Assessment of the immune response to tumors is growing in importance as the prognostic implications of this response are increasingly recognized, and as immunotherapies are evaluated and implemented in different tumor types. However, many different approaches can be used to assess and describe the immune response, which limits efforts at implementation as a routine clinical biomarker. In part 1 of this review, we have proposed a standardized methodology to assess tumor infiltrating lymphocytes (TILs) in solid tumors, based on the International Immuno-Oncology Biomarkers Working Group guidelines for invasive breast carcinoma. In part 2 of this review, we discuss the available evidence for the prognostic and predictive value of TILs in common solid tumors, including carcinomas of the lung, gastrointestinal tract, genitourinary system, gynecological system, and head and neck, as well as primary brain tumors, mesothelioma and melanoma. The particularities and different emphases in TIL assessment in different tumor types are discussed. The standardized methodology we propose can be adapted to different tumor types and may be used as a standard against which other approaches can be compared. Standardization of TIL assessment will help clinicians, researchers and pathologists to conclusively evaluate the utility of this simple biomarker in the current era of immunotherapy.

Purpose Considerable molecular heterogeneity exists among human epidermal growth factor receptor 2 (HER2) –positive breast cancer regarding gene expression and mutation profiling. Evidence from preclinical, clinical neoadjuvant, and metastatic clinical trials suggested that PIK3CA mutational status and PAM50 intrinsic subtype of a tumor were markers of response to anti-HER2 therapies. We evaluated the predictive value of these two biomarkers in the adjuvant setting using archived tumor blocks from National Surgical Adjuvant Breast and Bowel Project (NSABP) trial B-31. Patients and Methods Expression data for 49 genes using the nCounter platform were used to generate PAM50 intrinsic subtypes for 1,578 archived tumor blocks from patients in the B-31 trial. Six PIK3CA hotspot mutations were examined by mass spectrometry of the primer extension products in a randomly selected subset (n = 671). We examined the heterogeneity of trastuzumab treatment effect across different subsets defined by each marker using Cox regression and disease-free survival as the end point. Results Seven hundred forty-one (47.0%) of 1,578 tumors were classified as HER2-enriched (HER2E) subtype, and 166 (24.7%) of 671 tumors had PIK3CA mutations. Hazard ratios (HRs) for trastuzumab in HER2E and other subtypes were 0.44 (95% CI, 0.34 to 0.58; P < .001) and 0.47 (95% CI, 0.35 to 0.62; P < .001), respectively (interaction P = .67). HRs for trastuzumab in PIK3CA wild-type and mutated tumors were 0.51 (95% CI, 0.37 to 0.71; P < .001) and 0.44 (95% CI, 0.24 to 0.82; P = .009), respectively (interaction P = .64). Conclusion Unlike results seen in the metastatic and neoadjuvant clinical trials, PIK3CA and PAM50 intrinsic subtypes were not predictive biomarkers for adjuvant trastuzumab in NSABP B-31. These data suggest that results from the metastatic and neoadjuvant setting may not be always applicable to the adjuvant setting.

We developed a gene expression-based predictive model for degree of benefit from trastuzumab and demonstrated that HER2-negative tumors belong to the moderate benefit group, thus providing justification for testing trastuzumab in HER2-negative patients (NSABP B-47).