Craig A. Portell

Postibrutinib outcomes in patients with mantle cell lymphoma

Despite unprecedented clinical activity in mantle cell lymphoma (MCL), primary and acquired resistance to ibrutinib is common. The outcomes and ideal management of patients who experience ibrutinib failure are unclear. We performed a retrospective cohort study of all patients with MCL who experienced disease progression while receiving ibrutinib across 15 international sites. Medical records were evaluated for clinical characteristics, pathological and radiological data, and therapies used pre- and postibrutinib. A total of 114 subjects met eligibility criteria. The median number of prior therapies was 3 (range, 0-10). The Mantle Cell Lymphoma International Prognostic Index (MIPI) scores at the start of ibrutinib were low, intermediate, and high in 46%, 31%, and 23% of patients, respectively. Of patients with available data prior to ibrutinib and postibrutinib, 34 of 47 and 11 of 12 had a Ki67 >30%. The median time on ibrutinib was 4.7 months (range 0.7-43.6). The median overall survival (OS) following cessation of ibrutinib was 2.9 months (95% confidence interval [CI], 1.6-4.9). Of the 104 patients with data available, 73 underwent subsequent treatment an average of 0.3 months after stopping ibrutinib with a median OS of 5.8 months (95% CI, 3.7-10.4). Multivariate Cox regression analysis of MIPI before postibrutinib treatment, and subsequent treatment with bendamustine, cytarabine, or lenalidomide failed to reveal any association with OS. Poor clinical outcomes were noted in the majority of patients with primary or secondary ibrutinib resistance. We could not identify treatments that clearly improved outcomes. Future trials should focus on understanding the mechanisms of ibrutinib resistance and on treatment after ibrutinib.

The Role of Infectious Agents, Antibiotics, and Antiviral Therapy in the Treatment of Extranodal Marginal Zone Lymphoma and Other Low-Grade Lymphomas

Opinion statementThere is strong evidence to corroborate the association with Helicobacter pylori (Hp) to gastric extranodal marginal zone lymphoma (ENMZL) and hepatitis C virus (HCV) to splenic/nodal marginal zone lymphoma. Koch’s postulates generally hold for these two associations and eradication of the infectious agent is well supported. Hp eradication (HPE) is recommended as front-line therapy for early stage gastric ENMZL regardless of Hp status. Complete response (CR) rate for Hp-negative patients is not as high as for Hp-positive patients; however, the benign nature of HPE and high rates of salvage allow this strategy to be safe while sparing some Hp-negative patients from systemic therapy or radiation. Similarly for HCV-seropositive patients, treatment with antivirals should be strongly considered as first-line for those who do not require immediate cytoreductive therapy or at some point even after completing chemoimmunotherapy. The controversy regarding the role for antibiotics is greatest for primary ocular adnexal lymphoma (POAL). Considering the low incidence of Chlamydia psittaci (Cp) infection with OAL and the challenges to reliably identifying Cp, we typically do not consider doxycycline in POAL treatment. Involved-field radiotherapy (IFRT) remains the treatment of choice for most with unilateral POAL. However, if reliable detection of Cp is available and Cp is identified, patients with unilateral low tumor stage POAL who do not require immediate radiotherapy could be considered for doxycycline as front-line treatment. Other infectious associations to indolent lymphomas have been made, including Borrelia borgdorferi (Bb) in cutaneous lymphoma and Campylobacter in immunoproliferative small intestinal disease (IPSID), but these associations are not as strong and primary treatment targeting the infectious agents is not recommended.

