pf-00299804 and Glioblastoma

Standard treatment of newly diagnosed glioblastoma (GB) is surgery with radiotherapy and temozolomide, but tumors will recur with a median overall survival of only 15 months. It seems imperative to explore new possibilities of treatment based on targetable alterations known to be present in GB. Among others, Epidermal Growth Factor Receptor or EGFR (HER1) mutations or amplifications are the most prevalent alterations in GB. In fact, around 40% of GB cases show amplification of EGFR gene, and half of these patients carry the EGFRvIII mutation, a deletion that generates a continuous activation of the tyrosine kinase domain of the receptor. Areas covered: We review the current knowledge about Dacomitinib, an oral, irreversible, second-generation, pan-HER tyrosine kinase inhibitor, in the treatment of glioblastoma. Dacomitinib has noteworthy antiglioma activity in preclinical models and has been tested in one phase II trial in patients with recurrent GB with EGFR amplification. Expert opinion: Despite the poor global results of Dacomitinib in recurrent GB shown in a phase II trial, some patients had a significant benefit. Therefore, it is necessary to improve the knowledge about the mechanisms of failure or resistance to EGFR inhibitors in GB.

Topics: Animals; Drugs, Investigational; ErbB Receptors; Gene Amplification; Glioblastoma; Humans; Mutation; Neoplasm Recurrence, Local; Protein Kinase Inhibitors; Quinazolinones; Survival Rate

We conducted a multicenter, 2-stage, open-label, phase II trial to assess the efficacy and safety of dacomitinib in adult patients with recurrent glioblastoma (GB) and epidermal growth factor receptor gene (EGFR) amplification with or without variant III (EGFRvIII) deletion.. Patients with first recurrence were enrolled in 2 cohorts. Cohort A included patients with EGFR gene amplification without EGFRvIII mutation. Cohort B included patients with EGFR gene amplification and EGFRvIII mutation. Dacomitinib was administered (45 mg/day) until disease progression/unacceptable adverse events (AEs). Primary endpoint was progression-free survival (PFS; RANO criteria) at 6 months (PFS6).. Thirty patients in Cohort A and 19 in Cohort B were enrolled. Median age was 59 years (range 39-81), 65.3% were male, and Eastern Cooperative Oncology Group Performance Status 0/1/2 were 10.2%/65.3%/24.5%, respectively. PFS6 was 10.6% (Cohort A: 13.3%; Cohort B: 5.9%) with a median PFS of 2.7 months (Cohort A: 2.7 mo; Cohort B: 2.6 mo). Four patients were progression free at 6 months and 3 patients were so at 12 months. Median overall survival was 7.4 months (Cohort A: 7.8 mo; Cohort B: 6.7 mo). The best overall response included 1 complete response and 2 partial responses (4.1%). Stable disease was observed in 12 patients (24.5%: eight in Cohort A and four in Cohort B). Diarrhea and rash were the most common AEs; 20 (40.8%) patients experienced grade 3-4 drug-related AEs.. Dacomitinib has a limited single-agent activity in recurrent GB with EGFR amplification. The detailed molecular characterization of the 4 patients with response in this trial can be useful to select patients who could benefit from dacomitinib.

Topics: Adult; Aged; Aged, 80 and over; Brain Neoplasms; ErbB Receptors; Female; Follow-Up Studies; Gene Amplification; Gene Expression Regulation, Neoplastic; Glioblastoma; Humans; Male; Middle Aged; Mutation; Prognosis; Quinazolinones; Signal Transduction; Survival Rate

