Risk Factors Update Summary

• Identified substantial doubt regarding ability to continue as a going concern due to accumulated deficit of $144.5 million in 2023, up from $101.6 million in 2022.
• Addition of new products, including Infectimune®, to patent protection increases IP risks.
• Sales of common stock increased significantly from 238,642 shares in 2022 to 3,428,681 shares in the first quarter of 2024.
• Increase in common stock outstanding from 317M to 521M shares.
• Research and development expenses expected to increase significantly for Versamune-based products.
• Ongoing monitoring of geopolitical tensions, including the situation in Ukraine, and potential impacts.
• Clinical trials are expensive; enrollment and retention challenges may impact the development of PDS0101 and PDS01ADC.
• Executive orders regarding China may impact pharmaceutical industry and current manufacturing partners.
• Failure to comply with federal and state healthcare regulatory laws could lead to criminal prosecution and sanctions.
• Dependence on third-party manufacturers and CROs for clinical trials execution and commercialization may pose risks.
• Uncertainty in securing additional funding and accumulated deficit raise doubts about the ability to continue as a going concern.