Implementation of a Model-Based Design in a Phase Ib Study of Combined Targeted Agents

In recent years, investigators have recognized the rigidity of single-agent, safety-only, traditional designs, rendering them ineffective for conducting contemporary early-phase clinical trials, such as those involving combinations and/or biological agents. Novel approaches are required to address these research questions, such as those posed in trials involving targeted therapies. We describe the implementation of a model-based design for identifying an optimal treatment combination, defined by low toxicity and high efficacy, in an early-phase trial evaluating a combination of two oral targeted inhibitors in relapsed/refractory mantle cell lymphoma. Operating characteristics demonstrate the ability of the method to effectively recommend optimal combinations in a high percentage of trials with reasonable sample sizes. The proposed design is a practical, early-phase, adaptive method for use with combined targeted therapies. This design can be applied more broadly to early-phase combination studies, as it was used in an ongoing study of a melanoma helper peptide vaccine plus novel adjuvant combinations. Clin Cancer Res; 23(23); 7158–64. ©2017 AACR.

Novel therapies for relapsed/refractory mantle cell lymphoma

Mantle cell lymphoma is an aggressive Non-Hodgkins lymphoma that is considered incurable with standard therapies. Most patients treated with frontline immunochemotherapy relapse within a few years and do not usually respond to salvage chemotherapy. Persistent activation of the B-cell receptor pathway is critical to the pathogenesis of mantle cell lymphoma. Inhibition of Brutons tyrosine kinase, an essential B-cell receptor pathway component with ibrutinib has shown clinical activity and has changed how MCL is treated in the relapsed/refractory setting. However, resistance to ibrutinib is common and response is limited. Novel agents targeting the B-cell receptor pathway along with therapies outside of the pathway will be reviewed in this article. Ongoing and future studies will better define how these agents should be utilized in the ever-changing treatment landscape of mantle cell lymphoma.

The phase 3 DUO trial: duvelisib versus ofatumumab in relapsed and refractory CLL/SLL

Duvelisib (also known as IPI-145) is an oral, dual inhibitor of phosphatidylinositol 3-kinase δ and γ (PI3K-δ,γ) being developed for treatment of hematologic malignancies. PI3K-δ,γ signaling can promote B-cell proliferation and survival in clonal B-cell malignancies, such as chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). In a phase 1 study, duvelisib showed clinically meaningful activity and acceptable safety in CLL/SLL patients. We report here the results of DUO, a global phase 3 randomized study of duvelisib vs ofatumumab monotherapy for patients with relapsed or refractory (RR) CLL/SLL. Patients were randomized 1:1 to oral duvelisib 25 mg twice daily (n = 160) or ofatumumab IV (n = 159). The study met the primary study end point by significantly improving progression-free survival per independent review committee assessment compared with ofatumumab for all patients (median, 13.3 months vs 9.9 months; hazard ratio [HR] = 0.52; P < .0001), including those with high-risk chromosome 17p13.1 deletions [del(17p)] and/or TP53 mutations (HR = 0.40; P = .0002). The overall response rate was significantly higher with duvelisib (74% vs 45%; P < .0001) regardless of del(17p) status. The most common adverse events were diarrhea, neutropenia, pyrexia, nausea, anemia, and cough on the duvelisib arm, and neutropenia and infusion reactions on the ofatumumab arm. The DUO trial data support duvelisib as a potentially effective treatment option for patients with RR CLL/SLL. This trial was registered at www.clinicaltrials.gov as #NCT02004522.

Orbital mantle cell lymphoma presenting as myasthenia gravis

ABSTRACT A 69-year-old man, previously treated with pyridostigmine for myasthenia gravis (manifesting as ptosis and diplopia) was evaluated for several concomitant bilateral anterior orbital masses. Imaging revealed 3 discrete, solid masses within and around the orbits. An incisional biopsy demonstrated atypical lymphocytes positive for CD20 and Cyclin-D1, consistent with mantle cell lymphoma. The patient received induction chemotherapy with a rituximab-based regimen. He experienced resolution of his diplopia and ptosis after one cycle of chemotherapy and achieved complete remission of the orbital masses and myasthenia symptoms after 6 cycles. Myasthenia gravis is most commonly associated with thymoma, but may also be observed with other malignancies. Recognition that orbital lymphoma may coexist with myasthenia gravis will help in expediting the diagnosis of future cases and in guiding treatment decisions.

Abstract B40: Synergistic cytotoxicity of ibrutinib and the BCL2 antagonist ABT-199 in mantle cell lymphoma and chronic lymphocytic leukemia: Molecular analysis reveals mechanisms of target interactions.

