ALBERT

Description: Abstract 2181 Background: Acute Myeloid Leukemia (AML) in the elderly is notoriously difficult to treat and has a low remission rate with very few long term survivors when using standard treatment approaches. Azacytidine, a hypomethylating agent, has been shown to induce remission and prolong survival in patients with myelodysplastic syndromes; studying this approach to patients with AML is therefore warranted. We present results of an ongoing phase II trial treating elderly or frail AML patients with Azacytidine. Methods: AML elderly or frail patients, and therefore unfit for an intensive chemotherapy regimens, with a WHO performance status ≤ 3 were considered for this trial. Trial therapy consisted of 100mg/m2 of Azacytidine injected subcutaneously on 5 consecutive days every 28 days up to 6 cycles, stopping at 6 months if no hematological improvement achieved, or earlier in the case of progression or complications. Treatment was continued beyond 6 months in responding patients. Trial therapy was considered uninteresting if the response rate (CR + PR) within 6 months of therapy initiation was 15% or less and promising if 34% or more. Using the exact single-stage phase II design by A’Hern with a 5% significance level and 90% power, 43 patients were required: If 10 or fewer achieved a response within 6 months the trial therapy should not be considered for further investigation in its current format for this indication and patient population. Results: Between September 2008 and January 2010, 45 evaluable patients across 10 Swiss centers were accrued with a median follow-up of 7 months (range: 0 – 13). 27 (60%) were male, median age was 74 (range: 55 – 86) years and 35 (78.8%) had performance status 0–1. Patients had been excluded from more intensive chemotherapy regimens because of age (n = 37) or due to comorbidities or patient refusal (n=8). Five patients had therapy related AML. Patients received a median of 3 (range: 1 – 10) cycles. Treatment was stopped for not achieving a response by the 6th cycle in 2 patients and earlier in 26 patients (for disease progression in 5, toxicity in 3, patient refusal in 2, recurrent infections in 1, and death in 8). Seventeen patients remain on therapy. The median time spent in the hospital was 12 days (1 - 30) in 24/38 patients hospitalized during the first treatment cycle and 13 days (2 - 28) in 15/31 patients hospitalized during subsequent cycles. Adverse events of grade III or higher most frequently reported were constitutional or hematologic, i.e. fatigue in 5, febrile neutropenia in 8, infections in 6, dyspnea in 6, anemia in 3, neutropenia in 12 and thrombocytopenia in 10, hemorrhage in 2 and retinal detachment in 5. Based on available data on 38 patients, CR/CRi or hematologic improvement or stable disease within 6 months of trial registration was observed in a proportion of patients. Final and mature data, determining whether the predefined proportion of responding patients has been reached or not, will be presented at the conference. Up to now there were a total of 26 deaths. Median overall survival time was 5.7 months (95% CI: 3.1, 8.7). Conclusions: The current results of this slightly modified Azacytidine schedule demonstrate a feasible new therapy option for elderly or frail AML patients in an outpatient setting with moderate, mainly hematologic toxicity. Disclosures: No relevant conflicts of interest to declare.

