Generation Tyrosine Kinase Inhibitors Research Articles

CML-266: Second Generation Tyrosine Kinase Inhibitors in First Line Can Reduce the Time to Treatment-Free Remission in Chronic Myeloid Leukemia Patients

Introduction Duration of treatment with tyrosine kinase inhibitors (TKI) is an important favorable prognostic factor for treatment-free remission (TFR) and deep molecular response (DMR) in patients (pts) with chronic myeloid leukemia (CML). Aim To analyze the impact of first-line treatment duration with imatinib and 2G TKI on molecular relapse-free survival (MRFS) in CML pts with sustained DMR. Patients and methods In total, 174 CML pts in chronic phase with ≥3 years treatment duration and sustained DMR (MR4-MR5, BCR-ABL IS 0.1%). Median (Me) age of pts was 43 (range 21-86) years; 39% were males. Me TKI treatment duration was 86 months (IQR 57-125 mo), Me DMR duration was 45 (IQR 29-66 mo). Imatinib, 2G TKI in first-line and 2G TKI in second-line were discontinued in 116 (66.7%), 15(8.6%) (11 nilotinib, 3 dasatinib, 1 bosutinib) and 43 (24.7%) (34 nilotinib, 9 dasatinib) pts respectively. Results Me follow-up time after treatment cessation was 33 months (range 1-133). MRFS at 6, 12, 24 and 36 months was 62% (CI: 55-70%), 53% (CI: 45-60%), 50% (CI: 42-57%) and 48% (CI: 40-56%) respectively. Treatment duration and MR4.5 vs MR4 were significant for MRFS both in univariate (p=0.009 and p=0.015) and multivariate analysis (p=0.017 and p=0.037). No difference in 36 months MRFS was observed for imatinib (47% (CI: 42-60%)), first-line 2G TKI (59% (CI: 33-84%) p=0.58) and second-line 2G TKI (47% (CI: 32-63%) p=0.97) groups. However, significantly shorter treatment duration was observed in first-line 2G TKI group (Me=44 mo (IQR 40-52 mo)) vs imatinib (Me=93 mo (IQR 69-127 mo)), p Conclusion The 2G TKI as a first-line seem to be an effective option to reduce the treatment duration before TFR in CML pts although MRFS rate was not significantly improved in our study.

ALL-159: A Retrospective Real-Life Report on Newly Diagnosed Adult Ph+ Acute Lymphoblastic Leukemia (Ph+ ALL) Patients Treated in Italy - The CAMPUS-ALL Experience

Background The unfavorable prognosis of Ph+ ALL has improved following the introduction of tyrosine kinase inhibitors (TKIs). While the GIMEMA trials are based on a chemo-free induction strategy, information is lacking on long-term follow-up of enrolled patients, and of patients treated outside of clinical trials. Aims and methods To evaluate the real-life experience on newly diagnosed adult Ph+ ALL patients treated with TKIs in Italy, we retrospectively collected data from 7 centers from 1/2000 to 12/2017 within the Campus ALL program. Results 158 patients (mean age: 51.8 years) were included; 69 were treated within GIMEMA trials. Induction therapy was: TKI+steroids (n=91), TKI+chemotherapy (n=39), and chemotherapy alone (n=28). A complete hematologic remission (CHR) was achieved in 99%, 100%, and 87% of patients, respectively. Minimal residual disease (MRD) at 3 months was available in 92 patients (52 outside of a clinical trial): 75% had MRD levels > 0.01 and 25% ≤0.01. Fifty-five patients received TKIs as consolidation and 77 chemotherapy. Seventy patients underwent an allogeneic and 5 an autologous transplant, 41 in first CHR. Of the allografted patients, 19/75 (25%) relapsed; 32 received TKIs post-transplant. Among the 77 non-transplanted cases, 35 (45%) relapsed; the majority (71%) continued TKI treatment: among those still alive, 3 stopped it. With a median follow-up of 61.8 months, overall survival (OS) and disease-free survival (DFS) at 5 years are 50% and 59% (median not reached). Prognostic factors for OS were transplantation (HR 0.44, p 65 yo; HR 2.14, p 40% of cases; nevertheless, the lack of its impact suggests that in MRD+ cases, salvage with novel treatments (i.e., newer generation TKIs and immunotherapy) can improve the outcome of Ph+ ALL. Conclusions We provide an overview of the long-term outcome of an unselected cohort of patients treated between 2000 and 2017, which documents the improved prognosis of Ph+ ALL also in the real-life setting. Further cases are being collected.

