507 A phase 1 clinical trial of RP2, an enhanced potency oncolytic HSV expressing an anti-CTLA-4 antibody, as a single agent and combined with nivolumab in patients with advanced solid tumors

Background

RP2 is a first-in-class, enhanced potency oncolytic herpes simplex virus (HSV) -1 expressing GM-CSF, a fusogenic protein (GALV-GP R-), and an anti-CTLA-4 antibody-like molecule that is being tested in an open-label, multicenter, phase 1 study alone and combined with nivolumab (nivo). Preliminary data with RP2 as monotherapy has been presented previously [1–2]. We present updated safety, tolerability, and clinical activity data of RP2 alone and initial data in combination with nivolumab.

Methods

Using a 3+3 dose escalation, patients (pts) received intratumoral injections of up to 10 mL RP2 to superficial and/or visceral tumors Q2W up to 5 times at two dose levels (Dose level 1: 10^5 PFU/mL then 4 doses of 10^6 PFU/mL; dose level 2: 10^6 PFU/mL then 4 doses of 10^7 PFU/mL). Following determination of the RP2D (10^6 PFU/mL, followed by subsequent doses of 10^7 PFU/mL, Q2W X 7), a combination cohort of 30 pts were dosed with RP2 up to 8 times combined with nivo (240 mg Q2W for 4 mos from the second RP2 dose, then 480 mg Q4W for 20 mos). Re-initiation of up to 8 additional RP2 doses is permitted in prespecified circumstances.

Results

Nine pts were enrolled into the RP2 monotherapy phase (6 seropositive and 3 seronegative for HSV). Objective responses were observed in 3 pts, 1 ongoing CR for ≥15 months in mucoepidermoid carcinoma, 1 ongoing PR for ≥18 months in esophageal cancer with liver metastases, 1 PR in uveal melanoma with liver metastases that progressed at 15 months. As of June 3rd 2021, 27 patients had been enrolled and ongoing partial responses had been observed in 4/9 anti-PD-1 failed cutaneous melanoma, 1/3 uveal melanoma and 1/3 SCCHN pts. A further 8 patients remained on study with the opportunity for response. Biomarker analyses indicate T cell infiltration, increase in tumor inflammation signature, expansion of existing T cell clones and emergence of new T cell clones, together indicative of local and systemic anti-tumor activity. The combination was well tolerated and no new safety signals were identified.

Conclusions

RP2 ± nivo demonstrated good tolerability and durable systemic responses in pts with difficult-to-treat, heavily pretreated and anti-PD-1 failed advanced cancers. These data continue to support the hypothesis that oncolytic delivery of anti-CTLA-4 into tumors, with accompanying antigen release, presentation and immune activation, can provide potent systemic anti-tumor effects. Updated data from the full 30 patient cohort will be presented.

Trial Registration

NCT04336241

References

Aroldi F, Sacco J, Harrington K, Olsson-Brown A, Nanclares P, Menezes L, Bommareddy P, Thomas S, Kaufman H, Samakoglu S, Coffin R and Middleton M. 421, Initial results of a phase 1 trial of RP2, a first in class, enhanced potency, anti-CTLA-4 antibody expressing, oncolytic HSV as single agent and combined with nivolumab in patients with solid tumors Journal for Immuno Therapy of Cancer 2020;8.

Harrington KJ, Aroldi F, Sacco JJ, Milhem MM, Curti B, Vanderwalde A, et al. LB180-Clinical biomarker studies with two fusion-enhanced versions of oncolytic HSV (RP1 and RP2) alone and in combination with nivolumab in cancer patients indicate potent immune activation. Cancer Res 2021. LB-180

Ethics Approval

The study was approved by institutional review board or the local ethics committee at each site. Informed consent was obtained from patients prior to enrollment.

506 IGNYTE: an open-label, multicenter, phase 1/2 (Ph 1/2) clinical trial of RP1 ± nivolumab in patients with advanced solid tumors

Background

RP1 is an enhanced potency oncolytic HSV-1 which expresses a fusogenic glycoprotein (GALV-GP R-) and granulocyte macrophage colony stimulating factor (GM-CSF).1 In pre-clinical studies, RP1 demonstrated potent GALV-GP R-enhanced anti-tumor activity and immunogenic cell death. This Phase 1/2 (Ph 1/2) study was designed to evaluate the safety and efficacy of RP1 ± nivolumab (nivo) in patients (pts) with advanced solid tumors, including pts whose disease failed prior anti-PD-1/PD-L1 therapy and has reported promising interim data in a number of tumor types including cutaneous squamous cell carcinoma (CSCC) and anti-PD1 failed melanoma to date.2

Methods

This is a multi-center, first-in-human, open label, multi-cohort, non-randomized Ph1 study of RP1 alone and combined with nivo followed by Ph2 in combination with nivo in pts with recurrent advanced solid tumors including those that progressed after prior anti-PD-1/PD-L1 therapy. The Ph 1 monotherapy dose escalation (n=14) and RP-1 combination expansion (n=22) cohorts are fully enrolled. Approximately 260 pts are expected to be enrolled in the ongoing Ph 2 portion across five cohorts; melanoma (n=30, enrollment complete), non-melanoma skin cancer (n=45, to include 15 pts with anti-PD-1/PD-L1 failed disease), anti-PD-1 failed MSI-H/dMMR tumors (n=30), anti-PD-1/PD-L1-failed non-small-cell lung cancer (n=30) and a registration-directed cohort in anti-PD-1 failed cutaneous melanoma (n=125). Pts in the Ph 2 portion receive up to 10 mL of RP1 intratumorally into one or more superficial or deep seated/visceral lesions at the recommended Ph 2 dose (1x10^6 PFU/mL × 1 followed by 1x10^7 PFU/mL × 7, Q2W). Following the first dose of RP1, nivo (240 mg IV Q2W for 4 months then 480 mg IV Q4W for up to 2 years) is subsequently administered in combination. Pts may receive up to 8 additional doses of RP1 if they meet protocol-specified criteria. Tumor assessments are performed Q8W. The primary objectives of the Ph 2 part of the study are to assess the safety, tolerability, and overall response rate (ORR) of RP1 in combination with nivo, by independent review for the anti-PD1 failed melanoma cohort. Secondary objectives include duration of response, complete response rate, disease control rate, PFS, 1-year and 2-year survival rates. Exploratory objectives include biodistribution and shedding analysis of RP1 and biomarker studies, including analyses of tumor biopsies and blood samples. Enrollment is currently ongoing in the UK and US, with additional sites in the EU (including France and Spain) are expected to open in 2021.

Trial Registration

NCT03767348

References

Thomas S, Kuncheria L, Roulstone V, Kyula JN, Mansfield D, Bommareddy PK, Smith H, Kaufman HL, Harrington KJ, Coffin RS. Development of a new fusion-enhanced oncolytic immunotherapy platform based on herpes simplex virus type 1. J Immunother Cancer 2019;7(1):214.

Coffin R, Astley-Sparke P, and Middleton M (2021, June 3rd). Retrieved from https://ir.replimune.com/static-files/f4fe3349-e082-4d41-94a1-106ce7e78a23

Ethics Approval

The study was approved by institutional review board or the local ethics committee at each site. Informed consent was obtained from patients prior to enrollment.

550 ARTACUS: An open-label, multicenter, phase 1b/2 study of RP1 in solid organ transplant recipients with advanced cutaneous malignancies

Background

Solid organ transplantation (SOT) has emerged as an important lifesaving procedure for patients with a wide range of end-organ diseases characterized by dysfunction or specific organ function failure. SOT rejection is a major complication requiring patients (pts) to undergo lifelong immunosuppression to prevent allograft rejection.1Skin cancers (SCs) including cutaneous squamous cell carcinoma (CSCC) are common post transplant malignancies.2 SC in SOT pts is generally managed with surgical resection, radiation therapy and chemotherapy or targeted therapy. Use of immune checkpoint inhibitors in SOT recipients has improved outcomes but are associated with the high risk of allograft rejection.3–5 Thus, there is a high unmet need for a safe and effective treatment that also protects pts from allograft rejection. RP1 is an oncolytic virus (HSV-1) that expresses a fusogenic glycoprotein (GALV-GP R-) and granulocyte macrophage colony stimulating factor (GM-CSF). In preclinical studies, RP1 induced immunogenic tumor cell death and provided potent systemic anti-tumor activity6 and clinical data in combination with nivolumab has demonstrated a high rate of deep and durable response in patients with advanced SCs.7 The objective of this study is to assess the safety and efficacy of single agent RP1 in kidney and liver transplant recipients with SCs, with focus on CSCC. After determining the safety and tolerability in the initial cohort with kidney and liver transplants the study may also enroll heart and lung transplant recipients.

Methods

This study will enroll up to 65 evaluable allograft transplantation pts with locally advanced or metastatic SCs. Key inclusion criteria are pts with confirmed recurrent, locally advanced or metastatic CSCC and up to 10 pts with non-CSCC SC, stable allograft function and ECOG performance status of ≤1. Pts with prior systemic anti-cancer treatment are allowed. Key exclusion criteria are prior treatment with an oncolytic therapy, active herpetic infections or prior complications of HSV-1 infection and a history of organ graft rejection within 12 months. Pts will receive an initial dose of 1 x 10^6 plaque-forming units (PFU) of RP1. Two weeks later they will receive 1 x 10^7 PFU of RP1 and continue every two weeks until pre-specified study endpoints are met. RP1 will be administered by intra-tumoral injection including through imaging guidance as clinically appropriate. The primary objective of the trial is to assess efficacy determined by ORR and safety of single agent RP1. Additional secondary endpoints include DOR, CR, DCR, PFS and OS.

