Initial Tyrosine Kinase Inhibitors Treatment Research Articles

Programmed Cell Death Protein 1 Inhibitors and MET Targeted Therapies in NSCLC With MET Exon 14 Skipping Mutations: Efficacy and Toxicity as Sequential Therapies

IntroductionNSCLC with MET exon 14 skipping mutation (METex14) is associated with poor outcomes. Integration of novel targeted therapies is challenging because of barriers in testing and drug access. We, therefore, sought to characterize the treatment patterns, outcomes, and emerging issues of treatment sequencing in patients with METex14-mutant NSCLC. MethodsWe reviewed all NSCLC cases with METex14 alterations between 2014 and 2020 across four Canadian cancer centers. Demographics, disease characteristics, systemic therapy, overall response rates (ORRs), survival, and toxicity were summarized. ResultsAmong 64 patients with METex14-mutant NSCLC, the median overall survival was 23.1 months: 127.0 months in stage 1, 27.3 months in resected stage 2 and 3, and 16.6 months in unresectable stage 3 or 4 disease, respectively. In patients with advanced disease, 22% were too unwell for systemic treatment. MET tyrosine kinase inhibitors (TKIs) were administered to 28 patients with an ORR of 33%, median progression-free survival of 2.7 months, and 3.8 months for selective TKIs. Programmed cell death protein-1 (PD-1) inhibitors were given to 25 patients—the ORR was 44% and progression-free survival was 10.6 months. No responses were seen with subsequent MET TKIs after initial TKI treatment. Grade 3 or higher toxicities occurred in 64% of patients who received MET TKI after PD-1 inhibitors versus 8% in those who did not receive PD-1 inhibitors. ConclusionsMany patients with advanced METex14 NSCLC were too unwell to receive treatment. PD-1 inhibitors seem effective as an initial treatment, although greater toxicity was seen with subsequent MET TKIs. Thus, timely testing for METex14 skipping and initial therapy are imperative to improving patient survival.

ALK Inhibitor Treatment Patterns and Outcomes in Real-World Patients with ALK-Positive Non-Small-Cell Lung Cancer: A Retrospective Cohort Study.

Randomized trials have demonstrated that anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKIs) can be safe and efficacious treatments for patients with ALK-positive advanced non-small-cell lung cancer (aNSCLC). However, their safety, tolerability, effectiveness, and patterns of use in real-world patients remain understudied. We sought to assess the overall treatment pattern characteristics, safety, and effectiveness outcomes of real-world patients with ALK-positive aNSCLC receiving ALK TKIs. This retrospective cohort study using electronic health record data included adult patients with ALK-positive aNSCLC receiving ALK TKIs between January 2012 and November 2021 at a large tertiary medical center, University of California, San Francisco (UCSF), with alectinib or crizotinib as the initial ALK TKI therapy. Our primary endpoints included the incidence of treatment changes (treatment dose adjustments, interruptions, and discontinuations) during the initial ALK TKI treatment, the count and type of subsequent treatments, rates of serious adverse events (sAEs), and major adverse events (mAEs) leading to any ALK TKI treatment changes. Secondary endpoints included the hazard ratios (HRs) for median mAE-free survival (mAEFS), real-world progression-free survival (rwPFS), and overall survival (OS) when comparing alectinib with crizotinib. The cohort consisted of 117 adult patients (70 alectinib and 47 crizotinib) with ALK-positive aNSCLC, with 24.8%, 17.9%, and 6.0% experiencing treatment dose adjustments, interruptions, and discontinuation, respectively. Of the 73 patients whose ALK TKI treatments were discontinued, 68 received subsequent treatments including newer generations of ALK TKIs, immune checkpoint inhibitors, and chemotherapies. The most common mAEs were rash (9.9%) and bradycardia (7.0%) for alectinib and liver toxicity (19.1%) for crizotinib. The most common sAEs were pericardial effusion (5.6%) and pleural effusion (5.6%) for alectinib and pulmonary embolism (6.4%) for crizotinib. Patients receiving alectinib versus crizotinib as their first ALK TKI treatment experienced significantly prolonged median rwPFS (29.3 versus 10.4months) with an HR of 0.38 (95% CI 0.21-0.67), while prolonged median mAEFS (not reached versus 91.3months) and OS (54.1 versus 45.8months) were observed in patients receiving alectinib versus crizotinib but did not reach statistical significance. Yet, it is worth noting that there was a high degree of cross-over post-progression, which could significantly confound the overall survival measures. We found that ALK TKIs were highly tolerable, and alectinib was associated with favorable survival outcomes with longer time to adverse events (AE) requiring medical interventions, disease progression, and death, in the context of real-world use. Proactive monitoring for adverse events such as rash, bradycardia, and hepatotoxicity may help further promote the safe and optimal use of ALK TKIs in the treatment of patients with aNSCLC.