LBA60 ZENITH20, a multinational, multi-cohort phase II study of poziotinib in NSCLC patients with EGFR or HER2 exon 20 insertion mutations

Treatment of non-small cell lung cancer (NSCLC) with EGFR or HER2 exon 20 mutations is a serious unmet medical need. We are evaluating the efficacy and safety of poziotinib, a potent EGFR and HER2 exon 20 tyrosine kinase inhibitor (TKI), in a large, prospective multi-cohort study (N=603). Here, we report results from a cohort of previously treated patients with advanced NSCLC exon 20 insertion mutations (ZENITH20-2 N=90). Patients enrolled in ZENITH20-2 had HER2 exon 20 insertion mutations per a CLIA certified (or equivalent) sequencing test. Poziotinib (16 mg) was administered orally QD, allowing dose interruptions/reductions for toxicity if needed. The primary endpoint was objective response rate (ORR), evaluated centrally by an independent image review committee using RECIST 1.1 with a 95% CI pre-specified lower bound of 17%. Secondary endpoints included disease control rate, duration of response, progression-free survival, and safety. In ZENITH20-2, 90 patients were enrolled with a median age of 60 years; 64% females, 66% non-smokers, 78% Caucasians, and 16% had concurrent clinically stable brain metastases at entry. Median number of prior therapies was 2 (range: 1-6), with 98% of patients having prior chemo/platinum-based therapy; 67% immunotherapy, including checkpoint inhibitors; and 28% HER2 therapy. The most common treatment-related Grade ≥3 AEs were rash (30%), diarrhea (26%), and mucosal inflammation (14%). ORR in 74 evaluable patients was 35.1% (95% CI: 24.4 – 47.1%) and 27.8% (95% CI: 18.9 – 38.2%) in all 90 patients (As-Treated Population). The 95% CI lower bound exceeded the protocol-specified threshold of 17%. Median DoR was 5.1 months (range: 1-12.3+ months) with 3 patients continuing on treatment. DCR was 70% and median PFS was 5.5 months (range: 0.03-13.1+ months). Responses were observed in most subgroups. Specifically, ORR was 38.7% in 31 patients with 3+ lines of therapy and 28.6% in 14 patients with CNS metastasis. ZENITH20-2 met its ORR primary efficacy endpoint with durable responses and presented a manageable safety profile, typical of 2nd generation TKIs. Additional cohorts are enrolling to explore alternative dose levels and BID dosing.

PLCγ1‑dependent invasion and migration of cells expressing NSCLC‑associated EGFR mutants.

The increased tyrosine kinase activity of non‑small cell lung cancer (NSCLC)‑associated epidermal growth factor receptor (EGFR) mutants results in deregulated pathways that contribute to malignant cell survival, tumor progression and metastasis. Previous studies investigating lung cancer‑associated EGFR have focused on the prognostic implications of receptor kinase mutations in patients with NSCLC; however, the role of EGFR mutations in tumor cell invasion and migration remains undetermined. The present study was designed to investigate the role of NSCLC‑associated mutant EGFR‑driven signaling pathways in cell proliferation and invasion. Non‑endogenous EGFR‑expressing 293cells stably expressing EGFR mutants that are sensitive or resistant to Food and Drug Administration(FDA)‑approved EGFR‑targeted tyrosine kinase inhibitors(TKIs) were used in the present study. The experiments demonstrated an increased phosphorylation of phospholipase (PLC)γ1, c‑Cbl, signal transducer and activator of transcription(Stat), extracellular regulated kinase (Erk)1/2, Akt, Shc and Gab1 proteins in cells expressing a mutant form, rather than the wild‑type receptor. As PLCγ1 is a known regulator of metastatic development, mutant receptor‑mediated PLCγ1 activation was further evaluated. To examine the effects of EGFR and PLCγ1 phosphorylation, the metastatic potential of cells expressing mutants was investigated using wound healing, Transwell cell migration and invasion assays. The inhibition of receptor phosphorylation with the 1st, 2nd and 3rdgeneration TKIs, gefitinib, afatinib, osimertinib, respectively, reduced PLCγ1 phosphorylation, and reduced the invasive and migratory potential of 293cells, confirming PLCγ1 as one of the probable downstream effectors of mutant EGFR signaling. However, the PLC inhibitor, U73122, inhibited cell migration and invasion without affecting EGFR signaling and PLCγ1 phosphorylation. Notably, U73122 reduced Akt and Erk1/2 phosphorylation within 25min of its application; however, 100%cell viability was recorded even after 48h. Upon further investigation, proliferative signaling pathways remained active at 48h, in accordance with cell viability. Therefore, the present study concludes that mutant receptor‑mediated PLCγ1 activation may play a significant role in the migration and invasion of NSCLC tumors; however, its regulatory role in tumor cell proliferation warrants further investigation and validation in lung tumor cell lines harboring EGFR mutations.

Abstract 6304: Decrypting EGFR signaling with BRET biosensors: A novel approach to study RTK mutations and the effects of inhibitors

