QUEBEC CITY—Medicago announced interim Phase 1 results from the clinical trial of its plant-derived vaccine for COVID-19, in which 100 percent of subjects demonstrated an encouraging antibody response after two doses of the vaccine candidate. No severe adverse events were reported, and reactogenicity events—expected reactions to vaccination that indicate an immune response, such as soreness at the injection site—were typically mild to moderate and short in duration.
The Phase 1 clinical trial was a randomized, partially blinded study of 180 healthy subjects, male and female aged 18-55, and evaluated dosages of 3.75, 7.5 or 15 micrograms of the recombinant Coronavirus Virus-Like Particle (CoVLP) vaccine candidate alone or with an adjuvant in a prime-boost regimen. Medicago tested its vaccine candidate with each of two adjuvants—GlaxoSmithKline's proprietary pandemic adjuvant technology and Dynavax’s CpG 1018—both of which generated significant humoral and cell-mediated immune responses. GSK's pandemic adjuvant was dose-sparing, with the 3.75 µg dose of CoVLP performing comparably with the 7.5 or the 15 µg doses, and all subjects in this adjuvant group developed anti-spike IgG antibodies after a single dose at any dose level.
The data from the interim analysis have been published on an online preprint server at medRxiv.org.
“The positive results of our Phase 1 clinical trial are a step forward in the fight against the COVID-19 pandemic, and we are confidently moving forward to our Phase 2/3 trial. We’re pleased that Medicago’s innovative manufacturing technology is helping to diversify the classes of COVID-19 vaccines candidates in development. In addition to supplying up to 76 million doses to the government of Canada, we are ready to participate globally in the fight against COVID-19,” said Dr. Bruce D. Clark, president and CEO of Medicago. “We would like to express our gratitude to the clinical trial participants who have generously dedicated their time to support the advancement of Medicago’s COVID-19 vaccine candidate. We also would like to extend our thanks to our partners GSK and Dynavax, as well as the clinical investigators.”
“These are very promising results. After two doses, the adjuvanted vaccine candidate induced robust neutralizing antibody and cellular immune responses which is encouraging and support further clinical evaluation,” added Nathalie Landry, executive vice president of Scientific and Medical Affairs at Medicago. “We also observed that the antibody levels were higher after vaccination than those observed in convalescent sera from people who recovered from the disease.”
Medicago quickly followed the news of the Phase 1 results with the announcement that it had begun Phase 2/3 trials for the vaccine candidate to assess its efficacy, safety and immunogenicity. Given the Phase 1 data, the trial will proceed with GlaxoSmithKline's pandemic adjuvant. The multi-portion study will confirm the immunogenicity and safety of the vaccine formulation and dosing regimen: two doses of 3.75 µg CoVLP combined with GSK's pandemic adjuvant given 21 days apart.
The Phase 2 trial portion of the study will be a randomized, observer-blind, placebo-controlled study to evaluate the safety and immunogenicity of the adjuvanted recombinant COVID-19 plant-derived vaccine candidate in subjects aged 18 and above. It will be conducted in multiples sites in Canada and, upon FDA allowance, in the United States and on a population composed of healthy adults (18-64 years) and elderly adults (over 65 years). Each age group will have more than 300 subjects randomized 5:1 to receive the adjuvanted CoVLP vaccine candidate vs. placebo, and with 2:1 stratification in older adults (65-74 and ≥75). All subjects will be followed for 12 months after the last vaccination to ascertain safety and durability of the immune responses.
The Phase 3 part of the study, which is expected to begin before the end of the year, is an event-driven, randomized, observer-blinded, placebo-controlled design to evaluate the efficacy and safety of the CoVLP formulation, compared to placebo. The trial will consist of more than 30,000 subjects in North America, Latin America and/or Europe and within the same population as the Phase 2 trial, or amongst a broader one should regulatory authorities approve it.
“This is the first of several GSK COVID-19 vaccine candidate collaborations to start Phase 2/3 clinical testing and an important step forward in our contribution to the global fight against the pandemic,” Thomas Breuer, chief medical officer for GSK Vaccines, remarked. “We are delighted with the very promising Phase 1 results of Medicago's COVID-19 vaccine candidate in combination with GSK's pandemic adjuvant. Proven dose-sparing and a high immune response due to GSK's adjuvant make us confident of delivering an efficacious vaccine with an acceptable safety profile in collaboration with Medicago.”