Clearance of systemic hematologic tumors by venetoclax (Abt-199) and navitoclax

Selective MCL-1 inhibitor ABBV-467 is efficacious in tumor models but is associated with cardiac troponin increases in patients

BACKGROUND

MCL-1 is a prosurvival B-cell lymphoma 2 family protein that plays a critical role in tumor maintenance and survival and can act as a resistance factor to multiple anticancer therapies. Herein, we describe the generation and characterization of the highly potent and selective MCL-1 inhibitor ABBV-467 and present findings from a first-in-human trial that included patients with relapsed/refractory multiple myeloma (NCT04178902).

METHODS

Binding of ABBV-467 to human MCL-1 was assessed in multiple cell lines. The ability of ABBV-467 to induce tumor growth inhibition was investigated in xenograft models of human multiple myeloma and acute myelogenous leukemia. The first-in-human study was a multicenter, open-label, dose-escalation study assessing safety, pharmacokinetics, and efficacy of ABBV-467 monotherapy.

RESULTS

Here we show that administration of ABBV-467 to MCL-1-dependent tumor cell lines triggers rapid and mechanism-based apoptosis. In vivo, intermittent dosing of ABBV-467 as monotherapy or in combination with venetoclax inhibits the growth of xenografts from human hematologic cancers. Results from a clinical trial evaluating ABBV-467 in patients with multiple myeloma based on these preclinical data indicate that treatment with ABBV-467 can result in disease control (seen in 1 patient), but may also cause increases in cardiac troponin levels in the plasma in some patients (seen in 4 of 8 patients), without other corresponding cardiac findings.

CONCLUSIONS

The selectivity of ABBV-467 suggests that treatment-induced troponin release is a consequence of MCL-1 inhibition and therefore may represent a class effect of MCL-1 inhibitors in human patients.

Anti-cancer peptides: their current trends in the development of peptide-based therapy and anti-tumor drugs

Human cancer remains a cause of high mortality throughout the world. The conventional methods and therapies currently employed for treatment are followed by moderate-to-severe side effects. They have not generated curative results due to the ineffectiveness of treatments. Besides, the associated high costs, technical requirements, and cytotoxicity further characterize their limitations. Due to relatively higher presidencies, bioactive peptides with anti-cancer attributes have recently become treatment choices within the therapeutic arsenal. The peptides act as potential anti-cancer agents explicitly targeting tumor cells while being less toxic to normal cells. The anti-cancer peptides are isolated from various natural sources, exhibit high selectivity and high penetration efficiency, and could be quickly restructured. The therapeutic benefits of compatible anti-cancer peptides have contributed to the significant expansion of cancer treatment; albeit, the mechanisms by which bioactive peptides inhibit the proliferation of tumor cells remain unclear. This review will provide a framework for assessing anti-cancer peptides' structural and functional aspects. It shall provide appropriate information on their mode of action to support and strengthen efforts to improve cancer prevention. The article will mention the therapeutic health benefits of anti-cancer peptides. Their importance in clinical studies is elaborated for reducing cancer incidences and developing sustainable treatment models.

Combined ibrutinib and venetoclax treatment vs single agents in the TCL1 mouse model for chronic lymphocytic leukemia

The covalent inhibitor of Bruton's tyrosine kinase ibrutinib and the specific Bcl-2 inhibitor venetoclax are both highly efficacious single agent drugs in the treatment of chronic lymphocytic leukemia (CLL). Based on their complementary modes of action, ibrutinib and venetoclax are hypothesized to act in synergistic fashion. Currently, it is unclear whether combined treatment is indeed superior to continuous single agent treatment, and what mechanisms could underlie resistance to combination treatment. In addition, effects of such treatment on the skewed T cell compartment characteristic for CLL are as yet unknown. In the murine Eµ-TCL1 adoptive transfer model, resembling aggressive CLL, we found that combined treatment resulted in deepest responses with longest duration due to a combination of decreased proliferation and increased induction of apoptosis. In addition, alterations in T cell subsets were most prominent upon combination treatment with increased naïve cells and reduced effector memory cells. Remarkably, effects of single agents but also combination treatment were eventually interrupted by relapse, and we found downregulation of BIM expression as a plausible cause of acquired drug resistance. Nevertheless, in this murine model, combination of venetoclax and ibrutinib has increased efficacy over single agents accompanied by a restoration of the T cell compartment.

