ImmuCell Pivots to First Defense® After FDA Halts Re-Tain® Drug

PORTLAND, Maine – December 24, 2025 – Animal health company ImmuCell Corporation announced a significant strategic pivot today, pausing all further investment in its new mastitis treatment, Re-Tain®, after receiving an “Incomplete Letter” from the U.S. Food and Drug Administration. The company will instead redirect its resources to aggressively expand its flagship First Defense® product line, a market leader in preventing scours in newborn calves.

The decision, announced on Christmas Eve, marks a decisive turn for the Nasdaq-listed company (ICCC), trading a lengthy and uncertain regulatory battle for a focused investment in its proven and profitable core business. ImmuCell plans to immediately increase its First Defense® field sales force by 50% and initiate a major expansion of its manufacturing capabilities.

The High Cost of a Third-Party Failure

The FDA’s decision, delivered on December 23, centered not on ImmuCell’s own work but on the shortcomings of a third-party partner. In its New Animal Drug Application (NADA) for Re-Tain®, ImmuCell had successfully cleared four of the five required Technical Sections. The final hurdle related to the product's manufacturing process.

ImmuCell had adopted a dual-pronged approach to limit capital expenditure. It manufactured the active pharmaceutical ingredient for Re-Tain® in its own facility, which passed FDA inspection in 2024. However, it hired an experienced contract manufacturer for the final step: aseptically filling the product into syringes. According to ImmuCell, the FDA’s letter stemmed from this contract manufacturer’s failure to “satisfactorily address inspectional deficiencies.”

This reliance on an external partner, a common practice in the pharmaceutical industry to manage costs and leverage specialized expertise, proved to be the application's undoing. The impending expiration of ImmuCell’s contract with the manufacturer in March 2026 added a time-sensitive pressure, making the prospect of resolving the deficiencies a protracted and impractical endeavor. Rather than get mired in delays, ImmuCell’s leadership opted for a clean break.

“While it is disappointing news that we will be unable to achieve NADA approval with this contract manufacturer, this has only strengthened our resolve to allocate our resources to our highest return opportunity, namely First Defense®,” said Olivier te Boekhorst, President and CEO of ImmuCell, in a statement.

Doubling Down on a Market Leader

With the Re-Tain® project on hold, ImmuCell is channeling its full force behind the First Defense® franchise. The company’s confidence is bolstered by the product line's dominant market position and consistent performance. First Defense® is the #1 ranked product for preventing scours (calf diarrhea) in the United States, commanding an impressive 29% market share, according to the 2025 Hoard’s Dairyman Continuing Market Study.

The product line, which provides immediate immunity to newborn calves through hyperimmunized colostrum, has been a powerful growth engine for the company. David S. Tomsche, DVM, Chair of ImmuCell’s Board of Directors, noted its impressive track record. “Fifteen years ago, ImmuCell established a small field team that grew First Defense® annual revenue from approximately $4.4 million then to approximately $27.8 million in the trailing twelve-month period ended September 30, 2025,” he commented. “First Defense®’s record of more than 13% compounded growth per year for more than a decade gives us confidence that focusing on and investing more in First Defense® can deliver strong shareholder value.”

The company is targeting what it estimates to be a $900 million global Total Addressable Market for scour prevention. Market research reports paint an even broader picture, with the global calf scour treatments market valued at over $1.29 billion in 2024 and projected to exceed $2 billion by 2033. This vast market, coupled with high calf values in both the dairy and beef industries, presents a significant runway for growth.

Immediate expansion plans are already underway. ImmuCell is adding two new sales territories in the U.S. and hiring a senior executive to spearhead its international strategy. Simultaneously, a multi-year manufacturing improvement program has been launched to lower production costs, improve yields, and execute a new phase of capacity expansion.

Financial Adjustments and Asset Repurposing

The strategic shift necessitates a financial reckoning for the now-stalled Re-Tain® project. ImmuCell disclosed that it expects to record a non-cash impairment write-down in the fourth quarter of 2025. As of September 30, 2025, the net book value of Re-Tain® assets stood at approximately $15.5 million.

“We are anticipating adjustments to laboratory and manufacturing equipment and construction in progress, resulting in an estimated non-cash impact to profit of approximately $2.3 million,” stated Timothy Fiori, ImmuCell’s Chief Financial Officer. He stressed that the final figure would be determined after a full review.

Crucially, the company does not see this as a total loss. “We plan to repurpose facilities and a large portion of the equipment for the expansion of First Defense® capacity to maximize return on these assets,” Fiori added. This move allows ImmuCell to salvage significant value from its Re-Tain® investment and apply it directly to its new growth focus, mitigating some of the financial sting and accelerating the First Defense® expansion.

While the company has paused its own investment, it is not completely abandoning the Re-Tain® intellectual property. ImmuCell will complete ongoing studies to potentially enhance the product’s treatment claims and will explore licensing it to other parties or partnering with a global manufacturer, effectively outsourcing future development risk.

For ImmuCell, the FDA’s “Incomplete Letter” has become a catalyst for change. By cutting its losses on a problematic project, the company is making a calculated bet on its established star product. With a clear focus and renewed investment, ImmuCell is betting that the future of its herd health empire lies not in a new drug, but in the proven power of its First Defense.