Senior Scientist, Drug Substance

Position Summary The Senior Scientist, Drug Substance will drive the development and optimization of scalable, efficient, and sustainable synthetic routes for MBX’s peptide drug substances and intermediates. In this role, you’ll support late‑stage development activities, contribute to QbD initiatives, and help define control strategies aligned with global regulatory expectations. You will provide technical leadership and oversight for external CDMOs, supporting manufacturing campaigns, tech transfers, troubleshooting, and investigations. Collaboration across Discovery, Analytical Chemistry, Quality, Regulatory CMC, and Clinical teams is essential, as is the ability to work effectively with external consultants and manufacturing partners. Key Responsibilities Design, develop, and optimize robust, cost-effective synthetic routes to drug substance, drug substance intermediates and starting materials, with a focus on step reduction, convergence, scalability, efficiency and sustainability. Contribute to the development and execution of control strategies in alignment with global regulatory expectations. Support the qualification, technical oversight, and ongoing management of CDMOs manufacturing and releasing MBX’s peptide drug substance projects. Lead and support manufacturing campaigns for products at external CDMOs. Participate in technical transfers, process troubleshooting, and manufacturing investigations at partner sites. Contribute to Quality-by-Design (QbD) activities for late‑stage development, including risk assessments, identification of critical quality attributes (CQAs), and establishment of control strategies. Support process engineering, scale‑up, and process safety studies in collaboration with internal and external experts. Assist with analytical method development, qualification, and validation strategies as they relate to stage‑appropriate drug substance development and manufacturing. Author and/or technically review in‑process and release specifications, analytical methods, stability protocols, and master batch records. Contributes to the preparation and technical review of CMC sections of regulatory submissions for US and ex‑US filings. Ensure activities are aligned with relevant regulatory guidance (e.g., ICH Q7, ICH Q11). Work closely with internal stakeholders, including Discovery, Analytical Chemistry, Quality, Regulatory CMC, and Clinical teams. Collaborate effectively with external consultants and manufacturing partners to ensure alignment of technical and program objectives. Other responsibilities as assigned. Education & Qualifications Bachelors in Chemistry, Biochemistry, Pharmaceutical Sciences, or related discipline with 7+ years of relevant industry experience; or M.S. or PhD with 5+ years of CMC drug substance experience in the biopharmaceutical industry. Strong expertise in peptide drug substance development and manufacturing for clinical scale supply, process characterization and optimization, technical transfers, and process validation. Experience with an asset that was successfully commercialized is a plus. Solid knowledge of cGMPs, Quality systems, and global regulatory requirements. Experience with drafting of regulatory submissions (IND, NDA, MAA, etc.). Familiarity with regulatory requirements and guidelines (ICH, FDA, EMA, JP) related to CMC development. Proven ability to interpret complex analytical data and apply scientific judgment to development and troubleshooting. Experience managing activities at external partners (CROs/CMOs) and driving cross‑functional collaborations. Excellent written and verbal communication skills, including experience authoring regulatory documentation. Strong organizational skills with the ability to manage multiple priorities in a fast‑paced environment. Travel & Location You will be expected to travel periodically, based on business needs, including attending Together Weeks, Together Days, and functional meetings as requested by the Company. This role is expected to be on‑site an average of three days per week, unless otherwise requested. Company Overview MBX Biosciences is a biopharmaceutical company focused on the discovery, development and commercialization of novel precision peptide therapies based on its proprietary PEP™ platform, for the treatment of endocrine and metabolic disorders. The Company is advancing a pipeline of novel candidates for endocrine and metabolic disorders with clinically validated targets, established endpoints for regulatory approval, significant unmet medical needs and large potential market opportunities. The Company’s pipeline includes canvuparatide (MBX 2109) for the treatment of chronic hypoparathyroidism preparing for Phase 3 development; and an obesity portfolio that includes MBX 4291 in Phase 1 development and MBX 5765 in preclinical development, as well as additional discovery candidates. The Company is based in Carmel, Indiana and Burlington, Massachusetts. To learn more, please visit the Company website at and follow it on LinkedIn. EEO Statement MBX Biosciences is an Equal Opportunity Employer and is committed to treating all applicants fairly without discrimination. We welcome applications from all individuals, regardless of race, national origin, gender, age, physical characteristics, social origin, disability, union membership, religion, family status, pregnancy, sexual orientation, gender identity, gender expression or any unlawful criterion under applicable law. #J-18808-Ljbffr MBX Biosciences, Inc.