Impact Of FISH Abnormalities On Response To Lenalidomide In Patients With Multiple Myeloma

Multiple myeloma (MM) is a heterogeneous disease with variable responses to different therapeutic regimens and wide spectrum of survival. Much of the heterogeneity in the outcomes appear to be related to the underlying primary genetic abnormality, which in the majority of patients consist of either translocations involving the heavy chain region on chromosome 14 (IgH translocation) or trisomies of odd numbered chromosomes. We hypothesized that the response to lenalidomide (Len) therapy would vary significantly based on the underlying molecular subtype of myeloma.

We examined a cohort of 518 patients with available FISH results, who had been exposed to Len-based regimens. Medical records were reviewed and data regarding the best response and time to next therapy following treatment with Len-based regimen was obtained. Data from the first use of Len was collected. Len was given in combination with dexamethasone (Dex) with or without alkylators in combination. Patients who received a combination of IMiD and bortezomib as their first exposure to Len were excluded. Patients were grouped according to whether FISH showed a trisomy or an IgH translocation.

The median age was 62 (28-91), and the median estimated follow up from diagnosis was 52 months (95% CI; 50, 54) with 359 (69%) alive at the time of analysis. An IgH translocation was seen in 129 (30%) of patients and a trisomy in 268 (62%) of patients. IgH translocations included t(11;14) in 92 (18%), t(4;14) in 45 (9%), t(14;16) in 21 (4%); 34 (8%) had both translocations and trisomies. For the current analysis, we included only patients with either a translocation or trisomy (n=397) excluding those with neither or both of the abnormalities.

The median time to start of Len from diagnosis was 0 months (range, 0-64). A PR or better was seen in 80% of patients with trisomy compared with 63% of the patients with translocation (p<0.001); and the response rate was similar among the different translocation types. The median TTNT was 28 months among trisomy pts compared with 17 months for translocated patients (p<0.001, figure). The median TTNT was similar across the different types of translocations (Figure). Among this group, 134 patients proceeded to an autologous SCT after Len induction. Among these patients, no difference was seen in terms of TTNT (29 months for patients with translocation vs. 28 months for those with trisomy (p=0.8). Finally, the TTNT was no different if Len was used with Dex or as part of an alkylator combination.

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The current data supports the hypothesis that the underlying primary genetic abnormality can affect the response to a particular therapy. In this study response to Len was significantly higher in myeloma with trisomy compared with IgH translocated myeloma. Although the routine use of combinations of a proteasome inhibitor plus Len in frontline therapy in all patients with myeloma may overcome the lower response rate in IgH translocated patients, in most countries such a regimen is not approved or economically feasible. Based on our study, newly diagnosed patients with evidence of trisomy on FISH could be considered for a Len-based regimen such as lenalidomide-low dose dexamethasone. Additional studies should examine if use of bortezomib in patients with IgH translocation will lead to better outcomes compared with Len based therapies.

Lacy:Celgene Corporation: Research Funding. Gertz:Celgene: Honoraria. Dispenzieri:Celgene, Millenium, Jansenn, Pfizer: Research Funding. Kumar:Merck: Consultancy, Honoraria; Celgene: Consultancy, Research Funding; Millennium: The Takeda Oncology Company: Research Funding; Novartis: Research Funding; Genzyme: Research Funding.