Pharming expands Joenja into children as rare-disease growth offsets RUCONEST pressure

Pharming Group N.V. (Euronext Amsterdam: PHARM; Nasdaq: PHAR) has received U.S. Food and Drug Administration (FDA) approval to expand Joenja, or leniolisib, into children aged four to 11 years with activated phosphoinositide 3-kinase delta syndrome who weigh at least 27 kilograms. The expanded label makes Joenja the first FDA-approved treatment for this pediatric APDS population and adds 40 mg and 50 mg twice-daily doses that Pharming expects to make commercially available during October. The opportunity is numerically small but economically important because Pharming had identified 60 U.S. APDS patients aged four to 11 by June 30, while Joenja revenue was already growing 40% year on year. The approval therefore expands a business that is increasingly important as the company’s older RUCONEST franchise experiences weaker sales and overall guidance has been reduced.

The pediatric approval also comes earlier than the October 24 action date previously assigned to the resubmitted application. Pharming originally received a Complete Response Letter in January 2026, subsequently met with the FDA and resubmitted dosing information covering children weighing at least 27 kilograms. The company still plans another application for patients weighing between 13 and 27 kilograms, meaning the September decision expands access materially but does not yet cover every child with APDS.

Why can a label covering only dozens of identified children matter financially?

APDS is an ultra-rare primary immunodeficiency, so Pharming’s opportunity depends less on large population numbers than on finding individual genetically confirmed patients and maintaining them on chronic therapy. As of June 30, the company had identified 1,042 diagnosed APDS patients globally, including 298 in the United States. Of those U.S. patients, 198 were aged 12 or older and eligible under the previous Joenja label, while 60 were aged four to 11.

Adding even a modest number of pediatric patients can therefore be meaningful relative to the existing commercial base. Pharming reported 132 U.S. patients on paid Joenja therapy at June 30, only a little more than twice the number of identified children in the newly expanded age bracket. Not every identified child will meet the 27-kilogram weight threshold or start therapy immediately, but the ratio illustrates why rare-disease companies can generate material growth from patient groups that appear tiny beside conventional pharmaceutical markets.

The pediatric label also increases the lifetime economic value of successful patient identification because treatment can potentially start earlier rather than waiting until age 12. Chronic rare-disease therapy can produce revenue over many years if efficacy, tolerability and access remain favorable, making earlier diagnosis commercially and clinically important. Pharming’s challenge will be expanding genetic testing and specialist awareness sufficiently to find children before immune complications accumulate.

What exactly does Joenja treat in activated PI3K-delta syndrome?

APDS is a rare genetic immune disorder associated with overactive phosphoinositide 3-kinase delta signaling, leading to immune dysfunction that can manifest through recurrent infections, lymphoproliferation and other serious complications. Joenja selectively inhibits PI3K-delta, targeting the pathway involved in disease rather than treating only individual infections or inflammatory complications. Its initial U.S. approval covered patients aged 12 and older, and the latest supplemental approval brings appropriately weighted children into the same disease-modifying strategy.

That mechanism creates a very different commercial proposition from supportive immune care. Physicians treating genetically confirmed APDS can potentially intervene against the underlying signaling abnormality rather than managing each manifestation separately. The benefit still has to be weighed against chronic treatment requirements and product safety, but regulatory expansion across progressively younger populations can strengthen the drug’s position as the standard targeted medicine for the disease.

Pharming is pursuing that lifecycle strategy internationally as well. Joenja has already launched in Japan for adult and pediatric patients aged four and older, while European commercialization began after authorization for patients aged 12 and above. The U.S. pediatric expansion therefore forms part of a broader effort to turn a highly specialized rare-disease medicine into a geographically diversified franchise.

Why is Joenja becoming more important as RUCONEST slows?

Pharming generated $90.2 million of second-quarter 2026 revenue, down approximately 3% from the year-earlier period. RUCONEST revenue fell 10% to $72.3 million, while Joenja increased 40% to $17.9 million and reached $32 million for the first half, up 37%. Joenja still accounts for a minority of total sales, but its faster growth means the revenue mix is gradually becoming less dependent on the older hereditary angioedema franchise.

The weakness in RUCONEST contributed to Pharming reducing full-year revenue guidance to $375 million to $395 million. Second-quarter operating profit also fell to $1.3 million from $10.8 million a year earlier, underscoring why management needs Joenja growth to become sufficiently large to offset volatility elsewhere in the portfolio. A broader pediatric label cannot solve that challenge immediately, but it increases the number of treatable patients without requiring another drug discovery program.

This dynamic explains why the approval has financial significance despite the rarity of APDS. Pharming is not merely adding another indication to a diversified multinational portfolio. It is expanding one of only two principal commercial franchises at a time when the older product is no longer providing reliable growth.

What is still missing from the U.S. pediatric label?

The current approval is limited to children weighing at least 27 kilograms and uses 40 mg and 50 mg twice-daily dosing. Pharming has been preparing a separate supplemental application for lower-weight children between 13 and 27 kilograms, which would broaden access further if the FDA ultimately agrees that the proposed lower doses are appropriate. The distinction matters because referring simply to “children aged four to 11” without the weight threshold would overstate the scope of the new authorization.

This staged approach reflects the pharmacokinetic complexity of pediatric drug development. Younger or lighter children may require different dosing to achieve exposures comparable with older patients while avoiding excessive concentrations. Securing approval for the heavier pediatric group first gives Pharming commercial expansion while leaving the company with another identifiable regulatory catalyst.

The next lower-weight filing also represents additional organic growth that does not require acquiring another product. For a company operating in very small patient populations, adding a few dozen additional eligible patients across the United States, Europe and Japan can meaningfully change the long-term sales trajectory.

How did PHAR shares respond to the earlier-than-expected pediatric approval?

Pharming’s Nasdaq-listed American depositary shares closed at $11.21 on September 11, up 3.75%, after trading as high as $11.69 during the session. That gain reversed part of a 4.6% decline two days earlier but left the stock below its August 28 close of $11.70, suggesting investors welcomed the approval without treating it as a company-transforming surprise.

The measured reaction fits the economics. Joenja is growing quickly and pediatric expansion improves its runway, but Pharming still has to rebuild consolidated growth while managing RUCONEST volatility, investing internationally and progressing pipeline programs. The stock is consequently likely to respond more strongly to evidence that Joenja can keep compounding across geographies and age groups than to each individual label extension.

For Pharming, the September approval moves that strategy one step forward. Joenja is no longer only a therapy for adolescents and adults in the United States, and its addressable population will expand further if the lower-weight application succeeds. The next investor question is whether those additional patients can make Joenja large enough to become the company’s dominant growth engine rather than simply its fastest-growing smaller product.