Downstream Process Engineer (Purification)

Airtree recently invested in an early stage biologics company. Currently in stealth, they exist to make biologics radically cheaper, so modern medicine reaches the people today's industry prices out, across both human and animal health. 

Discovery got cheap; manufacturing didn't, and the cost of making antibodies is now what keeps them from patients. That's the constraint we exist to break. We're building factories that deliver a 20–50x cost reduction at scale: more than 10 tonnes of drug substance a year, at under $10 a gram. Think of it as a foundry, a standardised platform that molecules adapt to, rather than a contract manufacturer running a bespoke process per client.

Our founding team has done a version of this before and we're building this company on the same engineering playbook, and hiring the people who'll make it real. We're looking for a Downstream Process Engineer to own purification process development, the biggest cost and learning gate in the whole train.

We make antibody therapeutics cheaper by standardising the hard, learning-heavy parts of the process, and downstream purification is where most of the cost and most of the learning sit. Protein A purification alone drives a large share of cost of goods. We need someone to own the downstream: take a molecule in, design a first-pass purification process on it, and get it to the quality bar at the lowest cost we can.

In your first 3-6 months, success looks like taking multiple antibodies through first-pass purification development, identifying the major cost, yield and purity trade-offs, and helping bring our first process-scale downstream equipment into reliable operation.

• Adapt each biologic molecule to our platform purification process: identify candidate parameters, weigh the trade-offs between yield, purity and cost, and find the process we could run at scale. Turn that into a re-usable workflow.
• Improve the platform with every program: learn where the default works well and where the gaps are, and iterate towards a robust platform that minimises cost and reduces bespoke development over time.
• Work with our analytics team to develop effective screening approaches that evaluate clearance success and quality metrics without running time-consuming methods at every step.
• Your first focus will be the core downstream train: making Protein A capture repeatable, scalable and cost-effective, then defining the simplest polishing strategy that gets each molecule to the quality bar.
• Get us run-ready. Process-scale equipment is arriving soon, and you'll help design and de-risk operating it.
• Run proper experimental design: elution windows, wash optimisation, buffer conditions, hold studies. You read chromatograms like you mean it.
• Work shoulder to shoulder with upstream and analytics, so the process you design survives contact with real broth.

Essential

• A PhD or Masters in chemical engineering, bioprocess engineering or a closely related field, or equivalent hands-on industry experience.
• Real downstream / purification experience: chromatography (Protein A, ion exchange), filtration (TFF, UF/DF), and buffer and process design. Hands-on with FPLC / ÄKTA.
• Hungry, hands-on and scientifically rigorous. You want to own process development at scale, not stay at lab-bench scale.
• Comfortable at a very fast pace in a small, high-ownership team. You make calls on incomplete data and own the outcome.

Nice to have

• mAb / biologics experience.
• Membrane chromatography exposure.
• Analytics literacy: SEC-HPLC, HCP ELISA, cIEF.
• Tech-transfer or GMP exposure.