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Differentiation of true tumor progression (TP) from pseudoprogression (PsP) is a major unmet need in patients with glioblastoma. [18F]Fluciclovine is a synthetic amino acid PET radiotracer that is FDA-approved in biochemical recurrence in prostate cancer. The study aim was to assess the value of [18F]Fluciclovine PET in differentiation of histologically confirmed (“true”) TP and PsP in post-treatment of glioblastoma. METHODS: 23 patients with glioblastoma with new contrast-enhancing lesions or lesions showing increased enhancement ( > 25% increase) on standard MRI after completion of radiation underwent 60-minutes dynamic [18F]Fluciclovine PET imaging. Patients subsequently underwent resection of enhancing lesion and tumor percentage vs. treatment-related changes were quantified on histopathology. Patients were considered "true” TP if tumor represented ≥ 50% of the resected specimen, mixed TP-PsP if < 50% and > 10%, and PsP if tumor represented ≤ 10%. Summed 30- to 40-minute post-injection PET images were used to measure SUVpeak and SUVmax (g/mL units). RESULTS: 15 patients with “true” TP, 3 with mixed TP-PsP, and 5 with PsP were included. There was a positive correlation between SUVpeak by PET and tumor percentage by histology (Rho= 0.56, p= 0.006). Patients who demonstrated “true” TP had significantly higher SUVpeak compared to patients with histological PsP (4.8±1.6 vs 2.9± 1.0, p= 0.02, AUC= 0.91, n=20). SUVpeak cut-off of 3.3 provided 93% sensitivity, 80% specificity, and 90% accuracy for differentiation of “true” TP from PsP. Patients with “true” TP/mixed TP-PsP also had significantly higher SUVpeak than patients with PsP (4.6±1.5 vs 2.9± 1.0, p= 0.03, AUC= 0.88, n=23). SUVmax and partial volume-corrected SUVpeak and SUVmax exhibited similar performance. CONCLUSION: Our results indicated that [18F]Fluciclovine PET imaging can accurately differentiate “true” TP from PsP. Further studies are required to confirm these promising early results and determine optimal criteria for interpreting [18F]Fluciclovine PET to distinguish PsP from TP.

Background. Multi-omic data, i.e., clinical measures, radiomic, and genetic data, capture multi-faceted tumor characteristics, contributing to a comprehensive patient risk assessment. Here, we investigate the additive value and independent reproducibility of integrated diagnostics in prediction of overall survival (OS) in newly diagnosed, treatment-naïve, IDH-wildtype GBM patients, by combining conventional and deep learning methods.Methods. Conventional radiomics and deep learning features were extracted from pre-operative multi-parametric MRI of 516 GBM patients. SVM classifiers were trained on the discovery cohort (n=404) to categorize patient groups of high-risk (OSradiomics) was produced. Multivariate Cox-PH models were generated for the replication cohort, first based on clinical measures solely, and then by layering on radiomics and molecular information.Results. Evaluation of the high-risk and low-risk classifiers in the discovery/replication cohorts revealed AUCs of 0.78 (95%CI:0.70–0.85)/0.75 (95%CI:0.64–0.79) and 0.75 (95%CI: 0.65–0.84)/0.63 (95%CI: 0.52–0.71), respectively. Cox-PH modeling showed a concordance index of 0.65 (95%CI:0.6–0.7) for clinical data, 0.70 (95%CI:0.65–0.75) for clinical and radiomics, 0.72 (95%CI:0.68–0.77) for clinical, MGMT methylation, and radiomics, and 0.75 (95%CI:0.72–0.79) for the combination of all omics, i.e., clinical, MGMT methylation, radiomics, and genomics.Conclusions. This study signifies the value of integrated diagnostics for improved prediction of OS in GBM. Our multi-omic survival prediction tool is easily scalable and can be used for more effective clinical trial stratification.

Young adults with isocitrate-dehydrogenase wild-type (IDH-WT) glioblastoma (GBM) represent a rare, understudied population compared to pediatric high-grade glioma, IDH-mutant GBM, or IDH-WT GBM in older patients. We aimed to explore the prognostic impact of epidermal growth factor receptor copy number gain (EGFR CN gain), one of the most common genetic alterations in IDH-WT glioma, in young adults with IDH-WT GBM. We performed a retrospective cohort study of patients 18–45 years old with newly diagnosed, IDH-WT GBM whose tumors underwent next-generation sequencing at our institution between 2014 and 2018. The impact of EGFR CN gain on time to tumor progression (TTP) and overall survival (OS) was assessed. A validation cohort of patients 18–45 years old with IDH-WT GBM was analyzed from The Cancer Genome Atlas (TCGA). Ten of 28 patients (36%) from our institution had EGFR CN gain, which was associated with shorter TTP (median 6.5 vs. 11.9 months; p = 0.06) and OS (median 16.3 vs. 23.5 months; p = 0.047). The negative prognostic impact of EGFR CN gain on OS persisted in a multivariate model (HR 6.40, 95% CI 1.3–31.0, p = 0.02). In the TCGA cohort (N = 43), EGFR CN gain was associated with shorter TTP and worse OS, although these did not reach statistical significance (TTP, median 11.5 vs. 14.4 months, p = 0.18; OS, median 23.6 vs. 27.8 months; p = 0.18). EGFR CN gain may be associated with inferior outcomes in young adults with newly diagnosed, IDH-WT GBM, suggesting a potential role for targeting EGFR in this population.

BACKGROUND We have previously demonstrated that high baseline plasma cfDNA concentration is associated with poor survival in patients with newly diagnosed GBM. The mechanism of this association remains unknown. To explore whether differences in the immune landscape between high- vs. low-cfDNA patients may play a role in their divergent clinical outcomes, we phenotyped tumors from patients with high vs. low cfDNA using mass cytometry by time of flight (CyTOF). METHODS We performed CyTOF on frozen tumor infiltrate suspension from a pilot cohort of patients with previously untreated GBM with known baseline plasma cfDNA concentration (Bagley, Clin Cancer Res 2020). CyTOF was used to simultaneously measure expression of 39 molecules related to immune cell lineage, differentiation state, and function. Differences in immune cell infiltrates between high- and low-cfDNA patients were assessed using Mann-Whitney U tests. RESULTS Four patients with high cfDNA (median 57, range 33-90 ng/mL) were compared to six patients with low cfDNA (median 12, range 7-16 ng/mL). Immune cell infiltrates with increased adaptive cells (high monocytes and T cells, p=0.05) were present in high-cfDNA compared to low-cfDNA patients. While > 70% of the infiltrating T cells were exhausted in both groups, the pattern of exhaustion was significantly different in high- vs. low-cfDNA patients, with less CXCR5+CD69+ and more CXCR5-CD69- (p=0.008) progenitor exhausted T cells in cfDNA-high patients. CONCLUSIONS In this GBM pilot study, we demonstrated differences in the tumor immune infiltrate in patients with high vs. low baseline plasma cfDNA concentration. Preclinical studies will be needed to determine if this explains the association between high plasma cfDNA and poor outcomes previously observed in patients. Our results may have implications for the use of cfDNA concentration as a predictive biomarker for immunotherapy, as tumors with more intermediate progenitor (CXCR5-CD69-) exhausted T cells may respond better to PD-1 checkpoint blockade.

PURPOSE Decision making about the best course of treatment for glioblastoma patients becomes challenging when a new enhancing lesion appears in the vicinity of the surgical bed on follow-up MRI (after maximal safe tumor resection and chemoradiation), raising concerns for tumor progression (TP). Literature indicates 30-50% of these new lesions describe primarily treatment-related changes (TRC). We hypothesize that quantitative analysis of specific and sensitive features extracted from multi-parametric MRI (mpMRI) via machine learning (ML) techniques may yield non-invasive imaging signatures that distinguish TP from TRC and facilitate better treatment personalization. METHODS We have generated an ML model on a retrospective cohort of 58 subjects, and prospectively evaluated on an independent cohort of 58 previously unseen patients who underwent second resection for suspicious recurrence and had availability of advanced mpMRI (T1, T1-Gd, T2, T2-FLAIR, DTI, DSC). The features selected by our retrospective model, representing principal components analysis of intensity distributions, morphological, statistical, and texture descriptors, were extracted from the mpMRI of the prospective cohort. Integration of these features revealed signatures distinguishing between TP, mixed response, and TRC. Independently, a board-certified neuropathologist evaluated the resected tissue by blindly classifying it in the above three categories, based on mitotic figures, pseudopalisading necrosis, geographic necrosis, dystrophic calcification, vascular changes, and Ki67. RESULTS Tissues classified as TRC by the neuropathologist were associated with imaging phenotypes of lower angiogenesis (DSC-derived features), lower cellularity (DTI-derived features), and higher water concentration (T2, T2-FLAIR features). Our ML model characterized TP with 78% accuracy (sensitivity:86%, specificity:70%, AUC:0.80 (95%CI, 0.68-0.92)) and TRC with 81% accuracy (sensitivity:80%, specificity:81%, AUC:0.87 (95%CI, 0.72-1.00)). CONCLUSION Our proposed ML model reveals distinct non-invasive markers of TP and TRC, directly associated with histopathological changes in prospective glioblastoma patients. Reliable stratification of TP and TRC entities may help to noninvasively determine whether the course of treatment should change.

