OS05.2.A MGMT promoter status in IDH1/2 mutant anaplastic astrocytoma patients assessed by DNA methylation profiling and qMS-PCR: a report from the EORTC Brain Tumor Group

BACKGROUND

Temozolomide (TMZ) efficacy in high-grade glioma is related to O 6-methylguanine DNA methyltransferase promoter (MGMTp) methylation. We compared the prognostic and predictive effect of MGMTp between DNA methylation profiling (the MGMT-STP27 model) and quantitative methylation specific polymerase chain reaction (qMS-PCR) in isocitrate dehydrogenase 1 and 2 (IDH1/2) mutant (mt) anaplastic astrocytoma patients.

MATERIAL AND METHODS

The 2x2 factorial design phase III CATNON trial randomized 751 adult patients with newly diagnosed 1p/19q non-codeleted anaplastic glioma to 59.4 Gy radiotherapy (RT), RT with concurrent TMZ, RT with 12 cycles of adjuvant TMZ, or RT with concurrent and adjuvant TMZ. MGMTp methylation status was assessed with the MGMT-STP27 model using 850k EPIC data, and qMS-PCR. IDH1/2 mutation status was determined with a next-generation sequencing panel. Overall survival (OS) was measured from date of randomization.

RESULTS

We identified 444 IDH1/2mt anaplastic astrocytoma patients of which MGMT-STP27 data was available for 440 patients (99.1%), qMS-PCR data for 361 patients (81.3%), and both for 357 patients (80.4%). MGMTp was methylated in 365 patients (83.0%) for the MGMT-STP27 model, and 168 patients (46.5%) for qMS-PCR. The agreement between the MGMT-STP27 model and qMS-PCR is 59.9% with a Cohen’s Kappa score of 0.229. At database lock, 289 patients with MGMT-STP27 data were still alive and 236 patients with qMS-PCR data. The median OS of MGMTp methylated glioma patients was 9.1 yrs [95 % confidence interval (CI) 7.5-not reached] for the MGMT-STP27 model, and not reached [95 % CI 9.1-not reached] for the qMS-PCR data. For MGMTp unmethylated glioma patients, the median OS was 6.9 yrs [95% CI 6.2-not reached] for the MGMT-STP27 model, and 6.8 yrs [95% CI 6.2–9.7] for the qMS-PCR data. The hazard ratio (HR) for OS based on MGMTp methylation was 0.88 [95% CI 0.58–1.31] for the MGMT-STP27 data, and 0.72 [95% CI 0.50–1.03]) for the qMS-PCR data. The HR for OS after RT with any TMZ vs RT alone for the MGMT-STP27 model was 0.53 [95% CI 0.37–0.78] for MGMTp methylated, and 0.54 [95% CI 0.25–1.18] for MGMTp unmethylated glioma patients; and for the MS-PCR data was 0.34 [95% CI 0.19–0.61] for MGMTp methylated, and 0.53 [95% CI 0.33–0.85] for MGMTp unmethylated glioma patients.

CONCLUSION

MGMTp methylation, regardless of assay, was neither prognostic nor predictive for outcome to temozolomide in IDH1/2mt anaplastic astrocytoma patients.

Prognostic significance of genome-wide DNA methylation profiles within the randomised, phase 3, EORTC CATNON trial on non-1p/19q deleted anaplastic glioma

Background

Survival in patients with IDH1/2-mutant (mt) anaplastic astrocytomas is highly variable. We have used the prospective phase 3 CATNON trial to identify molecular factors related to outcome in IDH1/2mt anaplastic astrocytoma patients.

Methods

The CATNON trial randomized 751 adult patients with newly diagnosed 1p/19q non-codeleted anaplastic glioma to 59.4 Gy radiotherapy +/− concurrent and/or adjuvant temozolomide. The presence of necrosis and/or microvascular proliferation was scored at central pathology review. Infinium MethylationEPIC BeadChip arrays were used for genome-wide DNA methylation analysis and the determination of copy number variations (CNV). Two DNA methylation-based tumor classifiers were used for risk stratification. Next-generation sequencing (NGS) was performed using 1 of the 2 glioma-tailored NGS panels. The primary endpoint was overall survival measured from the date of randomization.

