NTRK fusion protein expression is absent in a large cohort of diffuse large B-cell lymphoma

Background

Even though two NTRK-targeting drugs are available for the treatment of irresectable, metastatic, or progressive NTRK-positive solid tumors, less is known about the role of NTRK fusions in lymphoma. For this reason, we aimed to investigate if NTRK fusion proteins are expressed in diffuse large B-cell lymphoma (DLBCL) by systemic immunohistochemistry (IHC) screening and additional FISH analysis in a large cohort of DLBCL samples according to the ESMO Translational Research and Precision Medicine Working Group recommendations for the detection of NTRK fusions in daily practice and clinical research.

Methods

A tissue microarray of 92 patients with the diagnosis of DLBCL at the University Hospital Hamburg between 2020 and 2022 was built. The clinical data were taken from patient records. Immunohistochemistry for Pan-NTRK fusion protein was performed and positive staining was defined as any viable staining. For FISH analysis only results with quality 2 and 3 were evaluated.

Results

NTRK immunostaining was absent in all analyzable cases. No break apart was detectable by FISH.

Conclusion

Our negative result is consistent with the very sparse data existing on NTRK gene fusions in hematologic neoplasms. To date, only a few cases of hematological malignancies have been described in which NTRK-targeting drugs may provide a potential therapeutic agent. Even though NTRK fusion protein expression was not detectable in our sample cohort, performing systemic screenings for NTRK fusions are necessary to define further the role of NTRK fusions not only in DLBCL but in a multitude of lymphoma entities as long as the lack of reliable data exists.

The prognostic impact of B7-H3 and B7-H4 in head and neck squamous cell carcinoma

PURPOSE

Immune checkpoint inhibition is a therapeutic option in many cancer entities. In head and neck squamous cell carcinoma (HNSCC) targeting of the PD-1/PD-L1 (B7-H1) axis is approved in recurrent/metastatic disease and is being explored in the curative setting. Here, we evaluated two related members of the B7 family, B7-H3 & B7-H4, for their prognostic impact under standard treatment.

METHODS

A tissue microarray (TMA) of a single center HNSCC cohort was stained for B7-H3 and B7-H4. Staining intensity and the number of tumor cells stained were assessed, and the expression was scored according to an established algorithm. Staining scores were correlated with clinicopathological parameters and associated with patient survival. mRNA levels of both proteins were associated with patient outcome using the TCGA dataset.

RESULTS

mRNA levels of B7-H3 and B7-H4 were not significantly associated with patient survival. TMA analysis revealed interpretable protein staining in 408 samples. Strong staining was the most frequent category for B7-H3 and no staining for B7-H4. In patients with p16-negative oropharyngeal SCC (OPSCC) and in a pooled cohort consisting of p16-negative OPSCC, laryngeal, hypopharyngeal and oral cavity SCC, strong B7-H3 expression was associated with better overall survival. For the latter cohort, this was in part due to reduced lymph node involvement. B7-H3 expression in p16-positive OPSCC and B7-H4 expression were not associated with outcome.

CONCLUSION

Despite a possible role in tumor immune escape, B7-H3 was associated with favorable prognosis in HPV-negative HNSCC in our cohort. The underlying mechanisms and a potential impact for B7-H3 targeting remain to be elucidated.

Kinomic comparison of snap frozen and ex vivo-cultured head and neck tumors

OBJECTIVES

The use of primary tumor tissue in experimental and pre-clinical cancer research is becoming increasingly important. Especially the use of tissue slice cultures of tumor specimen, so called ex vivo cultures or tumor explants, promises functional analysis under approximate physiological conditions. This includes screening and testing of targeted therapeutics directed against deregulated protein kinases. However, it is unclear if ex vivo cultures indeed represent the in situ situation especially with respect to very sensitive and transient molecular processes such as kinase dependent signaling. We now asked here, if and to what extent ex vivo culturing affects kinase activity.

