Promising Safety and Efficacy Signals from a Small Phase 1 Pilot Study (PRIMETIME) with RRx-001 + Opdivo® [nivolumab] in Traditionally Checkpoint Inhibitor Non-Responsive Tumors

Mar 15, 2023

  • The combination of RRx-001 + Opdivo was well tolerated
  • PRIMETIME was a small, duration-limited pilot study with an encouraging but preliminary anticancer signal in cold, non-immunogenic tumors

TORREY PINES, Calif., March 15, 2023 /PRNewswire/ — EpicentRx, a leading edge, clinical stage biopharmaceutical company, announced publication of results in the well-respected, international journal, Frontiers in Immunology, from a small 12 patient, 12-week, open label Phase 1 clinical trial called PRIMETIME (NCT02518958).

PRIMETIME was a pilot study to evaluate the safety of RRx-001 and nivolumab in patients with advanced checkpoint inhibitor non-responsive tumors and no standard options. RRx-001 reprograms tumor associated macrophages (TAMs), which normally aid, and abet cancer cells, to go on the attack against them. The presence of TAMs in tumors is responsible for resistance to the anticancer effects of checkpoint inhibitors like nivolumab. This was the basis to combine RRx-001 and nivolumab since the addition of RRx-001 may drive efficacy in tumor types where checkpoint blockade monotherapy is traditionally ineffective.

The combination treatment was well tolerated with no dose limiting toxicities and demonstrated an unconfirmed response rate of 25% and a disease control rate of 67% across four different dose levels in 12 heavily pre-treated patients with non-immunogenic tumor types. The main side effect due to RRx-001 was infusion related discomfort (33%). The main “side effect” from the combination of RRx-001 and nivolumab, which is probably not really a side effect at all, was pseudoprogression (25%). This describes an apparent increase of tumor size on imaging due to immune cell infiltration in the absence of actual tumor progression.

Dr. Tony Reid, EpicentRx CEO and manuscript lead author, commented that “this was a 12 patient, limited duration study so the usual caveats apply with such a small sample size that was treated for such a short time. However, checkpoint inhibitors are only beneficial in a small subset of patients with particular tumor types like melanoma. In other so-called “cold” tumor types like pancreatic and prostate they aren’t effective at all. Because RRx-001 revs up TAMs to attack tumor cells, it may succeed where other drugs have not to sensitize these otherwise poorly immune checkpoint sensitive cancers, which is exciting.”

About RRx-001
The lead EpicentRx small molecule, RRx-001 is a highly selective NLRP3 inhibitor with vascular normalization and tumor associated macrophage polarization properties that resensitizes tumors to previously administered therapies. RRx-001 is under investigation in a Phase 3 trial for the treatment of small cell lung cancer (SCLC), and in a Phase 2 trial for protection against oral mucositis in first line head and neck cancer. It is also under development as a treatment for neurodegenerative diseases like Parkinson’s and ALS/MND.

About EpicentRx, Inc.
EpicentRx is a leading-edge clinical-stage biopharmaceutical company with a complementary pipeline of small molecules, novel drug delivery devices, and cancer selective virus platforms that target inflammatory diseases of significant unmet need.

SOURCE EpicentRx, Inc.