Description: Evolution of the chronic lymphocytic leukemia (CLL) clone upon treatment with the BTK-inhibitor ibrutinib has never been systematically assessed in a prospective way, though changes in the tumor genetic composition have been anecdotally reported by retrospective backtracking of mutations acquired in ibrutinib-refractory patients. The IOSI-EMA001 observational study (NCT02827617) enrolls patients treated with ibrutinib in the clinical practice, and aims at prospectively assessing the dynamics of the clonal architecture of high risk CLL upon therapy with ibrutinib by taking advantage of leukemia samples homogeneously collected at pre-specified timepoints during treatment course. Ibrutinib induces a transient lymphocytosis by displacing CLL cells formerly residing in the tissue compartments into the peripheral blood (PB). By analyzing samples collected after two weeks of ibrutinib treatment, here we tracked early genetic changes of the CLL clone occurring at the time of redistribution lymphocytosis. This analysis includes the first 10 patients enrolled in the study (median age=76 years; Binet A=10%, B=60%, C=30%; IGHV unmutated=60%, mutated=20%, NA=20%; 17p deletion=40%). PB samples were collected before ibrutinib treatment start (day -28 to 0) and after two weeks of treatment (week 2, +/-3 days). Tumor genomic DNA was isolated from FACS sorted CLL cells (CD19+/CD5+ elements; 〉99% purity). T cells were also sorted as source of germline material to confirm the somatic origin of mutations and filter out sequencing noise. The HaloPlex High Sensitivity library preparation protocol and ultra-deep next generation sequencing (coverage ~40.000x) on MiSeq (Illumina) were used to track TP53, BTK and PLCG2 mutations. By uniquely molecular barcoding each DNA library fragment, and by targeting both DNA strands, this approach allowed to reach a sensitivity of 10E-4. The CAPP-seq library preparation protocol and deep next generation sequencing (sensitivity ~5x10E-3) were used to track mutations of a panel of genes known to be recurrently affected in CLL (ASXL1, ATM, BIRC3, BRAF, EGR2, FBXW7, IKZF3, IRF4, KRAS, MAP2K1, MGA, MYD88, NFKBIE, NFKB2, NOTCH1 including 3'UTR, PAX5 enhancer, POT1, RPS15, SAMHD1, SF3B1, TP53, XPO1, ZMYM3). At baseline before treatment start, 33 non-synonymous somatic mutations (allele frequency: 0.65-99%) were identified in 9 of the 10 cases (one patient was devoid of mutations of the above-mentioned genes). The mutational profile was consistent with that expected in a high risk population meeting the current indication for ibrutinib treatment in the clinical practice(TP53=60%; NOTCH1=40%; MGA=30%; ZYMYM3=20%; ATM=10%; BIRC3=10%; EGR2=10%; IRF4=10%; IKZF3=10%; MYD88=10% NFKBIE=10%; SF3B1=10%; XPO1=10%) (Fig. 1A). Before treatment start, high sensitive ultra deep next generation sequencing did not disclose any non-synonymous somatic mutation of BTK and PLCG2 in CLL cells circulating in the blood. The genetic composition of the circulating leukemia clone did not significantly change after two weeks of treatment despite redistribution of CLL cells in the blood compartment (median lymphocyte count at baseline 50.9x10E9/L vs 77.5x10E9/L at week 2) (Fig 1B). Minor genetic changes between baseline and week 2 included the appearance of a small clone mutated in SAMHD1 and the disappearance of a small clone mutated in BIRC3 in 2 different patients. At week 2, no mutations of BTK and PLCG2 became evident in the circulating compartment. With the limitation of the current sample size, these data suggest that redistribution lymphocytosis does not mobilize CLL high risk clones harboring mutations of clinical relevance into the blood compartment. Figure 1 Figure 1. Disclosures Rossi: Gilead: Honoraria, Research Funding; Janssen: Honoraria; AbbVie: Honoraria.

