MRI Tumor Regression Grade and Circulating Tumor DNA as Complementary Tools to Assess Response and Guide Therapy Adaptation in Rectal Cancer.

PURPOSE: Response to preoperative chemo-radiotherapy (CRT) varies. We assessed whether circulating tumor DNA (ctDNA) might be an early indicator of tumor response or progression to guide therapy adaptation in rectal cancer. EXPERIMENTAL DESIGN: A total of 243 serial plasma samples were analyzed from 47 patients with localized rectal cancer undergoing CRT. Up to three somatic variants were tracked in plasma using droplet digital PCR. RECIST and MRI tumor regression grade (mrTRG) evaluated response. Survival analyses applied Kaplan-Meier method and Cox regression. RESULTS: ctDNA detection rates were: 74% (n = 35/47) pretreatment, 21% (n = 10/47) mid CRT, 21% (n = 10/47) after completing CRT, and 13% (n = 3/23) after surgery. ctDNA status after CRT was associated with primary tumor response by mrTRG (P = 0.03). With a median follow-up of 26.4 months, metastases-free survival was shorter in patients with detectable ctDNA after completing CRT [HR 7.1; 95% confidence interval (CI), 2.4-21.5; P < 0.001], persistently detectable ctDNA pre and mid CRT (HR 3.8; 95% CI, 1.2-11.7; P = 0.02), and pre, mid, and after CRT (HR 11.5; 95% CI, 3.3-40.4; P < 0.001) compared with patients with undetectable or nonpersistent ctDNA. In patients with detectable ctDNA, a fractional abundance threshold of ≥0.07% mid CRT or ≥0.13% after completing CRT predicted for metastases with 100% sensitivity and 83.3% specificity for mid CRT and 66.7% for CRT completion. All 3 patients with detectable ctDNA post-surgery relapsed compared with none of the 20 patients with undetectable ctDNA (P = 0.001). CONCLUSIONS: ctDNA identified patients at risk of developing metastases during the neoadjuvant period and post-surgery, and could be used to tailor treatment.

Patterns of iron distribution in liver cells in beta-thalassemia studied by X-ray microanalysis.

BACKGROUND AND OBJECTIVES: beta-thalassemia is an important public health problem in the countries bordering the Mediterranean sea. One of the major consequences of this disorder, primarily (due to an ineffective erythropoiesis) or secondarily to blood transfusions (which are necessary for the patient's survival), is iron storage. Applying X-ray microanalysis we wanted to demonstrate the different sites of iron storage in subcellular compartments (mitochondria, cytosol, nucleus, rough endoplasmic reticulum and lipid droplets) and whether there were any other trace elements stored in liver cell. DESIGN AND METHODS: X-ray microanalysis was performed (at 100 kV in the STEM mode of a Hitachi H7000) on thin sections from specimens of liver biopsies from 6 patients affected by b-thalassemia, during follow-up after bone marrow transplantation. RESULTS: Spectra showed no correlation between iron peaks of lysosomes and hepatic iron concentration (HIC) or serum ferritin levels. Iron peaks were also detected in other subcellular compartments such as cisternae of rough endoplasmic reticulum, mitochondria and cytosol. No iron peaks were detected in lipid droplets and no significant iron peaks were found in the nuclei. Traces of copper were almost constantly found in lysosomes and cytosol. INTERPRETATION AND CONCLUSIONS: These results demonstrated iron storage within subcellular organelles other than lysosomes and highlighted a non-correlation between lysosomal iron peaks and HIC or serum ferritin levels. The presence of traces of copper in the lysosomes and in the cytosol may be correlated with the stronger hypothesis of links in the metabolism of the two elements (iron and copper), as ceruloplasmin is a ferroxidase copper-dependent protein. X-ray microanalysis may become a relevant tool in the localization of iron storage within hepatocytes in the evaluation of the effectiveness of bone marrow transplantation and iron chelation therapy. It also may provide some interesting information about iron metabolism in hepatocytes.