Blue Lake Biotechnology to Resume Enrollment of RSV-negative Toddlers in Phase 1/2a Clinical Trial of BLB201

FDA clarifies path forward for ongoing development of Blue Lake’s industry-leading pediatric RSV vaccine

Blue Lake Biotechnology, Inc., a clinical-stage intranasal vaccine company developing parainfluenza virus 5 (PIV5)-vectored vaccines that harness the full breadth of the immune system to protect against serious infectious diseases, today announced that it has secured written agreement from the U.S. Food and Drug Administration (FDA) to resume dosing of BLB201, the company’s investigational RSV vaccine, in children as young as 18 months who are RSV-negative as well as those who are RSV-positive.

As disclosed during FDA’s Vaccines and Related Biological Products Advisory Committee meeting in December 2024, FDA had placed clinical holds on pediatric RSV vaccine trials to exclude the enrollment of children who tested negative for RSV exposure (RSV-negative) or who were under two years old. The holds resulted from a safety signal found in another company’s clinical trial of an mRNA-based RSV vaccine, where suspected cases of vaccine-associated enhanced respiratory disease (VAERD) were reported.

Since the placement of clinical holds on pediatric RSV vaccine trials, Blue Lake has been engaging with FDA on the ongoing development of BLB201 as a pediatric RSV vaccine. “FDA’s lifting of the partial clinical hold on our trial is an important step that clears a path for Blue Lake to continue to develop an RSV vaccine for toddlers,” said Biao He, Ph.D., CEO of Blue Lake Biotechnology. “In our interactions with the FDA, the agency also recognized that there has been no evidence suggesting that BLB201 causes VAERD.”

During the partial clinical hold period, Blue Lake was allowed to continue enrolling RSV-positive children over two years old. The lifting of the partial clinical hold follows a recent Type C meeting with FDA and allows for enrollment of children as young as 18 months regardless of RSV serostatus, enabling development of BLB201 for use in toddlers, and making possible future development in even younger children including infants.

“The enrollment of additional seronegative and younger toddlers will enable us to further evaluate the safety of BLB201 in children who have not been exposed to RSV and who have the greatest potential to benefit from a pediatric RSV vaccine. We also hope to expand our analysis of the clinical benefits of BLB201 in protecting children from symptomatic RSV infection as well as severe RSV infection. These safety and efficacy data will be the foundation for the development of the first RSV vaccine for toddlers,” commented Dr. Henry Radziewicz, Chief Medical Officer of Blue Lake Biotechnology. “In light of recent setbacks in trials sponsored by other RSV vaccine developers, BLB201 now represents the most advanced pediatric RSV vaccine for young children in clinical development.”

Prior to the onset of the partial clinical hold, Blue Lake had enrolled 63 participants in the Phase 1/2a study of BLB201 ranging from 8 to 59 months old, of which over one-third were RSV-negative. A preliminary analysis of partially unblinded data in December 2024 showed that across the entire study population, children who received BLB201 were 80% less likely to contract symptomatic RSV infections than children who received placebo (p<0.05). In addition, the vaccine has shown excellent tolerability and safety to date across all participants enrolled in clinical studies of BLB201.

About RSV

Respiratory syncytial virus (RSV) is a highly contagious and common respiratory virus and one of the leading causes of acute respiratory disease, infecting more than 64 million people worldwide per year. For most people, it causes symptoms similar to the common cold, but for infants, the immunocompromised, people with chronic heart or lung disease, and older adults, it can cause severe illness and be life-threatening. Repeat infections with RSV are believed to be common, so even people who contracted RSV when they were younger adults and healthy can be at risk from RSV infection later in life. According to the Centers for Disease Control, up to 80,000 children under five years old and up to 180,000 older adults are hospitalized per year because of RSV infection in the US, with up to 10,000 deaths each year.

While there are approved antibody drugs and a maternal RSV vaccine that can provide passive immunity against RSV to infants, there is no approved vaccine for generating prophylactic immunity against RSV in infants and children. Such a vaccine is needed to fully protect young populations at significant risk from severe RSV disease.

About BLB201

BLB201 is an RSV vaccine candidate that is being evaluated in Phase 1/2a clinical testing in children ages eight to 59 months of age. It has received Fast Track designation from the US Food and Drug Administration for the prevention of RSV-associated acute respiratory disease in adults (>60 years) and pediatric populations. BLB201 encodes the RSV F protein and uses a proprietary PIV5 vector, which is not known to cause human disease. PIV5 has been commonly administered to dogs as part of combination distemper/kennel cough vaccines for decades. Blue Lake Biotechnology is developing BLB201 as an intranasal vaccine to prevent acute and severe disease associated with RSV infection. Phase 1 clinical trial results demonstrate BLB201's safety and ability to induce antibody and cell-mediated immune responses, positioning it as a promising candidate in the fight against RSV.

About Blue Lake Biotechnology

Blue Lake Biotechnology, Inc. and its affiliate, CyanVac LLC, are developing intranasal vaccines that harness the full breadth of the immune system to keep people healthy, prevent serious infectious diseases, and protect the health of vulnerable populations. Our platform mimics natural infections by expressing a protein from a targeted pathogen in a proprietary parainfluenza virus 5 vector. Clinical data have shown that administration of our intranasal vaccine candidates stimulates all three pillars of the immune system, including mucosal immunity, which may be beneficial in preventing transmission of pathogens and spread of disease. We have a robust clinical-stage pipeline of best-in-class vaccines designed to overcome the limitations of existing vaccine technologies. Our lead product candidates have demonstrated potential for efficacy against symptomatic infection following a single intranasal dose, with few vaccine-related side effects.

Learn more at Blue Lake Biotechnology.

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