Treatment Of EGFR-mutant Non-small Cell Lung Cancer Research Articles

Abstract 4756: Targeting DNA topoisomerase II to manage acquired resistance to third generation EGFR tyrosine kinase inhibitors in the treatment of EGFR mutant NSCLC

Abstract Development of effective strategies to manage the inevitable acquired resistance to osimertinib, a 3rd generation EGFR inhibitor with proven clinical efficacy in prolonging survival of patients with EGFR mutant (EGFRm) non-small cell lung cancer (NSCLC), is an urgent and critical area of unmet need in the clinic. Effort toward this direction led us to find that the DNA topoisomerase II (Topo II) inhibitors, doxorubicin and etoposide (VP-16), but not other chemotherapeutic agents, synergistically decreased the survival of osimertinib-resistant cell lines when combined with osimertinib. The combination of osimertinib with either doxorubcin or VP-16 effectively induced DNA damage and apoptosis in osimertinib-resistant cells, suppressed the growth of osimertinib-resistant tumors, and delayed the emergence of acquired resistance to osimertinib. Mechanistic studies found that osimertinib as well other EGFR-TKIs effectively decreased Topo IIα levels in EGFRm NSCLC cells by facilitating its proteasomal degradation and induced DNA damage; these effects were lost in cell lines with osimertinib acquired resistance that possessed elevated basal levels of Topo IIα. In the majority of EGFRm NSCLC tissues relapsed from EGFR-TKI treatment, Topo IIα levels were substantially increased. Enforced expression of ectopic TOP2A genes in sensitive EGFRm NSCLC cells conferred resistance to osimertinib in inducing DNA damage and apoptosis, whereas knockdown of TOP2A in osimertinib-resistant cell lines restored their responses to undergo osimertinib-induced DNA damage and apoptosis. Together, these results reveal a previously undiscovered essential role of Topo IIα modulation in regulating the responses of EGFRm NSCLC cells to osimertinib, providing scientific rationale for targeting Topo II to manage acquired resistance to osimertinib and possibly other third generation EGFR-TKIs, thus warranting clinical validation of this strategy. (This study was supported by NIH/NCI R01 CA223220 and UG1 CA233259 and Emory Winship Cancer Institute lung cancer research pilot funds). Citation Format: Zhen Chen, Karin A. Vallega, Dongsheng Wang, Zihan Quan, Songqing Fan, Qiming Wang, Ticiana A. Leal, Suresh S. Ramalingam, Shi-Yong Sun. Targeting DNA topoisomerase II to manage acquired resistance to third generation EGFR tyrosine kinase inhibitors in the treatment of EGFR mutant NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4756.

Clinical advances in EGFR-TKI combination therapy for EGFR-mutated NSCLC: a narrative review.

Mutations located in epidermal growth factor receptor (EGFR) tyrosine kinase domains have been described as the 'Achilles heel' of non-small cell lung cancer (NSCLC) and can be targeted by epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs). However, the clinical benefits of EGFR-TKIs are limited, and drug resistance inevitably occurs in NSCLC patients after long-term exposure to certain drugs. EGFR-TKI combination therapies, including combined targeted therapy, radiotherapy, chemotherapy, and immunotherapy, have shown promise in addressing this issue. This literature review analyzed the rationale and controversies of clinical research related to various EGFR-TKI combination therapies. The PubMed database was searched to retrieve articles published from January 1, 2001 to April 15, 2023 using the following Medical Subject Headings (MeSH) terms: "EGFR-mutated non-small cell lung cancer" and "clinical trial". Google Scholar was also reviewed to retrieve additional articles. The search was limited to articles published in English. In this review, we summarized EGFR-TKI combination therapies, including combined targeted therapy, radiotherapy, chemotherapy, and immunotherapy, most of which have shown efficacy and safety in patients with EGFR-mutated NSCLC. A number of clinical studies with large sample sizes have analyzed the activity and toxicity of combined therapies and explored potential and well-tolerated treatment options. EGFR mutations have been detected in many NSCLC patients and can be targeted by EGFR-TKIs. However, drug resistance after long-term exposure remains a significant challenge for this type of treatment. Most clinical trials have shown that the combination of EGFR-TKIs and targeted therapy, chemotherapy, radiotherapy or immunotherapy is efficacious and safe in the treatment of EGFR-mutated NSCLC. It should be noted that in some instances, serious adverse events have led to the termination of trials. However, EGFR-TKI combination therapy is indeed an effective approach for the treatment of patients with EGFR-mutated NSCLC and deserves further development.

