Novel agents in the treatment of chronic lymphocytic leukemia: a review about the future

Biomaterial strategies for limiting the impact of secondary events following spinal cord injury

The nature of traumatic spinal cord injury (SCI) often involves limited recovery and long-term quality of life complications. The initial injury sets off a variety of secondary cascades, which result in an expanded lesion area. Ultimately, the native tissue fails to regenerate. As treatments are developed in the laboratory, the management of this secondary cascade is an important first step in achieving recovery of normal function. Current literature identifies four broad targets for intervention: inflammation, oxidative stress, disruption of the blood-spinal cord barrier, and formation of an inhibitory glial scar. Because of the complex and interconnected nature of these events, strategies that combine multiple therapies together show much promise. Specifically, approaches that rely on biomaterials to perform a variety of functions are generating intense research interest. In this review, we examine each target and discuss how biomaterials are currently used to address them. Overall, we show that there are an impressive amount of biomaterials and combinatorial treatments which show good promise for slowing secondary events and improving outcomes. If more emphasis is placed on growing our understanding of how materials can manage secondary events, treatments for SCI can be designed in an increasingly rational manner, ultimately improving their potential for translation to the clinic.

Efficacy of lenalidomide in relapsed/refractory chronic lymphocytic leukemia patient: a systematic review and meta-analysis

Therapeutic results of relapsed/refractory chronic lymphocytic leukemia (CLL) are very disappointing at present. Lenalidomide has been proved to be effective for relapsed/refractory CLL as a single agent or in combination with various chemo-immunotherapeutic regimens. However, current clinical experience in its usage is still limited. Because of existing considerable variability in different studies, a systematic review and meta-analysis was conducted to describe overall response rate (ORR) of lenalidomide in patients with relapsed/refractory CLL. Pooled estimate of cumulative prevalence of total ORR was 42.23 % (95 % confidence interval [CI], 32.49-52.61 %), while pooled ORR in regimen with lenalidomide plus anti-CD20 monoclonal antibody (mAbs) and lenalidomide mono-therapy were 60.01 % (95 % CI, 53.86-65.86 %) and 24.38 % (95 % CI, 16.15-35.06 %), respectively. There was no significant difference between L + R (lenalidomide plus rituximab) group and L + O (lenalidomide plus ofatumumab) group, with pooled ORR of 66.38 % (95 % CI, 57.96-73.87 %) and 57.40 % (95 % CI, 46.46-67.65 %), respectively. When co-administrated with anti-CD20 mAbs, dosage of lenalidomide was not the key factor of ORR in combination therapy. Pooled ORR of patient with high-risk cytogenetic in L + anti-CD20 mAbs group was 56.74 % (95 % CI, 45.53-67.30 %). In comparison with patients without high-risk cytogenetic receiving the same treatment regimen, no significant difference was observed, with relative risk (RR) of 0.87 (95 % CI 0.68-1.11). Our finding demonstrated that lenalidomide plus anti-CD20 mAbs could be an efficient therapy regimen for relapsed/refractory CLL patients, especially for those with high-risk cytogenetic factor.

PI3K pan-inhibition impairs more efficiently proliferation and survival of T-cell acute lymphoblastic leukemia cell lines when compared to isoform-selective PI3K inhibitors

Class I phosphatidylinositol 3-kinases (PI3Ks) are frequently activated in T-cell acute lymphoblastic leukemia (T-ALL), mainly due to the loss of PTEN function. Therefore, targeting PI3Ks is a promising innovative approach for T-ALL treatment, however at present no definitive evidence indicated which is the better therapeutic strategy between pan or selective isoform inhibition, as all the four catalytic subunits might participate in leukemogenesis. Here, we demonstrated that in both PTEN deleted and PTEN non deleted T-ALL cell lines, PI3K pan-inhibition exerted the highest cytotoxic effects when compared to both selective isoform inhibition or dual p110γ/δ inhibition. Intriguingly, the dual p110γ/δ inhibitor IPI-145 was effective in Loucy cells, which are representative of early T-precursor (ETP)-ALL, a T-ALL subtype associated with a poor outcome. PTEN gene deletion did not confer a peculiar reliance of T-ALL cells on PI3K activity for their proliferation/survival, as PTEN was inactivated in PTEN non deleted cells, due to posttranslational mechanisms. PI3K pan-inhibition suppressed Akt activation and induced caspase-independent apoptosis. We further demonstrated that in some T-ALL cell lines, autophagy could exert a protective role against PI3K inhibition. Our findings strongly support clinical application of class I PI3K pan-inhibitors in T-ALL treatment, with the possible exception of ETP-ALL cases.