Results

Full analysis (genome-wide DNA methylation and NGS) was successfully performed on 654 tumors. Of these, 432 tumors were IDH1/2mt anaplastic astrocytomas. Both epigenetic classifiers identified poor prognosis patients that partially overlapped. A predictive prognostic Cox proportional hazard model identified that independent prognostic factors for IDH1/2mt anaplastic astrocytoma patients included; age, mini-mental state examination score, treatment with concurrent and/or adjuvant temozolomide, the epigenetic classifiers, PDGFRA amplification, CDKN2A/B homozygous deletion, PI3K mutations, and total CNV load. Independent recursive partitioning analysis highlights the importance of these factors for patient prognostication.

Conclusion

Both clinical and molecular factors identify IDH1/2mt anaplastic astrocytoma patients with worse outcome. These results will further refine the current WHO criteria for glioma classification.

Durvalumab with or without tremelimumab in patients with recurrent or metastatic head and neck squamous cell carcinoma: EAGLE, a randomized, open-label phase III study

BACKGROUND

Targeting the programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) axis has demonstrated clinical benefit in recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC). Combining immunotherapies targeting PD-L1 and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) has shown evidence of additive activity in several tumor types. This phase III study evaluated the efficacy of durvalumab (an anti-PD-L1 monoclonal antibody) or durvalumab plus tremelimumab (an anti-CTLA-4 monoclonal antibody) versus standard of care (SoC) in R/M HNSCC patients.

PATIENTS AND METHODS

Patients were randomly assigned to receive 1 : 1 : 1 durvalumab (10 mg/kg every 2 weeks [q2w]), durvalumab plus tremelimumab (durvalumab 20 mg/kg q4w plus tremelimumab 1 mg/kg q4w × 4, then durvalumab 10 mg/kg q2w), or SoC (cetuximab, a taxane, methotrexate, or a fluoropyrimidine). The primary end points were overall survival (OS) for durvalumab versus SoC, and OS for durvalumab plus tremelimumab versus SoC. Secondary end points included progression-free survival (PFS), objective response rate, and duration of response.

RESULTS

Patients were randomly assigned to receive durvalumab (n = 240), durvalumab plus tremelimumab (n = 247), or SoC (n = 249). No statistically significant improvements in OS were observed for durvalumab versus SoC [hazard ratio (HR): 0.88; 95% confidence interval (CI): 0.72-1.08; P = 0.20] or durvalumab plus tremelimumab versus SoC (HR: 1.04; 95% CI: 0.85-1.26; P = 0.76). The 12-month survival rates (95% CI) were 37.0% (30.9-43.1), 30.4% (24.7-36.3), and 30.5% (24.7-36.4) for durvalumab, durvalumab plus tremelimumab, and SoC, respectively. Treatment-related adverse events (trAEs) were consistent with previous reports. The most common trAEs (any grade) were hypothyroidism for durvalumab and durvalumab plus tremelimumab (11.4% and 12.2%, respectively), and anemia (17.5%) for SoC. Grade ≥3 trAE rates were 10.1%, 16.3%, and 24.2% for durvalumab, durvalumab plus tremelimumab, and SoC, respectively.

CONCLUSION

There were no statistically significant differences in OS for durvalumab or durvalumab plus tremelimumab versus SoC. However, higher survival rates at 12 to 24 months and response rates demonstrate clinical activity for durvalumab.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02369874.

PL3.3 Second interim and first molecular analysis of the EORTC randomized phase III intergroup CATNON trial on concurrent and adjuvant temozolomide in anaplastic glioma without 1p/19q codeletion

BACKGROUND

The 1st interim analysis of the CATNON trial showed benefit from adjuvant (adj) temozolomide (TMZ) on overall survival (OS) but remained inconclusive about concurrent (conc) TMZ. A 2nd interim analysis was planned after 356 events.

