Time to Spare Newly Diagnosed Non Transplant Eligible Myeloma (eNDMM) from Thalidomide

Background. Thalidomide is one of the most prescribed regimens upfront in eNDMM, e.g. elderly myeloma, essentially as melphalan-prednisone-Thalidomide (MPT). Several options are offered at 1^st and 2^nd relapse to patients initially exposed to Thalidomide with either bortezomib or lenalidomide-based therapy.

On the other hand, the second most prescribed drug in elderly myeloma upfront is Bortezomib, primarily as Bortezomib-melphalan-prednisone (VMP), the 2nd standard of care upfront in Multiple Myeloma (MM) ineligible for transplantation. Interestingly, lenalidomide is the drug of choice at first relapse in the vast majority of cases in most countries where lenalidomide is approved at first relapse and beyond. In this situation, it is likely that the patients would not receive thalidomide throughout the disease course of myeloma.

We sought to analyse whether patients not exposed to thalidomide upfront, and that were solely exposed to the 2 drugs, bortezomib-based regimen and lenalidomide-based therapy would have a lower survival than patients exposed to all 3 drugs, e.g. thalidomide, lenaldiomide and bortezomib.

Method. A total of 145 patients were recruited in this multicentric study, 46,2% were in the thalidomide upfront exposed arm and 53,8% had 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. If not exposed to thalidomide, the patients were to have received bortezomib upfront and lenalidomide first relapse or vice versa.

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), with 11% dose reduction. In the non-exposed thalidomide group, all patients had bortezomib upfront, patients received Vd, VCd or VMP upfront; lenalidomide was then given at first relapse to all patients. The median dose administered of bortezomib was 1.3mg/m², for a median of 5 cycles (2-9).

Results. Overall, the median age was 73 years (range, 65 - 85), with 35% aged >75. The M/F ratio was 1.1, 38% were ISS 3, the median b2m was 5.5mg/L, 26% had an ECOG score ≥ 2, 42% had renal insufficiency, 11% had elevated LDH, 8% presence of plasmacytoma, and 14% had adverse FISH (del17p, t(4;14) and or t(14;16)). There was no difference in patients' characteristics across studied groups, according to exposure or not to thalidomide.

With a median follow-up of 5 years, 60% have died overall; 69% in the thalidomide exposed group versus 52% in the thalidomide non-exposed group (p=0.027). The median OS of thalidomide exposed patients was 55.7 months (46;65) versus 44 months (35;53) in the thalidomide non exposed patients (p=0.079). In the thalidomide exposed group, the median PFS of the thalidomide, bortezomib then lenalidomide lines were 27 months (24;30), 11 months (8;13) and 13 months (10;15). In the thalidomide non-exposed group, the median PFS of bortezomib then lenalidomide lines were 17 months (13;21) and 13 months (6;20).

We then studied the survival of patients from onset of first relapse in the thalidomide exposed group, e.g. upon treatment with bortezomib, followed by lenalidomide at subsequent relapse, 22.5 months (10;34) compared to patients in the thalidomide non-exposed group that received bortezomib upfront and lenalidomide at first relapse, 44 months (35;53), p=0.005.

Conclusion. Overall, thalidomide exposed versus non exposed groups had similar OS, while OS was significantly lower in the thalidomide exposed patients at first relapse onset versus in the thalidomide non exposed patients from diagnosis. This data seems to recommend use of bortezomib- and lenalidomide-based regimens as early as possible in the myeloma disease course, but not to abandon thalidomide. Study of the impact of thalidomide in the post bortezomib, lenalidomide and pomalidomide era might thus be important to study and optimize.