Application of a sequential multiple assignment randomized trial (SMART) design in older patients with chronic lymphocytic leukemia.

BACKGROUND: Ibrutinib therapy is safe and effective in patients with chronic lymphocytic leukemia (CLL). Currently, ibrutinib is administered continuously until disease progression. Combination regimens with ibrutinib are being developed to deepen response which could allow for ibrutinib maintenance (IM) discontinuation. Among untreated older patients with CLL, clinical investigators had the following questions: (i) does ibrutinib + venetoclax + obinutuzumab (IVO) with IM have superior progression-free survival (PFS) compared with ibrutinib + obinutuzumab (IO) with IM, and (ii) does the treatment strategy of IVO + IM for patients without minimal residual disease complete response (MRD- CR) or IVO + IM discontinuation for patients with MRD- CR have superior PFS compared with IO + IM. DESIGN: Conventional designs randomize patients to IO with IM or IVO with IM to address the first objective, or randomize patients to each treatment strategy to address the second objective. A sequential multiple assignment randomized trial (SMART) design and analysis is proposed to address both objectives. RESULTS: A SMART design strategy is appropriate when comparing adaptive interventions, which are defined by an individual's sequence of treatment decisions and guided by intermediate outcomes, such as response to therapy. A review of common applications of SMART design strategies is provided. Specific to the SMART design previously considered for Alliance study A041702, the general structure of the SMART is presented, an approach to sample size and power calculations when comparing adaptive interventions embedded in the SMART with a time-to-event end point is fully described, and analyses plans are outlined. CONCLUSION: SMART design strategies can be used in cancer clinical trials with adaptive interventions to identify optimal treatment strategies. Further, standard software exists to provide sample size, power calculations, and data analysis for a SMART design.

Extended follow-up and impact of high-risk prognostic factors from the phase 3 RESONATE study in patients with previously treated CLL/SLL.

In the phase 3 RESONATE study, ibrutinib demonstrated superior progression-free survival (PFS), overall survival (OS) and overall response rate (ORR) compared with ofatumumab in relapsed/refractory CLL patients with high-risk prognostic factors. We report updated results from RESONATE in these traditionally chemotherapy resistant high-risk genomic subgroups at a median follow-up of 19 months. Mutations were detected by Foundation One Heme Panel. Baseline mutations in the ibrutinib arm included TP53 (51%), SF3B1 (31%), NOTCH1 (28%), ATM (19%) and BIRC3 (14%). Median PFS was not reached, with 74% of patients randomized to ibrutinib alive and progression-free at 24 months. The improved efficacy of ibrutinib vs ofatumumab continues in all prognostic subgroups including del17p and del11q. No significant difference within the ibrutinib arm was observed for PFS across most genomic subtypes, although a subset carrying both TP53 mutation and del17p had reduced PFS compared with patients with neither abnormality. Reduced PFS or OS was not evident in patients with only del17p. PFS was significantly better for ibrutinib-treated patients in second-line vs later lines of therapy. The robust clinical activity of ibrutinib continues to show ongoing efficacy and acceptable safety consistent with prior reports, independent of various known high-risk mutations.

The mutational oncoprint of recurrent cytogenetic abnormalities in adult patients with de novo acute myeloid leukemia.

Recurrent chromosomal abnormalities and gene mutations detected at the time of diagnosis of acute myeloid leukemia (AML) are associated with particular disease features, treatment response and survival of AML patients, and are used to denote specific disease entities in the World Health Organization classification of myeloid neoplasms and acute leukemia. However, large studies that integrate cytogenetic and comprehensive mutational information are scarce. We created a comprehensive oncoprint of mutations associated with recurrent cytogenetic findings by combining the information on mutational patterns of 80 cancer- and leukemia-associated genes with cytogenetic findings in 1603 adult patients with de novo AML. We show unique differences in the mutational profiles among major cytogenetic subsets, identify novel associations between recurrent cytogenetic abnormalities and both specific gene mutations and gene functional groups, and reveal differences in cytogenetic and mutational features between patients younger than 60 years and those aged 60 years or older. The identified associations between cytogenetic and molecular genetic data may help guide mutation testing in AML, and result in more focused application of targeted therapy in patients with de novo AML.

Leukemia-cell proliferation and disease progression in patients with early stage chronic lymphocytic leukemia.

The clinical course of patients with recently diagnosed early stage chronic lymphocytic leukemia (CLL) is highly variable. We examined the relationship between CLL-cell birth rate and treatment-free survival (TFS) in 97 patients with recently diagnosed, Rai stage 0-II CLL in a blinded, prospective study, using in vivo 2H2O labeling. Birth rates ranged from 0.07 to 1.31% new cells per day. With median follow-up of 4.0 years, 33 subjects (34%) required treatment by NCI criteria. High-birth rate was observed in 44% of subjects and was significantly associated with shorter TFS, unmutated IGHV status and expression of ZAP70 and of CD38. In multivariable modeling considering age, gender, Rai stage, expression of ZAP70 or CD38, IGHV mutation status and FISH cytogenetics, only CLL-cell birth rate and IGHV mutation status met criteria for inclusion. Hazard ratios were 3.51 (P=0.002) for high-birth rate and 4.93 (P<0.001) for unmutated IGHV. The association between elevated birth rate and shorter TFS was observed in subjects with either mutated or unmutated IGHVs, and the use of both markers was a better predictor of TFS than either parameter alone. Thus, an increased CLL birth rate in early stage disease is a strong predictor of disease progression and earlier treatment.