Description: Introduction: FCR is still the standard frontline regimen for physically fit CLL pts without TP53 alteration. The international phase III CLL10 study demonstrated the inferiority of BR in comparison to FCR in this population. In order to evaluate long-term outcome and toxicity we performed an updated analysis after extended observation time. Methods and Patients: 561 pts were randomized as previously published (Eichhorst B et al., Lancet Oncol 2016). 282 and 279 pts were randomized to receive either 6 courses of FCR or BR respectively. After the end of treatment pts were followed 3-monthly for 2 years (yrs) and 6-monthly for 3 yrs, and afterwards annually until progressive disease (PD). After PD annual visits were documented either within the study or within the registry of the GCLLSG. Health related quality of life (HRQOL) was evaluated by using the EORTC C30 questionnaire, which was completed at baseline, after 3, 6 and 12 months and then annually until year 5. Results: After a median observation time of 58.2 months (mo) (range, 0 - 88 mo), the median progression-free survival (PFS) for FCR was 57.6 mo versus (vs) 42.3 mo for the BR arm [Hazard ratio (HR)=1.593 (95% confidence interval (CI), 1.271-1.996); p 65 yrs] (57.6 vs 42.3; p=0.134). Richter transformation (RT) was assessed as PD and occurred in 5 pts (1.8%) after FCR and 8 pts (2.9%) after BR. 77 (27.3%) pts following FCR and 108 (38.7%) following BR treatment received at least one subsequent therapy. BR was the most common second line therapy after prior FCR (42 pts), while BR re-exposure after frontline BR was performed in 31 pts. 33pts switched to FCR after BR first line therapy. So far, only 3 pts after FCR and 2 pts after BR received kinase inhibitors. 51 pts (18.1%) of the FCR arm and 54 (19.4%) pts of the BR arm deceased so far. Main cause of death in the FCR arm were secondary malignancies (14 pts; 5.0%), followed by CLL including RT (11 pts incl. 2 RT; 3.9%), infections (7 pts; 2.5%) and concomitant diseases (6 pts; 2.1%). In the BR arm CLL was the most common cause of death (15 pts incl. 6 pts with RT; 5.4%) followed by infections (12 pts; 4.3%) and concomitant disease and secondary malignancies (10 pts each; 4.3% each). Other causes of deaths were distributed similarly (incl. adverse events to frontline or relapse treatment or unknown). No differences in overall survival (OS) were observed (OS at 5 yrs, 80.9% for FCR vs 80.1% for BR; HR=1.108, 95% CI 0.755-1.627; p=0.599). The difference in OS for younger pts was statistically not significant (OS at 5-yrs 85.6% for FCR vs 81.1% for BR; p=0.119). Otherwise, 5-yrs OS was 78.8% for pts 〉 65 yrs receiving BR and 70.9% for those receiving FCR (p=0.238). Multivariate analysis identified treatment arm, male sex, high serum thymidine kinase (TK), del(11q) and unmuated IGHV status, but not age as independent prognostic factors for PFS. For OS only high serum TK and unmutated IGHV status were assessed as independent prognostic factors. Secondary neoplasia was documented in 49 (17.6%) of 279 FCR treated pts and 35 (12.5%) of 278 BR treated pts. No difference in the incidence rate of secondary solid tumors was observed between both arms (for FCR 28 (10.0%) and for BR 25 (9.1%)). Secondary MDS and/or AML occurred more frequently after FCR therapy (12 [4.3%] vs 2 [0.7%]), particularly in pts 〉65 yrs (6 [7.0%] vs 1 [0.9%]). 540 of 561 pts (96.3%) were evaluable for HRQOL analysis, 272 pts of the FCR and 268 pts of the BR arm. No differences between both arms were detected with respect to global health status or any functional or symptom scale. As compared to an age- and sex-matched normal population functional scale values were impaired mostly during treatment phase and symptom scales also during follow-up. However, after the end of therapy and during follow-up global health status was improved. Conclusion: Long-term follow-up data of the CLL10 study confirm the superiority of FCR regimen in young (≤ 65 yrs) and fit CLL patients. However, importantly these data support the recommendation of using BR in fit elderly pts. This particular group of pts had both a very good outcome after BR and