Isocitrate Dehydrogenase IDH1 and IDH2 Mutations in Human Cancer: Prognostic Implications for Gliomas

Background: There are isolated reports of mutations in genes for isocitrate dehydrogenases (IDH1 and IDH2), but few have been examined in a large number of different malignancies. We aimed to analyze mutational prevalence of these genes in a large series of cancers and determine their significance in most mutated phenotype.

Methods: We analyzed the frequencies of IDH1 and IDH2 mutations in 14,726 malignancies of 37 cancers. Furthermore, we examined these mutations in the most frequent cancer (gliomas, 923 cases) from a single cohort, and determined their clinical significance.

Results:IDH1 mutations were present in 3% (473/14,726) of cancers. The highest frequencies were in oligodendrogliomas (91/102, 89%), anaplastic oligodendrogliomas (40/46, 87%), and diffuse astrocytomas (89/116, 77%). IDH2 mutation was detected in <1% (83/14,726) of cancers, but were present in 13% (6/46) of anaplastic oligodendrogliomas, 9% (9/102) of oligodendrogliomas, and in 5% (2/39) of cutaneous squamous cell carcinomas. Further analyses of 923 gliomas revealed 34 and 1% of IDH1 and IDH2 mutations, respectively. In up to 342 months of follow-up, IDH1 and IDH2 mutations were significantly linked with better overall (OS) (both p = 0.01) and progression-free survival (PFS) (p = 0.01; p = 0.004), respectively.

Conclusion:IDH1 and IDH2 are often mutated in a tissue-specific manner, most commonly in gliomas. Mutation in both genes is linked to OS and PFS. Our findings suggest that these genes are promising therapeutic targets and strong prognostic biomarkers in gliomas.

Cannabinoid 2 receptor induction by IL-12 and its potential as a therapeutic target for the treatment of anaplastic thyroid carcinoma

Anaplastic thyroid carcinoma is the most aggressive type of thyroid malignancies. Previously, we demonstrated that tumorigenicity of anaplastic thyroid carcinoma cell line ARO was significantly reduced following interleukin (IL)-12 gene transfer. We suspected that tumor target structure in ARO/IL-12 cells might be changed and such a change may make them more susceptible to be killed through mechanisms apart from natural killer-dependent pathway. To identify genes involved, we examined gene expression profile of ARO and ARO/IL-12 by microarray analysis of 3757 genes. The most highly expressed gene was cannabinoid receptor 2 (CB2), which was expressed eightfold higher in ARO/IL-12 cells than ARO cells. CB2 agonist JWH133 and mixed CB1/CB2 agonist WIN-55,212-2 could induce significantly higher rate of apoptosis in ARO/IL-12 than ARO cells. Similar results were obtained when ARO cells were transfected with CB2 transgene (ARO/CB2). A considerable regression of thyroid tumors generated by inoculation of ARO/CB2 cells was observed in nude mice following local administration of JWH133. We also demonstrated significant increase in the induction of apoptosis in ARO/IL12 and ARO/CB2 cells following incubation with 15 nM paclitaxel, indicating that tumor cells were sensitized to chemotherapy. These data suggest that CB2 overexpression may contribute to the regression of human anaplastic thyroid tumor in nude mice following IL-12 gene transfer. Given that cannabinoids have shown antitumor effects in many types of cancer models, CB2 may be a viable therapeutic target for the treatment of anaplastic thyroid carcinoma.

Association of mitochondrial DNA transversion mutations with familial medullary thyroid carcinoma/multiple endocrine neoplasia type 2 syndrome

