Ofatumumab-associated acute pneumonitis: Not new but still the first case

Ofatumumab is an anti-CD20 humanized monoclonal antibody utilized in the treatment of several clinical conditions resistant to other treatments. In spite there was a general expectation that ofatumumab was less toxic compared to rituximab, side effects have been reported that resemble those of its anti-CD20 chimeric precursor. Here, we describe the first case of Ofatumumab associate lung injury occurring in a 14-year-old boy affected by nephrotic syndrome dependent to prednisone plus cyclosporine A who had been treated with the dose of drug utilized in nephrotic syndrome (1500 mg/173 m²). The patient developed the full blown picture of rituximab associated lung injury (RALI) after 45 days from ofatumumab infusion at the end of the steroid tapering: severe exertional dyspnea, mild fever and cyanosis, with CT scan showing diffuse ground glass areas in both lungs and D_LCO (diffusing capacity of transfer factor of the lung for carbon monoxide) test suggestive for reduction of CO diffusion. Clinical outcome was good with rapid improvement and normalization of all parameters without any specific therapy. After 60 days, chest CT and CO diffusion tests were normal. In conclusion, we describe here the first case of acute pneumonitis associated with ofatumumab that presents the same clinical, laboratory, and radiology features of the lung injury reported for rituximab. Like RALI occurring in patients treated for nephrotic syndrome, this case had a mild clinical expression and recovered in a few months.