Principal Scientist, Platform Development – Linker-Payload & Conjugation Technologies

About Xcellon

At Xcellon Biologics, we are building next-generation platforms for complex biologics, including antibody-drug conjugates (ADCs), multispecific biologics, targeted conjugates, and emerging precision delivery systems. Our mission is to accelerate the development and manufacturing of innovative therapeutics through integrated discovery, conjugation, analytics, and CMC capabilities.

We are seeking a highly driven and scientifically innovative Principal Scientist, Platform Development – Linker-Payload & Conjugation Technologies to help lead the advancement of our next-generation conjugation technologies and platform capabilities.

This role sits at the intersection of chemistry, biologics, translational science, manufacturing, and client-facing technical leadership and will play a critical role in shaping Xcellon’s internal technology platforms, strategic collaborations, and therapeutic pipeline initiatives.

Position Overview

The Principal Scientist will lead the development of novel linker-payload systems, conjugation technologies, and targeted delivery platforms for oncology and emerging therapeutic modalities. The ideal candidate will possess deep scientific expertise in conjugation chemistry and ADC development, combined with the ability to drive platform innovation and cross-functional programs from concept through preclinical development.

In addition to internal platform development, this role will serve as a key scientific subject matter expert (SME) supporting Xcellon’s ADC and bioconjugation CDMO clients. The individual will interface directly with partners and customers to provide technical guidance across conjugation strategy, linker-payload selection, developability, manufacturing readiness, and early CMC considerations.

This individual will work closely with chemistry, biologics, analytical, process development, and CMC teams to build differentiated platform technologies and advance both internal and partner programs.

The role is ideal for a scientist who thrives in an entrepreneurial, fast-paced, innovation-driven environment and is excited by the opportunity to help build foundational technologies in the rapidly evolving conjugated therapeutics space.

Key Responsibilities

Scientific & Technical Leadership

• Lead the design, development, and optimization of next-generation linker-payload systems for ADCs and related targeted therapeutics.
• Drive innovation in conjugation technologies, including:
• Site-specific conjugation approaches
• Glycoengineering-enabled conjugation
• Hydrophilic linker technologies
• Novel cleavable and non-cleavable linker systems
• Oligonucleotide and radioligand conjugates
• Dual-payload conjugates
• Develop strategies to optimize payload stability, release kinetics, DAR profiles, manufacturability, and therapeutic index.
• Evaluate emerging payload classes, targeted delivery systems, and novel conjugation chemistries across oncology and adjacent therapeutic areas.

Platform Development & Program Leadership

• Lead scientific strategy and execution across ADC and conjugation platform initiatives.
• Coordinate activities across chemistry, antibody engineering, biology, analytical development, process development, and CMC teams.
• Support candidate selection, developability assessment, and preclinical advancement strategies.
• Partner with external CROs, CDMOs, academic collaborators, and technology providers to accelerate platform and program execution.
• Contribute to program planning, technical risk mitigation, timelines, and milestone execution.

ADC CDMO Scientific SME Responsibilities

• Serve as a scientific subject matter expert (SME) for Xcellon’s ADC and bioconjugation CDMO clients.
• Provide technical leadership and strategic guidance to partners on:
• Conjugation approaches
• Linker-payload selection
• Site-specific conjugation strategies
• Developability assessment
• Process development considerations
• Early CMC and manufacturability strategy
• Participate in technical diligence discussions, client meetings, proposal development, and scientific presentations.
• Support business development activities through scientific engagement with prospective and existing clients.
• Collaborate with internal technical and operational teams to ensure successful execution of client programs.

Innovation & Platform Expansion

• Help establish scalable and differentiated platform capabilities in:
• Linker-payload development
• Conjugation process development
• Purification workflows
• Analytical characterization
• Early CMC and manufacturability assessment
• Identify whitespace opportunities and contribute to intellectual property strategy, invention disclosures, patents, and scientific publications.
• Maintain awareness of the evolving ADC, AOC, RDC, and targeted delivery competitive landscape.

Communication & External Engagement

• Prepare technical presentations, reports, patent disclosures, and development documentation.
• Present scientific findings internally and externally to collaborators, partners, and leadership.
• Support diligence activities, technology evaluations, and strategic partnership discussions.

Qualifications

Required

PhD in Chemistry, Medicinal Chemistry, Chemical Biology, Pharmaceutical Sciences, Biochemistry, or related scientific discipline with 5–12 years of relevant industry experience; or MS with substantial applicable experience.

Deep hands-on experience in one or more of the following:

• ADC linker chemistry
• Payload synthesis
• Bioconjugation technologies
• Site-specific conjugation
• Glycoengineering approaches
• Targeted delivery systems

Strong understanding of:

• Conjugation mechanisms
• Linker stability and payload release
• Drug-to-antibody ratio (DAR) optimization
• Developability considerations
• Translational implications of conjugated therapeutics

Experience with analytical characterization techniques including:

• LC-MS
• HPLC/UPLC
• SEC
• CE
• DAR analysis
• Stability characterization

Proven ability to independently design experiments, interpret complex datasets, and solve technical challenges.

Strong communication, collaboration, leadership, and project management skills.

Ability to effectively communicate complex scientific concepts to both technical and business stakeholders.

Preferred

• Experience advancing ADC, AOC, RDC, or conjugated biologic platforms in an industry setting.
• Prior experience supporting external clients, strategic collaborations, or CDMO/CRO programs.
• Familiarity with payload classes including:
• Tubulin inhibitors
• Topoisomerase inhibitors
• Immune agonists
• Radioligands
• Oligonucleotide payloads
• Experience with process development, scale-up, or manufacturing support for conjugated therapeutics.
• Knowledge of PK/PD, translational pharmacology, and IND-enabling development activities.
• Track record of publications, patents, or platform innovation in conjugation sciences.
• Prior experience working in fast-moving biotech or platform technology environments.

Why Join Xcellon

• Opportunity to help build and shape next-generation conjugation and ADC platforms from the ground up.
• Highly collaborative and entrepreneurial environment with significant scientific ownership.
• Exposure across discovery, platform innovation, translational science, client-facing technical leadership, and CMC development.
• Ability to work on cutting-edge therapeutic modalities spanning ADCs, multispecifics, oligonucleotide conjugates, and targeted delivery technologies.
• Opportunity to contribute directly to platform IP creation, strategic collaborations, CDMO growth, and future therapeutic programs.