GW4869 Can Inhibit Epithelial-Mesenchymal Transition and Extracellular HSP90α in Gefitinib-Sensitive NSCLC Cells.

GW4869 is an exosomal inhibitor. It is necessary to delay the occurrence of gefitinib resistance during non-small-cell lung cancer (NSCLC) treatment. This study aimed to investigate the anti-tumor effects of GW4869 on epithelial-mesenchymal transition (EMT) and expression of extracellular heat shock protein 90α (eHSP90α) that contributes to acquired resisitance. Our study provides a new sight into the treatment of EGFR-mutated NSCLC. We performed western blotting to detect levels of EMT and eHSP90α. Wound healing and transwell assays were performed to evaluate the behavioral dynamics of EMT. A nude mouse model of HCC827 was established in vivo. GW4869 inhibited the expression of eHSP90α, EMT, invasion and migration abilities of HCC827 and PC9. GW4869 enhanced sensitivity to gefitinib in BALB/c nude mice bearing tumors of HCC827. These studies suggest that GW4869 can inhibit EMT and extracellular HSP90α, providing new strategies for enhancing gefitinib sensitivity in NSCLC.

Abstract 1752: Darolutamide reverses osimertinib resistance in non-small cell lung cancer

Abstract Targeted therapies, such as EGFR inhibitors, have improved survival for patients with non-small cell lung cancer (NSCLC). Overall cure rates remain low due to eventual development of resistance. Osimertinib is a third-generation EGFR inhibitor that overcomes T790M-mediated resistance to earlier generation EGFRi. However, resistance to osimertinib has also emerged through mechanisms that are EGFR-dependent and EGFR-independent. To uncover novel strategies to overcome osimertinib resistance, we explored androgen receptor (AR) antagonists in combination with osimertinib as recent studies have demonstrated AR inhibition enhanced TKI-targeted therapy. For these experiments, we utilized lab-derived osimertinib-resistant PC9-AR and HCC827-AR NSCLC cell lines and matching parental lines in both in vitro and in vivo model systems. Clonogenic assays revealed that darolutamide in combination with osimertinib synergistically suppressed clonal growth in resistant cell lines. Similar results were observed with the combination of enzalutamide and osimertinib. Given this result, we next wanted to establish whether the promising in vitro activity of this combination translates into antitumor efficacy in vivo. Mice bearing either HCC827AR or PC9AR xenografts were treated orally daily with both drugs. At the doses administered, neither drug alone had antitumor activity. However, the combination significantly delayed tumor growth by more than 60%. We confirmed this ability to reverse resistance as a class effect using a different AR antagonist, enzalutamide in PC9AR-bearing mice. Significant tumor growth inhibition was observed with the combination of enzalutamide and osimertinib. To investigate the mechanism by which this combination may reverse osimertinib-resistance, RNA-seq studies were performed following drug exposure in vitro using parental and resistant cell lines under various experimental conditions. Comparison of gene expression profiles between parental and resistant cell lines under different therapeutic pressure and pathway enrichment analysis revealed important differentially expressed genes pointing plausible activated pathways that underline osimertinib resistance. AR antagonists have the potential to reverse EGFR inhibitor resistance in treatment of EGFR-mutant NSCLC. Citation Format: John C. Schmitz, Guojing Zhang, Zhentao Liu, Yufei Huang, Gabriel Sica, Shi-Yong Sun, Taofeek K. Owonikoko. Darolutamide reverses osimertinib resistance in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1752.