Trial Registration

NCT04349436

References

Frohn C, Fricke L, Puchta JC, Kirchner H. The effect of HLA-C matching on acute renal transplant rejection. Nephrol Dial Transplant 2001;16(2):355–60.

Madeleine MM, Patel NS, Plasmeijer EI, Engels EA, Bouwes Bavinck JN, Toland AE, Green AC; the Keratinocyte Carcinoma Consortium (KeraCon) Immunosuppression Working Group. Epidemiology of keratinocyte carcinomas after organ transplantation. Br J Dermatol 2017;177(5):1208–1216.

Spain L, Higgins R, Gopalakrishnan K, Turajlic S, Gore M, Larkin J. Acute renal allograft rejection after immune checkpoint inhibitor therapy for metastatic melanoma. Ann Oncol 2016;27(6):1135–1137.

Herz S, Höfer T, Papapanagiotou M, Leyh JC, Meyenburg S, Schadendorf D, Ugurel S, Roesch A, Livingstone E, Schilling B, Franklin C. Checkpoint inhibitors in chronic kidney failure and an organ transplant recipient. Eur J Cancer 2016;67:66-72.

Kittai AS, Oldham H, Cetnar J, Taylor M. Immune checkpoint inhibitors in organ transplant ptss. J Immunother 2017;40(7):277–281.

Thomas S, Kuncheria L, Roulstone V, Kyula JN, Mansfield D, Bommareddy PK, Smith H, Kaufman HL, Harrington KJ, Coffin RS. Development of a new fusion-enhanced oncolytic immunotherapy platform based on herpes simplex virus type 1. J Immunother Cancer 2019 10;7(1):214.

Middleton M, Aroldi F, Sacco J, Milhem M, Curti B, Vanderwalde A, Baum S, Samson A, Pavlick A, Chesney J, Niu J, Rhodes T, Bowles T, Conry R, Olsson-Brown A, Earl-Laux D, Kaufman H, Bommareddy P, Deterding A, Samakoglu S, Coffin R, Harrington K. 422 An open-label, multicenter, phase 1/2 clinical trial of RP1, an enhanced potency oncolytic HSV, combined with nivolumab: updated results from the skin cancer cohorts. J Immunother Cancer 2020;8(3): doi: 10.1136/jitc-2020-SITC2020.0422

Ethics Approval

The study was approved by institutional review board or the local ethics committee at each participating site. Informed consent was obtained from patients before participating in the trial.

Abstract LB180: Clinical biomarker studies with two fusion-enhanced versions of oncolytic HSV (RP1 and RP2) alone and in combination with nivolumab in cancer patients indicate potent immune activation

Introduction:RP1 and RP2 are novel, enhanced potency oncolytic versions of HSV1 engineered to express human GM-CSF and the gibbon ape leukemia virus membrane R- glycoprotein (GALV-GP R-), providing constitutive fusion activity and increased immunogenic cell death. RP2 further expresses an anti-CTLA-4 antibody-like molecule. Murine versions of RP1 and RP2 exhibited synergy in combination with anti-mouse-PD-1 leading to enhanced regression of both injected and un-injected tumors in mice (Thomas et al JITC 2019). RP1 and RP2 are currently being evaluated in clinical trials in a range of solid tumors alone and combined with anti-PD1 therapy, where deep and durable responses have been demonstrated (SITC 2020). Here we present biomarker data from the Phase 1/2 clinical trial of RP1 alone and combined with nivolumab (NCT03767348) and from the Phase 1 portion of the clinical trial with RP2 alone (NCT04336241).

Methods: In the Phase 1/2 studies tumor biopsies and peripheral blood mononuclear samples (PBMCs) were collected at screening and at D43 for biomarker analysis, after combination therapy with nivolumab for RP1 and following single agent treatment for RP2. Immunohistochemistry (IHC) was performed for CD8 (SP57 clone, Ventana) and for PD-L1 (28-8 clone, pharmDx assay). Gene expression was analysed using NanoString to assess effects on a range of genes. The tumor inflammation signature score (TIS) was also calculated.

Results:Preliminary Phase 1/2 biomarker data from paired tumor biopsies include the following: Immunohistochemistry for CD8 and PD-L1 (n=30) indicated robust and increased infiltration of CD8+ T cells and PD-L1 expression, both after combined treatment with RP1 and nivolumab and after single agent RP2 across different tumor types, and including reversal of T cell exclusion following prior combined treatment with ipilimumab and nivolumab in melanoma. Gene expression analysis (n=15) demonstrated a significant increase in the expression levels of genes associated with innate and adaptive immune activation and genes previously reported to be associated with responsiveness to anti-PD1 therapy, particularly CD8, CXCL9, CD27 and TIGIT, as well as consistently increased TIS.

Conclusion:Consistent with the pre-clinical data, preliminary clinical biomarker data indicate substantial increase in CD8 T cell infiltration and PD-L1 expression, as well as increased TIS score in the majority of patients treated with RP2 alone or RP1 and nivolumab combination. Particularly marked effects were seen in some patients with clinical responses which occurred independent of both baseline PD-L1 and prior anti-PD1 therapy status, which suggests potential broad utility of the RP1/2 treatment approach in igniting an anti-tumor immune response. Tumor mutation burden analysis and T cell receptor sequencing are currently underway and further updates of the dataset will be presented.

Citation Format: Kevin J. Harrington, Francesca Aroldi, Joseph J. Sacco, Mohammed M. Milhem, Brendan D. Curti, Ari M. Vanderwalde, Scott Baum, Adel Samson, Anna C. Pavlick, Jason A. Chesney, Jiaxin Niu, Terence D. Rhodes, Tawnya L. Bowles, Robert Conry, Anna Olsson-Brown, Douglas E. Laux, Pablo Nenclares, Lavita Menezes, Alex Deterding, Victoria Roulstone, Joan Kyula, Suzanne Thomas, Praveen K. Bommareddy, Selda Samakoglu, Andrea Pirzkall, Robert S. Coffin, Mark R. Middleton. Clinical biomarker studies with two fusion-enhanced versions of oncolytic HSV (RP1 and RP2) alone and in combination with nivolumab in cancer patients indicate potent immune activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB180.

Association of Cancer Immunotherapy With Acute Macular Neuroretinopathy and Diffuse Retinal Venulitis

Importance

Checkpoint inhibition in cancer immunotherapy related to T-cell-driven mechanisms of action associated with acute macular neuroretinopathy (AMN) and diffuse retinal venulitis, an adverse event not previously described, is reported here.

Objective

To describe 2 patients who developed ophthalmologic events after treatment with the programmed death 1 axis inhibitor, atezolizumab.

Design, Setting, and Participants

Retrospective review of 2 patients treated with atezolizumab for metastatic breast cancer and colon cancer, respectively, who presented with AMN and diffuse retinal venulitis conducted at 2 tertiary medical centers.

Main Outcomes and Measures

Multimodal imaging including near infrared, optical coherence tomography, and fluorescein angiography were used to characterize retinal vascular abnormalities.

Results

Based on optical coherence tomography and multimodal imaging findings, the clinical diagnosis of AMN associated with diffuse retinal venulitis was made in these 2 patients receiving atezolizumab.

Conclusions and Relevance

While only 2 cases of patients receiving the programmed death ligand 1 inhibitor atezolizumab who experienced AMN and diffuse retinal venulitis are described here, these findings suggest that patients receiving programmed death 1 axis inhibitor therapies may need to be monitored for unexpected immune-related ocular toxicity including abnormalities of the microvasculature and large retinal vessels. Further studies might investigate the potential mechanisms of retinal vascular changes associated with these therapies.

Investigation of the absolute bioavailability and human mass balance of navoximod, a novel IDO1 inhibitor

Aims

Navoximod (GDC‐0919, NLG‐919) is a small molecule inhibitor of indoleamine‐2,3‐dioxygenase 1 (IDO1), developed to treat the acquired immune tolerance associated with cancer. The primary objectives of this study were to assess navoximod's absolute bioavailability (aBA), determine the mass balance and routes of elimination of [¹⁴C]‐navoximod, and characterize navoximod's metabolite profile.

Methods

A phase 1, open‐label, two‐part study was conducted in healthy volunteers. In Part 1 (aBA), subjects (n = 16) were randomized to receive oral (200 mg tablet) or intravenous (5 mg solution) navoximod in a crossover design with a 5‐day washout. In Part 2 (mass balance), subjects (n = 8) were administered [¹⁴C]‐navoximod (200 mg/600 μCi) as an oral solution.

Results

The aBA of navoximod was estimated to be 55.5%, with a geometric mean (%CV) plasma clearance and volume of distribution of 62.0 L/h (21.0%) and 1120 L (28.4%), respectively. Mean recovery of total radioactivity was 87.8%, with 80.4% detected in urine and the remainder (7.4%) in faeces. Navoximod was extensively metabolized, with unchanged navoximod representing 5.45% of the dose recovered in the urine and faeces. Glucuronidation was identified as the primary route of metabolism, with the major glucuronide metabolite, M28, accounting for 57.5% of the total drug‐derived exposure and 59.7% of the administered dose recovered in urine.

