SNK01 autologous NK cell therapy demonstrated a positive effect on cerebral spinal fluid (“CSF”) and plasma Tau proteins in Alzheimer’s patients. The additional Phase 1 SNK01 trial data suggest clinical activity regarding cognitive function in patients with advanced Alzheimer’s disease in addition to previously disclosed positive effects on amyloid protein and neuroinflammation biomarkers. SANTA ANA, Calif., March 25, 2024 (GLOBE NEWSWIRE) — NKGen Biotech, Inc. (Nasdaq: NKGN) (“NKGen” or the “Company”), a clinical-stage biotechnology company focused on the development and commercialization of innovative autologous, allogeneic, and CAR-NK Natural Killer (“NK”) cell therapeutics, today presented additional Phase 1 clinical trial data on the use of its investigational autologous NK cell therapy, SNK01, to treat patients with Alzheimer’s disease (“AD”) at the Tau2024 Global Conference in Washington, D.C. The presentation contained data from an abstract entitled, “Beneficial Effect on CSF and Plasma Tau Proteins and Cognitive Function in Alzheimer’s Disease Subjects Treated with Expanded Non-Genetically Modified Autologous Natural Killer Cells (SNK01).” In this Phase 1 study, SNK01 was administered intravenously (“IV”) every three weeks for a total of four treatments using a 3+3 dose escalation design (1, 2, and 4 x 109 cells) in patients with either mild, moderate, or severe AD (Median MMSE of 14). Cognitive assessments and CSF/plasma pTau217 and pTau181 analyses were performed at baseline and at 1 and 12 weeks after the final dose. The primary endpoint was safety and secondary endpoints included changes in cognitive assessments and biomarker levels. “The data presented today demonstrate additional beneficial effects of SNK01 for the treatment of Alzheimer’s disease,” commented Paul Y. Song, M.D., CEO of NKGen. “The data from this Phase 1 trial further validates the ability of SNK01 to improve pTau, amyloid Aβ42/40, and alpha-synuclein biomarkers as well as improving cognitive scores, consistent with what we have previously observed. While the results were positive, the Phase 1 trial was a dose-escalation trial that only administered four total doses over 11 weeks. However, our Phase 1/2a SNK01 trial in moderate Alzheimer’s patients, initiated in December 2023, utilizes a 50% higher dose than the highest dose administered in the prior Phase 1, and prolonged dosing regimen for over one year in which we expect to show an even greater clinical benefit. We are excited to continue our research with the goal of offering our NK cell therapy to patients with Alzheimer’s disease who are in need of disease modifying treatments.” Highlights from the Presentation: Of the 11 patients enrolled, 10 were evaluable – median MMSE was 14.SNK01 given via a simple IV appears to cross the blood brain barrier to improve Aβ42/40, Tau, and alpha-synuclein protein levels in CSF.Despite 70% of patients treated at relatively low doses of SNK01, at one-week post-treatment (week 11): 50–70% of all enrolled patients in the trial had either stable or improved CDR-SB, ADAS-Cog and/or MMSE scores including one patient whose MMSE score improved from 14 to 23.90% had either stable or improved ADCOMS scores.50% of patients had a decrease in CSF pTau217.80% had stable/decreased CSF pTau181 compared to baseline values.30% had a decrease in plasma pTau217. 40% had a decrease in plasma pTau181. Where data were available, this decrease continued through week 22 (12 weeks after the last dose) for CSF pTau217 for all patients (n=4), for CSF pTau181 for 5/7 patients, for plasma pTau217 for 2/3 patients, and for plasma pTau181 for 3/4 patients. At week 11, the percent of patients with a stable/improved ADCOMS score who also had a decrease in CSF pTau was 56% for pTau217 and 78% for pTau181.No treatment related adverse events were observed.SNK01 appears safe and well tolerated and the data suggest SNK01 may have potential clinical activity in AD while also reducing CSF and plasma Tau protein levels. A larger trial with a higher dosing/duration was initiated in the U.S. in 2023. A copy of the abstract and presentation materials will be available on the Scientific Publications page of the Company’s website at https://nkgenbiotech.com/ once the presentation has concluded. Previously disclosed Phase 1 data on the positive effects of SNK01 on amyloid and neuroinflammation biomarkers, which are not included in this Tau-focused conference presentation, can also be found on the Scientific Publications page. About NKGen Biotech NKGen is a clinical-stage biotechnology company focused on the development and commercialization of innovative autologous, allogeneic, and CAR-NK Natural Killer cell therapeutics. NKGen is headquartered in Santa Ana, California, USA. For more information, please visit www.nkgenbiotech.com. Forward-Looking Statements Statements contained in this press release may contain “forward-looking statements” within the meaning of Section 27A of the Securities Act and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements may be identified by the use of words such as “anticipate”, “believe”, “could”, “continue”, “expect”, “estimate”, “may”, “plan”, “outlook”, “future” and “project” and other similar expressions that predict or indicate future events or trends or that are not statements of historical matters. Because such statements are subject to risks and uncertainties, many of which are outside of the Company’s control, actual results may differ materially from those expressed or implied by such forward-looking statements. Such statements include, but are not limited to, statements regarding the Company’s plans and expected timing for developing SNK01, including the expected timing of completing and announcing further results from its ongoing Phase 1 clinical study; and the Company’s expected timing for developing its product candidates and potential benefits of its product candidates. Risks that contribute to the uncertain nature of the forward-looking statements include: the Company’s ability to execute its plans and strategies; risks related to performing clinical studies; the risk that initial and interim results of a clinical study do not necessarily predict final results and that one or more of the clinical outcomes may materially change as patient enrollment continues, following more comprehensive reviews of the data, and as more patient data become available; potential delays in the commencement, enrollment and completion of clinical studies and the reporting of data therefrom; the risk that studies will not be completed as planned; the risk that the abstract will not be published as planned including delays in timing, format, or accessibility; and NKGen’s ability to raise additional funding to complete the development of its product candidates. These and other risks and uncertainties are described more fully under the caption “Risk Factors” and elsewhere in the Company’s filings and reports, which may be accessed for free by visiting the Securities and Exchange Commission’s website at www.sec.gov and on the Company’s website under the subheading “Investors—Financial and Filings”. Investors should take such risks into account and should not rely on forward-looking statements when making investment decisions. All forward-looking statements contained in this press release speak only as of the date on which they were made. The Company undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made, except as required by law. Internal Contact:Denise Chua, MBA, CLS, MT (ASCP)Vice President, Investor Relations and Corporate Communications949-396-6830dchua@nkgenbiotech.com External Contacts:Chris CalabreseManaging DirectorLifeSci Advisors, LLCccalabrese@lifesciadvisors.com Kevin GardnerManaging DirectorLifeSci Advisors, LLCkgardner@lifesciadvisors.com