Should rituximab replace splenectomy in the management of splenic marginal zone lymphoma?

BACKGROUND: SMZL is a relatively rare low grade B-cell lymphoma, characterized usually by an indolent clinical behavior. Since there is no prospective randomized trials to establish the best treatment approach, decision on therapeutic management should be based on the available retrospective series. Based on these data, rituximab and splenectomy appear to be the most effective. Splenectomy represented the standard treatment modality until early 2000s. More than 90% of the patients present quick amelioration of splenomegaly related symptoms along with improvement of cytopenias related to hypersplenism. The median progression free survival was 8.25 years in the largest series of patients published so far, while the median 5- and 10- year OS were 84% and 67%, respectively. Responses to splenectomy are not complete since extrasplenic disease persists. Patients with heavy bone marrow infiltration, lymphadenopathy or other disease localization besides the spleen are not good candidates for splenectomy. Furthermore splenectomy is a major surgical procedure accompanied by acute perioperative complications as well as late toxicities mainly due to infections. For that reasons splenectomy is not appropriate for elderly patients or patients with comorbidities with a high surgical risk. On the other hand rituximab monotherapy displays high efficacy with minimal toxicity. Several published series have shown an ORR more than 90%, with high CR rates (∼50%). The 10-year PFS and OS were 63% and 85%, respectively in a series of 104 SMZL patients. The role of rituximab maintenance has been investigated by only one group. Based on these data, maintenance with rituximab further improved the quality of responses by increasing significantly the CR rates (from 42% at the end of induction to 71% at the end of maintenance treatment), as well as the duration of responses: 7-year PFS was 75% for those patients who received maintenance vs 39% for those who did not (p < 0.0004). However no difference in OS has been noticed between the two groups, so far. Summarizing the above data, it is obvious that Rituximab monotherapy is associated with high response rates, long response duration and favorable safety profile, rendering it as the treatment of choice in SMZL.

Non-invasive MRI biomarkers for the early assessment of iron overload in a humanized mouse model of ß-thalassemia.

ß-thalassemia (ßT) is a genetic blood disorder causing profound and life threatening anemia. Current clinical management of ßT is a lifelong dependence on regular blood transfusions, a consequence of which is systemic iron overload leading to acute heart failure. Recent developments in gene and chelation therapy give hope of better prognosis for patients, but successful translation to clinical practice is hindered by the lack of thorough preclinical testing using representative animal models and clinically relevant quantitative biomarkers. Here we demonstrate a quantitative and non-invasive preclinical Magnetic Resonance Imaging (MRI) platform for the assessment of ßT in the γß0/γßA humanized mouse model of ßT. Changes in the quantitative MRI relaxation times as well as severe splenomegaly were observed in the heart, liver and spleen in ßT. These data showed high sensitivity to iron overload and a strong relationship between quantitative MRI relaxation times and hepatic iron content. Importantly these changes preceded the onset of iron overload cardiomyopathy, providing an early biomarker of disease progression. This work demonstrates that multiparametric MRI is a powerful tool for the assessment of preclinical ßT, providing sensitive and quantitative monitoring of tissue iron sequestration and cardiac dysfunction- parameters essential for the preclinical development of new therapeutics.

Chronic activation of mTOR complex 1 by branched chain amino acids and organ hypertrophy.

The mitochondrial branched chain aminotransferase-deficient mouse model (BCATm KO), which exhibits elevated plasma and tissue branched chain amino acids (BCAAs), was used to study the effect of BCAAs on mammalian target of rapamycin complex 1 (mTORC1) regulation of organ size. BCATm is the first enzyme in the BCAA catabolic pathway. BCATm KO mouse exhibited hypertrophy of heart, kidneys, and spleen. On the other hand, the mass of the gastrocnemius was reduced relative to body mass. Feeding the mice with a diet supplemented with rapamycin prevented the enlargement of the heart and spleen, suggesting that mTORC1 is the mediator of these effects. Consistently, enlargement of these organs was accompanied by the activation of mTORC1 complex as evidenced by enhanced levels of S6 and 4E-BP1 phosphorylation. HSP20, HSP27 and GAPDH were also increased in the heart but not gastrocnemius, consistent with mTORC1 activation. Liver, however, displayed no weight difference between the KO and the wild-type mice despite the highest activation level of mTORC1 complex. These observations suggest that the anabolic effect of mTORC1 activation at the organ level by BCAAs and inhibition by rapamycin are complex phenomenon and tissue-specific. In addition, it suggests that rapamycin can be used to counter hypertrophy of the organs when activation of mTORC1 is the underlying cause.

Curcumin may impair iron status when fed to mice for six months.