Conclusions

Navoximod was well tolerated, quickly absorbed and showed moderate bioavailability, with minimal recovery of the dose as unchanged parent in the urine and faeces. Metabolism was identified as the primary route of clearance and navoximod glucuronide (M28) was the most abundant metabolite in circulation with all other metabolites accounting for <10% of drug‐related exposure.

Phase I Study of the Indoleamine 2,3-Dioxygenase 1 (IDO1) Inhibitor Navoximod (GDC-0919) Administered with PD-L1 Inhibitor (Atezolizumab) in Advanced Solid Tumors

PURPOSE

IDO1 induces immune suppression in T cells through l-tryptophan (Trp) depletion and kynurenine (Kyn) accumulation in the local tumor microenvironment, suppressing effector T cells and hyperactivating regulatory T cells (Treg). Navoximod is an investigational small-molecule inhibitor of IDO1. This phase I study evaluated safety, tolerability, pharmacokinetics, and pharmacodynamics of navoximod in combination with atezolizumab, a PD-L1 inhibitor, in patients with advanced cancer.

PATIENTS AND METHODS

The study consisted of a 3+3 dose-escalation stage (n = 66) and a tumor-specific expansion stage (n = 92). Navoximod was given orally every 12 hours continuously for 21 consecutive days of each cycle with the exception of cycle 1, where navoximod administration started on day -1 to characterize pharmacokinetics. Atezolizumab was administered by intravenous infusion 1,200 mg every 3 weeks on day 1 of each cycle.

RESULTS

Patients (n = 157) received navoximod at 6 dose levels (50-1,000 mg) in combination with atezolizumab. The maximum administered dose was 1,000 mg twice daily; the MTD was not reached. Navoximod demonstrated a linear pharmacokinetic profile, and plasma Kyn generally decreased with increasing doses of navoximod. The most common treatment-related AEs were fatigue (22%), rash (22%), and chromaturia (20%). Activity was observed at all dose levels in various tumor types (melanoma, pancreatic, prostate, ovarian, head and neck squamous cell carcinoma, cervical, neural sheath, non-small cell lung cancer, triple-negative breast cancer, renal cell carcinoma, urothelial bladder cancer): 6 (9%) dose-escalation patients achieved partial response, and 10 (11%) expansion patients achieved partial response or complete response.

CONCLUSIONS

The combination of navoximod and atezolizumab demonstrated acceptable safety, tolerability, and pharmacokinetics for patients with advanced cancer. Although activity was observed, there was no clear evidence of benefit from adding navoximod to atezolizumab.

Phase Ia study of the indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor navoximod (GDC-0919) in patients with recurrent advanced solid tumors

BACKGROUND

Indoleamine-2,3-dioxygenase 1 (IDO1) catalyzes the oxidation of tryptophan into kynurenine and is partially responsible for acquired immune tolerance associated with cancer. The IDO1 small molecule inhibitor navoximod (GDC-0919, NLG-919) is active as a combination therapy in multiple tumor models.

METHODS

This open-label Phase Ia study assessed safety, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary anti-tumor activity of navoximod in patients with recurrent/advanced solid tumors, administered as 50-800 mg BID on a 21/28 day and at 600 mg on a 28/28 day schedule. Plasma kynurenine and tryptophan were longitudinally evaluated and tumor assessments were performed.

RESULTS

Patients (n = 22) received a median of 3 cycles of navoximod. No maximum tolerated dose was reached. One dose-limiting toxicity of Grade 4 lower gastrointestinal hemorrhage was reported. Adverse events (AEs) regardless of causality in ≥20% of patients included fatigue (59%), cough, decreased appetite, and pruritus (41% each), nausea (36%), and vomiting (27%). Grade ≥ 3 AEs occurred in 14/22 patients (64%), and were related to navoximod in two patients (9%). Navoximod was rapidly absorbed (Tmax ~ 1 h) and exhibited dose-proportional increases in exposure, with a half-life (t1/2 ~ 11 h) supportive of BID dosing. Navoximod transiently decreased plasma kynurenine from baseline levels with kinetics consistent with its half-life. Of efficacy-evaluable patients, 8 (36%) had stable disease and 10 (46%) had progressive disease.

CONCLUSIONS

Navoximod was well-tolerated at doses up to 800 mg BID decreasing plasma kynurenine levels consistent with its half-life. Stable disease responses were observed.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02048709 .

A Phase Ib Dose-Escalation Study of the Safety, Tolerability, and Pharmacokinetics of Cobimetinib and Duligotuzumab in Patients with Previously Treated Locally Advanced or Metastatic Cancers with Mutant KRAS

Lessons Learned.

Cobimetinib and duligotuzumab were well tolerated as single agents and in combination with other agents.

The cobimetinib and duligotuzumab combination was associated with increased toxicity, most notably gastrointestinal, and limited efficacy in the patient population tested.

Background.

KRAS‐mutant tumors possess abnormal mitogen‐activated protein kinases (MAPK) pathway signaling, leading to dysregulated cell proliferation. Cobimetinib blocks MAPK signaling. The dual‐action antibody duligotuzumab (MEHD7945A) inhibits ligand binding to both epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 3 (HER3). Blockade of EGFR/HER3 and inhibition of mitogen‐activated protein kinase (MEK) in KRAS‐mutant tumors may provide additive benefit.

Methods.

Patients with KRAS‐mutant solid tumors were eligible for this phase Ib dose‐escalation study with a planned expansion phase. Duligotuzumab was given intravenously (IV) at 1,100 mg every 2 weeks (q2w), while cobimetinib was given orally in a standard 3 + 3 design to identify the recommended phase II dose (RP2D). The primary objective was to evaluate the safety and tolerability of this combination.

Results.

Twenty‐three patients were enrolled. Dose‐limiting toxicities (DLTs) included grade 4 hypokalemia and grade 3 mucosal inflammation, asthenia, and dermatitis acneiform. Seventy percent of patients experienced grade 3 or worse adverse events (AEs). Five (22%) and 12 (52%) patients missed at least 1 dose of duligotuzumab and cobimetinib, respectively, and 9 (39%) patients required a cobimetinib dose reduction. Three (13%) patients discontinued due to an AE. Best response was limited to 9 patients with stable disease and 13 patients with progressive disease.

Conclusion.

Given the limited tolerability and efficacy of this combination, the study did not proceed to expansion stage and closed for enrollment.

A phase Ib dose escalation study of combined inhibition of IDO1 (GDC-0919) and PD-L1 (atezolizumab) in patients (pts) with locally advanced or metastatic solid tumors

105

Background: GDC-0919, a small molecule inhibitor of indoleamine-2,3-dioxygenase 1 (IDO1), reduces tryptophan catabolism and kynurenine production within the tumor microenvironment that may promote normal effector T cell activity and an immunogenic state. IDO1 inhibition may complement targeting of PD-L1 with atezolizumab. Methods: A Phase Ib, open-label, study assessed safety, pharmacokinetics (PK), pharmacodynamics (PD), and anti-tumor activity (RECIST v1.1) of GDC-0919 and atezolizumab in pts with locally advanced or metastatic solid tumors. Pts were given escalating doses of GDC-0919 (50-1000 mg orally twice daily, for 21 days) and atezolizumab (1200 mg IV, every 3 weeks) using a standard 3+3 design. Results: As of 14Dec2016, 52 pts were treated in 6 cohorts of GDC-0919 plus atezolizumab. The median number of prior systemic therapies was 3 (range 1-9); 2 pts received prior immunotherapy. Pts received a median of 4 cycles of GDC-0919 and atezolizumab (range 1-17). No MTD was identified. Across all dose levels, 1 DLT was observed (Grade [G] 3 sepsis syndrome at GDC-0919 200 mg); no G4/5 AEs were attributed to study treatment. G3+ AEs, regardless of causality were reported in 34 (65%) pts. Related G3 AEs were reported in 7 (13%) pts, included nausea, rash, sepsis syndrome, fatigue, and pneumonitis. Two pts (4%) had AEs leading to treatment discontinuation, related in 1/2 (G3 pneumonitis). Combination PK was consistent with single agent observations and supports BID dosing of GDC-0919. Peripheral PD showed dose-dependent decreases in plasma kynurenine, consistent with systemic modulation of IDO1. Preliminary efficacy data from 45 pts with ≥ 1 on-treatment tumor assessments included 4 patients (9%) with partial response and 11 (24%) pts with stable disease. Conclusions: The combination of GDC-0919 and atezolizumab was generally well-tolerated and demonstrated peripheral IDO1 modulation and preliminary efficacy in a heterogeneous patient population during dose escalation. The study is currently enrolling pts with select tumor types in expansion cohorts to assess tumor PD and combination efficacy. Clinical trial information: NCT02471846.

Clinical translation of ferumoxytol-based vessel size imaging (VSI): Feasibility in a phase I oncology clinical trial population

PURPOSE

To assess the feasibility of acquiring vessel size imaging (VSI) metrics using ferumoxytol injections and stock pulse sequences in a multicenter Phase I trial of a novel therapy in patients with advanced metastatic disease.