The prognostic impact of the histopathologic features of recurrent glioblastoma surgical specimens is unknown. We sought to determine whether key histopathologic characteristics in glioblastoma tumors resected after chemoradiotherapy are associated with overall survival (OS). The following characteristics were quantified in recurrent glioblastoma specimens at our institution: extent of viable tumor (accounting for % of specimen comprised of tumor and tumor cellularity), mitoses per 10 high-power fields (0, 1–10, > 10), Ki-67 proliferative index (0–100%), hyalinization (0–6; none to extensive), rarefaction (0–6), hemosiderin (0–6), and % of specimen comprised of geographic necrosis (0–100%; converted to 0–6 scale). Variables associated with OS in univariate analysis, as well as age, eastern cooperative oncology group performance status (ECOG PS), extent of repeat resection, time from initial diagnosis to repeat surgery, and O6-methylguanine-DNA methyltransferase promoter methylation, were included in a multivariable Cox proportional hazards model. 37 specimens were assessed. In a multivariate model, high Ki-67 proliferative index was the only histopathologic characteristic associated with worse OS following repeat surgery for glioblastoma (hazard ratio (HR) 1.3, 95% CI 1.1–1.5, p = 0.003). Shorter time interval from initial diagnosis to repeat surgery (HR 1.11, 95% CI 1.02–1.21, p = 0.016) and ECOG PS ≥ 2 (HR 4.19, 95% CI 1.72–10.21, p = 0.002) were also independently associated with inferior OS. In patients with glioblastoma undergoing repeat resection following chemoradiotherapy, high Ki-67 index in the recurrent specimen, short time to recurrence, and poor PS are independently associated with worse OS. Histopathologic quantification of viable tumor versus therapy-related changes has limited prognostic influence.

Background We aimed to determine whether plasma cell-free DNA (cfDNA) concentration is associated with survival in patients with isocitrate dehydrogenase (IDH) wild-type glioblastoma (GBM). Methods Pre-operative and post-chemoradiotherapy blood samples were prospectively collected from patients with newly diagnosed IDH wild-type GBM. Patients underwent surgical resection or biopsy and received adjuvant radiotherapy with concomitant temozolomide. Cell-free DNA (cfDNA) was isolated from plasma and quantified using SYBR Green-based q polymerase chain reaction (qPCR). Results Sixty-two patients were enrolled and categorized into high vs. low cfDNA groups relative to the pre-operative median value (25.2 ng/mL, range 5.7–153.0 ng/mL). High pre-operative cfDNA concentration was associated with inferior PFS (median progression-free survival (PFS), 3.4 vs. 7.7 months; log-rank P = .004; hazard ratio [HR], 2.19; 95% CI, 1.26–3.81) and overall survival (OS) (median OS, 8.0 vs. 13.9 months; log-rank P = .01; HR, 2.43; 95% CI, 1.19–4.95). After adjusting for risk factors, including O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status, pre-operative cfDNA remained independently associated with PFS (HR, 2.70; 95% CI, 1.50–4.83; P = .001) and OS (HR, 2.65; 95% CI, 1.25–5.59; P = .01). Post-hoc analysis of change in cfDNA post-chemoradiotherapy compared to pre-surgery (n = 24) showed increasing cfDNA concentration was associated with worse PFS (median, 2.7 vs. 6.0 months; log-rank P = .003; HR, 4.92; 95% CI, 1.53–15.84) and OS (median, 3.9 vs. 19.4 months; log-rank P < .001; HR, 7.77; 95% CI, 2.17–27.76). Conclusions cfDNA concentration is a promising prognostic biomarker for patients with IDH wild-type GBM. Plasma cfDNA can be obtained noninvasively and may enable more accurate estimates of survival and effective clinical trial stratification.

BACKGROUND Novel T cell-enabling therapies, in combination with checkpoint inhibition, may improve OS in GBM. INO-5401 (synthetic DNA plasmids encoding hTERT, WT-1, PSMA) plus INO-9012 (synthetic DNA plasmid encoding IL-12), and the PD-1 immune checkpoint inhibitor cemiplimab, is given to patients with newly diagnosed GBM to evaluate tolerability, efficacy and immunogenicity. METHODS Phase I/II, single arm, 2 cohort study (A: MGMT unmethylated, B: MGMT methylated). Primary endpoint is safety; efficacy and immunogenicity are secondary. Nine mg INO-5401 plus 1 mg INO-9012 (every 3 weeks x 4 doses, then Q9W) is given IM with EP by CELLECTRA® 2000 with cemiplimab (350 mg IV Q3W). RT is given as 40 Gy over 3 weeks. TMZ is given with radiation (all patients), and adjuvantly (Cohort B only). RESULTS Fifty-two subjects enrolled: 32 in Cohort A; 20 in Cohort B. 35% women; median age 60 years (19–78 years). The adverse event profile is consistent with single-agent (INO-5401, INO-9012, EP and cemiplimab) reported events. OS at 12 months was 84.4% (Cohort A) and 85% (Cohort B). OS at 18 months in Cohort A is 50% (95% CI 31.9 - 68.1); median OS is 17.9 months (14.5 - NR); Cohort B OS18 and median OS will be presented. Tumor gene transcripts at diagnosis confirmed expression of INO-5401 antigens. Peripheral immune responses following INO-5401 revealed antigen-specific T cell responses by Interferon gamma ELISpot and flow cytometry, including cytokine production and expansion of antigen specific CD8+T cells with lytic potential. CONCLUSIONS INO-5401 + INO-9012, a novel DNA plasmid immunotherapy, demonstrates acceptable risk/benefit and generates robust systemic immune responses to encoded tumor antigens when administered with cemiplimab and RT/TMZ in newly diagnosed GBM patients. Overall survival is encouraging. Clinical trial information: NCT03491683.

A case of a true dual-genotype IDH-mutant oligoastrocytoma with two different cell types within a single mass in a young woman is presented. Imaging findings of the left frontal infiltrating glioma predicted the two neoplastic components that were identified upon resection. Tissue examination demonstrated areas of tumor with contrasting histologic and molecular features, including specific IDH1, ATRX, TP53, TERT and CIC mutational profiles, consistent with oligodendroglioma and astrocytoma, respectively. The clinical and radiological course over 17 months from first diagnosis included three surgical resections with slow progression of the astrocytic component, and ultimately chemotherapy and radiation treatments were commenced. Reports of the clinical courses for these rare cases of dual-genotype oligoastrocytomas will inform therapy choices, to optimize benefit while minimizing side effects. The steadily increasing number of cases suggests that the neoplasm might be reconsidered as an official entity by the WHO.

Glioblastoma (GBM) is the deadliest form of brain cancer and recurs uniformly. Despite aggressive treatment with maximal safe surgical resection, adjuvant radiation with temozolomide chemotherapy, and alternating electrical field therapy, median survival for newly diagnosed GBM remains

Background GBM is one of the most deadly cancers and treatment is surgery, followed by radiation (RT) and temozolomide (TMZ) daily during RT followed by cycles of TMZ for select patients.1 New immunotherapies, such as checkpoint inhibition, may benefit patients with GBM. T cell-enabling therapies, in combination with checkpoint inhibition, may improve overall survival (OS). In this study, a novel antigen-specific T cell-generating therapy, INO-5401 (synthetic DNA plasmids encoding for human telomerase [hTERT], Wilms Tumor-1 [WT-1] and prostate specific membrane antigen [PSMA]), plus INO-9012 (synthetic DNA plasmid encoding for IL-12), with the PD-1 checkpoint inhibitor, cemiplimab, was given to patients with newly-diagnosed GBM to evaluate tolerability, immunogenicity and clinical efficacy of the combination. Methods Phase I/II, single arm, two cohort study (A: MGMT Promoter Unmethylated, B: MGMT Promoter Methylated). The primary objective is to evaluate the safety of INO-5401 and INO-9012 followed by EP with CELLECTRA® 2000 in combination with cemiplimab. Secondary objectives include the evaluation of preliminary clinical efficacy and immunogenicity. Treatment is with 9 mg INO-5401 with 1 mg INO-9012 every three weeks (Q3W) for four doses, then Q9W; and cemiplimab (350 mg IV Q3W). RT is given as 40 Gy over three weeks; TMZ is given concurrent with radiation (Cohorts A and B), followed by maintenance TMZ (Cohort B). Results 52 patients were enrolled onto this study; 32 in Cohort A and 20 in Cohort B. 18 were women (35%) and 47 were white (90%). The median age was 60 years (range 19-78 years). The most common Grade ≥3 adverse events were elevations in alanine or aspartate aminotransferase (ALT/AST; 5 patients), and tumor inflammation/edema (5 patients); there was one Grade 5 unrelated event of urosepsis. The only related SAE reported in more than one patient was pyrexia. 22 patients (42%) reported immune-related AEs, with the most common being elevations in ALT or AST (8 patients), and were reported most commonly within the first nine weeks of treatment. The safety profile was consistent with that of patients with GBM and of checkpoint inhibitors. ELISpot assessments performed to date demonstrated the majority of patients have T cell responses to INO-5401. PFS6 was 75% (95% CI 56.6, 88.5) in Cohort A (preliminary; Cohort B pending). Conclusions INO-5401 + INO-9012 with cemiplimab has an acceptable safety profile, is immunogenic and is potentially efficacious in patients with newly-diagnosed GBM. This combination is promising; survival results will be updated next year. Trial Registration NCT03491683. Ethics Approval This study was approved by New York University institution’s Ethics Board; approval number i17-00764. References Stupp R, et al. (2009). Lancet Oncology 10(5): 459–466.