Mutations in the CCND1 and CCND2 genes are frequent events in adult patients with t(8;21)(q22;q22) acute myeloid leukemia.

Core-binding factor acute myeloid leukemia (CBF-AML) is defined by the presence of either t(8;21)(q22;q22)/RUNX1-RUNX1T1 or inv(16)(p13.1q22)/t(16;16)(p13.1;q22)/CBFB-MYH11. The resulting fusion genes require a 'second hit' to initiate leukemogenesis. Mutation assessment of 177 adults with CBF-AML, including 68 with t(8;21) and 109 with inv(16)/t(16;16), identified not only mutations well known in CBF-AML but also mutations in the CCND1 and CCND2 genes, which represent novel frequent molecular alterations in AML with t(8;21). Altogether, CCND1 (n=2) and CCND2 (n=8) mutations were detected in 10 (15%) patients with t(8;21) in our cohort. A single CCND2 mutation was also found in 1 (0.9%) patient with inv(16). In contrast, CCND1 and CCND2 mutations were detected in only 11 (0.77%) of 1426 non-CBF-AML patients. All CCND2 mutations cluster around the highly conserved amino-acid residue threonine 280 (Thr280). We show that Thr280Ala-mutated CCND2 leads to increased phosphorylation of the retinoblastoma protein, thereby causing significant cell cycle changes and increased proliferation of AML cell lines. The identification of CCND1 and CCND2 mutations as frequent mutational events in t(8;21) AML may provide further justification for cell cycle-directed therapy in this disease.

Non-immunosuppressive FTY720-derivative OSU-2S mediates reactive oxygen species-mediated cytotoxicity in canine B-cell lymphoma.

OSU-2S is a FTY720 (Fingolimod) derivative that lacks immunosuppressive properties but exhibits strong anti-tumour activity in several haematological and solid tumour models. We have recently shown OSU-2S to mediate potent cytotoxicity in human mantle cell lymphoma cell lines and primary cells. We report here the pre-clinical activity of OSU-2S in spontaneous B-cell lymphoma of dogs which shares many characteristics of human lymphoma. OSU-2S mediated apoptosis in canine B-cell lines and primary B-cell lymphoma cells obtained from spontaneous lymphoma bearing dogs. OSU-2S induced reactive oxygen species (ROS) in canine lymphoma cells and inhibition of ROS partially rescued OSU-2S-mediated cell death. These studies provide a rational basis for the use of spontaneous lymphoma in pet dogs as a preclinical large animal model for the development of OSU-2S as small molecule for treating people and dogs with lymphoma.

Next-generation XPO1 inhibitor shows improved efficacy and in vivo tolerability in hematological malignancies.

The nuclear export receptor, Exportin 1 (XPO1), mediates transport of growth-regulatory proteins, including tumor suppressors, and is overactive in many cancers, including chronic lymphocytic leukemia (CLL), acute myeloid leukemia (AML) and aggressive lymphomas. Oral selective inhibitor of nuclear export (SINE) compounds that block XPO1 function were recently identified and hold promise as a new therapeutic paradigm in many neoplasms. One of these compounds, KPT-330 (selinexor), has made progress in Phase I/II clinical trials, but systemic toxicities limit its administration to twice-per-week and requiring supportive care. We designed a new generation SINE compound, KPT-8602, with a similar mechanism of XPO1 inhibition and potency but considerably improved tolerability. Efficacy of KPT-8602 was evaluated in preclinical animal models of hematological malignancies, including CLL and AML. KPT-8602 shows similar in vitro potency compared with KPT-330 but lower central nervous system penetration, which resulted in enhanced tolerability, even when dosed daily, and improved survival in CLL and AML murine models compared with KPT-330. KPT-8602 is a promising compound for further development in hematological malignancies and other cancers in which upregulation of XPO1 is seen. The wider therapeutic window of KPT-8602 may also allow increased on-target efficacy leading to even more efficacious combinations with other targeted anticancer therapies.

Incidence and description of autoimmune cytopenias during treatment with ibrutinib for chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is frequently complicated by secondary autoimmune cytopenias (AICs). Ibrutinib is an irreversible inhibitor of Bruton's tyrosine kinase approved for the treatment of relapsed CLL and CLL with del(17p). The effect of ibrutinib treatment on the incidence of AIC is currently unknown. We reviewed medical records of 301 patients treated with ibrutinib, as participants in therapeutic clinical trials at The Ohio State University Comprehensive Cancer Center between July 2010 and July 2014. Subjects were reviewed with respect to past history of AIC, and treatment-emergent AIC cases were identified. Before starting ibrutinib treatment, 26% of patients had experienced AIC. Information was available for a total of 468 patient-years of ibrutinib exposure, during which there were six cases of treatment-emergent AIC. This corresponds to an estimated incidence rate of 13 episodes for every 1000 patient-years of ibrutinib treatment. We further identified 22 patients receiving therapy for AIC at the time ibrutinib was started. Of these 22 patients, 19 were able to discontinue AIC therapy. We found that ibrutinib treatment is associated with a low rate of treatment-emergent AIC. Patients with an existing AIC have been successfully treated with ibrutinib and subsequently discontinued AIC therapy.