Examination of the effectiveness of local therapy for oligo-recurrence of EGFR-mutated NSCLC.

The effectiveness of local therapy has been reported in patients with oligo-recurrence of non-small cell lung cancer (NSCLC), a metachronous recurrence with a limited number of recurrences, which can be treated with local therapy. Conversely, remarkable progress has been made in systemic therapy for NSCLC with the advent of molecular targeted therapy. In particular, epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) are very effective in the treatment of EGFR-mutated NSCLC. There is currently no consensus on treatment for oligo-recurrence of EGFR-mutated NSCLC. From 2004 to 2014, 811 patients underwent complete resection for NSCLC at Kitasato University Hospital and, of these, 244 patients developed recurrence. Oligo-recurrence was defined as the presence of two or less recurrent lesions, and 34 patients presented with EGFR-mutated oligo-recurrence. We retrospectively examined and compared the effects of EGFR-TKIs with those of radical local therapy in patients with oligo-recurrent EGFR-mutated NSCLC. The five-year post-recurrence survival (PRS) rates of patients with EGFR-mutated oligo-recurrence who received radical local therapy (n=23) and those who did not (n=11) were 59.4 and 45.5%, respectively (p=0.777). Multivariate analysis revealed no favorable prognostic factors associated with prolonged PRS, and radical local therapies did not improve PRS in patients with oligo-recurrence (p=0.551). Radical local therapy did not affect PRS in patients with oligo-recurrent EGFR-mutated NSCLC. Even in cases of oligo-recurrence, the administration of local therapy in patients with EGFR-mutated NSCLC might be carefully considered.

Anti-angiogenesis revisited: reshaping the treatment landscape of advanced non-small cell lung cancer.

Although anti-angiogenic agents have been of limited use in the treatment of non-small cell lung cancer (NSCLC) until recently, further roles for the use of angiogenesis inhibition have emerged in the era of targeted therapy and immune checkpoint blockade. Given the shared common downstream signals of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) with their complementary roles in tumorigenesis and tumor angiogenesis, the dual inhibition of EGFR and VEGF pathways represents a rational strategy to maximize clinical efficacy and overcome resistance in the treatment of EGFR-mutant NSCLC. VEGF-driven angiogenesis is a potent driver of immunosuppressive tumor microenvironment (TME), with the recruited immunosuppressive cells driving angiogenesis, highlighting the interplay between the tumor vasculature and the anticancer immunity. Anti-angiogenic therapy can normalize the tumor vasculature and reprogram the TME from immunosuppressive into immunosupportive. Intensive research is under way to utilize the anti-angiogenic combination therapy to its full potential in diverse clinical settings in urgent unmet needs for the treatment of NSCLC. In this review, we present an overview of tumor angiogenesis and summarize the scientific background and preclinical and clinical evidence of anti-angiogenic therapy in combination with target therapy and immunotherapy for the treatment of NSCLC.

Lazertinib: on the Way to Its Throne.

Lazertinib is an oral, irreversible, third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) that forms an irreversible covalent bond to the Cys797 residue in the ATP-binding site of the EGFR kinase domain and exhibits a high selectivity for sensitizing and T790M EGFR mutations. In January 2021, it was first approved for the treatment of advanced or metastatic non-small cell lung cancer (NSCLC) patients with EGFR T790M who had previously received EGFR TKI therapy based on LASER201, a phase I/II trial. At a recommended dose of 240 mg, lazertinib achieved an encouraging anti-tumor activity in both extra- and intracranial lesions. With a high half-maximal inhibitory concentration for EGFR wildtype tumors, it is anticipated to pose a lower risk of skin and cardiac adverse events compared to osimertinib. Lazertinib is currently being investigated as a monotherapy in first-line treatment and in combination with amivantamab under various settings. In this review, we systematically summarize the preclinical and clinical data of lazertinib and discuss future perspectives on the treatment of EGFR-mutant NSCLC.

