Kura Oncology Research Articles

Combination Thioguanine and Decitabine Is Highly Active in Patients with Advanced Myeloid Malignancies: A Single Institution Experience

BACKGROUND: Despite recent advances, outcomes remain poor in secondary and relapsed/refractory (R/R) acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). We previously demonstrated that combination thioguanine (6TG) and decitabine restores therapeutic efficacy in vitro in R/R AML (O'Dwyer K et al. Blood 2010;114:2657). Based on these data, we completed a Phase I dose-escalation study of 6TG with decitabine in advanced myeloid malignancies with an overall response rate (ORR) of 67% and median progression-free survival (PFS) of 42 weeks in responding patients (Lee DJ, et al. Blood 2016;128:2816). Moreover, 5 of the 6 study participants who had previously received a hypomethylating agent (HMA) responded, suggesting that 6TG in combination with decitabine can overcome HMA resistance. Because of these results, a cohort of patients with high-risk and R/R AML and MDS were treated with combination 6TG and decitabine at Columbia University Irving Medical Center, and we now report our clinical experience with this regimen. METHODS: A retrospective chart review was performed of all adult patients at our institution with advanced myeloid malignancies who had received at least one cycle of 6TG and decitabine between 2013-2017. The treatment regimen utilized the maximum tolerated dose of 6TG identified in the phase I trial. Up to 2 cycles of induction with 6TG 80 mg/m2/day PO in 2 divided doses was given on Days 1-12. Decitabine 20 mg/m2 IV was given on Days 3-12. Following this, maintenance cycles consisted of 6TG on Days 1-7 and decitabine on Days 3-7 at the same doses. Treatment was continued until the time of hematopoietic stem cell transplant (HSCT), disease progression, or toxicity. The primary objective of this retrospective analysis was to determine the ORR. Secondary objectives were to evaluate PFS and overall survival (OS) in this population. RESULTS: Forty-two patients were identified, 55% of whom were female, with a median age of 68 years (range, 23-83 years). Thirty-three percent of the patients had secondary AML; 62% had R/R AML; 2% had R/R MDS; and 2% had chronic myelomonocytic leukemia. By ELN genetic risk stratification, 38% were adverse-risk, 43% were intermediate, and 17% were favorable, while 2% were unknown. However, 36 (86%) patients failed prior therapy, suggesting that nearly all of the treated patients were poor-risk. Nineteen (45%) patients had received prior HMA therapy, and 6 (14%) had undergone previous HSCT. Patients received a median of 2 cycles of therapy (range, 1-10). Five (12%) patients achieved complete remission (CR), 7 (16%) obtained a CR with incomplete count recovery (CRi/p), and 2 (5%) had morphologic leukemia-free state (MLFS), for an ORR of 33% (CR+CRi/p+MLFS). One notable patient who achieved CR was a 73-year-old with secondary AML, complex cytogenetics, and a TP53 mutation who subsequently went on to HSCT. Another 5 (36%) responders had complex karyotypes or poor-risk genetics. Ten of the 14 responders (71%) failed prior therapy. Of the 19 who had received prior HMA therapy, 6 (32%) responded. Six of 14 (43%) responders proceeded to HSCT. Two additional patients had significant blast reduction and underwent HSCT. Responses and maximum blast reduction were obtained after two cycles of therapy. For the responders, the median PFS was 38 weeks (range, 11-not reached), while the median OS was 43 weeks (range, 11-not reached). CONCLUSIONS: Combined 6TG and decitabine is a highly active regimen in advanced myeloid malignancies, with an ORR of 33% in this cohort, and median PFS and OS of 38 and 43 weeks, respectively, in responding patients. This compares favorably to the expected response rate of 10-20% with decitabine monotherapy in this poor-risk population consisting of mostly secondary and R/R AML. These data also confirm our prior phase I study findings that the addition of 6TG to decitabine can overcome prior HMA resistance, with 32% of those who had previously failed HMA therapy responding. This combination remains a viable therapeutic option for elderly and unfit patients with high-risk and R/R AML who cannot tolerate intensive chemotherapy. Disclosures Heaney: BMS: Research Funding; Partner Therapeutics: Consultancy; Roche: Consultancy, Research Funding; Incyte: Consultancy, Research Funding; Celgene: Research Funding; Novartis: Consultancy; AbbVie: Consultancy; Deciphera: Research Funding; Constellation: Research Funding; Blueprint: Research Funding; CTI: Research Funding. Lamanna:Ming: Research Funding; Celgene: Consultancy; Oncternal: Research Funding; TG Therapeutics: Research Funding; Infinity/ Verastem: Research Funding. Jurcic:Syros Pharmaceuticals: Research Funding; Astellas: Research Funding; AbbVie Inc: Consultancy; Daiichi Sankyo: Research Funding; Celgene: Consultancy, Research Funding; Incyte: Consultancy; Kura Oncology: Research Funding; Forma Therapeutics: Research Funding; Genentech: Research Funding; Novartis: Consultancy; Actinium Pharmaceuticals: Research Funding. Frattini:Celgene: Employment, Equity Ownership; Lin Bioscience: Consultancy. Lee:Abbvie: Research Funding; Roche: Research Funding; Tolero: Research Funding; Forty Seven, Inc.: Research Funding; Bayer: Research Funding.

Symptom Assessment in Patients with BCR-ABL-Negative Myeloproliferative Neoplasms at an Academic Medical Institution

Symptom Assessment in Patients with BCR-ABL-Negative Myeloproliferative Neoplasms at an Academic Medical Institution

A Phase 1b Study Evaluating the Safety and Efficacy of Venetoclax in Combination with Azacitidine in Treatment-Naïve Patients with Higher-Risk Myelodysplastic Syndrome

A Phase 1b Study Evaluating the Safety and Efficacy of Venetoclax in Combination with Azacitidine in Treatment-Naïve Patients with Higher-Risk Myelodysplastic Syndrome

Role of Vav1 Genomic Alterations in T-Cell Differentiation and Transformation in Peripheral T-Cell Lymphoma