Abstract Receptor tyrosine kinases (RTKs) comprise nodes at the center of complex signaling networks regulating various aspects of cell growth, differentiation and survival. Dysregulated RTK activity can alter many cellular processes, often culminating in cancer. Consequently, RTKs are prime targets for new anti-cancer agents. Yet, the efficacy of these drugs is limited by the development of drug-induced adverse events and acquired resistance. Discovery of novel therapeutics devoid of such limitations requires a deeper understanding of often overlooked determinants of therapeutic efficacy, including kinetics, subcellular localization, signaling bias and drug target mutations. In this study, we present a live-cell BRET-based biosensor platform applicable to studying such key elements, which allows for real-time spatiotemporal monitoring of RTK signaling across more than 10 effector proteins/pathways. Using EGFR and two of its ligands (EGF and Epiregulin) as a model system, we used our platform to highlight spatiotemporal signaling bias. Indeed, Epiregulin-induced engagement of effector protein Grb2 was more efficacious (25%) and displayed faster kinetics relative to that observed with EGF. Interestingly, EGF, but not Epiregulin, promoted a gradual increase in Grb2 levels at early endosomes. These data highlight opportunities for the identification of biased ligands displaying improved therapeutic efficacy. The impact of various glioblastoma-related EGFR mutations on receptor signaling were also profiled. The EGFR(vI) mutant showed constitutive activity on the PLCG1 effector pathway while the EGFR(vV) mutant was uniquely constitutive on SHIP1 and SHIP2 pathways. Further, EGFR(vIII) was devoid of constitutive activity on some effector proteins (PLCG1, Grb2) and highly constitutive on others (PI3K, SHIP1/2). The G598V mutant showed constitutive activity on all pathways except Grb2. This data shows how oncogenic mutations can rewire an RTK's signaling network. Identification and targeting of common signaling nodes exploited by various mutants could enhance drug efficacy and minimize mutation-related drug resistance. Finally, RTK biosensors were used to screen for tyrosine kinase inhibitor (TKI) activity on EGFR kinase domain mutants found in NSCLC (T790M and C797S). 1st generation TKI Gefitinib and 4th generation TKI Osimertinib reversed EGF activation of WT EGFR. However, only Osimertinib could reverse EGF-mediated activation of EGFR(T790M) but was ineffective at inhibiting EGFR(C797S). The platform could thus serve as a tool to assess anti-cancer treatment efficacy against various RTK mutants. These data position our biosensor platform as a versatile technology to study multiple facets of RTK biology and pharmacology. Access to real-time, spatiotemporal readouts across multiple signaling pathways will enable the development of novel RTK-based anti-cancer agents. Citation Format: Florence Gross, Guilhem Dugast, Arturo D. Mancini, Stephan Schann, Xavier Leroy. Decrypting EGFR signaling with BRET biosensors: A novel approach to study RTK mutations and the effects of inhibitors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6304.

Abstract 1094: Genetic determinants of EGFR-driven lung cancer growth and therapeutic response in vivo

Abstract Oncogenic alterations in the Epidermal Growth Factor Receptor (EGFR) gene are found in ~15% of lung adenocarcinomas (LUADs). EGFR mutations predict sensitivity to EGFR tyrosine kinase inhibitors (TKIs) and these drugs are approved for the first-line treatment of patients with EGFR mutant lung cancer. Response rates to TKIs are high, however, there is variability in the duration and depth of response between patients and acquired resistance to TKIs inevitably emerges. EGFR mutant tumors harbor numerous additional co-occurring alterations in addition to the driver mutations that are likely to contribute to the malignant phenotype of these tumors and the variability in therapeutic response. TP53 is the most common tumor suppressor gene (TSG) co-mutated with EGFR, and alterations in TP53 correlate with worse outcomes upon TKI treatment. However, the functional contribution of loss of other LUAD-associated TSGs to tumor progression and drug resistance in EGFR mutant tumors remains poorly understood. To study the role of 10 putative tumor suppressor genes–that are frequently altered in human LUADs–for EGFR mutant tumors, we developed a conditional lung cancer model based on the inducible expression of EGFRL858R and deletion of Tp53 in the lungs via lentiviral delivery of Cre recombinase. We coupled this EGFRL858R;p53flox/flox mouse model with multiplexed CRISPR-Cas9-mediated genome editing and performed an in vivo screen to quantify the effects of inactivation of these 10 TSGs on tumor growth and TKI sensitivity. We found that inactivation of Apc, Rb1, and Rbm10 each strongly promoted growth while loss of Lkb1 or Setd2 reduced tumor growth. In contrast, in a KrasG12D;p53flox/flox model inactivation of Lkb1 or Setd2 were the strongest drivers of tumor growth. To establish the relevance of the functional data from mouse models for human tumors, we examined the AACR Project Genomics Evidence Neoplasia Information Exchange (GENIE) database. Consistent with the mouse data, of the 10 TSGs screened, APC, RB1 and RBM10 were the most frequently mutated in EGFR/TP53 mutant LUADs. We also tested whether inactivation of any of the 10 TSGs was associated with a reduced response to TKIs, by treating mice infected with the lentiviral pool targeting the TSGs with the 3rd generation TKI osimertinib and found that loss of Keap1 was associated with a diminished response to therapy. Collectively, our data have: i) uncovered striking specificity of TSG function in EGFR mutant LUADs, ii) discovered that inactivation of some TSGs can have diametrically opposite effects depending on the nature of the initiating oncogene and iii) established a causal link between certain tumor genotypes and differential responses to EGFR inhibition. Ongoing studies are aimed at investigating the mechanistic underpinnings of these findings. Citation Format: Giorgia Foggetti, Chuan Li, Hongchen Cai, Wen-Yang Lin, Deborah Ayeni, Katherine Hastings, Laura Andrejka, Dylan Maghini, Robert Homer, Dmitri A. Petrov, Monte M. Winslow, Katerina Politi. Genetic determinants of EGFR-driven lung cancer growth and therapeutic response in vivo [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1094.