compared to FCR a decreased risk of secondary MDS and/or AML. Disclosures Eichhorst: Novartis: Consultancy; Gilead: Consultancy, Research Funding, Speakers Bureau; Abbvie: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Research Funding, Speakers Bureau; Celgene: Speakers Bureau; Roche: Consultancy, Research Funding, Speakers Bureau; Mundipharma: Consultancy, Research Funding, Speakers Bureau. Bahlo:F. Hoffman-La Roche: Honoraria, Other: Travel grant. Maurer:Mundipharma: Other: Travel grants. Kiehl:Roche: Consultancy, Other: Travel grants, Speakers Bureau. Fischer:Roche: Other: travel grants. Kneba:Amgen: Research Funding; Roche: Consultancy, Honoraria, Other: Travel grants, Research Funding; Gilead: Consultancy, Honoraria, Other: Travel grants, Research Funding; AbbVie: Consultancy, Honoraria, Other: Travel grants; Glaxo-SmithKline: Other: Travel grants; Janssen-Cilag: Consultancy, Honoraria, Other: Travel grants. Wendtner:Hoffmann-La Roche, Mundipharma, Janssen, Gilead, Abbvie, Servier, Morphosys: Consultancy, Other: Travle grants, Research Funding. Klapper:Roche, Novartis, Amgen, Takeda: Research Funding. Kreuzer:Roche Pharma GmbH and Mundipharma GmbH: Consultancy, Honoraria, Research Funding, Speakers Bureau; Gilead Sciences: Consultancy, Honoraria, Research Funding, Speakers Bureau. Böttcher:Celgene: Research Funding; Hoffmann-LaRoche: Honoraria, Other: Travel grants, Research Funding; AbbVie: Honoraria, Research Funding. Stilgenbauer:GSK: Consultancy, Honoraria, Other: Travel grants , Research Funding; AbbVie: Consultancy, Honoraria, Other: Travel grants, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel grants, Research Funding; Novartis: Consultancy, Honoraria, Other: Travel grants , Research Funding; Genzyme: Consultancy, Honoraria, Other: Travel grants , Research Funding; Gilead: Consultancy, Honoraria, Other: Travel grants , Research Funding; Hoffmann-La Roche: Consultancy, Honoraria, Other: Travel grants , Research Funding; Celgene: Consultancy, Honoraria, Other: Travel grants , Research Funding; Genentech: Consultancy, Honoraria, Other: Travel grants , Research Funding; Mundipharma: Consultancy, Honoraria, Other: Travel grants , Research Funding; Pharmacyclics: Consultancy, Honoraria, Other: Travel grants , Research Funding; Janssen: Consultancy, Honoraria, Other: Travel grants , Research Funding; Sanofi: Consultancy, Honoraria, Other: Travel grants , Research Funding; Boehringer Ingelheim: Consultancy, Honoraria, Other: Travel grants , Research Funding. Fink:Celgene: Research Funding; Roche: Honoraria, Other: Travel grants; Mundipharma: Other: Travel grants; AbbVie: Other: Travel grants. Hallek:Celgene: Research Funding; Roche: Consultancy, Honoraria, Research Funding; Gilead: Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Honoraria; GSK: Research Funding; Mundipharma: Research Funding; Janssen: Research Funding.

Description: Rationale: Proteasome inhibitor-refractory multiple myeloma (MM) patients are a difficult to treat population with a very poor prognosis. The activity of registered, current or next generation MM drugs (pomalidomide, carfilzomib, daratumumab) in heavily pretreated, proteasome inhibitor-refractory MM is in the range of 30%. The biology of proteasome inhibitor resistance is driven by adaptive downregulation of the unfolded protein response (UPR), which regulates plasma cell maturation and sensitivity to proteasome inhibitor treatment (Leung-HagesteijnC. et al., Cancer Cell 2013 Sep 9;24(3):289-304). The oral HIV protease inhibitor nelfinavir (NFV) has anti-MM activity in vivo, triggers UPR activation, sensitizes MM to proteasome inhibitors and overcomes proteasome inhibitor resistance in vitro. Combination therapy with NFV and bortezomib (BTZ) showed UPR activation in vivo and strong signals of activity in bortezomib-refractory MM in the SAKK 65/08 phase I trial (Driessen C. et al.,Haematologica 2016 Mar;101(3):346-55). Objective: We performed a prospective, multicenter phase II trial to assess the activity ofnelfinavir,bortezomiband dexamethasone (NVd) in proteasome inhibitor-refractory MM. Methods: Patients with progressing, measurable, proteasome