Background Plasma cell-free DNA (cfDNA) concentration is lower in glioblastoma (GBM) compared to other solid tumors, which can lead to low circulating tumor DNA (ctDNA) detection. In this study, we investigated the relationship between multimodality magnetic resonance imaging (MRI) and histopathologic features with plasma cfDNA concentration and ctDNA detection in patients with treatment-naive GBM. Methods We analyzed plasma cfDNA concentration, MRI scans, and tumor histopathology from 42 adult patients with newly diagnosed GBM. Linear regression analysis was used to examine the relationship of plasma cfDNA concentration before surgery to imaging and histopathologic characteristics. In a subset of patients, imaging and histopathologic metrics were also compared between patients with and without a detected tumor somatic mutation. Results Tumor volume with elevated (>1.5 times contralateral white matter) rate transfer constant (Kep, a surrogate of blood–brain barrier [BBB] permeability) was independently associated with plasma cfDNA concentration (P = .001). Histopathologic characteristics independently associated with plasma cfDNA concentration included CD68+ macrophage density (P = .01) and size of tumor vessels (P = .01). Patients with higher (grade ≥3) perivascular CD68+ macrophage density had lower volume transfer constant (Ktrans, P = .01) compared to those with lower perivascular CD68+ macrophage density. Detection of at least 1 somatic mutation in plasma cfDNA was associated with significantly lower perivascular CD68+ macrophages (P = .01). Conclusions Metrics of BBB disruption and quantity and distribution of tumor-associated macrophages are associated with plasma cfDNA concentration and ctDNA detection in GBM patients. These findings represent an important step in understanding the factors that determine plasma cfDNA concentration and ctDNA detection.

BACKGROUND This study builds on the results of the University of Pennsylvania sponsored phase I study of a single peripheral infusion of chimeric antigen receptor (CAR) T cells targeting epidermal growth factor receptor variant III (EGFRvIII) in recurrent glioblastoma (GBM) (NCT02209376). A dose of 5x108 CART-EGFRvIII cells was safe, and the cells were able to expand in the host and reach the GBM tumor in the brain. In addition, there was no cross-reactivity of CART-EGFRvIII cells with wild-type EGFR normally expressed by human tissues. Some patients required tumor resection after CAR T cell infusion. In situ evaluation of the tumor microenvironment demonstrated increased and robust expression of inhibitory molecules, such as programmed death-ligand 1 (PD-L1), compared to pre–CART-EGFRvIII tumor specimens. Therefore, we hypothesized that using a combination of CART-EGFRvIII cells and a PD-1 inhibitor would improve the outcome of the treatment. METHODS This single-center study (NCT03726515) has a single-arm, open-label, phase 1 design and will enroll 7 patients with newly diagnosed, O6-methylguanine-methyltransferase (MGMT)-unmethylated, EGFRvIII+ GBM. Following maximal safe tumor resection, patients receive a short course of adjuvant radiation with a total dose of 40 Gy administered in 15 fractions. Peripheral IV infusions of 2x108 CART-EGFRvIII cells and 200mg pembrolizumab begin 2–3 weeks after completing radiation therapy. Thereafter, subjects receive CART-EGFRvIII cells + pembrolizumab in 3-week cycles for up to 3 infusions of CART-EGFRvIII cells and 4 infusions of pembrolizumab. The primary endpoint of the study is the safety and tolerability of administering multiple infusions of CART-EGFRvIII cells in combination with pembrolizumab, as measured by the occurrence of study-related adverse events. Secondary endpoints include overall survival, progression-free survival, and objective response rate. PROGRESS: At 5 June 2019, 2 patients have been enrolled and treated on study.

In patients with certain hematologic malignancies, the use of autologous T cells genetically modified to express chimeric antigen receptors (CARs) has led to unprecedented clinical responses. Although progress in solid tumors has been elusive, recent clinical studies have demonstrated the feasibility and safety of CAR T-cell therapy for glioblastoma. In addition, despite formidable barriers to T-cell localization and effector function in glioblastoma, signs of efficacy have been observed in select patients. In this review, we begin with a discussion of established obstacles to systemic therapy in glioblastoma and how these may be overcome by CAR T cells. We continue with a summary of previously published CAR T-cell trials in GBM, and end by outlining the key therapeutic challenges associated with the use of CAR T cells in this disease.

PURPOSE Multi-omics data integration captures tumor characteristics at multiple scales [i.e., microscopic (genomics and epigenetics), macroscopic (radiomics), clinical manifestation], provides a more comprehensive assessment of patient’s risk, and facilitates personalized therapies. In this work, we investigated the synergistic value of such multiple data sources for risk stratification and prediction of overall survival in IDH-wildtype glioblastoma tumors. METHODS Quantitative conventional and deep radiomics were extracted from pre-operative multi-parametric structural MRI (T1, T1Gd, T2, T2-FLAIR) of 501 patients with newly diagnosed glioblastoma. 389/501 and 112/501 patients formed our discovery and replication cohorts, respectively. Conventional radiomics were extracted from CaPTk, and deep radiomics from a pre-trained VGG-19 model. Multivariate SVM classification was performed on the discovery cohort to stratify patients in high, medium, and low-risk groups, using recursive feature elimination and 5-fold cross-validation. This model was independently tested on the replication cohort, and a radiomic-based survival prediction index (SPIradiomics) was calculated for each patient. Multi-stage integration of omics data, i.e., clinical (age, gender, extent of resection (EOR)), SPIradiomics, epigenetics (MGMT promoter methylation), and genomics (27 clinically relevant gene mutations via next-generation sequencing (NGS)), was performed using multivariate Cox proportional hazards (Cox-PH) model for stratification of the risk in the replication cohort. RESULTS Cox-PH modeling resulted in a concordance index (c-index) of 0.65 (95% CI:0.6–0.7) for clinical data, 0.67 (95% CI:0.62–0.72) for clinical and epigenetics, 0.70 (95% CI:0.65–0.75) for clinical and radiomics, 0.72 (95% CI:0.68–0.77) for clinical, epigenetics, and radiomics, and 0.75 (95% CI:0.71 – 0.78) for the multi-omics combination of all data; highlighting the added value of each layer of information in prediction of the patient’s risk. CONCLUSION Our results reinforce the synergistic value of integrated diagnostic methods for improving risk assessment of patients with glioblastoma that may pave the path towards a more personalized treatment planning.

BACKGROUND CAN-2409 is a replication-deficient adenovirus that delivers HSV thymidine kinase to cancer cells, resulting in local conversion of orally administered valacyclovir into a toxic metabolite. Previously, a phase 1b/2 clinical trial of CAN-2409 combined with standard-of-care (SOC) demonstrated safety and improved survival in HGG patients. Addition of CAN-2409 to nivolumab has the potential to activate locally recruited lymphocytes and teach them to recognize tumor neoantigens, changing the ‘cold’ immunosuppressive tumor microenvironment, and synergizing with the activity mediated by immune checkpoint inhibitors. This notion is supported by preclinical experiments showing that the combination of CAN-2409 with anti-PD1 therapy was more effective than either treatment alone. METHODS This ongoing phase 1 clinical trial evaluates safety and initial efficacy of CAN-2409 combined with nivolumab and SOC in newly diagnosed HGG. CAN-2409 is injected during neurosurgery into the tumor bed, followed by 14-days of valacyclovir. Radiation starts within 8 (+/-4) days of surgery. Temozolomide is administered to MGMT-methylation positive patients only. Nivolumab is given every 2 weeks, up to 52-weeks. Deep immune profiling studies are ongoing and initial results will be available shortly. RESULTS From February 2019 to March 2021, 41 patients were enrolled and 35 were evaluable for safety from the combination of CAN-2409, nivolumab and SOC: 24 male and 11 female; 34 glioblastoma, 1 diffuse astrocytoma; 33 IDH-wildtype, 2 IDH-mutant; 15 MGMT-methylated, 20 unmethylated. Median age was 62-years (range 28-79), median KPS 90 (range 80-100). With 13 months median follow-up, no unexpected serious adverse events were observed, and 23 patients are still alive. The most frequent possibly related adverse events (>10%) were nausea, fatigue, fever, headache, and increased ALT. CONCLUSIONS The combination of CAN-2409 + nivolumab + SOC was well tolerated. Clinical follow-up and extensive biomarker analyses will provide a better understanding of the therapeutic potential of this approach.

BACKGROUND Preclinical studies have demonstrated that IDH1-mutant (IDHmt) gliomas harbor a BRCAness phenotype with a defect in homologous recombination that confers PARP inhibitor sensitivity. Pamiparib (BeiGene BGB-290) is an effective PARP-trapping PARP inhibitor with demonstrated favorable brain penetration in animal models. METHODS ABTC 1801 is a study examining the safety, pharmacokinetics, and efficacy of the combination of pamiparib with low dose metronomic temozolomide in recurrent IDHmt gliomas. The Phase I component utilized a 3 + 3 design with a target DLT rate ≤ 33%. Pamiparib dose was 60 mg BID and temozolomide dose 20 mg daily, with dose de-escalation levels for anticipated hematological toxicity. RESULTS Seven patients were enrolled on the Phase I portion at dose level 1; one patient was replaced for inadequate dosing secondary to non-compliance. All patients had prior radiotherapy and temozolomide; 4/7 had received multiple lines of alkylator therapy including nitrosoureas. Median age was 45, KPS 90, and number of prior relapses 3. Four patients had anaplastic astrocytoma, 2 anaplastic oligodendroglioma, and 1 glioblastoma. One of 6 patients (16.7%) experienced DLT during the first cycle (grade 3 neutropenia and thrombocytopenia). Two additional patients had grade 2 neutropenia. Two patients remain on study treatment at 12+ and 10+ months, while a third progressed at 10.1 months (PFS-6 43%). Tumor tissue was collected from two patients in the surgical arm. In enhancing and non-enhancing tumors, the mean unbound pamiparib concentrations were 198 and 160 nmol/L (or nmol/kg), respectively, which were > 20-fold the in vitro IC50 for PARP inhibition; mean unbound tumor-to-plasma ratios were 0.65 and 0.38. CONCLUSIONS Phase I results support pamiparib 60 mg BID with temozolomide 20 mg daily as the dosages for the Phase II study. Preliminary Phase 0 data suggest that pamiparib likely achieves sufficient pharmacologically active concentrations in both enhancing and non-enhancing brain tumors.