Peripheral T-cell lymphomas (PTCL) are highly aggressive, malignant hematologic tumors that arise from clonal proliferation of mature post-thymic T-cells. Among these, angioimmunoblastic T-cell lymphoma (AITL), and peripheral T-cell lymphomas not otherwise specified (PTCL, NOS) account for >45% diagnoses, show limited response to intensified chemotherapy treatment with dismal overall survival rate. Our genomic studies have uncovered recurrent mutations and novel cancer-associated gene fusions involving the guanine nucleotide exchange factor VAV1 in AITL and PTCL, NOS, supporting a role for the VAV1 oncogene in the pathogenesis of PTCL. Genetic alterations in VAV1 found in PTCL included recurrent deletions resulting in the in-frame deletion of 9 codons (DV778_T786) in the linker region connecting the C-terminal SH2 domain to the downstream SH3 domain on VAV1 as well as recurrent different gene-fusion transcripts encoding proteins in which the C-terminal SH3 domain of VAV1 is replaced by different domains of the fusion partner. Consistent with the auto-inhibitory role of the C-SH3 domain, the PTCL-associated VAV1 alterations resulted in increased VAV1 activity and strong activation of the mitogen-activated protein kinase (ERK1/2), c-Jun N-terminal kinase (JNK) and nuclear factor of activated T-cells (NFAT) pathways. Interestingly, mutation co-occurrence analysis shows significant mutual exclusivity of the highly prevalent AITL RHOA G17V mutation and VAV1 genomic alterations (p-value 0.0142) in AITL and PTCL, NOS. This observation supports that VAV1 genetic alterations and RHOA G17V could share a common mechanism of action. To study the role and mechanisms of VAV1 alterations in PTCL in vivo we have engineered a C57/BL6 mouse lines with conditional expression of the recurrent Vav1-Myo1f fusion. By crossing Vav1-myo1f conditional knockin with CD4-CreERT2 mouse deletor line, we have generated animals with CD4+ T cell-specific and tamoxifen-inducible expression of Vav1-myo1f. Preliminary studies indicate that expression of Vav1-myo1f in CD4+ cells induces expansion of TFH cells. This phenotype partially resembles that of animals with CD4 specific expression of Rhoa G17V, indicating a potential convergent effect and mechanisms for VAV1 alterations and RHOA G17V in T-cell development and transformation. However, and more interestingly, Vav1-myo1f expressing cells specifically present a memory cell-associated immunophenotype (CD44+ CD62L-) and characteristic Th2-like features that had not been observed in the Rhoa G17V model. Analysis of signaling pathways activated in control and Vav1-myo1f expressing CD4+ cells showed increased phosphorylation of Vav1 and increased activation of the MAPK pathway upon expression of Vav1-myo1f, supporting the role of Vav1 alterations as regulators of T-cell activation. Notably, single cell transcriptome analysis of bulk splenic cells isolated from CD4-CreERT2 control and CD4-CreERT2Vav1co-Vav1-myo1f/WT mice indicate that expression of Vav1-myo1f in CD4+ cells leads to a significant expansion of monocytes and TFH cells and a decrease in B-cell, both naïve and memory. These results support that expression of Vav1-myo1f in CD4+ cells can deeply modify the lymphoid microenvironment. Finally, preliminary analysis of a limited number of mice with targeted expression of the Vav1-Myo1f fusion in CD4+ cells (CD4-Cre Vav1co-Vav1-Myo1f /WT) showed development of a fatal CD4+ malignant lymphoproliferation with a latency of 6-14 months. Histological examination showed disrupted splenic architecture accompanied with clonal expansion of CD4+ cells indicative of T-cell lymphoma with PTCL, NOS characteristics and verified expression of both wild type Vav1 and Vav1-myo1f alleles. Interestingly, Vav1-myo1f lymphoma cells showed Th2 associated features including expression of Gata3, c-Maf and IL4 and Il10. These results support an important role for VAV1 alterations in T-cell differentiation, remodeling of the tumor microenvironment and T-cell lymphoma development and highlight the importance of our model as a new experimental system to study the evolution of PTCL and develop novel targeted therapies for this disease. Disclosures Palomero: Kura Oncology: Research Funding.

125O - Pembrolizumab + chemotherapy for advanced G/GEJ adenocarcinoma (GC): The phase III KEYNOTE-062 study

125O - Pembrolizumab + chemotherapy for advanced G/GEJ adenocarcinoma (GC): The phase III KEYNOTE-062 study

1128P - Final results of a phase II study of induction chemotherapy (CT) with paclitaxel (PTX) and panitumumab (P) followed by radiotherapy (RT) and P in patients (pts) with locally advanced head and neck cancer (LAHNC) no candidates to platinum: Study PANTERA

BackgroundPatients (pts) not candidates to platinum-based therapies have limited therapeutic options. The addition of P to PTX followed by RT + P may be an alternative to platinum-based therapy. This study aimed to evaluate the activity of P + PTX as induction treatment (Tx) in pts with LAHNC. MethodsPhase II, single arm, multicenter study, in pts≥18 years with CT/RT-naive stage III-IVb LAHNC not candidates to aggressive Tx. All pts received PTX (80mg/m2/week [w]) + P (6mg/kg every 2w) during 9w as induction Tx followed by P and RT (70Gy/35 fractions/7w).The primary endpoint was RR after induction Tx. With a Simon’s two stage design, p1 at the end of the study was defined as>36 of 61 patients achieving complete (CR) or partial response (PR) to induction Tx. ResultsThe study included 51 pts: median 70 years (range 45-84), 98% men. Reasons for cisplatin ineligibility: > 70 years old in 3 pts, mild or moderate adult comorbidity [ACE-27 comorbidity index] in 46 pts, severe adult comorbidity in 1pt and ECOG: 2 in 1pt. RR after induction was 66.7% (95% confidence interval [CI]: 53.7-79.6): 8 (15.7%) CR and 26 (51.0%) PR. Median progression-free survival was 12.2 months (m) (95% CI: 7.6 - 35.0] and median overall survival was 31.5 m (95%: 14.3 - not reached) with a median duration of follow-up of 31.9 m (range, 1-61). Incidence of grade 3/4 P and/or PTX-related Adverse Events (AEs) was 72.5%. Most frequent grade 3/4 P and/or PTX- related AEs (>5% of pts) were: 5.9% dermatitis, 5.9% neutropenia, 5.9% dry mouth, 5.9% stomatitis, 7.8% asthenia, 15.7% eruption, 15.7% skin toxicity and 27.5% mucosal inflammation. Five (9.8%) pts had fatal AEs, 2 (3.9%) of them related to P and/or PTX. ConclusionsDespite the study ended prematurely, the RR observed is higher than the pre-specified boundary to consider the treatment active to justify further studies. PTX combined with P as induction Tx provide a clinically significant benefit with an acceptable safety profile. Clinical trial identification2012-003038-17. Editorial acknowledgementMarta Muñoz-Tudurí (TFS, S.L.). Legal entity responsible for the studyStudy carried out by Grupo Español de Tratamiento de Tumores de Cabeza y Cuello (TTCC). FundingAmgen S.A. DisclosureJ. Martinez Trufero: Advisory / Consultancy: PharmaMar, Merck, Lilly, Eisai, Bristol-Myers; Honoraria (self), Medical meetings sponsor: PharmaMar, Merck, Lilly, Eisai. R. Mesia Nin: Advisory / Consultancy: Merck, BMS, MSD, AZ, Roche, Nanobiotix; Speaker Bureau / Expert testimony: Merck, BMS, MSD. M. Taberna Sanz: Non-remunerated activity/ies: Merck; Non-remunerated activity/ies: AstraZeneca; Honoraria (self): Merck; Honoraria (self): Nanobiotics; Honoraria (self): MSD; Honoraria (self): Bristol Myers. J. Lambea Sorrosal: Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: Merck-Serono, MSD, Bristol. All other authors have declared no conflicts of interest. L. Iglesias: Honoraria (self), Advisory / Consultancy: Merck Serono, MSD, BMS, Bayer, Sanofi; Honoraria (self), medical education with honoraria: Merck Serono, MSD, AstraZeneca y BMS; Research grant / Funding (institution): Merck Serono, MSD, AstraZeneca, BMS, Novartis, Kura Oncology, Sanofi y Kura Oncology. P. Perez Segura: Speaker Bureau / Expert testimony: BMS, Merck. J.J. Cruz-Hernández: Honoraria (self): Amgen, AstraZeneca, Bristol-Myers Squibb, Novartis, Pfizer, Roche; Advisory / Consultancy, Advisory Board: Bristol-Myers Squibb, Merck, MSD, Roche, Pfizer, Janssen Cilag; Advisory / Consultancy, Consulting: Roche.

