ALBERT

Description: Background: Cancer patients (pts) who receive chemotherapy and/or radiation therapy for their primary tumor are at risk for developing therapy-related myeloid neoplasms (t-MN). Estimates of t-MN prevalence are mainly derived from retrospective series from hematology departments: they account for 10 to 20% of all AML cases. However this condition is frequently diagnosed in daily practice in comprehensive cancer centers (CCC). This suspected higher frequency might be due to optimized follow-up protocols and improved survival outcomes after tumor remission. The aim of this study was to assess clinical factors associated with t-MN in 2 French CCC focusing on delay of onset, survival, cytogenetically defined prognosis, treatment received for primary tumor and myeloid disease presentation. Methods: We conducted a retrospective study of cancer pts who developed t-MN seen at Institut Gustave Roussy, Villejuif, France and Institut Curie, Saint-Cloud, France between 2004 and November 2014. As defined in the current 2008 WHO classification, t-MN includes therapy-related acute myeloid leukemia (t-AML), myelodysplastic syndrome (t-MDS) and myelodysplastic/myeloproliferative neoplasms (t-MDS/MPN). The study inclusion criteria were development of t-MN after chemotherapy and/or radiation therapy for any primary tumor. Results: 116 patients were retrieved from our records. 86 patients were women (74%) and the median age at t-MN diagnosis was 65 years (range, 25-91 years). The distribution of primary malignancies by site was as follows: breast cancer 46 pts, hematologic malignancy (lymphoma and myeloma) 24 pts, gynecologic cancer 14 pts, head and neck cancer 8 pts, urologic cancer 6 pts, gastrointestinal cancer 4 pts, miscellaneous (sarcoma, neurooncology, neuroendocrinology cancer) 14 pts. The median interval between primary cancer and t-MN was 60 months (range, 12-324). At the time of t-MN diagnosis, 69 (59%) had t-AML, 46 (40%) had t-MDS and 1 (1%) had t-MDS/MPN. Of note, among t-AML pts 15 (13%) had AML with recurrent genetic abnormalities and 14 had AML (12%) with MDS-related changes. Median survival from the diagnosis of t-MN was 6.5 months (5y OS was below 20%). Adverse risk karyotypes were prominent (63 pts, 59%) followed by intermediate risk (32 pts, 30%). Of note 12 pts (10%) had favorable risk karyotype. The impact of karyotype on survival was crucial: median survival was 60 months for favorable risk pts, 14 months for intermediate risk pts and only 6 months for adverse risk karyotypes. 26 pts (22%) were treated by radiation therapy alone. Treatment modality (radiation therapy alone, chemotherapy alone or combined treatment) did not affect survival or delay of onset. Of note, when we isolated pts treated by alkylating agents without topoisomerase inhibitors from those treated by topoisomerase inhibitors without alkylating agents we found that the disease presentation did not differ (same proportion of t-AML vs. t-MDS in each group), an observation in contrast with the classical description of post-alkylating agent t-MDS vs. post- topoisomerase inhibitor t-AML. Conclusion: We report a heterogeneous cohort of 116 pts with numerous primary tumors and treatment protocols. Prominent adverse risk karyotypes are in line with a dismal survival yet favorable risk karyotypes are not uncommon and remain associated with a relatively good prognosis. Disclosures No relevant conflicts of interest to declare.

