“Talquetamab is a novel agent directed against a new antigen target in myeloma,” explained lead investigator Ajai Chari, MD, of Icahn School of Medicine at Mount Sinai in New York.
The product has demonstrated “a response rate of 73% to 74% with both weekly and every 2-week schedules in a heavily treated patient population. Even in those patients with prior T-cell redirection, we see a 63% response rate,” said Dr. Chari, who reported the data at the American Society of Hematology annual meeting.
It is encouraging to see high response rates among patients with disease that is refractory to multiple prior lines of therapy, and the results suggest that talquetamab may buy time for patients with few other options, said Stephanie Lee, MD, MPH, of the Fred Hutchinson Cancer Center in Seattle, and a former ASH president.
“It looks like there are responses even in people who are heavily pretreated and have had other agents similar to it, “ she said. “We hear about ‘penta-refractory’ [disease] and everything, and I think we’re going to start hearing about ‘octo-refractory’ and ‘deci-refractory,’ and those things. It’s really exciting [to see these responses],” she said. Dr. Lee moderated a media briefing prior to Dr. Chari’s discussion of the data.
Talquetamab is a bispecific antibody directed against a novel target with the prosaic name of “G protein–coupled receptor, family C, group 5, member D” or simply GPRC5D. The antigen is a so-called “orphan” receptor with an unidentified ligand. The receptor is expressed in malignant plasma cells, making it a particularly attractive target for the treatment of patients with multiple myeloma.
“It’s important to pick the right target for these [patients] and GPRC5D is a good candidate for that because it’s highly expressed on myeloma cells but spares normal tissues, in particular the hematopoietic stem cells for the precursors to their blood,” Dr. Chari said.
The new drug could be available next year. The manufacturer, Janssen, announced last week that it had submitted an approval application with the Food and Drug Administration for talquetamab use in the treatment of patients with relapsed or refractory multiple myeloma.
The clinical results so far “indicate the potential of this treatment for heavily pretreated patients who have exhausted currently approved therapies,” Dr. Chari said in a statement.
Dr. Chari and colleagues recently reported results of the phase 1 MonumenTAL-1 study in The New England Journal of Medicine. At ASH 2022, they reported phase 2 results from the same study, including some patients carried over from phase 1, but also a subgroup of patients with prior exposure to either chimeric antigen receptor T-cell (CAR-T) therapy or other bispecific T cell-engaging antibodies.
In the phase 1 dose-escalation study published in NEJM, the response rates among patients who had a median of six prior lines of therapy ranged from 64% to 70%. The drug was delivered in this phase at a variety of dose levels and schedules, and both intravenously and subcutaneously.