iRECIST and atypical patterns of response to immuno-oncology drugs.

With the advent of immunotherapy as one of the keystones of the treatment of our patients with cancer, a number of atypical patterns of response to these agents has been identified. These include pseudoprogression, where the tumor initially shows objective growth before decreasing in size, and hyperprogression, hypothesized to be a drug-induced acceleration of the tumor burden. Despite it being >10 years since the first immune-oncology drug was approved, neither the biology behind these paradoxical responses has been well understood, nor their incidence, identification criteria, predictive biomarkers, or clinical impact have been fully described. Immune-based Response Evaluation Criteria in Solid Tumors (iRECIST) guidelines have been published as a revision to the RECIST V.1.1 criteria for use in trials of immunotherapeutics, and the iRECIST subcommittee (of the RECIST Working Group) is working on elucidating these aspects, with data sharing a current major challenge to move forward with this unmet need in immuno-oncology.

EGFR-mutated lung adenocarcinomas from patients who progressed on EGFR-inhibitors show high engraftment rates in xenograft models.

OBJECTIVE: Patient-derived xenografts (PDX) are useful preclinical models to study cancer biology and mechanisms of drug response/resistance, particularly in molecularly targetable tumors. However, PDX engraftment may not be stochastic. We investigated clinical, histological and molecular features associated with PDX engraftment in a large cohort of EGFR-mutated lung adenocarcinoma (LUAD). MATERIAL AND METHODS: Samples were collected by different methods from patients at various disease stages and phases of treatment. PDX engraftment was defined as an ability to passage tumors twice in NOD-SCID mice. Uni- and multivariate logistic regression evaluated factors associated with engraftment. RESULTS: Among 138 EGFR-mutated LUAD implanted into NOD-SCID mice, the overall engraftment rate was only 10% (14/138). However, engraftment was significantly higher in specimens from surgical resections or core-needle biopsies collected from metastatic sites (5/5; 100%) or from patients who had progressed on EGFR-inhibitors (7/10; 70%). Engrafted tumors usually showed poor histological differentiation, a solid morphologic pattern, and presence of either EGFR T790 M and/or TP53 mutations. CONCLUSIONS: Population level analyses of mutant EGFR-PDX show that these models might not fully recapitulate the inter-patient heterogeneity of EGFR-LUAD. However, mutant EGFR-PDXs may be useful to address key clinical questions, notably development of resistance to EGFR-inhibitors and disease progression to distant metastases.

Prognostic and predictive effects of TP53 co-mutation in patients with EGFR-mutated non-small cell lung cancer (NSCLC).

INTRODUCTION: TP53 mutations are common in non-small cell lung cancer (NSCLC) and have been reported as prognostic of poor outcome. The impact of TP53 co-mutations in epidermal growth factor receptor (EGFR)-mutated NSCLC is unclear. MATERIALS AND METHODS: Tissue from 105 patients with EGFR-mutated NSCLC at Princess Margaret Cancer Centre was analyzed by next-generation or Sanger sequencing to determine TP53 mutational status. Associations between TP53 status and baseline patient and tumor characteristics, treatments and outcomes (relapse-free survival [RFS] after surgical resection, overall survival [OS], overall response rate [ORR] and progression-free survival [PFS] on EGFR tyrosine kinase inhibitors [TKIs]), were investigated. RESULTS: Dual TP53/EGFR mutations were found in 43/105 patients (41%). Among 76 patients who underwent surgical resection, neither RFS (HR 0.99, CI 0.56-1.75, p=0.96) nor OS (HR 1.39, CI 0.70-2.77; p=0.35) was associated with TP53 status. Sixty patients (24 TP53 MUT; 36 TP53 WT) received first-generation EGFR TKIs for advanced disease. ORR was not significantly different (TP53 MUT 54%, WT 66%, p=0.42). There was a non-significant trend towards shorter PFS on EGFR TKIs with TP53 mutation (HR 1.74, CI 0.98-3.10, p=0.06). When limited to TP53 missense mutations (n=17), PFS was significantly shorter (HR 1.91, CI 1.01-3.60, p=0.04). Among 11 evaluable patients treated with T790M inhibitors, ORR was not significantly different (TP53 MUT 3/3 [100%], WT 7/8 [88%]). CONCLUSIONS: Patients with dual TP53/EGFR mutations, especially missense mutations, had marginally lower response rates and shorter PFS when treated with EGFR TKI therapy. Larger datasets are required to validate these observations.