METHODS

Scans were acquired before, immediately after, and 48 h after injection, at screening and after 2 weeks of treatment. ΔR2 , ΔR2*, vessel density (Q), and relative vascular volume fractions (VVF) were estimated in both normal tissue and tumor, and compared with model-derived theoretical and experimental estimates based on preclinical murine xenograft data.

RESULTS

R2 and R2* relaxation rates were still significantly elevated in tumors and liver 48 h after ferumoxytol injection; liver values returned to baseline by week 2. Q was relatively insensitive to changes in ΔR2*, indicating lack of dependence on contrast agent concentration. Variability in Q was higher among human tumors compared with xenografts and was mostly driven by ΔR2 . Relative VVFs were higher in human tumors compared with xenografts, while values in muscle were similar between species.

CONCLUSION

Clinical ferumoxytol-based VSI is feasible using standard MRI techniques in a multicenter study of patients with lesions outside of the brain. Ferumoxytol accumulation in the liver does not preclude measurement of VSI parameters in liver metastases. Magn Reson Med 77:814-825, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Randomized Phase II Study of Duligotuzumab (MEHD7945A) vs. Cetuximab in Squamous Cell Carcinoma of the Head and Neck (MEHGAN Study)

Background

Duligotuzumab, a novel dual-action humanized IgG1 antibody that blocks ligand binding to epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 3 (HER3), inhibits signaling from all ligand-dependent HER dimers, and can elicit antibody-dependent cell-mediated cytotoxicity. High tumor-expression of neuregulin 1 (NRG1), a ligand to HER3, may enhance sensitivity to duligotuzumab.

Methods

This multicenter, open-label, randomized phase II study (MEHGAN) evaluated drug efficacy in patients with recurrent/metastatic (R/M) squamous cell carcinoma of the head and neck (SCCHN) progressive on/after chemotherapy and among patients with NRG1-high tumors. Patients received duligotuzumab (1100 mg IV, q2w) or cetuximab (400 mg/m² load, 250 mg/m² IV, q1w) until progression or intolerable toxicity. Tumor samples were assayed for biomarkers [NRG1, ERBB3, and human papillomavirus (HPV) status].

Results

Patients (N = 121) were randomized (duligotuzumab:cetuximab; 59:62), median age 62 years; ECOG 0–2. Both arms (duligotuzumab vs. cetuximab, respectively) showed comparable progression-free survival [4.2 vs. 4.0 months; HR: 1.23 (90% confidence interval (CI): 0.89–1.70)], overall survival [7.2 vs. 8.7 months; HR 1.15 (90% CI: 0.81–1.63)], and objective response rate (12 vs. 14.5%), with no difference between patients with NRG1-high tumors or ERBB3-low tumors. Responses in both arms were confined to HPV-negative patients. Grade ≥3 adverse events (AEs) (duligotuzumab vs. cetuximab, respectively) included infections (22 vs. 11.5%) and GI disorders (17 vs. 7%), contributing to higher rates of serious AEs (41 vs. 29.5%). Metabolic disorders were less frequent with duligotuzumab (10 vs. 16%); any grade rash-related events were less with duligotuzumab (49 vs. 67%).

Conclusion

While several lines of preclinical evidence had supported the premise that the blockade of HER3 in addition to that of EGFR may improve outcomes for patients with R/M SCCHN overall or specifically in those patients whose tumors express high levels of NRG1, this study provided definitive clinical evidence refuting this hypothesis. Duligotuzumab did not improve patient outcomes in comparison to cetuximab despite frequent expression of NRG1. These data indicate that inhibition of EGFR alone is sufficient to block EGFR–HER3 signaling, suggesting that HER2 plays a minimal role in this disease. Extensive biomarker analyses further show that HPV-negative SCCHN but not HPV-positive SCCHN are most likely to respond to EGFR blockage by cetuximab or duligotuzumab.

Abstract 5155: Integrated genomic analysis of colorectal cancer progression reveals activation of EGFR through demethylation of the EREG promoter

The molecular drivers that underlie transformation of colonic epithelium into colorectal adenocarcinoma (CRC) have been well described. However, the mechanisms through which some of the clinically targeted pathways are activated during CRC progression have yet to be elucidated. Here, we employed an integrative genomics approach to examine CRC progression. Transcriptional profiling of laser capture microdissected colonic crypt cells, differentiated surface epithelium, adenomas, carcinomas, and metastases, showed distinctive patterns in the activation of developmental and oncogenic pathways, including the clinically important EGFR axis. We observed a dramatic up-regulation of the EGFR ligand EREG in primary and metastatic cancer cells as compared to normal and adenomatous tissues that was indicative of autocrine tumor production, and confirmed this pattern of gene expression by in situ hybridization. Global methylation analysis indicated that up-regulation of EREG during the adenoma-carcinoma transition was associated with de-methylation of two key sites within the EREG promoter and this was accompanied by an increase in the levels of EGFR phosphorylation, as assessed by reverse phase protein analysis. In a clinical trial setting, we observed that low levels of EREG methylation in patients who received cetuximab as part of a Phase II study were associated with high expression of the ligand and a favorable response to therapy. Conversely, high levels of promoter methylation and low levels of EREG expression were observed in tumors that progressed after treatment. We also noted an inverse correlation between EREG methylation and expression levels in several other cancers from the TCGA datasets, including those of the head and neck, lung, and bladder. We propose that up-regulation of EREG expression through promoter de-methylation might be an important means of activating the EGFR pathway during the genesis of CRC and, potentially, other types of cancer.

Citation Format: Xueping Qu, Thomas Sandmann, Henry Frierson, Ling Fu, Eloisa Fuentes, Kimberly Walter, Kwame Okrah, Craig Rumpel, Christopher Moskaluk, Shan Lu, Yulei Wang, Richard Bourgon, Elicia Penuel, Andrea Pirzkall, Lukas Amler, Mark Lackner, Josep Tabenero, Garret Hampton, Omar Kabbarah. Integrated genomic analysis of colorectal cancer progression reveals activation of EGFR through demethylation of the EREG promoter. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5155.

Safety and Pharmacokinetics/Pharmacodynamics of the First-in-Class Dual Action HER3/EGFR Antibody MEHD7945A in Locally Advanced or Metastatic Epithelial Tumors

PURPOSE

The novel dual-action humanized IgG1 antibody MEHD7945A targeting HER3 and EGFR inhibits ligand-dependent HER dimer signaling. This phase I study evaluated the safety, pharmacokinetics, pharmacodynamics, and antitumor activity of MEHD7945A.

EXPERIMENTAL DESIGN

Patients with locally advanced or metastatic epithelial tumors received escalating doses of MEHD7945A (1-30 mg/kg) every 2 weeks (q2w) until disease progression or intolerable toxicity. An expansion cohort was enrolled at the recommended phase II dose (14 mg/kg, q2w). Plasma samples, tumor biopsies, FDG-PET were obtained for assessment of pharmacokinetics, and pharmacodynamic modulation downstream of EGFR and HER3.

RESULTS

No dose-limiting toxicities or MEHD7945A-related grade ≥ 4 adverse events (AE) were reported in dose-escalation (n = 30) or expansion (n = 36) cohorts. Related grade 3 AEs were limited to diarrhea and nausea in the same patient (30 mg/kg). Related AEs in ≥20% of patients ≤24 hours after the first infusion included grade 1/2 headache, fever, and chills, which were managed with premedication and/or symptomatic treatment. Pharmacodynamic data indicated target inhibition in 25% of evaluable patients. Best response by RECIST included 2 confirmed partial responses in squamous cell carcinomas of head and neck (SCCHN) patients with high tumor tissue levels of the HER3 ligand heregulin; 14 patients had stable disease ≥8 weeks, including SCCHN (n = 3), colorectal cancer (n = 6), and non-small cell lung cancer (n = 3).

CONCLUSIONS

MEHD7945A was well-tolerated as single agent with evidence of tumor pharmacodynamic modulation and antitumor activity in SCCHN. Phase II studies were initiated with flat (nonweight-based) dosing at 1,100 mg q2w in SCCHN and colorectal cancer.

Abstract CT110: Randomized phase II study of duligotuzumab + FOLFIRI versus cetuximab + FOLFIRI in 2nd-line patients with KRAS wild-type (wt) metastatic colorectal cancer (mCRC)

Background: Duligotuzumab (MEHD, MEHD7945A) is a novel dual-action humanized IgG1 antibody that blocks EGFR and HER3 binding, inhibiting all major ligand-dependent HER complex signaling. MEHD is active in multiple tumor models, including models resistant to anti-EGFR or anti-HER3. Emerging data in CRC suggest a role for HER3 in de novo and acquired resistance to anti-EGFR therapy.

Methods: This open-label, randomized Phase II study enrolled patients (pts) with KRAS exon 2 wt mCRC who progressed on/after oxaliplatin-containing chemotherapy. Pts received a combination of MEHD (1100 mg IV, q2w) or cetuximab (400 mg/m2 load, 250 mg/m2 IV, q1w) + FOLFIRI (q2w) until progression or intolerable toxicity. Endpoints included progression-free survival (PFS), and objective response rate (ORR), overall survival (OS), and adverse events (AEs). Tumor samples were mandatory and underwent biomarker analysis for ERBB3, NRG1 and EGFR ligand expression by qRT-PCR, and ERBB3 by IHC. The primary efficacy analysis was conducted in patients with RAS wt tumors (no mutations detected in KRAS or NRAS exons 2, 3; exon 4 mutations pending).

