Kenderian, Saad Sirop

Abstract The receptor tyrosine kinase AXL is a member of the TYRO3, AXL, and proto-oncogene tyrosine-protein kinase MER family and plays pleiotropic roles in cancer progression. AXL is expressed in immunosuppressive cells, which contributes to decreased efficacy of immunotherapy. Therefore, we hypothesized that AXL inhibition could serve as a strategy to overcome resistance to chimeric antigen receptor T (CAR T)–cell therapy. To test this, we determined the impact of AXL inhibition on CD19-targeted CAR T (CART19)–cell functions. Our results demonstrate that T cells and CAR T cells express high levels of AXL. Specifically, higher levels of AXL on activated Th2 CAR T cells and M2-polarized macrophages were observed. AXL inhibition with small molecules or via genetic disruption in T cells demonstrated selective inhibition of Th2 CAR T cells, reduction of Th2 cytokines, reversal of CAR T-cell inhibition, and promotion of CAR T-cell effector functions. AXL inhibition is a novel strategy to enhance CAR T-cell functions through two independent, but complementary, mechanisms: targeting Th2 cells and reversing myeloid-induced CAR T-cell inhibition through selective targeting of M2-polarized macrophages.

SummaryPatients with chronic lymphocytic leukaemia (CLL) disease progression on ibrutinib or after sequential ibrutinib and venetoclax‐based treatments (double‐refractory) have poor outcomes. In this retrospective study, we analysed outcomes with combined ibrutinib and venetoclax treatment in these groups of patients. The median treatment‐free and overall survival for 22 patients with prior progression on ibrutinib (venetoclax‐naïve) were 23.7 and 47.1 months respectively. In 11 patients with double‐refractory CLL, the median treatment‐free and overall survival were 11.2 and 27.0 months respectively. The combination of ibrutinib and venetoclax may help bridge the current gap in options for patients with disease refractory to the most commonly used novel agents.

AbstractMonoclonal B‐cell lymphocytosis (MBL) and chronic lymphocytic leukemia (CLL) are clonal B‐cell disorders associated with an increased risk of infections and impaired vaccination responses. We investigated the immunogenicity of recombinant zoster vaccine (RZV) in these patients. Individuals with MBL/untreated CLL and Bruton tyrosine kinase inhibitor (BTKi)‐treated CLL patients were given two doses of RZV separated by 2 months. Responses assessed at 3 and 12 months from the first dose of RZV by an anti‐glycoprotein E ELISA antibody assay and by dual‐color Interferon‐γ and Interleukin‐2FLUOROSPOT assays were compared to historic controls matched by age and sex. About 62 patients (37 MBL/untreated CLL and 25 BTKi‐treated CLL) were enrolled with a median age of 68 years at vaccination. An antibody response at 3 months was seen in 45% of participants, which was significantly lower compared to historic controls (63%, p = .03). The antibody response did not significantly differ between MBL/untreated CLL and BTKi‐treated CLL (51% vs. 36%, respectively, p = .23). The CD4+ T‐cell response to vaccination was significantly lower in study participants compared to controls (54% vs. 96%, p < .001), mainly due to lower responses among BTKi‐treated patients compared to untreated MBL/CLL (32% vs. 73%, p = .008). Overall, only 29% of participants achieved combined antibody and cellular responses to RZV. Among participants with response assessment at 12 months (n = 47), 24% had antibody titers below the response threshold. Hypogammaglobulinemia and BTKi therapy were associated with reduced T‐cell responses in a univariate analysis. Strategies to improve vaccine response to RZV among MBL/CLL patients are needed.

AbstractTransplant‐associated thrombotic microangiopathy (TA‐TMA) has a wide range of presentations after hematopoietic stem‐cell transplantation (HSCT). We retrospectively studied the risk factors and outcomes of patients with early (≤day 100) and late (>day 100) TA‐TMA. Among the 1451 HSCT recipients, early TA‐TMA occurred in 45 (3.1%) patients at a median of 27 (3‐91) days, and late TA‐TMA in 39 (2.7%) patients at a median of 303 (122‐2595) days. Patients with early TA‐TMA were more likely to have high blood calcineurin‐inhibitor levels (P < .001) and acute graph‐vs‐host disease (GVHD, P < .001), while late TMA patients were more likely to have chronic GVHD (P < .001). The estimated median overall survival after onset of TMA for the entire cohort was 6 months. The estimated median overall survival was not reached in patients with an improvement of TMA vs 2 months in patients with no improvement (P < .001). In the early TMA group, older age (for every 10 years, HR 1.40; 95% CI 1.00‐1.94; P = .049) and bacterial infection (HR 2.42; 95% CI 0.98‐6.00; P = .056) were positively associated with mortality. Switching to MMF treatment (HR 0.40; 95% CI 0.16‐0.99; P = .047) and improvement of TMA (HR 0.08; 95% CI 0.03‐0.25; P < .001) were negatively associated with mortality in the multivariate analysis. In the late TMA group, the improvement of TMA was the only independent predictor associated with a lower risk of death (HR 0.05; 95% CI 0.02‐0.19; P < .001). Mortality rates in both early and late TMA remain unacceptably high. Future studies are needed for early diagnosis, trigger identifications, and use of targeted treatments.

Abstract To study the impact of dose modification and temporary interruption of ibrutinib in routine clinical practice, we conducted a retrospective study of consecutive CLL patients treated with ibrutinib outside the context of a clinical trial at Mayo Clinic, (Rochester, MN) from 11/2013 to 12/2017. Of 209 patients, 131 (74%) had unmutated IGHV , 38 (20%) had TP53 disruption, and 47 (22%) were previously untreated. A total of 87/209 (42%) patients started reduced dose ibrutinib (<420 mg daily; n = 43, physician preference; n = 33, concomitant medications; and n = 11, other). During 281 person‐years of treatment, 91/209 patients had temporary dose interruption (54%, nonhematologic toxicity; 29%, surgical procedures; 10%, hematologic toxicity; and 7%, other). After a median follow‐up of 24 months, the estimated median event‐free survival (EFS) was 36 months, and median overall survival (OS) was not reached. On multivariable analyses, temporary ibrutinib interruption (hazard ratio [HR]: 2.37, P = .006) and TP53 disruption at ibrutinib initiation (HR: 1.81, P = .048) were associated with shorter EFS, whereas only TP53 disruption (HR: 2.38, P = .015) was associated with shorter OS. Initial ibrutinib dose and dose modification during therapy did not appear to impact EFS or OS. These findings illustrate the challenges associated with continuous oral therapy with ibrutinib in patients with CLL.