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Background Approximately 50% of newly diagnosed glioblastomas (GBMs) harbor epidermal growth factor receptor gene amplification (EGFR-amp). Preclinical and early-phase clinical data suggested efficacy of depatuxizumab mafodotin (depatux-m), an antibody–drug conjugate comprised of a monoclonal antibody that binds activated EGFR (overexpressed wild-type and EGFRvIII-mutant) linked to a microtubule-inhibitor toxin in EGFR-amp GBMs. Methods In this phase III trial, adults with centrally confirmed, EGFR-amp newly diagnosed GBM were randomized 1:1 to radiotherapy, temozolomide, and depatux-m/placebo. Corneal epitheliopathy was treated with a combination of protocol-specified prophylactic and supportive measures. There was 85% power to detect a hazard ratio (HR) ≤0.75 for overall survival (OS) at a 2.5% 1-sided significance level (ie traditional two-sided p ≤ 0.05) by log-rank testing. Results There were 639 randomized patients (median age 60, range 22–84; 62% men). Prespecified interim analysis found no improvement in OS for depatux-m over placebo (median 18.9 vs. 18.7 months, HR 1.02, 95% CI 0.82–1.26, 1-sided p = 0.63). Progression-free survival was longer for depatux-m than placebo (median 8.0 vs. 6.3 months; HR 0.84, 95% confidence interval [CI] 0.70–1.01, p = 0.029), particularly among those with EGFRvIII-mutant (median 8.3 vs. 5.9 months, HR 0.72, 95% CI 0.56–0.93, 1-sided p = 0.002) or MGMT unmethylated (HR 0.77, 95% CI 0.61–0.97; 1-sided p = 0.012) tumors but without an OS improvement. Corneal epitheliopathy occurred in 94% of depatux-m-treated patients (61% grade 3–4), causing 12% to discontinue. Conclusions Interim analysis demonstrated no OS benefit for depatux-m in treating EGFR-amp newly diagnosed GBM. No new important safety risks were identified.

Background Olutasidenib (FT-2102) is a highly potent, orally bioavailable, brain-penetrant and selective inhibitor of mutant isocitrate dehydrogenase 1 (IDH1). The aim of the study was to determine the safety and clinical activity of olutasidenib in patients with relapsed/refractory gliomas harboring an IDH1R132X mutation. Methods This was an open-label, multicenter, nonrandomized, phase Ib/II clinical trial. Eligible patients (≥18 years) had histologically confirmed IDH1R132X-mutated glioma that relapsed or progressed on or following standard therapy and had measurable disease. Patients received olutasidenib, 150 mg orally twice daily (BID) in continuous 28-day cycles. The primary endpoints were dose-limiting toxicities (DLTs) (cycle 1) and safety in phase I and objective response rate using the Modified Response Assessment in Neuro-Oncology criteria in phase II. Results Twenty-six patients were enrolled and followed for a median 15.1 months (7.3‒19.4). No DLTs were observed in the single-agent glioma cohort and the pharmacokinetic relationship supported olutasidenib 150 mg BID as the recommended phase II dose. In the response-evaluable population, disease control rate (objective response plus stable disease) was 48%. Two (8%) patients demonstrated a best response of partial response and eight (32%) had stable disease for at least 4 months. Grade 3‒4 adverse events (≥10%) included alanine aminotransferase increased and aspartate aminotransferase increased (three [12%], each). Conclusions Olutasidenib 150 mg BID was well tolerated in patients with relapsed/refractory gliomas harboring an IDH1R132X mutation and demonstrated preliminary evidence of clinical activity in this heavily pretreated population.

While the COVID-19 pandemic has catalyzed the expansion of telemedicine into nearly every specialty of medicine, few articles have summarized current practices and recommendations for integrating virtual care in the practice of neuro-oncology. This article identifies current telemedicine practice, provides practical guidance for conducting telemedicine visits, and generates recommendations for integrating virtual care into neuro-oncology practice. Practical aspects of telemedicine are summarized including when to use and not use telemedicine, how to conduct a virtual visit, who to include in the virtual encounter, unique aspects of telehealth in neuro-oncology, and emerging innovations.

