Rationale: Pseudoprogression, that is, initial tumor growth followed by subsequent tumor regression, has been well described for immunomodulation therapy in melanoma patients. This phenomenon is not well defined in lung cancer. Nivolumab, an anti-PD-1 monoclonal antibody, was recently approved for nonsmall cell lung cancer (NSCLC) as a second-line therapy.
Patient concerns and diagnosis: We present a patient with squamous NSCLC, suffering from multiple bone and subcutaneous metastases.
Interventions: The patient was treated with nivolumab.
Outcomes: A subcutaneous lesion in her upper back grew substantially after the first cycle of nivolumab, and later regressed, with marked improvement in all cancer sites.
Lessons: Such pseudoprogression may serve to predict subsequent clinical response.