{"entity":{"id":"gtb-5550","kind":"drug","name":"GTB-5550","aka":["GTB-5550 TriKE"],"tldr":"GTB-5550 is a protein from GT Biopharma, given as an injection under the skin, that wakes up natural killer cells and points them at tumour cells carrying the B7-H3 marker. It is in a first trial in several solid tumours.","summary":"GTB-5550 is GT Biopharma's dual-nanobody TriKE against B7-H3. Its phase 1 basket trial (NCT07541573) dosed the first patient in May 2026; up to six dose levels are tested before expansion cohorts in castration-resistant prostate, ovarian, breast, head and neck, non-small cell lung, pancreatic and bladder cancer. In September 2026 the company announced multiple myeloma as a potential further indication.","status":"phase-1","asOf":"2026-11-04","links":[{"label":"GT Biopharma: product pipeline","url":"https://www.gtbiopharma.com/product-pipeline/overview"},{"label":"ClinicalTrials.gov: NCT07541573","url":"https://clinicaltrials.gov/study/NCT07541573"}],"tags":["pipeline"],"related":[],"cancers":[],"sections":[],"technologies":["nk-cell-engagers"],"targets":["b7h3"],"drugs":[],"companies":["gt-biopharma"],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"provenance":{"editedBy":"OnCo startup monitors","editedOn":"2026-11-04"},"code":"GTB-5550","modality":"Tri-specific natural killer cell engager (dual camelid nanobody, subcutaneous)","mechanism":"A single-chain fusion of a camelid nanobody against CD16 on natural killer cells, wild-type IL-15, and a camelid nanobody against B7-H3 on tumour cells, as described by GT Biopharma.","approvals":[],"mechanismSteps":[],"toxicity":[],"access":[],"regulatoryEvents":[]},"route":"/drugs/gtb-5550/","neighbours":{"technology":[{"id":"nk-cell-engagers","kind":"technology","name":"NK cell engagers","route":"/technologies/nk-cell-engagers/"}],"target":[{"id":"b7h3","kind":"target","name":"B7-H3","route":"/targets/b7h3/"}],"company":[{"id":"gt-biopharma","kind":"company","name":"GT Biopharma","route":"/companies/gt-biopharma/"}]}}