Description: The previous studies assessing the relationship of cytogenetic abnormalities to JAK2 status have not shown any significant associations, although numbers have generally been too small to make a definitive comment. We therefore assessed the JAK2 V617F mutation status of 337 patients from 39 centers (175 males, 161 females; median age at time of study 71 years old, range 32–98). Patients were classified as follows: 100 with typical MDS, 10 with 5q- syndrome, 17 with AREB-2, 2 with RARS, 13 with RARS-T, 23 with MPD/MDS, 12 with CMML, 142 with typical MPDs, 5 with hypereosinophilic syndrome (HES), 7 with AML with multi-lineage dysplasia from Ph- MPD, 10 with aCML Ph- or MPD/MDS-u and 25 with typical CML Ph+. Bone marrow or blood derived genomic DNA was screened for the JAK2 mutation. The JAK2 V617F mutation was found in 109/337 pts (32%): typical MPD-Ph− (47%) cases, MDS (4.5%), 5q- syndrome (60%), AREB-2 (64%), CMML (42%), MDS/MPD (36%). A clonal cytogenetic abnormality was detected by R-banding in 159/337 cases (47%). The JAK2 mutation was associated with a chromosomal abnormality in 81/159 cases (51%). The most common chromosome abnormality associated with JAK2 mutation was the gain of chromosome 9 (n= 22, Associated with JAK2 mutation: 19/22 cases 86%). The second most common abnormality was partial deletion of 20q (n=30, Associated with JAK2 mutation: 19/30 cases 63%). The partial or complete loss of chromosome 7 (n=16, Associated with JAK2 mutation: 6/11), deletion of 5q- (n=10, Associated with JAK2 mutation: 6/10), gain of chromosome 8 (n=11, Associated with JAK2 mutation: 7/11), partial deletion of 11q (n=8, Associated with JAK2 mutation: 5/8), partial deletion of 12p (n=6 Associated with JAK2 mutation 4/6), partial deletion of 13q (n=5, Associated with JAK2 mutation: 4/5). Patients with trisomy 9 and JAK2 mutation were classified as follows : polycytemia vera (PV) n=4 (100% JAK2 mutated), essential thrombocytemia (ET) n=3 (100% JAK2 mutated), idiopathic myelofibrosis (IMF), n=2 (100% JAK2 mutated), MPD/MDS, n=3 (67% JAK2 mutated), secondary AML post MDS, n=1 (JAK2 mutated), atypical MPD, n=6 (100% JAK2 mutated), MMCL, n=1(JAK2 mutated). The V617 mutation was not found in the case of de novo AML, and 2 typical MDS cases. 9 males, 10 females, the median age: 68 years old, range 40–98 years old, median white cell count (WCC) 11 G/l, range 2.4–50.7 G/l (13/19 pts〉 10G/l), median hemoglobin 13.5 g/dl, range 9–20.2 g/dl (5/19 pts〉 17g/dl), median platelet count 667G/l range 9–1769 G/l (9/19 pts〉 500 G/l). The BCR/ABL transcript (multiplex PCR) was not detected in all of these cases. In this study the gain of chromosome 9 associated with JAK2 V617F mutation was the most frequent chromosome abnormality (100%) observed in typical MPDs and atypical syndrome such as MDS/MPD. In summary, previous studies assessing the relationship of cytogenetic abnormalies to JAK2 status did not show any significant association (ref). The del(20q), del(13q), trisomy 8 and del(5q) are known to be recurring non-specific cytogenetic abnormalities, and some of them are also detectable in patients with JAK2 mutation positive or negative. We describe here a significant association the JAK2 V617F mutation and trisomy of chromosome 9 that was detected in a cohort of patients with gain of chromosome 9. Clearly, in addition to PV, IMF, and ET these associations were found in other disease entities, high frequency in the case of atypical MPDs particularly in the case of aCML. Previously, Campbell et al. reported 10 patients with a trisomy 9, in typical MPDs, all of them were V617F+. A longer follow-up and morphological diagnosis is however necessary to determine the prognostic signification of JAK2 mutation and +9 in the cases of classic myeloproliferative syndromes and atypical syndrome such as MDS/MPD overlap syndrome.

