High Expression of the Thalidomide-Binding Protein Cereblon (CRBN) Is Associated with Improved Clinical Response in Patients with Multiple Myeloma Treated with Lenalidomide and Dexamethasone

Abstract Abstract 2879 Background: Immunomodulatory drugs (IMiDs) are highly active in the treatment of multiple myeloma (MM), but the mechanisms of action are still not completely understood. Recently, cereblon (CRBN) has been identified as the primary target of thalidomide teratogenicity (Ito K et al, 2010) and, moreover as an essential requirement for IMiD therapy (Zhu YX et al, 2011). We wanted to investigate, if expression levels of CRBN could serve as a predictor of response. Patients and Methods: We measured CRBN mRNA expression in bone marrow samples of 44 well characterized MM patients treated with lenalidomide containing regimens, myeloma cell lines, and normal bone marrow (BM), using real time PCR. The median age of patients was 65 years (range: 37–85 years). Nine patients had ISS-stage I, 9 stage II, and 26 had stage III. All patients, except 12, were newly diagnosed. None of the patients had been exposed to lenalidomide before study entry. Full data documentation for response evaluation (&gt; 2 cycles) was available in 37 patients (84%). Of these, lenalidomide was given in combination with dexamethasone in 27 patients with a starting dose of 25 mg per day on days 1–21 in a 28 days cycle, in combination with melphalan and prednisone (MPR, starting dose of lenalidomide 10 mg per day on days 1–21) in 9 patients, and in combination with bendamustine in 1 patient. Results: Normal BM was used as a reference with an expression level of one. All multiple myeloma cell lines tested (U266, KMS-12-BM, OPM-2, NCL-H929, MM.1S, SK-MM-1, and RPMI8226), had a higher CRBN expression than normal BM. CRBN was detected in all 44 MM samples distributed over a range covering 3 orders of magnitude (0.31 to 462.08-fold relative to normal BM; median: 3.61). Lenalidomide-based therapy resulted in CR in 3 (8%), nCR in 2 (5%), VGPR in 4 (11%), PR in 17 (46%), and in MR in 4 patients (11%), respectively. Three patients (8%) had SD, and 4 (11%) had PD. Median CRBN expression was three times higher in responding (≥MR) patients compared to non-responders (3.65 vs. 0.99, p&lt;0.01). In addition, a significant correlation between quality of response and CRBN expression (r=0.34) was observed. This correlation remained statistically significant after exclusion of previously treated patients (r=0.37, p=0.02). Interestingly, among 9 available patients who had been pretreated, the lowest level of CRBN expression (0.90) was noted in the patient who progressed during lenalidomide treatment, indicating a predictive potential of CRBN expression also in pre-treated patients. When the analysis was restricted to the 27 patients who had uniformly been treated with lenalidomide and dexamethasone, an even more pronounced association between myeloma response and CRBN expression was noted (r=0.45; p=0.008). In patients with SD or PD, median CRBN expression was lower than in normal BM, while a higher CRBN expression was found in all patients with CR, nCR, VGPR, PR or MR (Table 1), suggesting that CRBN was required for anti-myeloma activity in these patients. This applied also to patients with marked myeloma response (CR, nCR, VGPR) and patients with PD (r=0.82; p= 0.003) (Figure 1). Univariate analysis between established prognostic factors such as beta-2-microglobulin, albumin, ISS stage, Hb, FISH defined cytogenetic aberrations, and response revealed no significant correlation in this patient cohort. A highly significant correlation between expression of CRBN and IRF4, an important transcription factor required for myeloma survival (p=0.00007), and XBP1 (p=0.00004) was observed. For PAX5 and BLIMP no such association were noted. When primary myeloma cells of 5 patients and cell lines (U 266, KMS-12-M) were exposed to lenalidomide, a significant down regulation of IRF4, but not of CRBN was found. Conclusion: Our studies show a significant association between CRBN expression and myeloma response in patients treated with lenalidomide containing regimens, especially in those receiving lenalidomide and dexamethasone therapy. These findings should be confirmed in larger, prospective clinical trials. Disclosures: Jäger: Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Mundipharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; AMGEN: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biogen: Research Funding. </jats:sec

Monokine Induced by Interferon-γ (MIG) Serum Levels Are a Marker of Disease Load and Correlate with Prognosis in Multiple Myeloma.

Abstract Background and Aims: Monokine-induced by interferon-γ (MIG) is a chemokine that is produced by monocytes and macrophages in response to interferon-γ and acts as a chemoattractant mainly to T-lymphocytes in inflammatory processes. MIG has also been suggested to act in an autocrine loop to stimulate tumour cells through its receptor CXCR3, which is known to be expressed in myeloma cells. However, it is presently unclear if MIG is of biologic significance in myeloma in vivo. We have recently shown that multiple myeloma oncogene 1 (MUM1) expression in myeloma cells correlates with prognosis in this disease (Heintel D et al., ASH 2005), and MUM1 was found to upregulate MIG gene expression in B cell malignancies (Uranishi M et al., Leukemia 2005). This led us to evaluate the potential prognostic significance of MIG serum levels in a series of well characterized myeloma patients. Methods: 105 newly diagnosed multiple myeloma patients (median age 69.3 years, range 39.4–90.5) were enrolled. 18 patients presented with Durie/Salmon stage I disease, 9 had stage II and 78 had stage III. MIG serum levels were determined by a commercially available ELISA (R&amp;D Systems). Serum samples from 17 MGUS patients and 37 age-matched healthy volunteers were used as controls. Results: MIG serum levels were elevated in multiple myeloma patients (median 161.3 pg/ml, range 9.37–1966.0) compared to MGUS patients (median 92.7 pg/ml, range 6.29–1303.1) and healthy controls (median 106.2 pg/ml, range 51.0–390.6). For analysis of myeloma cases, a cut-off level for MIG of 200pg/ml (=95th percentile of MIG in controls) was chosen to identify low and high MIG expressers. Using the cut-off as defined above, 63 patients with low MIG serum levels and 42 high MIG expressers were identified in a population of 105 myeloma patients. MIG serum levels in myeloma patients showed strong correlations with several markers of tumour load including low albumin and high β2-microglobulin. Interestingly, no correlation was found with C-reactive protein levels, indicating that MIG is not associated with an inflammatory response in myeloma. Median survival was significantly shorter in patients with high MIG serum levels compared to patients with low MIG expression (median not reached vs. 17.0 months, p&amp;lt;0.001; see figure). Conclusions: MIG serum levels correlate with markers of disease burden in myeloma and high MIG levels are associated with a poor outcome in this disease. Overall Survival: low vs. high MIG serum levels Overall Survival: low vs. high MIG serum levels</jats:p