Time to Spare Newly Diagnosed Non Transplant Eligible Myeloma from Thalidomide

Background. Bortezomib-melphalan-prednisone (VMP) and melphalan-prednisone-Thalidomide (MPT) are the 2 standards of care upfront in Multiple Myeloma (MM) ineligible for transplantation, along with Bendamustine-prednisone in a very limited indication in Europe. These regimens are based on an alkylator plarform, to which cyclophosphamide might replace melphalan in some countries. For patients initially exposed to Thalidomide several options are offered at first relapse with bortezomib or lenalidomide-based therapy and vive versa at subsequent relapses. For patients initially exposed to bortezomib, either they are retreated with a bortezomib-based regimen or receive a lenalidomide-based therapy, but these patients often have never been exposed to thalidomide throughout their myeloma disease history.

We hypothesized that patients that will receive the 3 agents, thalidomide first followed by bortezomib and lenalidomide at subsequent relapses, will have a prolonged survival compared to patients that had bortezomib-based first followed by lenalidomide at subsequent relapses but never been exposed to thalidomide upfront. We sought to understand the prognostic impact of receiving versus being spared from Thalidomide in elderly MM newly diagnosed.

Method. A total of 76 patients were recruited, 37% had receive thalidomide and 63% never been exposed to thalidomide. Patients were required to be aged ≥65 years, NDMM treated with either thalidomide upfront or never been exposed to thalidomide upfront or later in the myeloma disease course. Response rate was determined according to IMWG. All survival endpoints were evaluated using Kaplan-Meier estimates and compared with the log-rank test.

Results. Overall, the median age was 73 years (range, 65 - 85), with 46% aged >75. The m:f ratio was 1.2, 49% of the patients were ISS 3, the median b2m was 4.5mg/L, 33% had an ECOG score ≥ 2, 47% renal insufficiency, 11% had elevated LDH, 8% presence of plasmacytoma, and 11% had adverse FISH (del17p, t(4;14) and or t(14;16)). There was no difference between the 2 studied groups, according to exposure or not to thalidomide.

In the thalidomide group, all patients had MPT initially for a median of 8 cycles (range 3 – 12), at a median dose of thalidomide of 100mg/day (50-200), 11% dose reduction, an ORR of 79%, a median PFS of 30 months (CI95% 27;32). In the bortezomib group upfront, patients received Vd, VCd or VMP upfront. The median dose administered of bortezomib was 1.3mg/m², for a median of 5 cycles (2-9). The ORR was 67%, a median PFS of 17 months (CI95% 13;20) with 44% at 2-years PFS.

With a median follow-up of 5 years, 93% had relapse, 47% have died. We then sought to compare the OS according to whether the patients were exposed to thalidomide. Interestingly, the median OS of the thalidomide group was 4 years (CI95% 3;5) versus 5 years for the group with no exposition to thalidomide (3.5;6), p=ns. The estimated 6-years OS was 32% and 44% for the 2 groups, respectively.

Conclusion. The sequence of bortezomib-based regimen upfront followed by lenalidomide with no exposure to thalidomide in transplant ineligible patients appeared to be slightly superior to the sequence including-based regimen upfront followed by bortezomib and lenalidomide at subsequent relapses. This data needs to be confirmed in a larger study, but it seems that thalidomide could be spared for elderly NDMM that receive bortezomib-based and lenalidomide-based regimens with possibly an improvement of OS in this latter group with a prolonged follow up.