Intratumoural heterogeneity underlies tumour escape from molecularly targeted therapy in glioblastoma. A cell-based model preserving the evolving molecular profiles of a tumour during treatment is key to understanding the recurrence mechanisms and development of strategies to overcome resistance. In this study, we established a matched pair of glioblastoma stem-like cell (GSC) cultures from patient glioblastoma samples before and after epidermal growth factor receptor (EGFR)-targeted therapy. A patient with recurrent glioblastoma (MGG70R) harboring focal, high-level EGFR amplification received the irreversible EGFR tyrosine kinase inhibitor dacomitinib. The tumour that subsequently recurred (MGG70RR) showed diploid EGFR, suggesting inhibitor-mediated elimination of EGFR-amplified tumour cells and propagation of EGFR non-amplified cell subpopulations. The MGG70R-GSC line established from MGG70R formed xenografts retaining EGFR amplification and EGFR overexpression, while MGG70RR-GSC established from MGG70RR generated tumours that lacked EGFR amplification and EGFR overexpression. MGG70R-GSC-derived intracranial xenografts were more proliferative than MGG70RR-GSC xenografts, which had upregulated mesenchymal markers, mirroring the pathological observation in the corresponding patient tumours. In vitro MGG70R-GSC was more sensitive to EGFR inhibitors than MGG70RR-GSC. Thus, these molecularly distinct GSC lines recapitulated the subpopulation alteration that occurred during glioblastoma evasion of targeted therapy, and offer a valuable model facilitating therapeutic development for recurrent glioblastoma.

Topics: Animals; Brain Neoplasms; ErbB Receptors; Glioblastoma; Glioma; Heterografts; Humans; Mice; Molecular Targeted Therapy; Neoplasm Recurrence, Local; Quinazolinones; Tumor Cells, Cultured

Glioblastoma in adults, and medulloblastoma and pineoblastoma that mainly affect children, are aggressive brain tumors. The survival for patients with glioblastoma remains dismal. While the cure rate for medulloblastoma exceeds 70%, this figure has stagnated over the past few decades and survivors still contend with significant long-term debilitating side effects. The prognosis for pineoblastoma is age-dependent, with little chance of a cure for children younger than three years. More effective molecularly targeted strategies are urgently required to treat these cancers. Hyper-activation of epidermal growth factor receptor (EGFR) signaling is characteristic of several different classes of human cancers, including a subset of glioblastoma and medulloblastoma. This has provided the impetus for the development of a suite of EGFR pathway blockers, including second generation irreversible inhibitors, such as dacomitinib. We have developed a comprehensive drug evaluation pipeline, including in vitro interaction analyses and orthotopic xenograft mouse models, to address the efficacy of drugs for brain tumor treatment, enabling the exclusion of potentially ineffective treatments and prioritization of truly beneficial novel treatments for clinical trial. We used this system to examine the effects of dacomitinib as a single agent, or in combination with conventional chemotherapeutics, on the growth of human adult and pediatric brain tumor cell lines. Dacomitinib inhibited EGFR or EGFRvIII activity in vitro in all three tumor types tested, and as a single agent induced a modest increase in survival time for mice bearing glioblastoma, which accurately predicted human clinical trial data. For pediatric medulloblastoma, dacomitinib blocked EGFR/HER signalling in orthotopic xenografts and extended median survival as a single agent, however was antagonistic when used in combination with standard frontline medulloblastoma chemotherapies. The findings caution against the use of dacomitinib for pediatric brain tumor clinical trials.

Topics: Adult; Animals; Brain Neoplasms; Cell Line, Tumor; Child; ErbB Receptors; Female; Glioblastoma; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Quinazolinones; Signal Transduction

Biopsy is often used to investigate brain tumour-specific abnormalities so that treatments can be appropriately tailored. Dacomitinib (PF-00299804) is a tyrosine kinase inhibitor (TKI), which is predicted to only be effective in cancers where the targets of this drug (EGFR, ERBB2, ERBB4) are abnormally active. Here we describe a method by which serial biopsy can be used to validate response to dacomitinib treatment in vivo using a mouse glioblastoma model. In order to determine the feasibility of conducting serial brain biopsies in mouse models with minimal morbidity, and if successful, investigate whether this can facilitate evaluation of chemotherapeutic response, an orthotopic model of glioblastoma was used. Immunodeficient mice received cortical implants of the human glioblastoma cell line, U87MG, modified to express the constitutively-active EGFR mutant, EGFRvIII, GFP and luciferase. Tumour growth was monitored using bioluminescence imaging. Upon attainment of a moderate tumour size, free-hand biopsy was performed on a subgroup of animals. Animal monitoring using a neurological severity score (NSS) showed that all mice survived the procedure with minimal perioperative morbidity and recovered to similar levels as controls over a period of five days. The technique was used to evaluate dacomitinib-mediated inhibition of EGFRvIII two hours after drug administration. We show that serial tissue samples can be obtained, that the samples retain histological features of the tumour, and are of sufficient quality to determine response to treatment. This approach represents a significant advance in murine brain surgery that may be applicable to other brain tumour models. Importantly, the methodology has the potential to accelerate the preclinical in vivo drug screening process.