Abstract CT081: Poziotinib activity and durability of responses in previously treated EGFR exon 20 NSCLC patients - a Phase 2 study

Abstract Introduction and Purpose of Study: Effective and approved therapy for treating non-small cell lung cancer (NSCLC) with EGFR exon 20 mutations is an unmet medical need. Poziotinib is a potent tyrosine kinase inhibitor (TKI) of EGFR and HER2 exon 20 insertion mutants. We evaluated the efficacy and safety of poziotinib in previously treated NSCLC patients with EGFR exon 20 insertion mutations (ZENITH20-1) in an independent cohort of a multi-cohort, multi-center Phase 2 study. Methods: Poziotinib (16 mg) was administered orally QD, allowing dose reductions for AEs, with follow up for 24 months. The primary endpoint was objective response rate (ORR), evaluated by central radiographic review using RECIST v1.1. The ORR endpoint was to be met if the lower bound of 95% CI>17% in the As-Treated Population. The secondary endpoints included disease control rate (DCR), duration of response (DOR), progression-free survival (PFS) and safety. Safety monitoring was conducted throughout the study. Results: A total of 115 patients with a median age of 61 years (33-83) were enrolled. Patients had received and failed prior therapy (median of 2 [1-9]) with majority receiving both chemo and immunotherapy. The median relative dose intensity was 72% (7-100%) with 65% having dose reductions. 10% of patients discontinued due to related AEs. The ORR was 14.8% (95% CI 8.9%-22.6%), and the DCR was 68.7% (95% CI 59.4%-77.0%). Seventeen patients had a confirmed partial response (PR), 5 patients had unconfirmed PR and 62 (53.9%) patients had stable disease (SD). Overall, 75 (65%) patients had tumor size reductions. The median DoR was 7.4 months (95% CI 3.7-9.7) and the median PFS was 4.2 months (95% CI 3.7-6.6). Safety profile was mechanism related and similar to other 2nd generation tyrosine kinase inhibitors with the most common treatment-related Grade ≥3 AEs (preferred term) being rash (28%), diarrhea (26%), stomatitis (9%) and paronychia (6%). The incidence of treatment-related pneumonitis, an important AE associated with TKIs, was 4%. Conclusion: Although the ORR primary endpoint was not met, poziotinib induced tumor size reduction in the majority (65%) of patients. The tumor size reduction combined with long duration of response demonstrated the clinical activity of poziotinib in treating this patient population. We are further optimizing dosing and AE management. Citation Format: Xiuning Le, Jonathan Goldman, Jeffrey Clarke, Nishan Techekmedyian, Zofia Piotrowska, David Chu, Gajanan Bhat, Francois Lebel, Mark Socinski. Poziotinib activity and durability of responses in previously treated EGFR exon 20 NSCLC patients - a Phase 2 study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT081.

Bcr-Abl Tyrosine Kinase Inhibitors in the Treatment of Pediatric CML.

The therapeutic approach to Chronic Myeloid Leukemia (CML) has changed since the advent of the tyrosine kinase inhibitor (TKI) imatinib, which was then followed by the second generation TKIs dasatinib, nilotinib, and, finally, by ponatinib, a third-generation drug. At present, these therapeutic options represent the first-line treatment for adults. Based on clinical experience, imatinb, dasatinib, and nilotinib have been approved for children even though the studies that were concerned with efficacy and safety toward pediatric patients are still awaiting more specific and high-quality data. In this scenario, it is of utmost importance to prospectively validate data extrapolated from adult studies to set a standard therapeutic management for pediatric CML by employing appropriate formulations on the basis of pediatric clinical trials, which allow a careful monitoring of TKI-induced adverse effects especially in growing children exposed to long-term therapy.

Cardiotoxicity of the BCR-ABL1 tyrosine kinase inhibitors: Emphasis on ponatinib

The advent of tyrosine kinase inhibitors (TKIs) targeted therapy revolutionized the treatment of chronic myeloid leukemia (CML) patients. However, cardiotoxicity associated with these targeted therapies puts the cancer survivors at higher risk. Ponatinib is a third-generation TKI for the treatment of CML patients having gatekeeper mutation T315I, which is resistant to the first and second generation of TKIs, namely, imatinib, nilotinib, dasatinib, and bosutinib. Multiple unbiased screening from our lab and others have identified ponatinib as most cardiotoxic FDA approved TKI among the entire FDA approved TKI family (total 50+). Indeed, ponatinib is the only treatment option for CML patients with T315I mutation. This review focusses on the cardiovascular risks and mechanism/s associated with CML TKIs with a particular focus on ponatinib cardiotoxicity. We have summarized our recent findings with transgenic zebrafish line harboring BNP luciferase activity to demonstrate the cardiotoxic potential of ponatinib. Additionally, we will review the recent discoveries reported by our and other laboratories that ponatinib primarily exerts its cardiotoxicity via an off-target effect on cardiomyocyte prosurvival signaling pathways, AKT and ERK. Finally, we will shed light on future directions for minimizing the adverse sequelae associated with CML-TKIs.