MA11.01 Development of Novel EGFR Mutant NSCLC Mouse Models and Murine Cell Lines: New Tools for NSCLC Research

EGFR mutant lung cancer accounts for approximately 15-30% of all non-small cell lung cancer (NSCLC) cases, with the prevalence varying in different populations. A point mutation L858R and in-frame deletions in exon 19 of the EGFR gene account for the majority of all EGFR activating mutations. EGFR tyrosine kinase inhibitors (TKIs) have led to significant advances in the treatment of EGFR mutant NSCLC; however, many patients show a partial response and all eventually develop resistance. Better preclinical models are required to design rational combination therapies. Our group has used syngeneic orthotopic mouse models of NSCLC to study interactions between cancer cells and the tumor microenvironment in the lung. These approaches are limited by the availability of murine lung cancer cell lines. To our knowledge, there are currently no EGFR mutant murine lung cancer cell lines. Therefore, we developed a novel transgenic mouse strain that conditionally expresses mutant EGFR mediated by Cre-recombinase. Administration of adeno-Cre virus into the lungs resulted in the development of EGFR-driven lung tumors. In collaboration with the Mouse Genetics Core at National Jewish Health, we developed two novel EGFR mutant mouse models (Rosa-loxP-STOP-LoxP- EGFR L860R/del19-mC3-WPRE): one with a deletion 19 and one with an L860R mutation (equivalent to the human L858R mutation) in the mouse EGFR gene. Tumors are initiated through intratracheal injections of the adeno-Cre virus. These mice were bred with p53flox mice from Jackson Laboratories to increase the diversity of tumors. Tumors were harvested and submitted to histological characterization by H&E staining or processed to create cell lines. These cell lines were characterized by in vitro growth assays, western blot analyses, and sequencing to confirm their genotype and responsiveness to EGFR TKIs. Cell lines were implanted into both the flanks and lungs of mice to determine their responsiveness to EGFR TKIs. Tumor-bearing mice were imaged by CT and treated by oral gavage with the EGFR TKIs. Intratracheal administration of adeno-Cre led to the development of multiple tumors throughout all lobes of the lung in both del19 and L860R mice. Time to tumor formation occurred within 4-12 weeks. Importantly, treatment of the mice with osimertinib resulted in tumor shrinkage and improvement in the health of mice. Moreover, we were able to successfully isolate 3 distinct cell lines (del19.1, del19.2, L860R.1) from these tumors. In vitro, these cell lines are responsive to multiple EGFR TKIs, as evidenced by a decrease in proliferation and inhibition of phospho-ERK. These cells form tumors when implanted into the flanks of nu/nu mice, del19.1-derived tumors undergo shrinkage in response to osimertinib. Orthotopically injected del19.1 cells form tumors in the left lungs of WT C57Bl/6 mice. We have developed novel mouse models as well as murine cell lines that reflect mutant EGFR-driven NSCLC which will be useful tools for studying NSCLC both in vitro and in vivo. By increasing the number of murine NSCLC cell lines, we can better recapitulate human disease to increase our understanding of NSCLC and develop novel therapeutic strategies that can be used to treat patients.

An overview of osimertinib as a treatment of non-small cell lung cancer (NSCLC): an update

ABSTRACT Introduction: Osimertinib is a third-generation anti-epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), that irreversibly binds to mutant EGFR, specifically to the T790M EGFR mutant non-small cell lung cancer (NSCLC). Since its approval, osimertinib has been tested in multiple scenarios, including the first-line and adjuvant setting of EGFR-mutant disease. Areas covered: The authors summarize the most recent evidence about osimertinib in NSCLC, covering its use as a first-line therapy, its activity on central nervous system metastatic disease, and in elderly patients. Moreover, the authors focus on resistance to this drug and on the therapeutic strategies that may be used to overcome this issue. Expert opinion: Osimertinib is a key player in the treatment ofEGFR mutant NSCLC and will probably be used in earlier clinical settings in the future, giving rise to an emerging variety of resistance mechanisms. These could be potentially overcome in several ways: e.g. as an oligo-progressive disease local therapy, maintaining osimertinib might be a reasonable option; however, for widespread progressive disease, a switch to chemotherapy should be considered. Finally, either liquid biopsy or tissue biopsy might be considered in patients progressing to osimertinib, as they can lead to the identification of potentially targetable resistance mechanisms.