MATERIAL AND METHODS

The 2x2 factorial design phase III CATNON trial randomized 751 adult patients with newly diagnosed non-codeleted anaplastic glioma to either 59.4 Gy radiotherapy (RT) alone; the same RT with concTMZ; the same RT and 12 cycles of adjTMZ or the same RT with both concTMZ and adjTMZ (doi: 10.1016/S0140-6736(17)31442-3). MGMT promoter methylation (MGMTmeth) status was re-assessed with the Infinium Methylation EPIC Beadchip using the MGMT_STP27 model. Isocitrate dehydrogenase 1 and 2 (IDH) mutation (mt) status was assessed with glioma targeted Agilent SureSelect baits sequence using an Illumina HiSeq2500 Rapid PE100.

RESULTS

With a median follow-up of 56 months and 356 events, the hazard ratio (HR) for OS adjusted for stratification factors after concTMZ was 0.968 (99.1% CI 0.73, 1.28). 5-year OS was 50.2% with and 52.7% without concTMZ (95% CI [44.4, 55.7] and [46.9, 58.1]). An IDHmt was found in 335 of 480 assessed cases (70%). Median OS was 19 mo (95% CI 16.3, 22.3) in IDHwt tumors and 116 mo (95% CI 82.0, 116.6) in IDHmt tumors. The interaction test based on IDH status was significant (p=0.016) in the univariate HR analysis for OS after concTMZ (IDHwt, n=145, events=120, HR = 1.27, 95% CI 0.89, 1.82, p=0.19; IDHmt, n=335, events=92, HR= 0.67, 95% CI 0.44, 1.03, p=0.06). IDHmt was predictive of benefit from adjTMZ (IDHmt HR: 0.41, 95% CI 0.27, 0.64; IDHwt: HR 1.05, 95% CI 0.73, 1.52; interaction test p = 0.001). In IDHmt patients that received adjTMZ, the HR for OS after concTMZ was 0.71 (95% CI 0.35, 1.42, p=0.32). MGMTmeth was found in 288 of 410 assessed cases (70%), interaction test for concTMZ (p = 0.092) and adjTMZ (p = 0.166) did not reach statistical significance.

CONCLUSION

In the entire study cohort, concTMZ did not increase OS. However, in IDHmt tumors a trend towards benefit of concTMZ is present. AdjTMZ increased OS in IDHmt but not in IDHwt tumors. Further analyses and follow-up will allow full assessment of efficacy in the molecular subgroups.

Biomarkers predict enhanced clinical outcomes with afatinib versus methotrexate in patients with second-line recurrent and/or metastatic head and neck cancer

Background

In the phase III LUX-Head & Neck 1 (LUX-H&N1) trial, second-line afatinib significantly improved progression-free survival (PFS) versus methotrexate in patients with recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC). Here, we evaluated association of prespecified biomarkers with efficacy outcomes in LUX-H&N1.

Patients and methods

Randomized patients with R/M HNSCC and progression following ≥2 cycles of platinum therapy received afatinib (40 mg/day) or methotrexate (40 mg/m2/week). Tumor/serum samples were collected at study entry for patients who volunteered for inclusion in biomarker analyses. Tumor biomarkers, including p16 (prespecified subgroup; all tumor subsites), EGFR, HER2, HER3, c-MET and PTEN, were assessed using tissue microarray cores and slides; serum protein was evaluated using the VeriStrat® test. Biomarkers were correlated with efficacy outcomes.

Results

Of 483 randomized patients, 326 (67%) were included in the biomarker analyses; baseline characteristics were consistent with the overall study population. Median PFS favored afatinib over methotrexate in patients with p16-negative [2.7 versus 1.6 months; HR 0.70 (95% CI 0.50-0.97)], EGFR-amplified [2.8 versus 1.5 months; HR 0.53 (0.33-0.85)], HER3-low [2.8 versus 1.8 months; HR 0.57 (0.37-0.88)], and PTEN-high [1.6 versus 1.4 months; HR 0.55 (0.29-1.05)] tumors. Afatinib also improved PFS in combined subsets of patients with p16-negative and EGFR-amplified tumors [2.7 versus 1.5 months; HR 0.47 (0.28-0.80)], and patients with p16-negative tumors who were EGFR therapy-naïve [4.0 versus 2.4 months; HR 0.55 (0.31-0.98)]. PFS was improved in afatinib-treated patients who were VeriStrat 'Good' versus 'Poor' [2.7 versus 1.5 months; HR 0.71 (0.49-0.94)], but no treatment interaction was observed. Afatinib improved tumor response versus methotrexate in all subsets analyzed except for those with p16-positive disease (n = 35).