Rechallenge with Multi-Targeted Tyrosine Kinase Inhibitors in Patients with Advanced Soft Tissue Sarcoma: A Single-Center Experience.

PurposeChemotherapy and multi-targeted tyrosine kinase inhibitors (TKI) are important treatments for advanced soft tissue sarcomas, but the following treatment remains unclear after the failure of these drugs. This retrospective study investigated the efficacy and safety of multi-targeted TKI rechallenge in patients with advanced soft tissue sarcoma after the failure of previous TKI treatment.Patients and MethodsGastrointestinal stromal tumors, dermatofibrosarcoma protuberans and anaplastic lymphoma kinase translocation-positive inflammatory myofibroblastic tumor were excluded. Eligible patients included those diagnosed with advanced soft tissue sarcoma, progressed after the initial TKI treatment, and received the same or other TKI therapies. Treatment response, adverse events, median progression-free survival and overall survival were analyzed.ResultsTwenty-six eligible patients were included. Nineteen patients had previously received chemotherapy, and all patients had received at least 1.5 months of initial TKI treatment. During the TKI rechallenge, patients were treated with anlotinib (n =16), lenvatinib (n =3), apatinib (n =2), pazopanib (n =2), axitinib (n =2) or regorafenib (n =1). No patients achieved responses. Nine (34.6%) patients had stable disease confirmed by a second imaging scan, and 5 (19.2%) patients had stable disease that was not confirmed by a second scan. The estimated median progression-free survival and overall survival were 3.3 months and 11.7 months, respectively. Grade 3/4 adverse events occurred in 6 (23.1%) patients and were manageable.ConclusionOur findings suggest that multi-targeted TKI rechallenge may provide potential clinical benefits for patients with advanced soft tissue sarcoma after their previous TKI treatment.

Prognostic Effects of Pretreatment Statuses at Diagnosis in Patients with Chronic Myeloid Leukemia: Results of the New Target Observational Study 1

Prognostic Effects of Pretreatment Statuses at Diagnosis in Patients with Chronic Myeloid Leukemia: Results of the New Target Observational Study 1

Assessment of Treatment Patterns and Adverse Events Among Patients with Chronic Myeloid Leukemia Using Tyrosine Kinase Inhibitors

INTRODUCTIONChronic myeloid leukemia (CML), a myeloproliferative neoplasm is primarily treated using tyrosine kinase inhibitors (TKIs). Several next-generation TKIs (dasatinib, nilotinib, bosutinib, ponatinib) have been approved since the first approval of imatinib in 2002. With varying safety profiles, data on non-trial long-term TKI use and associated adverse events (AE) can aid in clinical decision making. Using population based data sources the current study assessed treatment patterns and AEs in a non-trial setting among TKI users with CML. METHODSA retrospective cohort analysis was conducted using MarketScan Commercial, and Supplemental Medicare databases (2012-2016). Data includes details on medical (e.g., date of diagnosis, diagnosis codes, procedures) and pharmacy (e.g., drug dose, duration, strength) utilization for over 90 million individuals enrolled in employer-sponsored health-plans in the US. Patients with a prescription claim for TKI along with at least 2 medical claims on separate dates with a diagnosis code for CML (ICD-9-CM: 205.10 - 205.12; ICD-10: C92.10-C92.12) were selected. Patients were aged ≥18 years at TKI initiation and had continuous health plan enrollment ≥6 months before and ≥6 months after TKI initiation. Patients were followed from TKI initiation until health plan disenrollment or end of database, whichever occurred earlier (defines follow-up period). TKI treatment patterns including initial dose, initial and total TKI treatment duration, treatment switching and discontinuation were assessed. Frequency and proportion for incident (i.e. newly observed conditions) AEs including rash, bleeding, gastrointestinal disorders (nausea, vomiting, diarrhea), tumor lysis syndrome and cardiovascular events (CHF, arrhythmia, peripheral arterial occlusive disease, cerebrovascular events) and post-AE outcomes (switching, discontinuation, dose reduction) were assessed. AE list was developed based on commonly reported events in clinical trials involving TKIs for CML and clinical judgement. All analyses were descriptive in nature. RESULTSStudy included 2,213 CML patients with mean age (standard deviation [SD]) of 55 (15) years, of which 55% were male and 55% had ≥2 co-morbid conditions. Post CML diagnosis, first-line of TKI initiated was imatinib (41%), dasatinib (36%), nilotinib (22%), and bosutinib and ponatinib (1% each). The average (SD) follow-up duration post TKI initiation was 607 (442) days. Mean (SD) duration of first-line TKI prescription was 392 (383) days. 61% of patients continued initial TKI during the follow-up period, 7% discontinued and 32% switched/re-initiated TKI (Figure 1). 39.2% patients had at least 1 incident AE while on index TKI therapy. GI disorders (20.4%) were the most commonly observed AE, followed by cardiovascular events (14.6%), rash (8.4%), bleeding (8.0%), and TLS (0.2%). The average (SD) time to GI disorders, bleeding, cardiovascular event, rash, and TLS was 242 (274) days, 238 (272) days, 219 (261) days, 222 (255) days, and 223 (285) days, respectively. The rates of discontinuation, treatment switch or dose reduction were largely similar across all AEs (Figure 2).The mean duration on any TKI (all-lines of therapy) was 561 (438) days. The most commonly observed AEs on while of TKI therapy (irrespective of line of therapy) were GI disorders (24.7%), followed by cardiovascular events (17.3%), rash (11.5%), bleeding (10.1%) and TLS (0.5%). CONCLUSIONSThe study helps address the current literature gap of long-term treatment patterns and AE among patients with CML using TKIs in a non-clinical trial setting. During follow-up 46% patients experienced at least 1 incident AE while on TKI therapy. Majority of patients (61%) continued same TKI therapy following AE. The type and rate of AE were similar following first-line therapy and anytime on TKI (any-line) during the follow-up period. Study results may not be comparable to clinical trial findings due to certain limitations; e.g., this study did not capture all adverse events but assessed incident AE based on a pre-specified list. Also, due to limitations of administrative claims data, assessment of AE grade was not feasible. However, findings from this study can complement clinical trial data in selection of TKIs for long-term use in real-world setting and can also be of value in selecting TKIs for future clinical studies involving novel combinations in CML. [Display omitted] DisclosuresKarve:AbbVie: Employment, Equity Ownership. Huang:ZS Associates: Employment; Novo Nordisk Inc: Equity Ownership; AstraZeneca: Research Funding. Ranade:ZS Associates: Employment. Porwal:ZS Associates: Employment. Desai:AbbVie: Employment, Equity Ownership. Rosenberg:AbbVie: Employment, Equity Ownership.