Background: Glioblastoma (GBM) is the most common malignant brain tumor and carries a dismal prognosis. Attempts to develop biologically targeted therapies are challenging as the blood–brain barrier can limit drugs from reaching their target when administered through conventional (intravenous or oral) routes. Furthermore, systemic toxicity of drugs often limits their therapeutic potential. To circumvent these problems, convection-enhanced delivery (CED) provides direct, targeted, intralesional therapy with a secondary objective to alter the tumor microenvironment from an immunologically “cold” (nonresponsive) to an “inflamed” (immunoresponsive) tumor. Case Description: We report a patient with right occipital recurrent GBM harboring poor prognostic genotypes who was treated with MRI-guided CED of a fusion protein MDNA55 (a targeted toxin directed toward the interleukin-4 receptor). The patient underwent serial anatomical, diffusion, and perfusion MRI scans before initiation of targeted therapy and at 1, 3-month posttherapy. Increased mean diffusivity along with decreased fractional anisotropy and maximum relative cerebral blood volume was noted at follow-up periods relative to baseline. Conclusion: Our findings suggest that diffusion and perfusion MRI techniques may be useful in evaluating early response to CED of MDNA55 in recurrent GBM patients.

Objectives Comparisons of induction chemotherapy (IC) against upfront chemoradiation (CRT) for locally advanced head and neck cancer (LA-HNSCC) have demonstrated no differences except greater toxicity with IC. Effective induction regimens that are less toxic are therefore warranted. To inform future efforts with IC, we present our institutional experience comparing a less toxic IC regimen to CRT. Methods We included patients with LA-HNSCC treated with organ-preservation CRT (+/-induction) between 2008 and 2011. Patients were of age above 18 years, ECOG performance status 0-1, and had minimum 6 months follow-up. IC consisted of 8 weekly cycles of cetuximab, carboplatin, and paclitaxel followed by CRT. The CRT regimen was platinum based, with cetuximab reserved for patients contraindicated to receive platinum. Results Of 118 patients, 24 (20%) received IC and 94 (80%) received CRT. Median follow-up was 17 (IC) and 19 (CRT) months (P=0.05). There were no differences in toxicity between the groups. IC patients were more likely male, with more advanced tumor and nodal stage. Even when controlling for these factors, IC was still associated with worse locoregional control (HR=3.6, P=0.02), distant metastasis-free survival (HR=5.3, P=0.02), and overall survival (HR=5.1, P Conclusions IC patients had greater disease burden than those receiving CRT. IC was well tolerated, but with significant rates of locoregional and systemic failures. Given the retrospective nature of the study, our findings are not meant to be definitive or conclusive, but rather suggestive in directing future efforts with IC. For now, we favor CRT as the standard option for treatment of inoperable LA-HNSCC.

BACKGROUND Immune checkpoint inhibitors (ICIs) are not uniformly effective in glioblastoma treatment. Immunogenomic determinants may identify patients who are most likely to benefit from these therapies. Therefore, we compared the immunogenomic phenotype of a responder to combination anti-LAG-3 and anti-PD-1 therapy to non-responders. METHODS We performed T cell receptor (TCR) sequencing and gene expression analysis on pre-treatment, post-chemoradiation, and post-immunotherapy tumor specimens of glioblastoma patients treated with anti-LAG3 in combination with anti-PD-1 after first recurrence (NCT02658981, ongoing). We evaluated T cell clonotypes and immunophenotype of serially collected peripheral blood mononuclear cells (PBMCs) during treatment using multi-parametric flow cytometry. RESULTS To date, six patients have been enrolled in the initial anti-LAG-3 and anti-PD-1 cohort. One patient demonstrated complete response, one had stable disease, and four had progressive disease by radiographic evaluation. The responder demonstrated substantially higher TCR clonality in the resected tumor at initial diagnosis compared to non-responders (mean 0.028 vs. 0.005). Shared tumor infiltrating clonotypes with pre-immunotherapy PBMCs exhibited an increase in frequency from initial resection (6.8%) to resection at recurrence (20%). The responder’s tumor at initial resection exhibited increased gene signatures of PD1low CD8+ T cells, chemokine signaling, and interferon gamma pathways. On PBMC phenotypic analysis, the responder demonstrated significantly higher percentages of CD137+ CD8+T cells (median 8.38% vs 3.24%, p=0.02) and lower percentages of Foxp3+CD137+ CD4+T cells compared to non-responders (median 18.5% vs. 38.5%, p=0.006). Interestingly, dynamic analysis of PBMCs showed that the responder demonstrated a lower percentage of PD1+ CD8+ T cells pre-immunotherapy (median 2.5% vs.12.4%, p=0.002), with persistent decrease over the course of treatment while non-responders showed no consistent pattern. CONCLUSION Our preliminary results demonstrate significant differences in tumor and peripheral blood immunogenomic characteristics between responder and non-responders to anti-LAG3 and anti-PD-1 therapy. These immunogenomic characteristics may help stratify patients’ response to combination ICIs.

Purpose: The clinical utility of plasma cell-free DNA (cfDNA) has not been assessed prospectively in patients with glioblastoma (GBM). We aimed to determine the prognostic impact of plasma cfDNA in GBM, as well as its role as a surrogate of tumor burden and substrate for next-generation sequencing (NGS). Experimental Design: We conducted a prospective cohort study of 42 patients with newly diagnosed GBM. Plasma cfDNA was quantified at baseline prior to initial tumor resection and longitudinally during chemoradiotherapy. Plasma cfDNA was assessed for its association with progression-free survival (PFS) and overall survival (OS), correlated with radiographic tumor burden, and subjected to a targeted NGS panel. Results: Prior to initial surgery, GBM patients had higher plasma cfDNA concentration than age-matched healthy controls (mean 13.4 vs. 6.7 ng/mL, P < 0.001). Plasma cfDNA concentration was correlated with radiographic tumor burden on patients' first post-radiation magnetic resonance imaging scan (ρ = 0.77, P = 0.003) and tended to rise prior to or concurrently with radiographic tumor progression. Preoperative plasma cfDNA concentration above the mean (>13.4 ng/mL) was associated with inferior PFS (median 4.9 vs. 9.5 months, P = 0.038). Detection of ≥1 somatic mutation in plasma cfDNA occurred in 55% of patients and was associated with nonstatistically significant decreases in PFS (median 6.0 vs. 8.7 months, P = 0.093) and OS (median 5.5 vs. 9.2 months, P = 0.053). Conclusions: Plasma cfDNA may be an effective prognostic tool and surrogate of tumor burden in newly diagnosed GBM. Detection of somatic alterations in plasma is feasible when samples are obtained prior to initial surgical resection.

BACKGROUND Imaging of glioblastoma patients after maximal safe resection and chemoradiation commonly demonstrates new enhancements that raise concerns about tumor progression. However, in 30% to 50% of patients, these enhancements primarily represent the effects of treatment, or pseudo-progression (PsP). We hypothesize that quantitative machine learning analysis of clinically acquired multiparametric magnetic resonance imaging (mpMRI) can identify subvisual imaging characteristics to provide robust, noninvasive imaging signatures that can distinguish true progression (TP) from PsP. METHODS We evaluated independent discovery (n = 40) and replication (n = 23) cohorts of glioblastoma patients who underwent second resection due to progressive radiographic changes suspicious for recurrence. Deep learning and conventional feature extraction methods were used to extract quantitative characteristics from the mpMRI scans. Multivariate analysis of these features revealed radiophenotypic signatures distinguishing among TP, PsP, and mixed response that compared with similar categories blindly defined by board-certified neuropathologists. Additionally, interinstitutional validation was performed on 20 new patients. RESULTS Patients who demonstrate TP on neuropathology are significantly different (P

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults and carries a dismal prognosis. Significant challenges in the care of patients with GBM include marked vascular heterogeneity and arteriovenous (AV) shunting, which results in tumor hypoxia and inadequate delivery of systemic treatments to reach tumor cells. In this study, we investigated the utility of different MR perfusion techniques to detect and quantify arteriovenous (AV) shunting and tumor hypoxia in patients with GBM. Macrovascular shunting was present in 33% of subjects, with the degree of shunting ranging from (37–60%) using arterial spin labeling perfusion. Among the dynamic susceptibility contrast-enhanced perfusion curve features, there were a strong negative correlation between hypoxia score, DSC perfusion curve recovery slope (r = −0.72, P = 0.018) and angle (r = −0.73, P = 0.015). The results of this study support the possibility of using arterial spin labeling and pattern analysis of dynamic susceptibility contrast-enhanced MR Imaging for evaluation of arteriovenous shunting and tumor hypoxia in glioblastoma.

