Johnson, Derek R.

Abstract Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a recently described epileptogenic tumor characterized by oligodendroglioma-like components, aberrant CD34 expression, and genetic MAPK pathway activation through alterations such as BRAF V600E mutation, and FGFR2-KIAA1598/CTNNA3 and FGFR3-TACC3 fusions. We report the molecular profiling of PLNTY in 9 patients, 7 female: 2 male, median age at diagnosis of 16 years (range, 5–34). All tumors were supratentorial with diagnostic morphological features of PLNTY including oligodendroglioma-like areas and strong diffuse CD34 immunostaining. Four (of 9; 44%) tumors were positive for BRAF V600E immunostain, indicating the presence of a BRAF V600E mutation. The 6 cases evaluated for IDH status were negative by IDH1-R132H immunostain (n=5; 3 BRAF V600E-negative and 2 BRAF V600E-positive) or by NGS (n=1; BRAF V600E-negative). Oncoscan chromosomal microarray performed in 5 BRAF V600E-negative tumors showed recurrent copy number changes including gain of whole chromosomes 5, 7, 8, 9, 12, 18, 19, 20, 21 and X, and loss of chromosomes 1, 2, 10q, 13, 22 and Xq. The 10q losses (n=2) were highly suggestive of an FGFR2-KIAA1598 and of a potentially novel FGFR2 underlying fusion event in one case each. Custom targeted neuro-oncology DNA and RNA NGS panel performed in 2 cases revealed a fusion similar to fusions previously reported in pilocytic astrocytoma: one with a KIAA1549-BRAF (exon 15-exon 9) fusion associated with a 7q34 ~785 kilobase deletion rather than the characteristic ~2 megabase duplication seen in pilocytic astrocytoma, and another with a QKI-NTRK2 (exon 6-exon 15) fusion associated with a 9q21 ~191 kilobase duplication disrupting NTRK2. The KIAA1549-BRAF fusion-positive case also had a TP53 mutation with loss of whole chromosome 17, suggesting TP53 complete inactivation. This study confirms that PLNTY is a low-grade neuroepithelial tumor with frequent MAPK pathway activation and expands the spectrum of MAPK activating alterations observed in PLNTY.

Abstract BACKGROUND 177Lu-Dotatate (177Lu-DOTA0-Tyr3-Octreotate) is a beta-particle emitting somatostatin analog recently FDA approved for the treatment of somastatin receptor-positive gastroenteropancreatic neuroendocrine tumors. Somatostatin receptors are highly expressed in almost all meningiomas, therefore 177Lu-Dotatate may be a reasonable treatment strategy for this disease. Furthermore, the short path length of the beta particle should allow for treatment of previously radiated patients with low risk of cerebral radiation necrosis. CASE STUDY: A 61 year-old male presented with a history of atypical meningioma (WHO grade II), recurrent as anaplastic meningioma (WHO grade III). His previous treatments included multiple surgical resections, fractionated radiation therapy, stereotactic radiosurgery, everolimus/octreotide LAR, bevacizumab and hydroxyurea. MRI imaging revealed rapid volumetric progression over the prior nine months with a near tripling in size from 29.9 cm3 to 80.4 cm3. In-111 octreotide confirmed the presence of somatostatin receptors within the tumor. 177Lu-Dotatate was administered intravenously at a dose of 200 millicuries per dose, every eight weeks for four cycles. Treatment was tolerated very well, with no significant adverse events. Tumor volume initially increased to 98.3 cm3 after cycle 1 of treatment, and subsequently decreased to 91.2 cm3 after cycle 2. Eight months after treatment onset, the tumor volume remained stable (93.4 cm3). CONCLUSION 177Lu-Dotatate may be a safe and effective strategy for the treatment of somastatin receptor-positive meningioma. The transient increase in tumor volume after the first dose in this case may have represented delayed treatment effect or pseudoprogression. A phase II clinical trial is currently being activated to determine the progression-free survival associated with 177Lu-Dotatate in patients with recurrent meningioma.

Abstract The treatment of resected brain metastasis has shifted away from the historical use of whole-brain radiotherapy (WBRT) toward adjuvant radiosurgery (stereotactic radiosurgery [SRS]) based on a recent prospective clinical trial demonstrating less cognitive decline with the use of SRS alone and equivalent survival as compared with WBRT. Whereas all level 1 evidence to date concerns single-fraction SRS for postoperative brain metastasis, there is emerging evidence that fractionated stereotactic radiotherapy (FSRT) may improve local control at the resected tumor bed. The lack of direct comparative data for SRS vs FSRT results in a diversity in clinical practice. In this article, Greenspoon and Roberge defend the use of SRS as the standard of care for resected brain metastasis, whereas Palmer and Brown argue for FSRT.

Abstract The treatment of newly diagnosed oligodendroglioma has been revolutionized in the past decade by multiple studies demonstrating that the addition of chemotherapy to radiation therapy results in a significant survival benefit. While the most direct evidence comes from clinical trials that utilized PCV, a chemotherapy regimen consisting of procarbazine, CCNU (lomustine), and vincristine, there is circumstantial evidence suggesting that the oral agent temozolomide (TMZ), which is both better tolerated and logistically simpler than PCV, may also be effective. The lack of currently available direct comparative data for PCV vs TMZ results in a diversity of practice. In this article, Ruff and Buckner argue for PCV as part of the standard-of-care regimen for newly diagnosed anaplastic oligodendroglioma, while Geurts and van den Bent defend the use of TMZ.