Hyperprogression after immunotherapy.

Introduction: Checkpoint inhibitors demonstrate very good anticancer effects, and some patients are long-time responders. As our experience to use these drugs increases, we see more and more patients having different kind of side effects which are usually not seen with chemotherapy. We have observed a subset of patients who appear to be "hyper-progressors," with a greatly accelerated rate of tumor growth and clinical deterioration compared to pretherapy, which was also recently reported by Institut Gustave Roussy.

Materials And Methods: Medical records from all patients ( = 50) prospectively treated in our hospital by anti-PD-1/PD-L1 were analyzed. The tumor growth rate (TGR) prior ("REFERENCE;" REF) and upon ("EXPERIMENTAL"; EXP) anti-PD-1/PD-L1 therapy was compared to identify patients with accelerated tumor growth. Associations between TGR and overall survival (OS) were computed.

Results: Hyperprogressive disease (HPD) was defined as a RECIST progression at the first evaluation and as a ≥2-fold increase of the TGR between the REF and the EXP periods. Of 50 evaluable patients, four patients (8%) were considered as having HPD. At progression, patients with HPD had a higher rate of new lesions. HPD was associated with a worse outcome (OS).

Conclusion: Hyperprogression was seen in 4 of 50 (8%) of patients, three of which had urothelial cancer and one malignant melanoma, treated with anti-PD-1 or anti-PD-L1 monotherapy. Patients, on immunotherapy, qualifying for hyperprogression had shorted OS. It is important to have a better understanding of hyperprogression on immunotherapy which shall be addressed in the ongoing immunotherapy studies.