Curcumin has been shown to have many potentially health beneficial properties in vitro and in animal models with clinical studies on the toxicity of curcumin reporting no major side effects. However, curcumin may chelate dietary trace elements and could thus potentially exert adverse effects. Here, we investigated the effects of a 6 month dietary supplementation with 0.2% curcumin on iron, zinc, and copper status in C57BL/6J mice. Compared to non-supplemented control mice, we observed a significant reduction in iron, but not zinc and copper stores, in the liver and the spleen, as well as strongly suppressed liver hepcidin and ferritin expression in the curcumin-supplemented mice. The expression of the iron-importing transport proteins divalent metal transporter 1 and transferrin receptor 1 was induced, while hepatic and splenic inflammatory markers were not affected in the curcumin-fed mice. The mRNA expression of other putative target genes of curcumin, including the nuclear factor (erythroid-derived 2)-like 2 and haem oxygenase 1 did not differ between the groups. Most of the published animal trials with curcumin-feeding have not reported adverse effects on iron status or the spleen. However, it is possible that long-term curcumin supplementation and a Western-type diet may aggravate iron deficiency. Therefore, our findings show that further studies are needed to evaluate the effect of curcumin supplementation on iron status.

Molecular events in the activation of B cells and macrophages by a non-microbial TLR4 agonist, G1-4A from Tinospora cordifolia.

G1-4A, a polysaccharide from an Indian medicinal plant Tinospora cordifolia, was recently shown to protect mice against septic shock by modulating the proinflammatory cytokines. G1-4A also activated B cells polyclonally. The present report describes in detail the molecular events associated with G1-4A-induced immunomodulation in vitro and in vivo. G1-4A treatment led to an increase in the CD69 expression in lymphocytes. G1-4A-induced proliferation of B cells was completely inhibited by PI3K inhibitor Ly294002, mTOR inhibitor rapamycin and NF-kappaB inhibitor plumbagin. Akt, ERK and JNK were activated by G1-4A which finally resulted in the activation of IKK, degradation of IkappaB-alpha and translocation of NF-kappaB to the nucleus. Administration of G1-4A to mice led to splenomegaly and an increase in the numbers of T cells, B cells and macrophages. This increase in spleen cellularity was due to in vivo proliferation of lymphocytes and upregulation of anti-apoptotic genes. Anti-TLR4-MD2 complex antibody inhibited G1-4A-induced B cell proliferation and degradation of IkappaB-alpha suggesting that TLR-4 was a receptor for G1-4A on B cells. Activation of RAW 264.7 macrophages by G1-4A was found to be dependent on ERK and NF-kappaB-mediated signals. The phagocytosis index in peritoneal exudate cells (PEC) isolated from G1-4A treated mice was significantly higher as compared to that in PEC from control mice. G1-4A administration also increased the number of CD11b(+) cells in the PEC without an increase in the total number of PEC. Thus the present understanding of the molecular mechanism of action of G1-4A, a novel non-microbial TLR4 agonist, will pave the way for its application as an immunomodulator and adjuvant.

The mercapturic acid biotransformation pathway of hexachlorobenzene is not involved in the induction of splenomegaly, or skin and lung lesions in the Brown Norway rat.

Involvement of the mercapturic acid pathway in the induction of splenomegaly and skin and lung pathology by hexachlorobenzene (HCB) in the rat was investigated by seeking to determine whether pentachloronitrobenzene (PCNB) has the same inflammatory effects as HCB, since both compounds are directly conjugated to glutathione, and further processed into the same mercapturic acid metabolites which are excreted via the urine. Female Brown Norway (BN/SsNO1aHsd) rats at 3 to 4 weeks of age were orally exposed to diets with or without supplementation with 450 mg HCB or equimolar (467 mg) or higher (934 mg) amounts of PCNB per kilogram of diet over 4 weeks. Gross skin lesion development and body weight gains were assessed during exposure and spleen and liver weights as well as histopathologic changes in skin and lung were assessed after exposure. After 3 weeks of exposure, urinary metabolites of the mercapturic acid and oxidative biotransformation pathways were identified using high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS). Oral exposure of the rats to 450 mg/kg HCB resulted in an increase in relative spleen and liver weights as well as in the development of skin and lung pathology in the absence of overall liver toxicity. Equimolar or higher concentrations of PCNB caused none of these effects. Urinary levels of the mercapturic acid N-acetyl-S-(pentachlorophenyl)-cysteine (PCP-NAC), were comparable in HCB- and PCNB-treated rats. Levels of closely related methylsulfide derivatives of PCP-NAC, also generated via the same mercapturic acid pathway, appeared to be significantly higher in PCNB- than in HCB-treated rats, whereas the reverse was true for the urinary levels of the oxidative metabolite pentachlorophenol (PCP). Thus, results indicate that metabolites of the mercapturic acid pathway are not involved in the induction of splenomegaly and skin and lung pathology caused by HCB exposure in BN rats and that the main urinary metabolite of HCB in these BN rats is PCP. Since PCP itself, as well as other cytochrome P450-derived metabolites from HCB, are not likely to be involved in the induction of splenomegaly and skin and lung pathology, it is suggested that either the parent compound HCB or as-yet-unidentified non-P450-generated metabolites are involved in these inflammatory effects of HCB.