Conclusions

Subgroups of HNSCC patients who may achieve increased benefit from afatinib were identified based on prespecified tumor biomarkers (p16-negative, EGFR-amplified, HER3-low, PTEN-high). Future studies are warranted to validate these findings.

Clinical trial registration

NCT01345682.

TPF plus cetuximab induction chemotherapy followed by biochemoradiation with weekly cetuximab plus weekly cisplatin or carboplatin: a randomized phase II EORTC trial

Background

Our aim was to test the safety of cetuximab added to chemoradiation with either cisplatin or carboplatin after prior induction chemotherapy.

Methods

Patients with stage III/IV unresectable, squamous cell carcinoma of the head and neck received up to four cycles of TPF-E (cisplatin and docetaxel 75 mg/m2 on day 1 followed by 5-FU 750 mg/m2/day as a continuous infusion on days 1-5 plus cetuximab at a loading dose of 400 mg/m2 followed by a weekly dose of 250 mg/m2), with prophylactic antibiotics but no growth factors. Patients not progressing after four cycles of TPF-E were randomly assigned to radiotherapy (70 Gy over 7 weeks in 2 Gy fractions) and weekly cetuximab with either weekly cisplatin 40 mg/m2 or carboplatin, AUC of 1.5 mg/ml/min. Primary endpoint was feasibility.

Results

Forty-seven patients were recruited. One patient did not start TPF (hypersensitivity reaction during the cetuximab loading dose). Induction TPF-E was discontinued in 12 patients due to toxicity (6 patients), medical decision (2), death (1), patient refusal (1), protocol violation (1), co-morbidity (1). Three further patients were not randomized [progressive disease (1), protocol violation (1), toxicity and co-morbidity (1)]. Of particular interest are three patients who suffered from bowel perforation, one patient who died as results of pneumonia and septic shock, and a second patient who was found dead at home 12 days after starting TPF-E (cause of death unknown). Weekly cisplatin and carboplatin was stopped early in seven and four patients, respectively. Radiotherapy was stopped in two patients with cisplatin and interrupted in one patient with cisplatin and four patients with carboplatin.

Conclusions

The addition of cetuximab to full dose TPF induction chemotherapy led to unacceptable complications and premature closing of the study. Only 34 out of 46 patients completed four cycles of TPF-E and only 30 started biochemoradiation.

Afatinib versus methotrexate in older patients with second-line recurrent and/or metastatic head and neck squamous cell carcinoma: subgroup analysis of the LUX-Head & Neck 1 trial

BACKGROUND

In the phase III LUX-Head & Neck 1 (LHN1) trial, afatinib significantly improved progression-free survival (PFS) versus methotrexate in recurrent and/or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) patients progressing on/after platinum-based therapy. This report evaluates afatinib efficacy and safety in prespecified subgroups of patients aged ≥65 and <65 years.

PATIENTS AND METHODS

Patients were randomized (2:1) to 40 mg/day oral afatinib or 40 mg/m(2)/week intravenous methotrexate. PFS was the primary end point; overall survival (OS) was the key secondary end point. Other end points included: objective response rate (ORR), patient-reported outcomes, tumor shrinkage, and safety. Disease control rate (DCR) was also assessed.

