TIME-LIMITED TREATMENT WITH ACALABRUTINIB PLUS OBINOTUZUMAB IN TREATMENT-NAÏVE CHRONIC LYMPHOCYTIC LEUKEMIA PATIENTS INDUCES DEEP REMISSIONS: EARLY RESULTS OF AN ONGOING PHASE 2 TRIAL

Background: The Bruton's tyrosine kinase (BTK) inhibitor acalabrutinib is approved for treatment of chronic lymphocytic leukemia(CLL). Acalabrutinib induces durable remissions in most CLL patients, which mostly are partial remissions (PR), and therefore treatment typically is given as long-term monotherapy. As a potential alternative we developed a time-limited regimen, combining acalabrutinib with obinutuzumab. Aims: Here, we report early results from 14 treatment-naïve patients with CLL who enrolled in this ongoing phase 2 trial (NCT04505254) since September, 2020 at MD Anderson Cancer Center. Methods: Patients and Study Design: Treatment-naïve CLL patients requiring therapy as per iwCLL criteria receive acalabrutinib 100 mg orally twice a day for 24 cycles, combined with monthly obinotuzumab for 6 doses, starting in cycle 3. The first dose of obinutuzumab is divided into 100 mg on day 1 and 900 mg on day 2 of cycle 3;1000 mg are given during subsequent cycles (cycles 4-8). Patients who do not achieve a complete remission (CR) after cycle 8 can receive an additional 6 monthly doses of obinotuzumab during cycles 9 -14. Treatment is discontinued after 24 cycles, and patients will be monitored. The primary objective is to determine the durability of remissions after treatment discontinuation, secondary objectives are to determine clinical and laboratory characteristics that predict for early versus late relapse after time-limited therapy. Results: The median age of the patients is 70 yrs (range, 40 -83 yrs), 14% had del17p or TP53 mutation, 43% had an unmutated IgHV and 71% advance stage disease (RAI stage III and IV). The median baseline absolute lymphocyte count (ALC) and b2 microglobulin at start of therapy were 39.2x109/L (range: 7.1 - 188.4 x 109/L) and 4.2 mg/L (range: 2.2 - 7.9 mg/L), respectively. After a median follow-up of 7 months (2 - 16 months), 13 (93%) of patients remain on study;one patient died (7%) due from complications from a presumed bacterial (COVID19-negative) pneumonia after 2 months on therapy. The estimated one-year PFS and OS for the cohort is 92.8 %. Seven patients were evaluable for response assessment after 8 months of therapy. No patient has yet discontinued therapy. All patients achieved a PR (one patient with undetectable minimal residual disease/U-MRD in the bone marrow), accounting for an overall responsonse rate of 100%. The median levels of bone marrow infiltration by CLL cells, quantified by flow cytometry, declined from 83.6% (range: 54.3 - 94.0 %) at baseline to 4.1% (range, 0.0 - 63.3%, n=7, p<0.05, see figure) after 6 cycles of combination treatment. Sixty-four percent of patients completed all doses of obinotuzumab, 50% requiered a dose reduction of acalabrutinib to 100 mg per day due to adverse events (AE). Grade 33 AE were observed in 4 patients (29%), which included decreased neutrophil counts (n=2), syncope (n=1), and grade 5 lung infection (COVID19 not detected, n=1). The most frequently reported non-serious related AE (3 2 patients) were anemia (n=5 [36%]), decreased platelets counts (n=3 [21%]), bruising (n=3 [21%]), limbs edema (n=2 [15%]) and headache (n=2 [15%]). All these events were grade 1. Importantly, no bleeding or atrial fibrillation events were observed. 3285 (Figure Presented ) Summary/Conclusion: Our preliminary data indicate that combination therapy of acalabrutinib plus obinotuzumab induces remissions with a major reduction in bone marrow disease after 6 months of combination therapy. Longer treatment and follow-up is warranted to determine the durability of responses after therapy discontinuation.