inhibitor-refractory MM (IMWG criteria) were included in this multicenter phase II trial. Further selection criteria included WHO performance status ≤ 3, platelets ≥ 50 x 109/L, hemoglobin ≥ 80 g/L (both may be achieved by transfusion) and adequate hepatic function. Concomitant use of other anti-cancer medication or radiotherapy, except for local pain control, was excluded. Patient age or prior number or types of therapy were not limited. Simon's two stage design was used to differentiate a promising activity (best response at any time point, partial response (PR) or better, ≥ 35 %) from an uninteresting activity (≤ 15% PR; power 80%, alpha 5%). Results: 34 patients were treated with oral nelfinavir 2500 mg days 1-14 b.i.d. in combination with bortezomib + dexamethasone (BTZ 1.3 mg/m2 days 1, 4, 8, 11, dexamethasone 20 mg p.o. days 1-2, 4-5, 8-9, 11-12) for a maximum of 6 21-day cycles at 9 SAKK trial sites throughout Switzerland. Patients (median age 67.5 years, range 42-82 years) had a median of 5 (range 2-12) prior therapy lines, 26 (76%) patients had prior high dose chemotherapy, and 13 (39%) had known poor prognosis cytogenetic abnormalities. All treated patients had proteasome inhibitor refractory MM according to IMWG criteria, i.e. they had progressed during or within 60 days after adequately dosed proteasome inhibitor-containing therapy. Moreover, 26 (76%) patients werelenalidomide-refractory by IMWG criteria (double refractory). Trial therapy is still ongoing in 2 patients. The median number of treatment cycles delivered per patient is 4. 22 patients achieved an objective response with a PR or better, resulting in an overall response rate (OR) of 65% (90% CI 49.2%-75.7%) to date. VGPR was reached in 5 patients, PR in 17 patients, MR in 3 patients, SD in 4 patients and PD in 3. Inpatients double-refractory for proteasome inhibitors andlenalidomide, the OR was 69%, in patients with poor prognosis cytogenetic abnormalities it was 77%. The OR was independent from the number of prior therapy lines (OR rate 69% with 〈 5 prior therapy lines, OR rate 61% with ≥ 5 prior lines). Most frequent 〉 grade (G) 2 adverse events to date were anemia (G3 29%), thrombocytopenia (G3 24%, G4 18%), infections (G3 24%, G4 9%, G5 3%), hyperglycemia (G3 18%, G4 3%) and fatigue (G3 12%). Six patients maintained their PR or better for the full 6 cycles per protocol while on study. Four patients continuedNVd therapy on a compassionate use basis after completing the study. Updated final data will be provided at the meeting. Conclusion: Nelfinavir in combination with bortezomib and dexamethasone (NVd) is a reasonable, active, safe and widely available treatment option for patients with proteasome inhibitor-refractory multiple myeloma. The objective response rate of 65% observed in this very advanced, heavily pretreated, mostly dual-refractory patient population is exceptional. Our results warrant further development of nelfinavir as a sensitizing drug for proteasome inhibitor-based treatments and promising new agent for MM therapy. Figure Maximum relative change in serum M-protein or serum free light chain concentration in individual evaluable patients. Figure. Maximum relative change in serum M-protein or serum free light chain concentration in individual evaluable patients. Disclosures Driessen: Mundipharma-EDO: Honoraria, Membership on an entity's Board of Directors or advisory committees; celgene: Consultancy; janssen: Consultancy. Samaras:Celgene (Adboard, educational talk), Amgen (adboard), Takeda (Adboard), Roche (Adboard), Sanofi (Adboard), Novartis (Adboard): Consultancy, Honoraria. Zander:Bristol Myers, Celgene, Amgen, Mundipharma, Janssen-Cilag, Takeda Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Description: Introduction FCR is the current standard first line treatment regimen in advanced CLL (Hallek et al., Lancet, 2010), but is associated with significant side effects. The GCCLSG initiated an international phase III study in order to test the non-inferiority regarding efficacy and potentially better tolerability of BR compared to FCR in first-line therapy of physically fit pts without del(17p). Methods and Patients 688 CLL pts from 158 sites in five countries (Germany, Austria, Switzerland, Denmark and Czech Republic) were screened centrally for immunophenotype, genomic aberrations by FISH, IGHV sequenzing, comorbidity burden and renal function. 