1886P - Prospective pathological experience with research biopsies in the context of clinical trials at Vall d’Hebron Institute of Oncology

1886P - Prospective pathological experience with research biopsies in the context of clinical trials at Vall d’Hebron Institute of Oncology

135P - Can we improve patient selection for phase I clinical trials (phI1) based on immuno-oncology score prognostic index (VIO)?

BackgroundLife expectancy longer than 12 weeks(w) is a common inclusion criteria for most Ph1. Despite the presence of several prognostic indeces in drug development, their value for patient selection in clinical trials is not well established. VIO is a immune-oncology score validated in patients treated in Ph1 with immunotherapy (Hierro C. ESMO 2018), which includes 5 variables: albumin<35g/L, lactate dehydrogenase > upper limit normal, dNLR (derived neutrophil/(leukocytes minus neutrophils) ratio) >3, >2 sites of metastases, and presence of liver metastases. MethodsVIO variables were retrospectively collected from 384 patients with advanced disease treated in Ph1 with immune checkpoint inhibitors (ICIs) or targeted agents (TAs) since 2011 to 2017 at Vall d´Hebron Hospital. The following VIO clusters were defined based on Kaplan Meier OS estimates: good prognosis (0‐1), intermediate (2‐3) and poor prognosis (4‐5). We aimed to improve patient selection for Ph1 (independent of treatment type) by developing a composite VIO score that is associated with overall survival (OS), progression free survival (PFS) and objectively estimated life expectancy at 12 w. ResultsFrom the 384 patients treated with ICIs (53.6%) or TAs (45.4%) in Ph1, 206 (53.6%) were female, 210 were treated with monotherapy (54.7%). Most frequent tumor types were: colorectal (17.4%), breast (14.1%) and lung (9.4%). The median follow-up was of 8.4 months (m) [IC95% 7.3-9.5]. Estimated median OS in good prognosis (33.3% of all pts), intermediate (54.2%) and poor prognosis (12.5%) was 16.2 m (13.3‐19.1), 7.8 m (6.9‐8.6) and 2.9 m (2.1-3.8), respectively (log rank test, p<0.001), while the median PFS was 3.3 m (2.6‐3.9), 1.9 m (1.7‐2.1) and 1.2 m (0.8-1.6), respectively (log rank test, p<0.001). Proportions of patients with life expectancy < 12 w were 52.2%, 13.1% and 4.3% in poor, intermediate and good prognosis VIO score groups, respectively (chi square<0.001). ConclusionsVIO score is a strong prognostic index independent of the treatment type and it could be useful as a tool to estimate objectively life expectancy <12 w. More than 50% of patients with VIO score 4-5 (poor prognosis) died within 12 w, an estimate that can guide recruitment in phase 1 trials. Legal entity responsible for the studyThe authors. FundingThis research has been funded by the Comprehensive Program of Cancer Immunotherapy & Immunology (CAIMI) supported by the Banco Bilbao Vizcaya Argentaria Foundation (FBBVA) (grant 89/2017). DisclosureJ. Martin-Liberal: Advisory / Consultancy: Bristol-Myers Squibb, Novartis, Pierre Fabre, Roche; Speaker Bureau / Expert testimony: Astellas, Bristol-Myers Squibb, MSD, Novartis, Pierre Fabre, Pfizer, Roche; Honoraria (self): Bristol-Myers Squibb, MSD, Novartis, Pierre Fabre, Pfizer, Roche, Ipsen. A. Azaro: Honoraria (self), Advisory / Consultancy: Novartis, Roche, Orion. I. Brana: Advisory / Consultancy: Orion pharma; Speaker Bureau / Expert testimony: BMS; Speaker Bureau / Expert testimony: AstraZeneca; Speaker Bureau / Expert testimony: Merck Serono; Research grant / Funding (self): AstraZeneca, BMS, Celgene, Gliknik, GSK, Janssen, KURA, MSD, Novartis, Northern Biologics, Orion Pharma, Pfizer, Roche.. M. Vieito Villar: Honoraria (self), Travel grant: Roche. E. Muñoz-Couselo: Advisory / Consultancy: Amgen, Bristol-Myers Squibb, Merck, Sharp & Dohme, Novartis, Pierre Fabre, and Roche; Honoraria (self): Amgen, Bristol-Myers Squibb, Merck, Sharp & Dohme, Novartis, Pierre Fabre, Sanofi and Roche. E. Elez Fernández: Honoraria (institution): Array, MSD, Abbvie, Amgen, GSK, AstraZeneca,Bristol-Myers Squibb, Novartis, Boehringer Ingelheim, Hoffman La-Roche; Advisory / Consultancy: Hoffman La-Roche, Bristol-Myers Squibb, Servier, Amgen, Merck Serono, Array, Sanofi. E. Felip: Advisory / Consultancy, Speaker Bureau / Expert testimony: AbbVie, AstraZeneca, Blueprint medicines, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Eli Lilly, Guardant Health, Janssen, Medscape, Merck KGaA, Merck Sharp & Dohme, Novartis, Pfizer, Roche, Takeda, Touchtime; Research grant / Funding (self): Fundación Merck Salud, Grant for Oncology Innovation EMD Serono.. J. Carles: Research grant / Funding (self): AB Science, Aragon Pharmaceuticals, Arog Pharmaceuticals, INC, Astellas Pharma., AstraZeneca AB, Aveo Pharmaceuticals INC, Bayer AG, Blueprint Medicines Corporation, BN Immunotherapeutics INC, Boehringer Ingelheim España, S.A., Bristol-Myers Squibb Inter; Advisory / Consultancy: Bayer / Johnson & Johnson / Bristol-Myers Squibb / Astellas Pharma / Pfizer / Sanofi / MSD Oncology / Roche/ AstraZéneca; Speaker Bureau / Expert testimony: Bayer / Johnson & Johnson / Asofarma / Astellas Pharma. J. Tabernero: Advisory / Consultancy: Array Biopharma, AstraZeneca, Bayer, BeiGene, Boehringer Ingelheim, Chugai, Genentech, Inc., Genmab A/S, Halozyme, Imugene Limited, Inflection Biosciences Limited, Ipsen, Kura Oncology, Lilly, MSD, Menarini, Merck Serono, Merrimack, Merus, Molecular Part. R. Dienstmann: Advisory / Consultancy: Roche; Speaker Bureau / Expert testimony: Roche, Symphogen, Ipsen, Amgen, Sanofi, MSD, Servier; Research grant / Funding (self): Merck. E. Garralda: Advisory / Consultancy: F.Hoffmann-La Roche,Ellipses Pharma ,Neomed Therapeutics1 Inc,Boehringer Ingelheim ,Janssen Global Services; Speaker Bureau / Expert testimony: Bristol-Mayers Squibb; Honoraria (self): Menarini, Glycotope, Menirarini. All other authors have declared no conflicts of interest.

