Young Trieu

Influence of cytogenetics in patients with relapsed or refractory multiple myeloma treated with lenalidomide plus dexamethasone: adverse effect of deletion 17p13

Although the combination of lenalidomide and dexamethasone is effective therapy for patients with relapsed/refractory multiple myeloma, the influence of high-risk cytogenetic abnormalities on outcomes is unknown. This subanalysis of a large, open-label study investigated the effects of the most common unfavorable cytogenetic abnormalities detected by fluorescence in situ hybridization, del(13q), t(4;14), and del(17p13), in 130 evaluable patients treated with this regimen. Whereas patients with either del(13q) or t(4;14) experienced a median time to progression and overall survival comparable with those without these cytogenetic abnormalities, patients with del(17p13) had a significantly worse outcome, with a median time to progression of 2.22 months (hazard ratio, 2.82; P < .001) and median overall survival of 4.67 months (hazard ratio, 3.23; P < .001). Improved therapeutic strategies are required for this subgroup of patients. This study was registered at www.ClinicalTrials.gov as #NCT00179647.

Multiple myeloma patients with CKS1B gene amplification have a shorter progression-free survival post-autologous stem cell transplantation

The prevalence and prognostic relevance of recurrent gains of CKS1B (cyclin kinase subunit 1B) gene at chromosome 1q21 region was investigated by interphase fluorescence in situ hybridisation in a cohort of 99 multiple myeloma (MM) patients treated with intensive chemotherapy followed by autologous stem cell transplantation. CKS1B amplification (3–8 CKS1B signals) was detected in 31of 99 (31%) patients and was associated with deletions of p53 (P = 0·003) and 13q (P = 0·039) but not with translocation t(11;14) or t(4;14). CKS1B amplification was associated with bone marrow plasmacytosis (P = 0·02), but there was no correlation with patient age, gender, disease stage, lytic bone lesions, albumin, creatinine, C‐reactive protein or beta‐2 microglobulin levels. Patients with CKS1B amplification had a significantly shorter progression‐free survival than those without such amplification (18·5 vs. 25·7 months, P = 0·035). Likewise, a shorter overall survival (44·8 months vs. not reached) was observed; however, the difference did not reach statistical significance (P = 0·20). Seven patients had paired bone marrows obtained at diagnosis and at relapse, the percentage of cells with CKS1B amplification and the level of amplification were significantly increased in the relapse marrows. In this cohort of patients, CKS1B was frequently amplified in MM and may represent genetic instability associated with disease progression.

D(T)PACE as salvage therapy for aggressive or refractory multiple myeloma

Dexamethasone ± thalidomide with infusion of cisplatin, doxorubicin, cyclophosphamide, and etoposide [D(T)PACE] is generally reserved as salvage therapy for aggressive multiple myeloma (MM) or plasma cell leukaemia (PCL) resistant to conventional therapies. The efficacy and durability of this potentially toxic regimen in this setting is unclear. We identified 75 patients who received D(T)PACE for relapsed/refractory MM at two tertiary care centres: Princess Margaret Hospital, Toronto and Mayo Clinic Arizona. At time of D(T)PACE, 16 patients had PCL and three patients had leptomeningeal disease. Patients were heavily pretreated (median three prior regimens, range 1–12; prior autologous stem cell transplant [ASCT] 33%). Overall response rate was 49% (very‐good partial response 16%, partial response 33%) with stable disease in an additional 36%. Median progression‐free survival (PFS) was 5·5 months (95% confidence interval [CI]:4·3–9·8); overall survival (OS) 14·0 months (95% CI:8·7–19·3). Thirty‐five patients proceeded to ASCT or clinical trial, with median PFS for this subset of 13·4 months (95% CI:7·7–20·1) and OS 20·5 months (95% CI:14·8–63·8). D(T)PACE is an effective salvage therapy for heavily pretreated MM patients. Although the overall response rate of 49% in this poor prognosis cohort is reasonable, the PFS is short, suggesting the best role for D(T)PACE is in bridging to definitive therapy, such as transplantation.

Molecular Target Characterization and Antimyeloma Activity of the Novel, Insulin-like Growth Factor 1 Receptor Inhibitor, GTx-134

Purpose: Therapeutic strategies that target insulin-like growth factor 1 receptor (IGF-1R) hold promise in a wide variety of cancers including multiple myeloma (MM). In this study, we describe GTx-134, a novel small-molecule inhibitor of IGF-1R and insulin receptor (IR) and characterized its antitumor activity in preclinical models of MM. Experimental Design: The activity of GTx-134 as a single agent and in combination was tested in MM cell lines and primary patient samples. Downstream effector proteins and correlation with apoptosis was evaluated. Cytotoxcity in bone marrow stroma coculture experiments was assessed. Finally, the in vivo efficacy was evaluated in a human myeloma xenograft model. Results: GTx-134 inhibited the growth of 10 of 14 myeloma cell lines (<5 μmol/L) and induced apoptosis. Sensitivity to GTx-134 correlated with IGF-1R signal inhibition. Expression of MDR-1 and CD45 were associated with resistance to GTx-134. Coculture with insulin-growth factor-1 (IGF-1) or adherence to bone marrow stroma conferred modest resistance, but did not overcome GTx-134–induced cytotoxicity. GTx-134 showed in vitro synergies when combined with dexamethasone or lenalidomide. Further, GTx-134 enhanced the activity of PD173074, a fibroblast growth factor receptor 3 (FGFR3) inhibitor, against t(4;14) myeloma cells. Therapeutic efficacy of GTx-134 was shown against primary cells and xenograft tumors. Although dysregulation of glucose homeostasis was observed in GTx-134–treated mice, impairment of glucose tolerance was modest. Conclusions: These studies support the potential therapeutic efficacy of GTx-134 in MM. Further, they provide a rationale for clinical application in combination with established antimyeloma treatments and novel targeted therapies. Clin Cancer Res; 17(14); 4693–704. ©2011 AACR.