BackgroundSerclutamab talirine (Ser-T, formerly ABBV-321) is an antibody-drug conjugate consisting of an antibody (AM-1-ABT-806) directed against activated epidermal growth factor receptor (EGFR) and a pyrrolobenzodiazepine dimer. We investigated Ser-T monotherapy in a phase I, first-in-human, dose-escalation, and dose-expansion study in patients with advanced solid tumors associated with EGFR overexpression.MethodsEligible patients (≥18 years) had advanced, histologically confirmed solid tumors associated with EGFR overexpression (centralized testing). Patients received Ser-T intravenously once every 4 weeks (Q4W; 5–50 μg/kg) in the dose-escalation phase. Herein, preliminary antitumor activity at the recommended phase II dose (RP2D) is reported only for patients with glioblastoma (n = 24); additional assessments included all treated patients.ResultsSixty-two patients (median age: 58 years) were enrolled within the dose-escalation (n = 43) and dose-expansion (n = 19) phases. One dose-limiting toxicity, grade 3 aspartate aminotransferase and alanine aminotransferase elevation, occurred at 20 μg/kg during dose escalation. The Ser-T RP2D regimen of 50 μg/kg × 1 (loading dose) followed by 25 μg/kg Q4W (maintenance dose) was administered during dose expansion. Fatigue (37%) was the only treatment-emergent adverse event (AE) occurring in >25% of patients. Two patients (3%) reported mild treatment-related ocular AEs (eye pruritus). Responses in patients with glioblastoma included 1 partial response (~33 months), 6 stable disease, and 14 progressive disease (not evaluable: n = 3).ConclusionsSer-T monotherapy at doses up to 50 μg/kg initial dose, followed by 25 μg/kg Q4W demonstrated a tolerable safety profile with minimal antitumor activity observed in patients with glioblastoma. The glioblastoma dose-expansion cohort was closed due to a lack of efficacy (NCT03234712).

BACKGROUND Grade 2 and 3 (G2/3) gliomas are the second largest group of brain tumors in adults. Although the prognosis for G2/3 gliomas at the time of relapse mirror those of glioblastoma, there are few trials in this space. METHODS LUMOS was a national multi-center pilot study for patients with relapsed G2/3 gliomas designed to match contemporaneous tissue obtained at the time of disease progression with subsequent targeted therapies. The objective was to establish the feasibility of a precision oncology, umbrella approach to obtain and type tissue within a useful timeframe. As a key feature of LUMOS, a multidisciplinary Molecular Tumor Advisory Panel (MTAP) with subspecialty neuro-oncology expertise was formed to interpret the complex genomic information and provide a simplified recommendation to the treating physician. RESULTS Ten patients (median age 42: range 32-62; four G2 astrocytoma, one G3 astrocytoma, three G2 oligoendroglioma, one G3 oligodendroglioma, one mixed tumor) were enrolled in the study. Eight patients had biopsies within 6 months of study entry whilst two underwent a biopsy during the study. All patients had potentially targetable alterations (10 IDH, 3 FGFR, 2 PIK3K, CCND3, NRAS, CDK4, PRPRZ1-MET fusion and MET amplification). Matched therapies were delivered for two patients via compassionate access outside the study. The median turnaround time (TAT) of MTAP reports was 6.2 weeks (range 4.2-9.7 weeks) but 4.6 weeks when lag time for shipping was removed. CONCLUSION LUMOS confirmed that this design was feasible with good turnaround times. The MTAP facilitated education and support for treating physicians. Thes findings support moving to a larger study using contemporaneous and longitudinal tissue samples matched with targeted therapies as part of a comprehensive umbrella study design. Delivery and interpretation of molecular data is a challenge shared across oncology which may be mitigated with a neuro-oncology specific molecular tumor board.

BACKGROUND Survival outcomes for patients with newly diagnosed glioblastoma have not changed significantly since the introduction of concurrent temozolomide with post-surgical radiation followed by adjuvant temozolomide. METHODS Multi-Arm Glioblastoma Australasia (MAGMA) is a recently initiated phase III multi-arm, multi-centre randomized trial for patients with newly diagnosed glioblastoma, led by the Australian Cooperative Trials Group for Neuro-Oncology (COGNO), that will concurrently test multiple treatment questions. Initially, a partial factorial design will be implemented to compare the current standard of care with either or both of (1) neoadjuvant temozolomide and (2) aduvant temozolomide continued beyond six months until progression. MAGMA will transition to a multi-arm multi-stage (MAMS) design as additional tratment question are introduced. Treatment allocation to each question will be balanced (1:1) using minimisation over several stratification factors, including study site, age, IDH-mutation status, surgical extent and randomization to the prior treatment question(s). The primary outcome is overall survival. Secondary outcomes include progression-free survival (measured by mRANO), time to first non-temozolomide systemic treatment, clinically significant toxicity as measured by Grade 2/4 adverse events, and health-related quality of life measures. Parsimonious data collection and a streamlined assessment schedule have been incorporated to mitigate the burden of data collection (such as low grade toxicity from temozolomide), and to encourage participation in regional and rural settings. A consortium model has been adopted to foster neuro-oncology expertise and infrastructure and share academic credit and future design opportunities. PROGRESS Recruitment commenced in September 2020. To date, 60 patients have been recruited from an initial sample size target of 250 patients for each of these initial two treatment questions. Of these 60 patients, 45 have been randomized in Question 1 (neoadjuvant chemotherapy) whilst 50 randomized in Question 2 (prolonged adjuvant chemotherapy). To date, 14 of the 27 intended sites are open to recruitment.