EGFRvIII targeted chimeric antigen receptor T (CAR-T) cell therapy has recently been reported for treating glioblastomas (GBMs); however, physiology-based MRI parameters have not been evaluated in this setting. Ten patients underwent multiparametric MRI at baseline, 1, 2 and 3 months after CAR-T therapy. Logistic regression model derived progression probabilities (PP) using imaging parameters were used to assess treatment response. Four lesions from “early surgery” group demonstrated high PP at baseline suggestive of progression, which was confirmed histologically. Out of eight lesions from remaining six patients, three lesions with low PP at baseline remained stable. Two lesions with high PP at baseline were associated with large decreases in PP reflecting treatment response, whereas other two lesions with high PP at baseline continued to demonstrate progression. One patient didn’t have baseline data but demonstrated progression on follow-up. Our findings indicate that multiparametric MRI may be helpful in monitoring CAR-T related early therapeutic changes in GBM patients.

PURPOSE Differentiation of true tumor progression from pseudoprogression (PsP) is a major unmet need in patients with glioblastoma (GBM). [18F]Fluciclovine is a synthetic amino acid PET radiotracer that is FDA approved in the setting of biochemical recurrence in prostate cancer. The aim of this study was to assess the value of [18F]Fluciclovine PET in differentiation of true tumor progression and PsP in post-treatment of glioblastoma. METHODS 15 patients with GBM with new contrast-enhancing lesions or lesions showing increased enhancement (>25% increase) on standard MRI after completion of radiation underwent 60-minutes dynamic [18F]Fluciclovine PET imaging. Patients subsequently (within 1 week) underwent resection of the enhancing lesion and the tumor percentage vs treatment-related changes were quantified on histopathology. Patients were considered true tumor progression if tumor represented ≥ 50% of the resected specimen and considered PsP if treatment-related changes represented ≥70% of the resected specimen. Summed 30- to 40-minute post-injection PET images were used to measure SUVpeak, SUVmax, and 50% threshold SUVmean. RESULTS 10 patients with true tumor progression and 5 patients with PsP were included. Patients who demonstrated true tumor progression had significantly higher SUVpeak compared to patients with PsP (5.3±1.4 vs 3.1± 0.9, p=0.002, AUC=0.92, p DISCUSSION Our preliminary results indicated that [18F]Fluciclovine PET imaging can accurately differentiate true tumor progression from PsP. Further studies are required to confirm these promising early results and determine the optimal criteria for interpreting [18F]Fluciclovine PET to distinguish PsP from true tumor progression.

Quantitative 3'-deoxy-3'-18F-fluorothymidine (18F-FLT) PET has potential as a noninvasive tumor biomarker for the objective assessment of response to treatment. To guide interpretation of these quantitative data, we evaluated the repeatability of 18F-FLT PET as part of a multicenter trial involving patients with high-grade glioma. Methods:18F-FLT PET was performed on 10 patients with recurrent high-grade glioma at 5 different institutions within the Adult Brain Tumor Consortium trial ABTC1101. Data were acquired according to a double baseline protocol in which PET examinations were repeated within 2 d of each other with no intervening treatment. On each of the 2 imaging days, dedicated brain PET was performed at 2 time points, 1 and 3 h after 18F-FLT administration. Tumor SUVs and related parameters were measured at a central laboratory using various volumes of interest: isocontour at 30% of the maximum pixel (SUVmean_30%), gradient-based segmentation (SUVmean_gradient), the maximum pixel (SUVmax), and a 1-mL sphere at the region of highest uptake (SUVpeak). Repeatability coefficients (RCs) were calculated from the relative differences between corresponding SUV measurements obtained on the 2 d. Results: RCs for tumor SUVs were 22.5% (SUVmean_30%), 23.8% (SUVmean_gradient), 23.2% (SUVmax), and 18.5% (SUVpeak) at 1 h after injection. Corresponding data at 3 h were 22.4%, 25.0%, 27.3%, and 23.6%. Normalizing the tumor SUV data with reference to a background region improved repeatability, and the most stable parameter was the tumor-to-background ratio derived using SUVpeak (RC, 16.5%). Conclusion: SUV quantification of 18F-FLT uptake in glioma had an RC in the range of 18%-24% when imaging began 1 h after 18F-FLT administration. The volume-of-interest methodology had a small but not negligible influence on repeatability, with the best performance obtained using SUVpeak Although changes in 18F-FLT SUV after treatment cannot be directly interpreted as a change in tumor proliferation, we have established ranges beyond which SUV differences are likely due to legitimate biologic effects.

The purpose of this pilot study was to determine whether blood-borne microvesicles from newly diagnosed glioblastoma patients could be used as biomarkers. We collected 2.8 mL blood from 16 post-operative patients at the time that they were being simulated for chemoradiation therapy (radiation with concurrent temozolomide). Two additional samples were collected during chemoradiation therapy and a final sample was collected at the end of chemoradiation therapy. Patients continued with the therapy suggested by their physicians, based on tumor conference consensus and were followed for recurrence and overall survival. Microvesicles were isolated using serial centrifugation and stained for surface markers (Annexin V for phosphotidyl serine, CD41 for platelets, anti-EGFR for tumor cells, and CD235 for red blood cells). Flow cytometry analysis was performed. Our findings provide initial evidence that increases in Annexin V positive microvesicle levels during chemoradiation therapy are associated with earlier recurrence and shorter overall survival in newly diagnosed glioblastoma patients. The effect is dramatic, with over a four-fold increase in the hazard ratio for an individual at the 75th versus the 25th percentile. Moreover the pattern of Annexin V positive microvesicles remain significant after adjustment for confounding clinical variables that have previously been shown to be prognostic for recurrence and survival. Inclusion of neutrophil levels at the start of chemoradiation therapy in the model yielded the largest attenuation of the observed association. Further studies will be needed to verify and further investigate the association between these two entities.

BACKGROUND AND PURPOSE: Early assessment of treatment response is critical in patients with glioblastomas. A combination of DTI and DSC perfusion imaging parameters was evaluated to distinguish glioblastomas with true progression from mixed response and pseudoprogression. MATERIALS AND METHODS: Forty-one patients with glioblastomas exhibiting enhancing lesions within 6 months after completion of chemoradiation therapy were retrospectively studied. All patients underwent surgery after MR imaging and were histologically classified as having true progression (>75% tumor), mixed response (25%–75% tumor), or pseudoprogression (

2514 Background: Novel T cell-enabling therapies, in combination with checkpoint inhibition, may improve OS in GBM. INO-5401 (synthetic DNA plasmids encoding for hTERT, WT-1 and PSMA), plus INO-9012 (synthetic DNA plasmid encoding IL-12), with the PD-1 checkpoint inhibitor cemiplimab, is given to patients with newly-diagnosed GBM to evaluate tolerability, efficacy and immunogenicity of the combination. Methods: Phase I/II, single arm, 2 cohort study (A: MGMT unmethylated, B: MGMT methylated). The primary endpoint is safety; efficacy and immunogenicity are secondary. Nine mg INO-5401 plus 1 mg INO-9012 (every 3 weeks for 4 doses, then Q9W) is given with EP by CELLECTRA 2000 with cemiplimab (350 mg IV Q3W). RT is given as 40 Gy over 3 weeks. TMZ is given with radiation (all patients), followed by maintenance (Cohort B only). Results: Fifty two subjects were enrolled: 32 in Cohort A; 20 in Cohort B. 35% women and 90% white. Median age 60 years (range 19-78 years). Common Grade ≥3 AEs reported were: platelet count decreased (11.5%), tumor inflammation (7.7%), seizure (7.7%), ALT increased (7.7%), lymphocyte count decreased (7.7.%). One Grade 5 unrelated event of urosepsis was reported. Of 69 SAEs reported there was only 1 related to the combination therapy, Grade 1 pyrexia. 48% of subjects reported irAEs, most frequently ALT increased (9.6%), AST increased (7.7%), diarrhea (7.7%), pyrexia (7.7%) and tumor inflammation (7.7%). 71% of the reported SAEs and irAEs occurred within the first 12 weeks of treatment. OS at 12 months was 84.4% (95% CI 67.2, 94.7) in Cohort A; Cohort B will be presented at ASCO. ELISpot assessments demonstrated T cell responses to INO-5401. Flow cytometry demonstrated evidence of activated INO-5401-specific CD8+T cells with lytic potential (CD38+Prf+GrzA+) when compared with baseline, post-treatment in the majority of patients assayed. Conclusions: INO-5401 + INO-9012 in combination with cemiplimab and RT/TMZ has an acceptable safety profile, is immunogenic and may show a survival advantage in patients with newly-diagnosed GBM. OS18 data will be presented later this year. Clinical trial information: NCT03491683 .

2508 Background: Due to significant interpatient heterogeneity, survival outcomes vary widely in patients with GBM. Novel prognostic biomarkers are needed. We aimed to determine the prognostic impact of baseline plasma cfDNA concentration in patients with GBM. Methods: We analyzed 84 patients with newly diagnosed GBM and at least 7 months of follow-up time. The first 41 patients comprised a previously published derivation cohort (Bagley, Clin Cancer Res 2020). The subsequent 43 patients served as an independent validation cohort. cfDNA was extracted from plasma collected prior to initial surgical resection and quantified by qPCR for a 115 bp amplicon of the human ALU repeat element. Receiver operating characteristic (ROC) curve analysis was used in the derivation cohort to (1) assess the accuracy of plasma cfDNA concentration for predicting progression-free survival status at 7 months (PFS-7), a landmark based on the median PFS for newly diagnosed GBM (Stupp, N Engl J Med 2005), and (2) derive the optimal cutoff for dichotomizing patients into high- and low-cfDNA groups. In the validation cohort, logistic regression was used to measure the association of plasma cfDNA concentration (high vs. low) with PFS-7, adjusted for age, isocitrate dehydrogenase ( IDH) 1/2 mutational status, 0-6-methylguanine-methyltransferase ( MGMT) methylation, extent of resection, and performance status. Multivariate Cox regression was used for overall survival (OS) analysis. Results: In the derivation cohort, the optimal cutoff for plasma cfDNA was 25.0 ng/mL (area under the curve [AUC] = 0.663), with inferior PFS and OS in patients with cfDNA above this cutoff (PFS, median 4.9 vs. 9.5 months, log-rank p = 0.001; OS, median 8.5 vs. 15.5 months, log-rank p = 0.03). In the validation cohort, baseline plasma cfDNA concentration over the cutoff was independently associated with a lower likelihood of being alive and progression-free at 7 months (adjusted OR 0.13, 95% CI 0.02 – 0.75, p = 0.02). OS was also worse in in the validation cohort in patients with high plasma cfDNA (adjusted HR 3.0, 95% CI 1.1 – 8.0, p = 0.03). Conclusions: In patients with newly diagnosed GBM, high baseline plasma cfDNA concentration is associated with worse survival outcomes independent of other prognostic factors. Further validation in a larger, multicenter study is warranted.

