lactoferrin and Lymphoma--B-Cell

Antibody-dependent cellular cytotoxicity (ADCC) is one of the possible mechanisms of action of the chimeric CD20 monoclonal antibody IDEC-C2B8 (rituximab). As granulocyte-colony stimulating factor (G-CSF) greatly enhances the cytotoxicity of neutrophils in ADCC, the efficacy of rituximab might be enhanced by the addition of G-CSF. In a phase I/II clinical trial, we investigated the safety and efficacy of the combination of rituximab and G-CSF (5 microg/kg/day, administered for 3 days, starting 2 days before each infusion) in 26 relapsed low-grade lymphoma patients. Adverse events occurred in 25/26 patients and mainly consisted of (grade I/II) fever (29%) and allergic reactions (19%). In phases I and II (375 mg/m(2) rituximab+G-CSF), 19 patients were evaluable for efficacy. The response rate was 42% (8/19; 95% CI 20-67%), with 16% (3/19) complete remissions and 26% (5/19) partial remissions. The median duration of response was 18 months, the median time to progression was 24 months. We conclude that the combination of rituximab and G-CSF is well tolerated. Although the overall response rate seems comparable to that reported for rituximab monotherapy, remission duration in this pilot phase II study is remarkably long. Randomized comparison with rituximab monotherapy should substantiate this promising finding.

Topics: Adult; Aged; Antibodies, Monoclonal; Antibodies, Monoclonal, Murine-Derived; Antineoplastic Combined Chemotherapy Protocols; Dose-Response Relationship, Drug; Granulocyte Colony-Stimulating Factor; Humans; Lactoferrin; Leukocyte Elastase; Lymphoma, B-Cell; Middle Aged; Neutrophil Activation; Recurrence; Remission Induction; Rituximab

Cationic antimicrobial peptides such as bovine lactoferricin (LfcinB) constitute an important innate defense mechanism against many microbial pathogens. LfcinB also binds to and selectively kills human cancer cells via a mechanism that involves reactive oxygen species (ROS) generation and caspase activation. The antimicrobial core of LfcinB consists of only six amino acids (RRWQWR), referred to in this study as LfcinB6. Although free LfcinB6 is devoid of cytotoxic activity against cancer cells, we show here that adding a cell-penetrating hepta-arginine sequence via a glycine-glycine linker to LfcinB6 generates a peptide (MPLfcinB6) that is selectively cytotoxic for human T-leukemia and B-lymphoma cells. Flow cytometric analysis of propidium iodide and fluorescein isothiocyanate-dextran uptake by MPLfcinB6-treated cancer cells revealed extensive damage to the cell membrane, which was confirmed by scanning electron microscopy. MPLfcinB6-induced cytotoxicity was also associated with sequential ROS production and mitochondrial membrane permeabilization; however, neither ROS nor caspase activation caused by the loss of mitochondrial membrane integrity was essential for peptide-mediated cell death. We conclude that MPLfcinB6 selectively kills human T-leukemia and B-lymphoma cells by causing extensive and irreparable damage to the cell membrane.

Topics: Amino Acid Sequence; Animals; Antimicrobial Cationic Peptides; Cattle; Cell Line, Tumor; Cell Survival; Flow Cytometry; Humans; Lactoferrin; Leukemia; Lymphoma, B-Cell; Membrane Potential, Mitochondrial; Microscopy, Electron, Scanning; Reactive Oxygen Species

Although current treatments based on the use of B-cell-specific anti-CD20 monoclonal antibodies and aggressive combinatorial chemotherapy have improved the survival of patients suffering from B-cell non-Hodgkin's lymphoma (NHL), some individuals fail to respond to treatment and relapses remain common. New and more effective treatments for B-cell NHL are therefore required. Bovine lactoferricin (LfcinB) is a cationic antimicrobial peptide that is cytotoxic for several human tumor cell lines but does not harm healthy cells. Here we show that in vitro treatment with LfcinB caused Raji and Ramos human B-lymphoma cells to die by apoptosis, as indicated by DNA fragmentation, chromatin condensation, and nuclear disintegration. LfcinB killed B-lymphoma cells more efficiently at low serum concentrations and was inhibited in the presence of exogenous bovine serum albumin, suggesting partial neutralization of cationic LfcinB by anionic serum components. LfcinB-induced apoptosis in B-lymphoma cells was caspase-independent since caspase-3 activation was not detected by Western blotting and the general caspase inhibitor z-VAD-fmk did not prevent LfcinB-induced DNA fragmentation. Importantly, immune-deficient SCID/beige mice that were inoculated intravenously with Ramos B-lymphoma cells in order to model B-cell NHL exhibited extended survival following systemic administration of LfcinB, indicating that LfcinB warrants further investigation as a novel therapeutic agent for the possible treatment of B-cell NHL.

Topics: Amino Acid Sequence; Animals; Antimicrobial Cationic Peptides; Antineoplastic Agents; Apoptosis; Caspase 3; Cattle; Cell Line, Tumor; Culture Media; Humans; Lactoferrin; Lymphoma, B-Cell; Mice; Mice, SCID; Molecular Sequence Data; Neoplasm Transplantation; Serum Albumin, Bovine; Transplantation, Heterologous

Cationic antimicrobial peptides (CAPs) exhibit promising anticancer activities. In the present study, we have examined the in vivo antitumoral effects of a 9-mer peptide, LTX-302, which is derived from the CAP bovine lactoferricin (LfcinB). A20 B cell lymphomas of BALB/c origin were established by subcutaneous inoculation in syngeneic mice. Intratumoral LTX-302 injection resulted in tumor necrosis and infiltration of inflammatory cells followed by complete regression of the tumors in the majority of the animals. This effect was T cell dependent, since the intervention was inefficient in nude mice. Successfully treated mice were protected against rechallenge with A20 cells, but not against Meth A sarcoma cells. Tumor resistance could be adoptively transferred with spleen cells from LTX-302-treated mice. Resistance was abrogated by depletion of T lymphocytes, or either the CD4(+) or CD8(+) T cell subsets. Taken together, these data suggest that LTX-302 treatment induced long-term, specific cellular immunity against the A20 lymphoma and that both CD4(+) and CD8(+) T cells were required. Thus, intratumoral administration of lytic peptide might, in addition to providing local tumor control, confer a novel strategy for therapeutic vaccination against cancer.

Topics: Adoptive Transfer; Animals; Antimicrobial Cationic Peptides; Cancer Vaccines; Cattle; Cell Line, Tumor; Female; HMGB1 Protein; Lactoferrin; Lymphocyte Activation; Lymphocyte Depletion; Lymphoma, B-Cell; Mice; Mice, Inbred BALB C; Microscopy, Electron, Scanning; Neoplasm Transplantation; Peptide Fragments; Remission Induction; T-Lymphocytes; Tumor Burden