Yasuji Miyakita

Revisiting TP53 Mutations and Immunohistochemistry—A Comparative Study in 157 Diffuse Gliomas

The association between p53 immunohistochemistry and TP53 mutation status has been controversial. The present study aims to re‐evaluate the efficacy of p53 immunohistochemistry to predict the mutational status of TP53. A total of 157 diffuse gliomas (World Health Organization grades II–IV) were assessed by exon‐by‐exon DNA sequencing from exon 4 through 10 of TP53 using frozen tissue samples. Immunohistochemistry with a p53 antibody (DO‐7) on paired formalin‐fixed paraffin‐embedded materials was assessed for the extent and intensity of reactivity in all cases. A total of 72 mutations were detected in 66 samples. They included 60 missense mutations, five nonsense mutations, four deletions and three alterations in the splicing sites. A receiver operating characteristic curve analysis revealed that strong p53 immunoreactivity in more than 10% of cells provided the most accurate prediction of mutation. Using this cutoff value, 52 of 55 immunopositive cases harbored a mutation, whereas only 14 of 102 immunonegative cases showed mutations, sensitivity and specificity being 78.8% and 96.7%. Tumors with frameshift mutations frequently showed negative immunostaining. Staining interpretation by an independent observer yielded comparable accuracy. We thus propose p53 immunohistochemistry as a moderately sensitive and highly specific marker to predict TP53 mutation.

Recurrent mutations of CD79B and MYD88 are the hallmark of primary central nervous system lymphomas

Primary central nervous system lymphoma (PCNSL) manifest aggressive clinical behaviour and have poor prognosis. Although constitutive activation of the nuclear factor‐κB (NF‐κB) pathway has been documented, knowledge about the genetic alterations leading to the impairment of the NF‐κB pathway in PCNSLs is still limited. This study was aimed to unravel the underlying genetic profiles of PCNSL.

IDH1/2 mutation is a prognostic marker for survival and predicts response to chemotherapy for grade II gliomas concomitantly treated with radiation therapy

Reliable prognostic biomarkers of grade II gliomas remain unclear. This study aimed to examine the role of mutations of isocitrate dehydrogenase (IDH1/2), 1p/19q co-deletion, and clinicopathological factors in patients with grade II glioma who were primarily treated with radiotherapy or chemoradiotherapy after surgery. Seventy-two consecutive patients, including 49 cases of diffuse astrocytomas (DA), 4 oligodendrogliomas (OL) and 19 oligoastrocytomas (OA), who underwent treatment from 1991 to 2010 at a single institution were examined. The overall survival (OS) of the DA patients (8.3 years) was significantly shorter than that of the OL and OA patients (11.7 years). IDH1/2 mutations were found in 46.9% of the DA patients and 82.6% of the OL and OA patients. The progression-free survival (PFS) and OS of the patients with IDH1/2 mutations (8.4 and 16.3 years) were significantly longer than those of the patients without IDH1/2 mutations (3.3 and 4.5 years). Among the patients with IDH1/2 mutations, those who were initially treated with chemoradiotherapy including nimustine hydrochloride (ACNU), had significantly longer PFS than those treated with radiotherapy alone, whereas no significant difference in PFS was observed between the chemoradiotherapy and radiotherapy groups in the patients without IDH1/2 mutations. Oligodendroglial tumors, age <40 years, initial Karnofsky performance status (KPS) ≥80, and IDH1/2 mutations were favorable prognostic factors regarding PFS and OS. IDH1/2 mutation was a predictive factor of response to chemoradiotherapy in grade II gliomas. Patients with IDH1/2 mutations may benefit more from chemoraiotherapy than those without IDH1/2 mutations.

A combination of TERT promoter mutation and MGMT methylation status predicts clinically relevant subgroups of newly diagnosed glioblastomas

