Know Your Cost of Goods Recap and Managing Lot Size Estimation

Know Your COGs Webinar Recap

Commercializing a living cellular product can be a very daunting endeavor for any cell therapy product developer. It is a complex process that requires good planning, distinct expertise, and valuable experience. Specifically, strategic product & process development is a unique discipline that while not taught in University, can greatly reduce risks in the face of short timelines and limited funding. This is a skill set best learned on the job, it is very technical, and it serves as a key strategic component often overlooked in the overall therapeutic product development.

In the spirit of sharing good science and best practices that everyone can benefit from, the RoosterBio team kicked off a webinar series on Best Practices in RegenMed Product and Process Development. The first webinar we hosted was on Know your Cost of Goods (COGs), demonstrating through real-world example how process and material decisions made today might impact your COGs for years to come. In this educational 45-minute webinar (click here to watch webinar if you missed it), our Global Product Manager, Dr. Joseph Candiello explains why an early strategic focus on understanding your COGs can be used as a guide during your product and process development; enabling  you to efficiently allocate resources and set priorities during development while driving towards a sustainable business model. This includes building the process flow diagram based on your understanding on estimating the lot size ranges as well as manufacturing platforms you need to meet your unique therapeutic goals. We have previously published 2 detailed blogs on those topics here and here, and more on lot size estimation will be elaborated in the next section.

Next, Dr. Candiello provided a comprehensive step-by-step overview on how to build and use a process cost model for a product under development, and how process changes can have major downstream COGs implications. In the case study, Dr. Candiello detailed each process change with a comprehensive cost breakdown, cost metrics, and productivity metrics that can help the end user identify the largest cost drivers. The case study also demonstrated the importance of seeking out solutions that carry both quality and productivity improvements. He concluded that early cost modeling is beneficial in that it can focus strategic efforts during product and process development and significantly reduce commercialization risks for the company.

This COGs webinar is really the first of our RegenMed Product and Process Development webinar series aimed to provide a framework towards scalable, cost effective manufacturing which we believe helps in building sustainability business models.

Watch Know Your COGs Webinar

Lot Size Estimation – Why is it Important?

A common pitfall that cell therapy product developers and production managers can make is underestimating how many cells to manufacture for their current and future business needs. This not only leads to under budgeting their manufacturing costs but also undermines the progress of their process development programs. To avoid making such “costly” mistakes, it is absolutely critical to understand how to correctly estimate human mesenchymal stromal cell (hMSC) lot size ranges for clinical manufacturing (here) and make technology platform decisions based on lot size (here).

How to Estimate Your Lot Size Requirements

To correctly estimate your hMSC manufacturing lot size, you must make the appropriate assumptions to guide these calculations. As a quick recap from our previous blog, here are the key aspects you must know and account for when performing lot size estimation:

  • Cell recovery loss – This is the amount of cell loss due to cryopreservation
  • Viability loss / drop – This is the drop in viability post-thaw, typically 10% and in worse case 15%
  • Post-harvest cell loss – During harvest, whether in culture flask or bioreactors, and downstream processing, you will experience some cell loss associated with every unit operation.
  • Percentage of log for testing (%) – A percentage of the manufacturing lot that will go to log testing, typically 10%

Understanding your process to get a good estimation for these factors is one of the critical things that production managers and process engineers must do to be able to make appropriate assumptions for determining their lot sizes and manufacturing batches. Once you nail this, you can design product quality into every single lot.

To make it easier, you can use this simple calculator tool that we have created to estimate cell lot sizes and manufacturing batch sizes.

Final Tips and Pointers

Consistency of product performance must be retained in each lot. Note: A lot, as defined by the US FDA, “means a batch or a specific identified portion of a batch, having uniform character and quality within specified limits” (see link).

Estimating manufacturing batch size is important for technology platform selection which provides an estimation of the production cost required at each stage of a clinical development program. This is important for smaller companies raising capital needed to complete their clinical program.

More importantly, understanding your process leads to better control of your final product performance which will ultimately be delivered to the patient. High product variability can impact clinical outcomes, which can also lead to higher risks of trial failures at later stages.


We're fueling the rapid commercialization of scalable regenerative cures. If you're interested in having a conversation about how RoosterBio can accelerate your product & process development and shorten your time to the clinic, contact us.