Changeable Conditional Survival Rates and Associated Prognosticators in Patients with Metastatic Renal Cell Carcinoma Receiving First Line Targeted Therapy

In this study we evaluated conditional survival probabilities in patients with metastatic renal cell carcinoma who underwent first line tyrosine kinaseinhibitor therapy. We also identified predictors of conditional survival with time. We retrospectively reviewed clinical data on 1,659 individuals with metastatic renal cell carcinoma in the Korean Renal Cancer Study Group database, of whom the records of 1,131 were finally analyzed. The primary end point was conditional overall survival. Kaplan-Meier survival analysis was used to calculate conditional overall survival probabilities using the formula, conditional survival (α│β) = S(α + β)/S(β), indicating the likelihood of additional α years survivorship in person who has already survived for β years after initial therapy. S(χ) represents the actual survival rate. Multivariate Cox regression model was used to identify predictors of conditional survival with time. Six, 12, 18, 24 and 36-month conditional overall survival gradually increased in patients at all additional survival times after initial treatment compared to patient baseline survival estimations. While the actual overall survival rate decreased with time, the 36-month conditional overall survival rate was calculated as 7.3% higher in patients who had already survived 36 months compared to baseline estimations at the time of initial tyrosine kinase inhibitor treatment. Furthermore, predictors of conditional overall survival changed with time. Only previous metastasectomy remained a key prognosticator of conditional overall survival until 36 months of survival following initial tyrosine kinase inhibitor treatment. Conditional survival improved with time after initial tyrosine kinase inhibitor treatment in patients with metastatic renal cell carcinoma. Our study offers valuable information for practical survival estimations and relevant prognosticators in patients with metastatic renal cell carcinoma who receive first line tyrosine kinase inhibitor.

Changeable prognosis and associated prognostic factors for conditional survival estimates in metastatic renal cell carcinoma patients receiving the first-line targeted therapy.

587 Background: Conditional survival (CS) indicates the probability that patient would survive additional periods, given that the patients has previous survivorship after diagnosis or initial treatment. Here, we aim to evaluate the CS probabilities in mRCC patients who underwent targeted therapy with tyrosine kinase inhibitors (TKI) and to identify the significant prognostic factors of the CS over time. Methods: A total of 1,498 mRCC patients receiving 1st line TKI was finally analyzed from Korean multicenter database of mRCC. Kaplan-Meier survival estimates was used to calculate overall and cancer-specific CS rates by using following formula: CS(α│β) = S(α+β)/S(β), where CS(α│β) indicates the likelihood of additional α years survivorship in the person who has already survived for β years after initial diagnosis or treatment, and S(χ) is the actual survival rate. The Cox regression analysis was used to determine the predictors of CS depended on clinicopathological features. Results: We observed that 1, 2, 3, 4, and 5-year conditional cancer-specific survival (CSS) gradually increased as patients who have all additional survivorships after initial treatment, compared to those with baseline survival estimation. Also, 1, 2, 3, 4, and 5-year conditional OS rates also increased after additional 1, 2, 3, 4, and 5 year survivorships following first-line TKI treatment. Furthermore, we found that key predictive factors of OS and CSS were changed over time in multivariate analysis. While several variables, such as BMI, histologic subtypes, pT stage, were identified as prognosticators of CSS at baseline, they were not remained as independent predictors after 1 yr survivorship. Conversely, only previous metastatectomy was determined as a key prognostic factor for conditional OS over time until 4 yr survivorship after initial TKI treatment. Conclusions: Our study offers valuable information for practical survival estimation and relevant predictive factors for patients with mRCC receiving targeted therapy.