BACKGROUND Liquid biopsy has been not been widely utilized in patients with glioblastoma (GBM) compared to other solid tumors. However, the clinical utility of plasma cell-free DNA (cfDNA) in GBM has not been assessed prospectively or at the time of initial diagnosis. METHODS We conducted a prospective cohort study of patients with newly diagnosed GBM. Whole blood was collected in Streck® tubes at baseline prior to initial surgical resection and longitudinally during the course of adjuvant chemoradiotherapy. Plasma cfDNA concentration (ng/mL) was quantified by qPCR for a 115 bp amplicon of the human ALU repeat element, correlated with radiographic tumor burden by volumetry at multiple time points using Spearman rank correlation, and assessed for its impact on progression-free (PFS) and overall survival (OS) by Cox regression. RESULTS Prior to initial resection, GBM patients (N=42) had higher plasma cfDNA concentration compared to age-matched healthy controls (N=42) (mean 13.43 vs. 6.70 ng/mL, p< 0.001). Plasma cfDNA concentration was correlated with radiographic tumor burden on subjects’ first post-radiation MRI scan (r=0.77, p=0.003) and tended to rise prior to or concurrently with radiographic tumor progression. Pre-operative plasma cfDNA concentration above the mean (>13.4 ng/mL) was associated with inferior PFS (median 4.9 vs. 9.5 months, p=0.038) and OS (median 8.9 vs. 14.8 months, p=0.078). The impact on PFS persisted after adjusting for age, extent of resection, performance status, MGMT promoter methylation, and IDH1/2 mutational status (HR 2.48, 95% CI 1.1–6.1, p=0.046). CONCLUSIONS Plasma cfDNA may be an effective prognostic tool and noninvasive surrogate of tumor burden in newly diagnosed GBM. Tumor tissue samples from our cohort have been subjected to targeted next generation sequencing (NGS), and baseline plasma samples have been sent to Guardant Health for NGS. Plasma NGS results and concordance with matched tissue NGS will be included at time of presentation.

BACKGROUND Oligodendroglioma is a rare primary brain tumor characterized by mutation in the IDH1/IDH2 genes and codeletion of chromosomes 1p and 19q. Although median overall survival extends beyond 10 years for patients with oligodendroglioma who receive adjuvant radiation and alkylating chemotherapy, the disease uniformly relapses and has no other effective treatments. The CIC gene, which encodes a high-mobility group box transcriptional repressor, is mutated in about 70% of oligodendrogliomas and is associated with worse prognosis and overexpression of cyclin D1 (CCND1). Cyclin D1 assembles with the cyclin-dependent kinases CDK4 and CDK6 to cause phosphorylation of Rb protein and subsequent cell cycle progression from the G1 to S phase. Therapeutic inhibition of CDK4/6 activity, which leads to Rb dephosphorylation and cell cycle arrest, has revolutionized the care of breast cancer. The current phase 2 study will investigate the efficacy and safety of abemaciclib, a selective and potent small molecule inhibitor of CDK4 and CDK6 with significant brain-brain barrier penetration, in patients with 1p/19q codeleted oligodendroglioma that has recurred after standard radiation and alkylating chemotherapy. METHODS This protocol (NCT03969706) has a single-arm, open-label, single-stage phase 2 design. Subjects will be treated with abemaciclib 200mg tablet twice daily on 28-day cycles until disease progression or unacceptable toxicity. Tumor response will be assessed according to modified Response Assessment in Neuro-Oncology (mRANO) criteria. The primary objective of the study is to determine the efficacy of abemaciclib for recurrent oligodendroglioma. The primary endpoint is the progression-free survival status of the subject at 6 months after enrollment (PFS-6). The alternative hypothesis is that the proportion of subjects without an event at 6 months will be ³85%. We will test this hypothesis against a null hypothesis of PFS-6 = 50%. With enrollment of 10 planned subjects, the power to detect this difference is 82% (one-sided alpha = 0.05).

INTRODUCTION: We sought to determine which therapeutically targetable immune checkpoints, costimulatory signals, and other tumor microenvironment (TME) factors are independently associated with immune cytolytic activity (CYT), a gene expression signature of activated effector T cells, in human glioblastoma (GBM). METHODS: GlioVis was accessed for RNA-seq data from The Cancer Genome Atlas (TCGA). For subjects with treatment-naïve, primary GBM, we quantified mRNA expression of 28 therapeutically targetable TME factors. CYT (geometric mean of GZMA and PRF1 expression) was calculated for each tumor. Multiple linear regression was performed to determine the relationship between the dependent variable (CYT) and mRNA expression of each of the 28 factors. Variables associated with CYT in multivariate analysis were subsequently evaluated for this association in an independent cohort of newly diagnosed GBMs from the Chinese Glioma Cooperative Group (CGCG). RESULTS: 109 TCGA tumors were analyzed. The final multiple linear regression model included the following variables, each positively associated with CYT except VEGF-A (negative association): CSF-1 (p=0.003), CD137 (p=0.042), VEGF-A (p

AZD1775 is an oral small molecular inhibitor of the G2/M checkpoint regulator Wee1. The Adult Brain Tumor Consortium 1202 trial (NCT01849146) is a phase I, open label, multicenter dose-finding study of AZD1775 in combination with standard RT and TMZ followed by an IDD study for patients undergoing surgery for recurrent GBM. Dose of AZD1775 was increased in a 3 + 3 design M-F during concurrent RT/TMZ and x 5d/28d cycle with adjuvant TMZ in separate cohorts. A combination cohort with both concurrent and adjuvant AZD1775 at MTD and analysis of PK/PD and IDD at MTD in patients undergoing surgery for recurrent GBM followed. MTD was 200 mg for concurrent with 2/6 patients experiencing DLTs (grade 4 neutropenia, grade 3 ALT elevation). MTD for the adjuvant cohort was 425 mg with 1/6 patients experiencing DLT (grade 4 decrease in ANC). 6/12 patients experienced DLTs when cohorts were combined, however, five during the concurrent phase. Three patients had grade ≥3 ALT/AST elevation, one had grade 3 afib, and one had grade 4 neutropenia/thrombocytopenia, grade 3 dehydration/fatigue/muscle weakness. A sixth patient had grade 4 neutropenia in the first adjuvant cycle. Following amendment, an additional 6 patients were enrolled with 150 mg (concurrent) and 425 mg (adjuvant) combination and are in the observation period with one DLT currently. Drug concentration in contrast enhancing and non-enhancing brain tumor was 4–8 x and 0.5–2.6 x greater than plasma, respectively for patients on IDD portion. CONCLUSIONS: AZD1775 in combination with RT/TMZ at 200 mg qd M-F with concurrent RT/TMZ and 425 mg qd x 5d/28d cycle in combination with adjuvant TMZ had unacceptable DLT rate in the concurrent phase. A cohort with 150 mg concurrent/425 mg adjuvant has competed accrual with acceptable rates of toxicity currently in observation. AZD1775 has good penetration to non-enhancing and enhancing tumor areas.

BACKGROUND: Distinguishing between radiographic pseudoprogression and true tumor progression is challenging in patients with GBM. Recent data suggests that plasma cfDNA concentration may serve as a viable surrogate for tumor burden in other malignancies. We performed a pilot study to determine the feasibility of detecting cfDNA in patients with newly diagnosed GBM and explored its correlation with radiographic tumor burden and other relevant clinical variables. METHODS: We collected blood in Streck cfDNA tubes from patients with radiographically suspected high-grade glioma prior to planned initial surgical resection. Plasma was isolated using a 3-step centrifugation protocol. cfDNA was extracted from using a QIAamp Circulating Nucleic Acid Kit. cfDNA concentration (ng DNA/mL) was determined by quantitative real-time PCR (qPCR) for the ALU repeat element. Tumor burden was defined as the sum of products of diameters (SPD) of target enhancing lesions plus the SPD of the T2 FLAIR signal abnormality on preoperative MRI. RESULTS: 22 preoperative patients were enrolled and diagnosed histopathologically with GBM. The median cfDNA concentration was 10.9 ng/mL (IQR 7.2–23.6, range 0.48–37.6). There was a significant correlation between radiographic tumor burden and cfDNA concentration (Spearmans rho = 0.46, p = 0.03). In a multiple linear regression model, cfDNA concentration remained significantly associated with radiographic tumor burden (beta coefficient 1.87, p=0.03) after adjusting for age, sex, tumor Ki-67 proliferation rate, weight, and glomerular filtration rate (GFR). GFR was also independently (negatively) associated with cfDNA concentration. CONCLUSIONS: In this small pilot study, we demonstrated that plasma cfDNA is easily detected and quantified in patients with newly diagnosed GBM prior to initial surgical resection. In addition, plasma cfDNA concentration was independently associated with radiographic tumor burden. A prospective, longitudinal study monitoring cfDNA dynamics during standard treatment for GBM, including gold standard tissue correlates for tumor progression vs. pseudoprogression, is ongoing at our institution.

