About Tr1X

Tr1X is a clinical-stage biotechnology company developing engineered Tr1 cell therapies to restore immune balance in autoimmune and inflammatory diseases. Leveraging the unique biology of Tr1 cells, the company is advancing a pipeline of off-the-shelf allogeneic and in vivo CAR-Tr1 therapies designed to deliver targeted immunoregulation and address diseases driven by immune dysfunction, including transplant-related complications. Founded by pioneers in the discovery of Tr1 cells, Tr1X, Inc. is focused on developing durable, potentially curative therapies for conditions with high unmet need. For more information, visit www.tr1x.bio.

Position Summary

The Senior Scientist, In vivo Immunology – Targeted LNP Delivery is an experienced, hands-on immunologist who leads the biological design and evaluation of targeted lipid nanoparticle (tLNP) formulations supporting the Tr1X in vivo chimeric antigen receptor (CAR)-Treg platform. Reporting to the Executive Director of Biology, this individual plays a central R&D role in advancing tLNP delivery systems — defining the immunological targeting rationale and driving in vitro and in vivo proof-of-concept studies — to enable precise, immune cell-specific delivery of nucleic acid payloads.

This is a high-impact, science-driven role focused on the discovery and development of Tr1X’s next-generation tLNP delivery platform. The Senior Scientist brings deep expertise in immunology, particularly T cell and Treg biology, hands-on experience applying tLNPs in immune cells, strong experimental rigor across in vitro and in vivo studies, and the ability to thrive in a fast-paced startup environment.

Key Responsibilities

• Partner with formulation and chemistry colleagues on the design and optimization of targeted lipid nanoparticle (tLNP) formulations for mRNA payloads, owning the immunological targeting criteria and biological evaluation.
• Design and execute in vitro and in vivo studies, including humanized models, to evaluate tLNP targeting specificity to defined immune cell subsets, biodistribution, potency, and functional delivery of payload within the Tr1X in vivo CAR-Treg platform.
• Design and apply multiparameter flow cytometry and immunophenotyping assays to characterize tLNP uptake across immune cell subsets, targeting specificity, and downstream functional readouts such as transgene expression and suppressive activity.
• Develop and apply analytical characterization methods (e.g., DLS, encapsulation efficiency, fluorescence-based assays) as needed to support formulation and conjugation research.
• Interpret analytical, in vitro, and in vivo data to establish structure-function relationships between tLNP formulation/conjugation attributes and biological performance.
• Collaborate closely with platform biology, in vivo pharmacology, and process development colleagues to advance candidate tLNP formulations from discovery through early development, and to inform downstream manufacturability considerations.
• Prepare study reports, presentations, and technical documentation summarizing research findings for internal stakeholders.
• Stay current with emerging science in immune cell-targeted LNP delivery, Treg and lymphocyte biology, and nucleic acid therapeutics, and contribute new ideas to platform strategy.
• Perform other responsibilities as required based on business needs.

Required Qualifications & Experience

• Ph.D. in Immunology or a closely related discipline, with 4+ years of relevant industry or academia experience, with industry or a combination of industry and academia experience preferred. Direct, hands-on immunology research experience is required.
• Demonstrated hands-on experience applying targeted lipid nanoparticles (tLNPs) for cell-specific delivery to immune cells, including design of targeting strategies and evaluation of delivery in primary cells.
• Working familiarity with LNP formulation for mRNA or other nucleic acid payloads sufficient to collaborate effectively with formulation scientists.
• Strong understanding of immunology, with specific experience in lymphocyte biology and in vivo disease models
• Highly organized, scientifically rigorous, and capable of independently driving projects while collaborating effectively in a multidisciplinary startup environment.
• Excellent written and oral communication skills.
• Strong analytical and problem-solving skills, with great attention to detail and the ability to drive timely, fact-based decision making.
• Ability to function in a rapidly changing environment and manage multiple priorities.

Preferred Qualifications

• Experience with flow cytometry for cell-based assay characterization and evaluation of tLNP uptake and targeting.
• Expertise designing and executing in vivo mouse studies, including dosing, biodistribution, and efficacy studies.
• Top-tier written, verbal, and interpersonal communication skills, with strong organizational skills and attention to detail.
• Prior experience with Treg, CAR-T, or other engineered cell therapy and immunotherapy platforms.
• Experience correlating formulation or conjugation attributes with in vivo performance.

Other Requirements

• Legally authorized to work for any employer in the U.S.
• Position is onsite in San Diego

The job responsibilities and requirements provided above are intended to describe the general nature of the work performed by individuals assigned to this job classification. It is not intended to be an exhaustive list of all duties and requirements. Tr1X retains the right to add, change, or delete duties, education, experience or any other requirements of the position at any time.

Working at Tr1X

At Tr1X, our team is united by a singular shared mission: to transform patients’ lives through breakthrough science. We are a group of skilled experts driven by urgency, innovation and a collaborative spirit. Our culture thrives on excellence, positivity, persistence and the agility to tackle new challenges head-on. With an unwavering commitment to patients, science and one another, we foster an environment where team members feel engaged, supported and empowered to make a meaningful impact. We envision a world where autoimmune diseases are not just being treated but are cured.

Base Pay Range Anticipated: $152,000 - $165,000

Tr1X considers a variety of factors to determine salary such as education, years of experience, time in the position level, training, knowledge, skills, geographic location, and the market value of the position.

Compensation and Benefits

Tr1X provides a fair and competitive total rewards program that includes base salary; discretionary annual target bonus; incentive stock options; 401(k) retirement plan with company contribution; health and welfare insurance plans for employees (and their families) that include medical, dental, vision, long-term and short-term disability, and life insurance; paid time off (PTO); and paid holidays.

Tr1X embraces a diverse, open, and inclusive environment and believes a strong culture connection is key to success. Tr1X is committed to fairness in recruitment, hiring, transfer, promotion or any other employment practice without regard to race, color, citizenship, national origin, ancestry, religion, sex, pregnancy, marital status, sexual orientation, gender, gender identity and expression, age, physical and medical disability, medical condition, genetic information, political affiliation, protected veteran status, or any other characteristic protected by law. If you are an individual needing assistance to complete an employment application or would like to request an accommodation, please contact the Human Resources department at [email protected].

Notice to Employment Agencies

The Tr1X talent acquisition program is managed through internal resources, and unsolicited referrals and resumes are not accepted from employment agencies, unless advance written authorization is granted from the human resources department. Tr1X shall not be liable for any fees arising from any unsolicited or unauthorized candidate information received relative to position vacancies.