PD-L1 expression in lung adenocarcinoma harboring EGFR mutations or ALK rearrangements

ObjectivesExpression of programmed cell death–ligand 1 (PD-L1) has been associated with clinical outcome of programmed cell death–1 (PD-1) pathway blockade in non–small cell lung cancer (NSCLC). The PD-L1 IHC 22C3 pharmDx assay, the only companion diagnostic for pembrolizumab therapy, has revealed that ∼30% of all NSCLCs express PD-L1 at a high level. The frequency of high PD-L1 expression in NSCLCs with known driver oncogenes has remained unclear, however. Materials and methodsWe retrospectively evaluated PD-L1 expression with the 22C3 assay in tumor tissue of 80 lung adenocarcinoma patients including 71 with EGFR mutations and 9 with ALK rearrangements, all of whom were treated with corresponding tyrosine kinase inhibitors (TKIs). ResultsOf the 80 tumors analyzed, 26 (32.5%) had a PD-L1 tumor proportion score (TPS) of 1%–49% and 9 (11.3%) had a PD-L1 TPS of ≥50%; 35 (43.8%) thus had a PD-L1 TPS of ≥1%. Of the 71 tumors with EGFR mutations, 23 (32.4%) had a PD-L1 TPS of 1%–49% and 7 (9.9%) had a PD-L1 TPS of ≥50%. A PD-L1 TPS of ≥1% was not associated with any clinical characteristic examined. Progression-free survival on initial TKI treatment was significantly poorer for patients with a PD-L1 TPS of ≥1% than for those with a PD-L1 TPS of <1% (p = .016). ConclusionsA subset of patients with EGFR mutations or ALK rearrangements had a PD-L1 TPS of ≥50%. Prospective studies are thus warranted to examine the efficacy of PD-1/PD-L1 inhibitors in such patients.

Comparing Gefitinib and Erlotinib With Regard To Brain Metastases Recurrence in EGFR-Mutant Non-Small Cell Lung Cancer Patients

Brain metastases of lung cancer are associated with a poor prognosis. Little research has been conducted to directly compare erlotinib with gefitinib regarding the frequency of central nerve system recurrence. This is the first study to directly compare erlotinib with gefitinib in terms of brain metastases recurrence rates in patients with EGFR-mutant NSCLC who had no brain metastasis at the time of starting TKI treatment. This was a single-center retrospective study. Advanced or recurrent non-small cell lung cancer patients with no brain metastases at the time of starting initial tyrosine kinase inhibitor treatment who received either gefitinib or erlotinib monotherapy were selected. The primary endpoint was the incidence of brain metastases, and secondary endpoints included the objective response rate, progression-free survival, overall survival, and Post-Progression Survival in subgroups based on tyrosine kinase inhibitor treatment and the occurrence of brain metastases. There were 119 patients in the gefitinib group and 13 patients in the erlotinib group. Brain metastases at disease progression were observed in 16 patients in the gefitinib group, and in no patients in the erlotinib group (13.5% vs. 0%, p=0.37). The median overall survival was 29.2 months in the gefitinib group and was not reached in the erlotinib group (p=0.14). The median PPS was 15.5 months in the gefitinib group and 23.7 months in the erlotinib group (p=0.11). Based on the occurrence of brain metastases, Post-Progression Survival was significantly longer in the no brain metastases group (8.0 months vs. 17.9 months, p=0.01). These data showed the possibility of a lower central-nerve-system recurrence rate with erlotinib compared with gefitinib. Post-Progression Survival in patients with brain metastases was significantly shorter than that of patients without brain metastases.

Severe Adverse Events By First Line Tyrosine Kinase Inhibitors Decrease Survival Rate in Patients with Newly Diagnosed Chronic Phase Chronic Myeloid Leukemia