Medullary thyroid carcinoma (MTC) is a malignant tumour of the calcitonin-secreting parafollicular C cells of the thyroid, and occurs sporadically or as a component of the multiple endocrine neoplasia (MEN) type 2/familial medullary thyroid carcinoma (FMTC) syndromes. In the present study, we investigated the frequency of mtDNA mutations in 26 MTC tumour specimens (13 sporadic and 13 familial MTC) and their matched normal tissues by sequencing the entire coding regions of mitochondrial genome. Nonsynonymous mutations were detected in 20 MTC samples (76.9%): nine out of 13 sporadic MTC (69.2%) and 11 out of 13 (84.6%) familial MTC/MEN2. Both transition and transversion types of mutations were found in the samples. Interestingly, 76.2% (16/21) of transversion mutations were found in FMTC/MEN2 patients, whereas 66.7% (12/18) of transition mutations were in sporadic MTC. Synonymous mutations were found in 12 MTC samples. In total, we identified 27 transversion mutations (21 nonsynonymous and six synonymous) in MTC. Of them, 22 (81.5%) were from FMTC/MEN2, and five (18.5%) were from sporadic MTC. The association of transversion mutation with familial MTC/MEN2 was statistically significant (P = 0.0015, binomial test). Majority of the mutations were involved in the genes located in the complex I of the mitochondrial genome, and were often resulting in a change of a moderately or highly conserved amino acid of their corresponding protein. Mitochondrial respiratory function was also compromised in a TT cell line, which carries mtDNA mutation at nt 4917 and 11,720, and in peripheral lymphocytes of MTC patients with mtDNA mutations. These data suggest that mtDNA mutation may be involved in MTC tumourigenesis and progression. Given that mtDNA mutation spectra are different between sporadic and familial MTC, different mechanisms of oxidative DNA damage may occur in the disease process.

Long-term course and predictive factors of elevated serum thyroglobulin and negative diagnostic radioiodine whole body scan in differentiated thyroid cancer

Following the initial management, some patients with differentiated thyroid cancer (DTC) develop a state of high thyroglobulin (Tg) and negative diagnostic radioactive iodine (RAI) whole body scan (DxWBS). The predisposing factors and outcome of this condition are unclear. In this study, our objectives were to determine the predictive factors for the development of high Tg and negative DxWBS (Tg+/scan-) and to study the long-term course of the disease in patients with this condition.

METHODS

We, retrospectively, reviewed the medical records of a cohort of 105 non-selected DTC patients (26 males and 79 females; median age 37.7 yr, range 7-72). None of these patients had positive Tg antibodies or distant metastases. All Tg levels were obtained off thyroid hormone therapy. At the first follow-up visit after RAI ablation (13 +/- 7.6 months), patients were classified into those with low Tg (<2 ng/ml off L-T4) and negative DxWBS (control group) and those with high Tg ( > or = 22 ng/ ml off L-T4) and negative DxWBS (Tg+/scan- group). Using univariate and multivariate logistic regression analyses, we evaluated a number of parameters (see results) for their association with the development of Tg+/scan-. In addition, the long-term course of the disease in Tg+/scan- group was analyzed.

RESULTS

In univariate analysis, the following factors were found to be significantly associated with Tg+/scan-: perithyroidal tumor extension (p=0.025), soft tissue invasion (p=0.001), cervical lymph node metastases (p=0.014) and Tg level before RAI ablation (p=0.015). In multivariate analysis, only soft tissue invasion remained significantly associated with Tg+/scan- [p 0.001, odds ratio, 15.6 (95% Cl, 2.96-82.06)]. Age, sex, duration of goiter before surgery, pressure symptoms, tumor size, tumor multifocality, lymph nodedissection at initial surgery, tumor-node-metastasis (TNM) stage, and RAI ablative dose were not associated with Tg+/ scan-. In 53 patients with Tg+/scan-, 42 cases were followed without any therapeutic intervention; over a median follow-up of 71.6 months (range, 13-144.7), 31 cases had a spontaneous remission and 11 cases continued to have a persistent disease (Tg > or = 2 ng/ml, negative DxWBS, and no palpable disease or distant metastases); Tg declined from 9.32 +/- 9.91 ng/ml at first visit after RAI ablation to 1.59 +/- 5.39 ng/ml at last visit (p<0.0001). In the other 11 cases of Tg+/scan- group, one or more therapeutic interventions (RAI, surgery, or external radiotherapy) were undertaken. Over a median follow-up of 98.4 months (range, 6-147), Tg decreased from 110.2 +/- 147.5 to 23.5 +/- 41.2 ng/ml (p 0.026); 4 cases achieved remission, 5 cases continued to have persistent disease, and 2 cases had progression of their disease, which led to their death.

CONCLUSION

Soft tissue invasion on original surgery strongly predicts the development of Tg+/scan- in DTC patients. The long-term course of the disease is mostly favorable especially when the Tg level is only modestly elevated.

