11q Deletion (del11q) Is Not a Prognostic Factor for Adverse Outcomes for Patients with Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (CLL/SLL) Treated with Ibrutinib: Pooled Data from 3 Randomized Phase 3 Studies

Background: Patients (pts) with CLL/SLL that have del11q tend to have relatively short remission durations and shorter overall survival (OS) with standard chemotherapy regimens. Ibrutinib (ibr), a first-in-class, oral, once-daily inhibitor of Bruton's tyrosine kinase (BTK) is indicated by the US FDA for the treatment of pts with CLL/SLL and allows for treatment without chemotherapy. In phase 3 studies, treatment with single-agent ibr was superior to treatment with ofatumumab (ofa) in relapsed/refractory (R/R) CLL/SLL (RESONATE; Byrd, N Engl J Med 2013) or chlorambucil (clb) in treatment-naïve (TN) CLL/SLL (RESONATE-2; Burger, N Engl J Med 2015); treatment with ibr + bendamustine/rituximab (BR) was also superior to treatment with BR in R/R CLL/SLL (HELIOS; Chanan-Khan, Lancet Oncol 2016). We examined the outcome of pts in these 3 studies who did or did not have del11q to determine the impact of del11q on clinical outcomes.

Methods: In RESONATE, pts with R/R CLL/SLL received ibr 420 mg/day until progressive disease (PD) or unacceptable toxicity (tox) vs ofa for up to 24 weeks (300 mg week 1, 2000 mg weekly for 7 weeks, 2000 mg every 4 weeks for 16 weeks). In RESONATE-2, pts ≥65 years of age with TN CLL/SLL (excluding del17p) received ibr 420 mg/day until PD or tox vs clb 0.5 mg/kg (up to max of 0.8 mg/kg) on days 1 and 15 of each 28-day cycle (≤12 cycles). In HELIOS, pts with R/R CLL/SLL (excluding del17p) received BR (≤6 cycles) with or without ibr 420 mg/day (starting on day 2 of cycle 1) followed by single-agent ibr or placebo continued until PD or tox. Data from pts in the 3 studies were pooled (ibr pool, comparator pool) and analyzed based on whether or not their CLL/SLL had del11q. We performed a multivariate analysis to examine for risk factors prognostic for survival (del11q del17p, age, sex, race, current Rai stage, baseline ECOG PS, number of prior therapies, cytopenias; no multiplicity adjustment).

Results: A total of 1210 pts with del11q data were included in the analysis: 609 in the ibr pool (179 with del11q, 430 without del11q) vs 601 in the comparator pool (149 with del11q, 452 without del11q). Demographics and baseline characteristics were generally similar in pts regardless of del11q status; differences of more than 10% included proportions with bulky disease ≥5 cm (63% vs 49%) and unmutated IGHV (88% vs 72%) in pts with or without del11q, respectively. Median lymphadenopathy and absolute lymphocyte counts were also higher in pts with del11q. At the time of the primary analysis, median treatment durations in the ibr pool were 20.0 mo with del11q and 18.7 mo without del11q; in the comparator pool 5.3 mo with del11q and 8.5 mo without del11q. Overall, ibr-treated pts had higher overall response rate (ORR) and complete response (CR) rates and longer progression-free survival (PFS, Figure) and OS than comparator-treated pts regardless of del11q status. In the ibr pool, the presence of del11q was associated with a trend of longer PFS and OS while in the comparator pool, pts with del11q had shorter PFS (Figure, Table), as compared to pts without del11q. Results were similar when excluding pts with del17p (10% of ibr pool [6%/11% with/without del11q] and 9% of comparator pool [8%/10% with/without del11q]; Table). By multivariate analysis, in the comparator pool, del11q, male sex, >1 prior therapy, presence of cytopenias, and unmutated IGHV (in R/R only) were associated with shorter PFS. However, these differences were not found in the ibr pool. The presence of del11q did not unfavorably impact the tempo of reductions in lymphadenopathy for ibr-treated pts, but did for comparator-treated pts. Adverse events leading to discontinuation were similar in ibr- and comparator-treated pts (12% [9% vs 13% with/without del11q] vs 13% [12% vs 13% with/without del11q]). Deaths within 30 days of last dose occurred in 31 pts (5% [3% vs 6% with/without del11q]) in the ibr pool and 28 pts (5% [6% vs 4% with/without del11q]) in the comparator pool.

Conclusions: Treatment with ibr was superior to comparator regardless of del11q status; the benefit of ibr was most marked for pts with CLL/SLL with del11q. Presence of del11q was associated with a trend of longer PFS and OS in ibr-treated pts and shorter PFS and lower ORR in comparator-treated pts. By multivariate analysis, presence of del11q was a prognostic factor for shorter PFS for comparator-treated pts, but not for ibr-treated pts.

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