564 CLL pts with CIRS score ≤ 6, creatinine clearance 〉 70 ml/min and without del(17p) were enrolled between October 2008 and June 2011. Pts were randomly assigned to receive 6 courses of either FCR (N= 284; F 25mg/m2 i.v. d1–3, C 250 mg/m2 i.v. d1–3, R 375 mg/m2 i.v. d 0 at first cycle and 500 mg/m2 d1 all subsequent courses; q 28 days) or BR (N=280; B 90mg/m2 i.v. d1+2, R 375 mg/m2 i.v. d 0 at first cycle and 500 mg/m2 d1 all subsequent courses; q 28 days). The intent-to-treat population consisted of 561 pts, because three patients were excluded due to deferred treatment (1 pt decision, 1 treatment before randomization, 1 misdiagnosis). 22 % were Binet A, 38 % Binet B and 40 % Binet C. The median age was 62 years (yrs) (range 33 to 82), median CIRS score 2 (range 0-6). There were significantly more pts with unmutated IGVH in the BR arm (68%) in comparison to the FCR arm (55%; p=0.003). All other characteristics including median age were well balanced. A mean number of 5.27 courses was given in the FCR arm versus 5.41 courses in the BR arm (p=0.022). 70.6% (FCR) and 80.3% (BR) of pts received 6 courses (p=0.008). Dose was reduced by more than 10% in 27.3% (FCR) and 31.6% (BR) of all courses given (p = 0.012). Results The median observation time was 27.9 months (mo) in all pts alive. While response evaluation was missing in 14 pts, 547 pts (274 FCR; BR 273) were evaluable for response and all 561 pts (282 FCR; 279 BR) for progression-free survival (PFS), event-free survival (EFS) and OS. The overall response rate was identical in both arms with 97.8% (p=1.0). The complete response rate (CRR) (confirmed by central immunhistology) with FCR was 47.4% as compared to 38.1% with BR (p=0.031). MRD data were available at interim analysis from 192 pts (99 FCR; 93 BR) of the first 300pts. 71.7% of pts in the FCR and 66.7% in the BR arms achieved MRD-levels below 10-4 in peripheral blood at final staging (p=0.448). The complete MRD data set will be available by November. PFS was 85.0% at 2 yrs in the FCR arm and 78.2% in the BR arm (p=0.041). EFS was 82.6% at 2 yrs in the FCR arm and 75.7% in the BR arm (p=0.037).There was no difference in OS rate for the FCR vs BR arm (94.2% vs 95.8% at 2 years p=0.593). Hazard Ratio for PFS, EFS and OS was 1.385, 1.375 and 0.842 respectively. PFS was assessed in pts 〈 65 yrs and ≥ 65 yrs. While there was a significant difference in pts 〈 65 yrs between both treatment arm (median PFS for BR 36.5 mo vs not reached for FCR; p=0.016), the difference disappeared in elderly pts (not reached vs. 45.6 mo; p=0.757). A multivariate analysis including treatment arm, Binet stage, age, sex, comorbidity, serum TK, serum beta2-microglobulin (Beta2M), del(11q) and IGHV status identified treatment arm, Beta2M, del(11q) and IGHV as independent prognostic factors for PFS and EFS. FCR treated pts had significantly more frequent severe, CTC grade 3 to 5, adverse events during the whole observation period (90.8% vs 78.5%; p

Description: Chronic lymphocytic leukemia (CLL) occurs in older individuals with a median age at diagnosis of 72 years. In recent years, there has been considerable progress in the frontline therapy of elderly/physically unfit patients with CLL. The German CLL11 trial showed that addition of obinutuzumab to chlorambucil (G-Clb) prolongs progression free survival (PFS) and overall survival (OS) compared to chlorambucil alone or in combination with rituximab. More recently, obinutuzumab together with ibrutinib or venetoclax were shown to be superior to G-Clb with regard to PFS, but there was no advantage in terms of OS. In this retrospective, multinational and multicenter co-operative study the European Research Initiative on CLL (ERIC) and the Israeli CLL Study Group (ICLLSG) evaluated the efficacy of frontline treatment with G-Clb in patients with CLL, in a "real-world" setting. Our analysis excluded CLL patients with documented del(17p) or TP53 mutations