Priya Kumthekar

Efficacy and safety results of ABT-414 in combination with radiation and temozolomide in newly diagnosed glioblastoma

Background The purpose of this study was to determine the maximum tolerated dose (MTD), recommended phase II dose (RPTD), safety, and pharmacokinetics of ABT-414 plus radiation and temozolomide in newly diagnosed glioblastoma. ABT-414 is a first-in-class, tumor-specific antibody-drug conjugate that preferentially targets tumors expressing overactive epidermal growth factor receptor (EGFR). Methods In this multicenter phase I study, patients received 0.5-3.2 mg/kg ABT-414 every 2 weeks by intravenous infusion. EGFR alterations, O6-methylguanine-DNA methyltransferase (MGMT) promoter hypermethylation, and isocitrate dehydrogenase (IDH1) gene mutations were assessed in patient tumors. Distinct prognostic classes were assigned to patients based on a Molecular Classification Predictor model. Results As of January 7, 2016, forty-five patients were enrolled to receive ABT-414 plus radiation and temozolomide. The most common treatment emergent adverse events were ocular: blurred vision, dry eye, keratitis, photophobia, and eye pain. Ocular toxicity at any grade occurred in 40 patients and at grades 3/4 in 12 patients. RPTD and MTD were set at 2 mg/kg and 2.4 mg/kg, respectively. Among 38 patients with pretreatment tumor tested centrally, 39% harbored EGFR amplification, of which 73% had EGFRvIII mutation. Among patients with available tumor tissue (n = 30), 30% showed MGMT promoter methylation and none had IDH1 mutations. ABT-414 demonstrated an approximately dose proportional pharmacokinetic profile. The median duration of progression-free survival was 6.1 months; median overall survival has not been reached. Conclusion ABT-414 plus chemoradiation demonstrated an acceptable safety and pharmacokinetic profile in newly diagnosed glioblastoma. Randomized studies are ongoing to determine efficacy in newly diagnosed (NCT02573324) and recurrent glioblastoma (NCT02343406).

Mutant IDH1 and seizures in patients with glioma

Objective: Because the d-2-hydroxyglutarate (D2HG) product of mutant isocitrate dehydrogenase 1 (IDH1mut) is released by tumor cells into the microenvironment and is structurally similar to the excitatory neurotransmitter glutamate, we sought to determine whether IDH1mut increases the risk of seizures in patients with glioma, and whether D2HG increases the electrical activity of neurons. Methods: Three WHO grade II-IV glioma cohorts from separate institutions (total N = 712) were retrospectively assessed for the presence of preoperative seizures and tumor location, WHO grade, 1p/19q codeletion, and IDH1mut status. Rat cortical neurons were grown on microelectrode arrays, and their electrical activity was measured before and after treatment with exogenous D2HG, in the presence or absence of the selective NMDA antagonist, AP5. Results: Preoperative seizures were observed in 18%–34% of IDH1 wild-type (IDH1wt) patients and in 59%–74% of IDH1mut patients (p < 0.001). Multivariable analysis, including WHO grade, 1p/19q codeletion, and temporal lobe location, showed that IDH1mut was an independent correlate with seizures (odds ratio 2.5, 95% confidence interval 1.6–3.9, p < 0.001). Exogenous D2HG increased the firing rate of cultured rat cortical neurons 4- to 6-fold, but was completely blocked by AP5. Conclusions: The D2HG product of IDH1mut may increase neuronal activity by mimicking the activity of glutamate on the NMDA receptor, and IDH1mut gliomas are more likely to cause seizures in patients. This has rapid translational implications for the personalized management of tumor-associated epilepsy, as targeted IDH1mut inhibitors may improve antiepileptic therapy in patients with IDH1mut gliomas.

Low-grade glioma

Low-grade gliomas are slower growing than their high-grade counterparts. They account for 10-20 % of all primary brain tumors. Median survival is between 4.7 and 9.8 years. The goal of treatment is to prolong overall survival while maintaining good quality of life (QOL). Recent data favors early surgical resection. EOR is associated with delayed tumor recurrence and improved survival. Additional therapy with chemotherapy or radiation is indicated in patients with high-risk features. Lower doses (between 45 and 50.4 Gy) have been shown to be as effective without adverse effects compared to higher doses. Recent trials have shown benefit in combining chemotherapy with radiation compared to radiation alone. The optimal chemotherapeutic regimen (PCV or temozolomide (TMZ)) remains unknown, although TMZ is easier to administer and better tolerated by patients. Novel molecular markers including 1p/19q chromosomal codeletion and isocitrate dehydrogenase 1 (IDH1) mutation have been correlated with treatment response and survival.

