P-051: Inferior outcomes for Multiple Myeloma (MM) patients (pts) harbouring t(11;14) and the promise of venetoclax, real-world Australian retrospective

Background

Traditionally, MM harbouring t(11;14) is considered standard risk disease. In the era of novel therapies however, pts with t(11;14) are reported to have inferior outcomes to other standard risk pts. Evidence of response to the BCL-2 inhibitor, Venetoclax (Ven), has further increased interest in understanding outcomes of t(11;14) pts. Here we aim to describe the historical outcomes of t(11;14) MM and response to Ven in a real-world cohort of Australian pts.

Methods

This was a retrospective, multicentre study conducted by members of the Australasian Leukaemia and Lymphoma Group, Myeloma Working Party. Cases were identified by interrogation of cytogenetics/FISH database from 2010 to 2019 inclusive. Baseline patient and disease characteristics, treatment exposure and outcomes were extracted from hospital medical records. Descriptive statistics, and survival analyses were performed as appropriate.

Results

Seventy-four pts [median age 65 years (yrs), range (43-85)] were identified across seven centres. 43% pts had ISS Stage III MM with 88% harbouring additional cytogenetic abnormalities, incl. 13% with gain in 1q and 12% with del(17p). The majority (81%) of pts received proteasome inhibitor (PI)-based 1st line therapy with 60% having an upfront autologous stem cell transplant (ASCT) and 54% having immunomodulatory drug (IMiD)-based maintenance therapy. Two patients received an allogeneic stem cell transplant after ASCT. The overall response rate (ORR) was 86% with 38% achieving very good partial response (VGPR) or better. The median progression free survival-1 (PFS1) was 1.91 yrs (95% CI 1.73-2.56) [PI-based, n=60, PFS 1.84yrs (95% CI 1.61-2.41) vs IMiD-based, n=5, PFS 4.58yrs (95% CI 1.16-5.51), HR 0.68 p=0.45] The median overall survival (OS) was 5.35 yrs (95% CI 4.12-6.56). Second and third line therapy was predominantly IMiD-based with recent introduction of anti-CD38 monoclonal antibodies (mAbs). Median PFS-2 was 0.77 yrs (95% CI 0.39-0.98) while median PFS-3 was 0.65 yrs (95% CI 0.34-1.16). Eleven pts (median 3 prior lines of therapy) were given Ven [Six pts in combination with PI, three with PI and mAbs and two with dexamethasone]. ORR to Ven was 55% with 45% ≥ VGPR. Median PFS with Ven was 0.54 yrs (85% CI 0.05-2.17). Median PFS for patients with 1-4 lines (n=6) was 1.22 years and median PFS for patients with 5 lines or more (n=5) was 0.54 years, HR 0.56 (95% CI 0.12-2.5).

Conclusion

For pts harbouring t(11;14), the duration of response to PI-based 1st line therapy is suboptimal even with the use of ASCT consolidation in the majority of patients. Despite multiple prior lines of therapy, Venetoclax shows promising results and every effort should be made for early identification of this cytogenetic lesion. Further studies are required to examine the impact of novel triplet and quadruplet combination therapy and use of venetoclax early in the disease course of this sub-group of patients.