Background: Chronic phase chronic myeloid leukemia (CML-CP) has become a manageable disease for most patients treated with tyrosine kinase inhibitors (TKIs). However, all TKIs have broad spectrum of toxic effects, and have to be managed by cessation, reduction and supportive care. The objective of this study is to analyze the adverse events (AEs) with different TKIs used as initial therapy for CML and their impact on outcome.Methods: We retrospectively evaluated a total of 494 patients with CML who received at least one TKI, imatinib, dasatinib, nilotinib and bosutinib in a practice setting between 2004 and 2014 at multicenter participating in the Hokkaido hematology study group.Results: Of the 494 patients (315 males and 179 females), with a median age of 59.5 years (range 2-93), imatinib, dasatinib or nilotinib were prescribed as the first line TKI in 283 (62.3%), 109 (24%) and 102 (22.5%) patients, respectively. Disease status at primary diagnosis was composed of chronic phase (450), accelerated phase (21) and blastic phase (23). With a median follow-up of 4.7 years in patients with CML-CP, the 5-year overall survival (OS), event-free survival (EFS) were 94.5% and 92.3%, respectively. The patients with complication or organ dysfunction (61/450, 13.6%) and age >60 (227/450, 50.4%) at diagnosis had significantly inferior OS (p= 0.0089 and p= 0.0012). The patients achieved higher rates of major molecular response (MMR) at 6 and 12 months after initial treatment with dasatinib, nilotinib vs imatinib (41.5%, 42.6% vs 12.5% and 54.3%, 54.5% vs 41.5%, p<.0001 and p<.0001), but final MMR rates were similar in dasatinib, nilotinib vs imatinib (70.2%, 70.3% vs 63.9%, p=0.179). Moreover, there were no significant differences in EFS and OS for specific TKIs (p= 0.345 and p= 0.458). Of the 450 patients with CML-CP, 312 treatment modifications after the first line TKI treatment were carried out: 144 (46.2%) TKI changes or definitive discontinuations, 60 (19.2%) dose reductions, 36 (11.5%) temporary discontinuations and 72 (23.3%) dose reductions after temporary discontinuation. The main reasons for the 312 treatment modifications were 254 AEs (81.4%) and 41 failure or progression (13.1%). After initial TKI treatment, 272 (60.4%), 118 (26.2%), 37 (8.2%) and 23 (5.1%) patients had no, 1, 2 and 3 TKI changes, respectively. However, the number of TKI changes was not related to OS and EFS (p= 0.574 and p= 0.267). In the first line TKI treatment, grade I-II and III-IV AEs occurred in 185 (41.1%) and 123 (27.3%) patients. AEs resulting in treatment modifications occurred in 142 (55.5%) patients for imatinib, 53 (53.5%) for nilotinib and 59 (62.1%) for dasatinib. Grade III-IV AEs in the first line TKI treatment was significantly correlated to inferior OS and EFS as compared with grade 0-II AEs (p= 0.00612 and p= 0.0014). Multivariate analyses confirmed the fact that grade III-IV AEs significantly predicted for inferior EFS and OS, HR=3.311, 95% CI 1.34-8.175 (p= 0.0094) and HR=3.096, 95% CI 1.4560-6.587 (p= 0.0033), respectively.Conclusions: Although long-term outcomes were similar in each TKI regardless of the first line TKI selection, severe AEs in the first line TKI treatment decreased survival rate of the patients with CML-CP. We need the personalized or some specialized treatment for elderly patients or patients with frailty. Early change of TKIs is recommended, when encountered with severe AEs of specific TKIs. DisclosuresNo relevant conflicts of interest to declare.

Gallic acid inhibition of Src-Stat3 signaling overcomes acquired resistance to EGF receptor tyrosine kinase inhibitors in advanced non-small cell lung cancer.

Tyrosine kinase inhibitors (TKIs) targeting epidermal growth factor receptor (EGFR) have clinically benefited to lung cancer patients harboring a subset of activating EGFR mutations. However, even with the remarkable therapeutic response at the initial TKI treatment, most lung cancer patients eventually have relapsed aggressive tumors due to acquired resistance to the TKIs. Here, we report that 3, 4, 5-trihydroxybenzoic acid or gallic acid (GA), a natural polyphenolic compound, shows anti-tumorigenic effects in TKI-resistant non-small cell lung cancer (NSCLC). Using both in vitro growth assay and in vivo xenograft animal model, we demonstrated tumor suppressive effect of GA was more selective for the TKI-resistant cancer compared to the TKI-sensitive one. Mechanistically, GA treatment inhibited Src-Stat3-mediated signaling and decreased the expression of Stat3-regulated tumor promoting genes, subsequently inducing apoptosis and cell cycle arrest in the TKI-resistant lung cancer but not in the TKI-sensitive one. Consistent with the in vitro results, in vivo xenograft experiments showed the TKI-resistant tumor-selective growth inhibition and suppression of Src-Stat3-dependent signaling in the GA-treated tumors isolated from the xenograft model. This finding identified an importance of Src-Stat3 signaling cascade in GA-mediated tumor-suppression activity and, more importantly, provides a novel therapeutic insight of GA for advanced TKI-resistant lung cancer.

Intrinsic resistance to EGFR tyrosine kinase inhibitors in advanced non-small-cell lung cancer with activating EGFR mutations.