Primary and metastatic tumors of the central nervous system present a difficult clinical challenge, and they are a common cause of disease progression and death. For most patients, treatment consists primarily of surgery and/or radiotherapy. In recent years, systemic therapies have become available or are under investigation for patients whose tumors are driven by specific genetic alterations, and some of these targeted treatments have been associated with dramatic improvements in extracranial and intracranial disease control and survival. However, the success of other systemic therapies has been hindered by inadequate penetration of the drug into the brain parenchyma. Advances in molecular characterization of oncogenic drivers have led to the identification of new gene fusions driving oncogenesis in some of the most common sources of intracranial tumors. Systemic therapies targeting many of these alterations have been approved recently or are in clinical development, and the ability to penetrate the blood-brain barrier is now widely recognized as an important property of such drugs. We review this rapidly advancing field with a focus on recently uncovered gene fusions and brain-penetrant systemic therapies targeting them.Implications for PracticeDriver gene fusions involving receptor tyrosine kinases have been identified across a wide range of tumor types, including primary central nervous system (CNS) tumors and extracranial solid tumors that are associated with high rates of metastasis to the CNS (e.g., lung, breast, melanoma). This review discusses the systemic therapies that target emerging gene fusions, with a focus on brain-penetrant agents that will target the intracranial disease and, where present, also extracranial disease.

The FIG study is a prospective non-randomised study now recruiting up to 210 newly diagnosed GBM participants across ten Australian sites. Study outcomes will address the role of [18F] fluoroethyl-L-tyrosine positron emission tomography (FET-PET) in radiotherapy (RT) planning, evaluation of post-treatment changes versus disease progression and prognostication. We describe here the methodology and preliminary outcomes for site credentialing. Eligible participants with GBM undergo FET-PET imaging at three time-points: FET-PET1-post-operative pre-chemo-RT, FET-PET2 acquired one month post-chemo-RT and FET-PET3 (+/-FDG-PET) triggered when clinical and/or radiological (MRI) progression is suspected. Dynamic and static FET-PET images are analysed qualitatively and quantitatively. Radiotherapy is as per standard care with the treating Radiation Oncologist (RO) blinded to FET-PET1. Site nuclear medicine (NM) physicians are required to delineate a biological target volume (BTV) based on FET-PET1 with hybrid RT volumes derived post-hoc. Pre-trial NM quality assurance comprises certification from the Australasian Radiopharmaceutical Trials Network encompassing FET-PET radiochemistry Quality Control and PET camera calibration. Site and central integrated workflows incorporating multi-modality image registration, target volume/region of interest contouring and analysis have been developed. NM benchmarking involves delineation of FET-PET BTVs in 3 cases with another 3 cases addressing response criteria interpretation harmonized across FET-PET, FDG-PET and MRI. Site ROs complete 3 cases involving standard and hybrid target volume delineation based on pre-derived FET-PET volumes. All NM and RO credentialing cases undergo central expert review. To date, of six sites which have submitted full credentialing data, 19/21 RO and 6/6 planning cases were passed. Of 72 NM cases, 18/72 (25%) required resubmission, primarily related to ensuring standardisation of background regions and time activity curve interpretation. The FIG study will be pivotal in establishing the role of FET-PET in GBM management. The robust NM and RO credentialing program will build capacity and expertise in FET-PET production, acquisition and image interpretation.

