野田 弘志

BACKGROUND: Anti-epidermal growth factor receptor (EGFR) antibody is widely used for the treatment of patients with metastatic colorectal cancer. Hypomagnesemia is a comparatively frequent adverse event of this drug, which is likely overlooked because it occurs later in treatment without symptoms. Furthermore, hypomagnesemia and hypomagnesemia-induced corrected QT (QTc) prolongation may lead to loss of consciousness (LOC), the onset of which is not generally considered associated with the treatment of anti-EGFR antibody because of its rare occurrence. Here, we present a colorectal cancer patient treated with anti-EGFR antibody, who suffered LOC during treatment while severe hypomagnesemia or QTc prolongation was not observed. CASE PRESENTATION: A 69-year-old man with metastatic colon cancer was treated with cetuximab (anti-EGFR antibody) plus irinotecan as third-line chemotherapy. His serum magnesium level gradually decreased, and grade 2 hypomagnesemia (a serum magnesium level of 0.9 mg/dL) was observed at the 12th administration of cetuximab. In light of this development, intravenous supplementation of 20 mEq magnesium sulfate began with careful blood monitoring despite the lack of clinical symptoms. Electrocardiogram (ECG) showed prolonged QT or corrected QT (QTc) intervals (grade 1). His serum magnesium level remained at 0.9 mg/dL, and no hypomagnesemia symptoms were observed by the 17th administration of cetuximab. After the treatment, however, he suddenly lost consciousness without symptoms related to infusion or allergic reactions. Circulatory collapse following dermatological reactions and respiratory events were not evident. Intravenous supplementation of magnesium sulfate was administered again. He awakened 2 min after the onset of temporary LOC without any other symptoms related to hypomagnesemia, such as lethargy, tremor, tetany, and seizures. No other etiology outside of the low level of serum magnesium was confirmed in further examinations. Cetuximab was discontinued, and his serum magnesium level returned to a level within the normal range after 6 weeks. Because of tumor progression, regorafenib and TAS-102 (trifluridine tipiracil hydrochloride) were introduced sequentially for 6 months. Five months after the final treatment of TAS-102, he died of his primary disease, which reflected a survival period of 4 years and 6 months since the beginning of treatment. CONCLUSIONS: This case report reminds clinicians that LOC can be induced without severe hypomagnesemia or QTc prolongation, during anti-EGFR antibody treatment for metastatic colorectal cancer even while under carefully monitored magnesium supplementation.

As a result of recent advances in diagnostic techniques and treatment modalities, the number of patients diagnosed with multiple primary malignancies has been increasing. We report the case of a 79-year-old male with multiple primary malignancies of three histological types in six different organs: Stomach, prostate, colon, urinary bladder, facial skin and pancreas, in chronological order. The first malignancy was upper gastric cancer diagnosed in 1998. The second and third malignancies were prostate cancer and ascending colon cancer, which were diagnosed in 2010. The fourth malignancy was bladder cancer diagnosed in 2011. The fifth and sixth malignancies were squamous cell skin cancer of the right cheek and intraductal papillary mucinous carcinoma (IPMC), respectively, diagnosed in 2014. The gastric cancer, colon cancer, bladder cancer, skin cancer and IPMC were surgically resected. The prostate cancer was treated by anti-androgen therapy. The patient died of local recurrence of IPMC in August 2016. Although multiple primary malignancies are not uncommon, diagnosis of six primary malignancies in a single patient, as reported in the present study, is extremely rare. It is important to understand the characteristics of multiple primary malignancies in order to administer suitable treatment and determine relevant follow-up plans for patients with cancer.