Venetoclax, Obinutuzumab and Atezolizumab (PD-L1 Checkpoint Inhibitor) for First-Line Treatment for Patients with Chronic Lymphocytic Leukemia (CLL)

Background: Dysfunction of T cells, NK cells and other immune subsets is common in patients (pts) with CLL. Venetoclax (VEN), a BCL-2 inhibitor and obinutuzumab (OBIN), a CD20 monoclonal antibody (mAb) are approved for pts with CLL (Fischer, NEJM 2019). Atezolizumab, a PD-L1 checkpoint inhibitor (CPI), is approved for melanoma, lung cancer and other solid tumors. Preclinical studies showed synergy of VEN and CD20 mAb with CPI (Kohlhapp, Cancer Discovery 2021;Westin, Lancet Oncology 2014). Clinical studies showed activity of PD1 inhibition in pts with Richter's transformation, but not CLL (Ding, Blood 2017;Jain, ASH 2018). To our knowledge, no prior study has evaluated PD-L1 inhibition in pts with CLL, nor combined CPI, VEN and OBIN. We hypothesized that combined VEN, OBIN and atezolizumab will be synergistic. Methods: This is an investigator-initiated Phase II trial of combined VEN, OBIN and atezolizumab in pts with previously untreated CLL meeting 2008 IWCLL treatment criteria (NCT02846623). Eligibility criteria included age ≥18 years, adequate organ function (total bilirubin ≤1.5 x ULN, ALT and AST ≤2.5 x ULN, creatinine ≤1.5 x ULN). OBIN was given at a flat dose of 100mg IV Cycle (C)1 Day (D)1, 900 mg C1D2, 1000mg on C1D8, 1000mg on C1D15 and then 1000mg on C2-9 D1. Atezolizumab was given at a flat dose of 1680 mg IV (split over 2 days) on C1D3-4 and then C2-9D1-2. VEN was initiated at the start of C3 with the weekly dose-escalation (20mg daily to a target dose of 400mg daily) and continued daily until end of C14 (total 12 cycles of VEN). All pts stopped therapy at the end of C14. Response assessments were done with CT imaging and bone marrow aspirate/biopsy with MRD assessment (multi-color flow cytometry;sensitivity 10 -4) at the end of C2 (prior to VEN initiation), end of C6, end of C9, and end of C14. Results: From July 2019 to December 2020, a total of 26 pts were enrolled. The median age was 60 years (range, 21-74). The baseline characteristics are shown in Table 1. A total of 19/26 (73%) had unmutated IGHV gene. Though the study did not restrict pts with del(17p) or mutated TP53, no pt in the current cohort had del(17p)/ mutated TP53. A total of 14 (54%) pts had a baseline lymph node >5cm. The median follow-up is 13.3 months. One pt came off study in C1 (details below). A total of 25 pts initiated VEN. The TLS risk categories at the start of C1 were high (n=9, 36%), medium (n=12, 48%), and low (n=4, 16%). After 2 cycles of OBIN and atezolizumab (prior to VEN initiation), the majority of pts had downgrading of TLS risk category [high (n=2, 8%), medium (n=3, 12%), and low (n=20, 80%)]. After C6 (about 3 cycles of VEN 400mg daily), bone marrow undetectable (U)-MRD rate was 19/25 (76%);4/25 (16%) had low+ MRD and 2/25 (8%) had high+ MRD. After C9 (about 6 cycles of VEN 400mg daily), among the 21 pts (4 pts have not reached this time-point), the bone marrow U-MRD rate was 18/21 (86%);2/21 (10%) had low+ MRD and 1/21 (5%) had high+ MRD. A total of 14 pts completed C14 (9 pts have not reached this time-point;2 pts came off study prior to completing C14, details below);13/14 (93%) achieved bone marrow U-MRD and 1/14 (7%) has low+ MRD. No patient had disease progression or MRD relapse so far. One pt died (details below). Three pts came off study (one developed retroperitoneal hematoma after receiving enoxaparin for DVT in C1;one developed CPI-induced colitis and removed from the study in C10;one died from COVID-19 pneumonia in C14 while in bone marrow U-MRD remission). Grade 3-4 neutropenia occurred in 14/26 (54%) pts. Grade 3 thrombocytopenia occurred in 5/26 (19%) pts;no pt had G4 thrombocytopenia. A total of 4 pts developed CPI-induced toxicities (colitis, G3, n=1;mucositis, G3, n=1;nephritis, G2, n=1;myositis, G2, n=1). A total of 10/25 (40%) pts had dose reduction of VEN, the majority due to neutropenia. Atezolizumab was discontinued early in 3 pts due to CPI-induced toxicities. Laboratory correlative studies including scRNAseq and CyTOF are ongoing. Conclusions: Treatment with combined VE , OBIN and atezolizumab leads to high rate of early U-MRD remission with 76% bone marrow U-MRD remission at the end of C6 (about 3 cycles of VEN 400mg daily). Four pts had CPI-induced toxicities. The enrollment in this trial continues and updated data and correlative studies will be presented at the ASH meeting. [Formula presented] Disclosures: Jain: Pfizer: Research Funding;Bristol Myers Squibb: Honoraria, Research Funding;Precision Biosciences: Honoraria, Research Funding;Aprea Therapeutics: Research Funding;AstraZeneca: Honoraria, Research Funding;Servier: Honoraria, Research Funding;Incyte: Research Funding;Pharmacyclics: Research Funding;Genentech: Honoraria, Research Funding;AbbVie: Honoraria, Research Funding;TG Therapeutics: Honoraria;Janssen: Honoraria;Beigene: Honoraria;Fate Therapeutics: Research Funding;Adaptive Biotechnologies: Honoraria, Research Funding;Cellectis: Honoraria, Research Funding;ADC Therapeutics: Honoraria, Research Funding. Ferrajoli: Janssen: Other: Advisory Board;AstraZeneca: Other: Advisory Board, Research Funding;BeiGene: Other: Advisory Board, Research Funding. Yilmaz: Daiichi-Sankyo: Research Funding;Pfizer: Research Funding. Thompson: AbbVie: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding;Gilead: Other: Institution: Advisory/Consultancy, Honoraria;Janssen: Consultancy, Honoraria;Pharmacyclics: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding;Adaptive Biotechnologies: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding, Expert Testimony;Genentech: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding;Amgen: Other: Institution: Honoraria, Research Grant/Funding. Konopleva: Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights;Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights;Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding;KisoJi: Research Funding;Stemline Therapeutics: Research Funding;Sanofi: Other: grant support, Research Funding;Rafael Pharmaceuticals: Other: grant support, Research Funding;AstraZeneca: Other: grant support, Research Funding;Cellectis: Other: grant support;F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support;Calithera: Other: grant support, Research Funding;Ascentage: Other: grant support, Research Funding;Ablynx: Other: grant support, Research Funding;Genentech: Consultancy, Honoraria, Other: grant support, Research Funding;Forty Seven: Other: grant support, Research Funding;AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding;Agios: Other: grant support, Research Funding. Neelapu: Takeda Pharmaceuticals and related to cell therapy: Patents & Royalties;Kite, a Gilead Company, Bristol Myers Squibb, Merck, Poseida, Cellectis, Celgene, Karus Therapeutics, Unum Therapeutics (Cogent Biosciences), Allogene, Precision BioSciences, Acerta and Adicet Bio: Research Funding;Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene, Kuur, Incyte, Precision BioSciences, Legend, Adicet Bio, Calibr, and Unum Therapeutics: Other: personal fees;Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene Therapeutics, Cell Medica/Kuur, Incyte, Precision Biosciences, Legend Biotech, Adicet Bio, Calibr, Unum Therapeutics and Bluebird Bio: Honoraria. Takahashi: Symbio Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees;Celgene/BMS: Consultancy;Novartis: Consultancy;GSK: Consultancy. Burger: TG Therapeutics: Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau;Beigene: Research Funding, Speakers Bureau;Novartis: Other: Travel/Accommodations/Expenses, Speakers Bureau;Pharmacyclics LLC: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau;Gilead: Consultancy, Other: Travel/Accommodations/Expenses, Rese rch Funding, Speakers