia major. The regimen-related toxicity was minimal, while the incidence of acute grade II-IV and chronic GVHD was 25 and 25%, respectively. With a median follow-up period of 39 months (range: 5-112 months) the overall survival was 100%, while thalassemia-free survival was 80%. Although the results of our study look promising, larger cohorts of patients and prospective clinical trials are required to confirm the benefits of our approach as a possible better alternative to the existing protocols.     

Treatment of post-hematopoietic stem cell transplantation hemorrhagic cystitis with intravesicular sodium hyaluronate

Hemorrhagic cystitis (HC) is a well-known complication of HSCT. Its overall incidence has been reported to vary from 7-68%. The spectrum of clinical presentation varies from asymptomatic microhematuria to life-threatening bleeding. Sodium hyaluronate is a glycosaminoglycan present on the bladder mucosa, which serves as an important protective substance against uroepithelial damage. Preparations of this component have been shown to be effective in the treatment of interstitial cystitis. We report our experience in the treatment of post-transplant HC with intravesical instillation of sodium hyaluronate. Five out of the seven patients included in this study achieved complete response, while one patient had only partial response. Sodium hyaluronate administration was not associated with any local or systemic adverse effects. We consider that the results of our study are promising and the efficacy of sodium hyaluronate in the treatment of post-transplant HC should be tested in larger cohorts of patients.     

Examination of HER3 targeting in cancer using monoclonal antibodies

The human EGF receptor (HER/EGFR) family of receptor tyrosine kinases serves as a key target for cancer therapy. Specifically, EGFR and HER2 have been repeatedly targeted because of their genetic aberrations in tumors. The therapeutic potential of targeting HER3 has long been underestimated, due to relatively low expression in tumors and impaired kinase activity. Nevertheless, in addition to serving as a dimerization partner of EGFR and HER2, HER3 acts as a key player in tumor cells’ ability to acquire resistance to cancer drugs. In this study, we generated several monoclonal antibodies to HER3. Comparisons of their ability to degrade HER3, decrease downstream signaling, and inhibit growth of cultured cells, as well as recruit immune effector cells, selected an antibody that later emerged as the most potent inhibitor of pancreatic cancer cells grown as tumors in animals. Our data predict that anti-HER3 antibodies able to intercept autocrine and stroma–tumor interactions might strongly inhibit tumor growth, in analogy to the mechanism of action of anti-EGFR antibodies routinely used now to treat colorectal cancer patients.Growth factors and their plasma-membrane–embedded receptors regulate cellular proliferation and migration during both embryogenesis and oncogenesis (1). One example entails the epidermal growth factor (EGF) family and the corresponding human EGF receptor (HER)/ERBB family of four receptor tyrosine kinases: the EGF receptor (EGFR or ERBB1), HER2 (c-Neu or ERBB2), HER3 (ERBB3), and HER4 (ERBB4) (2). The intracellular parts of ERBB/HER receptors harbor a catalytic tyrosine kinase domain (3). After ligand binding to an ectodomain, these receptors form active homodimers or heterodimers (4–7). Unlike EGFR, HER3/ERBB3 presents very low tyrosine kinase activity (8). Nevertheless, it binds neuregulins (NRGs) and exerts profound influence on signaling pathways, primarily through dimerization with EGFR and HER2. In line with roles in cancer progression, and similarly to EGFR and HER2, mutant forms of HER3 have recently been reported in colon and gastric cancer (9).Cancer therapies that use monoclonal antibodies (mAbs) to target ERBB/HER family members are becoming a mainstay in oncology. For example, trastuzumab, which targets HER2, is currently used to treat gastric and breast cancer (10, 11). However, the majority of patients with metastatic HER2-positive breast cancer will become trastuzumab-resistant after prolonged treatment, a development significantly less common in an adjuvant or neo-adjuvant setting. It has been reported that trastuzumab-resistant tumors show elevated expression of HER3 (12), and, similarly, inhibition of HER2 using a kinase inhibitor also up-regulates HER3 (13). Likewise, HER3 has been implicated in the development of resistance to treatment with other ERBB/HER-targeted therapies (14, 15), agents blocking insulin-like growth factor receptors (16), and chemotherapeutic agents (17). For these reasons, anti-HER3 antibodies (Abs) are being developed by several laboratories, and some have reached initial clinical trials.Importantly, anticancer mechanisms of therapeutic Abs are multifactorial and incompletely understood. The involvement of Ab-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity, as well as various cellular processes such as triggering of apoptosis, blocking angiogenesis, inhibiting tumor cell proliferation, interfering with signaling cascades, and accelerating receptor internalization, have been described (18). Our own studies proposed critical involvement of the endocytic system. In particular, combinations of two mutually noncompetitive Abs (Abs against different epitopes that do not cause steric hindrance) to EGFR (19) or to HER2 (20, 21) have been shown to accelerate receptor endocytosis and inhibit tumor growth, better than either Ab alone. Furthermore, a recently completed clinical trial that combined with chemotherapy two mutually noncompetitive anti-HER2 mAbs, for the treatment of HER2-positive breast cancer (22), confirmed the clinical benefit of combining noncompetitive mAbs.Anti-HER3 agents that are being developed or are in clinical trials show promising results, yet their efficacy might be viewed, in general, as variable and rather modest (23). Hence, it is imperative to develop new agents and resolve their molecular mechanisms of action. In this study, we generated in mice a relatively broad series of anti-HER3 mAbs and examined them for the ability to both degrade HER3 and decrease downstream signaling. The new mAbs displayed a variety of biochemical and biological attributes, such as binding affinity to HER3, ability to displace NRG and block downstream signals, sort HER3 for degradation, and recruit natural killer cells. Ultimately, the Abs were tested in vitro and in tumor-bearing animals for their ability to inhibit growth of cancer cells. We focus on an especially potent tumor-inhibitory Ab that can displace NRG, robustly sort HER3 for intracellular degradation, and also recruit immune effector cells.     

