The assessment of tumor-infiltrating lymphocytes in invasive apocrine carcinoma of the breast in relation to the HER2 status.

In the current study, we assessed the prevalence and molecular features of HER2-low phenotype in the apocrine carcinomas of the breast (ApoCa) and its relationship with tumor-infiltrating lymphocytes (TILs). A cohort of 64 well-characterized therapy-naïve ApoCa was used. The TIL distribution was assessed using the hematoxylin and eosin whole slide/scanned images following the international TILs working group recommendations. Next-generation sequencing (NGS) was performed in a subset of HER2-low ApoCa. All patients were women, with a mean age of 62 years. Forty-three carcinomas were pure apocrine carcinoma (PAC; ER-/AR+), and the remaining 21 were classified as apocrine-like carcinomas (ALCs; ER+/-, AR+/-). HER2/neu was positive (score 3+ by IHC and/or amplified by FISH) in 20/43 (47%) PAC and 4/21 (19%) ALC. The prevalence of HER2-low expression (scores 1+ or 2+ without HER2 amplification) in ApoCa was 39% without significant differences between PAC and ALC (P = 0.14); however, the HER2-low phenotype was more prevalent in triple-negative PAC than in ALC (P < 0.001). Levels of TILs were low (≤10%) in 74% of ApoCa (median 5%, range 0%-50%). TIL levels were significantly higher in ALC than in PAC (P = 0.02). HER2 status had no impact on TIL distribution (P = 0.45). The genomic profile of HER2-low ApoCa was similar to other subtypes of ApoCa. ApoCa has predominantly low TIL, particularly PAC. The prevalence of the HER2-low phenotype in ApoCa is high, which should have therapeutic and clinical implications given the recently approved therapies with antibody-drug conjugates (ADCs) for HER2-low breast cancers.

Composition of the immune microenvironment differs between carcinomas metastatic to the lungs and primary lung carcinomas.

Lungs are among the most common sites for development of both primary and metastatic carcinomas. Tumor cells expression (TC) of PD-L1 is an important predictor of the of response to immune check-point inhibition in NSCLC, while the composition of the immune cells (IC) in the tumor microenvironment including PD-L1+ cells is believed to predict responses in tumors of some other primary sites. Total mutational load (TML) and microsatellite instability (MSI) also play a role in response to the immune checkpoint blockade. We investigated immune microenvironment characteristics (PD-1, PD-L1, CD8) of 257 lung biopsies including 81 primary (NSCLC) and 176 metastatic tumors to the lungs. TML and MSI were calculated from massively parallel sequencing (592-gene panel). TC expression of PD-L1 was more common in NSCLC than in metastatic carcinomas (28% vs. 10%, p=0.009), while PD-L1-positive IC were present at relevant percentages (1-5%) exclusively in metastatic carcinomas (31% IC positive vs. 0%, p<0.001). Metastatic carcinomas carried significantly lower TML in comparison with the NSCLCs (6.6 mutations on average vs. 10, p=0.01). All primary NSCLC were microsatellite stable, and only 2 metastatic carcinomas exhibited MSI-H status. The number of PD-1+ and CD8+ tumor infiltrating lymphocytes did not differ significantly between the primary and metastatic carcinomas. Our study revealed significant differences in tumor immune microenvironment (PD-L1 in IC and TC), and its relationship to TML between NSCLC and metastatic cancers. These differences could determine the choice of a predictive biomarker test and subsequently effect(s) of the immune therapy treatments in various advanced cancers.

Programmed cell death 1 (PD-1) and its ligand (PD-L1) in common cancers and their correlation with molecular cancer type.

Cancer cells expressing PD-1 ligands (PD-L1/PD-L2) inhibit immune-modulatory T-cell activation facilitating disease progression. Preliminary clinical trials exploring interruption of PD-1/PD-L1 signaling showed benefit in several cancer types. We analyzed the distribution of PD-1-positive tumor-infiltrating lymphocytes (TIL) and cancer cells' expression of PD-L1 in a molecularly profiled cohort of 437 malignancies (380 carcinomas, 33 sarcomas, and 24 melanomas). We showed that the presence of PD-1(+) TILs significantly varied among cancer types (from 0% in extraskeletal myxoid chondrosarcomas to 93% in ovarian cancer), and was generally associated with the increased number of mutations in tumor cells (P = 0.029). Cancer cell expression of PD-L1 varied from absent (in Merkel cell carcinomas) to 100% (in chondro- and liposarcomas), but showed the inverse association with the number of detected mutations (P = 0.004). Both PD-1 and PD-L1 expression were significantly higher in triple-negative breast cancers (TNBC) than in non-TNBC (P < 0.001 and 0.017, respectively). Similarly, MSI-H colon cancers had higher PD-1 and PD-L1 expression than the microsatellite stable tumors (P = 0.002 and 0.02, respectively). TP53-mutated breast cancers had significantly higher PD-1 positivity than those harboring other driver mutations (e.g., PIK3CA; P = 0.002). In non-small cell lung cancer, PD-1/PD-L1 coexpression was identified in 8 cases (19%), which lacked any other targetable alterations (e.g., EGFR, ALK, or ROS1). Our study demonstrated the utility of exploring the expression of two potentially targetable immune checkpoint proteins (PD-1/PD-L1) in a substantial proportion of solid tumors, including some aggressive subtypes that lack other targeted treatment modalities.