Generation of Potent Anti-Vascular Endothelial Growth Factor Neutralizing Antibodies from Mouse Phage Display Library for Cancer Therapy

Vascular endothelial growth factor (VEGF) is an important stimulator for angiogenesis in solid tumors. Blocking VEGF activity is an effective therapeutic strategy to inhibit tumor growth and metastasis. Avastin, a humanized monoclonal antibody recognizes VEGF, has been approved by the US Food and Drug Administration. To generate potential VEGF-recognizing antibodies with better tumor regression ability than that of Avastin, we have designed a systematic antibody selection plan. From mice immunized with recombinant human VEGF, we generated three phage display libraries, scFv-M13KO7, Fab-M13KO7, and scFv-Hyperphage, in single-chain Fv (scFv) or Fab format, displayed using either M13KO7 helper phage or Hyperphage. Solid-phase and solution-phase selection strategies were then applied to each library, generating six panning combinations. A total of sixty-four antibodies recognizing VEGF were obtained. Based on the results of epitope mapping, binding affinity, and biological functions in tumor inhibition, eight antibodies were chosen to examine their abilities in tumor regression in a mouse xenograft model using human COLO 205 cancer cells. Three of them showed improvement in the inhibition of tumor growth (328%–347% tumor growth ratio (% of Day 0 tumor volume) on Day 21 vs. 435% with Avastin). This finding suggests a potential use of these three antibodies for VEGF-targeted therapy.

Potential Use of Flavopiridol in Treatment of Chronic Diseases

This chapter describes the potential use of flavopiridol, a CDK inhibitor with anti-inflammatory and anti-proliferative activities, in the treatment of various chronic diseases. Flavopiridol arrests cell cycle progression in the G1 or G2 phase by inhibiting the kinase activities of CDK1, CDK2, CDK4/6, and CDK7. Additionally, it binds tightly to CDK9, a component of the P-TEFb complex (CDK9/cyclin T), and interferes with RNA polymerase II activation and associated transcription. This in turn inhibits expression of several pro-survival and anti-apoptotic genes, and enhances cytotoxicity in transformed cells or differentiation in growth-arrested cells. Recent studies indicate that flavopiridol elicits anti-inflammatory activity via CDK9 and NFκB-dependent signaling. Overall, these effects of flavopiridol potentiate its ability to overcome aberrant cell cycle activation and/or inflammatory stimuli, which are mediators of various chronic diseases.

Combination of galectin inhibitor GCS-100 and BH3 mimetics eliminates both p53 wild type and p53 null AML cells

Galectin 3 (LGALS3) expression is prognostic for poor survival in acute myeloid leukemia (AML) patients. GCS-100 is a novel galectin inhibitor that may prove useful for AML therapy. In this study, we found that GCS-100 induced apoptosis in AML cells. The agent reduced MCL-1 expression suggesting that GCS-100 could be more effective when combined with a BH3 mimetic. Indeed, potent synergistic cytotoxicity was achieved when GCS-100 was combined with ABT-737 or ABT-199. Furthermore, the GCS-100/ABT-199 combination was effective against primary AML blast cells from patients with FLT3 ITD mutations, which is another prognostic factor for poor outcome in AML. This activity may involve wild-type p53 as shRNA knockdown of LGALS3 or galectin 1 (LGALS1) sensitized wild-type p53 OCI-AML3 cells to GCS-100/ABT-737-induced apoptosis to a much greater extent than p53 null THP-1 cells. Suppression of LGALS3 by shRNA inhibited MCL-1 expression in OCI-AML3 cells, but not THP-1 cells, suggesting the induced sensitivity to ABT-737 may involve a MCL-1 mediated mechanism. OCI-AML3 cells with LGALS1 shRNA were also sensitized to ABT-737. However, these cells exhibited increased MCL-1 expression, so MCL-1 reduction is apparently not required in this process. A role for p53 appears important as GCS-100 induces p53 expression and shRNA knockdown of p53 protected OCI-AML3 cells from the cytotoxic effects of the GCS-100/ABT-737 treatment combination. Our results suggest that galectins regulate a survival axis in AML cells, which may be targeted via combined inhibition with drugs such as GCS-100 and ABT-199.

