Pfizer validation engineer, peer-reviewed author, and ASTM Committee E55.06 voting member Prasantha Pujari on solving qualification challenges where biologics meet cytotoxic drugs — and why the frameworks he built for PADCEV are now published for the field
Antibody-drug conjugate contract manufacturing hit $1.72 billion this year and will nearly double to $3.2 billion by 2035, according to the market research firm Roots Analysis. Manufacturing these cancer treatments creates headaches for validation engineers because you’re combining two completely different production worlds – antibody biologics that need sterility, and cytotoxic chemicals that need containment. Existing qualification playbooks weren’t written for facilities doing both at once.
Prasantha Pujari served as a validation engineer at Seagen and Pfizer Oncology, where he qualified equipment for the FDA-approved ADC, PADCEV. His work contributed to a successful pre-approval inspection with zero observations within his scope. Pujari’s autoclave qualification methodology was adopted as a site-wide SOP and training standard at Pfizer North Creek, and has since been published in a peer-reviewed journal and a technical manual. A voting member of ASTM Committee E55.06, he also served as a jury member for the 2026 Cases & Faces International Business Award. Pfizer recognized his contributions with six awards, including a Global Supply Certificate of Recognition. We discussed the unique challenges of applying standard validation to ADC manufacturing.
Prasantha, you led equipment qualification for PADCEV at Pfizer Oncology, a product that required FDA pre-approval inspection. Walk me through what made ADC validation different from regular pharmaceutical work.
Standard pharma facilities do one thing – either biologics or small molecules. Biologics plants are concerned about sterility and minimizing bioburden. Chemical plants prioritize containment and protection of workers from exposure. ADC facilities perform both functions in the same building, sometimes in adjacent spaces. That creates qualification scenarios where standard templates fall apart. Take autoclaves. Normally, you’re proving sterility for biologics. But in ADC work, you’re sterilizing equipment that’s been exposed to cytotoxic materials, so containment during the cycle matters too. Water for injection has to meet biologics purity specs while preventing cytotoxic cross-contamination. Compressed gases touch both biological and chemical processing areas. Nothing in the standard protocols covers dual-risk scenarios like that. We were conducting this for a pre-approval inspection, where documentation gaps are identified as critical findings rather than observations.
Your switch from biological indicator ampoules to strips for autoclave qualification became part of Pfizer’s standard practice and cut repeat testing by about a third. What problem were you solving?
BI ampoules are rigid glass tubes, so you place them where they fit easily: good spacing, accessible spots, and convenient locations for retrieval. Works great for test runs. But our actual production loads looked nothing like that. We had irregularly shaped containers, nested equipment, and tight corners where glass ampoules physically couldn’t go. I kept looking at our qualification data showing sterility in convenient locations, then looking at production loads where the real contamination risks were in spots we’d never tested. QC confirmed it—they had areas in their loads that our qualification protocols completely missed. Strips are flexible, you can conform them to irregular surfaces, and slide them into tight spaces. But you can’t just swap them in. We had to validate strips against ampoule performance, write new placement protocols, and document the risk-based rationale for the change. Implementation took effort, but repeat testing dropped about a third because we were getting usable data on first runs instead of finding placement problems after failures. I also published the underlying methodology in a peer-reviewed journal, so that other ADC facilities working through the same problem have a documented framework to reference rather than building it from scratch.
Your refrigerated incubator qualification method is now the site standard at Pfizer North Creek and reduced temperature-related deviations. How did your approach differ from what was being done before?