Atypical meningioma: Randomized trials are required to resolve contradictory retrospective results regarding the role of adjuvant radiotherapy

BACKGROUND The role of postoperative radiation (RT) in atypical meningioma remains controversial. MATERIALS AND METHODS We report a retrospective review of outcomes and prognostic factor analysis in 158 patients treated between 2000 and 2010, and extensively review the literature. RESULTS Following resection, 23 patients received immediate RT, whereas 135 did not. Median progression-free survival (PFS) with and without RT was 59 (range 43-86) and 88 (range 64-123) months. For Simpson grade (G) 1-3 resection, with and without RT, median PFS was 48 (2-80) versus 96 (88-123) months and for Simpson G4, it was 59 (6-86) versus 47 (15-104) months (P = 0.4). The rate of 5-year overall survival (OS) with and without RT was 89% and 83%, respectively. On univariate analysis, Simpson G4 (HR 3.2, P = 0.0006) and brain invasion (HR 2.2, P = 0.03) were significantly associated with progression, whereas age >60 years (HR 9.7, P = 0.002), mitoses >5 per 10 high-power field (0.2, P = 0.0056), and Simpson G4 (HR 2.4, P = 0.07) were associated with higher risk of death. We summarized 22 additional reports, which provide very divergent results regarding the benefit of RT. CONCLUSIONS In our series, adjuvant RT is surprisingly associated with worse PFS and OS, and this is more likely to be due to selection bias of referring tumors with more aggressive characteristics such as elevated Ki-67 and brain invasion for adjuvant RT, rather than a direct causal effect of adjuvant RT. Although there is a trend toward improved PFS with adjuvant RT after subtotal resection, no improvement was noted in OS. Multivariate analysis did not yield statistical significance for any of the factors including Simpson grades of resection, adjuvant RT, or six pathological defining features. The relatively divergent results in the literature are most likely explained by patient selection variability; therefore, randomized trials to adequately address this question are clearly necessary.

Developmental therapeutics for patients with breast cancer and central nervous system metastasis: current landscape and future perspectives

Breast cancer is the second-leading cause of metastatic disease in the central nervous system (CNS). Recent advances in the biological understanding of breast cancer have facilitated an unprecedented increase of survival in a subset of patients presenting with metastatic breast cancer. Patients with HER2 positive (HER2+) or triple negative breast cancer are at highest risk of developing CNS metastasis, and typically experience a poor prognosis despite treatment with local and systemic therapies. Among the obstacles ahead in the realm of developmental therapeutics for breast cancer CNS metastasis is the improvement of our knowledge on its biological nuances and on the interaction of the blood–brain barrier with new compounds. This article reviews recent discoveries related to the underlying biology of breast cancer brain metastases, clinical progress to date and suggests rational approaches for investigational therapies.

Safety, Pharmacokinetics and Antitumor Response of Depatuxizumab Mafodotin as Monotherapy or in Combination with Temozolomide in Patients with Glioblastoma

Background We recently reported an acceptable safety and pharmacokinetic profile of depatuxizumab mafodotin (depatux-m), formerly called ABT-414, plus radiation and temozolomide in newly diagnosed glioblastoma (arm A). The purpose of this study was to evaluate the safety and pharmacokinetics of depatux-m, either in combination with temozolomide in newly diagnosed or recurrent glioblastoma (arm B) or as monotherapy in recurrent glioblastoma (arm C). Methods In this multicenter phase I dose escalation study, patients received depatux-m (0.5-1.5 mg/kg in arm B, 1.25 mg/kg in arm C) every 2 weeks by intravenous infusion. Maximum tolerated dose (MTD), recommended phase II dose (RP2D), and preliminary efficacy were also determined. Results Thirty-eight patients were enrolled as of March 1, 2016. The most frequent toxicities were ocular, occurring in 35/38 (92%) patients. Keratitis was the most common grade 3 adverse event observed in 6/38 (16%) patients; thrombocytopenia was the most common grade 4 event seen in 5/38 (13%) patients. The MTD was set at 1.5 mg/kg in arm B and was not reached in arm C. RP2D was declared as 1.25 mg/kg for both arms. Depatux-m demonstrated a linear pharmacokinetic profile. In recurrent glioblastoma patients, the progression-free survival (PFS) rate at 6 months was 30.8% and the median overall survival was 10.7 months. Best Response Assessment in Neuro-Oncology responses were 1 complete and 2 partial responses. Conclusion Depatux-m alone or in combination with temozolomide demonstrated an acceptable safety and pharmacokinetic profile in glioblastoma. Further studies are currently under way to evaluate its efficacy in newly diagnosed (NCT02573324) and recurrent glioblastoma (NCT02343406).

