P-087: Real-World Clinical Outcomes of Teclistamab and Talquetamab in Relapsed/Refractory Multiple Myeloma (RRMM): A UK Single-Centre Experience

Introduction: Patients with RRMM have historically faced an adverse prognosis with limited alternatives. Recent advancements have introduced bispecific antibodies such as teclistamab and talquetamab as feasible options. These agents have shown an acceptable safety profile and have opened an encouraging path to address unmet treatment needs with promising rates of response and survival. However, there is still limited real-world data available on the clinical outcomes of these treatments



Methods: In this UK single-centre study, we conducted a retrospective review of 7 patients treated with teclistamab and 6 with talquetamab. All were part of the pre-approval access program, which made these drugs available in the UK from February 2022 to September 2023. Variables assessed included PFS, OS, ORR, very good partial response or better (≥VGPR), complete response or better (≥CR) and duration of response (DOR). We also evaluated common complications, such as CRS and haematological toxicity. These results were compared with data from the phase I/II MajesTEC-1 study and the phase I MonumenTAL-1 study. The main limitation of our study was the sample size.



Results: Our analysis of patients treated with teclistamab revealed response rates lower than those reported in the MajesTEC-1 study, with an ORR of 42% vs 63%. The consistency and durability of response were also lower in our study, with ≥VGPR at 42% vs 58.8%, ≥CR at 14% vs 39.4% and a median DOR of 8 months vs 18.43 months. CRS rate was similar and did not exceed grade 2. Haematological toxicity was below expected except for thrombocytopenia, which had a similar rate (43% vs 40%). Nonetheless, in our cohort poor prognosis features were more prevalent.

Regarding talquetamab, our data showed better response rates compared to the MonumenTAL-1 trial, with an ORR 100% vs 64%. These responses were more consistent and durable, with ≥VGPR at 50% vs 52%, ≥CR at 33% vs 23% and a median DOR that has not been reached yet after a median follow-up of 9 months compared to 7.8 months previously reported. The CRS rate was lower than expected (50% vs 80%), and never surpassed grade 2. Haematological toxicity was higher than reported for anaemia and thrombocytopenia (66% vs 43% and 50% vs 23%) while neutropenia rates were similar.

As additional findings, no discontinuations were related to AEs or drug intolerance and none of the reported deaths were associated with the use of any of the drugs.



Conclusions: Aligning with previous results, both agents were well-tolerated and showed manageable safety profiles. In terms of outcomes, in our experience teclistamab showed lower response rates and durability compared to trial data (possibly biased by the characteristics of our cohort), while talquetamab exhibited higher response rates and promising durability. These findings emphasize the importance of further real-world data with larger samples to overcome the main weakness of our study and obtain robust evidence to complement clinical trials and optimize strategies for RRMM.