The prognostic impact of TERT mutations has been controversial in IDH-wild tumors, particularly in glioblastomas (GBM). The controversy may be attributable to presence of potential confounding factors such as MGMT methylation status or patients’ treatment. This study aimed to evaluate the impact of TERT status on patient outcome in association with various factors in a large series of adult diffuse gliomas. We analyzed a total of 951 adult diffuse gliomas from two cohorts (Cohort 1, n = 758; Cohort 2, n = 193) for IDH1/2, 1p/19q, and TERT promoter status. The combined IDH/TERT classification divided Cohort 1 into four molecular groups with distinct outcomes. The overall survival (OS) was the shortest in IDH wild-type/TERT mutated groups, which mostly consisted of GBMs (P < 0.0001). To investigate the association between TERT mutations and MGMT methylation on survival of patients with GBM, samples from a combined cohort of 453 IDH-wild-type GBM cases treated with radiation and temozolomide were analyzed. A multivariate Cox regression model revealed that the interaction between TERT and MGMT was significant for OS (P = 0.0064). Compared with TERT mutant-MGMT unmethylated GBMs, the hazard ratio (HR) for OS incorporating the interaction was the lowest in the TERT mutant-MGMT methylated GBM (HR, 0.266), followed by the TERT wild-type-MGMT methylated (HR, 0.317) and the TERT wild-type-MGMT unmethylated GBMs (HR, 0.542). Thus, patients with TERT mutant-MGMT unmethylated GBM have the poorest prognosis. Our findings suggest that a combination of IDH, TERT, and MGMT refines the classification of grade II-IV diffuse gliomas.

TERT promoter mutations rather than methylation are the main mechanism for TERT upregulation in adult gliomas

observed TERT upregulation in some tumors without mutations in the hotspots. A small subset of tumors had neither TERT nor ATRX mutations [9]. Recently, it has been reported that DNA hypermethylation of the TERT promoter is a common finding in pediatric brain tumors and associated with TERT upregulation [2]. Hypermethylation of the TERT CpG island has been linked to increased expression levels in other cancers [2, 4, 5]. We, therefore, studied the association between TERT methylation and TERT mRNA levels to investigate the possibility that DNA methylation serves as an alternative mechanism for TERT upregulation in adult gliomas. Eighty-eight adult gliomas samples with known TERT promoter mutation status suitable for mRNA expression analysis, 43 of which had mutations, were examined in this study. TERT mRNA expression of 88 tumors including 48 primary glioblastomas that have previously been investigated was analyzed as described [1]. The methylation status of three regions within the CpG island (Regions 1–3; Fig. 1a), including the region methylated in pediatric tumors (Region 1) and the region that contains the two mutation hotspots (Region 3), was assessed by pyrosequencing of the PCR products amplified from bisulfitemodified genomic DNA. The methylation status was represented either as the mean methylation levels of all CpGs in each region or as a dichotomous variable (hypermethylated or unmethylated) at each region using the cut-off value of 15 % according to Castelo-Branco et al. [2]. More detailed information is available in Supplementary Materials and Methods. There was no significant difference in the mean methylation levels or the frequency of hypermethylated tumors in any of the regions between tumors of the different histological subtypes (astrocytic tumor, oligodendroglial tumor and glioblastoma), or between those with and without Telomere lengthening (TL) is mandatory for infinite proliferation of many cancer cells. This is generally achieved either by telomerase activation or in some cases by telomerase-independent alternative lengthening of telomeres (ALT) [3]. Recently, recurrent mutations at two hotspots termed C228T and C250T in the promoter region of TERT, a catalytic subunit of telomerase, have been reported in various types of cancers [1, 6, 7, 9, 12]. These mutations result in upregulation of TERT expression [1, 7], which is required for telomerase activation [11]. TERT promoter mutations are particularly common in adult gliomas [1, 9]. It is also known that a subset of astrocytomas harbors mutations of ATRX, which could lead to ALT [10]. We have previously shown that glioblastomas with TERT mutation had TERT mRNA upregulation [1]. We have also

p53 abnormality and tumor invasion in patients with malignant astrocytoma

Malignant astrocytomas are characterized by diffusely infiltrating nature, and the abnormality of p53 is a cytogenetic hallmark of astrocytic tumors. To elucidate the relationship between p53 abnormality and invasiveness of the tumors, we studied mutation and protein expression of p53 in 48 consecutive patients with malignant astrocytoma (14 anaplastic astrocytomas and 34 glioblastoma multiformes). The tumors were classified into three categories according to the features of magnetic resonance imaging, and 5, 7, and 36 tumors were classified into diffuse, multiple, and single type, respectively. We then examined how these tumor types correlate with MIB-1 staining index, TP53 gene mutation, and p53 protein expression. We found that p53 immunopositivity or TP53 mutation was frequently observed in diffuse and multiple types. These abnormalities of p53 were also associated with high MIB-1 staining index and strong expression of vascular endothelial growth factor. Furthermore, diffuse- and multiple-type tumors were significantly correlated with poor progression-free survival, whereas only multiple-type tumors were significantly correlated with poor overall survival. As diffuse and multiple features on imaging modalities represent invasive characteristics of the tumors, p53 abnormalities may affect the invasive and aggressive nature of malignant astrocytomas.

