Zentek Announces Successful Aptamer Testing for Longevity of Protection and Minimum Effective Dose

GUELPH, ON / ACCESSWIRE / October 10, 2023 / Zentek Ltd. ("Zentek" or the "Company") (Nasdaq:ZTEK)(TSX-V:ZEN), an intellectual property technology development and commercialization company is pleased to announce further successful pre-clinical testing of the aptamer-based platform technology by the Dr. Matthew Miller Lab.

After initial promising results released on July 27^th, 2023, which featured an aptamer therapeutic/prophylactic using the novel platform technology developed by the lab of Dr. Yingfu Li and tested by the team of Dr. Matthew Miller, further preclinical testing has been completed supporting this aptamer as a lead therapeutic target.

Longevity of Protection

An in vivo preclinical longevity of protection study was conducted to assess the safety and efficacy of the aptamer-based treatment over a period of 24 hours. This duration was chosen to mimic a suitable prophylactic use case that balances the convenience of a daily dose while maintaining complete protection. The study successfully demonstrated that the novel aptamer provided 24 hours of neutralizing protection against SARS-CoV-2 and improves the potential of the aptamer as a prophylactic in a setting that is both commercially and clinically relevant.

The trial used three test groups of 10 mice, which were administered three separate treatments 24 hours prior to administering the virus:

• Group 1 - control that was administered saline
• Group 2 - received the novel aptamer developed by the Li lab
• Group 3 - received the S309 antibody treatment; the most effective antibody against SARS-CoV-2 variants that received emergency use approval

After 24 hours, all mice received a lethal challenge (10^5 PFU) of the original Wuhan strain of SARS-CoV-2. Viral titers were measured and histopathology was performed at the end of the 7-day study. The mice that received the aptamers showed no clinical signs of infection, similar to those that received the S309 antibody.

Minimum Effective Dose

A subsequent study was conducted to determine the minimal effective dose of the aptamer required to protect against a lethal challenge (10^5 PFU) of SARS-CoV-2 - an important step in safety profile and resource efficiency optimization. Four separate groups of 10 mice were tested in the experiment:

• Group 1 - control that received saline
• Group 2 - received the original aptamer dosage (258µM)
• Group 3 - received a 10-fold lower dose (25.8 µM)
• Group 4 - received a 50-fold lower dose (5.16 µM)

After two hours, mice were challenged with a lethal dose of SARS-CoV-2 . The Group 2 mice that received 258 µM of aptamer were consistent with the previous tests reported on July 27^th, where the aptamers provided sterilizing protection. Group 3, which received a ten-fold lower dose (25.8 µM), showed no clinical markers of infection demonstrating that this lower aptamer dose still provided complete protection against SARS-CoV-2. Group 4 that received the lowest dose showed signs of infection similar to the control group suggesting that an optimum dosage is in the range of 25.8 µM through this delivery system.