{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T14:07:27Z","timestamp":1789135647309,"version":"build-2803163510"},"reference-count":26,"publisher":"American Chemical Society (ACS)","issue":"9","license":[{"start":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T00:00:00Z","timestamp":1781740800000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-029"},{"start":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T00:00:00Z","timestamp":1781740800000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-037"},{"start":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T00:00:00Z","timestamp":1781740800000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-045"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,9,11]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>The classical complement pathway is a critical therapeutic target for numerous diseases, but the lack of robust, translatable biomarkers hinders drug development. Here, we report the development and qualification of a quantitative liquid chromatography-tandem mass spectrometry (LC\u2013MS\/MS) platform to measure key classical pathway proteins\u2500C1q, C 1s (total and active), and the native C1q\/C 1s complex. The platform was established across human, cynomolgus monkey, and mouse samples, including serum, plasma, cerebrospinal fluid, and brain homogenates. We employed two complementary workflows: an affinity capture LC\u2013MS\/MS method to quantify the intact C1q\/C 1s complex and a direct digestion strategy to differentiate total C 1s from its active form. The assays met rigorous qualification standards for accuracy, reproducibility (CV \u226415%) and freeze\u2013thaw stability. Applying this platform, we established that cynomolgus monkeys exhibit complement profiles highly similar to those in healthy humans, validating their use as a translational model. In contrast, mice display markedly higher baseline levels of active C 1s, revealing a critical species-specific difference in complement regulation. This qualified, cross-species platform provides an essential tool for bridging preclinical and clinical research and enabling reliable pharmacodynamic assessment of complement-targeting therapeutics.<\/jats:p>","DOI":"10.1021\/acsptsci.5c00784","type":"journal-article","created":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T05:44:13Z","timestamp":1781761453000},"page":"2426-2437","source":"Crossref","is-referenced-by-count":0,"title":["Direct Quantification\nof Complement Biomarkers Using\nLiquid Chromatography\u2013Tandem Mass Spectrometry (LC\u2013MS\/MS)"],"prefix":"10.1021","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4314-4197","authenticated-orcid":true,"given":"Cong","family":"Wu","sequence":"first","affiliation":[{"name":"Genentech, Inc. , , ,","place":["South San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jianhui","family":"Zhu","sequence":"additional","affiliation":[{"name":"NovaBioAssays LLC , , ,","place":["Woburn, Massachusetts, United States, 01801"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tiffany","family":"Wong","sequence":"additional","affiliation":[{"name":"Genentech, Inc. , , ,","place":["South San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Racquel","family":"Corpuz","sequence":"additional","affiliation":[{"name":"Genentech, Inc. , , ,","place":["South San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9273-0574","authenticated-orcid":true,"given":"Tiffany","family":"Wu","sequence":"additional","affiliation":[{"name":"Genentech, Inc. , , ,","place":["South San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"William J.","family":"Meilandt","sequence":"additional","affiliation":[{"name":"Genentech, Inc. , , ,","place":["South San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anne","family":"Biever","sequence":"additional","affiliation":[{"name":"Genentech, Inc. , , ,","place":["South San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Norbert","family":"LeClair","sequence":"additional","affiliation":[{"name":"Genentech, Inc. , , ,","place":["South San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3733-099X","authenticated-orcid":true,"given":"Kelly","family":"Loyet","sequence":"additional","affiliation":[{"name":"Genentech, Inc. , , ,","place":["South San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jesse","family":"Hanson","sequence":"additional","affiliation":[{"name":"Genentech, Inc. , , ,","place":["South San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John","family":"Chen","sequence":"additional","affiliation":[{"name":"NovaBioAssays LLC , , ,","place":["Woburn, Massachusetts, United States, 01801"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chengjie","family":"Ji","sequence":"additional","affiliation":[{"name":"NovaBioAssays LLC , , ,","place":["Woburn, Massachusetts, United States, 01801"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John C.","family":"Tran","sequence":"additional","affiliation":[{"name":"Genentech, Inc. , , ,","place":["South San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6157-0937","authenticated-orcid":true,"given":"Luis F.","family":"Schachner","sequence":"additional","affiliation":[{"name":"Genentech, Inc. , , ,","place":["South San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,6,18]]},"reference":[{"key":"2026091109132903900_cit1","doi-asserted-by":"publisher","first-page":"785","DOI":"10.1038\/ni.1923","article-title":"Complement: A Key\nSystem for Immune Surveillance and Homeostasis","volume":"11","author":"Ricklin","year":"2010","journal-title":"Nat. Immunol."},{"key":"2026091109132903900_cit2","doi-asserted-by":"publisher","first-page":"479","DOI":"10.1016\/j.semnephrol.2013.08.001","article-title":"Overview of Complement\nActivation and Regulation","volume":"33","author":"Noris","year":"2013","journal-title":"Semin. Nephrol."},{"key":"2026091109132903900_cit3","doi-asserted-by":"publisher","first-page":"36","DOI":"10.3389\/fimmu.2016.00036","article-title":"Early Components\nof the Complement Classical Activation Pathway in Human Systemic Autoimmune\nDiseases","volume":"7","author":"Lintner","year":"2016","journal-title":"Front. Immunol."},{"key":"2026091109132903900_cit4","doi-asserted-by":"publisher","first-page":"354","DOI":"10.1186\/s12974-020-02024-8","article-title":"The Good, the Bad,\nand the Opportunities of the Complement\nSystem in Neurodegenerative Disease","volume":"17","author":"Schartz","year":"2020","journal-title":"J. Neuroinflammation"},{"key":"2026091109132903900_cit5","doi-asserted-by":"publisher","first-page":"10016","DOI":"10.1073\/pnas.89.21.10016","article-title":"Complement Activation by Beta-Amyloid\nin Alzheimer Disease","volume":"89","author":"Rogers","year":"1992","journal-title":"Proc. Natl. Acad. Sci.\nU.S.A."},{"key":"2026091109132903900_cit6","doi-asserted-by":"publisher","first-page":"817","DOI":"10.3390\/ijms25020817","article-title":"The Importance of\nComplement-Mediated Immune Signaling in Alzheimer\u2019s Disease\nPathogenesis","volume":"25","author":"Batista","year":"2024","journal-title":"Int. J. Mol. Sci."},{"key":"2026091109132903900_cit7","doi-asserted-by":"publisher","first-page":"1015128","DOI":"10.3389\/fimmu.2022.1015128","article-title":"Complement C1s as a\nDiagnostic Marker and Therapeutic Target: Progress and Prospective","volume":"13","author":"Ye","year":"2022","journal-title":"Front. Immunol."},{"key":"2026091109132903900_cit8","doi-asserted-by":"publisher","first-page":"2048","DOI":"10.4049\/jimmunol.165.4.2048","article-title":"The Cleavage of Two C1s Subunits\nby a Single Active C1r Reveals Substantial Flexibility of the C1s-C1r-C1r-C1s\nTetramer in the C1 Complex","volume":"165","author":"Lo\u0308rincz","year":"2000","journal-title":"J. Immunol."},{"key":"2026091109132903900_cit9","doi-asserted-by":"publisher","first-page":"444","DOI":"10.3389\/fimmu.2014.00444","article-title":"The Role\nof the Lys628 (192) Residue\nof the Complement Protease, C1s, in Interacting with Peptide and Protein\nSubstrates","volume":"5","author":"Wijeyewickrema","year":"2014","journal-title":"Front. Immunol."},{"key":"2026091109132903900_cit10","doi-asserted-by":"publisher","first-page":"976","DOI":"10.1016\/j.addr.2011.05.010","article-title":"Advances in Assay of Complement Function\nand Activation","volume":"63","author":"Harboe","year":"2011","journal-title":"Adv. Drug Delivery Rev."},{"key":"2026091109132903900_cit11","doi-asserted-by":"publisher","first-page":"87","DOI":"10.1016\/j.jim.2014.01.011","article-title":"A Specific Assay for Quantification of Human C4c by\nUse of an Anti-C4c Monoclonal Antibody","volume":"405","author":"Pilely","year":"2014","journal-title":"J. Immunol.\nMethods"},{"key":"2026091109132903900_cit12","doi-asserted-by":"publisher","first-page":"1178","DOI":"10.1002\/art.1780390716","article-title":"Sensitivity\nand Specificity of Plasma and Urine Complement Split Products as Indicators\nof Lupus Disease Activity","volume":"39","author":"Manzi","year":"1996","journal-title":"Arthritis Rheum."},{"key":"2026091109132903900_cit13","doi-asserted-by":"publisher","first-page":"7","DOI":"10.4155\/bio-2021-0186","article-title":"Challenges with Development of a\nPharmacokinetics Assay\nto Measure a Variably Glycosylated Fusion Protein","volume":"14","author":"Sperinde","year":"2022","journal-title":"Bioanalysis"},{"key":"2026091109132903900_cit14","doi-asserted-by":"publisher","first-page":"7940","DOI":"10.1002\/alz.14271","article-title":"CSF Complement Proteins Are Elevated\nin Prodromal to Moderate Alzheimer\u2019s Disease Patients and Are\nNot Altered by the Anti-tau Antibody Semorinemab","volume":"20","author":"Sandoval","year":"2024","journal-title":"Alzheimer\u2019s Dement"},{"key":"2026091109132903900_cit15","doi-asserted-by":"publisher","first-page":"49","DOI":"10.1016\/j.ddtec.2021.06.006","article-title":"Data-Independent\nAcquisition (DIA):\nAn Emerging Proteomics Technology for Analysis of Drug-Metabolizing\nEnzymes and Transporters","volume":"39","author":"Li","year":"2021","journal-title":"Drug Discovery Today:\nTechnol."