We conducted a first-in-human study of intravenous delivery of a single dose of autologous T cells redirected to the epidermal growth factor receptor variant III (EGFRvIII) mutation by a chimeric antigen receptor (CAR). We report our findings on the first 10 recurrent glioblastoma (GBM) patients treated. We found that manufacturing and infusion of CAR-modified T cell (CART)-EGFRvIII cells are feasible and safe, without evidence of off-tumor toxicity or cytokine release syndrome. One patient has had residual stable disease for over 18 months of follow-up. All patients demonstrated detectable transient expansion of CART-EGFRvIII cells in peripheral blood. Seven patients had post-CART-EGFRvIII surgical intervention, which allowed for tissue-specific analysis of CART-EGFRvIII trafficking to the tumor, phenotyping of tumor-infiltrating T cells and the tumor microenvironment in situ, and analysis of post-therapy EGFRvIII target antigen expression. Imaging findings after CART immunotherapy were complex to interpret, further reinforcing the need for pathologic sampling in infused patients. We found trafficking of CART-EGFRvIII cells to regions of active GBM, with antigen decrease in five of these seven patients. In situ evaluation of the tumor environment demonstrated increased and robust expression of inhibitory molecules and infiltration by regulatory T cells after CART-EGFRvIII infusion, compared to pre-CART-EGFRvIII infusion tumor specimens. Our initial experience with CAR T cells in recurrent GBM suggests that although intravenous infusion results in on-target activity in the brain, overcoming the adaptive changes in the local tumor microenvironment and addressing the antigen heterogeneity may improve the efficacy of EGFRvIII-directed strategies in GBM.

Background Mibefradil (MIB), previously approved for treatment of hypertension, is a selective T-type calcium channel blocker with preclinical activity in high-grade gliomas (HGGs). To exploit its presumed mechanism of impacting cell cycle activity (G1 arrest), we designed a phase I study to determine safety and the maximum tolerated dose (MTD) of MIB when given sequentially with temozolomide (TMZ) in recurrent (r)HGG. Methods Adult patients with rHGG ≥3 months from TMZ for initial therapy received MIB in 4 daily doses (q.i.d.) for 7 days followed by standard TMZ at 150-200 mg/m2 for 5 days per 28-day cycle. MIB dose escalation followed a modified 3 + 3 design, with an extension cohort of 10 patients at MTD who underwent 3'-deoxy-3'-18F-fluorothymidine (18F-FLT) PET imaging, to image proliferation before and after 7 days of MIB. Results Twenty-seven patients were enrolled (20 World Health Organization grade IV, 7 grade III; median age 50 y; median KPS 90). The MTD of MIB was 87.5 mg p.o. q.i.d. Dose-limiting toxicities were elevation of alanine aminotransferase/aspartate aminotransferase (grade 3) and sinus bradycardia. The steady-state maximum plasma concentration of MIB at the MTD was 1693 ± 287 ng/mL (mean ± SD). 18F-FLT PET imaging showed a significant decline in standardized uptake value (SUV) signal in 2 of 10 patients after 7 days of treatment with MIB. Conclusions MIB followed by TMZ was well tolerated in rHGG patients at the MTD. The lack of toxicity and presence of some responses in this selected patient population suggest that this regimen warrants further investigation.

2027 Background: Hypoxia inducible factor 2-alpha (HIF2a) mediates cellular responses to hypoxia and is overexpressed in GBM. PT2385 is an oral HIF2a inhibitor with in vivo activity against GBM. Methods: A two-stage single-arm open-label phase II study of adults with first recurrent GBM following chemoradiation with measurable disease was conducted through the Adult Brain Tumor Consortium. PT2385 was administered at the phase II dose (800 mg b.i.d.). The primary outcome was objective radiographic response (CR+PR); secondary outcomes were safety and survival. Exploratory objectives included PK (day 15 Cmin), PD, and pH-weighted amine-CEST MRI to quantify tumor acidity at baseline and explore associations with drug response. Stage 1 enrolled 24 patients with early stoppage for ≤1 response. Results: Of the 24 patients, mean age was 61±11 years, median KPS 80, MGMT promoter methylated in 46%. PT2385 was well tolerated. Grade ≥3 drug-related AEs were hypoxia (n = 2), anemia (1), hyperglycemia (1), hyponatremia (2) and lymphopenia (2). No objective radiographic responses were observed; median PFS was 1.8 months (95%CI 1.6-3.1). Drug exposure varied widely (Table) and did not differ by corticosteroid use (p = 0.12), antiepileptics (p = 0.09), or sex (p = 0.37). Patients with high systemic exposure had significantly longer PFS (6.7 vs 1.8 months, 0.009). Non-enhancing infiltrative disease with high acidity gave rise to recurrence. Baseline acidity correlated significantly with treatment duration (R2= 0.49, p = 0.017). Conclusions: Drug exposure to PT2385 was variable. Signals of activity were observed in GBM patients with high systemic exposure and acidic (e.g. hypoxic) lesions on baseline imaging. A second-generation HIF2a inhibitor is being studied. Clinical trial information: NCT03216499. [Table: see text]

2017 Background: Preclinical GBM data targeting the checkpoint molecules Lag-3 and CD137 have shown promising anti-tumor immune response with resultant improved survival when combined with anti-PD-1. Here we report our experience from a multi-arm safety study in patients with recurrent GBM treated with anti-Lag-3 and anti-CD137. Methods: The Adult Brain Tumor Consortium (ABTC) 1501 trial is a phase I, open label, multicenter, multi-arm dose-finding/safety study of anti-LAG-3 (BMS-986016) or anti-CD137 (BMS-663513) alone and in combination with anti-PD-1 in patients at first recurrence of GBM. The primary objective is to define MTD for the mono and combinational treatment. The major secondary objective is to explore for a signal in efficacy. The key inclusion criteria are adults, first recurrence of GBM following RT+TMZ, TLC≥1000/ul, KPS≥ 60%, stable corticosteroid regimen, measurable disease, and written informed consent. Sequential allocation was used for the treatment assignment at starting dose of 80mg for anti-LAG-3 and 8mg for anti-CD137. Anti-PD-1was given at a flat dose of 240 mg in the combination treatment arms. The 3+3 design is used for the dose finding with a target DLT rate < 33%. Results: to date 44 patients were enrolled into the trial with median age at 57, median KPS at 90. Median treatment cycle was 3 and 39% tumors were MGMT methylated. The highest safe dose for Anti-LAG-3 alone is 800 mg without a DLT. The safe dose for anti-CD137 alone arm is 8mg with 1 DLT, and 2 grade 3 elevated serum ALT at end of cycle 2. Combination arms of Anti-LAG-3 +anti-PD-1 (160 mg/240mg as the highest dose combination) had one DLT (hypertension) and no toxicities were seen in the combination arm of Anti-CD137+Anti-PD-1 (3 mg/240 mg). mOS was 14 months for anti-CD137 alone, 8 months for Anti-Lag-3, and 7 months for Anti-Lag-3 + Anti-PD-1. Correlative data will be discussed. Conclusions: The trial is ongoing. The RP2D is 800mg for anti-LAG-3 as a monotherapy and 8mg for anti-CD137. For the combination arms, 160 mg of Anti-LAG-3 and 240 mg of anti-PD-1 and 3 mg of anti-CD137 and 240 mg antiPD-1 were the RP2D. Clinical trial information: NCT02658981.

BACKGROUND: Hypoxia inducible factor 2-alpha (HIF2a) is a stress response transcription factor that mediates the cellular response to hypoxia. HIF2a is an underexplored target in glioma. PT2385 is a first-in-class oral HIF2a inhibitor with favorable blood-brain barrier penetrating properties and in vivo single-agent activity against glioblastoma (GBM). METHODS: A single-arm open-label phase II study of adults with bevacizumab-naïve first recurrence of GBM following chemoradiation with measurable disease was conducted within the Adult Brain Tumor Consortium. PT2385 was administered at the recommended phase II dose (800 mg b.i.d.). The primary study outcome is objective radiographic response (CR+PR). Secondary objectives are safety, overall survival, and progression-free survival. Patients at selected study sites underwent pH-weighted amine-CEST MRI imaging to quantify tumor acidity at baseline and explore associations with drug response. Results of planned interim analysis are presented. RESULTS: 24 patients were enrolled; mean age 61 ± 11 years, 63% male, 92% white, median KPS 80. MGMT promoter was methylated in 46%, unmethylated in 50%, and indeterminate in 1 patient. Prior surgery included biopsy (8%), subtotal (38%) and gross total resection (54%). To date, 21 patients have progressed at a median of 7.7 weeks (95%CI 4.66–12.3 weeks). No objective radiographic responses have been observed. Three patients continue on treatment at a median of 19 weeks (95%CI 12–19.1). The drug was well tolerated with expected side effect profile. Common Grade 1–2 drug-related adverse events were anemia, dyspnea, and thrombocytopenia. Grade 3–4 drug-related adverse events included hypoxia (n=2, 8%), anemia (n=1, 4%), and hypophosphatemia (n=1, 4%). At baseline, pH-weighted MRI showed high levels of acidity and intratumoral heterogeneity. PK and PD data are forthcoming. CONCLUSIONS: Results of this planned interim analysis suggest that single-agent PT2385 has acceptable safety but minimal activity in glioblastoma patients after first recurrence. Ongoing analysis will explore patterns of progression and correlate these with tumor acidity measurements.