INTRODUCTION No drug has improved survival in recurrent glioblastoma despite encouraging activity preclinically. We undertook a systematic review of matched preclinical and Phase 1 trials (P1Ts) of targeted agents to investigate potential preclinical predictors of clinical efficacy. METHODS We identified all adult glioblastoma monotherapy P1Ts of targeted agents & preceding preclinical data published between 2006–2019 via structured searches of EMBASE/MEDLINE/PUBMED. For preclinical studies, data regarding in vitro models, in vivo models (species, implantation site, cell-line type) and efficacy (growth inhibition, regression rate, survival) were extracted. For P1T, response rate (RR) data were collected as absolute (%) and categorical (RR< 5% vs. RR≥ 5%) variables. Associations were compared by chi-square/Fisher’s exact test, Kruskal-Wallis or Mann-Whitney U testing as appropriate with 2-sided p-values. RESULTS We found 28 P1Ts with median RR 2.9% (range 0.0–33.3%) and mOS 8.0mo (range 4.6–13.0mo). Seven (25%) had ‘minimal’ published pre-clinical data (5 missing entirely; 2 in vitro only); 12 (43%) utilised one cell line in vivo (‘single model’ group); and 9 (32%) used 2+ biologically distinct in vivo models (‘orthogonal’ group). There was strong reliance on U87-based cell lines (14/21 (71%)) in the latter groups. None of the variables tested were associated with RR except for use of ‘orthogonal models’. Compared to the ‘orthogonal’ group, the P1T RR rate was lower in ‘single’ and ‘minimal’ groups (6.8% vs 1.2%, p= 0.043 and 6.8% vs 0.0%, p= 0.026 respectively). The frequency of P1T with a RR > 5% was also higher in the ‘orthogonal’ compared to the same two groups (78% vs 20%, p= 0.042 and 78% vs 17%, p= 0.041). CONCLUSION The availability of good quality pre-clinical data, especially the use of orthogonal models in vivo, was significantly associated with P1T response rates and warrants further investigation as a minimal threshold of evidence in future drug development.

RTOG 3508/AbbVie M13-813/INTELLANCE-1 was a phase 3 trial of depatuximab-mafodotin (depatux-m, formerly ABT-414) that accrued 639 patients with EGFR-amplified newly diagnosed GBM. At the pre-specified interim OS analysis, the futility criteria were met and there was no survival benefit from adding depatux-m to SOC. Pre-specified secondary NCF analyses included time to decline in verbal learning and memory as assessed by the HVLT-R Total Recall based on the reliable change index. Exploratory NCF analyses examined changes in other HVLT-R outcomes over time. As corneal epitheliopathy causing visual impairment is a known toxicity of depatux-m, NCF tests that did not depend on visual acuity were employed. NCF testing occurred at baseline, day 1 of the first cycle of adjuvant depatux-m, every other cycle (i.e., 8 weeks) thereafter, and at progression. Compliance with test completion was 95% at screening and 80%, 70%, 58%, 51%, 47% thereafter through cycle 9. The most common reasons for missing data was site error. Time to HVLT-R Total Recall decline trended worse in the depatux-m arm compared to placebo but the difference was not significant (12 month deterioration: 41.2%, 95% CI: 3.50–47.2 vs 32.4%, 95% CI: 26.6- 38.4, p=0.052). The depatux-m arm, in comparison to the placebo arm, showed greater decline from baseline on the HVLT-R at the following time points: cycle 3 (Total Recall: mean= -1.8, SD=5.7 vs mean= -0.5, SD=5.5, respectively, p=0.046; Delayed Recall: mean= -1.1, SD=3.0 vs. mean= -0.2, SD=2.7, respectively, p=0.01), cycle 7 (Total Recall: mean= -0.6, SD=5.1 vs mean= 1.4, SD=5.0, respectively, p=0.009; Delayed Recall: mean -0.6, SD=3.0 vs. mean= 0.5, SD=2.7, respectively, p=0.01), and cycle 9 (Delayed Recall: mean=-0.4, SD=2.7 vs. mean= 0.8, SD=2.4, respectively, p=0.003). Depatux-m added to concurrent chemoradiation and adjuvant temozolomide was associated with faster time to deterioration and worse episodic learning and memory over time than placebo.

Glioblastoma (GBM) is the most frequent and lethal primary brain neoplasm. EphA3 is a tumor restricted antigen expressed in 38–40% of GBM and 100% of the tumor vasculature. Ifabotuzumab is a non-fucosylated IgG1κ antibody targeting EphA3 receptor. A Phase 1 study of ifabotuzumab in haematological malignancies was well tolerated and clinically active. Here we report on a Phase I dose escalation and biodistribution study of ifabotuzumab in recurrent glioblastoma. DESIGN The primary objective is to determine the toxicity and recommended phase II dose of Ifabotuzumab in GBM patients (pts). Secondary objectives are to determine the biodistribution and pharmacokinetics (PK) of 89Zr-Ifabotuzumab, the frequency of EphA3 positive GBM and response rates. Eligible pts received a trace (5mg) dose of zirconium-89 labelled ifabotuzumab (89Zr-ifab) on day 1 followed by sequential PET imaging over 1 week to determine its biodistribution, frequency of in situ EphA3 expression and tumor uptake. Safety and PK assessments were undertaken. On Day 8, pts commenced weekly ifabotuzumab infusions until PD. Three cohorts are planned (3.5mg/kg, 5.25 mg/kg, 7.9 mg/kg). On day 36, pts received both 89Zr-ifab and Ifabotuzumab, to assess receptor occupancy. Response rate (RANO) and survival data were collected. RESULTS: To date, 7 of 12 pts have enrolled (6 at 3.5 mg/kg,1 at 5.25 mg/kg; Mean age: 55 years (±12.6), 4 are male). Treatment emergent AEs included infusion reactions, seizures, cerebral oedema, rash, pruritis, headaches, eye disorder. Most were considered related to study drug, seizures and infusion reactions were readily managed with increased premedications after the first occurrence. Best response in cohort 1 is SD for 23 weeks. 89Zr-ifab PET/CT scans showed rapid, specific targeting at all known tumor sites and in all pts, but no normal tissue uptake. MRI scans showed predominant T2/FLAIR changes, occasionally marked, which were consistent with treatment effect on tumor vasculature.

