PF629 CONSOLIDATION FOLLOWING INFUSIONAL DPACE IMPROVES OUTCOMES IN NOVEL AGENT RELAPSED/REFRACTORY MYELOMA PATIENTS

Background: Historical indications for DPACE‐based therapies include salvage treatment of aggressive myeloma (MM) resistant to conventional therapies, plasma cell leukaemia (PCL), and initial presentation with extra‐medullary disease. Aims: We performed a retrospective analysis of DPACE‐treated MM patients from different UK Centres in order to describe its use and establish the best place for its indication. Methods: 59 patients between 2009 and 2017 were eligible for inclusion. Data was collected from chemotherapy databases and patient records. The primary outcome is a descriptive analysis of this UK cohort. Secondary outcomes include response rates, time to next treatment (TTNT) for the following groups (the total cohort, ASCT post‐DPACE vs. No ASCT and according to number of prior therapies (≤2 vs. >2)), overall survival (OS) for total cohort and treatment‐related mortality (TRM). Results: Male/female ratio was 1.5:1. Age (years) distribution was (<50: 28.8%, 51–64: 59.3%, ≥ 65: 11.9%). Myeloma subtypes were: Ig: 76.3%, LC: 15.2%, non‐secretory: 5.1%, PCL: 3.4%). ISS was: I: 25.4%, II: 27.1%, III: 30.5%, unknown: 17%). Number of adverse cytogenetics was: 0: 10.2%, 1: 30.5%, ≥2: 11.9%, unknown: 47.5%). 45.8% of patients had relapsed disease post ASCT prior to DPACE, 47.5% received DPACE as therapy prior to ASCT. The number of patients who received 2 transplants (pre and post) DPACE was 11 (18.6%). The nature of prior therapies was: IMiD: 6.8%, PI: 10.2%, IMiD and PI: 72.9%, chemotherapy only: 1.7%, none: 8.5%). The choice DPACE‐based therapy was: VTDPACE: 35.6%, VRDPACE: 25.4%, DTPACE: 39%. Median number of cycles (range) received was 2 (1–4). Median follow up was 46.7 months. Response rates were: CR: 23.7%, VGPR: 11.9%, PR: 30.5%, MR/SD: 10.1%, PD: 8.5%, unknown: 15.3%. Out of 53 (for TTNT) and 57 (for OS) evaluable patients, median TTNT and median OS for the total cohort were 14.2 months (95% CI: 0.362–0.638) and 15.1 (95% CI: 0.318–0.586), respectively. Median TTNT (ASCT post‐DPACE vs. no ASCT) was 12.8 months, 95% CI: 0.302–0.696, vs. 2.7 months, 95% CI: 0.264–0.738, p = 0.118). Median TTNT according to number of prior therapies was (>2: 5.1 months (95% CI: 0.259–0.741) vs. ≤2: 24.6 months (95% CI: 0.320–0.663), p = 0.34). The majority of patients who received >2 lines of therapy received a prior ASCT (15/17: 88.2%) and only a small group (i.e. 3/17: 17.63%) consolidated DPACE with an ASCT (the second transplant in all 3 patients). In those who received <2 prior therapies, 26/36 (72.2%) received ASCT post‐DPACE. The comparatively longer median TTNT can be attributed to both the lower number of prior therapies as well as the higher rate of ASCT post‐DPACE. TRM was documented in 6 out of 57 evaluable patients (10.5%). Summary/Conclusion: This cohort study demonstrated that DPACE can be beneficial if consolidated with an ASCT, particularly in those with a small number of prior therapies, and is of limited benefit in patients ineligible for ASCT post‐DPACE or those heavily pre‐treated. In order to improve outcomes in the latter, it would be logical to schedule subsequent therapy shortly after DPACE completion to extend or deepen the achieved response.