Dinaciclib is a novel cyclin-dependent kinase inhibitor with significant clinical activity in relapsed and refractory chronic lymphocytic leukemia.

Dinaciclib (SCH727965) is a selective CDKi chosen for clinical development based upon a favorable therapeutic index in cancer xenograft models. We performed a phase I dose escalation study of dinaciclib in relapsed and refractory chronic lymphocytic leukemia (CLL) patients with intact organ function and WBC<200 × 10(9) /l. Five separate dose levels (5 mg/m(2), 7 mg/m(2), 10 mg/m(2), 14 mg/m(2) and 17 mg/m(2)) were explored dosing on a weekly schedule × 3 with 1 week off (4-week cycles) using a standard 3+3 design with expansion cohorts to optimize safety. Fifty-two patients were enrolled with relapsed and refractory CLL. Escalation through cohorts occurred with two dose-limiting toxicity (DLTs) at the 17 mg/m(2) dose (tumor lysis syndrome (TLS) and pneumonia). The phase II expansion occurred at 14 mg/m(2) with 16 patients receiving this dose with one DLT (TLS). Additional stepped up dosing to the maximum tolerated dose was examined in 19 patients at this dose. Adverse events included cytopenias, transient laboratory abnormalities and TLS. Responses occurred in 28 (54%) of patients independent of del(17)(p13.1) with a median progression-free survival of 481 days. Dinaciclib is clinically active in relapsed CLL including those patients with high risk del(17)(p13.1) disease and warrants future study.

Tumor antigen ROR1 targeted drug delivery mediated selective leukemic but not normal B-cell cytotoxicity in chronic lymphocytic leukemia.

Selective cytotoxicity to cancer cells without compromising their normal counterparts pose a huge challenge for traditional drug design. Here we developed a tumor antigen-targeted delivery of immunonanoparticle carrying a novel non-immunosuppressive FTY720 derivative OSU-2S with potent cytotoxicity against leukemic B cells. OSU-2S induces activation of protein phosphatase 2A (PP2A), phosphorylation and nuclear translocation of SHP1(S591) and deregulation of multiple cellular processes in chronic lymphocytic leukemia (CLL) resulting in potent cytotoxicity. To preclude OSU-2S-mediated effects on these ubiquitous phosphatases in unintended cells and avoid potential adverse effects, we developed an OSU-2S-targeted delivery of immunonanoparticles (2A2-OSU-2S-ILP), that mediated selective cytotoxicity of CLL but not normal B cells through targeting receptor tyrosine kinase ROR1 expressed in leukemic but not normal B cells. Developing a novel spontaneous CLL mouse model expressing human ROR1 (hROR1) in all leukemic B cells, we demonstrate the therapeutic benefit of enhanced survival with 2A2-OSU-2S-ILP in vivo. The newly developed non-immunosuppressive OSU-2S, its delivery using human CLL directed immunonanoparticles and the novel transgenic (Tg) mouse model of CLL that expresses hROR1 exclusively in leukemic B cell surface are highly innovative and can be applied to CLL and other ROR1+ malignancies including mantle cell lymphoma and acute lymphoblastic leukemia.

The CD37-targeted antibody-drug conjugate IMGN529 is highly active against human CLL and in a novel CD37 transgenic murine leukemia model.

Therapeutic regimens for chronic lymphocytic leukemia (CLL) have increasingly utilized monoclonal antibodies since the chimeric anti-CD20 antibody rituximab was introduced. Despite improved clinical outcomes, current CLL therapies are not curative. Therefore, antibodies with greater efficacy and novel targets are desirable. One promising target is CD37, a tetraspanin protein highly expressed on malignant B-cells in CLL and non-Hodgkin lymphoma. Although several novel CD37-directed therapeutics are emerging, detailed preclinical evaluation of these agents is limited by lack of appropriate animal models with spontaneous leukemia expressing the human CD37 (hCD37) target. To address this, we generated a murine CLL model that develops transplantable hCD37+ leukemia. Subsequently, we engrafted healthy mice with this leukemia to evaluate IMGN529, a novel hCD37-targeting antibody-drug conjugate. IMGN529 rapidly eliminated peripheral blood leukemia and improved overall survival. In contrast, the antibody component of IMGN529 could not alter disease course despite exhibiting substantial in vitro cytotoxicity. Furthermore, IMGN529 is directly cytotoxic to human CLL in vitro, depletes B-cells in patient whole blood and promotes killing by macrophages and natural killer cells. Our results demonstrate the utility of a novel mouse model for evaluating anti-human CD37 therapeutics and highlight the potential of IMGN529 for treatment of CLL and other CD37-positive B-cell malignancies.