Dacomitinib compared with placebo in pretreated patients with advanced or metastatic non-small-cell lung cancer (NCIC CTG BR.26): a double-blind, randomised, phase 3 trial.

BACKGROUND: Dacomitinib is an irreversible pan-HER tyrosine-kinase inhibitor with preclinical and clinical evidence of activity in non-small-cell lung cancer. We designed BR.26 to assess whether dacomitinib improved overall survival in heavily pretreated patients with this disease. METHODS: In this double-blind, randomised, placebo-controlled, phase 3 trial, we enrolled adults (aged ≥18 years) with advanced or metastatic non-small-cell lung cancer from 75 centres in 12 countries. Eligible patients had received up to three previous lines of chemotherapy and either gefitinib or erlotinib, and had assessable disease (RECIST 1.1) and tumour tissue samples for translational studies. Patients were stratified according to centre, performance status, tobacco use, best response to previous EGFR tyrosine-kinase inhibitor, weight loss within the previous 3 months, and ethnicity, and were then randomly allocated 2:1 to oral dacomitinib 45 mg once-daily or matched placebo centrally via a web-based system. Treatment continued until disease progression or unacceptable toxicity. The primary outcome was overall survival in the intention-to-treat population; secondary outcomes included overall survival in predefined molecular subgroups, progression-free survival, the proportion of patients who achieved an objective response, safety, and quality of life. This study is completed, although follow-up is ongoing for patients on treatment. This study is registered with ClinicalTrials.gov, number NCT01000025. FINDINGS: Between Dec 23, 2009, and June 11, 2013, we randomly assigned 480 patients to dacomitinib and 240 patients to placebo. At the final analysis (January, 2014), median follow-up was 23·4 months (IQR 15·6-29·6) for patients in the dacomitinib group and 24·4 months (11·5-38·9) for those in the placebo group. Dacomitinib did not improve overall survival compared with placebo (median 6·83 months [95% CI 6·08-7·49] for dacomitinib vs 6·31 months [5·32-7·52] for placebo; hazard ratio [HR] 1·00 [95% CI 0·83-1·21]; p=0·506). However, patients in the dacomitinib group had longer progression-free survival than those in the placebo group (median 2·66 months [1·91-3·32] vs 1·38 months [0·99-1·74], respectively; HR 0·66 [95% CI 0·55-0·79]; p<0·0001), and a significantly greater proportion of patients in the dacomitinb group achieved an objective response than in the placebo group (34 [7%] of 480 patients vs three [1%] of 240 patients, respectively; p=0·001). Compared with placebo, the effect of dacomitinib on overall survival seemed similar in patients with EGFR-mutation-positive tumours (HR 0·98, 95% CI 0·67-1·44) and EGFR wild-type tumours (0·93, 0·71-1·21; pinteraction=0·69). However, we noted qualitative differences in the effect of dacomitinib on overall survival for patients with KRAS-mutation-positive tumours (2·10, 1·05-4·22) and patients with KRAS wild-type tumours (0·79, 0·61-1·03; pinteraction=0·08). Compared with placebo, patients allocated dacomitinib had significantly longer time to deterioration of cough (p<0·0001), dyspnoea (p=0·049), and pain (p=0·041). 185 (39%) of 477 patients who received dacomitinib and 86 (36%) of 239 patients who received placebo had serious adverse events. The most common grade 3-4 adverse events were diarrhoea (59 [12%] patients on dacomitinib vs no controls), acneiform rash (48 [10%] vs one [<1%]), oral mucositis (16 [3%] vs none), and fatigue (13 [3%] vs four [2%]). INTERPRETATION: Dacomitinib did not increase overall survival and cannot be recommended for treatment of patients with advanced non-small-cell lung cancer previously treated with chemotherapy and an EGFR tyrosine-kinase inhibitor. FUNDING: Canadian Cancer Society Research Institute and Pfizer.