INTRODUCTION We undertook a literature review testing the hypothesis that inefficiencies in the Phase 2/3 transition contributes to most GBM Phase 3 trials (P3T’s) being negative. METHODS Studies between 2005–2019 inclusive were identified though MEDLINE(R) using keywords and MeSH terms, and manual bibliography searches. Clinical, statistical and sponsor characteristics were extracted by two reviewers (AB&AG). For each P3T, Phase 2 trial (P2T) data was “optimally matched” where same drug was used in similar schedule and GBM population; “partially matched” where dis-similar schedule and/or treatment setting; and “lacking” in all other circumstances. Data were compared by Pearson Correlation, t-test or chi-square as appropriate. RESULTS 18 relevant P3T’s and 15 P2T’s were identified. Median values for median progression free survival (mPFS) and median overall survival (mOS) in P3T’s were 7.9 and 17.9 mths respectively for first line studies; 2.2 and 7.9 mths for recurrent studies. These were 11.8 and 20.4 mths for 1st line P2T’s, suggesting selection bias, and 3.3 and 7.5 mths for recurrent studies. 50% of P3T had optimally matched P2D, with high concordance for mPFS (r2= 0.90, p< 0.01) and mOS (r2= 0.84, p< 0.01) between corresponding P3T and P2T. The remain 50% of P3T had ‘partially matched’ (22.2%) or lacked P2T data (27.8%). ‘Partially matched’ trials also had a high concordance for mPFS (r2= 0.92, p< 0.01) and mOS (r2= 0.83, p< 0.01). However, 80% of P3T planned for HR didn’t meet expected benefit. All first-line P2T with mPFS< 15 months and/or OS< 22 months had negative P3T. All recurrent P2T with mPFS< 5 months and mOS< 12 months had negative P3T. Impact of sponsors and molecular subtypes will be presented. CONCLUSIONS This review identified issues (selection bias, lack of appropriate P2T and possible underpowered P3T’s) at the Phase 2/3 interface and provides data for future trial design.

BACKGROUND: An increase of mutations as we age is well documented in GBM and in cancer in general. Elderly patients with GBM may have higher mutational burden and may be more likely to respond to immunotherapies. NUTMEG is a randomised Phase II study comparing post radiation NivolUmab and TMZ versus TMZ alone in Elderly patients with newly diagnosed GBM. METHODS: 102 patients will be randomized in a 2:1 allocation to receive short course RT (40Gy/15 daily fractions) and TMZ 75mg/m2) followed by 6 cycles of adjuvant TMZ (150-200mg/m2 days (D) 1–5 q28 days) with Nivolumab (240 mg D1, 15 q28 days for cycles (C) (1–4; 480 mg D1 Q 28 days for C5-6) versus 6 cycles of adjuvant TMZ (150-200mg/m2 D1-5 q28) alone. The study is stratified for ECOG performance status, age (< 70 vs 70), MGMT methylation and extent of resection. An independent safety monitoring committee is overseeing the trial and will review safety data for the first 10 patients treated on the experimental arm (TMZ + Nivolumab). The primary endpoint is Overall Survival (OS). Secondary endpoints include: 6 month Progression Free Survival, adverse events (AEs) and immune AEs, Quality of life, neurological function (NANO Scale), and correlation of modified RANO and iRANO in the experimental arm. Translational research endpoints include correlation of clinical endpoints with mutational burden, comprehensive immune characteristics and novel MRI sequences including pH-weighted MRIs. The expected proportion of patients alive at 24 months is predicted to be 15.7%. A hazard ratio of more than 0.69 in favour of the Nivolumab + TMZ arm will be considered sufficient to warrant further investigation including converting this study into a phase III trial. PROGRESS: At 3 June 2018, 6/18 study sites are open in Australia with 5 patients randomized. ACTRN12617000267358.