Bruton tyrosine kinase (BTK) is critical to both normal B-cell development and the pathogenesis of B-cell malignancies. Ibrutinib is a recently FDA-approved small molecule irreversible inhibitor of BTK, but not all patients respond and complete responses are infrequent with single agent ibrutinib. We hypothesize that additional agents used in combination could enhance the breadth, depth and duration of responses. We previously reported that the BCL2 inhibitor, ABT-199, and the proteasome inhibitor, carfilzomib, were highly synergistic with ibrutinib in MCL cell lines (Axelrod M et al, Leukemia 2014). We sought to confirm these findings in MCL and CLL patient samples and to determine the mechanisms of synergy. Peripheral blood buffy coat samples from patients with circulating tumor cells were exposed to ibrutinib, ABT-199, carfilzomib and the combinations of ibrutinib and ABT-199 and ibrutinib and carfilzomib at pharmacologically-achievable doses for 72 hours. Apoptosis was assessed using PARP cleavage by FACS analysis of CD3-, CD5+, CD19+ cells representing the neoplastic clones. The combination of Ibrutinib and ABT-199 displayed synergistic cytotoxicity (combo: 23%, ibrutinib: 3.8%, ABT-199: 3.0%). Ibrutinib plus carfilzomib also substantially induced apoptosis compared to each single agent alone (combo: 5.5%, Ibrutinib 3.8%, carfilzomib 1.7%) though to a less degree than the ABT-199 combination. The normal B-cell population (CD3-, CD5-, CD19+) in these samples was too small for analysis, thus normal T-cells (CD3+, CD5+, CD19-) from the same patients were used to identify the effects on normal lymphocytes. Minimal apoptosis was seen in normal T-cells with the single agents or the combinations. In a cohort of CLL cells from 9 patients, 5 displayed synergistic cytotoxicity and 4 did not, indicating substantial patient heterogeneity in response to the combination, presumably due to variations in genetic landscape. No increased apoptosis was seen in two tested peripheral blood lymphocyte (CD3-, CD5-, CD19+) populations from healthy donors. Gene expression profiling with Illumina Bead Chip array was used to evaluate the mechanisms of synergy with ABT-199 plus ibrutinib after 6 hours of drug exposure. The MCL cell line JVM2 was exposed to pharmacologically-achievable doses of ibrutinib, ABT-199 and combinations of each dose. Ibrutinib alone induced transcriptional change whereas ABT-199 did little to change gene expression. The combination induced both potentiative transcriptional changes (changes present in isolation and enhanced by the combination) and emergent transcriptional changes (changes only seen with the combination, unchanged by each single agent). Protein-protein interaction networks generated using the drug targets (BTK and BCL2) and emergent genes as input to STRING revealed activation of apoptosis via p53 and BIM as mechanisms of synergy. In conclusion, Ibrutinib and ABT-199 induce synergistic apoptosis in MCL cell lines and leukemic patient samples. The combination also induced apoptosis in some, but not all, CLL patient samples. No apoptosis was seen with either drug or the combination in normal T-cells from patients, suggesting little off-target effect. Emergent changes were seen when combining ABT-199 with ibrutinib in MCL cell lines. These changes suggest activation of p53 and BIM as potential mechanisms of synergy. A clinical trial with ABT-199 and ibrutinib is planned. Citation Format: Craig A. Portell, Mark J. Axelrod, Laura Kyle Brett, Vicki L. Gordon, Brian Capaldo, Jeffrey Xing, Stefan Bekiranov, Michael E. Williams, Michael J. Weber. Synergistic cytotoxicity of ibrutinib and the BCL2 antagonist ABT-199 in mantle cell lymphoma and chronic lymphocytic leukemia: Molecular analysis reveals mechanisms of target interactions. [abstract]. In: Proceedings of the AACR Special Conference on Hematologic Malignancies: Translating Discoveries to Novel Therapies; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(17 Suppl):Abstract nr B40.