The standard qualification treats incubators as standalone equipment. Empty chamber, temperature sensors in a grid pattern, check that alarms work, verify it holds the setpoint. That proves the box functions, but it doesn’t tell QC what they need to know, will my samples stay stable the way I’m actually using this equipment? We were qualifying hardware when the real question was about process performance. Sample stability isn’t just about setpoint. Shelf position matters because vertical temperature distribution varies. How often you open the door affects recovery time, which changes your real hold time limits. Load density alters airflow. The empty-chamber qualification captured none of that. So I redesigned it around load simulation – mapped temperatures where samples actually sit, tested door opening at real-use frequencies, and matched load density to typical operations. Turns out vertical positioning had bigger effects than anyone expected. Recovery patterns completely changed based on how samples were arranged. Once we had data from actual conditions, QC got real hold times instead of overly conservative estimates that created workflow bottlenecks. Temperature deviations decreased because we understood what the system actually did, rather than what the empty-chamber theory predicted. This qualification design was adopted as the site standard at North Creek through the formal change control process. QA reviewed the load simulation methodology, the door-opening test protocol, and the vertical mapping approach, and accepted them as the governing qualification framework for incubators at the facility. The meaningful outcome wasn’t that one engineer redesigned a qualification – it’s that an independent QA review validated the redesign and the site committed to it.
Between autoclaves, incubators, water systems, and compressed gases, how did you keep all these qualification projects moving while prepping for inspection?
Validation becomes a bottleneck the moment engineering decides to work alone. I learned to pull in operations, QC, and QA before writing protocols, not after. For the controlled temperature units that move materials around, I asked operations how they actually used the equipment, had QC map out their critical sampling points, and obtained QA’s documentation requirements upfront. Built all that into the qualification design before locking anything down. Takes more time at the start, but you avoid rework cycles when validation doesn’t match reality. People understand what you’re testing and why, so results actually serve their needs instead of just satisfying regulators. Inspection preparation became easier because our validation data came from real manufacturing practices; auditors could see that we weren’t just checking boxes, but were generating data that operations and QC actually relied on.
Looking at the bigger picture, what changed about ADC validation at Pfizer based on your work there?
The biggest thing was fixing the gaps, causing delays in protocol reviews and inspection prep. The BI strip approach I mentioned is no longer how we handle mixed ADC loads, because it provides better sterility data for cytotoxic biologic materials. Reduces retesting, making cycle development more predictable. The incubator qualification method added mapping points aligned with QC needs, recovery testing under realistic conditions, and load simulation that matched actual use. Earlier versions only examined equipment specifications, but ADC materials require tighter control than that. These methods were applied across the whole qualification scope: autoclaves, CTUs, incubators, WFI, and compressed gases. The protocol rework went smoothly, audit readiness improved, and inspection reviews proceeded more smoothly because our data matched what regulators expect to see at biologic-cytotoxic facilities.
Pfizer gave you multiple awards during this period: Bravo Awards, an Excellence Award, and a Certificate of Recognition. What validation work earned those distinctions?
Bravo Awards came from finishing high-priority qualification work on tight deadlines and supporting audit prep. Got an Excellence Award for inspection readiness and closing out critical projects. The Certificate of Recognition was issued by Pfizer Global Supply for the Empower 3.8.1 CDS system deployment, a site-wide chromatography data system transition affecting QC operations for ADC manufacturing. These recognize contributions to manufacturing reliability, regulatory compliance, and inspection performance. I became the person teams asked for when qualification issues arose, when requalification planning was needed, and when audit documentation required support.
Where are you headed next with validation work?
The direction I’m moving is from site-level execution to standards-level contribution. I’ve already published one component of that, a technical manual on risk-based autoclave steam sterilization cycle design for mixed biopharmaceutical loads, available on Amazon through Notion Press. It positions the methodology I developed for PADCEV as a replicable framework other ADC facilities can apply directly, without having to build the rationale from scratch. I’ve also published two peer-reviewed papers: one on the autoclave methodology itself, and one on deviation management in pharmaceutical quality systems. On the standards side, I recently became a voting member of ASTM International Subcommittee E55.06 on Microbial Contamination Control, part of Committee E55 on the Manufacture of Pharmaceutical and Biopharmaceutical Products. My classification was reviewed by the responsible committee officer, an industry representative from Moderna. Earlier this year I served as a jury member at the Cases & Faces International Business Award in Fort Lauderdale, evaluating submissions in medical devices and health technology. The event drew more than 1,000 participants from 16 countries. Being asked to judge innovation in regulated medical technology from a validation and quality-systems perspective is a natural extension of this work – the same analytical framework that makes equipment qualification defensible also makes it possible to evaluate whether a product claim is grounded in real-world execution.