Identifying activating EGFR mutations is a useful predictive strategy that helps select a population of advanced non-small-cell lung cancer (NSCLC) patients for treatment with EGFR tyrosine kinase inhibitors (TKIs). Patients with sensitizing EGFR mutations (predominantly an in-frame deletion in exon 19 and an L858R substitution) are highly responsive to first-generation EGFR TKIs, such as gefitinib and erlotinib, and show improved progression-free survival without serious side effects. However, all patients with activating EGFR mutations who are initially responsive to EGFR TKIs eventually develop acquired resistance after a median progression-free survival of 10–16 months, followed by disease progression. Moreover, ~20%–30% of NSCLC patients have no objective tumor regression on initial EGFR TKI treatment, although they harbor an activating EGFR mutation. These patients represent an NSCLC subgroup that is defined as having intrinsic or primary resistance to EGFR TKIs. Different mechanisms of acquired EGFR TKI resistance have been identified, and several novel compounds have been developed to reverse acquired resistance, but little is known about EGFR TKI intrinsic resistance. In this review, we summarize the latest findings involving mechanisms of intrinsic resistance to EGFR TKIs in advanced NSCLC with activating EGFR mutations and present possible therapeutic strategies to overcome this resistance.

Abstract 337: Mechanism of TKI resistance and role of epithelial mesenchymal transition in NSCLC

Abstract Current EGFR/c-Met tyrosine kinase inhibitor (TKI) combination therapies are shown to be susceptible to acquired resistance in the majority of NSCLC patients. To understand how cells develop EGFR/c-Met TKI resistance, we used three model NSCLC cell lines: H2170, H3255 and H1975. H2170 cell line express high levels of EGFR and c-Met and are EGFR wild-type. The H3255 cell line is positive for an EGFR TKD mutation, L858R, and is sensitive to initial TKI treatment. The H1975 cell line is positive for two EGFR TKD mutations, T790M and L858R, which confer resistance to erlotinib. Previous studies in our lab have shown that activation of alternative signaling pathways lead to the development of TKI resistance. In the wild type TKI resistant cells, H2170 erlotinib resistant (ER) and H2170 SU11274 resistant(SR), we observed activation of Wnt and mTOR pathway along with increased accumulation of β-catenin in the nucleus. However, in H1975 cells with mutated EGFR (L858R and T790M), we observed activation of only mTOR pathway. β-catenin is associated with Epithelial-Mesenchymal Transition (EMT), during which cells lose tight junction proteins such E-Cadherin and gain expression of transcriptional proteins such as β-catenin and ZEB1, which may lead to aberrant activation of Wnt signaling pathway and increased motility and invasion. Activation of mTOR pathway leads to increased expression of p70S6K and 4E-BP1 which are key translational regulators. We found increased accumulation of active β-catenin in the nucleus by 1.9-2.5 folds and 2.9-3.1 folds in H2170 ER and SR cells, respectively, compared to H2170 parental cells. In H2170 ER cells we observed modulations in key EMT-related proteins, N-Cadherin (2-3.3 fold) and Claudin-1 (2.5-14 fold) were upregulated and Snail was downregulated 1.7-2.5 fold in the presence and absence of erlotinib and EGF, when compared to H2170 parental cells. Similarly in H2170 SR cells we observed upregulation of N-Cadherin (1.3-2.3 fold) and Zeb-1 (1.2-1.4 fold) and downregulation of ZO-1 (1.4-1.9 fold) and E-Cadherin (1.5-2.0 fold) in the presence and absence of HGF and SU11274 when compared to H2170 parental cells. Morphological changes indicative of EMT were detected using immunostaining with Vimentin and E-Cadherin antibodies, which displayed increased Vimentin filaments (2-fold) and loss of E-Cadherin (5-10 fold) in H2170 ER cells when compared to H2170 parental cells. In H1975 cells we observed that proteins related to mTOR signaling pathway such as p-mTOR, p-GSK3-β, p-4EBP1 and p-p70S6K were upregulated 2.5 fold, 4-5 fold, 2.2-2.4 fold, and 4.4-10.4 fold, respectively, when compared to H3255 cells in the presence of erlotinib. Based on these results, we treated H1975 cells with combination of EGFR and mTOR inhibitors. We observed that 1 μM everolimus with 2.5 μM erlotinib synergistically inhibited cell growth by 53%. These studies may provide clinicians with novel targets for improving treatment options for future NSCLC patients. Citation Format: Ichwaku Rastogi, Gregory M. Botting, Andrew Webb, Brian L. Webb, Marie C. Nlend, Neelu Puri. Mechanism of TKI resistance and role of epithelial mesenchymal transition in NSCLC. [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 337. doi:10.1158/1538-7445.AM2015-337

Chronic Myeloid Leukemia (CML) Patients With Atypical e1a2 P190 BCR-ABL Translocation Show a Poor Response To Therapy With Tyrosine Kinase Inhibitors (TKI)

