Novel PET Assessment of Response to Daratumumab Quadruplet in Multiple Myeloma
Posted: Wednesday, January 12, 2022
After treatment of multiple myeloma, patients may appear to have no measurable residual disease (MRD) in the bone marrow, based on analysis of marrow aspirates. If myeloma persists outside the aspiration site, it may be detected with positron-emission tomography–computed tomography (PET-CT) based on F-fluorodeoxyglucose (FDG)—but some lesions are not FDG-avid and can be missed. However, reported Chor-Sang Chim, MD, of the University of Hong Kong in Pokfulam, and colleagues, 11C-acetate may prove to be a more sensitive and specific tracer for this purpose. In Therapeutic Advances in Hematology, they discussed its use in three cases.
The three patients were newly diagnosed with multiple myeloma and treated with a daratumumab-based quadruplet induction regimen. The deep responses of all three were ascertained with 11C-acetate PET (imaging complete response) as well as with conventional immunofixation (complete response) and next-generation sequencing (MRD-negative complete response).
Daratumumab-based quadruplets have a backbone of bortezomib, thalidomide, and dexamethasone or bortezomib, lenalidomide, and dexamethasone, the investigators noted. In most clinical trials, the daratumumab has been given weekly during induction. In these cases, though, the patients received the anti-CD38 monoclonal antibody once every 3 weeks.
What’s more, pointed out Dr. Chim and his team, two of the three patients (patients 1 and 3) harbored ultra-high–risk cytogenetics [t(4;14) plus TP53 del or gain (1q21)]. Patient 1 was a man diagnosed at age 63 with stage III disease; patient 2 was a woman diagnosed at age 60 with stage II disease; and patient 3 was a man diagnosed at age 73 with stage I disease. All patients had, at the time of writing, maintained their complete responses for 17, 12, and 30 months since diagnosis, respectively.
In multiple myeloma, “depth of response is highly prognostic of survival,” the researchers stated. Moreover, “MRD negativity has been shown to confer superior progression-free survival.”
Disclosure: The study authors reported no conflicts of interest.