RESULTS

Of 483 randomized patients, 27% (83 afatinib; 45 methotrexate) were aged ≥65 years (older) and 73% (239 afatinib; 116 methotrexate) <65 years (younger) at study entry. Similar PFS benefit with afatinib versus methotrexate was observed in older {median 2.8 versus 2.3 months, hazard ratio (HR) = 0.68 [95% confidence interval (CI) 0.45-1.03], P = 0.061} and younger patients [2.6 versus 1.6 months, HR = 0.79 (0.62-1.01), P = 0.052]. In older and younger patients, the median OS with afatinib versus methotrexate was 7.3 versus 6.4 months [HR = 0.84 (0.54-1.31)] and 6.7 versus 6.2 months [HR = 0.98 (0.76-1.28)]. ORRs with afatinib versus methotrexate were 10.8% versus 6.7% and 10.0% versus 5.2%; DCRs were 53.0% versus 37.8% and 47.7% versus 38.8% in older and younger patients, respectively. In both subgroups, the most frequent treatment-related adverse events were rash/acne (73%-77%) and diarrhea (70%-80%) with afatinib, and stomatitis (43%) and fatigue (31%-34%) with methotrexate. Fewer treatment-related discontinuations were observed with afatinib (each subgroup 7% versus 16%). A trend toward improved time to deterioration of global health status, pain, and swallowing with afatinib was observed in both subgroups.

CONCLUSIONS

Advancing age (≥65 years) did not adversely affect clinical outcomes or safety with afatinib versus methotrexate in second-line R/M HNSCC patients.

CLINICAL TRIAL REGISTRATION

NCT01345682 (ClinicalTrials.gov).

Comparison of diagnostic accuracy of (111)In-pentetreotide SPECT and (68)Ga-DOTATOC PET/CT: A lesion-by-lesion analysis in patients with metastatic neuroendocrine tumours

OBJECTIVES

To compare the diagnostic accuracy of (111)In-pentetreotide-scintigraphy with (68)Ga-DOTATOC-positron emission tomography (PET)/computed tomography (CT) in patients with metastatic-neuroendocrine tumour (NET) scheduled for peptide receptor radionuclide therapy (PRRT). Incremental lesions (ILs) were defined as lesions observed on only one modality.

METHODS

Fifty-three metastatic-NET-patients underwent (111)In-pentetreotide-scintigraphy (24 h post-injection; planar+single-photon emission CT (SPECT) abdomen) and whole-body (68)Ga-DOTATOC-PET/CT. SPECT and PET were compared in a lesion-by-lesion and organ-by-organ analysis, determining the total lesions and ILs for both modalities.

RESULTS

Significantly more lesions were detected on (68)Ga-DOTATOC-PET/CT versus (111)In-pentetreotide-scintigraphy. More specifically, we observed 1,098 lesions on PET/CT (range: 1-105; median: 15) versus 660 on SPECT (range: 0-73, median: 9) (p<0.0001), with 439 PET-ILs (42/53 patients) and one SPECT-IL (1/53 patients). The sensitivity for PET/CT was 99.9 % (95 % CI, 99.3-100.0), for SPECT 60.0 % (95 % CI, 48.5-70.2). The organ-by-organ analysis showed that the PET-ILs were most frequently visualized in liver and skeleton.

CONCLUSION

Ga-DOTATOC-PET/CT is superior for the detection of NET-metastases compared to (111)In-pentetreotide SPECT.

KEY POINTS

Somatostatin receptor PET is superior to SPECT in detecting NET metastases. PET is the scintigraphic method for accurate depiction of NET tumour burden. The sensitivity of PET is twofold higher than the sensitivity of SPECT.

A randomized, phase II study of afatinib versus cetuximab in metastatic or recurrent squamous cell carcinoma of the head and neck

BACKGROUND

Afatinib is an oral, irreversible ErbB family blocker that has shown activity in epidermal growth factor receptor (EGFR)-mutated lung cancer. We hypothesized that the agent would have greater antitumor activity compared with cetuximab in recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) patients, whose disease has progressed after platinum-containing therapy.

PATIENTS AND METHODS

An open-label, randomized, phase II trial was conducted in 43 centers; 124 patients were randomized (1 : 1) to either afatinib (50 mg/day) or cetuximab (250 mg/m(2)/week) until disease progression or intolerable adverse events (AEs) (stage I), with optional crossover (stage II). The primary end point was tumor shrinkage before crossover assessed by investigator (IR) and independent central review (ICR).

