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The cell line NK-92, currently used in several clinical trials, has shown great potential in cancer immunotherapy due to strong cytotoxic capabilities and suitability as an off-the-shelf therapy. However, effective clinical application of NK-92 therapies requires optimised cell culture conditions, including cultivation medium composition and expansion methods. This study aimed at identifying optimal cultivation medium formulations and intensifying NK-92 cell expansion by systematically evaluating critical quality attributes and key performance indicators.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>We screened various cultivation media formulations, including alpha minimum essential medium, Roswell Park Memorial Institute medium, and stem cell growth medium, supplemented with either human serum, fetal bovine serum, chemically defined serum replacement, and a combination of fetal bovine serum and horse serum. Cells cultivated in alpha minimum essential medium supplemented with human serum significantly outperformed the other formulations, achieving the highest growth rate, maximum viable cell count, and superior cytotoxicity at high cost-efficiency. Media containing chemically defined serum replacement showed reduced cell proliferation despite high cytotoxicity per cell, indicating a complex balance between cell quantity and functionality. Following cultivation medium selection, cultivation strategies including batch, fed-batch, and repetitive batch were compared. The repetitive batch method, where cultivation medium is replenished repeatedly throughout the cultivation, demonstrated superior expansion capability, long-term cell viability, significantly improved cytotoxicity, although associated with higher medium consumption and thus costs.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>This study identified alpha minimum essential medium supplemented with human serum in repetitive batch cultivation as the optimal approach for NK-92 cell expansion. This combination enhances cell growth, viability, and cytotoxicity, meeting essential clinical quality attributes while maintaining cost-effectiveness. These findings provide valuable guidance and should act as a baseline for consistent, scalable, and commercially viable production of NK cell-based cancer therapies.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1186\/s12896-026-01116-2","type":"journal-article","created":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T03:48:03Z","timestamp":1771559283000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Cultivation strategy optimisation for NK-92 cell line expansion in static conditions"],"prefix":"10.1186","volume":"26","author":[{"given":"Valentin","family":"von Werz","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aleksander","family":"Szarzynski","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gregor","family":"Mattert","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sara","family":"Zigon-Branc","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Werner","family":"Dammermann","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Oliver","family":"Spadiut","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,2,20]]},"reference":[{"issue":"1\u20132","key":"1116_CR1","doi-asserted-by":"publisher","first-page":"107","DOI":"10.1615\/CritRevOncog.2014010866","volume":"19","author":"R Mishra","year":"2014","unstructured":"Mishra R, Welsh R, Szomolanyi-Tsuda E. 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