Protalix’ oral anti-TNF drug hits the mark in phase 2 ulcerative colitis trial

Protalix' ProCellEx platform. (Image: Protalix.com)

Israeli biotech Protalix has completed the phase 2 trial of its anti-TNF drug OPRX-106 in ulcerative colitis (UC), backing up its potential as an oral alternative to current drugs in the class that have to be delivered via needles.

It’s a step forward for the program, which has been described by analysts at Jefferies as "binary"—i.e. with an equal risk of success or failure—simply because past experience has shown that oral delivery of protein-based drugs has been challenging. Protalix is evaluating a plant cell expression platform that is used to encapsulate the protein payload so it can pass unscathed through the digestive tract.

The biotech reported interim data from the first 16 evaluable patients with mild-to-moderate UC in the trial in January, prompting Jefferies to suggest that the data had demonstrated proof-of-concept for the oral delivery of biologics using the platform—albeit in a study without a control arm.

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Now, it has data in hand on 24 patients from the trial and says the drug achieved a 67% overall clinical response rate, with 28% of patients going into clinical remission over the eight-week study period. There was also significant improvement in other symptoms such as rectal bleeding, and according to Protalix there was no evidence of antibody responses to the drug which could limit its effectiveness.

“We are very excited by these results,” said Protalix CEO Moshe Manor. “They demonstrate efficacy and a lack of immunogenicity together with a favorable safety profile, which could potentially overcome one of the most challenging drawbacks of current ulcerative colitis therapies administered via injection and infusion.” The TNF market is currently headed by AbbVie’s $16bn Humira (adalimumab) but includes several blockbuster brands.

Lead investigator Professor Yaron Ilan, M.D., of Hadassah Hebrew University Medical Center in Jerusalem said the oral route could also sidestep some of the systemic side effects of current TNF inhibitors, such as malignancies and opportunistic infections.

Protalix has reportedly received multiple overtures from companies interested in PRX-106 and the delivering technology underpinning the candidate, says Jefferies. If successful in further trials, The drug could potentially tap into a TNF blocker market valued at tens of billions of dollars a year.

Meanwhile, OPRX-106 is just one of a trio of drugs in clinical development at the Israeli biotech. Lead Fabry disease candidate PRX-102 (pegunigalsidase alfa) was awarded fast-track status by the FDA in January as it could offer less frequent dosing than other Fabry drugs on the market, and is on track for data read-out from three phase 3 trials next year. Last October the company signed a partnership deal with Chiesi for this program.

Following after is cystic fibrosis candidate AIR DNase (alidornase alfa), a potential rival to Genentech’s Pulmozyme (dornase alfa) in midstage testing, although Protalix has indicated it wants to sign a partner before it will take that project further.

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