685TiP - A phase II basket study of MCLA-128, a bispecific antibody targeting the HER3 pathway, in NRG1 fusion-positive advanced solid tumours

685TiP - A phase II basket study of MCLA-128, a bispecific antibody targeting the HER3 pathway, in NRG1 fusion-positive advanced solid tumours

575P - RAS mutant allele fraction in plasma predicts benefit to anti-angiogenic based first-line treatment in metastatic colorectal cancer

BackgroundSo far, no biomarkers of response to anti-angiogenic drugs are available in colorectal cancer (CRC) treatment. Liquid biopsy technique identifies actionable targets in CRC patients (pts), tracking dynamic mutational changes. We and others described RAS mutant allele fraction in plasma (plMAF) as an independent prognostic marker in metastatic CRC (mCRC). Here, we explored the predictive value of plMAF in RAS mutant pts treated in first line with chemotherapy +/- bevacizumab (bev). MethodsA multicentric prospective/retrospective analysis was conducted. We collected data from 226 mCRC pts and selected the subset not eligible for metastasis resection that had basal plMAF sample evaluable for RAS mutant MAF quantification using digital PCR (BEAMing). Pts were stratified as high (≥ 5.8%) or low (< 5.8%) plMAF based on previously defined cut-off (Sanz-Garcia E, ESMO GI, 2017). We investigated associations between different clinicopathological variables (gender, n° and site of metastases, CEA levels, primary site location) and progression-free survival (PFS) stratified by plMAF RAS levels using Cox regression models and survival data were calculated by the Kaplan-Meier method. ResultsFrom October 2017 to May 2019, BEAMing analysis from 62 basal plasma samples was performed. 42 pts (67.7%) were classified as high and 20 pts (32,3%) as low plMAF. Among high RAS plMAF, 24 pts received FOLFOX+bev (57%) and 20 pts FOLFOX alone (43%). In this high plMAF subgroup, a statistically significant longer PFS favouring FOLFOX+bev was observed when compared to FOLFOX alone (10.7 versus 6.9 months, respectively; HR: 0.30; p=0.002). In the low RAS plMAF subgroup, no differences in terms of PFS were observed in either arm (8.9 versus 8.7 months, respectively; HR: 0.70; p=0.6). Multivariate PFS model showed no association between RAS plMAF and clinicopathological variables, except for high RAS plMAF and treatment benefit with FOLFOX+bev. ConclusionsOur results indicate that tumor-borne RAS plMAFs may constitute a potential predictive biomarker of efficacy for anti-angiogenic agents in mCRC. Confirmatory studies in randomized cohorts will be performed. Legal entity responsible for the studyVHIO (Vall d’Hebron Institute of Oncology). FundingAECC (Asociación Española Contra el Cáncer). DisclosureG. Martini: Research grant / Funding (self), Research Project supported by ESMO with the aid of a grant from Amgen: ESMO-AMGEN. E. Elez: Honoraria (self): Merck Serono; Honoraria (self): Sanofi; Honoraria (self): MSD; Honoraria (self): Roche; Honoraria (self): Servier; Honoraria (self): Amgen; Honoraria (self): Array. G. Argiles Martinez: Honoraria (self), Honoraria (institution), Research grant / Funding (self), Travel / Accommodation / Expenses: Hoffmann-LaRoche, Bristol-Myers Squibb, Bayer, Servier, Amgen, Merck Serono, Menarini; Honoraria (self): Menarini; Honoraria (institution): Boston Pharmaceuticals; Honoraria (institution): Genentech; Honoraria (institution): Boehringer Ingelheim. M.J. Ortiz Morales: Speaker Bureau / Expert testimony: Amgen; Speaker Bureau / Expert testimony: Roche; Speaker Bureau / Expert Testimony: Sanofi. P.G. Nuciforo: Honoraria (self): BAYER; Honoraria (self): MSD; Honoraria (self): Novartis. R. Dienstmann: Advisory / Consultancy, Speaker Bureau / Expert testimony: Roche; Speaker Bureau / Expert testimony: Symphogen, Ipsen, Amgen, Sanofi, MSD, Servier; Research grant / Funding (self): MERCK. J. Tabernero: Advisory / Consultancy: Array Biopharma, AstraZeneca, Bayer, BeiGene, Boehringer Ingelheim, Chugai, Genentech, Inc., Genmab A/S, Halozyme, Imugene Limited, Inflection Biosciences Limited, Ipsen, Kura Oncology, Lilly, MSD, Menarini, Merck Serono, Merrimack, Merus, Molecular Part. E. Aranda Aguilar: Advisory / Consultancy: Amgen; Advisory / Consultancy: Bayer; Advisory / Consultancy: Celgene; Advisory / Consultancy: Merck; Advisory / Consultancy: Roche; Advisory / Consultancy: Sanofi. A. Vivancos: Advisory / Consultancy: sysmex; Advisory / Consultancy: Novartis; Advisory / Consultancy: Merck; Advisory / Consultancy: Bristol-Meyers Squidd; Advisory / Consultancy: Guardant Health. All other authors have declared no conflicts of interest.