RESULTS

A total of 121 patients were treated (61 afatinib, 60 cetuximab) and 68 crossed over to stage II (32 and 36 respectively). In stage I, mean tumor shrinkage by IR/ICR was 10.4%/16.6% with afatinib and 5.4%/10.1% with cetuximab (P = 0.46/0.30). Objective response rate was 16.1%/8.1% with afatinib and 6.5%/9.7% with cetuximab (IR/ICR). Comparable disease control rates were observed with afatinib (50%) and cetuximab (56.5%) by IR; similar results were seen by ICR. Most common grade ≥3 drug-related AEs (DRAEs) were rash/acne (18% versus 8.3%), diarrhea (14.8% versus 0%), and stomatitis/mucositis (11.5% versus 0%) with afatinib and cetuximab, respectively. Patients with DRAEs leading to treatment discontinuation were 23% with afatinib and 5% with cetuximab. In stage II, disease control rate (IR/ICR) was 38.9%/33.3% with afatinib and 18.8%/18.8% with cetuximab.

CONCLUSION

Afatinib showed antitumor activity comparable to cetuximab in R/M HNSCC in this exploratory phase II trial, although more patients on afatinib discontinued treatment due to AEs. Sequential EGFR/ErbB treatment with afatinib and cetuximab provided sustained clinical benefit in patients after crossover, suggesting a lack of cross-resistance.

Cisplatin, 5-fluorouracil, and cetuximab (PFE) with or without cilengitide in recurrent/metastatic squamous cell carcinoma of the head and neck: results of the randomized phase I/II ADVANTAGE trial (phase II part)

BACKGROUND

Recurrent and/or metastatic squamous cell carcinoma of the head and neck (R/M-SCCHN) overexpresses αvβ5 integrin. Cilengitide selectively inhibits αvβ3 and αvβ5 integrins and is investigated as a treatment strategy.

PATIENTS AND METHODS

The phase I/II study ADVANTAGE evaluated cilengitide combined with cisplatin, 5-fluorouracil, and cetuximab (PFE) in R/M-SCCHN. The phase II part reported here was an open-label, randomized, controlled trial investigating progression-free survival (PFS). Patients received up to six cycles of PFE alone or combined with cilengitide 2000 mg once (CIL1W) or twice (CIL2W) weekly. Thereafter, patients received maintenance therapy (cilengitide arms: cilengitide plus cetuximab; PFE-alone arm: cetuximab only) until disease progression or unacceptable toxicity.

RESULTS

One hundred and eighty-two patients were treated. Median PFS per investigator read was similar for CIL1W + PFE, CIL2W + PFE, and PFE alone (6.4, 5.6, and 5.7 months, respectively). Accordingly, median overall survival and objective response rates were not improved with cilengitide (12.4 months/47%, 10.6 months/27%, and 11.6 months/36%, respectively). No clinically meaningful safety differences were observed between groups. None of the tested biomarkers (expression of integrins, CD31, Ki-67, vascular endothelial growth factor receptor 2, vascular endothelial-cadherin, type IV collagen, epidermal growth factor receptor, or p16 for human papillomavirus) were predictive of outcome.

CONCLUSION

Neither of the cilengitide-containing regimens demonstrated a PFS benefit over PFE alone in R/M-SCCHN patients.

Defining pseudoprogression in glioblastoma multiforme

BACKGROUND AND PURPOSE

Pseudoprogression is a frequent phenomenon observed since the introduction of postoperative therapy with radiotherapy and temozolomide (RT/TMZ) in glioblastoma multiforme (GBM) patients. However, the criteria defining pseudoprogression, its incidence, the time of occurrence and its impact on therapy and outcome remain poorly defined.

METHODS

The objective of this study is to compare two sets of criteria (liberal and stringent), defining pseudoprogression, in a cohort of patients treated before and after the introduction of RT/TMZ in the standard postoperative treatment. This retrospective review includes 136 unselected and consecutively treated patients with pathologically diagnosed GBM.