Description: Somatic point mutations in the active site of IDH (isocitrate dehydrogenase) 1 and IDH2 genes are observed in acute myeloid leukemia (AML). These mutations lead to the production and accumulation of R-2-hydroxyglutarate (2-HG) in the tumor blast cells as well as in the plasma of patients. High levels of 2-HG have been shown to inhibit alpha-ketoglutarate-dependent dioxygenases, including epigenetic regulators (i.e. histone or DNA demethylases), resulting in altered cellular differentiation. Ex vivo experiments in primary cells from AML IDH2 mutant patients have demonstrated that IDH2 mutant inhibitors are able to revert this phenotype. In order to test the biological activity of AG-221, an oral, reversible and selective inhibitor of mutated IDH2 currently in phase I trials, we developed primary human AML xenograft models. Primary blast cells from 3 AML patients with normal karyotype (n=3), NPM1 mutation (n=3) and FLT3ITD (n=1) were injected into immunodeficient NOD SCID IL2R gamma null (NSG) mice by intrafemoral injection after sub-lethal irradiation. Medullar and peripheral tumoral engraftment was monitored by flow cytometry (using species-specific antibodies) and serum 2-HG measurements. Engraftment of IDH2-R140Q human blast cells was not lethal, but these AML cells persisted over time. Twelve months after injection, IDH2-R140Q blast cell-engrafted mice were randomized into two groups, for treatment with AG-221 (30 mpk) or vehicle (0.5% methylcellulose / 0.2% Tween 80, in water) (n=10 mice; 5 mice per condition). Treatments were administered by oral gavage for 38 days twice per day (BID). Peripheral blood was collected at multiple time points for the determination of pharmacokinetics (PK) and pharmacodynamics (PD), and the assessment of the differentiation effects by AG-221 on human tumor cells. PK/PD analyses showed good plasma exposure of AG-221 and reduction of 2-HG. Furthermore, AG-221 administration also induced a burst of proliferation of human blasts followed by myeloid differentiation starting at day 20 in peripheral blood as measured by the expression of CD11b, CD14, CD15, CD24 and cell morphology. No effects on proliferation or differentiation were seen in the absence of AG-221 administration. Histological analyses of hematopoietic organs in treated animals showed a decrease of infiltrating human cells, as well as obvious morphological changes in the human cell population in AG-221-treated animals compared with vehicle-treated animals. Flow cytometry confirmed the differentiation of the human cells in the spleen and bone marrow of the AG-221-treated mice. Furthermore, cells undergoing differentiation retained the R140Q mutation, demonstrating the differentiating effect of the compound. In conclusion, AG-221 reduced serum 2-HG levels and triggered differentiation of leukemic blast cells engrafted in NSG mice. These results are consistent with what has been observed clinically in IDH2 mutant AML patients treated with AG-221 in a phase I dose escalation trial. Disclosures Quivoron: Institut National de la Santé Et de la Recherche Médicale (INSERM): Grant Other; Association Laurette Fugain: Grant, Grant Other; Institut National du Cancer (INCa): Grant, Grant Other; Association pour la recherche contre le Cancer (ARC): Grant, Grant Other; AGIOS: Grant Other. David:Institut National de la Santé Et de la Recherche Médicale (INSERM): Grant Other; Institut National du Cancer (INCa): Grant, Grant Other; Association pour la Recherche contre le Cancer (ARC): Grant, Grant Other; Association Laurette Fugain: Grant, Grant Other; AGIOS: Grant Other. Straley:Agios Pharmaceuticals: Employment, Stockholder Other. Travins:Agios Pharmaceuticals: Employment, Stockholder Other. Kim:Agios Pharmaceuticals: Employment, Stockholder Other. Chen:Agios Pharmaceuticals: Employment, Stockholder Other. Zhu:Agios Pharmaceuticals: Employment, Stockholder Other. Bawa:AGIOS: Grant Other. Bernard:Institut National de la Santé Et de la Recherche Médicale (INSERM): Grant Other; Association Laurette Fugain: Grant, Grant Other; Institut National du Cancer (INCa): Grant, Grant Other; Ligue Nationale contre le cancer (LNCC): Grant, Grant Other; AGIOS: Grant Other. Yang:Agios Pharmaceuticals: Employment, Stockholder Other. Agresta:Agios Pharmaceuticals: Employment, Stockholder Other. de Botton:AGIOS: Grant Other. Yen:Agios: Employment. Penard-Lacronique:Institut National de la Santé Et de la Recherche Médicale (INSERM): Grant Other; Association Laurette Fugain: Grant, Grant Other; Institut National du Cancer (INCa): Grant, Grant Other; Association pour la recherche contre le Cancer (ARC): Grant, Grant Other; AGIOS: Grant Other.