Predicting ROR1/BCL2 combination targeted therapy of small cell carcinoma of the lung

Small cell lung cancer (SCLC) remains a deadly form of cancer, with a 5-year survival rate of less than 10 percent, necessitating novel therapies. Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is an oncofetal protein that is emerging as a therapeutic target and is co-expressed with BCL2 in multiple tumor types due to microRNA coregulation. We hypothesize that ROR1-targeted therapy is effective in small cell lung cancer and synergizes with therapeutic BCL2 inhibition. Tissue microarrays (TMAs) and formalin-fixed paraffin-embedded (FFPE) SCLC patient samples were utilized to determine the prevalence of ROR1 and BCL2 expression in SCLC. Eight SCLC-derived cell lines were used to determine the antitumor activity of a small molecule ROR1 inhibitor (KAN0441571C) alone and in combination with the BCL2 inhibitor venetoclax. The Chou-Talalay method was utilized to determine synergy with the drug combination. ROR1 and BCL2 protein expression was identified in 93% (52/56) and 86% (48/56) of SCLC patient samples, respectively. Similarly, ROR1 and BCL2 were shown by qRT-PCR to have elevated expression in 79% (22/28) and 100% (28/28) of SCLC patient samples, respectively. KAN0441571C displayed efficacy in 8 SCLC cell lines, with an IC50 of 500 nM or less. Synergy as defined by a combination index of <1 via the Chou-Talalay method between KAN0441571C and venetoclax was demonstrated in 8 SCLC cell lines. We have shown that ROR1 inhibition is synergistic with BCL2 inhibition in SCLC models and shows promise as a novel therapeutic target in SCLC.

Targeting cancer homing into the lymph node with a novel anti-CCR7 therapeutic antibody: the paradigm of CLL

Lymph node (LN) is a key tissue in the pathophysiology of mature blood cancers, especially for chronic lymphocytic leukemia (CLL). Within the multiple de-regulated pathways affecting CLL homeostasis, the CC-chemokine receptor 7 (CCR7) grants homing of CLL cells into the LN where protective environments foster tumor progression. To cover the lack of specific therapies targeting the CCR7-dependence of CLL to enter into the LN, and aiming to displace the disease from LN, we generated CAP-100, an antibody that specifically binds to hCCR7 and neutralizes its ligand-binding site and signaling. In various in vitro and in vivo preclinical models CAP-100 strongly inhibited CCR7-induced migration, extravasation, homing, and survival in CLL samples. Moreover, it triggered potent tumor cell killing, mediated by host immune mechanisms, and was effective in xenograft models of high-risk disease. Additionally, CAP-100 showed a favorable toxicity profile on relevant hematopoietic subsets. Our results validated CAP-100 as a novel therapeutic tool to prevent the access of CLL cells, and other neoplasia with nodal-dependence, into the LN niches, thus hitting a central hub in the pathogenesis of cancer. The first-in-human clinical trial (NCT04704323), which will evaluate this novel therapeutic approach in CLL patients, is pending.

Venetoclax – The Game-changer in Hematology

The introduction of small molecule inhibitors in many hematological malignancies made a landmark achievement in this field with a dramatic change in the survival outcome. Venetoclax is a B-cell lymphoma-2 inhibitor which has become the game-changer molecule in chronic lymphocytic leukemia and acute myeloid leukemia. This review is intended to summarize the mechanism of action, side effects, dosage, and different phases of clinical trials of this drug with review of literature.

