Candidate: AT-301

Type: Inhibitor of human host proteases found in the nasal mucosa, to prevent activation of the SARS-CoV-2 spike protein. Proprietary formula intended for nasal administration in patients immediately following diagnosis of COVID-19 but who have not yet exhibited symptoms severe enough to require hospitalization. Also intended for at-home use to proactively reduce symptoms of COVID-19, and to slow the infection rate so that a person’s immune system can more effectively fight SARS-CoV-2.

2021 Status: Atossa on February 25 announced final results from its Phase I trial (NCT04519788) showing AT-301 was considered to be safe and well tolerated in healthy male and female participants in this study at two different dose levels over 14 days.

Final analysis of data from the study indicated that there were no serious adverse events, no discontinuations, no bronchospasms. One participant of the 32 in the study experienced adverse events that were considered moderate in severity and all other adverse events were considered mild, Atossa said.

Steven Quay, MD, PhD, Atossa’s President and CEO, said in a statement that the company was preparing to conduct an additional preclinical study, “which we expect to start this quarter. Following that, we expect to apply to the FDA to commence a Phase II study here in the United States.”

2020 Status: Atossa said November 10 announced blinded preliminary results from its Phase I trial (NCT04519788) that it said showed AT-301 to be safe and well tolerated in this study at two different dose levels in both single and multiple dose forms over 14 days. “There we no serious adverse events, no discontinuations, and only one subject of the 32 subjects in the study experienced adverse events that were considered moderate in severity and all other adverse events were considered mild,” said Steven Quay, MD, PhD, Atossa’s President and CEO.

The double-blinded, randomized, and placebo-controlled Phase I safety study evaluated AT-301 nasal spray in 32 healthy adult subjects divided into two study groups: Part A, which consists of two single-dose cohorts receiving either active therapy, AT-301B, or the placebo comparator AT-301A; and Part B, a multiple dose arm with cohorts receiving either AT-301A or AT-301B for 14 days.

The primary aim of the trial, conducted in Australia, was to evaluate the safety and tolerability of single and multiple doses of AT-301 administered via nasal instillation to healthy volunteers. Secondary objectives included assessing the incidence and severity of local irritation and bronchospasm following administration of AT-301.

On October 19, Atossa said it planned to identify potential partners that are developing COVID-19 diagnostic tests with which AT-301 could be co-developed, with the goal of making the therapy available when a person tests positive for COVID-19.

Atossa also outlined other next steps for its development of AT-301, including contracting for a commercial supply of the nasal spray devices; and completing regulatory filings and approvals to launch a Phase II study, which is being planned for the first half of 2021.

The company said it plans to develop its nasal spray to help prevent COVID-19 infection—especially in high risk environments such as living with a patient infected with the virus, healthcare workers, emergency responders, or teachers.

On September 17, Atossa received a positive interim safety assessment from the second cohort of healthy participants in the Phase I trial of AT-301. The second group of eight participants received a single escalated dose of either AT-301A (placebo) or AT-301B (active drug).

On September 1, Atossa received its first positive safety assessment from the safety committee for the Phase I trial. The trial’s first cohort of eight healthy participants received a single dose of either AT-301A (placebo) or AT-301B (active drug).

In July, Atossa contracted with the Australian clinical research organizationAvance Clinical Pty Ltd to conduct the clinical study. Also that month, Atossa announced successful in vitro testing results for AT-301, saying that it inhibited SARS-CoV-2 infectivity of VERO cells in a laboratory culture. The testing was designed to mimic the virus’s entry process in vitro by examining the infectivity of VERO monkey kidney cells by authentic SARS-CoV-2 virus particles. Serial dilutions of the AT-301 formulation were performed from 1 to 4 to 1 to 4096.

Results showed that serial dilutions of the AT-301 nasal formulation—beginning with a 1 to 4 dilution and going to a 1 to 16 dilution—prevented N protein expression. Beginning at a 1 to 32 dilution, the virus was able to infect the cells, Atossa said, adding that minimal toxicity was seen.

“We may eventually develop AT-301 as a prophylaxis to reduce risk of being infected with COVID-19,” Quay said. “For example, it could be taken as a daily vaccine-like treatment for people at higher-risk, such as TSA workers, emergency medical professionals and hospital personnel.”

In May, Atossa said it had begun developing AT-301, the company’s second COVID-19 treatment program, for patients capable of being treated at home. The company envisioned offering treatments at both ends of the COVID-19 spectrum, with patients requiring mechanical ventilation in a hospital to be offered AT-H201.

Atossa said it retained Summit Biosciences, which specializes in nasal spray medicines, to develop and produce a clinical supply of pre-filled nasal spray products in multi-dose devices containing AT-301. Next steps, according to Atossa, will include designing and manufacturing clinical trial materials and the active pharmaceutical ingredients in AT-301, followed by studies intended to show safety and efficacy.

The company said it filed provisional patent applications on AT-301 to treat patients diagnosed with COVID-19, or prevent the disease via nasal spray, and added that it intended to apply to the FDA “as soon as possible” for authorization to conduct U.S. human clinical trials.

COVID-19: 200 Candidates and Counting

To navigate through the >200 potential therapeutic and vaccine options for COVID-19, GEN has grouped the candidates into four broad categories based on their developmental and (where applicable) clinical progress:

FRONT RUNNER – the most promising therapeutics/vaccines based on clinical progress, favorable data or both.

DEFINITELY MAYBE – earlier phases with promising partners, or more advanced candidates in development that have generated uneven data

KEEPING AN EYE ON… – interesting technology, attracting notable partners, or both, but preliminary data.

TOO SOON TO TELL – longshots pending additional experimental and/or clinical data.

GEN has also tagged the most common treatment types:


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