Chelidonine selectively inhibits the growth of gefitinib-resistant non-small cell lung cancer cells through the EGFR-AMPK pathway

Tyrosine kinase inhibitors (TKIs) have been widely used for the clinical treatment of patients with non-small cell lung cancer (NSCLC) harboring mutations in the EGFR. Unfortunately, due to the secondary mutation in EGFR, eventual drug-resistance is inevitable. Therefore, to overcome the resistance, new agent is urgently required. Chelidonine, extracted from the roots of Chelidonium majus, was proved to effectively suppress the growth of NSCLC cells with EGFR double mutation. Proteomics analysis indicated that mitochondrial respiratory chain was significantly inhibited by chelidonine, and inhibitor of AMPK effectively blocked the apoptosis induced by chelidonine. Molecular dynamics simulations indicated that chelidonine could directly bind to EGFR and showed a much higher binding affinity to EGFRL858R/T790M than EGFRWT, which demonstrated that chelidonine could selectively inhibit the phosphorylation of EGFR in cells with EGFR double-mutation. In vivo study revealed that chelidonine has a similar inhibitory effect like second generation TKI Afatinib. In conclusion, targeting EGFR and inhibition of mitochondrial function is a promising anti-cancer therapeutic strategy for inhibiting NSCLC with EGFR mutation and TKI resistance.

Lungful: An observational prospective study to assess the molecular epidemiology of EGFR mutations upon progression on or after first line EGFR-TKI therapy, in real-life clinical settings in Greece.

e21641 Background: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are the gold standard 1st line strategy for non-small-cell lung cancer (NSCLC) patients with activating EGFR mutations (EGFRm), associated with improved survival outcomes and quality of life compared to chemotherapy. Despite the high response rate with first- and second- generation TKIs, most patients develop resistance to treatment and progress. The acquisition of T790M mutation in exon 20 is considered the most common resistance mechanism. This study aims to investigate the molecular epidemiology of EGFR resistance mutations, focusing on T790M in EGFRm NSCLC patients treated with TKIs. Methods: The study included patients with locally advanced/metastatic EGFRm NSCLC who have progressed on or after 1st line treatment with first- or second- generation TKI. Samples either from plasma-based liquid biopsy and/or tissue re-biopsy were analysed using the Cobas EGFR Mutation Test v2. All patients signed informed consent and were enrolled between July 2017 and September 2019. Statistical analyses were performed using SAS software, Version 9.4. Results: Ninety-six eligible patients were enrolled. At the time of progression, T790M mutation was detected in 16.7%of the patients using plasma-based liquid biopsies. Among patients with negative T790M result, in plasma, tissue re-biopsy was performed in 22,7% with evaluable/valid results in 72.2% of them. T790M mutation was identified in 38.5% of re-biopsy samples. According to Cobas EGFR Mutation test results (combined plasma and tissue), T790M mutation was identified in 21.9% of the patients. Of T790M-positive patients 42.9% had previously received first and 57.1% second generation EGFR-TKI. Conclusions: Results from this study in real world clinical setting in Greece, show that EGFR-T790M acquired resistance positivity rate in plasma is lower compared to previous reports. Moreover, these data underline the challenges of implementing precision medicine using tissue re-biopsy in advanced/metastatic NSCLC. Clinical trial information: D133FR00126. [Table: see text]

Progression free survival (PFS) in Asian vs non-Asian patients (pts) with EGFR mutant non-small cell lung cancer (NSCLC) receiving osimertinib.

e21679 Background: Third generation EGFR tyrosine kinase inhibitor (TKI) osimertinib demonstrated superior PFS and OS compared to earlier generation TKIs in pts with EGFR+ NSCLC. These pts are disproportionately Asian, female, and never-smokers. Contradictory data has been reported regarding the PFS and OS to osimertinib in Asian pts as compared to 1st and 2nd generation EGFR TKI. These inconsistencies warrant further investigation. The purpose of this study is to evaluate the PFS in Asian vs non-Asian pts with EGFR+ NSCLC receiving osimertinib. Methods: We conducted a single institution IRB approved retrospective study of pts with EGFR+ NSCLC. PFS was evaluated in pts treated from 1/2013 – 12/2019. Disease and treatment characteristics were summarized using frequency distributions and Kaplan-Meier curves for comparison of subgroups. Results: Of 190 EGFR+ pts: 52 (27%) Asian, 108 (57%) Caucasian, 125 (66%) female, 172 (91%) advanced disease, 107 (56%) never-smokers. Baseline characteristics in Asian and non-Asian pts were similar in regards to de-novo stage IV disease (71% vs 65%, p = 0.80), brain metastases (42% vs 54%, p = 0.48), and differed with regards to ever-smoking (29% vs 56%, p = 0.04). Treatment: 126/172 (73%) pts with advanced disease received TKI across all lines of therapy; 92/126 received osimertinib (22 (24%) 1st line; 45 (49%) 2nd line; 18 (19%) 3rd line; 7 (8%) ≥4th line). There were insufficient number of pts who received osimertinib in the 1st line to comment on differences in PFS between Asian and non-Asian pts. In the 2nd line, 19 Asian pts and 26 non-Asian pts received osimertinib, with no observed difference in PFS (median 15.4 v 13.8 months, p = 0.20). Moreover, Asian pts who received osimertinib as second line therapy had superior PFS (median 15.4 vs 9.6 months, p < 0.01) compared to Asian pts who received earlier generation TKIs, likely due to T790M resistance. Conclusions: Among second line advanced EGFR+ NSCLC, we did not observe a difference in PFS between Asian and non-Asian pts treated with osimertinib. Median PFS in Asian pts treated with osimertinib was longer compared to those treated with 1st or 2nd generation TKIs in the 2nd line setting. Our study highlights the the role of ethnic background in response to EGFR therapies and may warrant further study.