BACKGROUND: Liquid biopsies enable the detection of circulating tumor DNA (ctDNA). However, the clinical significance of KRAS-mutated ctDNA for pancreatic cancer has been inconsistent with respect to its prognostic and predictive potential. METHODS AND FINDINGS: A total of 422 blood samples were collected from 78 patients undergoing treatments for localized and metastatic pancreatic ductal adenocarcinoma. KRAS mutation in tissues and KRAS ctDNA levels in plasma were determined by RASKET and droplet digital polymerase chain reaction. Longitudinal monitoring of KRAS ctDNA was performed to assess its significance for predicting recurrence and prognosis and for evaluating therapeutic responses to chemotherapy compared with carbohydrate antigen 19-9 (CA19-9). In 67 tumor tissues, discrepancies in point mutations of KRAS were rarely observed among individual patients, implying that one targeted point mutation of KRAS can be determined in tumor tissues prior to longitudinal blood monitoring. One-time blood assessment of KRAS-mutated ctDNA before surgery or chemotherapy was not clearly associated with recurrence and prognosis. Sequential blood monitoring was performed in 39 patients who underwent surgery for potentially resectable tumors. Increased CA19-9 levels were significantly associated with recurrence, but not prognosis (P<0.001, P = 1.0, respectively), whereas emergence of KRAS ctDNA was significantly associated with prognosis (P<0.001) regardless of recurrence. Furthermore, in 39 patients who did not undergo surgery, detection of KRAS ctDNA was a predictive factor for prognosis (P = 0.005). Multivariate analysis revealed that detection of KRAS ctDNA was the only independent prognostic factor regardless of tumor resection (hazard ratios = 54.5 for patients who underwent surgery and 10.1 for patients who did not undergo surgery; P<0.001 for both). Patients without emergence of KRAS ctDNA within 1 year after surgery showed significantly better prognosis irrespective of recurrence (P<0.001). No detection or disappearance of KRAS ctDNA within 6 months of treatment was significantly correlated with therapeutic responses to first-line chemotherapy (P<0.001). Changes in KRAS status provided critical information for the prediction of therapeutic responses. CONCLUSIONS: Our study showed for the first time that detection of KRAS ctDNA levels within a short period enables the prediction of prognosis and therapeutic responses in patients with pancreatic cancer.

KRAS mutated circulating tumor DNA (MctDNA) can be monitored in the blood of patients with metastatic colorectal cancer (mCRC), but dynamic changes have not been determined. Four hundred and fifty-seven plasma samples were collected prospectively from 85 mCRC patients who underwent chemotherapy. MctDNA in plasma was detected by droplet digital PCR, and the percentage of MctDNA in total circulating cell-free DNA was calculated. KRAS assessment in tumor tissues showed 29 patients with the mutant-type (MT) and 56 patients with the wild-type (WT). Twenty-three of 29 MT patients (79.3%) and 28 of 56 WT patients (50.0%) showed MctDNA. Emergence of MctDNA was recognized during treatments with various drugs. Regardless of KRAS status in tumor tissues, patients with MctDNA in blood showed poor progression-free survival with first-line treatment. Median percentage of MctDNA accounted for 10.10% in MT patients and 0.22% in WT patients. These differences between MT and WT likely affected patterns of changes in MctDNA. KRAS monitoring identified dynamic changes in MctDNA, such as continuous, intermittent, and transient changes (quick elevation and disappearance). Emergence of MctDNA involved drug resistance, except for transient changes, which were seen in WT patients and likely corresponded with the drug response. Transient changes could be involved in recovery of sensitivity to anti-EGFR antibody in WT patients. Monitoring MctDNA during various treatments showed dynamic changes in KRAS status and could provide useful information for determining treatments for patients with mCRC.

The impairment of the stability of the chromosomal structure facilitates the abnormal segregation of chromosomes, thus increasing the risk of carcinogenesis. Chromosomal stability during segregation is managed by appropriate methylation at the centromere of chromosomes. Insufficient methylation, or hypomethylation, results in chromosomal instability. The centromere consists of satellite alpha repetitive sequences, which are ideal targets for DNA hypomethylation, resulting in the overexpression of satellite alpha transcript (SAT). The overexpression of SAT has been reported to induce the abnormal segregation of chromosomes. In this study, we verified the oncogenic pathway via chromosomal instability involving DNA hypomethylation and the overexpression of SAT. For this purpose, we constructed lentiviral vectors expressing SAT and control viruses and then infected human mammary epithelial cells with these vectors. The copy number alterations and segregation errors of chromosomes were evaluated by microarray-based comparative genomic hybridization (array CGH) and immunocytochemistry, respectively. The levels of hypomethylation of satellite alpha sequences were determined by MethyLight polymerase chain reaction. Clinical specimens from 45 patients with breast cancer were recruited to verify the data in vitro. The results of immunocytochemistry revealed that the incidence of segregation errors was significantly higher in the cells overexpressing SAT than in the controls. An array CGH identified the specific chromosomes of 8q and 20q as frequent sites of copy number alterations in cells with SAT overexpression, although no such sites were noted in the controls, which was consistent with the data from clinical specimens. A regression analysis revealed that the expression of SAT was significantly associated with the levels of hypomethylation of satellite alpha sequences. On the whole, the overexpression of SAT led to chromosomal instability via segregation errors at specific chromosomes in connection with DNA hypomethylation, which was also recognized in clinical specimens of patients with breast cancer. Thus, this oncogenic pathway may be involved in the development of breast cancer.

