Investigational Drug
Obrixtamig (BI 764532) is an investigational IgG‑like, DLL3×CD3 T‑cell–engaging bispecific antibody being developed for DLL3‑positive small cell lung cancer (SCLC) and other high‑grade neuroendocrine carcinomas (NECs). Early clinical studies report antitumor activity with a predominantly cytokine‑release‑syndrome (CRS)–centric safety profile. Multiple phase 1/2 studies are ongoing, including monotherapy, first‑line combinations, and combination with single‑agent chemotherapy. (ascopubs.org)
DLL3 is aberrantly expressed on many SCLC and poorly differentiated NECs but with minimal expression in normal adult tissues. Obrixtamig binds DLL3 on tumor cells and CD3 on T cells, forming an immunologic synapse that redirects T‑cell cytotoxicity against DLL3‑expressing cells. Preclinical work showed selective killing of DLL3‑positive cells and tumor regression in human T‑cell–engrafted models. (aacrjournals.org)
Note: Response assessments in phase 1 were investigator‑assessed per RECIST v1.1 and reflect heavily pretreated populations. Trials remain ongoing. (ascopubs.org)
The most frequent treatment‑related adverse event is CRS, typically grade 1–2 and occurring early during treatment; high‑grade CRS has been uncommon. Other common events include pyrexia, asthenia/fatigue, dysgeusia, and decreased lymphocyte counts. Reported phase 1 safety summaries include: - SCLC‑focused analysis: any‑grade CRS 53% (grade ≥3: 2%); other AEs included asthenia (26%/2% grade ≥3), lymphopenia (21%/19%), nausea (17%), pyrexia (17%). Step‑in dosing and standard CRS management (supportive care, corticosteroids, anti‑IL‑6R) were used. (jto.org) - epNEC cohort (ESMO 2023): any‑grade CRS 72% (grade ≥3: 4%); no treatment discontinuations due to treatment‑related AEs were reported in this abstract. (oncologypro.esmo.org)
Across early studies, dose‑limiting toxicities have been infrequent, and the maximum tolerated dose had not been reached at the time of the reported analyses. (jto.org)
Designations: FDA Fast Track designations have been announced for ES‑SCLC after ≥2 prior lines, epNEC after ≥1 prior line, and LCNEC of the lung; FDA Orphan Drug designation has been announced for SCLC. (Company/partner communications.) (globenewswire.com)
Clinical trial identifiers: NCT04429087; NCT05882058 (DAREON‑5); NCT06077500 (DAREON‑8). (ascopubs.org)
Terminology: International Nonproprietary Name (INN) obrixtamig; also referenced as OBT‑620 in partner materials. (drugs.ncats.io)
Last updated: Oct 2025
Found 4 active trials using this drug:
HealthScout AI summary: Adults with relapsed/refractory extensive-stage SCLC after platinum (and prior PD-1/PD-L1 if given) eligible for single-agent chemotherapy receive IV BI 764532, a DLL3×CD3 bispecific T‑cell engager, combined with chemotherapy (dose escalation) and then with topotecan (dose confirmation). Key exclusions include active/untreated brain mets and prior DLL3-directed T-cell therapies.
ClinicalTrials.gov ID: NCT05990738
HealthScout AI summary: Adults with recurrent/progressive diffuse glioma that is DLL3-positive by central IHC after standard therapy receive BI 764532 monotherapy as intravenous infusions in a single-arm dose-escalation setting. BI 764532 is a DLL3×CD3 bispecific T‑cell engager redirecting T cells to DLL3-expressing tumor cells; key exclusions include leptomeningeal/extracranial disease, prior DLL3‑directed therapy, and recent anti‑VEGF agents.
ClinicalTrials.gov ID: NCT05916313
HealthScout AI summary: Adults with relapsed/refractory extensive-stage SCLC (post ≥2 lines including platinum and, where standard, PD‑L1 inhibitor) or other high‑grade neuroendocrine carcinomas (including pulmonary LCNEC and DLL3‑high extrapulmonary NEC after ≥1 platinum) receive intravenous BI 764532, a DLL3/CD3 bispecific T‑cell engager redirecting T‑cell cytotoxicity to DLL3‑expressing tumors. Part 1 randomizes between two dose levels; Part 2 expands at the selected dose in centrally confirmed DLL3‑high extrapulmonary NEC.
ClinicalTrials.gov ID: NCT05882058
HealthScout AI summary: This trial enrolls adults with advanced, DLL3-positive small cell lung cancer, large cell neuroendocrine lung carcinoma, or neuroendocrine carcinoma of any origin who have progressed after standard therapies, to receive BI 764532—a parenterally administered DLL3/CD3 bispecific T-cell engager antibody. Eligible patients must have good performance status and adequate organ function, and may include those with treated or stable brain metastases.
ClinicalTrials.gov ID: NCT04429087