A multicenter phase II trial to determine the safety and efficacy of combination therapy with denileukin diftitox and cyclophosphamide, doxorubicin, vincristine and prednisone in untreated peripheral T-cell lymphoma: the CONCEPT study.

This phase II study to determine the safety and efficacy of denileukin diftitox (DD) and cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) enrolled patients with newly diagnosed peripheral T-cell lymphoma (PTCL). Forty-nine received DD 18 µg/kg/day (days 1, 2) with CHOP (day 3) every 21 days for ≤ 6-8 cycles. Intent-to-treat (ITT) and safety populations comprised all patients. In the ITT population, the overall response rate was 65%, median duration of response was 30 months and median progression-free survival was 12 months. Median overall survival was not attained at the end of the study, and the overall survival rate was 63.3%. The two most frequent treatment-related adverse events (AEs) were fatigue and nausea. Most frequent AEs ≥ grade 3 within the hematologic system were lymphopenia (24.5%), neutropenia (20.4%) and leukopenia (18.4%). Three treatment-related deaths occurred. DD plus CHOP was well tolerated, and progression-free and overall survival improved versus historical comparison with CHOP alone. Confirmation in larger trials is warranted.

LAGlambda-1: a clinically relevant drug resistant human multiple myeloma tumor murine model that enables rapid evaluation of treatments for multiple myeloma.

We set out to generate new human myeloma tumors that grow in immunodeficient mice and can be used for pathophysiological studies and rapid evaluation of new therapies. Fresh whole core bone marrow (BM) biopsies taken from 33 myeloma patients were engrafted into the hind limb muscle of severe combined immunodeficient (SCID) mice. Human Ig was detected in 28/33 mice and three grew palpable tumors displaying many features of human myeloma including morphology, immunophenotype and BM plasmacytosis. Following intramuscular passage, we generated large numbers of mice with predictable increases in tumor growth and human paraprotein levels. We further characterized the model generated from an IgGlambda-producing tumor known as LAGlambda-1 and determined the effects of the proteasome inhibitor bortezomib, the alkylating agent melphalan, and the DNA damaging agent liposomal doxorubicin, on the growth of this tumor. LAGlambda-1-bearing mice receiving higher doses of bortezomib showed reduced tumor growth whereas a lower dose had no effect. In contrast, melphalan did not significantly alter tumor growth, except minimally at high doses, reflecting the resistance of this patient's tumor to this drug. We also used our intramuscular (i.m.) LAGlambda-1 model to optimize the dosing schedule of liposomal doxorubicin. Low doses administered once daily three days per week decreased tumor growth and human paraprotein levels whereas much higher doses given once weekly had no anti-myeloma effects. Furthermore, LAGlambda-1 cells produce local tumors when injected subcutaneously and lytic lesions when injected intravenously allowing for multiple methods of evaluating the anti-myeloma effects of a variety of agents. Our new clinically relevant SCID models of human myeloma should greatly facilitate drug development and enable novel therapies to quickly move from the laboratory to the clinic.

The proteasome inhibitor PS-341 markedly enhances sensitivity of multiple myeloma tumor cells to chemotherapeutic agents.

Increased nuclear factor kappaB (NF-kappaB) activity is associated with increased tumor cell survival in multiple myeloma. The function of NF-kappaB is inhibited through binding to its inhibitor, IkappaB. Release of activated NF-kappaB follows proteasome-mediated degradation of IkappaB resulting from phosphorylation of the inhibitor and, finally, conjugation with ubiquitin. We report that myeloma cells have enhanced IkappaBalpha phosphorylation and increased NF-kappaB activity compared with normal hematopoietic cells. The proteasome inhibitor PS-341 blocked nuclear translocation of NF-kappaB, blocked NF-kappaB DNA binding, and demonstrated consistent antitumor activity against chemoresistant and chemosensitive myeloma cells. The sensitivity of chemoresistant myeloma cells to chemotherapeutic agents was markedly increased (100,000-1,000,000-fold) when combined with a noncytotoxic dose of PS-341 without affecting normal hematopoietic cells. Similar effects were observed using a dominant negative super-repressor for IkappaBalpha. Thus, these results suggest that inhibition of NF-kappaB with PS-341 may overcome chemoresistance and allow doses of chemotherapeutic agents to be markedly reduced with antitumor effects without significant toxicity.

Identification of polymorphisms of the IkappaBalpha gene associated with an increased risk of multiple myeloma.

When NF-kappaB proteins are bound to IkappaBalpha, they remain in the cytosol, and are unable to act as transcription factors. Phosphorylation of IkappaBalpha at Serine32 and Serine36 has been shown to stimulate ubiquitination followed by proteasome-mediated degradation of IkappaBalpha, resulting in the release of active NF-kappaB. NF-kappaB activity is associated with bone loss and B cell growth as well as chemotherapy resistance. Because previous studies have shown abnormalities of the IkappaBalpha gene in patients with lymphoma, we determined whether alterations of this gene also occur in multiple myeloma (MM). We determined the DNA sequence of the IkappaBalpha gene from bone marrow mononuclear cells from 18 MM patients and 24 healthy subjects as well as two MM cell-lines. We identified eight polymorphisms. Statistically, the prevalence of three polymorphisms, one in exon 1 and two in exon 6, were significantly higher in MM patients (alpha>1) compared with samples from control subjects. Six of eight polymorphisms in myeloma samples have also been identified in previous studies of IkappaBalpha sequences derived from lymphoma samples. In addition, we detected two polymorphisms in the IkappaBalpha gene that have not been previously reported. Together, these results provide the basis for future evaluation the IkappaBalpha/NF-kappaB pathway in MM patients.