ST Pharm COVID-19 Vaccine Shows Increased Neutralizing Antibodies in Phase 1 Interim Results

ST Pharm has disclosed interim results from Phase 1 clinical trials of its COVID-19 messenger ribonucleic acid (mRNA) vaccine ‘STP2104,’ showing an increase in neutralizing antibody titers compared to before vaccination.

Booth views of Dong-A ST and ST Pharm set up at CPHI Worldwide 2023.
[Photo by Dong-A ST]

On the 14th, ST Pharm announced that it received these interim Phase 1 clinical trial results from the National Institute of Infectious Diseases at the Korea National Institute of Health. STP2104 is a COVID-19 mRNA vaccine that uses ST Pharm’s proprietary patented platform technology called 'SmartCap,' which enhances capping and transcription effects.

Analysis of a total of 120 specimens using the plaque reduction neutralization test (PRNT) showed that the neutralizing antibody titers formed four weeks after two primary doses administered at four-week intervals increased 22.8-fold compared to before vaccination.

Additionally, the seroconversion rate?defined as a fourfold or greater increase in neutralizing antibodies four weeks after the primary vaccination?was 100% (all 15 subjects) in the low-dose (25 μg) group and 93% (14 out of 15 subjects) in the high-dose (50 μg) group. The company explained that "the seroconversion rate of STP2104 is comparable to the 90?100% seroconversion rates of COVID-19 vaccines commercialized by global pharmaceutical companies."

An ST Pharm representative stated, "Through these interim results of STP2104, we have demonstrated the global competitiveness of ST Pharm’s proprietary patented platform SmartCap. We are confident this will open various business partnership opportunities, including mRNA contract development and manufacturing organization (CDMO) agreements utilizing our in-house lipid nanoparticle (LNP) technology, STLNP. We aim to become a global leader in gene therapy CDMO by pioneering the mRNA CDMO market beyond the global top three oligo CDMOs."

The interim Phase 1 clinical results of STP2104 are planned to be published in an SCI-level international journal. The final safety results of STP2104 are expected to be available in the first half of next year.

Meanwhile, ST Pharm had been preparing clinical trials for 'STP2250,' which can respond to various variants, but after confirming positive interim results with STP2104 and judging that the commercialization value of STP2250 was not significant, the company voluntarily withdrew the clinical trial for STP2250.