Effect of Linomide on adhesion molecules, TNF-alpha, nitrogen oxide, and cell adhesion

Linomide (quinoline-3-carboxamide) is an immunomodulator with anti-inflammatory effects in rodents with autoimmune diseases. Its mode of action still remains to be elucidated. We hypothesized that an investigation of T cell interactions with the extracellular matrix (ECM), composed of glycoproteins such as fibronectin (FN) and laminin (LN), might provide better understanding of their in vivo mode of action in extravascular inflammatory sites. We examined the effect of Linomide on T cell adhesion to intact ECM, and separately to LN, and FN, and on the release and production of tumor necrosis factor (TNFalpha) and nitrogen oxide (NO) in relation to adhesive molecules in non-obese diabetic (NOD) female spleen cells, focusing on intracellular adhesion molecule-1 (ICAM-1) and CD44. NOD female mice that developed spontaneous autoimmune insulitis, which destroys pancreatic islets and subsequently leads to insulin-deficient diabetes mellitus, were studied. Linomide, given in the drinking water or added to tissue cultures in vitro, inhibited the beta1 integrin-mediated adhesion of T cells to ECM, FN and LN, as well as the production and release of TNFalpha and NO, which play a major role in the induction and propagation of T cell-mediated insulitis. In addition, exposure of T cells to Linomide resulted in increased expression of CD44 and ICAM-1 molecules on spleen cells of Linomide-treated mice; such an increase in adhesion molecule expression may lead to more effective arrest of T cell migration in vivo. The regulation of T-cell adhesion, adhesion receptor expression, and inhibition of TNFalpha and NO secretion by Linomide may explain its beneficial role and provide a new tool for suppressing self-reactive T cell-dependent autoimmune diseases.     

Reviewing the potential utility of interleukin-7 as a promoter of thymopoiesis and immune recovery

The identification of interleukin-7 (IL-7) as a critical cytokine in early B- and T-cell development, combined with the discovery that it acts on mature T cells, opens new avenues for investigating the thymopoietic machinery and manipulation of the immune system. Initially, IL-7 was thought to be a growth factor in the context of the B-cell lineage in that it stimulates proliferation of early B-cell progenitors. However, it appears that this cytokine has a much broader field of activity within the network of signal transduction. Indeed, evidence exists to support the pivotal involvement of IL-7 in the gene rearrangement of the T-cell receptor repertoire that ultimately leads to thymocyte commitment. The finding that IL-7 is an inducer of both cytotoxic T-cell- and lymphocyte-activated killer cells is one of the significant recent developments in the field of tumor immunology. Lately, it has been demonstrated that administration of IL-7 to mice after myeloablative treatment accelerates immune recovery via a unique pathway. This review of the literature dealing with IL-7 in the realm of immune function shows, inter alia, the value of the cytokine in immunosuppressed animals. The collection of findings noted in this paper may be considered the forerunner for clinical application of IL-7 in a variety of conditions of hematolymphopoietic failure.     

Interleukin-7 induced facilitation of immunological reconstitution of sublethally irradiated mice following treatment with alloreactive spleen cells in a murine model of B-cell leukemia/lymphoma (BCL1)

Interleukin-7 (IL-7) plays a key role in maturation and function of both T and B cells. We investigate the potential use of recombinant human IL-7 for facilitation of graft-versus-leukemia (GVL) effects mediated by T cells following transplantation in a murine model. Administration of IL-7 in vivo to allogeneic-transplanted mice improved disease-free survival: 67% of mice treated with IL-7 remained alive and disease free for more than 60 days, in comparison to 17% of the controls (P<0.05). Similar results were obtained when C57BL/6 spleen cells sensitized against irradiated B-cell leukemia (BCL(1)) cells in the presence of IL-7 were transplanted to F(1) mice, followed by IL-7 treatment in vivo. Of the BALB/c mice that received spleen cells from F(1) mice treated with IL-7 following transplantation of C57BL/6 spleen cells sensitized with irradiated BCL(1) in the presence of IL-7, only 29% developed leukemia, as compared to 79% in the control group (P<0.05). Mice treated with IL-7 showed increased splenic and thymic cellularity and improved T cell-dependent proliferative responses compared to the controls (P<0.05). IL-7 may provide a novel tool to enhance immune reconstitution following transplantation of mismatched stem cells and for enhancement of GVL effects mediated by alloreactive lymphocytes.     

Alefacept treatment for refractory chronic extensive GVHD

Alefacept (Amevive) is an immunosuppressive dimeric fusion protein that is used for psoriasis control. We recently showed its effect in acute steroid-resistant/dependent GVHD. In this study, we describe the effect of alefacept treatment on chronic extensive GVHD (cGVHD). Twelve patients were included in this study; of these 8 (9 of 13 episodes) showed response. The median time to initial response was 2.25 weeks and the response was marked (n=3), moderate (n=2) or minimal (n=4). In two responding patients, the response was only temporary. Complications that appeared during treatment included infection, pericarditis and squamous cell carcinoma of the lip. All these events may be related to other drugs given simultaneously. With a 30-month median follow-up, 6 of 12 patients are alive, with all but one with stable or improved cGVHD. Six patients died because of GVHD progression, whereas none of the patients experienced relapse of the disease for which the transplantation was done. As reported earlier in psoriatic patients treated with alefacept, we found a consistent increase in the percentage of naive T cells as a consequence of treatment. In conclusion, alefacept is effective for the treatment of cGVHD, and dose and time intervals of treatment should be explored further.