Arcturus Therapeutics (ARCT) Shares Fall Over 50% After Underwhelming Vaccine Data

Shares of biopharmaceutical firm Arcturus Therapeutics (NASDAQ: ARCT) are falling on Tuesday following underwhelming data from its Covid-19 vaccine candidate, ARCT-021.

Arcturus shares are down 52.90% at $43.53 at the time of writing, following Monday’s close at $92.35.

The company said that of the 106 participants in the Phase 1/2 trial, 78 received the vaccine while 28 received the placebo. 44 subjects received ARCT-021 at doses selected for Phase 2 (27 young adults and 17 older adults) while 34 participants received a single administration of 5 µg, 10 received a single administration of 7.5 µg, and 24 received a prime-boost regimen (5 µg x 2).

There were no safety concerns identified, while All adverse events except two were mild or moderate at doses selected for Phase 2.

The only serious adverse event was in a placebo participant.

All 44 subjects who received the 5µg or 7.5 µg dose had humoral immune responses for binding and/or neutralizing antibodies.

The company said that ARCT-021, both single administration and prime-boost regimens, were significantly effective in animal testing.

“We are pleased to advance ARCT-021 into a Phase 2 study based upon our promising Phase 1/2 data, which continues to support the potential for Arcturus’ STARR™ self-replicating mRNA technology to provide a highly effective, and differentiated clinical profile, including a single-dose regimen,” said Steve Hughes, Chief Development Officer of Arcturus.