GSK Halts Phase 2 Pediatric RSV Vaccine and Reports Feladilimab Failure in Lung Cancer Trial

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On July 28, GlaxoSmithKline (GSK) released its second-quarter financial results, reporting sales of £8.1 billion, up 6% year-on-year on an actual exchange rate (AER) basis. By division, Pharmaceuticals sales were £4.2 billion, up 3% year-on-year on an AER basis; Vaccines sales were £1.6 billion, up 39% year-on-year on an AER basis; and Consumer Healthcare sales were £2.3 billion, down 4% year-on-year on an AER basis.

In the financial report, the company also disclosed that it has discontinued a pediatric respiratory syncytial virus (RSV) candidate vaccine (viral vector) in Phase II clinical development, following an evaluation indicating that the vaccine's efficacy in protecting children is unlikely to meet the target value.

This RSV pediatric vaccine, named GSK3389245A (also known as ChAd155 RSV), is a recombinant chimpanzee adenovirus vector vaccine co-developed by GSK and the Oxford Vaccine Group, which is also renowned for its collaboration with AstraZeneca in developing the COVID-19 vaccine. The GSK3389245A vaccine is based on three RSV viral proteins encoded by the viral vector and is expected to stimulate the immune system to elicit both humoral and cellular immune responses against the pathogen.

GSK initiated a Phase 1/2 trial in 2016 targeting RSV-positive infants aged 12–23 months. Another Phase 1/2 trial for infants aged 6–7 months was launched in 2019; the infants enrolled in this trial had a very low likelihood of prior RSV exposure, and the trial was essentially completed in January 2020.

These are the studies to date on the application of GSK3389245A as a prophylactic therapy for RSV in the pediatric population. GSK disclosed in its second-quarter earnings report released on Wednesday that it has discontinued the development of the RSV pediatric vaccine after an assessment indicated that the target efficacy was unlikely to be achieved.

The company stated in an emailed statement that clinical development of the vaccine in infants aged 3 to 7 months has been discontinued. "Preliminary data indicate that this candidate vaccine will not demonstrate high efficacy in preventing RSV disease. The company remains committed to addressing the RSV disease burden through its maternal and older adult candidate vaccines, which utilize a different technology and are both in Phase 3 trials." GSK stated that it remains confident in the potential of its viral vector technology. Currently, the company's therapeutic hepatitis B virus development program is proceeding as planned.

Several months ago, GSK initiated a late-stage clinical trial for another RSV vaccine, GSK3888550A, aimed at protecting infants against RSV infection during the first few months after birth by vaccinating pregnant women.

In addition to the termination of the pediatric RSV program, GSK also disclosed another update regarding the ICOS agonist feladilimab. In an interim analysis of a Phase 2 lung cancer study, the combination regimen of feladilimab and the chemotherapeutic agent docetaxel failed to meet the primary endpoint.

This failure was "not unexpected". In fact, in April, GSK had already decided to halt enrollment of patients with head and neck squamous cell carcinoma in the Phase 2 clinical trial of feladilimab.

Source: GSK culls phase 2 RSV vaccine in kids, as feladilimab flops again in lung cancer