Results: Of 134 randomized patients, 98 were RAS ex2/3 wt (53 MEHD); median age 63 years, ECOG 0-1. As of 21Aug14, 11 pts remain active. Efficacy results (Table) show no benefit of MEHD + FOLFIRI; ORR was lower in the MEDH arm. No relationship was seen between PFS or ORR and mRNA expression for ERBB3 or NRG1, or ERB3 expression by IHC. There were fewer rash events of any grade in the MEHD arm (79% and 93%) but more diarrhea (89% and 66%). Incidence of Grade ≥ 3 AEs was similar between arms (87% and 89%); however, the frequency of SAEs was higher in the MEHD arm (55% and 48%). Cumulative dose intensity and duration of treatment with FOLFIRI were lower in the MEHD arm.

Conclusions: MEHD + FOLFIRI did not improve outcomes of pts with RAS ex2/3 wt mCRC compared to cetuximab + FOLFIRI. Updated efficacy, safety and biomarker data will be presented.

All ptsMEHD7945A + FOLFIRICetuximab + FOLFIRIHazard Ratio or Odds Ratio (90% CI)(n = 53)(n = 45)PFS events39 (74%)33 (73%)1.40 (0.94-2.08)Median PFS, mo (90% CI)6.9 (4.9-7.6)5.7 (5.5-7.7)OS events18 (34%)19 (42%)0.85 (0.49-1.46)Median OS, mo (90% CI)NE (12.0-NE)12.4 (10.0-NE)ORR,% (90% CI)17.0 (9.8-26.6)33.3 (21.8-46.1)0.41 (0.18-0.91)CI = confidence interval. NE = not estimated

Citation Format: Andrew G. Hill, Michael Findlay, Matthew Burge, Christopher Jackson, Pilar Garcia Alfonso, Leslie Samuel, Vinod Ganju, Meinolf Karthaus, Alessio Amatu, Mark Jeffery, Maria DiBartolomeo, John Bridgewater, Andrew Coveler, Manuel Hidalgo, Amy V. Kapp, Roxana Sufan, Bruce McCall, Elicia Penuel, Andrea Pirzkall, Josep Tabernero. Randomized phase II study of duligotuzumab + FOLFIRI versus cetuximab + FOLFIRI in 2nd-line patients with KRAS wild-type (wt) metastatic colorectal cancer (mCRC). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT110. doi:10.1158/1538-7445.AM2015-CT110

Pertuzumab and erlotinib in patients with relapsed non-small cell lung cancer: a phase II study using 18F-fluorodeoxyglucose positron emission tomography/computed tomography imaging

BACKGROUND

Combination blockade of human epidermal growth factor receptor (HER) family signaling may confer enhanced antitumor activity than single-agent blockade. We performed a single-arm study of pertuzumab, a monoclonal antibody that inhibits HER2 dimerization, and erlotinib in relapsed non-small cell lung cancer (NSCLC).

METHODS

Patients received pertuzumab (840-mg loading dose and 420-mg maintenance intravenously every 3 weeks) and erlotinib (150-mg or 100-mg dose orally, daily). The primary endpoint was response rate (RR) by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) at day 56 in all patients and those with EGFR wild-type tumors.

RESULTS

Of 41 patients, 28 (68.3%) experienced treatment-related grade ≥3 adverse events, including pneumatosis intestinalis (3 patients), resulting in early cessation of enrollment. Tissue samples from 32 patients showed mutated EGFR status in 9 of 41 (22%) and wild-type EGFR in 23 of 41 (56%). The FDG-PET RR for patients with assessments at day 56 was 19.5% in all patients (n = 41) and 8.7% in patients with wild-type EGFR NSCLC (n = 23). Investigator-assessed computed tomography RR at day 56 was 12.2%.

CONCLUSION

FDG-PET suggests that pertuzumab plus erlotinib is an active combination, but combination therapy was poorly tolerated, which limits its clinical applicability. More research is warranted to identify drug combinations that disrupt HER receptor signaling but that exhibit improved tolerability profiles.

Abstract 3363: Pharmacodynamic (PD) assessment of drug activity in tumor tissue from patients (pts) enrolled in a Phase I study of MEHD7945A (MEHD), a first-in-class HER3/EGFR dual action antibody, in pts with locally advanced or metastatic epithelial tumors

Background

Members of the human epidermal growth factor receptor (HER) family of oncogenes are often co-expressed and heterodimerized, suggesting that simultaneous blockade of multiple HER family receptors may be more effective than targeting single receptors. MEHD is a dual-action human IgG1 antibody that can bivalently bind to HER3 and EGFR and block ligand binding to either. FDG-PET imaging is a recognized method of assessing PD modulation with EGFR inhibitors in the clinic. HER3 and EGFR signaling via the MAPK and PI3K pathways can be monitored in tissue by examining phosphorylation of downstream markers.

Methods

A Phase 1, multicenter, open-label study was conducted to evaluate the safety, pharmacokinetics, and anti-tumor activity of MEHD administered intravenously every 2 weeks at doses ranging from 1 to 30 mg/kg during escalation (n=30), and at 14 mg/kg during expansion (n=36). FDG-PET scans and optional tumor biopsies (bxs) were obtained at baseline and cycle 2, day 2 (C2D2). Tumor bxs were evaluated by immunohistochemistry (IHC) for S235/236-p-S6, T246-p-PRAS40, and T202/Y204-p-MAPK. EGFR and KRAS mutation (mt) status was determined by PCR. Paired frozen bxs were utilized for exploratory assessment by reverse-phase protein arrays (see Penuel et al. abstract).

Results

Evidence of PD modulation by imaging or IHC was observed in 14 pts including 7 CRC (KRAS mt-2, wt-5), 3 NSCLC, 2 SCCHN, 1 ovarian, and 1 anal cancer. Tumor FDG-uptake was decreased by at least 20%, indicating a partial metabolic response (PMR), in 9/56 evaluated pts (16%). Tumor bxs were obtained at baseline and C2D2 from 32 pts (12 escalation, 20 expansion). Sufficient viable tumor for IHC was present in both bxs from 17/32 evaluated pts. IHC signal was decreased for one or more of the 3 markers in the C2D2 bxs of 6/17 pts (35%), 5 CRC (KRAS mt-2, wt-3), 1 NSCLC. Best response by CT-RECIST includes PR in 2 patients with SCCHN, both with PMR and both tumors expressing high heregulin, with duration of response of 10 and 12+ months.

Conclusions

Evidence of PD modulation is demonstrated by a PMR rate of 16% and reduced pathway activity by IHC in 35% of pts with evaluable biopsies. These data suggest MEHD is biologically active in pts and downregulates intracellular signaling activity consistent with HER3 and/or EGFR inhibition in tumor tissue and is further supported by evidence of anti-tumor activity. Phase II studies in SCCHN and CRC are ongoing.

Citation Format: Dejan Juric, Rodrigo Dienstmann, Andres Cervantes, Manuel Hidalgo, Wells Messersmith, George Blumenschein, Jose Baselga, Josep Tabernero, Desamparados Roda, Antonio Calles, Antonio Jimeno, Lukas Amler, Howard Stern, Sandra Sanabria, Elicia Penuel, Andrea Pirzkall. Pharmacodynamic (PD) assessment of drug activity in tumor tissue from patients (pts) enrolled in a Phase I study of MEHD7945A (MEHD), a first-in-class HER3/EGFR dual action antibody, in pts with locally advanced or metastatic epithelial tumors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3363. doi:10.1158/1538-7445.AM2013-3363

Abstract 3527: Assessing signal modulation in preclinical models and tumor tissue from patients enrolled in a Phase 1 study of the HER3/EGFR dual action antibody, MEHD7945A (MEHD), as an exploratory pharmacodynamic (PD) analysis

Background

Aberrant activation of HER family members including EGFR results in unregulated proliferative signals involved in tumorigenesis. HER3 plays a unique role as both a dimerization-dependent allosteric catalyst and critical activator of PI3 kinase signaling (PI3K). MEHD is a dual-action antibody that blocks ligand binding to EGFR and HER3 to abrogate signaling downstream from these two receptors. Early clinical evidence shows PD modulation and biological activity. The two major signaling pathways activated by ligand binding to these receptors are the RAS/MAPK and PI3K/AKT pathways. Phosphorylation of these critical signaling proteins can be monitored to evaluate inhibition of ligand driven receptor activity.

Methods

Phosphorylation of signaling proteins in the RAS/MAPK and PI3K/AKT pathways was measured by Western blot analysis and reverse-phase protein arrays (RPPA) in MEHD-sensitive cell lines and xenograft models. Paired tumor biopsies from patients in the Phase 1 MEHD study were collected pre and post MEHD dosing. Half of each sample was formalin-fixed and paraffin-embedded for immunohistochemistry (IHC) using pS6 (S235/236), pPRAS40 (T246), and pMAPK (T202/Y204); the other half was frozen and embedded in Optimum Cutting Temperature compound (OCT) for analysis of multiple signaling pathway endpoints by RPPA.

