Composition of the Immune Environment at Baseline Correlates with Time to Response and Treatment Outcome in Newly Diagnosed Transplant-Ineligible Multiple Myeloma (MM) Patients Randomized to Krd or Ktd Followed By Carfilzomib Maintenance or Observation (AGMT_MM 02 Study)

Background Rapid induction of remission is a favorable factor in pts with Hodgkin's disease and DLBCL. In MM, only few data are available on the impact of response kinetics on outcome in newly diagnosed transplant ineligible MM pts. Recently, (Abstract EP971, EHA 2021) we described a significant correlation between time to response and progression-free survival (PFS) and overall survival in this patient population. Response and time to response depend on several factors such as the biology of the underlying myeloma clone(s), the activity of the treatment regimen, and on the composition of the bone marrow immune environment. Here, we evaluated possible interconnections between the bone marrow immune environment at baseline and the time to response to therapy in a series of pts randomized to either 9 cycles KRd or KTd induction therapy followed by a second randomization to carfilzomib maintenance or observation. Patients and Methods Composition of the immune environment at baseline was analyzed in 55 pts with newly diagnosed transplant ineligible MM enrolled in a randomized phase II trial (AGMT_MM 02). Median age: 74 years (range: 58-84 years), ISS I: 21.8%, ISS II: 41.8%, and ISS III: 36.4%, cytogenetics: 30.9% high risk, 40% standard risk, 29.1% unknown, ECOG Status 0: 54.5%, 1: 45.6%. Treatment: Carfilzomib : Cycle 1 day 1+2: 20mg/m 2, days 8+9 and 15+16: 27 mg/m 2 ; Cycle 2 day 1,2,8,9,15 + 16: 27 mg/m 2 Cycle 3-9: 56mg/m 2 on days 1, 8 and 15. Lenalidomide: 25mg p.o. on days 1-21/cycle or thalidomide: 100 mg p.o. on days 1-28; in pts ≥75 years of age 50mg p.o. on days 1-28, dexamethasone: 40 mg p.o. on days 1, 8, 15, 22 (± 1 day), in pts ≥ 75 years of age 20 mg p.o. this treatment was administered for nine cycles. Thereafter, pts were randomized to carfilzomib maintenance at last tolerated dose on days 1+15 or to observation for 12 cycles. BM samples were stained with 3 different antibody combinations for the analysis of T, B and NK cells (T cells: CD45RA, CD127, CD8, TCRgd, CD25, CD197, CD4, CD3, B/NK cells: CD57, CCR7, CD314, CD85j, CD62L, CD3, CD16, CD56, CD335, HLADR, CD337). We used a semi-automated pipeline to unveil full cellular diversity based on unbiased clustering. The median and range of each cellular subgroup was calculated and compared between pts with short or longer time to response (< or ≥119 days (median)). Statistical significance of these comparisons was calculated using the Wilcoxon test. Results Median FU was 20.5 months. Twenty of