Osimertinib in non-small cell lung cancer (NSCLC) with atypical EGFR activating mutations: A retrospective multicenter study.

9570 Background: Osimertinib (osi) is a 3rd generation EGFR tyrosine kinase inhibitor (TKI) approved for first line (1L) treatment of metastatic NSCLC harboring EGFR Exon 19 del and L858R (representing > 80% of EGFR activating mutations) or in NSCLC with EGFRT790M (the most common resistance mutation to 1st or 2nd generation TKI). However, it has not been well-studied in EGFR-mutant NSCLC harboring less common EGFR activating mutations such as G719X, L861Q, S768I, and exon 20 insertion (ins), among others. Methods: We conducted a multi-institution, retrospective study approved on institutional IRB protocols in a series of patients (pts.) with metastatic NSCLC treated with osi who harbored at least one atypical EGFR mutation, excluding those with concurrent L858R, Exon 19 del, or T790M. Kaplan-Meier analyses were generated with SPSS, v25 (IBM Corp., USA). Response was assessed by RECIST 1.1 in evaluable pts. Time on osi was employed as a surrogate endpoint for clinical benefit in this retrospective analysis. Results: Fifty-one NSCLC pts with uncommon EGFR mutations were identified among six US institutions. Pt characteristics: 72.5% women, median age 65 yo (44-83 yo), 82.3% ECOG PS 0-1, 43.1% never smoker, 100% lung adenocarcinoma, 58.8% Caucasian, 25.5% Asian, 3.9% Black, 2.0% Hispanic, and 9.8% Other. The most frequent mutations were L861Q (35.3%, N = 18), G719X (27.5%, N = 14), and Exon 20 ins (15.7%, N = 8). Osi was used in the 1L setting in 39.2% (N = 20). Median time on osi was 7.1 months (mo.) in the overall cohort (95% CI, 5.4 to 8.8 mo.) and 8.9 mo. (95% CI, 7.0 to 10.8 mo.) in pts receiving 1L osi. Patients harboring G719X (N = 4) and L861Q (N = 10) mutations had a median time on 1L osimertinib of 5.8 mo. and 19.3 mo., respectively. One patient’s tumor had an EGFR exon 19 ins and was on 1L osi with a partial response for 16.8 months. Two patients with Exon 20 ins were on 1L osi for 9.3 mo. and 8 mo., respectively. Conclusions: In this largest known clinically annotated dataset of patients with atypical EGFR-mutations treated with osi, activity was noted, though 1L clinical benefit on osi appears lower in this multicenter US cohort than in E19del or L858R. These results are comparable to the recently published prospective phase II trial ( Cho et al, 2019) conducted in Korea. Patients with L861Q and Exon 19 insertion appeared to benefit the most from osi in this time on treatment retrospective analysis. More detailed analysis of this cohort is planned and further prospective studies are warranted to determine clinical benefit of osi amongst diverse atypical EGFR-mutations.

A phase II trial of durvalumab (MEDI4736) and tremelimumab with chemotherapy in metastatic EGFR mutant non-squamous non-small cell lung cancer (NSCLC) following progression on EGFR tyrosine kinase inhibitors (TKIs) (ILLUMINATE).

TPS9631 Background: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have proven remarkably effective in the treatment of advanced EGFR mutant non-small cell lung cancer (NSCLC). However, drug resistance is inevitable and outcomes with subsequent platinum-pemetrexed chemotherapy are poor. The role of immune-checkpoint inhibitor monotherapy in EGFR mutant NSCLC remains uncertain with trials demonstrating inferior survival outcomes compared to chemotherapy. However, a recent randomised study with combination checkpoint inhibitor-chemotherapy demonstrated improved survival over chemotherapy alone in this patient population. This study aims to evaluate the efficacy and tolerability of combination dual immune-checkpoint blockade, durvalumab and tremelimumab, with platinum-pemetrexed chemotherapy in metastatic EGFR mutant NSCLC following progression on EGFR-TKIs. Methods: This international phase II cohort study will recruit 100 participants from Australia and Taiwan with advanced EGFR mutant NSCLC following disease progression with EGFR-TKIs [Cohort 1 (n=50): T790M mutation negative on tissue and plasma; Cohort 2 (n=50): T790M mutation positive on tissue and/or plasma, and progression on3rd generation TKIs]. Participants will receive 4 cycles of induction durvalumab 1500mg and tremelimumab 75mg with platinum-pemetrexed chemotherapy every 3 weeks, followed by maintenance durvalumab 1500mg and pemetrexed 500mg/m2 every 4 weeks until disease progression. Response will be assessed at 6 and 12 weeks, then 8-weekly during the first year, and 12-weekly thereafter. Major endpoints include objective tumour response rate (OTRR; RECIST1.1; primary), disease control rate, OTRR (iRECIST), progression-free survival, overall survival, and adverse events. Correlative studies include biomarker assessment as potential predictive/prognostic factors. ILLUMINATE is a collaboration between the Australasian Lung Cancer Trials Group, National Health Research Institutes (Taiwan) and the NHMRC Clinical Trials Centre, University of Sydney. As of 6/2/2020, 11 of planned 100 participants have been recruited. Clinical trial information: NCT03994393 .