Results

Inhibition of EGFR and/or HER3 activated signaling by MEHD was confirmed in sensitive cell lines and xenograft models by western blot analysis for key analytes including pMAPK and pS6. Broader analysis of signaling in the RAS/MAPK and PI3K/AKT pathways by RPPA demonstrated additional markers that were inhibited by MEHD. Signaling from EGFR driven models was blocked by EGFR inhibition alone but signaling in models in which both EGFR and HER3 were contributing factors, as assessed by tumor growth inhibition, were not inhibited by EGFR inhibition alone. However, MEHD was equally effective at blocking signaling in both models. Analytes that were inhibited by MEHD in these pre-clinical models were measured by RPPA and IHC in paired biopsy specimens from the Ph1 MEHD study as a PD assessment. Thirty-two paired biopsies were obtained. 20/32 had sufficient tissue and tumor for assessment and 11/20 showed decreased phosphorylation of pERK, pPRAS40, or pS6 by IHC and/or RPPA.

Conclusions

Preclinical evaluation of RAS/MAPK and PI3K/AKT signaling in MEHD-sensitive cell lines and xenograft models identified pERK, pPRAS40, and pS6 as measurable indicators of MEHD target engagement and biological activity. Evaluation of these markers in patient tumor biopsies demonstrated that signaling pathways consistent with HER3 and/or EGFR inhibition are downregulated in tumors, suggesting that MEHD is biologically active in patients (see Juric et al., AACR abstract).

Citation Format: Elicia M. Penuel, Luciana Burton, Howard Stern, Lackner Mark, Andrea Pirzkall, Lukas Amler, Gabriele Schaefer. Assessing signal modulation in preclinical models and tumor tissue from patients enrolled in a Phase 1 study of the HER3/EGFR dual action antibody, MEHD7945A (MEHD), as an exploratory pharmacodynamic (PD) analysis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3527. doi:10.1158/1538-7445.AM2013-3527

High heregulin expression is associated with activated HER3 and may define an actionable biomarker in patients with squamous cell carcinomas of the head and neck

PURPOSE

Tumors with oncogenic dependencies on the HER family of receptor tyrosine kinases (RTKs) often respond well to targeted inhibition. Our previous work suggested that many cell lines derived from squamous cell carcinomas of the head and neck (SCCHNs) depend on autocrine signaling driven by HER2/3 dimerization and high-level co-expression of HRG. Additionally, results from a Phase I trial of MEHD7495A, a dual-action antibody that blocks ligand binding to EGFR and HER3, suggest that high-level HRG expression was associated with clinical response in SCCHN patients. Here we explore the hypothesis that high-level HRG expression defines a subpopulation of SCCHNs with activated HER3.

EXPERIMENTAL DESIGN

qRT-PCR expression profiling was performed on >750 tumors of diverse origin, including >150 therapy-naïve, primary, and recurrent SCCHNs. Activated HER3, defined by immunoprecipitation of phospho-HER3, was compared to HRG expression in SCCHN samples. Paracrine versus autocrine expression was evaluated using RNA-in situ hybridization.

RESULTS

SCCHN tumors express the highest levels of HRG compared to a diverse collection of other tumor types. We show that high HRG expression is associated with activated HER3, whereas low HRG expression is associated with low HER3 activation in SCCHN tumors. Furthermore, HRG expression is higher in recurrent SCCHN compared to patient-matched therapy naïve specimens.

CONCLUSIONS

HRG expression levels define a biologically distinct subset of SCCHN patients. We propose that high-level expression of HRG is associated with constitutive activation of HER3 in SCCHN and thus defines an actionable biomarker for interventions targeting HER3.

A phase I study of MEHD7945A (MEHD), a first-in-class HER3/EGFR dual-action antibody, in patients (pts) with refractory/recurrent epithelial tumors: Expansion cohorts

2568

Background: Dysregulated human epidermal growth factor receptor tyrosine kinase (HER RTK) signaling is an important driver of tumor growth, metastasis, and survival. Extensive co-expression and heterodimerization suggest that simultaneous blockade of multiple HER RTKs may be more effective than blockade of a single RTK. MEHD is a novel dual-action human IgG1 antibody. Each antigen-binding fragment blocks ligand binding to HER3 or EGFR, and intended to inhibit signaling from all major ligand-dependent HER dimers. MEHD has single-agent activity in multiple tumor models including models resistant to anti-HER3 or anti-EGFR. Methods: This Phase I study evaluated safety, tolerability, pharmacokinetics (PK), and pharmacodynamic (PD) activity of intravenous MEHD every 2 weeks (q2w). Tumor PD assessments were pre- and post-dose FDG-PET and IHC for pS6, pPRAS40 or pERK in tumor biopsies. Tumor CT assessments were performed q8w. No dose-limiting toxicity (DLT) was observed in six 3+3 cohorts from 1-30 mg/kg (n=30). We report results from 4 tumor-specific cohorts receiving 14 mg/kg MEHD (recommended Phase II dose). Results: As of 21 Nov 2011, 36 pts (CRC=12, NSCLC=9, SCCHN=10, pancreatic=5), median age 62.5 (35–87), all PS 0-1, median # prior regimens 3.5 (1-8), received a median of 4 doses (1-9) of MEHD; 18 pts remain on study. PK data are consistent with human anti-EGFR antibodies. No related Grade (G) ≥3 adverse events (AEs) have been observed. Common related G1/2 AEs included rash/dermatitis (53%), diarrhea (36%), fatigue (22%), paronychia (19%), dry skin, nausea, and decreased appetite (all 17%), asthenia and stomatitis/oral pain (all 14%). Related AEs ≤ 24 h after first infusion included G1/2 headache (42%), fever (33%), and chills (17%), and decreased in intensity and frequency with later infusions. Early PD data indicate target inhibition in 8/36 pts (SCCHN=2, NSCLC=2, CRC=4), and best response by RECIST includes 2 PR (both SCCHN), 6 pts with SD ≥ 8 weeks (NSCLC=2, CRC=4), 7/8 previously treated with EGFR inhibitors. Conclusions: MEHD at 14 mg/kg q2w has an encouraging safety profile and evidence of anti-tumor activity. Phase II studies are planned.

Identification of head and neck cancers (SCCHN) that may respond to dual inhibition of EGFR and HER3 signaling

5575

Background: Oncogenic signaling through the epidermal growth factor receptor family is one of the most frequent alterations found in human epithelial cancers. These receptor tyrosine kinases mediate their effects via high-level co-expression and homo- and heterodimerization events that drive tumor growth, metastasis, and survival. Extensive preclinical studies suggested that some cell lines depend on oncogenic autocrine signaling through HER3 (Wilson et al.). This phenotype was particularly prominent in cell lines derived from SCCHN and was strongly correlated with high HRG expression. Interestingly, two patients with SCCHN tumors that expressed high levels of HRG in our phase Ia trial (abstract #95245) of MEHD7954A, a dual-action human IgG1 antibody that blocks ligand binding to EGFR and HER3 (Schaefer et al.) had partial responses. To further explore the hypothesis that high-level HRG expression defines a sub-population of SCCHN that may be sensitive to agents targeting HER3, and to identify other potential target indications for the development of MEHD7954A, we evaluated the expression of HRG in large cohorts of multiple solid tumor indications. Methods: HER3 and HRG expression was analyzed by qRT-PCR in 648 formalin-fixed paraffin embedded primary tumor samples from patients with NSCLC, SCCHN, melanoma, CRC and triple-negative breast cancer. Results: SCCHN-derived tumor samples had the highest levels of HRG expression, exhibiting a bimodal distribution in SCCHN – a pattern that is clearly distinct when compared to other tumor types. These data suggest that high HRG levels and potentially HER3-dependent autocrine signaling occur more frequently in SCCHN than in other tumors. Further we investigated whether overexpression of HRG in SCCHN correlated with stage and disease outcome. Updated results from these extended studies will be presented. Conclusions: SCCHN tumors exhibit bimodal expression of HRG, suggesting that HRG expression levels may be useful in identifying a subset of patients most likely to benefit from inhibition of HER3 activity. Antitumor activity in such patients has been observed in a phase I study of MEHD7954A (abstract #95245).

Human pharmacokinetic (PK) characterization of the novel dual-action anti-HER3/EGFR antibody MEHD7945A (MEHD) in patients with refractory/recurrent epithelial tumors

2567

Background: MEHD is a novel dual-action human IgG1 antibody that blocks ligand binding to HER3 and EGFR, and elicits antibody-dependent cell-mediated cytotoxicity (ADCC). MEHD demonstrates single-agent activity in a broad panel of tumor models, including models resistant to anti-HER3 or anti-EGFR treatment alone. The objective of this analysis was to characterize the PK of MEHD associated with body weight (BW)-based dosing used in a phase I study in patients with epithelial tumors and to evaluate the potential for using fixed dosing in future studies. Methods: Preliminary non-compartmental and population PK analyses were performed using patient data from the dose-escalation stage [1, 4, 10, 15, 22, and 30 mg/kg every two weeks (q2w)] and expansion stage (14 mg/kg q2w) of the phase I study. Patient demographic data and other relevant clinical covariates were evaluated in the population analysis. PK simulation of 1000 subjects with a log-normal BW distribution was performed to compare the inter-individual variability of MEHD exposure following fixed or BW-based dosing. Results: As expected,MEHD exhibited nonlinear PK. In the noncompartmenal analysis, the apparent clearance (CL) decreased in a dose-dependent fashion (about 40 to 9.9 mL/day/kg from 1 to 30 mg/kg) and approached linearity at doses >10 mg/kg (q2w). In the population analysis, the PK profile of MEHD was well described by a two compartment model with linear and nonlinear clearance. The target-mediated clearance was consistent with that of anti-EGFR antibodies. The nonspecific CL and central volume of distribution (V1) values were approximately 6 mL/day/kg and 52.4 mL/kg, respectively. BW had a moderate effect on V1, but not on CL. PK simulations suggest that, compared with BW-based dosing, fixed dosing would result in less inter-individual variability in MEHD exposure. Both 1100 mg q2w or 1650 mg q3w of MEHD achieve the targeted therapeutic exposure. Conclusions: The dual-action antibody MEHD demonstrated PK consistent with anti-EGFR antibodies. Fixed dosing of MEHD on an every 2 or 3 week schedule is supported.

