Early treatment with lenalidomide may delay disease progression and prevent end-organ damage in patients with high-risk smoldering multiple myeloma (SMM), according to findings from a phase 3 trial.
While observation is the current standard of care in SMM, early therapy may represent a new standard for patients with high-risk disease, explained, of Winship Cancer Institute, Emory University, Atlanta, and colleagues. Their findings were published in the .
The randomized, open-label, phase 3 study included 182 patients with intermediate- or high-risk SMM. Study patients were randomly allocated to receive either oral lenalidomide at 25 mg daily on days 1-21 of a 28-day cycle or observation.
Study subjects were stratified based on time since SMM diagnosis – 1 year or less vs. more than 1 year, and all patients in the lenalidomide arm received aspirin at 325 mg on days 1-28. Both interventions were maintained until unacceptable toxicity, disease progression, or withdrawal for other reasons.
The primary outcome was progression-free survival (PFS), measured from baseline to the development of symptomatic multiple myeloma (MM). The criteria for progression included evidence of end-organ damage in relation to MM and biochemical disease progression.
The researchers found that at 1 year PFS was 98% in the lenalidomide group and 89% in the observation group. At 2 years, PFS was 93% in the lenalidomide group and 76% in the observation group. PFS was 91% in the lenalidomide group and 66% in the observation group at 3 years (hazard ratio, 0.28; P = .002).
Among lenalidomide-treated patients, grade 3 or 4 hematologic and nonhematologic adverse events occurred in 36 patients (41%). Nonhematologic adverse events occurred in 25 patients (28%).
Frequent AEs among lenalidomide-treated patients included grade 4 decreased neutrophil count (4.5%), as well as grade 3 infections (20.5%), hypertension (9.1%), fatigue (6.8%), skin problems (5.7%), dyspnea (5.7%), and hypokalemia (3.4%). “In most cases, [adverse events] could be managed with dose modifications,” they wrote.
To reduce long-term toxicity, the researchers recommended a 2-year duration of therapy for patients at highest risk.
“Our results support the use of early intervention in patients with high-risk SMM – as defined by the 20/2/20 criteria where our magnitude of benefit was the greatest – rather than continued observation,” the researchers wrote.
The trial was funded by the National Cancer Institute. The authors reported financial affiliations with AbbVie, Aduro Biotech, Amgen, Bristol-Myers Squibb, Celgene, Juno Therapeutics, Kite Pharma, Sanofi, Takeda, and several other companies.
SOURCE: Lonial S et al. J Clin Oncol. 2019 Oct 25.