},{"key":"2026091109132903900_cit16","doi-asserted-by":"publisher","first-page":"206","DOI":"10.1038\/nchembio.2576","article-title":"How Many Human\nProteoforms Are There?","volume":"14","author":"Aebersold","year":"2018","journal-title":"Nat. Chem. Biol."},{"key":"2026091109132903900_cit17","doi-asserted-by":"publisher","first-page":"9880","DOI":"10.3390\/ijms25189880","article-title":"Mass Spectrometry Advancements and Applications for\nBiomarker Discovery,\nDiagnostic Innovations, and Personalized","volume":"25","author":"Son","year":"2024","journal-title":"Medicine.\nInt. J. Mol. Sci."},{"key":"2026091109132903900_cit18","doi-asserted-by":"publisher","first-page":"742","DOI":"10.1126\/science.aay8086","article-title":"Translating\nPreclinical Models to Humans","volume":"367","author":"Brubaker","year":"2020","journal-title":"Science"},{"key":"2026091109132903900_cit19","doi-asserted-by":"publisher","DOI":"10.1128\/mbio.00282-24","article-title":"Sex- and Species-Associated\nDifferences\nin Complement-Mediated Immunity in Humans and Rhesus Macaques","volume":"15","author":"Kelkar","year":"2024","journal-title":"mBio"},{"key":"2026091109132903900_cit20","doi-asserted-by":"publisher","first-page":"151","DOI":"10.1084\/jem.181.1.151","article-title":"Mouse Complement Regulatory Protein\nCrry\/P65 Uses the Specific Mechanisms of Both Human Decay-Accelerating\nFactor and Membrane Cofactor Protein","volume":"181","author":"Kim","year":"1995","journal-title":"J. Exp.\nMed."},{"key":"2026091109132903900_cit21","doi-asserted-by":"publisher","first-page":"2953","DOI":"10.4049\/jimmunol.181.5.2953","article-title":"Comparative Functional\nEvolution of Human and Mouse\nCR1 and CR2","volume":"181","author":"Jacobson","year":"2008","journal-title":"J. Immunol."},{"key":"2026091109132903900_cit22","doi-asserted-by":"publisher","first-page":"147","DOI":"10.1016\/0022-1759(89)90088-4","article-title":"Mouse Strains with Typical Mammalian\nLevels of Complement\nActivity","volume":"125","author":"Ong","year":"1989","journal-title":"J. Immunol. Methods"},{"key":"2026091109132903900_cit23","doi-asserted-by":"publisher","first-page":"2731","DOI":"10.4049\/jimmunol.172.5.2731","article-title":"Of Mice and Not\nMen: Differences between Mouse and\nHuman Immunology","volume":"172","author":"Mestas","year":"2004","journal-title":"J. Immunol."},{"key":"2026091109132903900_cit24","doi-asserted-by":"publisher","first-page":"195","DOI":"10.1016\/j.jim.2009.11.003","article-title":"Preparing\nSerum for Functional Complement Assays","volume":"352","author":"Lachmann","year":"2010","journal-title":"J. Immunol.\nMethods"},{"key":"2026091109132903900_cit25","doi-asserted-by":"publisher","first-page":"8989","DOI":"10.1523\/JNEUROSCI.23-26-08989.2003","article-title":"PS2APP Transgenic\nMice, Coexpressing\nHPS2mut and HAPPswe, Show Age-Related Cognitive Deficits Associated\nwith Discrete Brain Amyloid Deposition and Inflammation","volume":"23","author":"Richards","year":"2003","journal-title":"J. Neurosci."},{"key":"2026091109132903900_cit26","doi-asserted-by":"publisher","first-page":"2024","DOI":"10.1101\/2024.08.23.609240","article-title":"Therapeutically\nTargeting the Classical Complement Pathway with Antisense Oligonucleotides\nin Alzheimer\u2019s Disease","volume":"23","author":"Wang","year":"2024","journal-title":"bioRxiv Epub\nAug"}],"container-title":["ACS Pharmacology &amp; Translational\nScience"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/acsptsci.5c00784","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/aptsfn\/article-pdf\/9\/9\/2426\/65126004\/acsptsci.5c00784.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/aptsfn\/article-pdf\/9\/9\/2426\/65126004\/acsptsci.5c00784.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T13:18:58Z","timestamp":1789132738000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/aptsfn\/article\/9\/9\/2426\/5160187\/Direct-Quantification-of-Complement-Biomarkers"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,18]]},"references-count":26,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2026,6,18]]},"published-print":{"date-parts":[[2026,9,11]]}},"URL":"https:\/\/doi.org\/10.1021\/acsptsci.5c00784","relation":{},"ISSN":["2575-9108"],"issn-type":[{"value":"2575-9108","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,18]]}}}