CtDNA levels before treatment predict survival in non-small cell lung cancer patients treated with a tyrosine kinase inhibitor.

9542 Background: Currently there is an intense debate concerning therapeutic strategies in EGFR positive NSCLC patients with advance disease. Osimertinib is superior to standard EGFR Tyrosine Kinase Inhibitors (TKIs) as first line treatment. However, it is yet unclear whether this option is superior to sequential treatment of a 1st or 2nd generation TKI followed by osimertinib. In order to clarify this issue it is important to identify which patients are at high risk of progression disease. Methods: This is a prospective, multicentre, cross-sectional study promoted by Spanish Lung Cancer Group. 698 plasma samples from 196 advanced NSCLC patients with tumors harboring an EGFR activating mutation and treated with a first line TKI (afatinib, gefitinib, erlotinib or osimertinib) were analyzed. Plasma samples were prospectively collected before treatment (T0), after 3 months of treatment (T3), after 6 months of treatment (T6) and at first disease progression. EGFR mutations were analyzed by dPCR. Multivariate Cox proportional hazards analysis was used to determine the significance of ctDNA in the prediction of prognosis. Results: The median follow up was 19.8 months. At baseline patients with plasma EGFR sensitizing mutations at allele frequency (AF) ≥ 10% had worse OS and PFS than patients in which the opposite occurred (HR = 1.86; 95 %CI: 1.09-3.17, and HR = 1.65; 95 %CI: 1.07-2.58, respectively). Noteworthy, median OS and PFS time were 18.6 and 8.8 months respectively, in patients with plasma AF≥10% before treatment initiation compared to 37.9 and 12.4 months for patients with plasma AF < 10%. Similar results were obtained when a cutoff of AF≥ 5% was used (HR = 1.73; 95%CI: 1.02-2.94 for OS, and HR = 1.72; 95%CI: 1.13-2.61 for PFS). Patients who remained ctDNA-positive after 3 months of treatment exhibited also poorer outcomes (HR = 3.24; 95%CI: 1.77-5.94 for OS, and HR = 3.1; 95%CI: 1.91-5.03 for PFS). In the same way, detectable levels of ctDNA after 6 months of treatment predicted shorter OS and PFS (HR = 3.3; 95%CI: 1.53-7.13 and HR = 2.62; 95%CI: 1.62-4.25, respectively). Conclusions: ctDNA levels significantly predict survival. Moreover, ctDNA levels before treatment initiation can be useful to assess patient’s progression risk which is not possible to assess otherwise facilitating treatment decision making.

Upfront or delayed radiation with next generation tyrosine kinase inhibitor therapy in driver mutation positive NACLC brain metastasis.

e14503 Background: NSCLC with driver mutations may be managed with SRS, WBRT, and TKIs. Prior studies have demonstrated a worse survival with a delay in brain radiotherapy. We sought to determine if there is a difference in CNS PFS, OS, and cumulative incidence of intracranial brain failure (CI IBF) with next generation TKIs. Methods: A total of 69 patients with driver mutation NSCLC patients with brain metastasis were included. CNS PFS was measured from brain metastasis diagnosis. CI ICF was measured as any new or progressive disease on MRI Brain imaging. Results: The 1 year OS was 65.7% vs 60% (p = 0.9) for the RT and TKI arms. The CNS PFS was 82% vs 72% and CI ICF 13.5% vs 22% in the RT vs TKI arms, respectively. Conclusions: There was no difference in overall survival in our cohort when giving TKI therapy upfront or delayed with radiation. There was a clinically meaningful improvement in CNS PFS at 1 year but was not significant. There findings warrant further study.

Comparison of treatment outcomes in patients with metastatic lung cancer who did or did not develop EGFR T790M mutation.

