Abstract CT052: A phase 1/2 randomized study of imvotamab monotherapy and in combination with loncastuximab tesirine in relapsed/refractory non-Hodgkin lymphomas

Background: Recent advances in the treatment of non-Hodgkin lymphoma (NHL) have transformed the landscape and provided significant benefits to patients. Novel agents that target CD19 and CD20 on B cells, such as bispecific T-cell engagers and chimeric antigen receptor T-cell (CAR-T) therapy, have demonstrated benefit for patients in the relapsed and refractory setting. However, these agents can often be associated with significant toxicity and there is a need for new therapies that can provide clinical benefit with a superior safety profile. Imvotamab is a novel CD20 x CD3 bispecific antibody utilizing an IgM backbone. This allows targeting of up to 10 CD20 binding sites for every CD3 site. In preclinical models, imvotamab demonstrated encouraging antitumor activity and stimulated T-cells in a more physiologic manner than IgG-based antibodies, which may reduce adverse events typically associated with T-cell engagers and CAR-T, such as CRS and neurotoxicity. Loncastuximab tesirine is a CD19-targeting antibody-drug conjugate approved by the US FDA and EMA for relapsed DLBCL after 2 lines of systemic therapy. Loncastuximab tesirine has shown activity in both DLBCL and FL. Combining therapies such as loncastuximab tesirine, which targets CD19 and induce apoptosis of cancer cells, with imvotamab’s ability to eliminate CD20+ tumor cells by engagement with T-cells, may improve treatment outcomes among patients with NHL via synergistic mechanisms of action. Methods: This study is a Phase 1/2, multicenter, single-arm clinical trial of imvotamab as monotherapy and in combination with loncastuximab tesirine for patients with relapsed/refractory NHL. Phase 1a Dose Escalation is complete with no DLTs or neurotoxicity AEs up to 1000mg dose titration. Phase 1b Combination will evaluate imvotamab and loncastuximab tesirine in patients with R/R 2nd line or later NHL. Phase 2 monotherapy Dose Selection is currently ongoing. The Phase 2 component randomizes patients at two different dose levels (100 mg and 300 mg plateau dose) in two separate indications (R/R DLBCL and R/R FL). Patients receive weekly dosing on Day 1, 8, and 15 of each 21- day cycle. Dosing begins at 15 mg and is increased weekly for 3-4 weeks to reach the plateau dose. Patients then stay at the plateau dose until disease progression or unacceptable toxicity. Patients who achieve a response by Week 12 may switch to a less frequent dosing interval of every 3 weeks. Primary endpoints include frequency and severity of adverse events and objective response rate (ORR) based on Lugano criteria. Correlative biomarker studies will evaluate the relationship of clinical benefit with blood and tissue biomarkers. The study is currently open with patients enrolling in Phase 2 at time of submission. Phase 1b Combination is expected to begin enrollment in the first quarter of 2023. Clinical trial information: NCT04082936. Citation Format: Catherine Diefenbach, Won Seog Kim, Chan Cheah, Ajay K. Gopal, Philippe Armand, Ian Flinn, Gareth P. Gregory, Sung-Soo Yoon, Loretta Nastoupil, Jennifer Lue, Vincent Ribrag, Javier Briones, Antonio Salar-Silvestre, Anna Sureda-Balari, Matthew Ku, Hans Cruz, Paul Thaler, Ibrahim Qazi, Rachel Wei, Maya Leabman, Genevive Hernandez, Iris Sison, Elizabeth Budde. A phase 1/2 randomized study of imvotamab monotherapy and in combination with loncastuximab tesirine in relapsed/refractory non-Hodgkin lymphomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT052.