On October 29, 2017 Rgenix, Inc., a clinical stage biopharmaceutical company developing first-in-class small molecule and antibody can, cer therapeutics, reported preliminary data from an ongoing Phase 1a/b clinical trial with its lead oral investigational agent, RGX-104 (Press release, Rgenix, OCT 29, 2017, View Source [SID1234521283]). These data demonstrate immune-stimulatory activity in solid tumor patients with highly-refractory malignancies, including patients who have failed prior checkpoint inhibitors. Also presented were pre-clinical data establishing the immune-modulatory and anti-tumor effects of RGX-104. The company presented the data at the AACR (Free AACR Whitepaper)-NCI-EORTC AACR-NCI-EORTC (Free AACR-NCI-EORTC Whitepaper) International Conference on Molecular Targets and Cancer Therapeutics (EORTC-NCI-AACR) (Free ASGCT Whitepaper) (Free EORTC-NCI-AACR Whitepaper) in Philadelphia.
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RGX-104 is a liver X receptor (LXR) agonist that upregulates the expression of the target gene, Apolipoprotein E (ApoE), triggering several downstream effects via ApoE receptors. In pre-clinical data presented today, treatment with RGX-104 in mouse models resulted in dual effects on myeloid-derived suppressor cells (MDSCs) and dendritic cells (DCs), both innate immune cells that play a central role in regulating anti-tumor immunity and response to checkpoint inhibitors. Innate immune activation with RGX-104, coupled with a reduction in tumor blood vessels, resulted in anti-tumor activity as a monotherapy as well as synergy with checkpoint inhibitors (CPI) in several drug-resistant mouse models. These data provide rationale for Rgenix’s ongoing Phase 1a/b trial of RGX-104 in advanced cancer patients and support evaluation of RGX-104 as both a monotherapy as well as in combination with CPIs.
As part of the ongoing Phase 1a/b clinical trial, 15 patients with a variety of solid tumors have been treated with escalating doses of RGX-104 monotherapy. Patients treated with RGX-104 had a median of six prior therapies with a range of 1-12, highlighting a population of patients with profoundly resistant disease.
Activation of the LXR-ApoE pathway with oral administration of RGX-104 was associated with immune-stimulatory activity in 9 of 10 evaluable patients. This was demonstrated by an increase (up to 11-fold) in activated circulating PD-1+CD8+ T cells during treatment. T cell activation was observed in patients who experienced modulation of the innate immune system during treatment. The effect of RGX-104 on the innate immune system consisted of both MDSC depletion (up to 95% decrease) as well as DC activation as indicated by induction of PD-L1 expression (up to 100% increase). In most cases these effects were observed within two weeks of treatment initiation and generally preceded the onset of T cell activation.
Safety data demonstrate good tolerability with on-target safety findings in the first three dosing cohorts. One patient experienced a DLT of grade 4 reversible neutropenia – a known potential effect of LXR agonism – that reversed within one week, allowing the patient to subsequently tolerate a 50% dose reduction. No MTD has been reached to date. Stable disease has been observed in 4 of 12 evaluable patients, including three who have failed prior checkpoint inhibitor therapy, for periods of at least 8 weeks.
“We are very pleased to see robust evidence of immune stimulation in such highly-pretreated patients,” said Roger Waltzman, MD, MBA, and Chief Medical Officer of Rgenix. “CPI therapy is now commonplace but only a minority of patients derive clinical benefit. We hope the effects of RGX-104 on modulating barriers to innate and adaptive immune function will enable a larger number of patients to benefit from this therapy. These preliminary results also highlight the potential for development of RGX-104 as a monotherapy.”
Rgenix plans to enroll subsequent dose-escalation cohorts of the RGX-104 monotherapy trial in Q4 2017. Additionally, Rgenix is planning to initiate the Phase 1b expansion component of the study, comprised of disease directed cohorts receiving RGX-104 monotherapy as well as cohorts receiving RGX-104 combined with a CPI, projected to begin in 1H 2018.
“These preliminary data establish RGX-104 as a potential first-in-class oral immunotherapy agent with broad immune-stimulatory activity and a unique dual mechanism targeting innate immunity,” said Masoud Tavazoie, MD, PhD, and Chief Executive Officer of Rgenix. “These results also further validate our discovery platform at Rgenix, as well as our pipeline of other drug candidates slated to begin entering clinical-stage development in 2018.”
The LXR-ApoE pathway was discovered as a cancer target using a microRNA (miRNA) based target discovery approach originally developed at The Rockefeller University and now exclusively licensed to Rgenix.