1493P - Long-term avelumab treatment in patients with advanced non-small cell lung cancer (NSCLC): Post hoc analyses from JAVELIN solid tumour

1493P - Long-term avelumab treatment in patients with advanced non-small cell lung cancer (NSCLC): Post hoc analyses from JAVELIN solid tumour

682P - Phase III, international, multicenter, randomized, open-label trial of adjuvant nab-paclitaxel plus gemcitabine (nab-P/G) vs gemcitabine (G) alone for surgically resected pancreatic adenocarcinoma (APACT): Subgroup analyses

BackgroundThe primary APACT analysis showed no significant difference in disease-free survival (DFS) by blinded, independent radiologic review with nab-P/G vs G in patients (pts) with surgically resected pancreatic cancer (PC). However, investigator-assessed DFS (prespecified sensitivity analysis) and interim overall survival (OS; secondary endpoint) trended in favor of nab-P/G. Here, we report interim OS exploratory subanalyses. MethodsTreatment-naive pts with histologically confirmed PC, macroscopic complete resection (R0/R1), CA 19-9 < 100U/mL, and ECOG PS 0 or 1 were enrolled. Stratification factors included resection (R0/R1), lymph node (LN) status (positive [+]/negative), and geographic region. Pts were treated ≤ 12 weeks after surgery with nab-P 125mg/m2 + G 1000mg/m2 or G 1000mg/m2 alone on days 1, 8, and 15 every 28 days for 6 cycles. For the primary endpoint assessment, independent reviewers received only baseline clinical data and scans. OS and safety were secondary endpoints. Ten prespecified subanalyses were performed. Results866 pts were randomized. Median age was 64 y (range, 34–86); most were male (56%) and white (78%) and had ECOG PS 0 (60%), LN+ status (72%), and R0 resection (76%). At the original data cutoff (31 December 2018; median follow-up, 38.5mo), median OS (interim) trended in favor of nab-P/G vs G (40.5 vs 36.2mo; HR 0.82; 95% CI, 0.680 - 0.996; nominal P=0.045). Pts with poor characteristics had numerically longer median OS with nab-P/G vs G: 32.5 vs 27.0mo in pts with R1 resection (n=105 and 100) and 33.8 vs 28.9mo in pts with LN+ status (n=311 and 312). This is consistent with the median OS observed with nab-P/G vs G in pts whose tumors were < 1mm to the closest margin (32.5 vs 29.7mo; n=114 and 112). Pts with both R1 resection and LN+ status had numerically longer median OS with nab-P/G vs G (30.7 vs 24.9mo; n=87 and 83). ConclusionsFinal OS data may clarify the role for adjuvant nab-P/G. Interim OS analyses suggest that continued investigation of adjuvant nab-P/G for pts with suboptimally resected PC or who may not tolerate FOLFIRINOX is warranted. Clinical trial identificationNCT01964430. Editorial acknowledgementRebecca Tweedell, MediTech Media, Ltd, funded by Celgene Corporation. Legal entity responsible for the studyThe authors. FundingCelgene Corporation. DisclosureM.A. Tempero: Advisory / Consultancy: AbbVie, Inc., Advance Medical, Inc., BioPharm Communications, Bristol-Myers Squibb, Celgene Corporation, Eisai, Inc., Ignyta, Inc., Pharmacyslics, LLC., Pharmcyte Biotech, Tocagen, Inc., Immunovia, CPRIT, AstraZeneca. M. Reni: Research grant / Funding (self): Celgene, Baxalta, Merck Serono, Helsinn; Non-remunerated activity/ies: Celgene, Baxalta, Merck Serono, Lilly, Pfizer, AstraZeneca, Novocure, Halozyme, Novartis, Shire. H. Riess: Speaker Bureau / Expert testimony: Celgene, Roche, Shire; Advisory / Consultancy: Celgene, Shire. E.M. O’Reilly: Honoraria (self), Research grant / Funding (institution): Celgene Corporation; Research grant / Funding (self): ActaBiologica, Agios, Array, AstraZeneca, Bayer, Beigene, BMS, Casi, Exelixis, Genentech, Halozyme, Incyte, Lilly, Mabvax, Novartis, OncoQuest, Polaris Puma, QED, Roche. S. Krishnamurthi: Non-remunerated activity/ies, Research Funding: Taiho, CytomX, Regeneron, Celgene, AbbVie. P. Österlund: Advisory / Consultancy: Amgen; Bayer; Celgene; Eisai; Lilly; Merck Serono; Roche; Sanofi; Servier/Shire; Speaker Bureau / Expert testimony: Prime Oncology; Research grant / Funding (institution): Amgen (Inst); Bristol-Myers Squibb (Inst); Celgene (Inst); Lilly (Inst); Merck Serono (Inst); MSD (Inst); Nordic Drugs (Inst); Roche (Inst); Sanofi (Inst); Servier (Inst); Travel / Accommodation / Expenses: AbbVie, Pierre Fabre. M. Milella: Advisory / Consultancy: Pfizer; Speaker Bureau / Expert testimony: AstraZeneca, EUSA Pharma. S. Siena: Advisory / Consultancy: Amgen, Bayer, BMS, CheckmAb, Celgene, Daiichi-Sankyo, Incyte, Merck, Novartis, Roche-Genentech, and Seattle Genetics. J. Tabernero: Advisory / Consultancy, Personal Financial Interest: Array Biopharma, AstraZeneca, Bayer, BeiGene, Boehringer Ingelheim, Chugai, Genentech, Inc., Genmab A/S, Halozyme, Imugene Limited, Inflection Biosciences Limited, Ipsen, Kura Oncology, Lilly, MSD, Menarini, Merck Serono, Merrimack, Merus, Molecular Part. E. Van Cutsem: Advisory / Consultancy: Bayer, Lilly, Roche, Servier, Bristol-Myers Squibb, Celgene, Merck Sharp & Dohme, Merck KGaA, Novartis, AstraZeneca; Research grant / Funding (self): Amgen, Bayer, Boehringer Ingelheim, Lilly, Novartis, Roche, Celgene, Ipsen, Merck, Merck KGaA, Servier, Bristol-Myers Squibb. P.A. Philip: Research grant / Funding (self): Celgene, Bayer, and Incyte; Speaker Bureau / Expert testimony: Roche, Sanofi, and Amgen; Advisory / Consultancy: Celgene Corporation. D. Goldstein: Advisory / Consultancy, Research grant / Funding (institution): Celgene Corporation, Pfizer. J.D. Berlin: Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Celgene Corporation. M. Li: Shareholder / Stockholder / Stock options, Full / Part-time employment: Celgene Corporation. S. Ferrara: Shareholder / Stockholder / Stock options, Full / Part-time employment: Celgene Corporation. Y. Le Bruchec: Shareholder / Stockholder / Stock options, Full / Part-time employment: Celgene Corporation. D. McGovern: Shareholder / Stockholder / Stock options, Full / Part-time employment: Celgene Corporation. A. Biankin: Leadership role: Gene Forward Inc; Research grant / Funding (self): Celgene, AstraZeneca; Licensing / Royalties: Agilent; Honoraria (self): Celgene, AstraZeneca, Tusk, Astar; Travel / Accommodation / Expenses: Celegene, AstraZeneca, Roche; Speaker Bureau / Expert testimony: Celgene, AstraZeneca, Tusk, Astar, Roche. All other authors have declared no conflicts of interest.