IntroductionP210 BCR-ABL translocation resulting from rearrangements within the major breakpoint cluster region (M-BCR), either e13a2 or e14a2, is the molecular hallmark of chronic myeloid leukemia (CML). However, some CML patients may harbor atypical BCR-ABL rearrangements such e1a2 P190 BCR-ABL which involves the minor breakpoint cluster region (m-BCR). Response to therapy with tyrosine kinase inhibitors (TKI) and outcome of such atypical patients is not well defined. ObjectiveTo evaluate response to TKI therapy of CML patients with the atypical e1a2 P190 BCR-ABL translocation. Patients and MethodsSince 2009, 4 patients with CML in chronic phase and with atypical e1a2 P190 BCR-ABL rearrangement have been recruited in various institutions belonging to the Hematological Molecular Biology Group (GBMH) of the Spanish Society of Hematology (SEHH). Patient characteristics, treatments administered and response to therapy for the 4 patients is shown in Table 1. BCR-ABL transcripts were revealed at diagnosis by quantitative PCR followed by conventional agarose electrophoresis of PCR products. Molecular follow-up of BCR-ABL transcripts throughout treatment was performed by quantitative PCR following the guidelines of the European Leukemia Net. ResultsOne patient received treatment (HU and INF+araC) prior to TKI (Pat. 1; Table 1). All 4 patients received Imatinib as initial TKI treatment. Two of the patients treated with Imatinib (Pat. 1,2) obtained a complete molecular response (CMR) and the other 2 (Pat. 3,4) only achieved a complete hematological response (CHR) as best response (Table 1). All patients had to switch to a second generation TKI (3 Nilotinib and 1 Dasatinib) due to intolerance to Imatinib (n=1; Pat. 1) or resistance (n=3; Pat. 2-4). The patient who received Dasatinib as second line TKI (Pat. 3) only achieved a partial hematologic response (PHR) and was changed to Nilotinib as third line TKI, achieving CHR after which the patient entered in blast crisis and died 36 months after diagnosis (Table 1). Overall, only 1 (Pat. 1) out of the 4 patients included in the present study achieved a sustained molecular response with Imatinib. At last follow-up, among the 4 patients included in the study, all 4 had needed a change of TKI, 1 had died due to disease progression (Pat. 3) and only 2 of them retained a molecular response (Pat. 1,2). [Display omitted] ConclusionCML patients harboring atypical e1a2 P190 BCR-ABL transcripts show a poor response and short-lived responses to TKI therapy and therefore should be identified as high-risk patients at diagnosis. These patients must be closely monitored during therapy with TKI and should be treated upfront with a second generation TKI or even be considered for allogeneic SCT in the early phase of the disease.Paper presented on behalf of the Hematological Molecular Biology Group (GBMH) of the Spanish Society of Hematology (SEHH). AJ-V and IB contributed equally to this work. Disclosures:No relevant conflicts of interest to declare.

Abstract 4455: Studies of early adaptive resistance in mutant-EGFR and EML4-ALK addicted non-small cell lung cancer in escape against small molecule inhibitors.

Abstract Lung cancer is the second most common malignancy in the United States with the highest cancer-mortality rate. Molecular targeted therapy in oncogene addicted non-small cell lung cancer (NSCLC) has gain landmark proof-of-principle success in clinical utility in recent years. Prime examples are EGFR targeted therapy against mutated EGFR tumors using tyrosine kinase inhibitors (TKIs) such as erlotinib/gefitinib, and also ALK targeted therapy against EML4-ALK tumors using ALK inhibitor crizotinib. Superior response rates and progression free survival outcomes were observed with the use of targeted therapeutics even in first line setting. Nonetheless, targeted therapeutics against mutant-EGFR and EML4-ALK tumors invariably develop an acquired tumor resistance to the TKIs. Mutational resistant mechanism has been well-established. Alternative signal pathway activation such as MET/HGF in both EGFR and ALK TKI resistance, or HER family signaling activation in EML4-ALK resistance have also been reported. We have recently begun studies focusing on the non-mutational mechanisms of tumor resistance under early time window of TKI treatment. Using HCC827 and PC9 cells as mutant EGFR addiction model, as well as H3122 and H2228 NSCLC cells as EML4-ALK addicted model, we have uncovered a novel early adaptive TKI resistance that can be evident as early as 7-14 days under initial TKI treatment. The early adaptive tumor cells displayed remarkable tumor resistance against the TKIs with 100-fold higher IC50. In mutant-EGFR against erlotinib, there was an upregulated mitochondrial antiapoptotic/prosurvival BCL-2/BCL-xL signaling dependence that is MET-independent. The early resistant cells were adaptive, highly reversible and adopted a quiescent state during TKI-induced resistance. On the other hand, our studies of early TKI resistance in EML4-ALK fusion cells revealed that while the adaptive resistance to TAE684 was also reversible, it appears to be not dependent on BCL-2/BCL-xL upregulation. We found that in both targeted TKI early resistance, the tumor survivor cells exhibited epithelial-mesenchymal transition (EMT) markers changes with decreased E-cadherin expression and increased vimentin expression. Our studies also provided in vitro and in vivo evidence that these early adaptive TKI resistant tumor cells can be targetable for prevention or eradication of tumor resistance emergence, such as utilizing BCL-2/BCL-xL pathway inhibitors, such as ABT-737, in combination with EGFR TKI in mutant-EGFR addicted NSCLC. Further preclinical model studies will focus on investigating the molecular and genomic changes and gene network regulation in the early adaptive resistant tumor cells, to enable a new paradigm of novel therapeutic targets discovery to overcome early tumor resistance emergence and improve long term outcome of targeted therapy in lung cancer. Citation Format: Lihong Yin, Ivy Shi, Wei Zhang, Rakesh Bagai, Yan Feng, Patrick C. Ma. Studies of early adaptive resistance in mutant-EGFR and EML4-ALK addicted non-small cell lung cancer in escape against small molecule inhibitors. [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 4455. doi:10.1158/1538-7445.AM2013-4455