Bureau;AstraZeneca: Consultancy;Janssen: Consultancy, Other: Travel/Accommodations/Expenses, Speakers Bureau. Khoury: Stemline Therapeutics: Research Funding;Kiromic: Research Funding;Angle: Research Funding. Kantarjian: Jazz: Research Funding;NOVA Research: Honoraria;Novartis: Honoraria, Research Funding;KAHR Medical Ltd: Honoraria;Precision Biosciences: Honoraria;Amgen: Honoraria, Research Funding;Astra Zeneca: Honoraria;AbbVie: Honoraria, Research Funding;Ipsen Pharmaceuticals: Honoraria;Pfizer: Honoraria, Research Funding;Astellas Health: Honoraria;Aptitude Health: Honoraria;Taiho Pharmaceutical Canada: Honoraria;Immunogen: Research Funding;Daiichi-Sankyo: Research Funding;BMS: Research Funding;Ascentage: Research Funding. Wierda: Karyopharm: Research Funding;Miragen: Research Funding;Acerta Pharma Inc.: Research Funding;Cyclacel: Research Funding;Oncternal Therapeutics, Inc.: Research Funding;Pharmacyclics LLC, an AbbVie Company: Research Funding;Sunesis: Research Funding;Juno Therapeutics: Research Funding;Gilead Sciences: Research Funding;AstraZeneca: Research Funding;Genentech: Research Funding;Loxo Oncology, Inc.: Research Funding;Janssen: Research Funding;Xencor: Research Funding;GSK/Novartis: Research Funding;KITE Pharma: Research Funding;Genzyme Corporation: Consultancy;AbbVie: Research Funding. OffLabel Disclosure: Atezolizumab is not approved for CLL

Combined Ibrutinib and Venetoclax for First-Line Treatment of Patients with Chronic Lymphocytic Leukemia (CLL): Focus on Long-Term MRD Results

Background: Ibrutinib (IBR) and venetoclax (VEN) combination is a highly effective therapy for patients (pts) with CLL (Jain, NEJM 2019;Wierda, ASH 2020;Kater, EHA 2021). We previously reported results of the first-line cohort of a phase II trial of combined IBR and VEN for high-risk pts with CLL (Jain, NEJM 2019;Jain, JAMA Oncology 2021). Here we report updated data for these pts with focus on MRD. Methods: Pts with previously untreated CLL meeting IWCLL treatment criteria were enrolled. All pts had at least one high-risk feature: del(17p), mutated TP53, del(11q), unmutated IGHV, or age ≥65 years (yrs). Pts received IBR 420 mg daily for 3 cycles followed by addition of VEN (weekly dose-escalation to 400mg daily). Combined therapy was given for 24 cycles (28 days/cycle). Pts with bone marrow (BM) undetectable MRD (U-MRD) (flow cytometry;sensitivity 10 -4) at 24 cycles of combined therapy discontinued both VEN and IBR;MRD+ pts continued IBR. A trial amendment allowed an additional 12 cycles of combined VEN and ibrutinib for pts who remained BM MRD+ after Cycle 24. Response assessments were performed using BM and CT imaging studies (2008 IWCLL criteria). U-MRD was defined as <0.01%;low MRD+ 0.01% to <1%;high MRD+ ≥1%. Progression-free survival (PFS) was assessed as the time from the start of study drug to CLL progression, Richter transformation, or death from any cause. Blood MRD was monitored every 6 months in pts off treatment or on ibrutinib monotherapy beyond 24 cycles of combined treatment. Results: A total of 80 pts were enrolled. Baseline characteristics are shown in Table 1. The median follow-up was 44.1 months. Five pts came off study during 1 st 3 cycles of IBR monotherapy;75 pts initiated VEN. We previously reported that after 12 cycles of the combination, 45/80 (56%) achieved BM U-MRD remission;24/80 (30%) were BM MRD-positive (low MRD+, n=19;high MRD+, n=5). After 24 cycles of the combination, 53/80 (66%) achieved BM U-MRD remission;14/80 (17%) were BM MRD+ (low MRD+, n=13;high MRD+, n=1). Overall, 60/80 (75%) achieved BM U-MRD as the best response. Updated PFS is provided in Figure 1. Of the 53 pts who were BM U-MRD at the end of cycle 24 of the combination, 52 pts had a subsequent blood MRD assessment done in follow-up (1 missed due to COVID-19);51/53 discontinued all therapy, 2 pts continued IBR per treatment physician discretion. With a median time of 18.4 months post Cycle 24, 8 