Senior Scientist, LC-MS​/MS

Yowei Therapeutics and Yowei Oncology are stealth-stage life-sciences companies working closely with CSBio to advance peptide-based clinical programs. Their work spans longevity and peptide therapeutics, clinical trials, evaluation of a 503A pharmacy model, personalized synthetic neoantigen peptide oncology programs, and supporting microbiology and laboratory capabilities. Together, they are building the clinical, pharmacy, data, laboratory, and operational infrastructure needed to responsibly translate peptide programs into patient-facing studies and services.

Both companies expect to remain in stealth through Q1 2027.

CSBio is a peptide contract manufacturing founded in 1993. CSBio initial products were a complete line of automated synthesizers for manufacturing and process development, with a focus on cGMP production. In 1994, CSBio opened a custom peptide facility and began producing high quality compounds for research organizations and pharmaceutical companies worldwide. In 2004, CSBio opened a peptide production facility in Menlo Park, CA and in 2014, CSBio expanded production capability through the addition of a new, state of the art building dedicated to cGMP peptide production.

In 2017, CSBio passed a FDA inspection and were recommended to be approved for commercial drug substance manufacturing. In 2023, additional cGMP clinical production capacity was added in Milpitas, CA.

Yowei Therapeutics is seeking a Senior Scientist to own LC-MS/MS for regulated bioanalytical testing in support of pharmacokinetic (PK) studies for the company’s peptide clinical programs. This is a hands-on, single-owner role responsible for the full method lifecycle — development and validation. Core duties are included below.

Job Duties:

• Develop, qualify, and validate LC-MS/MS bioanalytical methods for quantitation of peptide therapeutics and, where required, their metabolites in biological matrices (plasma, serum, tissue) to support nonclinical and clinical PK studies.
• Execute full bioanalytical method validation to ICH M10 — selectivity, specificity, calibration curve and range, within- and between-run accuracy and precision, matrix effect and recovery, carryover, dilution integrity, and the complete stability panel (stock/working solution, benchtop, freeze-thaw, processed/autosampler, and long-term matrix stability).
• Design and manage study sample analysis runs, including run acceptance criteria, calibration and QC schemes, reassay rules, and incurred sample reanalysis (ISR).
• Establish fit-for-purpose peptide sample preparation — protein precipitation, solid-phase extraction, and hybrid immunocapture-LC-MS/MS where sensitivity demands — using stable-isotope-labeled internal standards and surrogate-peptide (signature peptide) strategies as appropriate.
• Address peptide-specific bioanalytical challenges, including non-specific/adsorptive loss, protease-driven instability, and quantitation of endogenous or endogenous-like peptides (e.g., thymosin β4-class analytes) requiring surrogate-matrix or authentic-matrix background-subtraction approaches.
• Author bioanalytical validation protocols, validation reports, study analytical plans, and the corresponding sections of regulatory submissions.

• Ph.D. in analytical chemistry, biochemistry, or a related field with 4–7 years of hands-on LC-MS/MS experience; or M.S./B.S. with 8–12 years of experience in GLP laboratory environments and GMP environments.
• Demonstrated, hands-on expertise in developing and validating LC-MS/MS bioanalytical methods for quantitation of peptides or other biologics in biological matrices (e.g., plasma, serum) to support PK studies.
• Direct, hands-on experience with regulated bioanalytical method validation and study sample analysis under ICH M10…