Reolysin (pelareorep) is a virus-based investigative therapy being developed by Oncolytics Biotech to treat solid tumors and hematological malignancies, or cancers of the blood.

The oncolytic virus therapy was recently granted fast track designation by the U.S. Food and Drug Administration (FDA) as a potential treatment of metastatic breast cancer.  The FDA also designated Reolysin an orphan drug for its potential to treat two rarer forms of this disease, ovarian cancer and pancreatic cancer.

How Reolysin works

Reolysin consists of a proprietary variant of the reovirus — specifically, a shortened form of the Respiratory Enteric Orphan Virus — which is a naturally occurring virus that resides in the digestive or respiratory tract without producing any symptoms.

The treatment is administered as an injection into the bloodstream and works by inducing the immune system against cancer cells, with a goal of killing them.

Upon administration, Reolysin is designed to preferentially infect and replicate inside cancer cells, destroying them and releasing cancer cell proteins. The released proteins are recognized as foreign and promote an immune response against any remaining cancer cells.

Reolysin in clinical trials

Reolysin has been shown to be safe and active against several cancers when administered alone or in combination with other cancer therapies.

Breast cancer

The fast track designation given Reolysin in this cancer was based on results from the IND 213 trial (NCT01656538). This open-label, randomized Phase 2 study assessed the safety and efficacy of Reolysin in combination with the chemotherapy agent Taxol (paclitaxel) compared to Taxol alone, in 74 patients with metastatic breast cancer.

Although there was no difference in progression-free survival between the two treatments, the combination treatment showed a seven-month improvement in overall survival (from 10.4 months to 17.4 months). A subgroup of breast cancer patients with a certain genetic mutation, called the p53 mutation, lived twice as long (20.9 months) when treated with Reolysin and Taxol compared to those who received Taxol alone (10.4 months, on average). Similar results were observed in a subgroup of patients with what is known as hormone receptor double-positive, HER2-negative breast cancer. In these people, median overall survival more than doubled with the combination treatment compared to Taxol treatment alone (21.8 months versus 10.8 months).

Pancreatic cancer

A Phase 1b trial (NCT02620423), called the REO 024 study, enrolled patients with relapsed metastatic adenocarcinoma of the pancreas (MAP) whose disease had progressed after first-line treatment. Patients received Reolysin as an injection into their bloodstream in combination with Keytruda (pembrolizumab) and chemotherapy (Gemzar-gemcitabine, 5-fluorouracil, or Campto-irinotecan).

Results showed that the combination therapy was safe and demonstrated anti-tumor activity in these previously treated MAP patients.

Another open-label, randomized Phase 2 trial (NCT01280058), the NCI-8601 study, evaluated Reolysin in combination with carboplatin and Taxol in patients with metastatic pancreatic cancer. Trial results showed that the combination treatment improved long-term overall survival in the patients.

Multiple myeloma

An open-label Phase 1b trial (NCT02514382), also called the REO 019 study, assessed the safety and tolerability of Reolysin in combination with Velcade (bortezomib) and dexamethasone in patients with multiple myeloma that has returned or did not respond to treatment (relapsed or refractory cancer).

Preliminary results show the combination therapy was well-tolerated and induced an immune system response, leading to the death of myeloma cells in heavily pre-treated patients with multiple myeloma. The study is ongoing and currently recruiting eligible adults at its one test site in Los Angeles; information is available by clicking on the trial’s identification number. The study is expected to finish in 2019.

Another Phase 1 study (NCT02101944) involving adults with advanced multiple myeloma (relapsed or refractory) is now underway in Ohio, and currently recruiting. The safety, tolerability and efficacy of Reolysin in combination with the chemotherapy Kyprolis (carfilzomib) and dexamethasone, a corticosteroid, is being evaluated in about 28 patients. Information on this trial, due to conclude in December 2018, is available by clicking on its identification number.

 Non-small cell lung cancer (NSCLC)

An open-label randomized Phase 2 trial (NCT01708993), called the IND 211 study, assessed the safety and efficacy of Reolysin in patients with advanced NSCLC. Reolysin was combined with Taxotere (docetaxel) or Alimta (pemetrexed), depending on a patient’s type of NSCLC.

The study showed that the combination was well-tolerated, with significant improvement in progression-free survival in female patients, especially, and those with EGFR (epidermal growth factor receptor) and p53 mutations.

Other cancers

Reolysin is also being studied in other cancers, including ovarian cancer (NCT01199263) and colorectal cancer (NCT01274624).


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