Beyond tissue biopsy: a diagnostic framework to address tumor heterogeneity in lung cancer.

PURPOSE OF REVIEW: The objective of this review is to discuss the strength and limitations of tissue and liquid biopsy and functional imaging to capture spatial and temporal tumor heterogeneity either alone or as part of a diagnostic framework in non-small cell lung cancer (NSCLC). RECENT FINDINGS: NSCLC displays genetic and phenotypic heterogeneity - a detailed knowledge of which is crucial to personalize treatment. Tissue biopsy often lacks spatial and temporal resolution. Thus, NSCLC needs to be characterized by complementary diagnostic methods to resolve heterogeneity. Liquid biopsy offers detection of tumor biomarkers and for example, the classification and monitoring of EGFR mutations in NSCLC. It allows repeated sampling, and therefore, appears promising to address temporal aspects of tumor heterogeneity. Functional imaging methods and emerging image analytic tools, such as radiomics capture temporal and spatial heterogeneity. Further standardization of radiomics is required to allow introduction into clinical routine. SUMMARY: To augment the potential of precision therapy, improved diagnostic characterization of tumors is pivotal. We suggest a comprehensive diagnostic framework combining tissue and liquid biopsy and functional imaging to address the known aspects of spatial and temporal tumor heterogeneity on the example of NSCLC. We envision how this framework might be implemented in clinical practice.

The cooperating mutation or "second hit" determines the immunologic visibility toward MYC-induced murine lymphomas.

In Eµ-myc transgenic animals lymphoma formation requires additional genetic alterations, which frequently comprise loss of p53 or overexpression of BCL-2. We describe that the nature of the "second hit" affects the ability of the immune system to contain lymphoma development. Tumors with disrupted p53 signaling killed the host more rapidly than BCL-2 overexpressing ones. Relaxing immunologic control, using Tyk2(-/-) mice or by Ab-mediated depletion of CD8(+) T or natural killer (NK) cells accelerated formation of BCL-2-overexpressing lymphomas but not of those lacking p53. Most strikingly, enforced expression of BCL-2 prolonged disease latency in the absence of p53, whereas blocking p53 function in BCL-2-overexpressing tumors failed to accelerate disease. This shows that blocking apoptosis in p53-deficient cells by enforcing BCL-2 expression can mitigate disease progression increasing the "immunologic visibility." In vitro cytotoxicity assays confirmed that high expression of BCL-2 protein facilitates NK and T cell-mediated killing. Moreover, we found that high BCL-2 expression is accompanied by significantly increased levels of the NKG2D ligand MULT1, which may account for the enhanced killing. Our findings provide first evidence that the nature of the second hit affects tumor immunosurveillance in c-MYC-driven lymphomas and define a potential shortcoming of antitumor therapies targeting BCL-2.

Bone marrow infection with bacillus Calmette-Guérin (BCG) after intravesical immunotherapy.

Instillation of bacillus Calmette-Guérin (BCG) into the urine bladder is an effective treatment of superficial bladder cancer. BCG-mediated anti-tumor activity appears to be a local phenomenon in which cell-mediated immunity, involving cytotoxic T cells, lymphokine-activated killer cells and natural killer cells, is important for the elimination of malignant cells. Serious side-effects of BCG therapy are rare; nevertheless, BCG is a live, attenuated strain of Mycobacterium (M.) bovis and may exhibit invasive properties. Both local and distant or generalized infections have been reported after treatment with BCG. We describe the case of a 68-year-old man who developed bone marrow infection with BCG two years after intravesical instillation of BCG for treatment of superficial bladder cancer. He presented with intermittent fever, weight loss and pronounced pancytopenia. A bone marrow biopsy specimen showed granulomatous inflammation and BCG was cultured from the urine. Anti-mycobacterial treatment with isoniazid, rifampicin and ethambutol (pyrazinamide is inactive against M. bovis) led to full clinical recovery of the patient.