Resistance to epidermal growth factor receptor tyrosine kinase inhibitors in mutated non-small cell lung cancer: new avenues and strategies to overcome resistance

The most common driver mutation in non-small cell lung cancer (NSCLC) is found within the tyrosine kinase domain of the epidermal growth factor receptor (EGFR). It commonly affects younger, female, and non-smoking patients. To date, there are five approved tyrosine kinase inhibitors (TKIs) for the treatment of EGFR-mutated NSCLC: erlotinib, gefitinib, the second-generation TKI afatinib and dacomitinib, and the third-generation TKI osimertinib. Sequencing TKI treatment or starting with osimertinib first are reasonable treatment strategies. Nevertheless, patients develop resistance to these TKIs, which can be primary or acquired. Primary resistance includes resistance mutations such as EGFR insertion 20, acquired resistance comprises the development of resistance mutations, activation of bypass signaling, or histological transformation into small cell lung cancer. This article summarizes the current landscape of treatment in EGFR-mutated lung cancer and discusses the different resistance mechanisms. It gives a perspective on novel EGFR TKIs and potential combination strategies to overcome resistance.

Treatment in EGFR-mutated non-small cell lung cancer: how to block the receptor and overcome resistance mechanisms.

In non-small cell lung cancer (NSCLC), the identification of epidermal growth factor receptor (EGFR) mutations and the parallel development of EGFR tyrosine kinase inhibitors (TKIs) have radically changed the therapeutic management strategies. Currently, erlotinib, gefitinib, and afatinib are all approved as standard first-line treatment in EGFR-mutated NSCLC. However, despite the proven efficacy, some EGFR-mutated NSCLCs do not respond to EGFR TKIs, while some patients, after a favorable and prolonged response to EGFR TKIs, inevitably progress within about 10-14 months. Epidermal growth factor receptor-dependent mechanisms, activation of alternative pathways, or phenotypic transformation can cause the resistance to EGFR TKIs. The exon 20 p.Thr790Met point mutation (T790M) is responsible for about 60% of cases of resistance when progression occurs. A third-generation TKI, osimertinib, improved outcome in patients harboring T790M after first- and second-generation TKI treatment. However, resistance develops even after treatment with third-generation drugs. To date, the Cys797Ser (C797S) mutation in exon 20 of EGFR is the most well-known resistance mutation after osimertinib. Fourth-generation TKIs are already under development. Nevertheless, additional information is needed to better understand and effectively overcome resistance. The aim of this review is to report recent advances and future perspectives in the treatment of EGFR-mutated NSCLC, highlighting the resistance mechanisms that underlie disease progression.

Erlotinib, cabozantinib, or erlotinib plus cabozantinib as second-line or third-line treatment of patients with EGFR wild-type advanced non-small-cell lung cancer (ECOG-ACRIN 1512): a randomised, controlled, open-label, multicentre, phase 2 trial