RESULTS

Pseudoprogression was observed in 10 (12%) cases applying the stringent criteria, and in 18 (23%) patients when using the liberal criteria, in the cohort treated with RT/TMZ. Pseudoprogression was observed in only one patient treated with RT alone. The median time to pseudoprogression was 4 weeks after the end of RT. Patients with pseudoprogression had a median survival time of 28 months, compared with 12 months for patients without pseudoprogression.

CONCLUSIONS

The incidence of pseudoprogression after RT/TMZ strongly depends on the applied criteria. However, regardless of the stringency of the criteria, the impact on survival remains the same.

Role of GRB2-associated binder 1 in epidermal growth factor receptor-induced signaling in head and neck squamous cell carcinoma

The epidermal growth factor receptor (EGFR) plays an important role in the pathogenesis of head and neck squamous cell carcinoma (HNSCC). Despite the high expression of EGFR in HNSCC, EGFR inhibitors have only limited success as monotherapy. The Grb2-associated binder (GAB) family of adaptor proteins acts as docking/scaffolding molecules downstream of tyrosine kinase receptors. We hypothesized that GAB1 may amplify EGFR-induced signaling in HNSCCs and therefore could play a role in the reduced sensitivity of HNSCC to EGFR inhibitors. We used representative human HNSCC cell lines overexpressing wild type EGFR, and expressing GAB1 but not GAB2. We demonstrated that baseline Akt and MAPK signaling were reduced in HNSCC cells in which GAB1 expression was reduced. Furthermore, the maximal EGF-induced activation of the Akt and MAPK pathway was reduced and delayed, and the duration of the EGF-induced activation of these pathways was reduced in cells with GAB1 knock-down. In agreement with this, HNSCC cells in which GAB1 levels were reduced showed an increased sensitivity to the EGFR inhibitor gefitinib. Our work demonstrates that GAB1 plays an important role as part of the mechanism of by which EGFR induces induced activation of the MAPK and AKT pathway. Our results identify GAB1 as an amplifier of the EGFR-initiated signaling, which may also interfere with EGFR degradation. These findings support the emerging notion that reducing GAB1 function may sensitize HNSCC to EGFR inhibitors, hence representing a new therapeutic target HNSCC treatment in combination with EGFR targeting agents.

An open-label, randomized, phase III trial of zalutumumab, a human monoclonal EGF receptor (EGFr) antibody, versus best supportive care, in patients with noncurable squamous cell carcinoma (SCCHN) of the head and neck who have failed standard platinum-based chemotherapy (ZALUTE)

LBA5506

Background: Zalutumumab is a novel, fully human IgG1 mAb targeting the EGFr that has shown encouraging activity in SCCHN.

Methods: Patients with noncurable SCCHN with an ECOG PS of 0-2 and centrally documented radiographic progressive disease (PD) within 6 months after platinum-therapy were randomized between zalutumumab monotherapy and best supportive care (BSC) in a 2:1 ratio. Stratification parameter was ECOG PS. Methotrexate (MTX) was allowed in the BSC arm only. Individual dose-titration of zalutumumab was applied (max. exposure 16 mg/kg). The primary endpoint was overall survival (OS), with progression free survival (PFS) as the only secondary endpoint to be compared between groups, using log-rank test. 231 deaths were required to statistically differentiate OS between groups with 80% power.

Results: 286 patients (34F, 252M) were randomized. The median age was 57 years (range 18-78), 65% had distant metastasis and 17% were ECOG PS 2, all similar between groups. 78% of patients in BSC arm received MTX. Although a median OS of 6.7 months was observed in the zalutumumab group compared to 5.2 in the BSC group, this was not statistically significant (p=0.065). A clear improvement in PFS (P=0.001) was demonstrated. Zalutumumab showed a safety profile as expected within this drug class.

Conclusions: This is the first controlled study to demonstrate that an EGFr-targeted antibody given as monotherapy induces a clinically meaningful improvement in PFS in patients with SSCHN who have failed platinum-based chemotherapy.

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