pts had recurrence of blood MRD (defined as MRD ≥ 0.01% in 2 consecutive visits) in follow-up with 1 pt with CLL progression. The sole pt with CLL progression had mutated IGHV with del(11q) and NOTCH1 mutation. The pt had delayed achievement of BM U-MRD with the pt achieving U-MRD for the first time at the end of Cycle 24 of combined therapy. She was noted to have disease progression 22 months off therapy;BTK or PLCG2 mutation were not detected and the patient is currently in clinical remission on acalabrutinib. The time to MRD conversion for these 53 pts is shown in Figure 2. There were 14 pts who were BM MRD+ at the end of cycle 24 of the combination (low MRD+, n=13;high MRD+, n=1). The only pt with high-MRD+ at end of cycle 24 was noted to have Richter transformation at that time. The remaining 13 pts (all low MRD+ in BM, range 0.01-0.56%) continued IBR monotherapy. With a recent trial amendment, MRD+ pts after Cycle 24 could get 12 additional cycles of venetoclax;9/13 pts have resumed VEN. 6/9 pts have achieved U-MRD remission. 2 pts had Richter transformation and 3 pts have died (Jain, JAMA Oncology 2021). Conclusions: We report long term follow-up of combined IBR and VEN in first-line CLL. Remissions were durable with some pts having recurrence of blood MRD in follow-up, which may be an early indicator of relapse. In a small subset of the pts with BM MRD+ disease at 24 cycles of combined therapy, additional VEN appears to lead to U-MRD remission in majority of the pts. Whether this will lead to improved long-term PFS remains to be determined. [Formula presented] Disclosures: Jain: TG Therapeutics: Honoraria;Beigene: Honoraria;Janssen: Honoraria;Fate Therapeutics: Research Funding;Aprea Therapeutics: Research Funding;Precision Biosciences: Honoraria, Research Funding;Incyte: Research Funding;Adaptive Biotechnologies: Honoraria, Research Funding;Cellectis: Honoraria, Research Funding;ADC Therapeutics: Honoraria, Research Funding;Servier: Honoraria, Research Funding;Pfizer: Research Funding;Bristol Myers Squibb: Honoraria, Research Funding;AstraZeneca: Honoraria, Research Funding;Genentech: Honoraria, Research Funding;AbbVie: Honoraria, Research Funding;Pharmacyclics: Research Funding. Thompson: AbbVie: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding;Amgen: Other: Institution: Honoraria, Research Grant/Funding;Genentech: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding;Adaptive Biotechnologies: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding, Expert Testimony;Pharmacyclics: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding;Janssen: Consultancy, Honoraria;Gilead: Other: Institution: Advisory/Consultancy, Honoraria. Ferrajoli: BeiGene: Other: Advisory Board, Research Funding;Janssen: Other: Advisory Board;AstraZeneca: Other: Advisory Board, Research Funding. Burger: Novartis: Other: Travel/Accommodations/Expenses, Speakers Bureau;TG Therapeutics: Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau;Janssen: Consultancy, Other: Travel/Accommodations/Expenses, Speakers Bureau;Beigene: Research Funding, Speakers Bureau;Pharmacyclics LLC: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau;Gilead: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau;AstraZeneca: Consultancy. Borthakur: GSK: Consultancy;ArgenX: Membership on an entity's Board of Directors or advisory committees;University of Texas MD Anderson Cancer Center: Current Employment;Protagonist: Consultancy;Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees;Astex: Research Funding;Ryvu: Research Funding;Takeda: Membership on an entity's Board of Directors or advisory committees. Takahashi: Symbio Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees;Novartis: Consultancy;Celgene/BMS: Consultancy;GSK: Consultancy. Sasaki: Daiichi-Sankyo: Membership on an entity's Board of Directors or advisory committees;Pfizer: Membership on an entity's Board of Directors or advisory committees;Novartis: Consultancy, Research Funding. Kadia: Cellonkos: Other;Aglos: Consultancy;Dalichi Sankyo: Consultancy;AbbVie: Consultancy, Other: Grant/research support;BMS: Other: Grant/research support;Amgen: Other: Grant/research support;Cure: Speakers Bureau;Jazz: Consultancy;Genentech: Consultancy, Other: Grant/research support;Liberum: Consultancy;Novartis: Consultancy;Pfizer: Consultancy, Other;Pulmotech: Other;Sanofi-Aventis: Consultancy;AstraZeneca: Other;Astellas: Other;Genfleet: Other;Ascentage: Other. Konopleva: Sanofi: Other: grant support, Research Funding;Cellectis: Other: grant support;Calithera: Other: grant support, Research Funding;KisoJi: Research Funding;Agios: Other: grant support, Research Funding;Ascentage: Other: grant support, Research Funding;AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding;Ablynx: Other: grant support, Research Funding;Stemline Therapeutics: Research Funding;Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding;AstraZeneca: Other: grant support, Research Funding;Rafael Pharmaceuticals: Other: grant support, Research Funding;Genentech: Consultancy, Honoraria, Other: grant support, Research Funding;F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support;Forty Seven: Other: grant support, Research Funding;Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights;Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights. Alvarado: BerGenBio: Research Funding;Jazz Pharmaceuticals: Research Funding;Astex Pharmaceuticals: Research Funding;Sun Pharma: Consultancy, Research Funding;MEI Pharma: Research Funding;FibroGen: Research Funding;Daiichi-Sankyo: Research Funding;CytomX Therapeutics: Consultancy. Yilmaz: Pfizer: Research Funding;Daiichi-Sankyo: Research Funding. DiNardo: Notable Labs: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees;Novartis: Honoraria;Takeda: Honoraria;Celgene, a Bristol Myers Squibb company: Honoraria, Research Funding;Forma: Honoraria, Research Funding;AbbVie: Consultancy, Research Funding;GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees;Bristol Myers Squibb: Honoraria, Research Funding;ImmuneOnc: Honoraria, Research Funding;Agios/Servier: Consultancy, Honoraria, Research Funding;Foghorn: Honoraria, Research Funding. Bose: Kartos Therapeutics: Honoraria, Research Funding;Sierra Oncology: Honoraria;Novartis: Honoraria;Constellation Pharmaceuticals: Research Funding;NS Pharma: Research Funding;Celgene Corporation: Honoraria, Research Funding;Blueprint Medicines: Honoraria, Research Funding;Pfizer: Research Funding;Promedior: Research Funding;Astellas: Research Funding;Incyte Corporation: Honoraria, Research Funding;BMS: Honoraria, Research Funding;CTI BioPharma: Honoraria, Research Funding. Pemmaraju: Blueprint Medicines: Consultancy;LFB Biotechnologies: Consultancy;Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding;ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees;Dan's House of Hope: Membership on an entity's Board of Directors or advisorycommittees;Roche Diagnostics: Consultancy;MustangBio: Consultancy, Other;Affymetrix: Consultancy, Research Funding;Samus: Other, Research Funding;ImmunoGen, Inc: Consultancy;ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees;Aptitude Health: Consultancy;Plexxicon: Other, Research Funding;Springer Science + Business Media: Other;Protagonist Therapeutics, Inc.: Consultancy;HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees;Clearview Healthcare Partners: Consultancy;Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding;CareDx, Inc.: Consultancy;Sager Strong Foundation: Other;Daiichi Sankyo, Inc.: Other, Research Funding;Incyte: Consultancy;Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding;Bristol-Myers Squibb Co.: Consultancy;DAVA Oncology: Consultancy;Pacylex Pharmaceuticals: Consultancy;Celgene Corporation: Consultancy;Cellectis S.A. ADR: Other, Research Funding. Jabbour: Amgen, AbbVie, Spectrum, BMS, Takeda, Pfizer, Adaptive, Genentech: Research Funding. Wang: Stemline Therapeutics: Honoraria. Kantarjian: Taiho Pharmaceutical Canada: Honoraria;Precision Biosciences: Honoraria;Immunogen: Research Funding;Daiichi-Sankyo: Research Funding;Jazz: Research Funding;BMS: Research Funding;AbbVie: Honoraria, Research Funding;Pfizer: Honoraria, Research Funding;Novartis: Honoraria, Research Funding;NOVA Research: Honoraria;KAHR Medical Ltd: Honoraria;Ipsen Pharmaceuticals: Honoraria;Astra Zeneca: Honoraria;Astellas Health: Honoraria;Aptitude Health: Honoraria;Amgen: Honoraria, Research Funding;Ascentage: Research Funding. Wierda: Juno Therapeutics: Research Funding;AstraZeneca: Research Funding;Xencor: Research Funding;Janssen: Research Funding;Loxo Oncology, Inc.: Research Funding;Cyclacel: Research Funding;Oncternal Therapeutics, Inc.: Research Funding;Miragen: Research Funding;KITE Pharma: Research Funding;Sunesis: Research Funding;Gilead Sciences: Research Funding;Acerta Pharma Inc.: Rese rch Funding;Pharmacyclics LLC, an AbbVie Company: Research Funding;Karyopharm: Research Funding;Genentech: Research Funding;GSK/Novartis: Research Funding;Genzyme Corporation: Consultancy;AbbVie: Research Funding. OffLabel Disclosure: The combination of ibrutinib and venetoclax is not FDA approved

Apport de la microscopie 2-photon (M2P) dans l’exploration des mécanismes immunitaires après infection par le virus de la grippe d’un modèle murin

Introduction Même si depuis 18 mois, le SARS-Cov2 a fait disparaître toute trace des virus respiratoires hivernaux historiques, les virus de la grippe, responsables de plusieurs pandémies durant le 20e siècle et d’une mortalité non négligeable, restent un sujet d’étude d’actualité. De nombreux travaux ont étudié la réaction immune innée post infection grippale mais sous un angle quantitatif en terme cellulaire et cytokinique. Le développement de technologie de microscopie moderne permettant d’étudier un organe entier en profondeur en conservant une excellente résolution mérite d’être évaluée. Peu de données sont disponibles sur l’intérêt de la M2P dans l’exploration du poumon et aucune sur son intérêt dans l’exploration des mécanismes immunitaires post infection grippale. Le but de ce travail est donc d’étudier l’intérêt de la M2P dans l’exploration des dommages structurales pulmonaires et du recrutement cellulaire après infection par le virus de la grippe d’un modèle murin. Méthodes Nous avons infecté des souris C57bl/6J génétiquement modifiées, dont les cellules CD11C+ expriment une protéine fluorescente jaune, par voie inhalée avec Influenzavirus (adapté à la souris) auquel la protéine NS1 a été couplée à une protéine fluorescente rouge. En plus de cette fluorescente endogène, nous avons utilisé un Ac anti F4/80 couplé à une protéine fluorescente bleue pour visualiser les macrophages. Nous avons ensuite étudié les poumons à jour 1, 2, 3, 4, 5 post infection en cytométrie en flux pour quantification cellulaire, dosage cytokinique et exploration en M2P. Nous avons développé un protocole d’imagerie M2P Intravital ex vivo pour évaluer le trafficking cellulaire. Résultats M2P a permis de mettre en évidence des dommages structuraux pulmonaires, de localiser les sites infectés, d’étudier les interactions cellulaires et d’étudier l’évolution dans le temps post infection. Ces résultats enrichissent et complètent les données quantitatives déjà publiées (cytométrie) et permettent d’étudier dans le temps la cinétique et la localisation des lésions et du recrutement cellulaire. De plus, le protocole d’imagerie Intravitale ex vivo a été mis au point. Conclusion En complément des analyses usuelles (cytométrie en flux, dosage cytokines…), M2P est donc une technologie pertinente et prometteuse dans les études précliniques en infectiologie respiratoire nous a permis de décrire une base physiopathologique de référence pour de futures études notamment d’impact des traitements anti-viraux ou anti-inflammatoires.