Improving vaccine efficacy against malignant glioma

ABSTRACT The effective treatment of adult and pediatric malignant glioma is a significant clinical challenge. In adults, glioblastoma (GBM) accounts for the majority of malignant glioma diagnoses with a median survival of 14.6 mo. In children, malignant glioma accounts for 20% of primary CNS tumors with a median survival of less than 1 y. Here, we discuss vaccine treatment for children diagnosed with malignant glioma, through targeting EphA2, IL-13Rα2 and/or histone H3 K27M, while in adults, treatments with RINTEGA, Prophage Series G-100 and dendritic cells are explored. We conclude by proposing new strategies that are built on current vaccine technologies and improved upon with novel combinatorial approaches.

Gene Delivery in Neuro-Oncology

Purpose of ReviewGlioblastoma multiforme (GBM) is the most common primary malignant brain tumor in adults with a dismal prognosis despite aggressive multimodal management thus novel treatments are urgently needed. Gene therapy is a versatile treatment strategy being investigated in multiple cancers including GBM. In gene therapy, a variety of vectors or “carriers” are used to deliver genes designed for different anti-tumoral effects. Gene delivery vehicles and approaches to treatment will be addressed in this review.Recent FindingsThe most commonly studied vectors are viral based, however, driven by advances in biomedical engineering, mesenchymal and neural stem cells, as well as multiple different types of nanoparticles have been developed to improve tumor tropism and also increase gene transfer into tumor cells. Different genes have been studied including suicide genes, which convert non-toxic prodrug into cytotoxic drug; immunomodulatory genes, which stimulate the immune system; and tumor suppressor genes which repair the defect that allow cells to divide unchecked.SummaryGene therapy may be a promising treatment strategy in neuro-oncology as it is versatile and flexible due to the ability to tailor vectors and genes for specific therapeutic activity. Pre-clinical studies and clinical trials have demonstrated feasibility and safety of gene therapy; however, further studies are required to determine efficacy.

Systemic therapies in the treatment of non-small-cell lung cancer brain metastases

Non-small-cell lung cancer (NSCLC) brain metastases are common. Even though there are various subsets of NSCLC with molecular alterations, there is a common theme of brain metastases. Current treatment modalities are suboptimal. Systemic therapies for the treatment of NSCLC brain metastases have been explored and recent advances may pave the way for their successful employment in this patient population. While no specific agents have been associated with a marked benefit, stability of disease as well as radiographic responses have been noted in some patients. Biological activity of systemic therapies in some patients with NSCLC brain metastases raises hope for future advances and supports further investigation for this patient population with limited treatment options.

Differential Response of Glioma Stem Cells to Arsenic Trioxide Therapy Is Regulated by MNK1 and mRNA Translation

Mesenchymal (MES) and proneural (PN) are two distinct glioma stem cell (GSC) populations that drive therapeutic resistance in glioblastoma (GBM). We screened a panel of 650 small molecules against patient-derived GBM cells to discover compounds targeting specific GBM subtypes. Arsenic trioxide (ATO), an FDA-approved drug that crosses the blood–brain barrier, was identified as a potent PN-specific compound in the initial screen and follow-up validation studies. Furthermore, MES and PN GSCs exhibited differential sensitivity to ATO. As ATO has been shown to activate the MAPK-interacting kinase 1 (MNK1)-eukaryotic translation initiation factor 4E (eIF4E) pathway and subsequent mRNA translation in a negative regulatory feedback manner, the mechanistic role of ATO resistance in MES GBM was explored. In GBM cells, ATO-activated translation initiation cellular events via the MNK1–eIF4E signaling axis. Furthermore, resistance to ATO in intracranial PDX tumors correlated with high eIF4E phosphorylation. Polysomal fractionation and microarray analysis of GBM cells were performed to identify ATOs effect on mRNA translation and enrichment of anti-apoptotic mRNAs in the ATO-induced translatome was found. Additionally, it was determined that MNK inhibition sensitized MES GSCs to ATO in neurosphere and apoptosis assays. Finally, examination of the effect of ATO on patients from a phase I/II clinical trial of ATO revealed that PN GBM patients responded better to ATO than other subtypes as demonstrated by longer overall and progression-free survival. Implications: These findings raise the possibility of a unique therapeutic approach for GBM, involving MNK1 targeting to sensitize MES GSCs to drugs like arsenic trioxide. Mol Cancer Res; 16(1); 32–46. ©2017 AACR.