Hyperprogression: A Unique Phenomenon of Progression of Existing Tumor Secondary to Immunotherapy

Immunotherapy is a relatively new approach for cancer treatment that has demonstrated prolonged survival by enhancing the body’s immunologic response among advanced cancer patients. Although the benefits of immunotherapy have been well documented, potentially detrimental consequences such as pseudoprogression and hyperprogression have been identified. Hyperprogression is a tumor response in which the existing underlying tumor grows rapidly after initiating treatment with an immune checkpoint inhibitor. This report presents a case of hyperprogression of non-small-cell lung cancer in a 71-year-old male who was initially treated with four cycles of chemotherapy (carboplatin and pemetrexed) and later started on maintenance therapy with pembrolizumab and chemotherapy. Two weeks after receiving the first cycle of immunotherapy, he presented with a complaint of shortness of breath. On repeat computed tomography of the chest, he was found to have a two-fold increase in the size of the preexisting tumor with new large multiloculated right pleural effusion and abdominal ascites.