Big Prevention Benefits With Daratumumab?

SAN DIEGO — The multiple myeloma (MM) drug daratumumab (Darzalex), an anti-CD38 monoclonal antibody, dramatically reduced progression to active MM or death in patients with high-risk smoldering MM (SMM), a landmark randomized, open-label, phase 3 study found.

Among 390 patients with SMM (194 assigned to daratumumab and 196 to active monitoring), progression to active MM or death over a follow-up of 65.2 (0-76.6) months was 51% lower in the daratumumab group vs active monitoring (34.5% vs 50.5%, hazard ratio [HR], 0.49; 95% CI, 0.36-0.67; P American Society of Hematology (ASH) 2024 Annual Meeting and in a simultaneous publication in The New England Journal of Medicine.

Rahul Banerjee, MD, an assistant professor with the University of Washington and Fred Hutchinson Cancer Center, Seattle, who wasn’t involved with the research, said the study “is a big deal, and I suspect this will ultimately lead to an FDA approval for daratumumab in this setting. If using daratumumab upfront can prevent further myeloma and therefore make patients live longer, this would be immediately adopted at many practices.”

As study first author Meletios Athanasios Dimopoulos, MD, of National and Kapodistrian University of Athens and Alexandra General Hospital, Athens, Greece, noted at a news briefing, SMM is common, affecting 0.5% of the population aged over 40, per a 2023 Iceland study.

“Standard practice is close follow-up without immediate intervention. However, this oftentimes ends in organ tissue damage, and hypercalcemia, bone lesions, renal impairment, and anemia,” Dimopoulos said.

According to him, researchers launched the AQUILA study in light of indications that daratumumab may benefit patients with intermediate- and high-risk SMM.

For the study, researchers recruited patients from 2017 to 2019 in 23 countries with confirmed high-risk SMM for ≤ 5 years (median age, 64 [31-86] years; 47%-49% men; 83% White).

In the daratumumab group, the drug was administered in 28-day cycles until cycle 39, 36 months, or disease progression, whichever came first (median treatment duration, 38 months [35 months]).

At 5 years, progression-free survival (PFS) — the primary endpoint — was 63.1% (daratumumab) and 40.8% (active monitoring). Researchers estimated 60-month PFS rates at 63.1% and 40.8%, respectively, and overall response rates were 63.4% vs 2.0% (P

The 60-month overall survival rates were 93.0% and 86.9% (HR, 0.52; 95% CI, 0.27-0.98) with 15 deaths in the daratumumab and 26 in the active monitoring group.

“During the follow-up period, there was continuous improvement in favor of the daratumumab arm,” Dimopoulos said. “Even after treatment was discontinued at 3 years, or even at 5 or 6 years, there was a continuous benefit from treatment with daratumumab.”

By clinical cutoff in May 2024, 65% of patients taking daratumumab had finished 39 cycles/3 years of treatment vs 40.8% in the active monitoring group. Progressive disease was the most common reason that patients stopped treatment (21.8% and 41.8% of patients in the groups, respectively).

Grade 3/4 treatment-emergent adverse events (TEAEs) occurred in 40.4% (daratumumab) and 30.1% (active monitoring) of patients. The most common was hypertension (5.7% and 4.6%, respectively).

In the daratumumab group, 5.7% discontinued therapy due to TEAEs, which the researchers described as a “low” number, and fatal TEAEs were similar in both groups (1.0% and 2.0%, respectively).

Banerjee said that “one theoretical risk of using daratumumab monotherapy to treat perceived high-risk SMM is that if the patient actually has active multiple myeloma, you are undertreating them. For anyone with HR-SMM, active multiple myeloma must be completely ruled out. I always insist on both a PET-CT and a whole-body MRI to evaluate the bone marrow comprehensively.”

For now, Banerjee said, clinicians should wait for the US Food and Drug Administration approval before prescribing daratumumab for high-risk SMM.

Are there alternatives to reduce the risk for SMM turning into MM? “Generally, I advise close observation in most cases, but we do have clinical trials in this space,” Banerjee said. “Technically, it is possible to consider lenalidomide monotherapy in SMM based on the results of a large phase 3 study. But lenalidomide is expensive and has many side effects. Insurance companies often won’t cover it fully, and patients almost always have at least one side effect.”

Also, he added, “only half of patients saw their high-risk SMM disease burden drop. Lenalidomide also has a clear link to rare, delayed toxicities such as second primary malignancies, which makes us nervous.”

Janssen Pharmaceuticals, the maker of daratumumab, funded the study. Dimopoulos disclosed ties with Sanofi, Regeneron, Menarini, Takeda, GSK, BMS, Janssen Pharmaceuticals, BeiGene, Swixx, AstraZeneca, and Amgen. Banerjee disclosed ties with AbbVie, Adaptive, BMS, Caribou, Genentech/Roche, GSK, Karyopharm Therapeutics, Legend, Johnson & Johnson, Novartis, Pack, Pfizer, Prothena, Sanofi Pasteur, and SparkCures. Some other authors reported various and multiple disclosures, including ties with Janssen Pharmaceuticals.

Randy Dotinga is an independent writer and board member of the Association of Health Care Journalists.