Carfilzomib Thalidomide and Dexamethasone Is Safe and Effective in the Treatment of Relapsed/Refractory Multiple Myeloma: Preliminary Outcome from the Open Label Phase II ALLGMM018/AMN003 Study

Background:

Carfilzomib lenalidomide and dexamethasone (KRd) is FDA-approved for the treatment relapsed/refractory multiple myeloma (RRMM) based on data from the ASPIRE study (Stewart K et al. NEJM 2015). Thalidomide, a first generation immunomodulatory drug (IMiD) is less costly than lenalidomide and is synergistic in combination with proteasome inhibitors in the treatment of MM. ALLG MM018/ AMN003 is an open label phase II study of carfilzomib thalidomide and dexamethasone (KTd) for patients with RRMM. The primary end point is progression free survival (PFS). Secondary endpoints include overall response rate (ORR), duration of response (DOR), safety and health related quality of life.

Method:

Eligible patients were those with RRMM who have had 1-3 prior lines of treatment. The KTd regimen consisted of carfilzomib [20mg/m² IV C1D1 and 2, 56mg/m² (36mg/m² for patients age ≥75 years) from C1D8 onwards], thalidomide (100mg po nocte) and dexamethasone [40mg (20mg for patients age ≥75 years) po weekly], in a 28-day cycle. After 12 cycles, thalidomide was omitted and Kd [carfilzomib 56mg/m² (36/m² for patients age ≥75 years) on days 1,2,15,16 and dexamethasone 40mg (20mg for patients age ≥75 years) on days 1,15 every 28 days]was continued for a further 6 cycles. Peripheral blood and bone marrow aspirate and trephine for correlative studies were collected from the first 30 patients, at baseline, after cycle 6 and at confirmed disease progression. The aim of the correlative study was to assess for immunological correlates to clinical outcome. Immunological parameters that will be assessed include NK and T cells subsets on peripheral blood via mass cytometry (CyTOF). On the bone marrow trephine, NK cells, T cells, GRP78 expression within CD38 positive plasma cells, PD1 and PDL1 expression will be assessed at the myeloma site and the surrounding microenvironment using OPAL multiplex immunohistochemistry technology.

Results: Between March 2017 to June 2018, 56 patients (median age 66 years, range 56-79; 77% Caucasian and 23% Asian) out of the planned 100 were enrolled, with a median follow up of 4.9 (range, 1.0-13.7) months. Response rates in 39 evaluable patients were ≥MR (97%), ≥PR (89%) and ≥VGPR (66%). Median PFS is not reached, and no patients with ≥MR have relapsed. Grade ≥3/4 AEs occurred in 56% of patients, the most common of which were peripheral sensory neuropathy (13%), dyspnoea (13%) and infections (7%). All grade cardiovascular AEs included dyspnoea (27%), cardiac complications (5%), systemic-hypertension (9%) and pulmonary-hypertension (1.9%), however very few were grade ≥3. Three patients have died on study from disease complications, haemorrhage, and primary cardiac ischaemic event. Thus far, we have not found a significant difference in rates or profile of adverse events between the Caucasian versus Asian subgroups of patients.

Conclusion: This preliminary analysis demonstrates that the KTd combination is a tolerable regimen for patients with RRMM with a safety profile in line with previous reports for each of carfilzomib and thalidomide. Initial response rates appear very promising and durable with responses up to 13.7 months thus far in some patients. Patient accrual is ongoing.