BACKGROUND: To evaluate the clinical significance of a CT-based evaluation of abdominal aortic calcification (AAC) in the postoperative outcomes after pancreaticoduodenectomy (PD) in elderly patients. METHODS: Patients 70 years of age and older who were randomly assigned to Group A were compared with those younger than 70 who were assigned to Group B in terms of preoperative and intraoperative variables and postoperative outcomes. We compared the patients with clinically relevant postoperative pancreatic fistula (CR-POPF) (Group C) to those without CR-POPF (Group D), and especially Group A. We also compared the patients with CR-POPF (Group E) to those without CR-POPF (Group E) to clarify the risk factors for POPF, in each of the analyses. The AAC score was determined using the methods of Agatston et al. RESULTS: Group A more often had frequent atherosclerosis-related comorbidities (62.2%), low serum albumin (55.9%), and a high AAC score (66.1%). There were no significant differences in the postoperative variables. The comparisons between Groups C and D identified four independent risk factors for CR-POPF: BMI ≥ 25 (OR 8.54, 95% CI 3.15-23.1), male gender (OR 3.17, 95% CI 1.28-7.85), soft pancreatic parenchyma (OR 3.43, 95% CI 1.34-8.81), and the absence of MPD dilatation (OR 5.70, 95% CI 2.13-15.3). Comparisons between Groups E and F identified two independent risk factors for CR-POPF: BMI ≥ 25 (OR 29.4, 95% CI 5.77-150) and a high ACC score (OR 10.8, 95% CI 2.08-56.6). CONCLUSIONS: We demonstrated, for the first time, that a high AAC score is a risk factor of CR-POPF in elderly patients who underwent PD.

Regorafenib has shown survival benefits in metastatic colorectal cancer patients who were exacerbated after all standard therapies. Some patients, however, exhibit severe adverse events (AEs) resulting in treatment discontinuation. Therefore, the selection of patients likely to benefit from regorafenib is crucial. Twenty patients were treated with regorafenib for metastatic colorectal cancer; 122 plasma samples were taken from 16 of these patients for monitoring of circulating tumor DNA (ctDNA) in the blood. The treatment response, AEs, overall survival (OS), progression-free survival (PFS) and tumor morphologic changes on CT images were evaluated. KRAS mutant ctDNA was determined using digital PCR. Median PFS and OS were 2.5 and 5.9 months, respectively. Treatment was discontinued because of disease progression (PD) in 10 patients, and AEs in another 10 patients. AEs included hyperbilirubinemia, severe fatigue and skin rash. Hyperbilirubinemia was seen in two patients with multiple bilateral liver metastases, and severe fatigue in another 2 patients with poor performance status (PS). These severe AEs resulted in treatment discontinuation. Ten patients had a median PFS of 2.1 months with AE related discontinuation; PD occurred at 3.5 months (p=0.00334). Four patients exhibited a morphologic response, achieving better PFS times of 3.5, 5.3, 5.6 and 14.2 months. Emergence of the KRAS mutation in ctDNA was observed during anti-EGFR antibody treatment in 3 patients among 11 with KRAS wild-type tumors; it was detectable in the blood prior to radiographic detection of PD. Moreover, the KRAS mutation declined in two patients during regorafenib monotherapy. These patients were re-challenged with anti-EGFR antibody. Patients with extensive multiple liver metastases or poor PS are unlikely to benefit from regorafenib. Patients with a morphologic response will probably benefit from regorafenib with adequate management of other AEs. KRAS monitoring in ctDNA could be useful regarding treatment response and in determining treatment strategy.