Description: Background Myelodysplastic syndromes (MDS) are pre-leukemic hematopoietic stem cell disorders. Among them, 10 to 20% occur after cytotoxic treatment for prior cancer by chemotherapy and/or radiotherapy, and are called “therapy-related MDS” (t-MDS). However, only a minimal proportion of patients exposed to anticancer drugs or radiation develop secondary MDS, suggesting that a genetic component takes place in individual susceptibility. Genetic determinants of susceptibility to t-MDS are unknown. The aim of this study was to identify such genetic markers. Patients and Methods A prospective cohort of 59 MDS patients (39 de novo MDS, 20 t-MDS) was studied. Using a custom-made SNP chip, we genotyped a total of 384 single nucleotide polymorphisms (SNP) selected among genes involved in DNA repair, drug metabolism and transport, signal transduction and oncogenesis. We analysed the associations existing between each genotype and several clinical and pathological features (therapy-related character, adverse cytogenetic findings, IPSS score, acute leukaemia stage), using Benjamini-Hochberg correction for multiple testing. Results Two non-synonymous SNPs present in the methylguanine methyltransferase (MGMT) gene and in complete linkage disequilibrium, were significantly associated with t-MDS: rs2308321 and rs2308327, with a raw p value of 7.4×10-5 and a corrected p value of 0.014. Other associations tested between clinical and cytogenetic features and SNP chip gene variants were not significant. An independent validation cohort was separately constituted of 43 patients (24 de novo MDS, 19 t-MDS) and the two MGMT SNPs were genotyped by pyrosequencing; this allowed us to confirm a significant association between the variant allele of MGMT and the therapy-related character of MDS (p=0.038). Discussion MGMT encodes a protein involved in direct DNA repair by removing alkyl adducts from guanine at oxygen-6 position. The two SNPs identified both induce a change in amino acid sequence of the protein (rs2308321: Ile143Val, rs2308327: Lys178Arg) and may therefore impact the functional capacity of the enzyme. A reduced activity of MGMT variant protein as compared to wild-type would explain an increased sensitivity to alkylating agents and a higher risk for secondary tumour development. Nevertheless, the impact of MGMT variants on protein expression and activity was not demonstrated in functional studies conducted previously. Conclusion This gene-oriented susceptibility study allowed to detect, in both an identification and a validation cohort, a significant association between a variant allele of the DNA repair gene MGMT and the therapy-related character of MDS. We thus identified a putative marker of the risk to develop MDS after cancer treatment. This observation may lead to special consideration of the patients at risk when they are prescribed chemotherapy or radiotherapy and to the choice of treatment regimen producing minimal DNA damage. Disclosures: Etienne: Novartis: Consultancy, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Ariad Pharmaceuticals: Membership on an entity’s Board of Directors or advisory committees; Pfizer: Membership on an entity’s Board of Directors or advisory committees; Bristol Myers Squibb: Consultancy, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau.

Description: Background: The oncogenic BRAF V600E mutation activates the MAPK signaling pathway resulting in cell growth and survival of tumor cells carrying the mutation. Targeting BRAF has shown its efficacy in metastatic melanomas. BRAF V600E mutation has been described in multiple myeloma (MM), with an incidence of 4-10% in previous reports. We report here the incidence of BRAF mutations in a series of MM patients treated at our center. Methods: From February 2012 to March 2016, 94 MM patients were tested for BRAF mutations. Eighty-one samples came from patients with relapsed/refractory MM (R/R MM) and 13 samples from newly diagnosed patients. Eighty-eight samples were collected from bone marrow aspirates, 3 from extramedullary plasmacytoma biopsies, 1 from pleural effusion, and 2 from peripheral blood. Targeted sequencing for BRAF mutations using Sanger direct sequencing or targeted next generation sequencing were performed on all samples after CD138 cell (after 2015). In addition, NGS was performed for 2 patients. From 2012 to 2015, we used material obtained from scraping bone marrow smears with 〉 20% plasma cells. Since 2015, we began using immunomagnetic cell-sorting based on the CD138 cell surface marker (Stem Cells®). Results: BRAF mutations were detected in 8 samples out of the 84 that could have been screened (9.5%). When considering only the relapsed/refractory population, the incidence of BRAF mutations was 10.8%. One sample had the inactivating D594N BRAF mutation and the other 7 had the V600E BRAF mutation. The 8 mutated patients had relapsed/refractory MM at the time of analysis. Of note, 5 out of the 8 mutated patients (62.5%) had an IgA MM. Seventy-six samples had no BRAF mutation detectable. Ten samples were not tested because of the small percentage of MM cells on the bone marrow smears. The failure rate was 16% with the scraping technique and 3.4% with the sorting cell technique. Five out of 7 patients harboring the V600E BRAF mutation were treated with a BRAF inhibitor in different clinical trials. One mutated patient could not be treated due to exclusion criteria related to an underlying condition (terminal renal failure requiring chronic hemodialysis) and one patient received allogeneic stem-cell transplantation at relapse. No BRAF mutation was detected in the 13 newly diagnosed patients. Conclusion: Our results show that BRAF screening is feasible in routine practice and can help orienting therapy in relapsed/refractory MM patients. The incidence of 9.5% that we found in our series compares favorably with previously published results, and we observed a slightly increased incidence of 10.8% in the R/R population. The cell sorting technique seems to be more effective than the scraping technique for MM sample DNA acquisition and BRAF mutation screening. Results of BRAF inhibitors therapy in MM are eagerly awaited. Disclosures Lacroix: sanofi: Research Funding; qiagen: Membership on an entity's Board of Directors or advisory committees; roche: Membership on an entity's Board of Directors or advisory committees; astrazeneca: Membership on an entity's Board of Directors or advisory committees. Michot:Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees. Ribrag:ArgenX: Research Funding; Esai: Membership on an entity's Board of Directors or advisory committees; Infinity: Membership on an entity's Board of Directors or advisory committees; Pharmamar: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; NanoString: Membership on an entity's Board of Directors or advisory committees.