SummaryBackgroundErlotinib is approved for the treatment of all patients with advanced non-small cell lung cancer (NSCLC), but is most active in the treatment of EGFR mutant NSCLC. Cabozantinib, a small molecule tyrosine kinase inhibitor, targets MET, VEGFR, RET, ROS1, and AXL, which are implicated in lung cancer tumorigenesis. We tested the efficacy of cabozantinib and the combination of erlotinib plus cabozantinib, as compared with erlotinib, in patients with EGFR wild-type NSCLC.MethodsIn this three arm, randomised phase 2 study, the primary endpoint was to compare progression-free survival (PFS) of patients treated with cabozantinib versus erlotinib alone, and the combination of erlotinib plus cabozantinib versus erlotinib alone. Patients were eligible if they had received 1–2 previous treatments for advanced non-squamous EGFR wild-type NSCLC. Patients were stratified by performance status and line of therapy, then randomised using permuted blocks within strata to receive open label oral daily dosing of erlotinib (150 mg), cabozantinib (60 mg), or erlotinib (150 mg) and cabozantinib (40 mg). Imaging was performed every 8 weeks. At the time of radiographic progression, there was optional crossover for patients in either single agent arm to receive combination therapy. The comparison between erlotinib and each of the arms was powered (91%) to detect a PFS hazard ratio (HR) of 0.5 (1-sided p-value 0.10-level). Secondary objectives were overall survival (OS), radiographic response by RECIST version 1.1 and description of adverse events by CTCAE version 4.0. This trial is registered with ClinicalTrials.gov, number NCT01708954.FindingsAt complete enrollment, we randomised 125 patients (42 assigned to erlotinib, 40 assigned to cabozantinib, 43 assigned to the combination), of which 111 (89%) were eligible and received treatment per protocol were included in the primary analysis (38, 38, and 35 patients on erlotinib, cabozantinib, and combination, respectively). Compared to erlotinib alone (median 1.8 months), PFS was significantly improved in the cabozantinib arm (4.3 months, HR 0.39, 1-sided p=0.0003, 80% CI 0.27–0.55) and also in the erlotinib plus cabozantinib arm (4.7 months, HR 0.37, 1-sided p=0.0003, 80% CI 0.25–0.53).The safety analysis population included all patients who received study therapy regardless of eligibility. The most common grade 3 or 4 adverse events were diarrhea (3 [8%] in the erlotinib group vs 3 [8%] in the cabozantinib group vs 11 [28%] in the erlotinib and cabozantinib group), hypertension (none vs 10 [25%] vs 1 [3%]), fatigue (5 [13%] vs 6 [15%] vs 6 [15%]), oral mucositis (none vs 4 [10%] vs 1 [3%]), and thromboembolic event (none vs 3 [8%] vs 2 [5%]). Adverse events that were grade 3 or worse occurred in 13 (33%) patients in the erlotinib group, in 28 (70%) patients in the cabozantinib group, and in 28 (72%) patients in the erlotinib and cabozantinib group. One death of respiratory failure occurred in the cabozantinib group, deemed possibly related to either drug or disease, and one death occurred in the erlotinib plus cabozantinib group from pneumonitis. MET IHC results were available on 86 patients from the primary analysis and 85% were scored as positive (1–3+ membrane or cytoplasm staining with MET4 antibody). There was no association between MET IHC status and PFS when treated with or without cabozantinib.InterpretationThe ECOG-ACRIN 1512 trial design tested the feasibility of using cabozantinib alone or combined with erlotinib in this patient population with EGFR wild-type NSCLC. Despite its modest sample size, this trial identified signals of clinically meaningful efficacy superior to that of erlotinib alone, and additional toxicity that was generally manageable. Cabozantinib-based regimens are promising for further investigation in this patient population.

Liquid biopsy in non-small cell lung cancer: come of age

With understanding of lung cancer biology and advances in technology, treatment for advanced non-small cell lung cancer (NSCLC) is currently guided according to the genetic abnormalities, including epidermal growth factor receptor (EGFR) mutation, translocation in ALK, ROS1 or RET, B-raf mutation, etc. In the treatment of EGFR-mutated NSCLC, EGFR tyrosine kinase inhibitors (TKIs) are recommended as first-line therapy based on high response rates and longer progression free survival (PFS) compared to platinum-doublet chemotherapy (1-3).