Impact of cervical lymph node dissection on serum TG and the course of disease in TG-positive, radioactive iodine whole body scan-negative recurrent/persistent papillary thyroid cancer

In the management of papillary thyroid cancer (PTC), surgery is indicated for locoregional recurrent/persistent disease. In this study, we examined the effect of such surgery on serum TG and the course of the disease in 21 patients with PTC (mean age 38.5 yr), who after the initial surgery and radioactive iodine (RAI) ablation developed high TG (>10 ng/ml) and negative 123I whole body scan (DxWBS). All patients had neck persistent/recurrent PTC that was confirmed by ultrasound-guided fine needle aspiration. Prior to neck re-exploration, radiological studies (chest X-rays, CT scan of the chest, and fluoro-18-deoxyglucose positron emission tomography [FDG-PET]) showed no evidence of distant metastases. TG autoantibodies were negative in 19 patients. Second surgery consisted of unilateral (13 patients) or bilateral (8 patients) modified neck dissection. The mean+/-SE TG prior to neck re-exploration was 184.8+/-79.0 ng/ml and declined after surgery to 127.5+/-59.0 ng/ml (p=0.25). The corresponding TSH values were 150.6+/-23.0 and 143.4+/-20.0 mU/l, respectively (p=0.34). After a mean follow-up of 20.7+/-3 months, TG increased to 168+/-68.0 ng/ml. This increase, however, was NS (p=0.67). The corresponding TSH values were 143.4+/-20.0 and 132.0+/-22.0 mU/l (p=0.27). Following second surgery, only 4 patients achieved remission, the other 17 patients received one or more of the following therapies; RAI (10 patients), third surgery (5 patients), and/or external radiation (7 patients). Thirteen patients continued to have persistent disease and 4 patients showed progressive course of their disease (distant metastases or grossly palpable neck disease). In conclusion, second surgery for recurrent/persistent PTC leads to remission in only a minority of cases but the course of the disease tends to be stable in most cases.

123I isotope as a diagnostic agent in the follow-up of patients with differentiated thyroid cancer: comparison with post 131I therapy whole body scanning

Radioactive iodine (131I) plays a major role in the diagnosis and management of differentiated thyroid cancer (DTC); however, data on the use of the 123I isotope in DTC are limited. We compared 238 diagnostic whole body scans performed 24 h after oral ingestion of 185-555 MBq 123I with their corresponding 131I posttherapy whole body scans obtained 4-5 d after 131I therapy. We studied scans in 3 clinical situations: with the first 131I therapy, with the second 131I therapy, and in cases of elevated Tg and negative diagnostic scan. One hundred and seventy-seven pairs were obtained with the first 131I therapy and showed complete concordance between pretreatment and posttreatment scans in 166 pairs (concordance rate, 93.8%). Six other posttreatment scans showed more foci in the thyroid bed than the pretreatment scans, but no evidence of uptake in new areas. Only 5 posttreatment scans showed foci in new locations: 3 in cervical lymph nodes (CLN), 1 in the lung, and 1 new bone metastasis in a patient with known skeletal metastases. With the second 131I therapy, 34 pairs were obtained and showed complete concordance in 28 pairs (concordance rate, 82.4%). Five discordant pairs showed additional foci in areas that were already positive on pretreatment scans. Only 1 posttreatment scan showed a new bone metastasis in a different site from the bone metastases that were seen on its corresponding pretreatment scan. Of 27 pairs of scans in patients with elevated Tg and negative pretreatment scans, 15 posttreatment scans remained negative, 6 posttreatment scans showed an uptake in the thyroid bed, and 3 other posttreatment scans showed lung uptake in patients whose computed tomography scans of the chest showed only bronchiectasis (in 2 patients) and lung scarring (in the third patient) without evidence of lung metastases. Three posttreatment scans showed definite uptake (in thyroid bed, thyroid bed and lung, and CLN) compared with their corresponding pretreatment scans, which were initially reported negative but were retrospectively thought to have had faint uptake. In 56 pretreatment scans, the 123I diagnostic activity was 185 MBq, and the results showed complete concordance in 54 pairs. Two posttreatment scans showed additional uptake: 1 in the bone and 1 in CLN. These data suggest that pretreatment scanning using 123I is highly comparable to 131I posttreatment scanning and that 123I is an excellent diagnostic agent in DTC.