Description: Therapy-related acute myeloid leukemia/myelodysplastic syndrome (t-AML/MDS) arise after cytotoxic chemotherapy and/or radiotherapy administered for a prior neoplasm and have a dismal outcome (median survival of 8 months in the largest series published including 306 patients (pts), Smith, Blood 2003). Recent registry data suggested a continued increase in survival in AML (Derolf, Blood 2009) and we wondered whether this was also observed in the setting of t-AML/ MDS. All pts with a t-AML/MDS diagnosed and/or treated for their prior neoplasm at Gustave Roussy Cancer Center between July 1986 and 2016 were included in this retrospective study. Data regarding pts' demographics, primary diagnosis and treatment, latency time, cytogenetic, treatment and outcome were collected. The diagnosis of t-AML/MDS was based on the WHO 2016 classification. t-AML were classified based on cytogenetic results as favorable, intermediate and adverse according to international classification, t-MDS based on IPSS score as favorable (Low, Int-1) and adverse (Int-2 and High). 428 pts were analyzed. The median age at diagnosis of t-AML/MDS was 56.4 years with a female predominance (60%). 224/428 (52.3%) pts had t-AML, 204/428 (47.7%) t-MDS. The most common primary malignancies were breast cancer (24%), non-Hodgkin lymphoma (15%), Hodgkin lymphoma (HL) (9%) and ovarian cancer (9%). Occurrence of t-AML/MDS following HL represented 26.6% of t-AML/MDS cases between 1986-96 comparing to 4 % between 2006-16 whereas breast cancer rose from 16% to 45%. Prior treatments included chemotherapy alone in 137/428 pts (32%), radiotherapy alone in 61 pts (14%) and both in 230 pts (54%). At diagnosis of t-AML/MDS, 295 pts (69%) were in complete remission (CR) of their prior neoplasm, 29 (7%) had a stable and 104 (24%) a progressive disease. Median interval between primary cancer and t-AML/MDS was 5 years (4.3 and 5.7 years for t-AML and t-MDS respectively, (p=0.03)). Furthermore, delay to develop t-AML/MDS after radiotherapy alone was longer compare to chemotherapy or both (6.1, 5.1 and 4.3 years, respectively (p=0.0087)). In the t-AML subgroup, 47% of pts presented unfavorable cytogenetic (including complex karyotype (20%) and 11q23 abnormalities (16.9%)), 26% intermediate and 26% favorable cytogenetic (core binding factor mutations (12.7%), t(15;17) (13.3%)). In the t-MDS subgroup, 78% of pts were considered adverse; complex karyotype, chromosome 7 and 5 abnormalities were found in 40.8%, 46.7% and 28.9% respectively. Pts received intensive chemotherapy (including 41 allografts), low dose chemotherapy (including 74 treatments with hypomethylating agents) and best supportive care in 42%, 24% and 34% respectively. The median overall survival (OS) was 10.6 months and the 5-year survival was 19.1% (Figure 1A). The 5-year OS of patients in CR of their prior neoplasm was 25.5% compared to 3.65 and 0% for pts with progressive and stable disease, respectively (p

Description: Key Points An increase in the classical monocyte subset to 〉94% of total monocytes discriminates CMML from other monocytoses with high specificity. This characteristic increase in classical monocytes disappears in CMML patients who respond to hypomethylating agents.

Description: Key Points Identification of SRP54 mutations in congenital neutropenia. SRP54 mutations induce ER stress and autophagy associated with apoptosis.