Treatment of Isolated Intracranial Progression of Lung Cancer During Treatment with Systemic Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors (EGFR-TKIs)

Background: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are an effective treatment for non-small-cell lung cancer (NSCLC) harbouring EGFR mutations. The development of isolated central nervous system (CNS) metastases is a relevant clinical problem in patients who respond well to EGFR-TKIs. Methods: We present a patient with isolated progression of brain metastases during treatment of EGFRmutated NSCLC with an EGFR-TKI and review the treatment options in this setting, including the evidence for and toxicity of treatment with high-dose TKIs. Results: Oligometastatic CNS progression during TKI therapy may be treated locally. Both whole brain radiotherapy (WBRT) and stereotactic brain irradiation are well tolerated and effective in this setting. The use of high-dose pulsed TKIs is intended to increase the concentration of TKI in the brain and has been reported to be effective and without significant toxicity in case reports and small case series. These therapeutic options are illustrated in the case of a 44-year-old NSCLC patient who developed CNS progression after WBRT during second-line erlotinib and was treated locally with stereotactic radiosurgery (SRS) and, upon further CNS progression, with high-dose pulsed erlotinib. This resulted in intracerebral response; however, significant haemorrhage also occurred. Severe haemorrhage has not previously been described as a complication of high-dose pulsed erlotinib. Conclusion: Possible explanations for isolated CNS progression during TKI treatment include inadequate dosing across the blood—brain barrier and longer survival on TKIs. The efficacy and tolerability of high- dose pulsed TKIs for CNS metastases has been previously reported. None of the cases reported showed the severe haemorrhage and cerebral oedema that developed in our patient. Simultaneous anticoagulation as well as previous SRS may have predisposed our patient to haemorrhage and may prove to be relative contraindications to high-dose pulsed erlotinib. Most centres only see a few patients in this clinical situation, and co-operative efforts are needed to collect and analyse similar cases and to develop appropriate treatment strategies.

Prospective cohort study of serum sialylated glycoprotein (KL-6) as a prognostic marker in patients (pts) with non-small cell lung cancer (NSCLC) receiving gefitinib monotherapy: Okayama Lung Cancer Study Group 0703.

e19023 Background: Gefitinib is now crucial in the treatment of EGFR-mutant NSCLC. Its anti-tumor activity could be modulated by MUC1 mucins [Cancer Res 2006], similar to KL-6 in the biochemical property, currently used as an indicator for interstitial lung diseases (ILDs). Our preliminary retrospective study showed the elevated serum KL-6 level is a potential negative prognostic value in pts with advanced NSCLC receiving gefitinib therapy [Lung Cancer 2008]. We conducted an observational study to evaluate this issue prospectively. Methods: Consecutive, EGFR-TKI-naïve NSCLC pts who were to receive gefitinib were enrolled and stratified by pretreatment KL-6 levels (< 500 U/ml: normal group [NG] and ≥ 500 U/ml: abnormally elevated group [EG]). The primary endpoint was overall survival (OS). The planned accrual number of pts was 150, assuming an estimated HR of 2.0, α=0.05, ß=0.10). We also evaluated ILD events during the gefitinib treatment. Results: Between 2007 and 2012, 154 pts were registered (NG: 89 [58%] and EG: 65 [42%] with median KL-6 score of 305 and 1,050 IU/mL, respectively). Those with pretreatment pulmonary fibrosis were similarly distributed between the groups. Median follow-up time was 13.7 months. The EG had significantly worse OS in the univariate analysis (log-rank p=0.0011), which was retained in the multivariate analysis (hazard ratio [HR]: 1.95, 95% confidence interval [95% CI]: 1.34-2.81). Exploratory analyses showed an interaction between EGFR-mutation status and KL-6; HR of KL-6 for OS: 1.96, [1.30-2.97], and HR: 4.80, [1.05-21.95] in pts with EGFR-mutant and wild-typed tumors, respectively (interaction p=0.07). As for ILD event it occurred similarly during the gefitinib therapy (HR: 2.76, [0.62-12.33]). Conclusions: The elevated KL-6 level could predict a poor prognosis in NSCLC pts with gefitinib therapy, and this association seemed modulated by EGFR-mutation status. Further studies are needed to clarify the biological behavior of KL-6 expression on tumor progression especially in the EGFR pathway.