Evaluation of circulating tumor cells and circulating tumor DNA in non-small cell lung cancer: association with clinical endpoints in a phase II clinical trial of pertuzumab and erlotinib

PURPOSE

Elevated levels or increases in circulating tumor cells (CTC) portend poor prognosis in patients with epithelial cancers. Less is known about CTCs as surrogate endpoints or their use for predictive biomarker evaluation. This study investigated the utility of CTC enumeration and characterization using the CellSearch platform, as well as mutation detection in circulating tumor DNA (ctDNA), in patients with advanced non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

Forty-one patients were enrolled in a single-arm phase II clinical trial of erlotinib and pertuzumab. Peripheral blood was analyzed for CTC enumeration, EGFR expression in CTCs, and detection of oncogenic mutations in CTCs and ctDNA. Changes in CTC levels were correlated with 2[18F]fluoro-2-deoxy-D-glucose-positron emission tomographic (FDG-PET) and computed tomographic (CT) imaging and survival endpoints.

RESULTS

CTCs were detected (≥ 1 CTC) at baseline in 78% of patients. Greater sensitivity for mutation detection was observed in ctDNA than in CTCs and detected mutations were strongly concordant with mutation status in matched tumor. Higher baseline CTC counts were associated with response to treatment by Response Evaluation Criteria in Solid Tumors (RECIST, P = 0.009) and decreased CTC counts upon treatment were associated with FDG-PET and RECIST response (P = 0.014 and P = 0.019) and longer progression-free survival (P = 0.050).

CONCLUSION

These data provide evidence of a correlation between decreases in CTC counts and radiographic response by either FDG-PET or RECIST in patients with advanced NSCLC. These findings require prospective validation but suggest a potential role for using CTC decreases as an early indication of response to therapy and ctDNA for real-time assessment of mutation status from blood.

Changes in 18F-fluorodeoxyglucose and 18F-fluorodeoxythymidine positron emission tomography imaging in patients with non-small cell lung cancer treated with erlotinib

PURPOSE

Assessing clinical activity of molecularly targeted anticancer agents, especially in the absence of tumor shrinkage, is challenging. To evaluate on-treatment 18F-fluorodeoxyglucose (FDG) and/or 18F-fluorodeoxythymidine (FLT) positron emission tomography (PET) for this purpose, we conducted a prospective multicenter trial assessing PET response rates and associations with progression-free (PFS) and overall survival (OS) in 2nd/3rd-line non-small-cell lung cancer patients treated with erlotinib.

EXPERIMENTAL DESIGN

PET/computed tomography (CT) scans were conducted at baseline, day (d)14 and d56 after the first daily erlotinib dose, with diagnostic CT at baseline and d56 (all scans centrally reviewed). PET partial metabolic response (PMR) was defined as a mean decrease (in ≤ 5 lesions/patient) of 15% or more maximum standardized uptake value. PFS was investigator-determined.

RESULTS

Of 74 erlotinib-treated patients, 51 completed all imaging assessments through d56; 13 of 51 (26%) FDG-evaluable patients had PMR at d14, as did 9 of 50 (18%) FLT-evaluable patients. Four (7.8%) showed partial responses (PR) by d56 CT; all 4 had PMR by d14 FDG-PET with 3 PMRs by d14 FLT-PET. Three of the 4 patients with CT PR had evaluable archival tumor tissue; all 3 had epidermal growth factor receptor mutations. D14 and d56 PMRs by FDG or FLT were associated with improved PFS; HRs for PET responders versus nonresponders were 0.3 to 0.4. D14 FDG-PET PMR was associated with improved OS (P = 0.03) compared with FDG-PET nonresponders.

CONCLUSION

Early (d14) FDG-PET PMR is associated with improved PFS and OS, even in the absence of subsequent Response Evaluation Criteria in Solid Tumors response. These data support inclusion of FDG-PET imaging in clinical trials testing novel targeted therapies, particularly those with anticipated cytostatic effects.

Molecular biomarker analyses using circulating tumor cells

Background

Evaluation of cancer biomarkers from blood could significantly enable biomarker assessment by providing a relatively non-invasive source of representative tumor material. Circulating Tumor Cells (CTCs) isolated from blood of metastatic cancer patients hold significant promise in this regard.

Methodology/Principal Findings

Using spiked tumor-cells we evaluated CTC capture on different CTC technology platforms, including CellSearch® and two biochip platforms, and used the isolated CTCs to develop and optimize assays for molecular characterization of CTCs. We report similar performance for the various platforms tested in capturing CTCs, and find that capture efficiency is dependent on the level of EpCAM expression. We demonstrate that captured CTCs are amenable to biomarker analyses such as HER2 status, qRT-PCR for breast cancer subtype markers, KRAS mutation detection, and EGFR staining by immunofluorescence (IF). We quantify cell surface expression of EGFR in metastatic lung cancer patient samples. In addition, we determined HER2 status by IF and FISH in CTCs from metastatic breast cancer patients. In the majority of patients (89%) we found concordance with HER2 status from patient tumor tissue, though in a subset of patients (11%), HER2 status in CTCs differed from that observed in the primary tumor. Surprisingly, we found CTC counts to be higher in ER+ patients in comparison to HER2+ and triple negative patients, which could be explained by low EpCAM expression and a more mesenchymal phenotype of tumors belonging to the basal-like molecular subtype of breast cancer.

Conclusions/Significance

Our data suggests that molecular characterization from captured CTCs is possible and can potentially provide real-time information on biomarker status. In this regard, CTCs hold significant promise as a source of tumor material to facilitate clinical biomarker evaluation. However, limitations exist from a purely EpCAM based capture system and addition of antibodies to mesenchymal markers could further improve CTC capture efficiency to enable routine biomarker analysis from CTCs.

Ex vivo MR spectroscopic measure differentiates tumor from treatment effects in GBM

The motivation of this study was to address the urgent clinical problem related to the inability of magnetic resonance (MR) imaging measures to differentiate tumor progression from treatment effects in patients with glioblastoma multiforme (GBM). While contrast enhancement on MR imaging (MRI) is routinely used for assessment of tumor burden, therapy response, and progression-free survival in GBM, it is well known that changes in enhancement following treatment are nonspecific to tumor. To address this issue, the objective of this study was to investigate whether MR spectroscopy can provide improved biomarker surrogates for tumor following treatment. High-resolution metabolic profiles of tissue samples obtained from patients with GBM were directly correlated with their pathological assessment to determine metabolic markers that correspond to pathological indications of tumor or treatment effects. Acquisition of tissue samples with image guidance enabled the association of ex vivo biochemical and pathological properties of the tissue samples with in vivo MR anatomical and structural properties derived from presurgical MR images. Using this approach, we found that metabolic concentration levels of [Myo-inositol/total choline (MCI)] in tissue samples are able to differentiate tumor from nontumor and treatment-induced reactive astrocytosis with high significance (P < .001) in newly diagnosed and recurrent GBM. The MCI index has a sensitivity of 93% to tumor in recurrent GBM and delineates the contribution of cellularity that originates from tumor and astrocytic proliferation following treatment. Low levels of MCI for tumor were associated with a reduced apparent diffusion coefficient and elevated choline-N-acetyl-aspartate index derived from in vivo MR images.

Tumor regrowth between surgery and initiation of adjuvant therapy in patients with newly diagnosed glioblastoma

To assess incidence and degree of regrowth in glioblastoma between surgery and radiation therapy (RT) and to correlate regrowth with presurgical imaging and survival, we examined images of 32 patients with newly diagnosed glioblastoma who underwent MR spectroscopic imaging (MRSI), perfusion-weighted imaging (PWI), and diffusion-weighted imaging (DWI) prior to surgery, after surgery, and prior to RT/temozolomide. Contrast enhancement (CE) in the pre-RT MR image was compared with postsurgical DWI to differentiate tumor growth from postsurgical infarct. MRSI and PWI parameters were analyzed prior to surgery and pre-RT. Postsurgical MRI indicated that 18 patients had gross total and 14 subtotal resections. Twenty-one patients showed reduced diffusion, and 25 patients showed new or increased CE. In eight patients (25%), the new CE was confined to areas of postsurgical reduced diffusion. In the other 17 patients (53%), new CE was found to be indicative of tumor growth or a combination of tumor growth and surgical injury. Higher perfusion and creatine within nonenhancing tumor in the presurgery MR were associated with subsequent tumor growth. High levels of choline and reduced diffusion in pre-RT CE suggested active metabolism and tumor cell proliferation. Median survival was 14.6 months in patients with interim tumor growth and 24 months in patients with no growth. Increased volume or new onset of CE between surgery and RT was attributed to tumor growth in 53% of patients and was associated with shorter survival. This suggests that reducing the time between surgery and adjuvant therapy may be important. The acquisition of metabolic and physiologic imaging data prior to adjuvant therapy may also be valuable in assessing regions of new CE and nonenhancing tumor.