Description: Introduction Clonal selection is one of the mechanisms leading to therapy-related myeloid neoplasms (TRMN). A preexisting somatic mutation in hematopoietic stem cell (defined as clonal hematopoiesis [CH]) emerges under pressure of chemotherapy or radiotherapy, leading to TRMN development. Most of these mutations belong to the DNA damage response (DDR) pathway as TP53 or PPM1D mutations and are known to confer a dismal prognosis. Recently authorized for the treatment of ovarian cancers (OC), the poly (ADP-ribose) polymerase inhibitors (PARPi) represent a promising targeted therapy. However, by inducing DNA damage and altering DNA repair process, PARP inhibition could represent a challenge for the genetic stability of the healthy tissues. Thus, we assessed the effect of PARP inhibition on the development of CH and TRMN after PARPi treatment for OC (TRMN-PARPi) in combination with chemotherapies. Methods Firstly, we performed a targeted 77 genes mutational analysis using Next Generation Sequencing (NGS) in 13 patients exposed to PARPi without TRMN. Secondly, we retrospectively identified, with the help of the UNIHEM group of Unicancer, 17 patients who experienced TRMN-PARPi. Clinical, biological and survival data were collected and compared to 23 OC patients with TRMN not treated with PARPi (Gustave Roussy institutional database). Lastly, NGS was performed for 3 patients with TRMN-PARPi with sequential sampling. Patient's samples were obtained with informed consent. Results Thirteen OC patients during maintenance treatment with PARPi without TRMN were explored by NGS. Median age at NGS was 64.5 years old (yo) (40.5-75.3). 4/13 (31%) patients harbored BRCA1/2 germline mutation. Time between OC diagnosis and NGS was 4.3 y (1-11.6). The median number of chemotherapy line at PARPi initiation was 2 (1-3). 7 received Olaparib, 5 Niraparib and 1 Rucaparib. The median duration of PARPi treatment before NGS was 4.7 months (1.1-25.1). 12/13 patients experienced hematological toxicities during the PARPi treatment. CH was found in 10/13 (77%) patients (Figure 1a), including mutations of DDR genes in 8/10 (80%). 6/8 (75%) patients had 2 or more gene mutations. Next we identified 17 cases of TRMN occurring during or after PARPi administration for OC (6/17 [35%] t-AML and 11/17 [65%] t-MDS). 12/17 (71%) patients had BRCA germline mutations (7 BRCA1 and 5 BRCA2). All received Olaparib with a median dose of 600mg/d (400-1200). Median duration of Olaparib treatment was 1.7 years (0.2-4.6). TRMN-PARPi were described 1.4 months (0-10.9) after the end of PARPi administration. We compared these patients to a cohort of TRMN post OC not treated by PARPi. Number of therapy lines for OC, time between TRMN and OC diagnosis, median age at TRMN, were, for TRMN-PARPi, 2 (1-8), 5.9 y (0.9-20.8), 64.4 yo (46-74); respectively, compared to 3 (1-8), 4.9 y (1.7-36.9), 59.3 yo (35.7-85.7); (p=ns). TRMN-PARPi cytogenetic was unfavorable for 16/17 (94%) (including 11/17 [65%] complex karyotype) compared to 16/23 (70%) (11/23 [48%] complex karyotype). C Median survival was significantly lower in the TRMN-PARPi group 3.9 months 95%CI [2.0-9.7] and 6.1 months 95%CI [4.1-15.8] respectively, p=0.046, Fig 1b). However, median survival from OC diagnosis was not different between the two groups 6.2 y 95%CI [5.6-NA] for TRMN-PARPi vs 5.6 y 95%CI [5.0-11.6]. NGS was available for 8/17 TRMN-PARPi and revealed mutations in DDR genes in 7/8 patients (6 patients with TP53 mutation, 2 with PPM1D mutation). For 3 patients, we had samples from OC stage, before PARPi administration. We found that mutations from TRMN stage were present at lower frequency, confirming clonal selection by PARPi treatment (Figure 1c). Conclusions Here we described, for the first time, a cohort of TRMN patients previously treated with PARPi for an OC. Intriguingly, most of these TRMN occurred with a short latency at the end of PARPi treatment, with unfavorable cytogenetic and very short OS. Moreover, we found a very high percentage of CH involved in the DDR pathway (62%) in patients under PARPi treatment without TRMN suggesting a potential clonal selection which could lead ultimately to TRMN. PARPi are now indicated in 1rst line high grade OC regardless of BRCA status, which should expand indications. Benefit for OC patients is not questionable; however, caution will be warranted for patients with CH before PARPi treatment, especially implicating DDR mutations. Disclosures Etienne: Incyte: Consultancy, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau.