McCarthy, Colin

Ibrutinib-based therapies are costly and require continuous administration. We hypothesized combining BTK inhibition with anti-CD20 monoclonal antibodies would yield deep remissions allowing discontinuation. We enrolled 32 therapy-naïve CLL patients to receive ibrutinib plus obinutuzumab, followed by single-agent ibrutinib. Patients could discontinue ibrutinib after 36 months with sustained complete response (CR). We evaluated treatment safety, efficacy, and outcomes after ibrutinib discontinuation. The overall response rate was 100%, 28% achieved a CR, and 12.5% achieved bone marrow undetectable minimal residual disease. At a three-year median follow-up, 91% remain in remission with 100% overall survival. Five patients in sustained CR stopped ibrutinib and have not progressed. Eight non-CR patients discontinued for other reasons, with only two progressing. The treatment was safe, with a lower IRR rate. All patients responded to treatment with longer time-to-progression after discontinuation of ibrutinib. Our data support the evaluation of ibrutinib discontinuation strategies in more extensive clinical trials (https://Clinicaltrials.gov Identifier https://clinicaltrials.gov/ct2/show/NCT02315768).

Abstract Ibrutinib-based therapies are costly and require continuous administration. We hypothesized combining BTK inhibition with anti-CD20 monoclonal antibodies would yield deep remissions allowing discontinuation. We enrolled 32 therapy-naïve CLL patients to receive ibrutinib plus obinutuzumab, followed by single-agent ibrutinib. Patients could discontinue ibrutinib after 36 months with sustained complete response (CR). We evaluated treatment safety, efficacy, and outcomes after ibrutinib discontinuation. The overall response rate was 100%, 28% achieved a CR, and 12.5% achieved bone marrow undetectable minimal residual disease. At a three-year median follow-up, 91% remain in remission with 100% overall survival. Five patients in sustained CR stopped ibrutinib and have not progressed. Eight non-CR patients discontinued for other reasons, with only two progressing. The treatment was safe, with a lower IRR rate. All patients responded to treatment with longer time-to-progression after discontinuation of ibrutinib. Our data support the evaluation of ibrutinib discontinuation strategies in more extensive clinical trials.

Abstract Obinutuzumab-Gazyva (G) is an anti-CD20 monoclonal antibody that has shown better outcomes in patients (pts) with chronic lymphocytic leukemia and low-grade lymphoma (Goede 2014, Marcus 2017). However, one limitation for its use when compared to Rituximab is the presence of significantly more frequent and more severe infusion related reactions (IRR). Strategies to mitigate this significant adverse event are needed particularly to allow a safer administration of this antibody to elderly pts or those with existing comorbidities. We have observed a reduction of G-induced IRR in previously untreated CLL pts that are enrolled on a phase Ib/II clinical trial (NCT02315768) that combines G with the Bruton's tyrosine kinase inhibitor, ibrutinib (Ibr). Only 5 out of 23 pts treated have developed IRR (Grade 1-2, 17% and Grade 3, 4%). This rate of IRR is much lower as compared with rates previously reported (all grades: 65%, grade 3-4: 20% - Goede 2014), (all grades: 92%, grade 3-4: 26.3% - Freeman,2015). Moreover, there were no pts that require permanent discontinuation of G due to IRR. To understand the biology of this beneficial effect of Ibr, we performed serial cytokine measurements on plasma samples from 23 pts enrolled in this study at different time points during the first week of combined treatment (Cycle 1 prior to the first infusion of G and post G infusion on Day 1, Day 2 and Day 8) - Figure 1. We developed a multiplex assay (Luminex) to measure 7 different cytokines previously reported to be involved in IRR (IFN-g, IL-10, IL6, IL8, CCL3/MIP1-a, CCL4/MIP1-band TNF-a). Standards were set up in duplicate yielding curves from 3.2 pg/ml to 10.000 pg/ml. Assays were performed according to manufacturer's instructions, with undiluted samples and overnight agitated incubation at 4 °C. We identified the maximum peak of cytokine levels post G infusion and compared those values with the baseline cytokine profile obtained prior to the first G infusion on Cycle 1 Day 1. The majority of pts (22 out of 23) showed cytokines maximum peaks in the middle of G-infusion during Cycle 1 Day 1 and this correlated with the onset of IRR associated symptoms in those pts that reacted to G. With the exception of IL-6, we observed statistically higher post vs. pre G infusion levels of TNF-a(p=0.0012), IFN-g(p=<0.0001), CCL3 (p=0.0458), CCL4 (p=<0.0001), IL-8 (p=<0.0001), and IL-10 (p=<0.0001) even in pts that did not develop IRR. However, the post infusion peak levels of TNF-a(p=0.0043), IFN-g(p=0.0457) and CCL3 (p=0.0460) were significantly higher in pts with IRR compared to those that had no IRR. Baseline levels prior to G infusion of TNF-a(p=0.0495) and IFN-g(p=0.0301) were higher in IRR pts, suggesting a possible predictive role in the development of IRR. Figure 1. Our study shows that concurrent administration of Ibr (Initiated on Cycle 1 Day 1 with pre-medications) and G shows a beneficial effect decreasing the rates of IRR (Amaya-Chanaga, 2016). All pts showed a significant increase of cytokine levels post G infusion with IL-6 levels being the exception. When we compared post G infusion cytokine levels, we observed that IRR-pts had a significant increase in TNF-a, IFN-g, and CCL3 suggesting a role of these cytokines in the clinical manifestations associated with IRR. In addition, higher levels of TNF-a and IFN-g, at baseline prior to G infusion appear to be predictive of the development of IRR. Even though our sample size is small, our observations provide additional insights into the biology of G associated IRR and how to decrease effectively those adverse events using Ibr while preserving the immune function needed for the activity of this monoclonal antibody. In addition, Ibr induced modulation of signaling through the B cell receptor and patterns of cytokine release might be efficacious in preventing other monoclonal antibody IRR as well as those reactions observed in pts that receive adoptive cellular therapy (i.e. CART cell treatment). Disclosures Choi: AbbVie, Inc: Consultancy, Speakers Bureau; Gilead: Speakers Bureau; Genentech: Speakers Bureau; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Rigel: Consultancy. Amaya-Chanaga:AbbVie: Equity Ownership, Other: Research performed while employed as an investigator of this study at UCSD. Review and approval of abstract performed while employed at Pharmacyclics, LLC, an AbbVie Company.; Pharmacyclics, an AbbVie Company: Employment, Other: Research performed while employed as an investigator of this study at UCSD. Review and approval of abstract performed while employed at Pharmacyclics, LLC, an AbbVie Company.. Kipps:Celgene: Consultancy; F. Hoffmann-La Roche Ltd: Consultancy, Research Funding; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Verastem: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech Inc: Consultancy, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Verastem: Membership on an entity's Board of Directors or advisory committees. Castro:F. Hoffmann-La Roche: Consultancy; Genentech, Inc: Consultancy; Pharmacyclics, LLC, an AbbVie Company:: Consultancy.