Venetoclax: A Review in Relapsed/Refractory Chronic Lymphocytic Leukemia

Venetoclax (Venclyxto^®; Venclexta^®) is a first-in-class, oral, selective B cell lymphoma-2 (BCL-2) inhibitor. The drug is approved in numerous countries, including those of the EU and in the USA, for the treatment of adults with relapsed or refractory (RR) chronic lymphocytic leukemia (CLL); the specific indication(s) for venetoclax may vary between individual countries. Venetoclax monotherapy or combination therapy with rituximab was an effective treatment, provided durable responses, and had a manageable safety profile in pivotal clinical trials in adults with RR CLL, including in patients with adverse prognostic factors. In combination with 6 cycles of rituximab, venetoclax (fixed 24 months' treatment) was more effective than bendamustine plus rituximab (6 cycles) in prolonging progression-free survival (PFS) and inducing undetectable minimal residual disease (uMRD) in peripheral blood (PB) and bone marrow (BM), with these benefits sustained during 36 months' follow-up. Hence, with its novel mechanism of action and convenient oral once-daily regimen, venetoclax monotherapy or fixed 24-month combination therapy with rituximab represents an important option for treating RR CLL, including in patients with del(17p) or TP53 mutation and those failing a B cell receptor (BCR) inhibitor and/or chemotherapy.

Effects of Buprenorphine in a Preclinical Orthotopic Tumor Model of Ovarian Carcinoma in Female CB17 SCID Mice

In the development of cancer therapeutics, no suitable replacements for the use of animals that are capable of modeling such complex disease processes are currently available. In orthotopic models, surgery is often required to access the target organ for tumor cell inoculation. Historically analgesics have been withheld in such models in light of potential effects on tumor development. The current study evaluated the effect of the opioid buprenorphine on tumor growth of a human ovarian cancer cell line (OVCAR5 OT luc2 mCherry). Female CB17 SCID mice (n = 150) underwent surgery for orthotopic inoculation and were assigned to 1 of 3 treatment groups: vehicle control, 1 dose of buprenorphine, or 2 doses of buprenorphine administered perioperatively. Bioluminescence imaging revealed no significant difference on tumor engraftment rate or growth between control and analgesia-treated groups. These data demonstrate that acute, perioperative analgesia with buprenorphine did not alter tumor growth. Although further research is needed to evaluate potential effects of buprenorphine in other cell lines and mouse strains, the justification for withholding analgesia and the potential influence of pain and stress due to insufficient analgesia in these models should be considered thoroughly.

Introduction of novel agents in the treatment of primary CNS lymphoma

Novel insights into the pathophysiology of primary central nervous system lymphoma (PCNSL) have identified the B-cell receptor and Toll-like receptor pathway as well as immune evasion and suppressed tumor immune microenvironment as a key mechanism in the pathogenesis of PCNSL. Small molecules and novel agents targeting these aberrant pathways have been introduced into clinical trials targeting the recurrent or refractory PCNSL patient population. Agents like the Bruton tyrosine kinase (BTK) inhibitor ibrutinib or immunomodulatory drugs (IMiDs) like pomalidomide and lenalidomide have shown promising high response rates in the salvage setting. Here, we give an overview about the recent, exciting developments in PCNSL and summarize the results of clinical trials using novel agents in the recurrent and refractory salvage setting, which include immune checkpoint inhibitors, IMiDs, as well as BTK, phosphatidylinositol-3 kinase, and mammalian target of rapamycin inhibitors.

New Approaches to the Management of Adult Acute Lymphoblastic Leukemia

Traditional treatment regimens for adult acute lymphoblastic leukemia, including allogeneic hematopoietic cell transplantation, result in an overall survival of approximately 40%, a figure hardly comparable with the extraordinary 80% to 90% cure rate currently reported in children. When translated to the adult setting, modern pediatric-type regimens improve the survival to approximately 60% in young adults. The addition of tyrosine kinase inhibitors for patients with Philadelphia chromosome-positive disease and the measurement of minimal residual disease to guide risk stratification and postremission approaches has led to additional improvements in outcomes. Relapsed disease and treatment toxicity-sparing no patient but representing a major concern especially in the elderly-are the most critical current issues awaiting further therapeutic advancement. Recently, there has been considerable progress in understanding the disease biology, specifically the Philadelphia-like signature, as well as other high-risk subgroups. In addition, there are several new agents that will undoubtedly contribute to additional improvement in the current outcomes. The most promising agents are monoclonal antibodies, immunomodulators, and chimeric antigen receptor T cells, and, to a lesser extent, several new drugs targeting key molecular pathways involved in leukemic cell growth and proliferation. This review examines the evidence supporting the increasing role of the new therapeutic tools and treatment options in different disease subgroups, including frontline and relapsed or refractory disease. It is now possible to define the best individual approach on the basis of the emerging concepts of precision medicine.

