The pathologic response assessment of tumor specimens from patients undergoing systemic treatment provides an early indication of therapeutic efficacy. It predicts long-term survival as well.
Grading systems for pathologic response were first developed for chemotherapy in select tumor types. However, the immunotherapeutic agents work differently from chemotherapeutic agents. Hence, a pan-tumor standardized scoring system for immune-related pathologic response (irPR) is needed.
Researchers from Johns Hopkins University School of Medicine assessed hematoxylin and eosin-stained slides from surgical resections and on-treatment biopsies to understand the irPR. They evaluated 258 specimens from patients with 11 tumor types as part of ongoing clinical trials for anti-PD-(L)1. An additional 98 specimens from patients receiving anti-PD-(L)1 in combination with other treatments were reviewed, including those from three different tumor types.
The results of this particular study tell us that common irPR features are present in tumor types such as melanoma, non-small cell lung, head and neck squamous cell, Merkel cell, and renal cell carcinoma. These features include immune activation, cell death, tissue repair, and regression bed. What is more, these features are consistent across primary tumors, lymph nodes, and distant metastases.
In summary, the researchers found consistent irPR features across tumor types and treatment. However, prospective studies must be conducted to validate irPR criteria (irPRC) in larger datasets and associate pathologic characteristics with long-term patient outcomes.
The need for a standardized, universal scoring system for pathologic response that characterizes features typical of immunotherapy is greater than ever. This need serves as a call to action for researchers worldwide .