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July 22, 2019
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Subcutaneous daratumumab attains deep response in multiple myeloma

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Saad Z. Usmani

A subcutaneous formulation of daratumumab exhibited similar pharmacokinetics as the standard IV formulation among patients with relapsed or refractory multiple myeloma, according to results from the phase 1B PAVO study published in Blood.

Perspective from Adam Binder, MD

The higher of the two doses evaluated induced deep, durable responses among patients with heavily pretreated disease.

Subcutaneous daratumumab (Darzalex, Janssen) also appeared associated with a lower rate of infusion-related reactions as the IV formulation, results showed.

Daratumumab, a human monoclonal antibody targeting CD38, is approved as monotherapy and in combination regimens for patients with multiple myeloma,” Saad Z. Usmani, MD, FACP, chief of plasma cell disorders and director of clinical research in hematologic malignancies at Levine Cancer Institute at Atrium Health, as well as a HemOnc Today Editorial Board Member, and colleagues wrote. “Currently, daratumumab is administered IV. The phase 1b PAVO study evaluated subcutaneously administered daratumumab in combination with the recombinant human hyaluronidase PH20 enzyme [for] patients with relapsed or refractory multiple myeloma.”

The first part of the open-label, multicenter dose-escalation study included 53 patients aged 18 years or older with measurable serum or urine M-protein levels and an ECOG performance status of 2 or less.

All study participants received at least two prior lines of treatment — including a proteasome inhibitor and an immunomodulatory drug — but had not received anti-CD38 therapy.

Patients received a mix-and-deliver formulation of daratumumab and recombinant human hyaluronidase PH20 enzyme administered via subcutaneous infusion.

Evaluated doses — based on the approved weekly 16-mg/kg IV dose for daratumumab — were 1,200 mg (n = 8; median age, 65.5 years) or 1,800 mg (n = 45; median age, 63 years).

Treatment was administered in 28-day cycles on the following schedule: once weekly in the first and second cycles; every 2 weeks in the third through sixth cycles; and then every 4 weeks until disease progression or unacceptable toxicity.

The most common treatment-emergent adverse events among patients who received the 1,200-mg dose were thrombocytopenia, upper respiratory tract infection, insomnia and decreased appetite (37.5% each).

The most common treatment-emergent adverse events among patients who received the 1,800-mg dose were anemia (33.3%), upper respiratory tract infection (26.7%), pyrexia (26.7%) and diarrhea (26.7%).

Infusion-related reactions occurred among one patient (12.%) in the 1,200-mg group and 11 patients (24.4%) in the 1,800-mg group. The majority of reactions were grade 1 or grade 2, and most occurred after the first infusion.

The 1,800-mg subcutaneous dose appeared associated with serum concentrations similar to or greater than those observed with the approved 16-mg/kg IV dose. Researchers reported overall response rates of 25% in the 1,200-mg group and 42.2% in the 1,800-mg group.

Many of the responses reported in the 1,800-mg group deepened over time. Ten patients achieved initial partial response; with further treatment, three subsequently achieved stringent complete response and four achieved very good partial response. Also, one patient in the 1,800-mg group who initially achieved very good partial response subsequently achieved a stringent complete response.

The second part of this study — which is ongoing — will evaluate the co-formulation of daratumumab and recombinant human hyaluronidase PH20 enzyme at the 1,800-mg dose.

“These findings show that subcutaneous administration of daratumumab is feasible [for] patients with multiple myeloma,” Usmani and colleagues wrote. “The 1,800-mg dose of [mix-and-deliver daratumumab plus recombinant human hyaluronidase PH20 enzyme] achieves pharmacokinetic concentrations similar to or greater than those following IV infusion of daratumumab 16 mg/kg, achieves deep and durable responses in patients with multiple myeloma, and has an acceptable safety profile with a low rate of infusion-related reactions.” – by Jennifer Byrne

 

Disclosures: Usmani reports consultant roles with, research funding from, speakers’ bureau roles with or travel expenses from AbbVie, Amgen/Onyx, Array BioPharma, Celgene, GlaxoSmithKline, Janssen, Merck, Pharmacyclics, Sanofi, Seattle Genetics, Skyline or Takeda/Millennium. Please see the study for all other authors’ relevant financial disclosures.