559P - Bevacizumab as adjuvant treatment for colon cancer: Updated results from the AVANT phase III study by the GERCOR group

559P - Bevacizumab as adjuvant treatment for colon cancer: Updated results from the AVANT phase III study by the GERCOR group

1139P - Sensitizing HRAS overexpressing head and neck squamous cell carcinoma (HNSCC) to chemotherapy

BackgroundHRAS is mutated or overexpressed in various cancers. Although numerous studies have demonstrated that HRAS mutations (HRASmut) promote chemoresistance in HNSCC, the effect of wild type HRAS overexpression (wtHRASov) on chemotherapy has not yet been studied. We sought: i. to investigate the repair capacity of wtHRASov tumors in cisplatin- induced damage and ii. to explore the cisplatin sensitizing effect of HRAS inhibitor tipifarnib. MethodsMutation/RNA and cisplatin IC50 data were retrieved from the Cancer Genome Atlas (TCGA) and COSMIC Cell Lines Project respectively. Modified Z-score was used to define HRAS overexpression. Patient derived xenografts (PDXs) were generated from treatment naïve HNSCC patients. Mutational and expression profile of tumor grafts was identified by whole exome sequencing, IHC, qRT-PCR and western blot analysis. Cisplatin or cisplatin combined with tipifarnib was used for PDX’s treatment. Therapy response was monitored by sequential tumor volume measurements over time. ResultsOur analysis of available RNA and cisplatin IC50 data from HNSCC cell lines demonstrated that wild type HRAS levels are positively correlated with cisplatin resistance. To identify resistance signatures in wtHRASov tumors, we compared the TCGA HNSCC transcriptomes of HRAS-altered (HRASmut or wtHRASov) and HRAS- unaltered tumors. Approximately 6% of HNSCCs were overexpressing HRAS, and there was only partial overlap with the 6% of HRASmut tumors. Moreover, ERCC1 was found highly upregulated in HRAS altered group and especially among wtHRASov subcluster. To further study the resistance of wtHRASov tumors, we generated a cohort of HNSCC PDXs and acquired their mutational, expression and chemosensitivity profile. PDX tumors harboring a profile similar to wtHRASov TCGA cluster exhibited a strong chemoresistant squamous phenotype associated with high ERCC1 levels. Interestingly, these tumors were resensitized to cisplatin when subjected to cisplatin/tipifarnib combinatorial treatment. ConclusionsERCC1 expression is a well-established biomarker for cisplatin resistance. Our study demonstrates that wtHRASov tumours represent a distinctive entity that strongly express ERCC1 and can be resensitized to cisplatin by tipifarnib. Legal entity responsible for the studyThe authors. FundingKura Oncology. DisclosureT. Rampias: Research grant / Funding (institution): Kura Oncology Company. All other authors have declared no conflicts of interest.

TIPIFARNIB IN RELAPSED OR REFRACTORY ANGIOIMMUNOBLASTIC T‐CELL LYMPHOMA (AITL) AND CXCL12+ PERIPHERAL T‐CELL LYMPHOMA (PTCL): PRELIMINARY RESULTS FROM A PHASE 2 STUDY

