show significant differences of primary outcomes between G and TC in any subgroup except for TP53. Patients with identified baseline TP53 mutations did worse on G vs TC while those without identified TP53 mutations had a more favorable outcome on G vs TC. Both treatment arms showed overall similar safety profiles with slightly higher but not significant serious AEs incidence (81% vs 75.5%) and Grade  3 AEs (91.5% vs 87.5%) on G vs TC respectively. There was no difference in AEs leading to death (28.7% for G vs 29.8% for TC). Summary/Conclusion: The trial did not achieve its primary endpoints of statistically significant superiority of G vs TC for CR or OS. However due to the large sample size and narrow 95% CI for OS difference, the trial suggests that G is an active drug with an overall similar efficacy and safety profiles to standard therapy. Potential benefit of G vs TC was observed in patients who were able to receive adequate treatment (>3 cycles), and those who achieved any CR. The significance of TP53 mutations needs to be further explored.

Background Chronic myeloid leukemia (CML) diagnosed during pregnancy is a rare situation with no standard treatment schemes. If a pregnancy is prolonged weighting the risks/benefits of therapy or observation without therapy is a complicated task. If a pregnancy is terminated a possibility of a further childbirth has to be judged. The course of the disease, treatment options and possible outcomes need to be known in these patients (pts) in the era of tyrosine kinase inhibitors (TKIs). Aim To describe pregnancy outcomes, therapy and follow-up in women with CML diagnosed during pregnancy in the era of TKIs Methods We made a search in the databases of pregnancy cases in CML pts after 2003 year, since the first TKI imatinib became available. The data were obtained from observational studies: CML pregnancy registries of Russian hematology society and ELN. Clinical and demographic characteristics of pts, therapy, monitoring, pregnancy outcomes and follow-up were analyzed. Results. We found that 48 of 199 women with CML and pregnancy were diagnosed as having CML during pregnancy in years 2006-2018. Median (Me) age at CML diagnosis was 26 years (range 19-39). All pts had a chronic phase of CML. Sokal score was low in 34(71%), intermediate in 9(19%) high in 4(8%) and not known in 1(2%) pt. CML was diagnosed during 1st, 2ndand 3rd trimester of pregnancy in 26(54%), 11(23%) and 11(23%) females, respectively. Elective abortion was done in 14 (29%) pts, 1(2%) pt had a miscarriage. All 15 pts started TKI therapy shortly after delivery. Me observation time after labour was 52 months (range 4-139). Imatinib (IM) and nilotinib (NIL) were used as 1st line therapy in 14 and 1 pt accordingly. Five pts were switched from IM to a second line TKI due to resistance in 3 pts and to physician choice in 2 pts. Deep molecular response (DMR or BCR-ABL≤0,01% IS) and major molecular response (MMR or BCR-ABL≤0,1% IS) was achieved in 6 and 5 pts. No molecular response 2 (MR2 or BCR-ABL≤1%) was reported in 4 pts with the follow-up of 24-184 months. One pt died due to CML progression in BC (resistant to IM, T315I mutation, relapsed after allogenic bone marrow transplant (BMT), pre ponatinib availability). Pregnancy was carried out in 33(71%) pts: in 11 of 26 pts with CML diagnosed at 1st trimester and in all 22 pts diagnosed at 2nd-3rd trimester. Pregnancy ended in labour in 32 pts while in 1 pt pregnancy was ongoing pregnancy (week 26th) at the time of evaluation. No therapy for whole pregnancy was in 14 pts: 1, 5 and 8 of them were diagnosed in 1st, 2nd and 3rd trimester accordingly. Therapy during pregnancy was started in 19 pts: 10, 6 and 3 pts with CML diagnosed in 1st, 2nd and 3rd trimester accordingly. Five pts got interferon (IFN) in 1st trimester and 3 of 5 were switched to IM in 2nd-3rd trimester. Four pts got hydroxyurea (HU) for 5-7 days in 1st-2nd trimester prior to any other therapy. Fourteen pts with no therapy in 1st trimester started therapy at late pregnancy: IM since 2nd-3rd trimester in 10 pts, HU in 3rd trimester in 1 pt. A total of 13 pts got IM