MATERIALS AND METHODS

We analyzed the activity of protein tyrosine kinases (PTK) using functional kinome profiling of either snap frozen or ex vivo-cultured tumor tissue samples of head and neck cancer patients.

RESULTS

Although we observed a quantitative decline in overall kinase activity after 24 h or 48 h of ex vivo cultivation, we most importantly noticed that the signaling characteristics were conserved in most samples; approximately two thirds of all ex vivo-cultured samples displayed a signaling pattern which was qualitatively comparable to the parental tumor. We could also demonstrate kinase inhibition by treatment of ex vivo slice cultures with the multi-kinase inhibitor staurosporine, although higher concentrations were needed compared to cell cultures.

CONCLUSION

We here demonstrate that the tyrosine kinase dependent signaling is conserved under exvivo culturing conditions in the majority of samples, which highlights the power of this method in experimental and pre-clinical cancer research.

Diagnostic and prognostic impact of cytokeratin 19 expression analysis in human tumors: a tissue microarray study of 13,172 tumors

To evaluate cytokeratin 19 (CK19) expression in normal and cancerous tissues, 15,977 samples from 122 tumor types and 608 samples of 76 normal tissue types were analyzed by immunohistochemistry (IHC). In normal tissues, CK19 expression occurred in epithelial cells of most glandular organs but was strictly limited to the basal cell layer of nonkeratinizing squamous epithelium and absent in the skin. CK19 expression in ≥90% of cases was seen in 34% of the tumor entities including the adenocarcinomas of the pancreas (99.4%), colorectum (99.8%), esophagus (98.7%), and stomach (97.7%), as well as breast cancer (90.0%-100%), high-grade serous (99.1%) or endometrioid (97.8%) ovarian cancer, and urothelial carcinoma (92.6%-100%). A low CK19 positivity rate (0.1-10%) was seen in 5 of 122 tumor entities including hepatocellular carcinoma and seminoma. A comparison of tumor versus normal tissue findings demonstrated that upregulation and downregulation of CK19 can occur in cancer and that both alterations can be linked to unfavorable phenotypes. CK19 downregulation was linked to high grade (p = 0.0017) and loss of estrogen receptor- and progesterone receptor-expression (p < 0.0001 each) in invasive breast carcinoma of no special type. CK19 upregulation was linked to nodal metastases in neuroendocrine tumors and papillary thyroid carcinomas (p < 0.05 each) and to poor grade in clear cell renal cell carcinoma (p < 0.05). CK19 upregulation was particularly common in squamous cell carcinomas. We concluded that CK19 IHC might separate primary liver cell carcinoma from liver metastases, seminoma from other testicular tumors, and helps in the detection of early neoplastic transformation in squamous epithelium.

Analyzing tyrosine kinase activity in head and neck cancer by functional kinomics: Identification of hyperactivated Src family kinases as prognostic markers and potential targets

Signal transduction via protein kinases is of central importance in cancer biology and treatment. However, the clinical success of kinase inhibitors is often hampered by a lack of robust predictive biomarkers, which is also caused by the discrepancy between kinase expression and activity. Therefore, there is a need for functional tests to identify aberrantly activated kinases in individual patients. Here we present a systematic analysis of the tyrosine kinases in head and neck cancer using such a test-functional kinome profiling. We detected increased tyrosine kinase activity in tumors compared with their corresponding normal tissue. Moreover, we identified members of the family of Src kinases (Src family kinases [SFK]) to be aberrantly activated in the majority of the tumors, which was confirmed by additional methods. We could also show that SFK hyperphosphorylation is associated with poor prognosis, while inhibition of SFK impaired cell proliferation, especially in cells with hyperactive SFK. In summary, functional kinome profiling identified SFK to be frequently hyperactivated in head and neck squamous cell carcinoma. SFK may therefore be potential therapeutic targets. These results furthermore demonstrate how functional tests help to increase our understanding of cancer biology and support the expansion of precision oncology.