Relationship of pre-surgery metabolic and physiological MR imaging parameters to survival for patients with untreated GBM

Glioblastoma Multiforme (GBM) are heterogeneous lesions, both in terms of their appearance on anatomic images and their response to therapy. The goal of this study was to evaluate the prognostic value of parameters derived from physiological and metabolic images of these lesions. Fifty-six patients with GBM were scanned immediately before surgical resection using conventional anatomical MR imaging and, where possible, perfusion-weighted imaging, diffusion-weighted imaging, and proton MR spectroscopic imaging. The median survival time was 517 days, with 15 patients censored. Absolute anatomic lesion volumes were not associated with survival but patients for whom the combined volume of contrast enhancement and necrosis was a large percentage of the T2 hyperintense lesion had relatively poor survival. Other volumetric parameters linked with less favorable survival were the volume of the region with elevated choline to N-acetylaspartate index (CNI) and the volume within the T2 lesion that had apparent diffusion coefficient (ADC) less than 1.5 times that in white matter. Intensity parameters associated with survival were the maximum and the sum of levels of lactate and of lipid within the CNI lesion, as well as the magnitude of the 10th percentile of the normalized ADC within the contrast-enhancing lesion. Patients whose imaging parameters indicating that lesions with a relatively large percentage with breakdown of the blood brain barrier or necrosis, large regions with abnormal metabolism or areas with restricted diffusion have relatively poor survival. These parameters may provide useful information for predicting outcome and for the stratification of patients into high or low risk groups for clinical trials.

Potential value of MR spectroscopic imaging for the radiosurgical management of patients with recurrent high-grade gliomas

Previous studies have shown that metabolic information provided by 3D Magnetic Resonance Spectroscopy Imaging (MRSI) could affect the definition of target volumes for radiation treatments (RT). This study aimed to (i) investigate the effect of incorporating spectroscopic volumes as determined by MRSI on target volume definition, patient selection eligibility, and dose prescription for stereotactic radiosurgery treatment planning; (ii) correlate the spatial extent of pre-SRS spectroscopic abnormality and treatment volumes with areas of focal recurrence as defined by changes in contrast enhancement; and (iii) examine the metabolic changes following SRS to assess treatment response. Twenty-six patients treated with Gamma Knife radiosurgery for recurrent glioblastoma multiforme (GBM) were retrospectively evaluated. All patients underwent both MRI and MRSI studies prior to SRS. Follow-up MRI exams were available for all 26 patients, with MRI/MRSI available in only 15/26 patients. We observed that the initial CNI 2 contours extended beyond the pre-SRS CE in 25/26 patients ranging in volume from 0.8 cc to 18.8 cc (median 5.6 cc). The inclusion of the volume of CNI 2 extending beyond the CE would have increased the SRS target volume by 5-165% (median 23.4%). This would have necessitated decreasing the SRS prescription dose in 19/26 patients to avoid increased toxicity; the resultant treatment volume would have exceeded 20cc in five patients, thus possibly excluding those from RS treatment per our institutional practice. MRSI follow-up studies showed a decrease in Choline, stable Creatine, and increased NAA indicative of response to SRS in the majority of patients. When combined with patient survival data, metabolic information obtained during follow-up MRSI studies seemed to indicate the potential to help to distinguish necrosis from new/recurrent tumor; however, this should be further verified by biopsy studies.

Patterns of recurrence analysis in newly diagnosed glioblastoma multiforme after three-dimensional conformal radiation therapy with respect to pre-radiation therapy magnetic resonance spectroscopic findings

PURPOSE

To determine whether the combined magnetic resonance imaging (MRI) and magnetic resonance spectroscopy imaging (MRSI) before radiation therapy (RT) is valuable for RT target definition, and to evaluate the feasibility of replacing the current definition of uniform margins by custom-shaped margins based on the information from MRI and MRSI.

METHODS AND MATERIALS

A total of 23 glioblastoma multiforme (GBM) patients underwent MRI and MRSI within 4 weeks after surgery but before the initiation of RT and at 2-month follow-up intervals thereafter. The MRSI data were quantified on the basis of a Choline-to-NAA Index (CNI) as a measure of spectroscopic abnormality. A combined anatomic and metabolic region of interest (MRI/S) consisting of T2-weighted hyperintensity, contrast enhancement (CE), resection cavity, and CNI2 (CNI >or= 2) based on the pre-RT imaging was compared to the extent of CNI2 and the RT dose distribution. The spatial relationship of the pre-RT MRI/S and the RT dose volume was compared with the extent of CE at each follow-up.

RESULTS

Nine patients showed new or increased CE during follow-up, and 14 patients were either stable or had decreased CE. New or increased areas of CE occurred within CNI2 that was covered by 60 Gy in 6 patients and within the CNI2 that was not entirely covered by 60 Gy in 3 patients. New or increased CE resided within the pre-RT MRI/S lesion in 89% (8/9) of the patients with new or increased CE.

CONCLUSION

These data indicate that the definition of RT target volumes according to the combined morphologic and metabolic abnormality may be sufficient for RT targeting.

Longitudinal multivoxel MR spectroscopy study of pediatric diffuse brainstem gliomas treated with radiotherapy

BACKGROUND AND PURPOSE

After radiotherapy (RT), children with diffuse intrinsic pontine gliomas (DIPG) are followed with sequential magnetic resonance imaging (MRI). However, MRI changes do not necessarily reflect tumor progression, and therefore additional noninvasive tools are needed to improve the definition of progression vs. treatment-related changes. In this study, we determined the feasibility and accuracy of multivoxel proton magnetic resonance spectroscopic imaging (1H-MRSI) for monitoring pediatric patients with DIPG.

METHODS AND PATIENTS

Twenty-four serial examinations of MRI/MRSI (7 2D-MRSI and 17 3D-MRSI) were performed on 8 patients with DIPG who received local RT. A total of 1635 voxels were categorized as "normal" or "abnormal" based on corresponding imaging findings on contrast-enhanced T1- and T2-weighted MRI. The choline to N-acetyl-aspartate ratio (Cho:NAA) and choline to creatine ratios (Cho:Cr) within each category of MRI abnormality were compared to their counterpart in normal surrounding tissues. The changes in these ratios corresponding to each type of abnormality were evaluated before RT, at response, and at recurrence, as determined by the clinical status of the patients. The presence or absence of lactate and lipid peaks was noted for each voxel. MRI/MRSI was performed on posterior fossa and supratentorial tissue of 3 volunteer pediatric patients.

RESULTS

The Cho:NAA and Cho:Cr values within the imaging abnormalities (3.8 +/- 0.93 and 3.55 +/- 1.37, respectively) were significantly higher than the mean values in normal-appearing regions (0.93 +/- 0.2 and 1.13 +/- 0.38, respectively) (p < 0.005). Cho:NAA values decreased from studies at diagnosis to the time of response to RT (3.12 +/- 0.5 and 2.08 +/- 0.73, respectively), followed by an increase at the time of relapse (from 1.83 +/- 0.92 to 4.29 +/- 1.08). Loss of lactate and lipid peaks correlated with response, and their presence and stability with relapse. In 3 patients, increased spectral abnormalities preceded the radiological and clinical deterioration by 2-5 months.

CONCLUSION

Multivoxel MRSI is a feasible and reproducible noninvasive tool for assessing pediatric DIPG. Longitudinal multivoxel MRSI measurements have potential value in assessing response to radiation or other therapies, because they offer more coverage than single-voxel techniques and provide reliable spectral data.

Proton magnetic resonance spectroscopy imaging in the evaluation of patients undergoing gamma knife surgery for Grade IV glioma

Object. The purpose of this study was to assess the differences in spatial extent and metabolic activity in a comparison of a radiosurgical target defined by conventional strategies that utilize the enhancing lesion and a metabolic lesion defined by proton magnetic resonance spectroscopy (MRS) imaging. The authors evaluated whether these differences manifest themselves in the clinical outcome of patients and assessed the value of incorporating 1H-MRS imaging—derived spatial information into the treatment planning process for gamma knife surgery (GKS).

Methods. Twenty-six patients harboring Grade IV gliomas who had previously been treated with external-beam radiation therapy were evaluated by comparing the radiosurgically treated lesion volume with the volume of metabolically active tumor defined on 1H-MRS imaging. The cohort was evenly divided into two groups based on the percentage of overlap between the radiosurgical target and the metabolic lesion volumes. Patients with a percentage of overlap greater than 50% with respect to the metabolic lesion volume were classified as low risk and those with an overlap less than 50% were classified as high risk.

Kaplan—Meier estimators were calculated using time to progression and survival as dependent variables. The metabolite levels within the metabolic lesion were significantly greater than those within the radiosurgical target (p ≤ 0.001). The median survival was 15.7 months for patients in the low-risk group and 10.4 months for those in the highrisk group. This difference was statistically significant (p < 0.01).

Conclusions. Analysis of the results of this study indicates that patients undergoing GKS may benefit from the inclusion of 1H-MRS imaging in the treatment planning process.