Efficacy of Sunitinib and Sorafenib in Metastatic Papillary and Chromophobe Renal Cell Carcinoma

Sunitinib and sorafenib are novel tyrosine kinase inhibitors (TKIs) that have shown significant clinical activity in metastatic clear cell renal cell carcinoma (RCC). The activity of sunitinib and sorafenib in non-clear cell histologies has not been evaluated. Clinical features at study entry and treatment outcomes were evaluated in patients with metastatic papillary RCC (PRCC) and chromophobe RCC (ChRCC) who received either sunitinib or sorafenib as their initial TKI treatment in five US and French institutions. Response rate and survival were documented. Fisher's exact test was used for categoric variables, and the Kaplan-Meier method was used to estimate survival. Fifty-three patients were included. The number of patients with papillary and chromophobe histologies was 41 (77%) and 12 (23%), respectively. Response rate, progression-free survival (PFS) time, and overall survival time for the entire cohort were 10%, 8.6 months, and 19.6 months, respectively. Three (25%) of 12 ChRCC patients achieved a response (two patients treated with sorafenib and one treated with sunitinib), and PFS was 10.6 months. Two (4.8%) of 41 PRCC patients achieved a response (both patients were treated with sunitinib). PFS for the whole cohort was 7.6 months. Sunitinib-treated PRCC patients had a PFS of 11.9 months compared with 5.1 months for sorafenib-treated patients (P < .001). Patients with PRCC and ChRCC may have prolonged PFS from sunitinib and sorafenib, although clinical responses remain overall low in PRCC. Additional prospective trials with these agents in non-clear cell RCC will further clarify their use in the future.

Treatment outcome for metastatic papillary and chromophobe renal cell carcinoma (RCC) patients treated with tyrosine-kinase inhibitors (TKIs) sunitinib and sorafenib

5037 Background: Sunitinib (SUNI) and sorafenib (SORAF) are novel TKIs that have shown significant clinical activity in metastatic clear-cell RCC. Papillary (PAP) and chromophobe (CHRM) histologies represent the majority non-clear-cell RCC. The activity of SUNI and SORAF in non-clear cell histologies has not been evaluated. Methods: Clinical features at study entry and treatment outcomes were evaluated in all patients (pts) with metastatic PAP and CHRM RCC who received either SUNI or SORAF as their initial TKI treatment at one of five different cancer centers in France and USA between 2002 and 2006. Descriptive statistics were used to evaluate the collected data. Overall Response rate (ORR) was investigator-assessed per RECIST criteria. Fisher’s exact test was used for categorical variables and the Kaplan-Meier method was used to estimate survival (Overall Survival (OS) and progression-free survival (PFS)). Results: Median age for the 53 patients was 59 years and 64% were male. The number of patients with PAP and CHRM histologies were 41 (77%) and 12 (23%), respectively. Nephrectomy was performed in 87% of patients and 33/53 (62%) of pts were previously treated (26/33, 79%, with cytokines). ORR, PFS and OS for the entire cohort were 10%, 8.9 months (m) and 12.2 m, respectively. Twenty (38%) and 33 (62%) pts were treated with SUNI and SORAF, respectively. 3/12 (25%) of CHRM pts had an ORR vs. 2/41(4.8%) with PAP histology (P=0.07). PFS for CHRM pts was 9.3 m compared to 6.6 m for PAP pts (p=0.07). OS was not different across histologies and type of TKI received. SUNI treated pts had an ORR of 15% and PFS of 11.9 m compared to 6% (p=0.3) and 5.5 m for SORAF pts (p=0.002), respectively. Other factors found to be associated with shorter PFS include ECOG PS &gt;0 (p=0.03) and hemoglobin&lt; normal (p=0.02). Conclusions: TKI may have activity in metastatic CHRM RCC, similar to what is seen in clear-cell histology. Minimal activity however is noted in PAP RCC, justifying continued investigations of novel agents in this histology. No significant financial relationships to disclose.