Abstract Standard treatment for patients with chronic lymphocytic leukemia (CLL) is rapidly evolving and gradually has incorporated the combined use of monoclonal antibodies (mAbs) and targeted therapy with small molecules. Single agent Ibrutinib (Ibr), a first-in-class BTK inhibitor, is effective in previously untreated patients including those that are older than 65 or considered unfit to receive chemotherapy-based combinations. The complete response rate in patients receiving single agent Ibr is relatively low (overall response rate of 86% and complete response of 4% based on 2008 iwCLL criteria), though most patients have durable remissions. The combination of Ibr with mAbs like Obinutuzumab-Gazyva (G), a third-generation anti-CD20 mAb, can ameliorate the Ibr-induced lymphocytosis and increase the overall and complete response rates. Accordingly, we initiated an open-label phase Ib/II clinical study of Ibr in combination with G for first-line therapy of previous untreated pts with CLL. The study completed enrollment of 32 previously untreated patients with CLL. Patients received G administered based on FDA dosing recommendations for 6 cycles (28 days/cycle) and Ibr 420mg po (1-3 hours before starting G infusion), and daily for up to 3 years. All patients received prophylactic medications. Patients were assessed for response by 2008 iwCLL criteria two months after completion of G, as the primary efficacy endpoint. The median age of the patients was 65 (range: 46-78) years. 84% of the patients had a CIRS >6, 45% had a Rai stage III-IV and 19% had an ECOG performance ≤2. The median baseline absolute lymphocyte count (ALC) was 79x103/mm3(range: 1.4-412.4). Patients showed the following FISH/cytogenetic abnormalities: del(13q) in 55%, trisomy 12 in 23% and del(11q) in 19%. Only 2 (6%) of these patients showed del(17p). From the patients with IGVH mutational status available (n=17), 11 (65%) were unmutated (>98% homology). Most adverse events (AEs) were grade 1-2 (74%). Six patients (19%) had grade 1-2 G-infusion-related reaction (IRR) and only one patient (3%) showed grade 3 IRR (without the need for G discontinuation). We observed neutropenia (all grades: 52%, grade 3-4: 23%), thrombocytopenia (all grades: 71%, grade 3-4: 19%) and anemia (all grades: 26%). There were no cases of febrile neutropenia. Two patients (6%) had grade 1 bleeding (one patient with asymptomatic lower gastrointestinal bleeding and the second patient with epistaxis) that resolved spontaneously without requirement of blood transfusion or study treatment discontinuation. Two patients (6%) developed pneumonia, one was community-acquired pneumonia requiring inpatient treatment with IV antibiotics; the study treatment was held until resolution of symptoms and re-initiated at full dose. The most frequent non-hematological AEs were diarrhea, transaminitis, hyperbilirubinemia, hyperglycemia, and electrolyte alterations (grade 1-2). Three patients (9%) discontinued Ibr due to atrial fibrillation grade 1 (n=1), rash and headaches grade 2 (n=1), and persistent grade 4 thrombocytopenia (n=1). Twenty-three patients were evaluable for response assessment by 2008 iwCLL criteria (median follow-up of 11 months). 84% of the patients showed a rapid decrease in ALC from baseline during the first cycle of treatment and only four patients (13%) required more than 3 cycles of treatment to achieve an ALC response. The overall response rate was 100%. The majority of pts had a partial response and six of 23 evaluable patients (26%) achieved a complete remission with detectable Minimal Residual Disease in the bone marrow by multiparametric flow cytometry. In summary, Ibr-G combination has been generally well tolerated. AEs have been consistent with the known safety profiles of Ibr and G individually. The patients that discontinued Ibr remain in follow-up without disease progression. 100% of evaluable patients achieved response after 6 months of combination therapy, and 26% of patients met CR criteria. One important finding thus far has been a very low rate of IRR, (19% grade 1-2 and 3% grade 3-4), suggesting that Ibr can strongly mitigate the incidence and severity of G associated IRR. Disclosures Choi: AbbVie, Inc: Consultancy, Speakers Bureau; Rigel: Consultancy; Gilead: Speakers Bureau; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Genentech: Speakers Bureau. Amaya-Chanaga:AbbVie: Equity Ownership, Other: Research performed while employed as an investigator of this study at UCSD. Review and approval of abstract performed while employed at Pharmacyclics, LLC, an AbbVie Company.; Pharmacyclics, an AbbVie Company: Employment, Other: Research performed while employed as an investigator of this study at UCSD. Review and approval of abstract performed while employed at Pharmacyclics, LLC, an AbbVie Company.. Kipps:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Research Funding; Celgene: Consultancy; Verastem: Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Research Funding; Genentech Inc: Consultancy, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Verastem: Membership on an entity's Board of Directors or advisory committees. Castro:F. Hoffmann-La Roche: Consultancy; Genentech, Inc: Consultancy; Pharmacyclics, LLC, an AbbVie Company:: Consultancy.