Under-the-skin myeloma treatment linked to better survival in study
Medicare analysis compared injectable and IV treatments in older adults
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Darzalex Faspro, an under-the-skin injection therapy, was associated with better survival than Darzalex, an intravenous (IV) infusion therapy, among people with multiple myeloma.
The finding comes from an analysis of Medicare data involving patients ages 65 and older. Medicare is the U.S. government health insurance program that primarily covers older adults.
Longer treatment duration may help explain survival findings
Both treatments contain the same cancer-fighting antibody, daratumumab, and clinical trials have shown similar effectiveness. However, the new analysis found that patients receiving Darzalex Faspro were less likely to discontinue treatment and had a lower risk of serious infections. Researchers suggested that these differences may help explain the survival findings.
“These findings support the continued use of [Darzalex Faspro] in routine clinical practice, as an effective and patient-centric formulation, that favorably impacts patient benefit and risk in the real-world setting,” the team wrote.
The study, “Increased Overall Survival for Subcutaneous Versus Intravenous Daratumumab in Medicare Beneficiaries With Multiple Myeloma,” was published in Clinical Lymphoma, Myeloma & Leukemia. The research was funded by Halozyme Therapeutics, whose technology enables Darzalex Faspro to be injected under the skin.
Myeloma is a form of blood cancer marked by the uncontrolled growth of plasma cells, a type of immune cell, in the bone marrow. Darzalex and Darzalex Faspro both contain daratumumab, an antibody that targets the CD38 protein on myeloma cells, helping the immune system destroy them. Darzalex Faspro also contains hyaluronidase, an enzyme that allows the treatment to be injected under the skin. Both treatments are marketed by Johnson & Johnson, and several study authors reported consulting relationships with the company.
Darzalex was approved first and is given through an IV infusion. Darzalex Faspro was developed later as a more convenient under-the-skin injection. Both treatments are approved for use in several myeloma treatment regimens.
Medicare analysis compares outcomes in 2,382 myeloma patients
Clinical trials often have strict rules about who can participate, so their findings may not fully reflect what happens in everyday care. This is particularly relevant for older patients, who may have other health conditions that complicate treatment.
In this study, scientists used Medicare data to compare outcomes among 1,191 myeloma patients who received treatment with Darzalex Faspro and an equal number who received Darzalex. The researchers used a statistical technique called propensity score matching to make the groups as similar as possible based on characteristics recorded before treatment began. They then used statistical models to compare outcomes, including survival.
“Real-world evidence has previously been used to demonstrate treatment effect in oncology patients, including those with [myeloma], that may not be observed in randomized clinical trials of limited sample size, and to examine the effect of treatment in patients with different demographics or who do not satisfy the rigorous eligibility criteria of randomized clinical trials,” the researchers wrote.
“To our knowledge, our study is the first to use Medicare … claims data to compare overall survival between [Darzalex Faspro and Darzalex] in patients with” myeloma, the team noted.
Darzalex Faspro was associated with a 24% lower risk of all-cause mortality compared with Darzalex. The difference was statistically significant.
The survival difference did not appear to reflect differences in how well the treatments controlled the cancer. Exploratory measures, including time to another treatment, time to relapse or another treatment, and time to new myeloma-related organ damage, showed no statistically significant differences between the groups. Instead, researchers pointed to longer treatment duration and fewer serious infections with Darzalex Faspro as possible explanations for the survival findings.
Fewer treatment discontinuations and serious infections
Darzalex Faspro was associated with a 28% lower risk of treatment discontinuation compared with Darzalex. Patients receiving Darzalex Faspro also had a statistically significant 13% lower risk of serious infections.
“In Medicare patients with [myeloma], [Darzalex Faspro] was associated with improved [overall survival] compared with [Darzalex]. This difference appears to be driven by a lower risk of serious infections and longer treatment duration with” Darzalex Faspro, the researchers concluded.
The researchers noted that the study relied on insurance records, which lack some important clinical details. Other differences between the patient groups may also have influenced the results, despite the researchers’ statistical adjustments.
“Additional studies using alternative data sources would be valuable to confirm these results and more fully explore the differences and relationships between severe infections, duration of treatment, and [overall survival] due to the daratumumab [route of administration],” the scientists wrote.
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