Results have been announced for the Phase 1/2 MonumenTAL-1 study of talquetamab, an investigational, off-the-shelf (ready to use), bispecific T-cell engager antibody.

Talquetamab targets both GPRC5D, a novel target on multiple myeloma cells, and CD3 on T cells, activating the body’s immune system to fight this blood cancer.

Results from the study suggest patients with relapsed or refractory multiple myeloma who received a median of five prior lines of therapy, including a proteasome inhibitor, an immunomodulatory agent, and an anti-CD38 antibody, achieved overall response rates (ORR) of 74.1 percent and 73.1 percent with subcutaneously (SC) administered recommended Phase 2 doses (RP2Ds) of 0.4 mg/kg weekly and 0.8 mg/kg every two weeks, respectively, with a median duration of response (DOR) of nine months or longer.2 Data from this investigational trial were featured during the American Society of Hematology (ASH) Annual Meeting as an oral presentation and highlighted in an ASH press briefing on Saturday, December 10, 2022 (Abstract #157).

“The responses observed in the MonumenTAL-1 study suggest the clinical potential of talquetamab in the treatment of many patients who are triple-class refractory,” said Ajai Chari, M.D., Professor of Medicine, Hematology and Medical Oncology, Icahn School of Medicine, Mount Sinai, and principal study investigator.

“The results of this study indicate the potential of this treatment for heavily pretreated patients who have exhausted currently approved therapies.”

Results from the Phase 1 portion of the MonumenTAL-1 study were also published in The New England Journal of Medicine on December 10, 2022.

The ORR to talquetamab treatment was similar across both dose schedules.

With a median follow-up of 14.9 months (range 0.5+ to 29.0), 74.1 percent of patients treated at the SC 0.4 mg/kg dose administered weekly (QW) achieved a response, 59.4 percent achieved a very good partial response (VGPR) or better, 33.6 percent achieved a complete response (CR) or better and 23.8 percent achieved a stringent complete response (sCR).

The median progression free survival (PFS) was 7.5 months (95 percent CI, 5.7–9.4) at the 0.4 mg/kg QW dose.

At the SC 0.8 mg/kg dose administered every two weeks (Q2W), 73.1 percent of patients achieved a response, 57.2 percent achieved a VGPR or better, 32.4 percent achieved a CR or better, and 20 percent achieved a sCR at a median follow-up of 8.6 months (range 0.2 to 22.5).

Due to shorter follow-up in the 0.8 mg/kg Q2W dose cohort, the median PFS is not yet mature.2 Median DOR was nine months or longer in all groups, and longer DOR was observed in those patients who achieved a CR or better.

There were no significant differences in ORR in subgroup analysis including prior lines of therapy, refractoriness to prior therapy and cytogenetic risk at baseline.

“These data represent the importance of engaging T cells via CD3 and targeting GPRC5D – a tumor associated antigen which is overexpressed in multiple myeloma cells – for the treatment of patients with relapsed or refractory disease,” said Sen Zhuang, M.D., Ph.D., Vice President, Clinical Research and Development, Janssen Research & Development, LLC.

“Following our recent Biologics License Application submission to the U.S. FDA, we look forward to working with the agency to make this available as a treatment option in the short term and continuing our longer-term investigations of talquetamab as we aim to develop additional options for patients with this complex blood cancer.” 

An additional cohort was studied to determine response to talquetamab at either dose schedule after previous T-cell redirection therapy, either a CAR-T or CD3 bispecific antibody. Patients in this cohort were younger, had a higher prevalence of high-risk cytogenetics, and had received a median of six prior lines of therapy (range, 3 to 15).

Among these patients, 70.6 percent received prior CAR-T-cell therapy and 35.3 percent received prior bispecific antibody therapy.

At a median follow-up of 11.8 months (range 1 to 25.4), 62.7 percent of patients with prior T-cell redirection therapy achieved a response.

An ORR of 72.2 percent (95 percent CI, 54.8–85.8) was observed in patients with prior CAR-T-cell therapy and 44.4 percent (95 percent CI, 21.5-69.2) in patients with prior bispecific antibody treatment.

The safety profile was comparable in patients with and without prior T-cell redirection therapy.

No new safety signals were identified with longer follow-up in Phase 1 or Phase 2 of the MonumenTAL-1 study.

The most common adverse events (AEs) at the SC 0.4 mg/kg QW dose were cytokine release syndrome (CRS) (79 percent; 2.1 percent grade 3/4), skin-related AEs (55.9 percent; all grade 1/2) and nail-related AEs (51.7 percent; all grade 1/2).

The most common AEs at the SC 0.8 mg/kg Q2W dose were CRS (72.4 percent; 0.7 percent grade 3/4), skin-related AEs (67.6 percent; 0.7 percent grade 3/4) and dysgeusia (46.2 percent; not applicable).

CRS incidents were mostly grade 1/2 and largely confined to the step-up doses and first full dose.

The incidence of infection was 57.3 percent at the SC 0.4 mg/kg QW dose and 50.3 percent at the SC 0.8 mg/kg Q2W dose, with 16.8 percent and 11.7 percent grade 3 or higher, respectively.2 One patient in each dose cohort died due to COVID-19 infection.

Most high-grade hematologic AEs were cytopenias, which were generally limited to the first few cycles of treatment.2 Neutropenia was observed in 34.3 percent of patients treated at the SC 0.4 mg/kg QW dose (30.8 percent grade 3/4) and 28.3 percent of patients treated at the SC 0.8 mg/kg Q2W dose (22.1 percent grade 3/4).

Thrombocytopenia was observed in 27.3 percent of patients treated at the SC 0.4 mg/kg QW dose (20.3 percent grade 3/4) and 26.9 percent of patients treated at the SC 0.8 mg/kg Q2W dose (16.6 percent grade 3/4).2 At the SC 0.4 mg/kg QW dose, 4.9  percent of patients discontinued treatment due to AEs; 8.4 percent had dose delays and 14.7 percent had dose reductions.

At the SC 0.8 mg/kg Q2W dose, 6.2 percent of patients discontinued treatment due to AEs; 13.8 percent had dose delays and 6.2 percent had dose reductions.

Source: Janssen