OBJECTIVES/SPECIFIC AIMS: In patients with recurrent glioblastoma (GBM) who undergo a second surgery following standard chemoradiotherapy, histopathologic examination of the resected tissue often reveals a combination of viable tumor and treatment-related inflammatory changes. However, it remains unclear whether the degree of viable tumor Versus “treatment effect” in these specimens impacts prognosis. We sought to determine whether the percentage of viable tumor Versus “treatment effect” in recurrent GBM surgical samples, as assessed by a trained neuropathologist and quantified on a continuous scale, is associated with overall survival. METHODS/STUDY POPULATION: We reviewed the records of 47 patients with histopathologically confirmed GBM who underwent surgical resection as the first therapeutic modality for suspected radiographic progression following standard radiation therapy and temozolomide. The percentage of viable tumor Versus “treatment effect” in each specimen was estimated by one neuropathologist who was blinded to patient outcomes. RESULTS/ANTICIPATED RESULTS: After adjusting for other known prognostic factors in a multivariate Cox proportional hazards model, there was no association between the degree of viable tumor and overall survival (HR 0.83; 95% CI, 0.20–3.4; p=0.20). DISCUSSION/SIGNIFICANCE OF IMPACT: These results suggest that, in patients who undergo resection for recurrent GBM following standard first-line chemoradiotherapy, histopathologic quantification of the degree of viable tumor Versus “treatment effect” present in the surgical specimen has limited prognostic influence and clinical utility.

We have initiated a first-in-human pilot study of intravenous delivery of autologous T cells re-directed to the EGFR variant III mutation by means of a lentiviral vector encoding a chimeric antigen receptor (CAR). Patients with recurrent or incompletely resected glioblastoma (GBM) have their tumors screened for the presence of the EGFRvIII mutation by a next-generation sequencing based assay. Eligible patients undergo leukapheresis for collection of autologous T cells, which are then manufactured to form CART-EGFRvIII T cell products. We report preliminary results on the first six patients we have treated. We targeted a challenging subset of GBM patients, with multi-focal recurrent, residual, progressive disease refractory to standard and experimental therapies, including chemotherapy, radiation, bevacizumab and prior immunotherapy. To date, we have found that infusion of CART-EGFRvIII cells is safe, without evidence of off-tumor toxicity such as cross-reactivity to wild type EGFR. No clinical or laboratory signs of systemic cytokine release syndrome have been observed. One patient developed a seizure and non-convulsive status epilepticus nine days after CART-EGFRvIII infusion. Seizures resolved with anti-epileptic medications, and the patient was treated with steroids and anti-IL6 cytokine therapy. All patients have had significant expansion of CART-EGFRvIII cells as measured by flow cytometry and quantitative PCR in peripheral blood samples, despite the use of steroids in two patients. In one of two patients who had operative resection of presumed residual tumor, pathologic evaluation demonstrated inflammation, T cell infiltration, and EGFRvIII antigen loss. In total, two of six heavily pretreated patients are clinically stable three months post-CART infusion. These findings provide preliminary evidence that CART-EGFRvIII cells are safe, without evidence of off-target toxicity and without evidence of cytokine release syndrome, and that these are active T cell products that expand in the blood.

BACKGROUND: Mibefradil (MIB) is a selective T-type calcium channel blocker that has shown preclinical impact on cell cycle activity, specifically arrest at G1/S in tumor cells, suggesting a potential chemo-sensitizing effect if given prior to chemotherapy. In our study, MIB was administered orally QID x 7 days prior to standard temozolomide (150-200 mg/m2 x 5/28d) in recurrent high-grade glioma (HGG) patients. 18F-FLT PET was used as an exploratory imaging biomarker to assess influence of MIB on overall tracer accumulation in tumor. METHODS: 18F-FLT PET was performed in 10 patients treated at the maximum tolerated dose of MIB (87.5 mg po QID) at 5 different institutions. Prior to MIB administration, 2 PET scans were performed as a double baseline to assess repeatability of PET measurements. A third scan was performed on day 7 of MIB treatment to assess 18F-FLT uptake for response. Tumor standardized uptake values (SUVs) were measured at a central laboratory by automatically positioning a 1mL sphere at the region of highest uptake (SUVpeak). RESULTS: The double baseline data indicated 95% limits of repeatability of 18.5% (6.7% within-patient coefficient of variation) for SUVpeak. Two of the 10 patients demonstrated a drop in SUVpeak after 7 days of MIB that exceeded these limits (-47% and -67%). No significant change between double baseline and day 7 of MIB was seen in the remaining 8 patients. CONCLUSIONS: In this first 18F-FLT PET imaging study within a multicenter HGG trial, 18F-FLT PET was found to be feasible and highly repeatable. The results suggest influence of MIB on tumor accumulation of the radiotracer, possibly in part due to alterations in cell cycle activity in a subset of patients, but the precise mechanism remains to be determined as tracer delivery/transport effects may also be contributing to the decline in signal observed in the two patients.

The blood-brain-barrier (BBB) limits the penetration of many systemic antineoplastic therapies. Consequently, many agents may be used in clinical studies and clinical practice though they may not achieve therapeutic levels within the tumor. We sought to compile the currently available human data on antineoplastic drug concentrations in brain and tumor tissue according to BBB status. A review of the literature was conducted for human studies providing concentrations of antineoplastic agents in blood and metastatic brain tumors or high-grade gliomas. Studies were considered optimal if they reported simultaneous tissue and blood concentration, multiple sampling times and locations, MRI localization, BBB status at sampling site, tumor histology, and individual subject data. Twenty-Four studies of 19 compounds were included. These examined 18 agents in contrast-enhancing regions of high-grade gliomas, with optimal data for 2. For metastatic brain tumors, adequate data was found for 9 agents. Considerable heterogeneity was found in the measurement value, tumor type, measurement timing, and sampling location within and among studies, limiting the applicability of the results. Tissue to blood ratios ranged from 0.054 for carboplatin to 34 for mitoxantrone in high-grade gliomas, and were lowest for temozolomide (0.118) and etoposide (0.116), and highest for mitoxantrone (32.02) in metastatic tumors. The available data examining the concentration of antineoplastic agents in brain and tumor tissue is sparse and limited by considerable heterogeneity. More studies with careful quantification of antineoplastic agents in brain and tumor tissue is required for the rational development of therapeutic regimens.

2048Background: Distinguishing between radiographic pseudoprogression and true tumor progression is a significant challenge in patients with GBM. A non-invasive means of assessing GBM disease activ...

2005 Background: The standard of care treatment for newly diagnosed GBM is maximal safe surgical resection followed by two DNA damaging agents, RT and TMZ. Cellular response to DNA damage involves checkpoints that halt the cell cycle to allow DNA repair. AZD1775 is an oral small molecular inhibitor of a nuclear tyrosine kinase Wee1, a key regulator of the G2/M checkpoint. Abrogation of the G2/M checkpoint prevents repair and pushes cells into mitosis with unrepaired DNA damage. AZD1775 was shown to enhance TMZ and RT effects in preclinical models. Methods: The Adult Brain Tumor Consortium 1202 trial (NCT01849146) is a phase I, open label, multicenter dose-finding study of AZD1775 in combination with standard RT and TMZ followed by an IDD study for patients undergoing surgery for recurrent GBM. The dose finding portion is comprised of two arms, one with AZD1775 given Monday through Friday during concurrent RT/TMZ and a second arm given with adjuvant TMZ qd x 5d/28d cycle. Each arm had standard 3+3 design. A combination cohort with both concurrent and adjuvant AZD1775 at MTD and analysis of PK/PD and IDD at MTD in patients undergoing surgery for recurrent GBM followed. Results: 51 patients enrolled in the dose finding arms. For the concurrent arm, the MTD was 200 mg. At 275 mg one patient had grade 3 fatigue and another had grade 4 thrombocytopenia and neutropenia. Two of 6 total patients enrolled at 200 mg experienced DLTs (grade 4 neutropenia and grade 3 ALT elevation). The MTD for the adjuvant arm was 425 mg as 1 of 6 patients had DLT (grade 4 decrease in ANC). At 500 mg, 2 of 3 patients experienced intolerable diarrhea despite prophylaxis. Enrollment in the combination cohort is completed and evaluation of safety is underway. The drug concentration in contrast enhancing and non-enhancing brain tumor was 4-8 x and 0.5-2.6 x greater than plasma, respectively for patients on IDD portion. Conclusions: The MTD for AZD1775 in combination with RT/TMZ is 200 mg qd M-F with concurrent RT/TMZ and 425 mg qd x 5d/28d cycle in combination with adjuvant TMZ. IDD and PK/PD analysis is ongoing to inform the decision to proceed to phase II testing. Clinical trial information: NCT01849146.

Although controversy exists in the management of locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN), clinicians often use induction chemotherapy for treatment of the most advanced cases. One promising regimen combines weekly cetuximab (400 mg/m2 loading dose followed by 250 mg/m2) with carboplatin (AUC of 2) and paclitaxel (90 mg/m2). We retrospectively evaluated patients treated with this regimen prior to definitive chemoradiation or surgery between May 2008 and December 2011. The primary endpoint used for this retrospective analysis was feasibility. Thirty consecutive, unselected patients were included. Median follow-up was 13.7 months (range, 5.0–38.7 months). All but one patient had stage IV SCCHN. Dose intensity was high for carboplatin (92%), paclitaxel (93%) and cetuximab (85%). Grade 3–4 toxicities occurred in