Impact Of The Proportion Of Metaphases With Isolated Del(5q) On Clinical Outcomes In Lenalidomide (LEN)-Treated Patients With IPSS Low-/Int-1-Risk Myelodysplastic Syndromes (MDS) In MDS-003 and MDS-004

The proportion of aberrant metaphases is prognostic for overall survival (OS) in MDS patients with trisomy 8 (Mallo M, et al. Leuk Res. 2011;35:834-6). The impact of the proportion of metaphases with del(5q) on clinical outcomes, including OS, disease progression and response to therapy with LEN in MDS remains undefined. In two large multicenter studies of LEN (MDS-003 and MDS-004) in RBC transfusion-dependent patients with International Prognostic Scoring System (IPSS) Low- or Intermediate (Int)-1-risk del(5q) MDS, RBC transfusion independence (TI) ≥ 8 weeks was achieved in 51–67% of patients (List A, et al. N Engl J Med. 2006;355:1456-65; Fenaux P, et al. Blood. 2011;118:3765-76). This retrospective analysis evaluated response to treatment, progression to acute myeloid leukemia (AML) and OS by proportion of del(5q) metaphases in patients with isolated del(5q) from the MDS-003 and 004 studies.

In order to allow sufficient patient numbers for analysis, ≥ 16 metaphases were evaluated for del(5q) by standard karyotyping (MDS-003 and MDS-004) and 200 interphase nuclei were evaluated by fluorescence in situ hybridization (FISH; MDS-004 only) using a probe for the commonly deleted region 5q31 (LSI EGR1/D5S721, Abbott, Wiesbaden, Germany). Patients received LEN on days 1–21 of each 28-day cycle (10 mg) or continuously (5 mg or 10 mg), or placebo. In MDS-004, patients randomized to placebo could cross over to LEN 5 mg by week 16. RBC-TI ≥ 26 weeks, time to AML progression and OS were analyzed by the proportion of del(5q) metaphases or interphases (≤ 60% vs > 60%) using standard karyotyping and FISH, respectively.

Of the 353 patients from MDS-003 and MDS-004, 194 had isolated del(5q) by standard karyotyping; median proportion of del(5q) metaphases was 96% (range 4–100). Baseline characteristics including age, time from diagnosis, RBC transfusion burden, hemoglobin level, platelet and absolute neutrophil counts were comparable among patients with ≤ 60% (n = 21) and > 60% (n = 173) del(5q) metaphases. Rates of RBC-TI ≥ 26 weeks were similar across patients in the ≤ 60% and > 60% groups (P = 0.6515). Time to AML progression was comparable for patients in the ≤ 60% group versus the > 60% group (log-rank test P = 0.9802); 2-year rates were 22.2% (95% confidence interval [CI]: 7.7–54.5%) and 14.6% (95% CI: 9.9–21.2%), respectively. Time to AML progression was similar when analyzed with death without AML as competing risk (Gray’s test P = 0.5514). OS was longer in the > 60% versus the ≤ 60% group (log-rank test P = 0.0436); median OS was 3.7 years (95% CI: 3.0–4.2) and 2.4 years (95% CI: 1.5–4.9), respectively. In MDS-004, the proportion of del(5q) interphases was analyzed using FISH in 106 patients, including 46 with ≤ 60% and 60 with > 60%. When analyzed by FISH, rates of RBC-TI ≥ 26 weeks were similar across patients in the ≤ 60% and > 60% groups (P = 1.000). Time to AML progression and OS were similar across these groups (log-rank test P = 0.7311 and P = 0.8639, respectively) when analyzed by FISH. In the ≤ 60% and > 60% groups respectively, 2-year AML progression rates were 14.8% (95% CI: 6.9–30.1%) and 18.6% (95% CI: 10.4–32.0%), and median OS was 3.1 years (95% CI: 2.3–4.8) and 2.9 years (95% CI: 2.3–4.4). Time to AML progression was similar when analyzed with death without AML as competing risk (Gray’s test P = 0.8631).

In IPSS Low- or Int-1-risk MDS patients with isolated del(5q) treated with LEN in MDS-003 and MDS-004 studies, baseline characteristics, RBC-TI ≥ 26 weeks and AML progression were comparable in patients with > 60% versus ≤ 60% del(5q) metaphases. Although similar across groups when analyzed by FISH in a subset of patients, surprisingly, OS was longer in patients with > 60% del(5q) metaphases than in those with ≤ 60% del(5q) metaphases by standard karyotyping. However, the number of patients with ≤ 60% del(5q) metaphases was limited and no adjustment was made for multiple testing. These findings suggest that the number of cells with the isolated del(5q) abnormality measured by FISH does not impact clinical outcome in this RBC transfusion-dependent study population, but this finding could not be confirmed for OS by standard karyotyping.

Giagounidis:Celgene: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees. List:Celgene: Serve on Celgene Data Safety & Monitoring Committee Other. Hellström-Lindberg:Celgene: Membership on an entity’s Board of Directors or advisory committees, Research Funding. Sekeres:Celgene: Membership on an entity’s Board of Directors or advisory committees; Amgen: Membership on an entity’s Board of Directors or advisory committees. Mufti:Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding. Schlegelberger:Celgene: Consultancy. Morrill:Celgene: Employment, Equity Ownership. Wu:Celgene: Employment, Equity Ownership. Skikne:Celgene: Employment, Equity Ownership. Fenaux:Celgene: Honoraria.