Quadruplet Vs Sequential Triplet Induction Therapy Approaches to Maximise Response for Newly Diagnosed, Transplant Eligible, Myeloma Patients

Background:

Maximising response in myeloma (MM) patients with effective induction regimens prior to autologous stem cell transplant (ASCT) improves progression-free and overall survival. Triplet regimens combining an immunomodulatory agent (IMiD) and/or proteasome inhibitor (PI) are standard of care, however a more personalised approach is achieved by sequential triplet combinations based on an individual's response. Alternatively, quadruplet regimens may be more effective and new generation PIs such as carfilzomib, with less off-target activity, provide the opportunity to investigate this whilst minimising the risk of increased toxicity.

The UK NCRI Myeloma XI trial is a large, phase III study aiming to answer these questions in transplant eligible (TE) patients comparing the quadruplet carfilzomib, cyclophosphamide, lenalidomide and dexamethasone to the sequential strategy of triplet IMiD combinations (with thalidomide or lenalidomide) followed by additional PI triplet therapy for those with a suboptimal response (<VGPR) prior to ASCT.

Methods:

In 2013, the TE pathway was amended to include KCRD: carfilzomib 36mg/m² IV d1-2,8-9,15-16 (20mg/m² #1d1-2), cyclophosphamide (cyclo) 500mg PO d1,8, lenalidomide (len) 25mg PO d1-21, dexamethasone (dex) 40mg PO d1-4,8-9,15-16). Patients are randomised to this up-front quadruplet or the sequential strategy of CRD: cyclo 500mg PO d1,8, len 25mg PO d1-21 PO daily, dex 40mg PO d1-4, 12-15 or CTD: cyclo 500mg PO d1,8,15 thalidomide 100-200mg PO daily, dex 40mg PO d1-4,12-15 given to max. response - patients with VGPR/CR proceed straight to ASCT, PR/MR are randomised to sequential CVD: cyclo 500mg d1,8,15, bortezomib 1.3mg/m² IV/SC d1,4,8,11, dex 20mg PO d1,2,4,5,8,9,11,12 or nothing and SD/PD all receive sequential CVD. All treatments are given to max. response prior to ASCT, after which there is a maintenance randomisation.

Patients:

1512 patients entered the TE pathway prior to amendment (756 CRD, 756 CTD). Of these, 201 patients with a suboptimal initial response went on to receive CVD, 142 following randomisation (initial response PR/MR) and 59 with NC/PD. 788 (of target n=1036) patients have been randomised post-amendment to date (394 KCRD, 197 CRD, 197 CTD).

Results:

TE patients receiving treatment prior to the amendment had response rates ≥VGPR: CRD 58% vs CTD 52%. For patients receiving the sequential triplet CVD due to a suboptimal response this was upgraded to ≥VGPR in 49% of those with initial MR/PR, 27% with NC/PD. This suggests the overall ≥VGPR rate to this treatment approach prior to ASCT would be approx. 75%. This now needs to be compared to the alternative approach of an upfront quadruplet.

Comparing patients contemporaneously randomised to initial induction the patients receiving KCRD have completed a median 4 cycles (range 1-7), CRD 5 (range 1-10) and CTD 6 (range 1-9). Dose modifications have been required in 62% of patients receiving KCRD (56% to carfilzomib, 42% to lenalidomide) 44% CRD (40% to lenalidomide) and 65% CTD (59% to thalidomide). Data for study drug related toxicity in patients who have completed at least one cycle of initial induction are shown in table 1. Serious adverse events suspected to be due to trial medications have occurred in 37% on KCRD, 32% CRD and 35% CTD.

Updated toxicity and preliminary response analysis on 23/09/15 will be presented at the meeting. This will include a response comparison at the end of initial induction regimen i.e. KCRD vs CRD vs CTD for an anticipated 700 contemporaneous patients who will have completed treatment. Updated response to the sequencing approach (with 250 patients having received sequential CVD) will also be presented and compared.

Conclusions:

In our study KCRD, an outpatient delivered 4-drug regimen combining second generation IMiD and PI drugs, is well-tolerated in TE NDMM patients, comparable to 3-drug regimens. Data will be presented at the meeting to compare the response rates achieved with the different regimens and treatment approaches.

On behalf of the NCRI Haemato-oncology CSG