Ixazomib regimens disappoint in older patients with multiple myeloma

Induction with ixazomib-based regimens appear to be insufficient for older patients newly diagnosed multiple myeloma who are ineligible for transplantation, achieving an unsatisfactory progression-free survival (PFS) rate, reports a recent study.

However, due to its lower rates of adverse events, ixazomib may be a more suitable option for maintenance therapy than bortezomib in those who had achieved deep cytoreduction.

The open-label, multicentre, multi-arm, randomized phase II trial included 175 patients who were assigned to one of four induction treatments: ixazomib with dexamethasone (Id; n=42), Id with cyclophosphamide (ICd; n=61), Id with bendamustine (IBd; n=11), or Id with thalidomide (ITd; n=61). All regimens were followed by maintenance ixazomib for up to 2 years.

The primary objective of the trial was to identify the most promising regimen that could provide a 2-year PFS of 65 percent; a PFS of 50 percent was deemed unsatisfactory.

After a median follow-up of 31 months, the median PFS times were 10, 19, 12, and 14 months in the Id, ICd, ITd, and IBd arms, respectively. The corresponding 2-year PFS estimates were 32 percent, 41 percent, 25 percent, and 40 percent. None of the regimens met the predefined threshold.

In terms of tolerability, the researchers recorded dose reductions in patients receiving triplet therapies than Id. Meanwhile, discontinuation due to adverse events was highest in the ITd arm (17 percent), as opposed to Id (10 percent), ICd (12 percent), or IBd (9 percent).

Grade ≥3 haematologic adverse events were uncommon, ranging from 5 percent in the Id arm to 18 percent in IBd. During the maintenance phase, 15 percent required at least one dose reduction. The rate of grade ≥3 adverse events was low during maintenance.