Topics: Animals; Antineoplastic Agents; Biopsy; Brain; Brain Neoplasms; Cell Line, Tumor; Glioblastoma; Humans; Immunohistochemistry; Mice, Inbred BALB C; Mice, Nude; Protein Kinase Inhibitors; Quinazolinones; Severity of Illness Index; Xenograft Model Antitumor Assays

Glioblastomas (GBM) are devastating tumors in which there has been little clinical improvement in the last decades. New molecularly directed therapies are under development. EGFR is one of the most promising targets, as this receptor is mutated and/or overexpressed in nearly half of the GBMs. However, the results obtained with first-generation tyrosine-kinase inhibitors have been disappointing with no clear predictive markers of tumor response. Here, we have tested the antitumoral efficacy of a second-generation inhibitor, dacomitinib (PF299804, Pfizer), that binds in an irreversible way to the receptor. Our results confirm that dacomitinib has an effect on cell viability, self-renewal, and proliferation in EGFR-amplified ± EGFRvIII GBM cells. Moreover, systemic administration of dacomitinib strongly impaired the in vivo tumor growth rate of these EGFR-amplified cell lines, with a decrease in the expression of stem cell-related markers. However, continuous administration of the compound was required to maintain the antitumor effect. The data presented here confirm that dacomitinib clearly affects receptor signaling in vivo and that its strong antitumoral effect is independent of the presence of mutant receptor isoforms although it could be affected by the PTEN status (as it is less effective in a PTEN-deleted GBM line). Dacomitinib is being tested in second line for EGFR-amplified GBMs. We hope that our results could help to select retrospectively molecular determinants of this response and to implement future trials with dacomitinib (alone or in combination with other inhibitors) in newly diagnosed GBMs.

Topics: Animals; Blotting, Western; Cell Survival; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; ErbB Receptors; Gene Amplification; Glioblastoma; Humans; Mice, Nude; Phosphorylation; Quinazolinones; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Survival Analysis; Time Factors; Tumor Burden; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

A novel pan ERBB inhibitor PF-00299804 (dacomitinib) is currently in phase II clinical trials in glioblastoma multiforme (GBM) patients; however its pre-clinical efficacy in GBMs has not been tested. In this study, we evaluated the efficacy of dacomitinib alone or in combination with PI3K/mTOR dual inhibitor PF-05212384 in GBM and assessed the mechanisms of resistance and the molecular determinants of response. A panel of established and patient derived primary GBM lines that present different molecular profiles and also the GBM lines engineered to express EGFRvIII mutant or PTEN were treated with either dacomitinib, PF-05212384, or combination and assessed for their viability and changes in EGFR/PI3K/mTOR signaling. We show that dacomitinib significantly reduced phosphorylated EGFR in all the GBM lines but did not show a dose-dependent response on cell viability in a majority of the lines tested. Multiple lesions in the receptor tyrosine kinases (RTKs) pathway including PTEN mutation, co-activation of RTKs, and EGFRvIII mutation resulted in unaltered active status of PI3K/mTOR in the GBM lines even in the presence of EGFR inhibition. Blocking PI3K/mTOR dramatically inhibited cell proliferation in most GBM lines and enhanced dacomitinib induction of apoptosis in a GBM line that has both EGFR amplification and EGFR-independent PI3K activation. These data suggest molecular profiling of EGFR/PI3K/PTEN status to select GBM patients for EGFR or/and PI3K/mTOR targeted therapies.

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Survival; Drug Screening Assays, Antitumor; Drug Synergism; ErbB Receptors; Glioblastoma; Humans; Morpholines; Mutation; Oncogene Proteins v-erbB; Phosphoinositide-3 Kinase Inhibitors; Quinazolinones; Signal Transduction; TOR Serine-Threonine Kinases; Triazines