Faculty Bibliography

In a conceptual study of drug resistance we have used a preclinical model of malignant B-cell lines by combining drug induced growth inhibition and gene expression profiling. In the current report a melphalan resistance profile of 19 genes were weighted by microarray data from the MRC Myeloma IX trial and time to progression following high dose melphalan, to generate an individual melphalan resistance index. The resistance index was subsequently validated in the HOVON65/GMMG-HD4 trial data set to prove the concept. Biologically, the assigned resistance indices were differentially distributed among translocations and cyclin D expression classes. Clinically, the 25% most melphalan resistant, the intermediate 50% and the 25% most sensitive patients had a median progression free survival of 18, 32 and 28 months, respectively (log-rank P-value  = 0.05). Furthermore, the median overall survival was 45 months for the resistant group and not reached for the intermediate and sensitive groups (log-rank P-value  = 0.003) following 38 months median observation. In a multivariate analysis, correcting for age, sex and ISS-staging, we found a high resistance index to be an independent variable associated with inferior progression free survival and overall survival. This study provides clinical proof of concept to use in vitro drug screen for identification of melphalan resistance gene signatures for future functional analysis.

PURPOSE/OBJECTIVE:Medical Research Council (MRC) Myeloma IX was a phase III trial evaluating bisphosphonate and thalidomide-based therapy for newly diagnosed multiple myeloma. Results were reported previously after a median follow-up of 3.7 years (current controlled trials number: ISRCTN68454111). Survival outcomes were reanalyzed after an extended follow-up (median, 5.9 years). EXPERIMENTAL DESIGN/METHODS:At first randomization, patients (N = 1,970) were assigned to bisphosphonate (clodronic acid or zoledronic acid) and induction therapies [cyclophosphamide-vincristine-doxorubicin-dexamethasone (CVAD) or cyclophosphamide-thalidomide-dexamethasone (CTD) followed by high-dose therapy plus autologous stem cell transplantation for younger/fitter patients (intensive pathway), and melphalan-prednisone (MP) or attenuated CTD (CTDa) for older/less fit patients (nonintensive pathway)]. At second randomization, patients were assigned to thalidomide maintenance therapy or no maintenance. Interphase FISH (iFISH) was used to analyze cytogenics. RESULTS:Zoledronic acid significantly improved progression-free survival (PFS; HR, 0.89; P = 0.02) and overall survival (OS; HR, 0.86; P = 0.01) compared with clodronic acid. In the intensive pathway, CTD showed noninferior PFS and OS compared with CVAD, with a trend toward improved OS in patients with favorable cytogenics (P = 0.068). In the nonintensive pathway, CTDa significantly improved PFS (HR, 0.81; P = 0.007) compared with MP and there was an emergent survival benefit after 18 to 24 months. Thalidomide maintenance improved PFS (HR, 1.44; P < 0.0001) but not OS (HR, 0.96; P = 0.70), and was associated with shorter OS in patients with adverse cytogenics (P = 0.01). CONCLUSIONS:Long-term follow-up is essential to identify clinically meaningful treatment effects in myeloma subgroups based on cytogenetics.

Significant benefits for zoledronic acid (ZOL) over clodronate acid (CLO) were seen in the Medical Research Council Myeloma IX randomized trial. ZOL significantly reduced skeletal-related events (SREs), and improved progression-free survival and overall survival (OS), making it the bisphosphonate of choice for newly diagnosed myeloma patients. In this analysis of Myeloma IX data, we have investigated the impact of response on bone disease in 1111 transplant-eligible patients. At posttransplant day 100, complete response (CR) was seen in 48% of patients, very good partial response (VGPR) in 20%, and partial response (PR) in 23%. For patients in VGPR or less, ZOL was superior to CLO in reducing SREs (P = .048), whereas for patients in CR, both agents were equivalent (P = .83). For OS, ZOL was associated with a significant benefit in patients in PR (P = .0091). No difference in OS was seen with patients in CR (P = .91) or VGPR (P = .74). These findings indicate that response category posttransplant may influence the impact of bisphosphonate therapy.

In this issue of Blood, Gay et al provide important new information that can be used to design future phase 3 trials.

To identify variants for multiple myeloma risk, we conducted a genome-wide association study with validation in additional series totaling 4,692 individuals with multiple myeloma (cases) and 10,990 controls. We identified four risk loci at 3q26.2 (rs10936599, P = 8.70 × 10(-14)), 6p21.33 (rs2285803, PSORS1C2, P = 9.67 × 10(-11)), 17p11.2 (rs4273077, TNFRSF13B, P = 7.67 × 10(-9)) and 22q13.1 (rs877529, CBX7, P = 7.63 × 10(-16)). These data provide further evidence for genetic susceptibility to this B-cell hematological malignancy, as well as insight into the biological basis of predisposition.

Multiple myeloma (MM) cells rely on protein homeostatic mechanisms for survival. These mechanisms could be therapeutically targeted via modulation of the heat shock response. We studied the roles of Hsp72 and Hsc70, and show that the two major cytoplasmic Hsp70s play a key role in regulating protein homeostasis and controlling multiple oncogenic pathways in MM, and their inhibition can lead to myeloma cell death. Our study provides further evidence that targeting Hsp70 represents a novel therapeutic approach which may be effective in the treatment of MM.

The first of the so-called "novel agents" (thalidomide, lenalidomide, and bortezomib), thalidomide has demonstrated activity as a single agent and in combination with other agents in patients with relapsed and/or refractory MM. The combination of melphalan, prednisone, and thalidomide (MPT) has become a standard treatment option for newly diagnosed patients who are ineligible for high-dose chemotherapy with autologous stem cell transplantation (ASCT). For patients intending to undergo ASCT, the combination of thalidomide, dexamethasone and cyclophosphamide can be used as a non-myelosuppressive induction regimen. Treatment with thalidomide is associated with an increased risk of developing peripheral neuropathy, which can be managed with dose reductions and discontinuation, and venous thromboembolism, which warrants thromboprophylaxis. While its adverse event profile may preclude prolonged use as maintenance therapy, thalidomide is an effective and well-tolerated salvage therapy option. Ongoing trials continue to evaluate novel thalidomide-based regimens to further optimize the use of thalidomide in the management of MM.

A number of specific chromosomal abnormalities define the subgroups of multiple myeloma. In a meta-analysis of two genome-wide association studies of multiple myeloma including a total of 1,661 affected individuals, we investigated risk for developing a specific tumor karyotype. The t(11;14)(q13;q32) translocation in which CCND1 is placed under the control of the immunoglobulin heavy chain enhancer was strongly associated with the CCND1 c.870G>A polymorphism (P = 7.96 × 10(-11)). These results provide a model in which a constitutive genetic factor is associated with risk of a specific chromosomal translocation.