Introduction: Tipifarnib is a potent and selective inhibitor of the enzyme farnesyltransferase (FT). CXCL12 is a chemokine that is essential for T cell homing to lymphoid organs and the bone marrow, and for the maintenance of immune cell progenitors. Tipifarnib has previously been shown to modulate the CXCL12 pathway and to drive clinical activity in CXCL12-expressing T cell lymphomas. Methods: This Phase 2 study (NCT02464228) is a multi-institutional, single-arm, open-label trial initially designed as a two-stage (11+7 pts) study to determine the efficacy, safety and biomarkers of tipifarnib in pts with relapsed/refractory (R/R) PTCL. Based on initial findings, the study was amended to include a cohort of AITL (n=12) and PTCL (n=12) with the CXCL12 rs2839695 A/A genotype (CXCL12+ cohort). Pts received tipifarnib 300 mg orally twice daily on days 1-21 of 28-day treatment cycles. The primary endpoint is overall response rate (ORR). Ancillary studies are ongoing to investigate the prognostic value of CXCL12 expression in pts who received standard of care treatment. Results: As of 20 February 2019, 43 PTCL pts (20 AITL, 21 PTCL-NOS, 1 ALK- ALCL, 1 gamma-delta TCL) have been treated with tipifarnib, 19 pts in stages 1 and 2, and 24 pts in the ongoing AITL histology and CXCL12 cohort. Median number of prior treatment regimens was 3; 19 pts had a prior stem cell transplant. All pts had at least 1 treatment-emergent adverse event (TEAE); 39 (90%) had at least 1 drug-related TEAE and 12 (28%) at least 1 drug related SAE. The most frequently observed drug-related TEAEs of Grade >3 occurring in >10% of pts were blood and lymphatic system disorders, including neutropenia (44%), thrombocytopenia (37%), leukopenia (28%), anemia (21%) and febrile neutropenia (21%). There have been 14 deaths on study; none were related to study drug. Of 18 evaluable pts enrolled in Stages 1 and 2 of the trial, 3 partial responses (PR), 2 of them in pts with AITL histology, and 4 best responses of stable disease (SD) were observed. In the AITL cohort (11 evaluable pts), a 45% ORR and 73% clinical benefit rate (CBR; 3 CR, 2 PR and 3 SD) was observed. In the CXCL12+ cohort (n=3 evaluable pts), 1 PR and 2 SD have been observed, with 4 pts pending cycle 2 response evaluation. CXCL12 expression correlated with favorable outcome to tipifarnib treatment. Pre-treatment high CXCL12 expression had 90% sensitivity and 93% specificity to identify pts who experienced CR/PR/SD on study in a preliminary analysis of 24 pts. The prognosis of CXCL12 was retrospectively investigated in 73 pts who received standard of care therapy (AITL N=50, PTCL NOS=23). A trend for poor prognosis (22 vs 40 months median OS from diagnosis, HR=1.8, p=0.09) was observed in the high CXCL12 subset using the cut-off point that predicted clinical benefit under tipifarnib therapy. Conclusion: Preliminary activity of tipifarnib was observed in PTCL pts, particularly in those with tumors of AITL histology and high CXCL12 expression and enrollment in the CXCL12+ cohort continues. Keywords: angioimmunoblastic T-cell lymphoma (AITL); peripheral T-cell lymphomas (PTCL). Disclosures: Witzig, T: Research Funding: Study Investigator for KO-TIP-002 (Kura Oncology). Sokol, L: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). Kim, W: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). Foss, F: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). Jacobsen, E: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). de la Cruz Vincente, F: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). Caballero, D: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). Advani, R: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). Roncero Vidal, J: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). Marin-Niebla, A: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). Rodriguez Izquierdo, A: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). de Ona Navarrete, R: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). Terol, M: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). Domingo-Domenech, E: Research Funding: Investigator for KO-TIP-002 (Kura Oncology Sponsored Clinical Study). Rodriguez, M: Research Funding: Kura Oncology. Piris, M: Research Funding: Kura Oncology. Bolognese, J: Consultant Advisory Role: Kura Oncology. Janes, M: Consultant Advisory Role: Kura Oncology. Burrows, F: Employment Leadership Position: Kura Oncology; Stock Ownership: Kura Oncology. Kessler, L: Employment Leadership Position: Kura Oncology; Stock Ownership: Kura Oncology. Mishra, V: Employment Leadership Position: Kura Oncology; Stock Ownership: Kura Oncology. Curry, R: Employment Leadership Position: Kura Oncology; Stock Ownership: Kura Oncology. Kurman, M: Employment Leadership Position: Kura Oncology; Stock Ownership: Kura Oncology. Scholz, C: Employment Leadership Position: Kura Oncology; Stock Ownership: Kura Oncology. Gualberto, A: Employment Leadership Position: Kura Oncology; Stock Ownership: Kura Oncology.

Pegilodecakin Combined with Anti-PD-1 Monoclonal Antibodies for Patients with Advanced Renal Cell Carcinoma (IVY): A Multicentre, Open-Label, Phase 1b Trial

Pegilodecakin Combined with Anti-PD-1 Monoclonal Antibodies for Patients with Advanced Renal Cell Carcinoma (IVY): A Multicentre, Open-Label, Phase 1b Trial

Crosstalk between the IGF1 and CXCL12 Pathways Defines Objective Responses to the Farnesyl Transferase Inhibitor Tipifarnib in AML and PTCL Patients

BackgroundCXCL12 is a chemokine that is essential for the maturation of myeloid and lymphoid cells. Tipifarnib is a potent and selective inhibitor of the enzyme farnesyltransferase (FT). Treatment with this agent may translate to durable responses in subsets of patients (pts) with acute myeloid leukemia (AML), chronic myelomonocytic leukemia (CMML) and peripheral T-cell lymphoma (PTCL) but its mechanism of action in these indications is poorly understood. We have previously reported that tipifarnib interferes with the CXCL12 pathway. Here we show that an interplay between the CXCL12 and IGF1 pathways may define those pts who may experience objective responses with tipifarnib monotherapy.MethodsGene expression profile (GEP) data generated using RNA-Seq and the Affymetrix U133A gene-chips of tumor samples from 129 pts enrolled into tipifarnib trials (CTEP-20, KO-TIP-002,KO-TIP-004, INT-17) were analyzed with respect to study outcomes and complemented with analyses of mRNA expression in data sets from the cBioportal for Cancer Genomics. Gene expression was further validated using RT-PCR assays. RNA-Seq and Whole Exome Sequencing were conducted using standard methodologies. Clinical trial information: NCT00027872, NCT02464228. NCT02807272, NCT00354146.ResultsIn order to improve our understanding of the molecular pathology of tumor CXCL12 overexpression, we investigated GEPs from 8,401 cancer pts in 25 studies available at cBioportal (TCGA, Provisional). Notably, we found a highly significant correlation in the expression of the IGF1 and CXCL12 genes in 19 of those studies. Intriguingly, the highest IGF1/CXCL12 correlations were observed in indications, including AML (ρ=0.698, p<0.001), in which activity of tipifarnib as monotherapy has been previously reported (AML, breast and urothelial cancer). Based on these results, we investigated the effect of IGF1/CXCL12 co-expression on pt outcome in tipifarnib studies. In previously untreated AML, 3 subsets of pts were identified with respect to bone marrow (BM) IGF1/CXCL12 expression: (1) high IGF1, high CXCL12 with predominantly hematological improvement or stable disease (SD) as best response, (2) intermediate IGF1, low CXCL12, with predominantly disease progression (PD), and (3) low IGF1, variable CXCL12, with 6 complete responses in 15 pts that were associated with CXCL12 expression (p=0.013), supporting the notion that CXCL12 pathway activation determines objective responses with tipifarnib while IGF1 mediates drug resistance. Barely detectable levels of IGF1 (and IGF2) were observed in the BMs of CMML pts in whom only 1 best response of PD was reported. In contrast, elevated levels of both CXCL12 and IGF1 were observed in PTCL pts responding to tipifarnib. Further investigation revealed that tumors of PTCL pts experiencing a partial response (PR) with tipifarnib expressed high levels of IGFBP7 (p=0.03), a natural inhibitor of the IGF1 receptor. Sequencing of the CXCL12 and IGF1 genes in PTCL samples revealed the presence of polymorphisms in non-responding pts: 8 pts, 7 carrying CXCL12 rs2839695 and 1 with a novel 3UTR variant, experienced a best response of PD. No pts with a best response of PR or SD carried 3UTR variants in CXCL12 (0% vs 80%, p=0.007). No pt with a best response of PR, 1 of 4 pts with SD and 6 of 10 pts with PD carried the IGFBP7 variant L11F (rs11573021) (16% PR/SD vs 60% PD, p=0.15)ConclusionsPre-treatment tumor CXCL12, IGF1 and IGFBP7 expression may enable the identification of pts susceptible to experience objective responses with tipifarnib monotherapy. These data may contribute to the understanding of the mechanism of action of FT inhibitors. DisclosuresGualberto:Kura Oncology: Employment, Equity Ownership. Mishra:Kura Oncology: Employment, Equity Ownership. Janes:Wellspring Biosciences: Employment, Equity Ownership. Kessler:Kura Oncology: Employment, Equity Ownership.

