alpha-chymotrypsin and Precursor-Cell-Lymphoblastic-Leukemia-Lymphoma

To determine the safety, target inhibition, and signals of clinical activity of tipifarnib in combination with bortezomib in patients with advanced acute leukemias.. In a "3 + 3" design, patients received escalating doses of tipifarnib (days 1-14) and bortezomib (days 1, 4, 8, 11) every 3 weeks until maximum tolerated dose was reached. Peripheral blood mononuclear cells (PBMC) were collected at days 1, 8, and 22 for measurement of chymotrypsin-like and farnesyltransferase activity. Purified bone marrow leukemic blasts were collected at baseline and at day 8 for measurement of NF-κB activity.. The combination was well-tolerated, and maximum tolerated dose was not reached. Dose-limiting toxicities included diarrhea, fatigue, and sensorimotor neuropathy. Chymotrypsin-like and farnesyltransferase activity within PBMCs were decreased in a majority of patients at day 8. NF-κB activity within leukemic blasts was decreased in a majority of patients at day 8. Complete response with incomplete count recovery was observed in 2 patients, and additional 5 patients had stable disease.. Tipifarnib and bortezomib combination in patients with advanced leukemias was well-tolerated, demonstrated relevant target inhibition, and was associated with signals of clinical activity in patients with advanced and refractory acute leukemias. Future studies of this combination may be warranted in more selected groups of patients in whom these molecular targets are of particular importance.

Topics: Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Boronic Acids; Bortezomib; Chymotrypsin; Farnesyltranstransferase; Female; Humans; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Leukemia, Myeloid, Acute; Leukocytes, Mononuclear; Male; Maximum Tolerated Dose; Middle Aged; NF-kappa B; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proteasome Inhibitors; Pyrazines; Quinolones

To study the mechanism of bortezomib resistance in JurkatB lines derived from T-lymphoblastic lymphoma/leukemia Jurkat line.. Cytotoxicities of popular chemotherapeutic drugs to JurkatB cells were analyzed by trypan blue assay. Functional drug efflux in JurkatB cells was determined by flow cytometry utilizing daunorubicin and the expression of P-glycoprotein (P-gp) was detected by Western blot. mRNA expression levels of proteasome beta5 subunit (PSMB5) were measured by quantitation real-time reverse transcription polymerase chain reaction. In situ hybridization was performed to detect the amplification of PSMB5 gene. The chymotrypsin-like activities were assayed by measuring the release of the fluorescent 7-amido-4-methylcoumarin (AMC) from the substrate N-succinyl-Leu-Leu-Val-Tyr-AMC. Cytogenetic studies were performed using R-banded metaphases and fluorescence in situ hybridization (FISH) analysis. IkappaB-alpha levels were detected by Western blot.. No cross-resistance to daunorubicin, adriamycin, vindesine, and etoposide was found in JurkatB cells. No evidence of drug efflux was found in JurkatB cells and the expression of P-gp was negative. The PSMB5 mRNA was overexpressed in highly resistant JurkatB5 and JurkatB1 lines compared with parental Jurkat, corresponding well with the increase of chymotrypsin-like activity and a karyotype of i(14q). Amplification of PSMB5 gene was demonstrated by in situ hybridization and FISH. The decreased IkappaB-alpha level in JurkatB5 cells after bortezomib treatment indicating an upregulation of nuclear factor-kappaB (NF-kappaB) activity.. The mechanism of bortezomib resistance is different from that of multidrug resistance. Overexpression of PSMB5 is an important mechanism for bortezomib resistance in JurkatB lines. NF-kappaB may play a critical role in evading the apoptotic effects.

Topics: Antineoplastic Agents; Boronic Acids; Bortezomib; Cell Survival; Chymotrypsin; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Humans; Jurkat Cells; K562 Cells; Leukemia, T-Cell; Lymphoma, T-Cell; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proteasome Endopeptidase Complex; Pyrazines; Ubiquitin

We evaluated whether the proteasomal chymotrypsin-like (ChT-L) activity is increased in plasma of patients with acute lymphoblastic (ALL), acute myeloblastic (AML) and chronic lymphocytic (CLL) leukemias.. The activity was assayed using the fluorogenic peptide substrate in the presence of an artificial activator sodium dodecyl sulfate (SDS) in the plasma of healthy donors (n=15) and ALL (n=15), AML (n=28) and CLL (n=22) patients.. The activity was significantly (P<0.001) higher in the plasma of ALL and AML patients at the diagnosis than in healthy subjects and decreased after therapy or remained unchanged or rose during relapse. By contrast, in CLL patients at the diagnosis, the activity did not differ significantly from the healthy controls. In each group, the activity positively correlated with the serum lactic dehydrogenase activity.. Plasma proteasome ChT-L activity can be a useful bio-marker for patients with acute leukemia at the blast stage.

Topics: Adolescent; Adult; Aged; Case-Control Studies; Chymotrypsin; Female; Humans; Hydrolysis; L-Lactate Dehydrogenase; Leukemia; Leukemia, Lymphocytic, Chronic, B-Cell; Leukemia, Myeloid, Acute; Male; Middle Aged; Oligopeptides; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Protein Subunits; Sodium Dodecyl Sulfate