Developing a new cancer medicine is often measured in years rather than months.
On July 14, Ugandan scientist Matthias Magoola reached one of those milestones when the U.S. Food and Drug Administration outlined the next steps for his company’s proposed lower-cost version of a widely used cancer treatment.
The FDA sent Magoola detailed comments on PSI-033, a product that his company, Dei BioPharma, is developing as a lower-cost alternative to Yervoy, an immunotherapy medicine sold by Bristol Myers Squibb.
The comments came before a meeting scheduled for July 22 between the regulator and Dei BioPharma, which Magoola founded. He is expected to lead the company’s delegation. The development does not mean that PSI-033 has been approved.
Rather, the FDA has advised the company on the evidence, manufacturing standards and studies it may need before applying for permission to sell the medicine in the United States.
That distinction is important. Drug development can take years, and many products do not make it through testing and regulatory review. But early guidance can save a company time and money by identifying weaknesses before it begins costly studies. PSI-033 is being developed as a biosimilar to Yervoy.
A biosimilar is a biological medicine designed to work in essentially the same way as an already approved product, with no meaningful differences in safety, purity or effectiveness. Unlike ordinary generic tablets, biological medicines are made using living cells and are difficult to copy exactly.
Regulators therefore require extensive laboratory comparisons and, in some cases, clinical studies before approving a biosimilar. Yervoy’s active ingredient, ipilimumab, helps the immune system recognise and attack cancer cells.
It is used in the treatment of several cancers, but such biological medicines are often expensive and remain beyond the reach of many patients and health systems. According to Dei BioPharma, the FDA indicated that several elements of its proposed development programme appeared achievable.
These included the medicine’s formulation, plans for testing how it remains stable over time, studies showing that the manufacturing process removes viruses, and a strategy based on producing three consecutive commercial- scale batches in 500-litre vessels.
In simple terms, the regulator wants evidence that the company can repeatedly manufacture the same high-quality product at a scale large enough for the market. The FDA also indicated that an animal study might not be necessary if laboratory evidence demonstrates that PSI-033 is highly similar to Yervoy.
A separate clinical study measuring the drug’s effectiveness might also be avoided if detailed analytical comparisons and a pharmacokinetic study show no clinically meaningful differences.
Pharmacokinetic studies examine how a medicine moves through the body, how it is absorbed, distributed and eventually removed. Avoiding unnecessary animal and clinical efficacy studies could shorten development and reduce costs.
However, Dei BioPharma would still have to justify that approach when submitting a future licensing application. Because ipilimumab can cause serious side effects when the immune system attacks healthy organs, the FDA advised the company not to conduct its pharmacokinetic study in healthy volunteers.
It also asked Dei BioPharma to collect enough safety information to assess those risks in every treatment group.
“The FDA’s detailed preliminary comments give us a clear, product- specific roadmap for strengthening the analytical package, completing the clinical-pharmacology programme and preparing PSI-033 for a future US licensing application,” Magoola said.
“We intend to address these recommendations with urgency and scientific rigour.”
The commercial stakes are considerable. Bristol Myers Squibb reported approximately $2.9 billion in worldwide Yervoy sales in 2025, a 15 per cent increase from the previous year. Dei BioPharma said the FDA currently lists no approved ipilimumab biosimilar, potentially giving early developers access to a large market.
That opportunity is not guaranteed. Dei BioPharma’s prospects will depend on how quickly it completes its studies, whether rival companies file competing applications and, ultimately, whether the FDA is satisfied with its evidence.
The company is also developing a proposed biosimilar to Opdivo, another Bristol Myers Squibb cancer medicine that generated about $10 billion in sales in 2025.
“Our engagement with FDA extends beyond PSI-033,” Magoola said.
“This portfolio approach is central to our objective of building globally competitive biologics-development and manufacturing capacity in Uganda and expanding access to important medicines.”
“Our dream of making biological drugs available and affordable to more than 80% of countries who cannot afford these medicines is coming to fruition,” he added.
Dei BioPharma says it aims to submit an application for PSI-033 within about nine months, provided it completes the remaining laboratory and clinical work and remains aligned with the FDA.