since they are no longer treated with chemotherapy. Results: A total of 437 treatment-naïve patients with CLL from 51 medical centers located in 13 countries were included. The median age of this patient population was 75.9 years; 59.7% were men, median CIRS total score was 8 and estimated creatinine clearance 61.1 mL/min. Seventy four patients had Binet stage A (17.2%), 167 (38.8%) stage B and 190 (44.1%) stage C. Results of FISH and IGHV mutational status were available for 332 and 115 patients, respectively. High-risk cytogenetics, del(11q) was documented in 18.7% patients and IGHV-unmutated gene in 64.4%. The vast majority of patients were treated with G-Clb (N=408) and the rest with obinutuzumab monotherapy (G-monotherapy, N=29). The clinical overall response was 86.5%, including clinical complete and partial responses in 41.6% and 45.8% of cases, respectively. The median observation time was 14.1 months (m) and the median PFS of the entire cohort was 27.6m (95% CI, 24.2-31.0). The PFS for G-Clb was significantly better than G-monotherapy (P=0.001; HR=0.38, 95% CI: 0.22-0.67), being the 2-year PFS estimates 61.8% and 52.8%, respectively. The median PFS was significantly shorter for patients with del(11q) (19.2m) compared to those with normal FISH (not reached, P

Description: Introduction. Ibrutinib inhibits the BTK molecule downstream the B-cell receptor (BCR). Though highly active in high risk chronic lymphocytic leukemia (CLL), the most typical response achievable in patients is a minimal residual disease (MRD) positive partial remission (PR) which is maintained until the development of genetically driven resistance caused by the acquisition of mutations in the BTK or PLCG2 genes. The study aims at characterizing the adaptation process allowing residual CLL cells to persist despite BTK inhibition. Methods. The IOSI-EMA-001 study (NCT02827617) is an observational study consisting in the prospective and longitudinal collection of peripheral blood samples and clinical data from high risk CLL patients treated with ibrutinib. Peripheral blood CLL cells longitudinally drawn from patients before treatment start and at fixed timepoints under ibrutinib were monitored by: i) next generation flow cytometry approaches for changes in proliferation rate, surfaceome, and pathway activation; and ii) CAPP-seq targeted deep next generation (sensitivity ~10-3) for clonal evolution. Results. The study cohort comprised 31 high risk CLL patients, including 15 treatment naïve, 16 relapsed, 80% IGHV unmutated, 42% 17p deleted and 55% TP53 mutated. Median duration of ibrutinib treatment was 45 weeks (24-72 weeks). All patients obtained a MRD positive PR that was maintained in all but one who progressed with a PLCG2 mutation (VAF 3%). Compared to baseline, under ibrutinib therapy CLL cells slowed down their proliferation, as suggested by the decreased expression of Ki-67, the reduction of the proliferating fraction (CXCR4dimCD5bright), and the increase of the resting fraction (CXCR4brightCD5dim). Compared to baseline, under ibrutinib therapy CLL cells also upregulated BCR and adhesion/homing proteins, and decreased the expression of BCR inhibitor proteins. Upon stimulation of the BCR with anti-IgM, the downstream path through pBTK and pPLCG2 was inhibited by ibrutinib, while conversely the downstream path through pAKT and pERK was still inducible throughout all the assessed timepoints. The proportion of CLL cells harboring nuclear localization of NF-kB progressively increased over time under ibrutinib. NF-kB nuclear localization was inducible throughout all the assessed timepoints by CD40L stimulation of the non-canonical NF-kB pathway, but not by anti-IgM stimulation of the BCR/canonical NF-kB pathway. Overall, 880 individual mutations were longitudinally discovered and monitored across a total of 121 sequential timepoints collected during ibrutinib treatment. Clonal evolution was observed in (67.7%) cases, a proportion rate previously documented in CLL treated with chemoimmunotherapy. Clonal evolution appeared to be heterogeneous involving different genes without a stereotypic targeting. Consistently, none of the main