Compass Therapeutics Announces First Patient Dosed in Phase 1 Trial of CTX-471

CAMBRIDGE, Mass., July 8, 2019Compass Therapeutics, a clinical-stage biotechnology company targeting the human immune synapse with a new generation of monoclonal and multispecific antibody therapeutics, today announced the first patient has been dosed in its multi-center, open-label, first-in-human Phase 1 trial of CTX-471, a fully human monoclonal antibody that binds and activates a unique epitope of the co-stimulatory receptor CD137 expressed on T cells and NK cells. Enrollment in the trial is open to patients with metastatic or locally advanced solid cancers that have progressed while receiving an approved PD-1 or PD-L1 inhibitor for at least three months.

“The field of oncology is greatly in need of novel ways to engage the immune system to fight cancer beyond PD-1/PD-L1 checkpoint inhibitors. We currently have very limited options for treating patients in whom PD-1 or PD-L1 inhibitors fail,” said F. Stephen Hodi, MD, a member of the Compass Scientific Advisory Board, director of the Melanoma Center and the Center for Immuno-Oncology at Dana-Farber/Brigham and Women’s Cancer Center, and professor of medicine at Harvard Medical School.

The study is a multiple ascending dose (MAD) study with the potential for a dose expansion phase. The primary objective of the MAD portion of the study is to assess the safety and tolerability of CTX-471 monotherapy at various doses. The dose expansion stage will then evaluate a larger cohort of patients to determine an optimized dose for the future Phase 2 studies. Secondary endpoints will include measures of overall response rate and progression- free survival, among others.

“We are immensely gratified to have reached this milestone to begin to bring this treatment to patients,” said Thomas Schuetz, MD, PhD, the scientific founder and chief executive officer of Compass. “We believe CTX-471 has the potential to be a best-in-class CD137 agonist due to its very promising preclinical data, which include the total eradication of established tumors in syngeneic mouse models and the generation of long-term, functional immunological memory in these models.”

Further information is available at https://clinicaltrials.gov/ct2/show/NCT03881488

About CTX-471

CTX-471 is a fully human monoclonal antibody that binds and activates a novel epitope of the co-stimulatory receptor CD137, also known as 4-1BB, a member of the tumor necrosis factor receptor superfamily. CTX-471 has demonstrated potent monotherapy activity against multiple syngeneic tumor models including the generation of long-term functional immunological memory. Most notably, CTX-471 shows a unique ability to completely eradicate large, established tumors where other preclinical CD137 antibodies and antibodies against PD-1, PD-L1, CTLA-4 and OX40 have minimal effects in these models. In contrast to other CD137 antibodies, CTX-471 shows no evidence of hepatic toxicity in both mice and non-human primates, supporting the potential for a wide therapeutic window in patients.

About Compass Therapeutics

Compass Therapeutics is a clinical-stage biotechnology company targeting the human immune synapse with a new generation of monoclonal and multispecific antibody therapeutics. Compass has broadly drugged the immune system by generating epitopically diverse antibody panels to more than 40 targets across all immune cell types and is leveraging its proprietary StitchMabsTMand common light-chain based multispecific platforms to empirically identify combinations and multispecifics with optimized activity. The company’s lead product candidate, CTX-471, is a fully human agonistic antibody of CD137, which is in a Phase 1 study in patients with inadequate responses to PD-1/PD-L1 checkpoint inhibitors. Compass is also progressing several preclinical assets including a novel class of NK cell engaging bispecifics targeting NKp30 and multiple bispecific checkpoint programs. The company’s offices and labs are based in Kendall Square in Cambridge, Mass.

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