with Me time of IM start at 18 weeks (range 16-35). Me time of observation after delivery was 52 months (range 4-139). Me time of delay in TKI administration after diagnosis was 7 weeks (range 1-51) and in total 12(36%) of 33 pts got IFN or HU before TKI. TKIs used as 1st line were as follows: IM, dasatinib and NIL in 30, 1 and 1 pts accordingly. Nine pts were further switched from IM to TKI2 as 2nd line due to resistance/suboptimal response. DMR and MMR was achieved in 11 and 17 pts accordingly, MR2 in 5 pts, no MR2 in 1 pt with short follow-up (4 months), 4 pts were too early to evaluate. Two pts were resistant to 2 lines of TKIs and died from disease progression; one of them had a BMT failure and 1 pt was non-compliant. Thirty three children were born (one twins): 17 boys and 16 girls, no births defects were observed. Seven newborns had a low birth weight (<2500g): 6 of them were exposed to IM at late pregnancy and 3 were born preterm at week 35-37. Follow-up of the children was uneventful. Eleven pts later had 13 pregnancies which ended in childbirth within Me 5 years (1-9 years) Conclusion CML may be diagnosed at any pregnancy stage and pregnancy termination/prolongation should be judged individually. A normal childbirth may take place including cases with use of IM at late pregnancy. It is reasonable to adjust therapy options to pregnancy trimester and to avoid potential teratogenic drugs at 1st trimester. A careful follow-up and timely monitoring of these cases is needed. Disclosures Chelysheva: Fusion Pharma: Other: provided consultations ; Bristol Myers Squibb: Other: provided consultations and performed lectures; Novartis: Other: provided consultations and performed lectures. Abruzzese:Pfizer: Consultancy; BMS: Consultancy; Novartis: Consultancy; Ariad: Consultancy. Rea:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria. Kim:BMS: Research Funding; Pfizer: Research Funding; Novartis: Research Funding; Ilyang: Research Funding. Chabaeva:Russian Foundation for Basic Research grant 18-015-00399 A: Research Funding. Kulikov:Russian Foundation for Basic Research grant 18-015-00399 A: Research Funding. Turkina:Novartis: Other: provided consultations; Bristol Myers Squibb: Other: provided consultations; Phizer: Other: provided consultations; Fusion Pharma: Other: provided consultations.

Pregnancy in CML patients (pts) is becoming a reality due to the increase in information from published cases or larger multicentric database (GIMEMA and ELN). Interferon (IFN) has been used during pregnancy, but little is known about the use of tyrosine kinase inhibitors (TKIs), which should be stopped early due to their teratogenic effects. Female pts can ideally plan a pregnancy if they are in a deep, stable, molecular response (DMR=MR≥ 4, ≤0.01%IS) and treatment free remission (TFR) parameters are satisfied. Molecular remission can be maintained throughout the pregnancy, but how to proceed if the remission is rapidly lost, or if the patient is not in DMR, or when CML is discovered during pregnancy? To address these questions, we analyzed more than 300 pregnancies registered through the ELN database. Pts completing pregnancy were grouped as follow: 1) pts diagnosed with CML while pregnant 2) pts in DMR 3) pts with ≤MR3 (≥ 0.1%IS) In 47 patients CML was diagnosed during pregnancy, 21 during the 1st trimester, 15 in the 2nd , and 11 in the 3rd (range 3-38 wk). Sixteen patients were not treated until delivery, 15 were treated with IFN; 19 with Imatinib (IM), 12 in the 2nd trimester (&gt;16 wk), and 7 in the 3rd. Forty-eight children were born (one set of twins). Three were preterm (35-37 wk), and one pregnancy is ongoing. No births defects were observed. Seven newborns had a low birth weight (&lt; 2.5 Kg) 6 of them were exposed to IM at late pregnancy and 3 were preterm. Follow-up was uneventful. The majority of pts achieved ≥ MR3 after starting TKI. Two pts died: 1 in blast crisis (BC) after 9 years, but she was not adherent to treatment; 1 of transplant complication (resistant to&gt;2TKI). Seventy five pts had 80 pregnancies in DMR. Six were in TFR (no therapy) for more than 12 mo, while 