driver gene mutations was homogeneously selected or suppressed by ibrutinib suggesting that the biological adaptation of CLL cells under ibrutinib is not genetically driven. Clonal evolution propensity was not associated with any of the biomarkers of the disease, and it did not decrease over time under ibrutinib. Conclusions. Taken together these results suggest that residual CLL cells persisting under ibrutinib therapy adapt their phenotype by upregulating adhesion molecules, chemokine receptors and BCR molecules, and by maintaining a competence of BCR signaling through the PI3K/AKT/ERK pathway. The progressive selection of CLL cells having NF-kB in the nucleus, likely due to the BTK independent non-canonical NF-kB pathway, might explain their survival despite ibrutinib therapy. Finally, clonal evolution is not suppressed by ibrutinib chemotherapy, and despite does not seem to be directly involved in such adaptation process, may ultimately favor the acquisition of BTK and PLCG2 ibrutinib resistance mutations. Disclosures Zucca: Celltrion: Consultancy; AstraZeneca: Consultancy. Ghia:Sunesis: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; AbbVie, Inc: Honoraria, Research Funding; Acerta: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria, Research Funding; BeiGene: Honoraria, Research Funding. Montillo:Janssen: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Speakers Bureau; AbbVie: Consultancy, Honoraria, Speakers Bureau; Roche: Consultancy, Honoraria, Research Funding. Tedeschi:Janssen: Consultancy, Speakers Bureau; Gilead: Consultancy; AbbVie: Consultancy. Gaidano:AbbVie: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Morphosys: Honoraria; Roche: Consultancy, Honoraria.

Description: Introduction: For physically fit CLL pts with low comorbidity burden FCR is the standard frontline regimen in advanced CLL. The CLL10 study, an international phase III study evaluated the efficacy and tolerance of BR in comparison to FCR in frontline therapy of fit pts without del(17p). Methods and Patients: 158 sites in five countries (Germany, Austria, Switzerland, Denmark and Czech Republic) registered 688 CLL pts for central screening including immunophenotyping, FISH, comorbidity burden and renal function. 564 CLL pts with CIRS score ≤ 6, creatinine clearance 〉 70 ml/min and without del(17p) were enrolled between 10/2008 and 6/2011. Pts were randomly assigned 1:1 to receive 6 courses of FCR (N= 284; F 25mg/m2 i.v. d1–3, C 250 mg/m2 i.v. d1–3, R 375 mg/m2 i.v. d 0 at first cycle and 500 mg/m2 d1 all subsequent cycles; q 28 days) or BR (N=280; B 90mg/m² i.v. d1+2, R 375 mg/m2 i.v. d 0 at first cycle and 500 mg/m2 d1 all subsequent cycles; q 28 days). A general prophylactic use of antibiotics or growth factors was not recommended. Three patients (2 FCR, 1 BR) were excluded because of deferred treatment. The median CIRS score was 2. There was no difference in median age (61.6 years (yrs) for all pts), but a significantly higher proportion of pts ≥ 70 yrs was included in the BR arm (22% vs 14%, p=0.020). Binet A was present in 22%, Binet B in 38 % and Binet C in 40 %. Unmutated IGHV status was not balanced between both groups (68% in BR versus 55% in FCR arm; p=0.003). All other characteristics showed no differences. The mean number of administered FCR courses was 5.27 courses vs 5.41 BR course (p=0.017). Results: The median observation time for all patients was 35.9 months (mo). 547 pts (FCR 274 ; BR 273) were evaluable for response and all pts (282 FCR ; 279 BR) included for progression-free survival (PFS) and overall survival (OS) analysis. The overall response rate in both arms was 97.8% (p=1.0). The complete response (CR) rate according to IWCLL and confirmed by central bone marrow immunohistology was 40.7% with FCR compared to 31.5% with BR (p=0.026). Four-colour-flow MRD data from peripheral blood (sensitivity 10-4) were available from 355 pts (185 FCR; 170 BR) at final staging. In the FCR arm 74.1% and 62.9% in the BR arm respectively of all evaluated pts were MRD negative (p=0.024). Bone marrow samples, available in 129 FCR and 98 BR pts, were MRD negative in 58.1% and 31.6% of pts, respectively (p