Pfizer aims to start clinical testing of lead compound against SARS-CoV-2 in third quarter

In an update Thursday on its efforts to combat COVID-19, Pfizer said results of initial screening assays have led it to zero in on a lead protease inhibitor with antiviral activity against SARS-CoV-2 based on preliminary data. The company stated that it will now perform preclinical testing on the compound and aims to begin a clinical trial in the third quarter, some three or more months ahead of earlier estimates. 

CEO Albert Bourla commented that Pfizer is collaborating with partners "to develop potential novel approaches to prevent and treat COVID-19," as well as "exploring potential new uses of existing medicines in [our] portfolio to help infected patients globally. We are leaving no stone unturned." 

In terms of existing drugs, Pfizer said a Phase II study is expected to start in Italy later this week evaluating the company's JAK inhibitor Xeljanz (tofacitinib), which is currently prescribed to treat rheumatoid arthritis, psoriatic arthritis and ulcerative colitis. The study will enrol 50 patients admitted to hospital due to SARS-CoV-2 symptomatic interstitial pneumonia, but not requiring mechanical ventilation. Xeljanz will be administered every day for 14 days, starting within 24 hours from admission. The primary outcome will evaluate the effect of the drug on the rate of patients who will need mechanical ventilation. 

Pfizer is also in discussions with partners about additional studies involving Xeljanz and potentially other immune modulators in its portfolio. According to the drugmaker, the research is based on the idea that "JAK inhibition could mitigate systemic and alveolar inflammation in patients with COVID-19-related pneumonia by inhibiting essential cytokine signaling" that could ultimately lead to acute respiratory distress syndrome in patients with COVID-19-related pneumonia. However, it noted that Xeljanz is not currently approved for this use and should not be given to patients with an active serious infection. 

Meanwhile, the company also provided some specifics, including financial details, about an extended partnership entered into last month with BioNTech to co-develop the mRNA-based COVID-19 vaccine candidate BNT162. Pfizer said Thursday that as part of the deal, BioNTech will receive an upfront payment of $185 million, including an equity investment of approximately $113 million, and will be eligible for future milestones of up to $563 million, for a potential total consideration of $748 million. 

The partners plan to jointly conduct clinical trials for the COVID-19 vaccine candidate initially in the US and Europe, with testing set to begin as early as the end of this month, assuming regulatory clearance. BioNTech will contribute multiple mRNA vaccine candidates as part of its BNT162 COVID-19 vaccine programme, while Pfizer will contribute its global vaccine clinical R&D, regulatory, manufacturing and distribution infrastructure and capabilities. "There is potential to supply millions of vaccine doses by the end of 2020…and then rapidly scale up to capacity to produce hundreds of millions of doses in 2021," Pfizer estimated. 

The companies will also equally share expenses tied to development, with Pfizer initially funding all of the development costs, but BioNTech eventually repaying Pfizer its 50% share of these costs during commercialisation of the vaccine. If approved, both will also co-market the vaccine worldwide, excluding in China, where BioNTech already has a deal with Fosun Pharmaceutical. 

Meanwhile, Pfizer stated it is also launching the SAFER and FASTER studies to gain insights on the interaction between S. pneumoniae and SARS-CoV-2. According to the drugmaker, the work will help determine whether COVID-19 patients are at higher risk of also developing pneumococcal pneumonia, and if having both infections leads to more severe disease and poorer outcomes. The SAFER study will enroll 100 healthcare workers at the Royal Liverpool Hospital and examine rates of SARS-CoV-2 acquisition and dynamics of pneumococcal colonisation, while the FASTER trial will recruit 400 patients from the infectious disease ward at the hospital suspected of having coronavirus. Enrollment has already begun, and data are expected over the next few months. 

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