Tipifarnib in Relapsed or Refractory Angioimmunoblastic T-Cell Lymphoma (AITL) and CXCL12+ Peripheral T-Cell Lymphoma (PTCL): Preliminary Results from an Open-Label, Phase 2 Study

Tipifarnib in Relapsed or Refractory Angioimmunoblastic T-Cell Lymphoma (AITL) and CXCL12+ Peripheral T-Cell Lymphoma (PTCL): Preliminary Results from an Open-Label, Phase 2 Study

Early Results from a Biomarker-Directed Phase 2 Trial of Sy-1425 in Combination with Azacitidine or Daratumumab in Non-APL Acute Myeloid Leukemia (AML) and Myelodysplastic Syndrome (MDS)

Early Results from a Biomarker-Directed Phase 2 Trial of Sy-1425 in Combination with Azacitidine or Daratumumab in Non-APL Acute Myeloid Leukemia (AML) and Myelodysplastic Syndrome (MDS)

Imetelstat Treatment Leads to Durable Transfusion Independence (TI) in RBC Transfusion-Dependent (TD), Non-Del(5q) Lower Risk MDS Relapsed/Refractory to Erythropoiesis-Stimulating Agent (ESA) Who Are Lenalidomide (LEN) and HMA Naive

BACKGROUND:Patients with TD lower-risk (LR)-MDS relapsed or refractory to ESA have limited treatment options. Imetelstat is a first-in-class telomerase inhibitor that targets cells with short telomere lengths and active telomerase, characteristics observed in some MDS patients. IMerge is an ongoing global study of imetelstat in RBC TD patients with LR-MDS (IPSS Low or Int-1). In the first 32 patients enrolled, 8-week TI rate was 34%, with 24-week TI of 16%, and HI-E of 59%. The most frequently reported adverse events were reversible grade ≥3 cytopenias (Fenaux et al EHA 2018 Abstr S1157). Higher response rates were observed in patients (n=13) who were LEN and HMA naïve without del(5q). We report here results in an additional 25 LEN and HMA naïve patients without del(5q), with longer term follow-up of the 13 initial patients meeting the same criteria.METHODS:IMerge is a phase 2/3 trial (NCT02598661) that includes LR-MDS patients with a high transfusion burden (≥4 units / 8 weeks) who are relapsed/refractory to ESA or have sEPO >500 mU/mL. The additional 25 were required to be LEN and HMA naïve and lack del(5q). Imetelstat 7.5 mg/kg was administered IV every 4 weeks. In addition to the key endpoints noted above, secondary endpoints include safety, time to and duration of TI. Biomarkers are also being explored, including telomerase activity, hTERT, telomere length, and genetic mutations.RESULTS:Overall, for the 38 LEN/HMA naïve and non-del(5q) patients, median age was 71.5 years and 66% were men. 63% of patients were IPSS Low and 37% Int-1. Median prior RBC transfusion burden was 8.0 (range 4-14) U, and 71% had WHO 2008 RARS or RCMD-RS. 9/37 (24%) patients with evaluable sEPO levels had baseline level >500 mU/mL.As of July 2018, with a median follow-up of 25.8 months for the initial 13 patients, and 5.2 months for the 25 recently included patients, the 8-week RBC-TI rate was 37% (14/38). Durability of 24-week TI responses was demonstrated, with a median duration of 10 months and the longest ongoing response now >2 years. Among the patients achieving durable TI, all showed a Hb rise of ≥3.0 g/dL compared to baseline during the transfusion-free interval. Response rates were similar in RARS/RCMD-RS (33% [9/27]) and other patients (27% [3/11]), and those with baseline EPO levels >500 mU/mL (33% [3/9]) and ≤500 mU/mL (32% [9/28]).Reversible grade ≥3 neutropenia and thrombocytopenia were each reported in 58% of the patients. Liver function test (LFT) elevations were mostly grade 1/2. Reversible grade 3 LFTelevations were observed in 3 (8%) patients on study. An independent Hepatic Review Committee deemed the observed LFT elevations were not imetelstat-related hepatic toxicities.SUMMARY / CONCLUSIONS:In this cohort of 38 non-del(5q) LR-MDS patients with a high RBC transfusion burden who were ESA relapsed/refractory and naïve to LEN/HMA, single-agent imetelstat yielded a TI rate of 37%, with a median duration of 10 months and limited side effects. Durable responses were characterized by transfusion independence >24 weeks and accompanied by Hb rise. Updated data will be presented. DisclosuresSteensma:Takeda: Consultancy; Syros: Research Funding; Otsuka: Membership on an entity's Board of Directors or advisory committees; Onconova: Consultancy; Novartis: Membership on an entity's Board of Directors or advisory committees; Kura: Research Funding; Janssen: Consultancy, Research Funding; H3 Biosciences: Research Funding; Celgene: Research Funding; Amphivena: Membership on an entity's Board of Directors or advisory committees; Acceleron: Consultancy. Platzbecker:Celgene: Research Funding. Van Eygen:Janssen: Consultancy, Research Funding; Roche: Research Funding; Amgen: Research Funding. Raza:Kura Oncology: Research Funding; Onconova: Research Funding, Speakers Bureau; Celgene: Research Funding; Novartis: Speakers Bureau; Geoptix: Speakers Bureau; Janssen: Research Funding; Syros: Research Funding. Santini:Amgen: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria; AbbVie: Membership on an entity's Board of Directors or advisory committees; Otsuka: Consultancy; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Research Funding. Germing:Celgene: Honoraria, Research Funding; Janssen: Honoraria; Novartis: Honoraria, Research Funding. Font:Celgene: Membership on an entity's Board of Directors or advisory committees. Samarina:Janssen: Research Funding. Díez-Campelo:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Bussolari:Janssen: Employment, Equity Ownership. Sherman:Janssen: Employment, Equity Ownership. Sun:Janssen: Employment, Equity Ownership. Varsos:Janssen: Employment, Equity Ownership. Rose:Janssen: Employment, Equity Ownership. Fenaux:Roche: Honoraria; Otsuka: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding.