RX-3117

A Targeted Anti-Cancer Therapy

RX-3117 is a novel, oral, small molecule nucleoside prodrug which is activated (phosphorylated) by UCK2 which is predominantly expressed in cancer cells. Once activated, it is incorporated into the DNA or RNA of cancer cells inducing apoptotic cell death. Because UCK2 is overexpressed in multiple human tumors but has a very limited presence in normal tissues, RX-3117 offers the potential for a targeted anti-cancer therapy with an improved efficacy and safety profile relative to other nucleoside analogues. RX-3117 has been shown to have efficacy in preclinical models and in clinical trials against tumors that have developed resistance to other nucleoside analogues such as gemcitabine. RX-3117 has therapeutic potential in a broad range of cancers, including pancreatic, bladder, colon, and lung cancer. RX-3117 has received "orphan drug designation" for pancreatic cancer from the U.S. Food and Drug Administration (FDA) and from the European Commission (EC).

Candidate & Indication Collaborators Preclinical Phase 1 Phase 2

RX-3117

Metastatic Pancreatic Cancer

Advanced Bladder Cancer

Additional Cancer Indications

BioSense
Preclinical complete
Preclinical complete
Preclinical in progress
Phase 1 complete
Phase 1 complete
Phase 1 not started
Phase 2 in progress
Phase 2 in progress
Phase 2 not started

RX-3117 Mechanism of Action

Normal cells and tumor cells contain various kinases that phosphorylate and modulate the activities of proteins, peptides and nucleosides. One of these kinases, uridine-cytidine kinase 2 (UCK2) is expressed only in cancer cells and minimally in normal tissue. RX-3117 is activated by the UCK2 found in the cancer cells.

Inside the cancer cell, inactive RX-3117 is transported across the cell membrane and is activated by UCK2 in the cytoplasm.

Activated RX-3117 crosses nuclear membrane and is incorporated into both RNA and DNA.

Cancer cells undergo apoptosis while normal cells are unaffected.

Taking Action Against Bladder and Pancreatic Cancer

~55K

Estimated new cases of pancreatic cancer in the U.S. in 20181

~44K

Estimated deaths in the U.S. due to pancreatic cancer in 20181

~81K

Estimated new cases of bladder cancer in the U.S. in 20182

~17K

Estimated deaths in the U.S. due to bladder cancer in 20182

1 National Cancer Institute  

2 American Cancer Society

Clinical Development

Metastatic Pancreatic Cancer

Rexahn completed a Phase 2a clinical trial of RX-3117 in patients with relapsed or refractory pancreatic cancer. The final data were presented at the American Society of Clinical Oncology Gastrointestinal Cancers (ASCO GI) 2018 Annual Meeting. The Phase 2a clinical trial was a multicenter, open-label single-agent study of RX-3117 conducted at 8 clinical centers in the United States. Patients in the trial received a 700 mg daily oral dose of RX-3117, five times weekly for three weeks in a 28-day cycle for up to eight treatment cycles, or until their disease progressed. A total of 46 patients with metastatic pancreatic cancer were enrolled in the study. Seventy-eight percent of the patients had received two or more prior cytotoxic therapies and 93% of the patients had progressed after receiving gemcitabine therapy.

Forty-three patients were included in the final efficacy analysis. Of these, 31% of patients had an increase in progression-free survival for two months or more and five patients(12%) had disease stabilization for greater than four months. One patient who had three prior treatments for metastatic pancreatic cancer (including gemcitabine) had a partial response (≥ 30% reduction in total tumor volume.

A Phase 2 clinical proof-of-concept study of RX-3117 in combination with Abraxane® (nab-paclitaxel) in first-line metastatic pancreatic patients is ongoing. The study is an open-label evaluation of the safety and efficacy of RX-3117 in combination with Abraxane in patients who have had no prior chemotherapies. The study is a two-stage study. The first stage is designed to determine the optimum dose of RX-3117 and Abraxane to be evaluated in the second stage. Preliminary data were presented in a poster presentation at the 5th NCI Pancreatic Cancer Symposium held October 2-3, 2018 at the National Institutes of Health in Bethesda, Maryland. Combined administration of RX-3117 and Abraxane in newly diagnosed pancreatic cancer patients appeared to be safe and well-tolerated. The most common (≥20%) adverse events were diarrhea, nausea, fatigue, alopecia, anorexia and rash and there were no dose-limiting toxicities. The combination demonstrated preliminary efficacy in newly diagnosed metastatic pancreatic cancer patients. Of the 14 subjects that had at least one on-study scan (after 2 cycles of therapy), one patient experienced a complete response (CR) after 6 cycles of therapy and three patients exhibited a partial response (PR): two after 2 cycles (39-47% tumor reductions) and one after 4 cycles of therapy (36% tumor reduction). An additional eight patients experienced stable disease (SD) for at least 2 cycles with tumor marker (CA19-9) reductions of 43-69%. The disease control rate (CR+PR+SD) for evaluable patients was 86% and the overall response rate (CR+PR) was 29%.

Advanced Bladder Cancer

Rexahn initiated a Phase 2a clinical trial in advanced bladder cancer. The clinical trial is a multicenter, open-label single-agent study of RX-3117 being conducted at 5 clinical centers in the United States. RX-3117 is being administered orally five times weekly. Interim data were presented at the American Society of Clinical Oncology Genitourinary Cancers (ASCO GU) in 2018.

A total of 27 patients with advanced bladder cancer were enrolled in the study. Patients in the study had actively progressing bladder cancer with distant metastases to multiple sites including the liver, lung, lymph nodes and pelvis. Eighty-seven percent of the patients had received two or more prior therapies including gemcitabine (85% of patients) and immunotherapy (67% of patients). Twenty-one patients were included in the efficacy analysis. Of these, 33% experienced progression-free survival for two months or more and four patients, or 19%, had disease stabilization for greater than four months with one of these patients having stable disease for 301 days. Four patients had a reduction in tumor size ≥ 15%. RX-3117 was safe and well tolerated. Enrollment in this trial is ongoing.

Clinical Trials

Newly Diagnosed Metastatic Pancreatic Cancer Clinical Trial

Stage 1 will be conducted as a dose-finding, open-label study of oral RX-3117 administered in combination with Abraxane® to subjects with metastatic pancreatic cancer. After completion of Stage 1 portion, a Phase 2a study will be conducted enrolling 40 patients.

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Advanced Bladder Cancer Clinical Trial

The purpose of this study is to determine the maximum tolerated dosage of RX-3117 in subjects with advanced or metastatic solid tumors (Phase 1). The purpose of the Phase 2 portion is to estimate anti-tumor activity in subjects with advanced malignancies (relapsed or refractory pancreatic or advanced bladder cancer).

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Publications

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