e21658 Background: First-line treatment of lung cancer patients with EGFR mutation with early generation tyrosine kinase inhibitors (TKIs) renders a median progression-free survival (mPFS) of 11 months (m), and for the patients who subsequently develop the T790M mutation, osimertinib provides an additional mPFS of 10 m. First-line treatment with osimertinib showed mPFS of 18.9 m and none developed T790M at the time of progression (FLAURA trial). We hypothesized that the mPFS for patients who developed T790M mutation might be longer than those who did not and the prognosis and outcome might be different between these two groups. Methods: This is a retrospective study on patients who were diagnosed with metastatic, EGFR-mutated NSCLC and treated at Maimonides Cancer Center between 1/1/2011 and 9/30/2019. Patients were divided into two cohorts: those who did not develop T790M mutation (group 1), and those who did (including 1 patient who had de novo mutation, group 2). Results: Fifty-six patients were identified, with median age of 70 years (range 40-93). All patients had adenocarcinoma. Thirty-nine (70%) were Chinese. There were 31 (55%) exon 19 deletion, 22 (39%) L858R, 1 E709A, 1 G719S and 1 de novo T790M mutations. Forty-five patients (80%) never developed T790M (group 1), 10 (18%) did and 1 had primary mutation (group 2). The median time to developing T790M mutation was 22 m. In group 1, 8 patients received first-line osimertinib, while other 37 received erlotinib (23), gefitinib (4) and afatinib (10). Among the 37 patients, 12 were switched to osimertinib in subsequent lines, 5 due to toxicity and 7 due to progression. In group 2, 8 patients received osimertinib at identification of T790M and 1 for de novo mutation. At 22 m median follow up, the mPFS for group 1 was 14 m (95% CI 9.3-19); the mPFS for group 2 was 21.6 m (95% CI 7.4-49.1) up to the time of identification of T790M, and 31.2 m (95% CI 4.9-45.4) until disease progression after osimertinib. The mPFS of the entire cohort was 17.1 m (95% 11.1-25.9), and mOS was 22.0 m (95% 15.6-29.6). The mOS was 19.0 m (95% CI 11.4 – 25.2), and 39.9 m (95% CI 13.3 – 62.1) for group 1 and 2 respectively. Conclusions: Patients who developed the T790M mutation appeared to have a longer PFS than those who did not and the mean duration to detection of T790M was 22 m. The development of T790M may confer a slower growth pattern and longer PFS. This question should be further explored in larger studies.

Does CNS metastases reduce systemic therapy lines for NSCLC patients with EGFR mutation?

e21558 Background: The latest generation tyrosine kinase inhibitor (TKI), Osimertinib, targets the epidermal growth factor receptor (EGFR) despite the T790M mutation status in non-small-cell lung cancer (NSCLC). In cases where there is a detected EGFR mutation on the exon 19-deletion and on the exon 21-L858R in the NSCLC population, studies have demonstrated that Osimertinib has a positive benefit in overall survival and delayed progression of central nervous system (CNS) metastases. Methods: From January 2010 to December 2018, 56 patients with the metastatic NSCLC-EGFR mutation, treated with Osimertinib 80 mg once daily, were included in this analysis. Retrospective data was extracted through the internal administrative databases located at Sunnybrook Hospital. All patients had EGFR mutation positivity by cytology, plasma or tissue sampling. The primary endpoint was to evaluate whether NSCLC patients who were exposed to Osimertinib and had brain metastases underwent fewer systemic therapy lines as compared to those who did not have metastases involving the brain. Results: Eligible patients were analyzed and the median age at the initial diagnosis was 65 years old; 50% (n = 28) of the patients had brain metastases. The median of systemic treatment lines for patients without CNS metastasis was two and for those who have metastases to the brain was three. 82,2% of this cohort received Osimertinib in 2nd line, after development of acquired resistance to first or second TKI generation. Conclusions: Results from this study did not demonstrate that EGFR mutated, NSCLC patients with CNS metastases received less systemic therapy lines to those without metastases involving the brain. A larger cohort for further investigation is warranted.

COVID-19 in persons with chronic myeloid leukaemia.

We studied by questionnaire 530 subjects with chronic myeloid leukaemia (CML) in Hubei Province during the recent SARS-CoV-2 epidemic. Five developed confirmed (N = 4) or probable COVID-19 (N = 1). Prevalence of COVID-19 in our subjects, 0.9% (95% Confidence Interval, 0.1, 1.8%) was ninefold higher than 0.1% (0, 0.12%) reported in normals but lower than 10% (6, 17%) reported in hospitalised persons with other haematological cancers or normal health-care providers, 7% (4, 12%). Co-variates associated with an increased risk of developing COVID-19 amongst persons with CML were exposure to someone infected with SARS-CoV-2 (P = 0.037), no complete haematologic response (P = 0.003) and co-morbidity(ies) (P = 0.024). There was also an increased risk of developing COVID-19 in subjects in advanced phase CML (P = 0.004) even when they achieved a complete cytogenetic response or major molecular response at the time of exposure to SARS-CoV-2. 1 of 21 subjects receiving 3rd generation tyrosine kinase-inhibitor (TKI) developed COVID-19 versus 3 of 346 subjects receiving imatinib versus 0 of 162 subjects receiving 2nd generation TKIs (P = 0.096). Other co-variates such as age and TKI-therapy duration were not significantly associated with an increased risk of developing COVID-19. Persons with these risk factors may benefit from increased surveillance of SARS-CoV-2 infection and possible protective isolation.

A user’s guide to lorlatinib

Rearrangements of the ALK gene are found in approximately 5% of non-small-cell lung cancer. It is of particular importance to test for this rearrangement in patients with metastatic lung adenocarcinoma because these tumors are highly sensitive to therapy with ALK-targeted inhibitors. Lorlatinib is a reversible potent third generation tyrosine kinase inhibitor that is highly selective and targets ALK and ROS1. It was developed to target resistant ALK mutants including the most common G1202R. Lorlatinib has excellent central nervous system (CNS) penetration and its efficacy has also been demonstrated even in patients with intracranial metastases after progression on second generation ALK inhibitors. Potential toxicities include neurocognitive effects and hyperlipidemia. "A User's Guide to Lorlatinib" reviews the mechanism of action, pharmacology and clinical trial data. Also covering the management of adverse events, this "guide" has been prepared to be a practical reference tool to both clinicians and basic researchers.