8 stopped TKI in order to conceive (2-8 mo before conception). Twenty two pts were treated during pregnancy: 12 with TKI (8 IM, 4 nilotinib, NIL) 1 in the 1st trimester (never stopped IM), 7 in the 2nd and 4 in the 3rd; 10 pts received IFN. Eighty one children were born (6 patients had 2 pregnancies, 1 had twins) with one baby born preterm (wk 35). No births defects were observed and two pregnancies are ongoing. Fifty eight pregnancies were carried without any CML treatment. Twenty six maintained DMR, 28 ≤ MR3 and considered in "treatment free pregnancy" (TFP), and 5 had &gt;10% transcript levels at delivery, considered as high tumor burden (HTB). None of the patients progressed after pregnancy, 4 patients maintained TFR. Four patients did not return to MR3 &lt;12 months after restarting TKI; 3 were switched to a more potent TKI rapidly achieving ≥ MR3, while 1 pt, who did not, is in hematologic remission after 3 years. Pts belonging to ≤MR3 do not satisfy TFR criteria, and were discouraged from starting a pregnancy. However 95 pregnancies (90 pts) were reported; 29 had stopped TKI prior to conception (5 of them had HTB at pregnancy onset). Fifty eight (61%) were treated with IFN (20), TKIs (35), or HU (3). Thirteen patients were treated with IM during 1st trimester (10 throughout the pregnancy). Among the untreated pts, 6 were surprisingly in DMR at delivery, 20 were in TFP, and 11 had HTB. Two babies were born with polydactyly and hypospadias (IFN treatment since 1st trimester), and 2 exhibited a non-closed foramen ovale (IM during 2-3rd trimester) which was considered unlikely to be related to treatment. Four pts progressed in BC and died after pregnancy but all were not compliant to therapy. This is the first, large, multicenter report focusing on treatment during pregnancy. Results suggest that CML patients can pursue a normal life including planning a family, with several caveats. Based on the different situations examined, treatment with IFN is confirmed safe. In contrast TKIs should not be used during pregnancy. Selected TKIs, specifically IM and NIL which have little placental transfer, can be started after organogenesis. Pts at onset can delay therapy without jeopardizing the future CML outcome. If therapy during pregnancy is deemed necessary, IFN can induce and maintain hematologic remission, or, if introduced earlier, preserve molecular remission after TKI interruption, while TKIs can reduce HTB. Caution should be taken when considering stopping TKI prior to conception due to the possibility of losing response, while an early stop (at first positive pregnancy test, 4-5 wk) could be considered. Detailed results, mother and child follow up and practical management will be presented. Disclosures Abruzzese: BMS: Consultancy; Incyte: Consultancy; Novartis: Consultancy; Pfizer: Consultancy. Turkina:Pfizer: Consultancy; Bristol Myers Squibb: Consultancy; Novartis: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; fusion pharma: Consultancy. Apperley:Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Kim:Novartis: Research Funding; BMS: Research Funding; Pfizer: Research Funding; Il-Yang co.: Research Funding; Takeda: Research Funding. Garcia-Gutiérrez:Novartis: Honoraria, Other: Advisory Committees. Mauro:Novartis Oncology: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy; Pfizer: Consultancy; Takeda: Consultancy. Milojkovic:Novartis: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Pfizer: Honoraria, Speakers Bureau; BMS: Honoraria, Speakers Bureau. Moriaghi:novartis: Speakers Bureau; BMB: Speakers Bureau; Takeda: Speakers Bureau. Nicolini:Incyte Biosciences: Honoraria, Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau; Sun Pharma Ltd: Consultancy. Rea:Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria; Incyte Biosciences: Honoraria. Rousselot:Pfizer: Research Funding; Incyte: Research Funding. Shacham:novartis: Consultancy. Trawinska:Novartis: Consultancy, Honoraria. Chelysheva:Fusion Pharma: Consultancy; Novartis: Consultancy, Honoraria. OffLabel Disclosure: informations on the use of interferon and/or TKIs (imatinib, nilotinib) during pregnancy.