BACKGROUND: Adverse biophysical factors (abnormal vessels and increased interstitial pressure) are increased in larger brain tumors, which negatively impacts penetration of antibody drug conjugates (ADC). The tumour-specific anti-EGFR ADC, depatuxizumab mafadotin (depatux-m), demonstrated encouraging activity in a Phase 1 glioblastoma study (M12-356 study, NCT01800695). The impact of tumour size on depatux-m efficacy was investigated. PRECLINICAL STUDY: Forty mice were engrafted with patient derived xenografts from an M12-356 patient. Eight mice were imaged in a zirconium-labelled depatux-m (3mg/kg) biodistribution study at small (70mm3,n=2) or large (350mm3,n=2) tumour volumes; another 4 mice were imaged with a control ADC. In the controls, non-specific uptake due to blood pool activity was 5% ID/g. In the 89Zr-depatux-m treated groups, mice with larger tumours had significantly less uptake compared smaller tumours (11 vs 21 %ID/gram, p 25cm3 vs 17% in < 25cm3, p=0.009) and worse overall survival (0.52 vs 0.81 years, p=0.001). The results were similar in patients treated with depatux-m monotherapy for response (n=60, 0% vs 10%, p=0.287) and survival (n=62, 0.50 vs 0.89 years, p=0.001) CONCLUSIONS: Increased tumour volumes results in significant reduction in ADC penetration. The impact of this as a modifiable factor, within the broader prognostic impact of increased tumour volume, warrants further investigation with prospective and/or randomized data.

BACKGROUND: Depatuxizumab mafodotin (depatux-m) is an antibody-drug conjugate (ADC) composed of an EGFR-targeted antibody conjugated to a microtubule inhibitor warhead, monomethyl auristatin F. In a Phase 1 study in glioblastoma (GBM), selection for EGFR amplification (amp) enriched for patients (pts) likely to respond. We sought to identify other determinants of sensitivity. MATERIAL AND METHODS: We identified an index case with prolonged disease control but unexpectedly without EGFR amp. Whole exome sequencing (WES) of pre-treatment archival tissue identified a point mutation in TUBA3C (tubulin alpha 3c) which mechanistically affects sensitivity to the microtubule-directed warhead of depatux-m, as opposed to the EGFR-targeted antibody. WES analysis, with a focus on the tubulin gene family, was expanded to 48 pts with sufficient archival tissue. In vitro synthetic lethality experiments were performed to confirm the hypothesized importance of tubulin mutations on depatux-m sensitivity. RESULTS: WES revealed some tubulin genes were differentially mutated in depatux-m responders (n = 8) vs non-responders (n = 24), all with EGFR amp. TPPP2, TTLL11, TTLL6, TTLL7, TUBA3C, TUBA3D, TUBAL3, and TUBGCP4 mutations (1–2 per tumor) were observed preferentially in responders; gene knockdown enhanced response in vitro, consistent with mechanistic relevance to warhead sensitivity. TTLL2, TTLL4, TUBB2A, TUBB2B, TUBG1, TUBGCP2, TUBGCP5, TBCC, and TBCE mutations (1–3 per tumor) were observed exclusively in non-responders. CONCLUSION: Response to ADCs depends not only on the presence of the target antigen but also on sensitivity to the conjugated toxin. We identified tubulin gene family mutations correlating with response to the microtubule inhibitor warhead of the ADC depatux-m. While verification of this observation in an independent cohort is required, other experiments to elucidate the mechanism are ongoing. Further data will be presented. A proposed investigator-initiated trial encompassing tubulin mutations as an eligibility criterion is in development. These data related to warhead sensitivity of depatux-m may serve as a guide to support rational drug combination therapy in GBM.

Aim: Aberrant EGFR signaling plays a vital role in GBM oncogenesis. ABT414 comprises an EGFR targeted antibody conjugated to the toxic agent monomethylauristatin F. An open label, 3 arm, phase I study (NCT01800695) is underway to evaluate 3 different ABT414 regimens in GBM. To understand the population most suited for ABT414 therapy, assays measuring EGFR gene amplification/protein overexpression, and the presence of EGFRvIII mutation have been developed. Methods: Total EGFR and EGFRvIII expression were measured with reverse transcription polymerase chain reaction (RTPCR). EGFR gene amplification was detected with fluorescence in situ hybridization (FISH) using 2 probes: Vysis locus specific identifier EGFR probe and Vysis chromosome enumeration probe (CEP) 7 probe. FISH utilized Ratio of EGFR to CEP 7 to identify locus specific EGFR gene amplification. Total EGFR protein expression was analyzed via immunohistochemical (IHC) using Dako pharmDx™ IHC assay. Relative expression of total EGFR and presence of EGFRvIII mRNA were determined with quantitative RTPCR. Tumor tissues from 89 pts were used for these tests. Results: IHC and RTPCR confirmed expression of EGFR mRNA and protein are correlated in GBM tissue samples (Spearman correlation is -0.86, P = 0.0026). A strong association between EGFR gene amplification and mRNA overexpression was observed. EGFRvIII mRNA was detected almost exclusively in cases with EGFR amplification. Thus far, EGFR amplification has been confirmed in 23/29 pts tested. All 6/6 pts with confirmed objective radiographic responses by Response Assessment in NeuroOncology criteria displayed EGFR gene amplification, whereas only 5/6 pts had total EGFR mRNA overexpression using RTPCR. EGFRvIII expression by RTPCR was detected in 4/6 pts. Conclusions: Assays were developed to characterize EGFR gene amplification, EGFR mRNA and protein expression, EGFRvIII status, and used to characterize EGFR status of GBM samples from pts treated with ABT414 in ongoing phase I trial. When comparing EGFR status to pt outcome, EGFR amplification by FISH had strongest association with objective radiographic responses.

BACKGROUND: ABT-414 is an EGFR-targeted antibody conjugated to the toxic antimicrotubule agent monomethylauristatin F. In an ongoing phase I study (abstract by Gan et al), all confirmed responses as determined by RANO criteria have been restricted to patients whose tumors harbor EGFR amplification. Genomic analysis was performed to explore mechanisms associated with innate sensitivity and acquired resistance. METHODS: Whole exome sequencing (WES) of diagnostic tumor samples from relapsed glioblastoma patients treated with ABT-414 + temozolomide (TMZ) or ABT-414 alone was performed. WES data were correlated with EGFR amplification and EGFRvIII as determined by FISH and RT-PCR, respectively. To explore acquired resistance, tissue was collected prior to starting ABT-414/TMZ from a patient who had a complete response and again postrelapse. WES and RNAseq of collected tissue were performed to identify mutations and associated transcriptional changes occurring at relapse. RESULTS: WES has been completed for 13 patients (14 samples) and is ongoing for 11 additional samples. Of the 9 samples determined to be EGFR amplified by FISH, 8 were amplified by WES. All 5 samples determined to be EGFRvIII positive by RT-PCR were positive by WES. In the patient with serial tumor collection, EGFR amplification and EGFRvIII expression was not significantly altered postprogression. Mutations in 25 genes were detected only in the postrelapse biopsy including in TOP2A and TOPORS, both of which are reported to be associated with chemotherapeutic resistance. RNAseq demonstrated a 1.7-fold upregulation of TUBGCP4 at the time of relapse. Given the involvement of TUBGCP4 in tubulin biology, this may potentially influence sensitivity to ABT-414's microtubule toxin. CONCLUSIONS: To date, EGFR amplification is necessary but not sufficient for response to ABT-414. Genomic profiling of longitudinally collected tissue may suggest factors involved in treatment sensitivity and acquired resistance. Ongoing mutation analysis in additional samples will be presented.

BACKGROUND: Aberrant EGFR signaling plays a vital role in GBM oncogenesis. ABT-414 is an antibody-drug conjugate with a toxic payload (monomethylauristatin F) linked to ABT-806, an antibody targeted to activated EGFR. This phase I, open-label, 3-arm study (NCT01800695) evaluates ABT-414 mono- or combination therapy with TMZ rechallenge in patients with GBM. Herein, we report outcomes in recurrent GBM. METHODS: Eligible patients (≥18 years) had recurrent supratentorial GBM and Karnofsky performance status ≥70. ABT-414 was given intravenously every 2 weeks with TMZ rechallenge (150-200 mg/m2 days 1-5 q28; Arm B) or as monotherapy (Arm C). ABT-414 dose escalation used a modified continual reassessment method. Primary objectives were to assess ABT-414 safety, maximum tolerated dose (MTD), and recommended phase II dose (RPTD); secondary objectives included antitumor activity evaluation. RESULTS: As of April 2015, 19 Arm B patients were treated in 4 dose groups (0.5-1.5 mg/kg), and 27 Arm C patients were treated at 1.25 mg/kg. In Arms B/C, 10/17 patients had amplified EGFR. Most common grade 3/4 treatment-emergent adverse events in either arm were keratitis (11%/19%), γ-glutamyltransferase increase (16%/0%), convulsions (11%/0%), fatigue (11%/0%), and thrombocytopenia (11%/4%). ABT-414 MTD was 1.5 mg/kg in Arm B and was not reached in Arm C; RPTD is 1.25 mg/kg for both arms. Best objective responses were complete response (CR) in 3 patients and a partial response (PR) in 1 patient in Arm B, and 1 CR and 1 PR in Arm C patients (all confirmed responses were observed in patients with EGFR amplification).Objective response rate among EGFR-amplified subjects was 22.2% (6/27). CONCLUSIONS: RPTD for ABT-414 is 1.25 mg/kg for both combination therapy with TMZ rechallenge and monotherapy. ABT-414 demonstrated a unique safety profile including ocular AEs, and appears to have antitumor activity in recurrent GBM with EGFR amplification.

Glial tumors with oligodendroglial components are considered chemo-responsive. Forty newly diagnosed patients (11 anaplastic oligodendrogliomas [OD] and 29 anaplastic oligoastrocytomas [OA]) were enrolled into this multicenter, open-label, single-arm Phase II trial of first-line temozolomide (200 mg/m(2) on days 1-5 every 4 weeks for 6 cycles). The primary endpoint was 6-month progression-free survival (PFS) with response rate (RR), median PFS, and median overall survival (OS) as secondary endpoints. Of 39 evaluable patients at the 6-month time point (median follow-up, 34 months), 6-month PFS was 77% (95% confidence interval [CI], 74.5%-79.3%). There were 15 complete responses (CRs, 38%), 6 partial responses (PRs, 15%), and 9 disease stabilization (23%). The median PFS was 21 months (95% CI, 3-39 months), and the median OS was 43 months (95% CI, 20-66 months). Chromosome 1p/19q codeletions were seen in 47% (18 of 38) of the patients, and O-6-methylguanine-DNA-methyltransferase (MGMT) methylation was seen in 48% (10 of 21) of the patients. All patients with OD showed MGMT methylation and most (71%) had chromosome 1p/19q codeletions. Conversely, fewer patients with OA showed MGMT methylation (23%) or had chromosome 1p/19q codeletions (31%). The presence of either 1p/19q codeletion or MGMT methylation was associated with increased RR at 6 months but not with improved PFS or OS. Only 18% of the patients (7 of 40) experienced treatment-related grade 3/4 toxicities. This regimen was active and well tolerated. These data add to the growing body of data showing that primary chemotherapy may be an acceptable alternative to radiotherapy for patients with gliomas containing oligodendroglial histology.

BACKGROUND: Standard therapies have little effect on the poor survival rates of GBM. Abnormal epidermal growth factor receptor (EGFR) expression and signaling are common in GBM. ABT-414 is a unique antibody-drug conjugate, with a toxic payload (MMAF) targeted to active EGFR or mutant EGFRvIII, that has demonstrated high antitumor activity in preclinical GBM tumor models. METHODS: Objectives were to evaluate the safety, pharmacokinetics (PK), and the maximum tolerated dose (MTD) of ABT-414 when administered with TMZ (recurrent or unresectable GBM, Arm B) or concurrent RT and TMZ (newly diagnosed GBM, Arm A). Adverse events (AEs), PK parameters, objective response (RANO), and tumor tissue EGFR biomarkers were assessed. Dose escalation was determined by the continual reassessment method (CRM). RESULTS: As of April, 2014, 22/21 pts were treated in Arm A/B. Common treatment-emergent AEs included fatigue(n= 11/ 6, Arm A/B); blurred vision(n = 10/9); AST increase(n = 9, Arm A); and nausea(n = 7/7) Grade 3/4 AEs (≥ 2 pts) included lymphopenia(n = 3); eye toxicity(n = 3); brain edema, ALT, AST(n = 2 each) in Arm A and keratitis(n = 2) in Arm B. Doses from 0.5-3.2mg/kg have been explored. Dose limiting toxicities primarily affecting the eye (keratitis) and liver occurred at multiple doses. The CRM has predicted 2.4mg/kg as the MTD in Arm A and 1.25mg/kg in Arm B. Patient samples are being evaluated for EGFR expression, amplification and EGFRvIII status. Efficacy endpoints are not yet mature in Arm A, but 4 patients in Arm B have best responses of 3 PRs and 1 CR. CONCLUSIONS: PK and safety data support doses of 2.4 and 1.25mg/kg as the predicted MTD in Arms A and B. Preliminary safety data demonstrate liver and eye toxicities in Arm A and primarily eye toxicities in Arm B. Updated biomarker results as they correlate with efficacy will be reported. Phase 2 studies assessing ABT-414 in GBM are planned.