New developments in the treatment of chronic lymphocytic leukemia: role of obinutuzumab

Obinutuzumab is a novel glycoengineered type II anti-CD20 monoclonal antibody with a higher affinity for CD20 epitope, enhanced antibody-dependent cellular cytotoxicity and direct cell death, leading to superior cytotoxicity compared with rituximab. The approval of obinutuzumab by US Food and Drug Administration was based on a pivotal, phase III, randomized trial of chlorambucil monotherapy (n=118), chlorambucil plus obinutuzumab (n=333), or chlorambucil plus rituximab (n=330) in previously untreated patients with CLL. Obinutuzumab was administered intravenously as 1,000 mg on days 1, 8, and 15 of cycle 1 and day 1 of subsequent cycles. Obinutuzumab plus chlorambucil was associated with an overall response rate of 78% and a median progression-free survival of 26.7 months. Overall, obinutuzumab was fairly well tolerated in this pivotal study. The incidence of grade 3 or higher adverse events was infusion-related reactions (20%), neutropenia (33%), thrombocytopenia (10%), and infections (7%). Obinutuzumab in combination with chlorambucil is a safe and effective new treatment option for previously untreated elderly patients with CLL. It should become the new standard of care for these patients with significant co-morbidities who are not candidates for fludarabine-based therapy. Obinutuzumab combination therapy with several agents that inhibit kinases involved in the B-cell receptor signaling pathway, as well as many other agents utilized in the frontline and relapsed/refractory setting, is currently under investigation. As the results from these studies become available, the role of obinutuzumab is expected to expand to other settings.

Idelalisib: A Novel PI3Kδ Inhibitor for Chronic Lymphocytic Leukemia

OBJECTIVE

To review and summarize data on idelalisib, which was approved by the Food and Drug Administration (FDA) in July 2014 for use in combination with rituximab for relapsed chronic lymphocytic leukemia (CLL).

DATA SOURCES

A literature search using PubMed was conducted from January 2011 through May 2015 using the terms idelalisib, GS-101, CAL-101, PI3Kδ, and CLL. Data were also obtained through the FDA briefing documents, American Society of Clinical Oncology, and American Society of Hematology abstracts.

STUDY SELECTION AND DATA EXTRACTION

The literature search was limited to human studies published in English. Priority was placed on trials of idelalisib in CLL.

DATA SYNTHESIS

Idelalisib is a potent, first-in-class selective inhibitor of phosphatidylinositol-3-kinaseδ (PI3Kδ) approved by the FDA in July 2014 for the treatment of relapsed CLL, in combination with rituximab, in patients for whom rituximab monotherapy would be considered appropriate due to other comorbidities. PI3Kδ is hyperactivated in B-cell malignancies and plays a vital role in the B-cell receptor pathway, a key oncogenic driver in various B-cell malignancies, including CLL. Several phase I/II studies have demonstrated clinical activity of idelalisib in CLL, particularly in the setting of relapsed/refractory disease, with overall response rate ranging from 70% to 82%. The FDA approval was based on a phase III, randomized trial of rituximab monotherapy (n = 110) or idelalisib in combination with rituximab (n = 110) in heavily, pre-treated patients (median of 3 prior therapies) with relapsed CLL. Idelalisib was administered as 150 mg orally twice daily. Idelalisib plus rituximab was associated with an overall response rate of 81% and overall survival of 91% at 12 months. The median progression-free survival was not reached in the idelalisib arm at the time of the first interim analysis. The incidence of grade 3 or higher adverse events in the idelalisib plus rituximab arm was as follows: neutropenia (34%), thrombocytopenia (10%), anemia (5%), elevation in transaminases (5%), and diarrhea (4%).

CONCLUSION

Idelalisib in combination with rituximab is a safe and effective new treatment option for patients with relapsed CLL, including those with poor prognostic factors. As the results from various ongoing studies become available, the role of idelalisib will likely continue to expand.