Related Experiment Video
Updated: Nov 21, 2025

Identification of Mediators of T-cell Receptor Signaling via the Screening of Chemical Inhibitor Libraries
Published on: January 22, 2019
RRx-001, a downregulator of the CD47- SIRPα checkpoint pathway, does not cause anemia or thrombocytopenia
Bryan Oronsky1, Pedro Cabrales2, Scott Caroen1
1Clinical Department, EpicentRx, Inc, La Jolla, CA, USA.
Abstract:
Introduction: The CD47 and SIRPα checkpoint pathway has garnered much interest within the anti-cancer research community, with multiple experimental checkpoint inhibitors targeting CD47 and SIRPα in development. The use of such checkpoint inhibitors may however be limited by hematologic toxicity.Areas covered: We report on RRx-001, the first known small molecule downregulator of CD47 and SIRPα, which has shown a lack of hematologic toxicity in clinical trials.Expert opinion: RRx-001 is the first reported small molecule downregulator of CD47 and SIRPα and lacks any notable hematologic or systemic toxicity as demonstrated in clinical trials to date. Small molecule RRx-001 could be used in combination with or in place of CD47 targeting antibodies for anti-cancer treatment.
Insights
RRx-001, a novel small molecule, downregulates the CD47 and SIRPα pathway without causing hematologic toxicity. This offers a safer alternative to antibody-based therapies for cancer treatment.
Area of Science:
- Immunology
- Oncology
- Pharmacology
Background:
- The CD47/SIRPα pathway is a key target in anti-cancer research.
- Existing CD47/SIRPα inhibitors may cause hematologic toxicity.
- There is a need for safer immunotherapies targeting this pathway.
Purpose of the Study:
- To introduce RRx-001 as a novel small molecule downregulator of CD47/SIRPα.
- To evaluate the safety profile of RRx-001, particularly regarding hematologic toxicity.
- To explore the potential of RRx-001 in cancer treatment.
Main Methods:
- Clinical trials were conducted to assess RRx-001.
- Hematologic toxicity was a primary safety endpoint.
- The study reports on the observed toxicity profile of RRx-001.
Main Results:
- RRx-001 demonstrated a lack of significant hematologic toxicity in clinical trials.
- No notable systemic toxicity was observed with RRx-001 treatment.
- RRx-001 functions as a small molecule downregulator of CD47 and SIRPα.
Conclusions:
- RRx-001 is the first small molecule found to downregulate CD47 and SIRPα.
- RRx-001 presents a favorable safety profile, lacking significant hematologic toxicity.
- RRx-001 may serve as a viable alternative or adjunct to CD47-targeting antibodies in cancer therapy.
More Related Videos
09:08Investigating Target Gene Function in a CD40 Agonistic Antibody-induced Colitis Model using CRISPR/Cas9-based Technologies
Published on: June 2, 2021
08:46A Real-time Potency Assay for Chimeric Antigen Receptor T Cells Targeting Solid and Hematological Cancer Cells
Published on: November 12, 2019
Related Concept Videos
Receptor Downregulation in MVBs
The EGFR can initiate signaling pathways that lead to cell proliferation, migration, and differentiation. Overexpression of EGFR stimulates cells to proliferate. Excessive EGFR...
Regulation of Hematopoietic Stem Cells
Regulation of the Unfolded Protein Response