Multinodular and vacuolating neuronal tumor of the cerebrum

Multinodular and vacuolating neuronal tumors of the cerebrum (MVNT) are superficial neuronal tumors in adults that were first documented in 2013. Herein, we report a case of MNVT involving a 37-year-old man who presented with an epileptogenic, superficial solid lesion in the left parietal lobe. Histomorphology of the resected specimen was characterized by nodular lesions with vacuolation. Nodules comprised irregular proliferation of neuronal cells, which ranged from ganglion-like forms to those with indistinct lineage. Immunohistochemical analysis showed that the lesional cells stained positively for HuC/HuD, synaptophysin, and Olig2, and negatively for NeuN, neurofilament, chromogranin A, GFAP, CD34, IDH1R132H, and BRAFV600E. Eighteen months following surgery, the patient is well and without neurological deficits. MVNTs are distinctive tumors that should be differentiated from ganglion cell tumors, dysembryoplastic neuroepithelial tumors, and malformation of cortical development.

Long-term follow-up of vanishing tumors in the brain: How should a lesion mimicking primary CNS lymphoma be managed?

OBJECTIVES The spontaneous disappearance of a tumor is referred to as a vanishing tumor. Most vanishing tumors in the brain are eventually diagnosed as malignant tumors or multiple sclerosis. However, their long-term clinical course remains unclear. This study aims to elucidate the management of vanishing tumors in the brain. PATIENTS AND METHODS We defined a vanishing tumor as a case in which the tumor spontaneously disappeared or decreased to less than 70% of the initial tumor volume before definitive diagnosis and treatment (other than steroid treatment). Ten cases of vanishing tumors are reviewed. RESULTS Nine patients underwent biopsy at least once. Five patients, all of whom had malignant tumors (primary central nervous system lymphoma: 4, germinoma: 1) that recurred in 4-45 months (median: 7 months), underwent a second biopsy after the reappearance of the tumors. Five patients (tumefactive demyelinating lesion: 1, undiagnosed: 4) who had no relapse are alive, and their median follow-up time is 44 months. No cases have yet been reported of malignant brain tumors that recurred more than 5 years after spontaneous regression. CONCLUSIONS Patients with vanishing tumors should be followed up carefully by magnetic resonance imaging for at least 5 years, even after the disappearance of an enhancing lesion.

Acute lymphoblastic leukemia after temozolomide treatment for anaplastic astrocytoma in a child with a germline TP53 mutation

We present a case of a 12‐year‐old female with a germline TP53 mutation who presented with anaplastic astrocytoma and subsequent acute lymphoblastic leukemia (ALL) 13 months after starting treatment with temozolomide (TMZ). The patient had no family history of malignancy except her grand father and his siblings. Although alkylating agents such as TMZ are known to induce secondary hematologic malignancy, only several cases of treatment‐related acute leukemia have been reported after TMZ‐alone chemotherapy for malignant gliomas. We demonstrate a rare case of TMZ‐related ALL in a child with glioma possibly associated with a germline TP53 mutation. Pediatr Blood Cancer. 2010;55:577–579.

Secondary hematological malignancies associated with temozolomide in patients with glioma

BACKGROUND The alkylating agent temozolomide (TMZ) is widely used for the treatment of gliomas. Although reports of treatment-related myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), and acute lymphoblastic leukemia (ALL) associated with TMZ are accumulating, it remains unclear whether TMZ has the same leukemogenic potential as other alkylating agents. METHODS We performed a single-institution retrospective analysis using a database of 359 glioma patients given nimustine (ACNU)-based therapy, TMZ-based therapy, or combination therapy, who were followed up for a minimum of 2 months, between January 1990 and December 2009, at the National Cancer Center Hospital in Japan. RESULTS Of the 359 patients, 225 received ACNU alone or ACNU plus other chemotherapeutic drugs (ACNU-based group; median follow-up period, 31.4 mo), 63 patients received ACNU-based therapy followed by TMZ therapy (ACNU-TMZ group; median follow-up period, 19.1 mo), and 71 patients received TMZ alone or TMZ plus other chemotherapeutic drugs (TMZ-based group; median follow-up period, 16.9 mo). Three patients in the ACNU-based group developed MDS/AML (incidence rate: 2.9 cases per 1000 person-years), 2 patients in the ACNU-TMZ group developed MDS/AML (13.0 cases per 1000 person-years), and 1 patient in the TMZ-based group developed ALL (9.9 cases per 1000 person-years). CONCLUSIONS Despite the limitations of this study, published reports and our results suggest that TMZ induces secondary hematological malignancies, particularly ALL, and might shorten the latency period when used in combination with other chemotherapeutic agents.