Accelerating drug development in pediatric cancer: a novel Phase I study design of venetoclax in relapsed/refractory malignancies

Venetoclax is a highly selective, potent BCL-2 inhibitor that is approved for some patients previously treated for chronic lymphocytic leukemia, and has shown promising activity in adult studies across several hematologic malignancies. Preclinical studies have demonstrated venetoclax activity in pediatric patient-derived xenograft models and cell lines; however, clinical studies in pediatric patients have yet to be conducted. The prognosis is poor for children with most relapsed/refractory malignancies, and limited treatment options result in unmet clinical need. Herein, we describe the rationale and design of the first study of venetoclax in pediatric patients with relapsed/refractory malignancies: a Phase I trial investigating the safety and pharmacokinetics of venetoclax monotherapy followed by the addition of chemotherapy (Trial registration: EudraCT 2017-000439-14; NCT03236857).

Found in Translation: How Preclinical Research Is Guiding the Clinical Development of the BCL2-Selective Inhibitor Venetoclax

Since the discovery of apoptosis as a form of programmed cell death, targeting the apoptosis pathway to induce cancer cell death has been a high-priority goal for cancer therapy. After decades of effort, drug-discovery scientists have succeeded in generating small-molecule inhibitors of antiapoptotic BCL2 family proteins. Innovative medicinal chemistry and structure-based drug design, coupled with a strong fundamental understanding of BCL2 biology, were essential to the development of BH3 mimetics such as the BCL2-selective inhibitor venetoclax. We review a number of preclinical studies that have deepened our understanding of BCL2 biology and facilitated the clinical development of venetoclax.Significance: Basic research into the pathways governing programmed cell death have paved the way for the discovery of apoptosis-inducing agents such as venetoclax, a BCL2-selective inhibitor that was recently approved by the FDA and the European Medicines Agency. Preclinical studies aimed at identifying BCL2-dependent tumor types have translated well into the clinic thus far and will likely continue to inform the clinical development of venetoclax and other BCL2 family inhibitors. Cancer Discov; 7(12); 1376-93. ©2017 AACR.

Therapeutics targeting Bcl-2 in hematological malignancies

Members of the B-cell lymphoma 2 (BCL-2) gene family are attractive targets for cancer therapy as they play a key role in promoting cell survival, a long-since established hallmark of cancer. Clinical utility for selective inhibition of specific anti-apoptotic Bcl-2 family proteins has recently been realized with the Food and Drug Administration (FDA) approval of venetoclax (formerly ABT-199/GDC-0199) in relapsed chronic lymphocytic leukemia (CLL) with 17p deletion. Despite the impressive monotherapy activity in CLL, such responses have rarely been observed in other B-cell malignancies, and preclinical data suggest that combination therapies will be needed in other indications. Additional selective antagonists of Bcl-2 family members, including Bcl-X_L and Mcl-1, are in various stages of preclinical and clinical development and hold the promise of extending clinical utility beyond CLL and overcoming resistance to venetoclax. In addition to direct targeting of Bcl-2 family proteins with BH3 mimetics, combination therapies that aim at down-regulating expression of anti-apoptotic BCL-2 family members or restoring expression of pro-apoptotic BH3 family proteins may provide a means to deepen responses to venetoclax and extend the utility to additional indications. Here, we review recent progress in direct and selective targeting of Bcl-2 family proteins for cancer therapy and the search for rationale combinations.

Bioluminescence Imaging Enhances Analysis of Drug Responses in a Patient-Derived Xenograft Model of Pediatric ALL

Purpose: Robust preclinical models of pediatric acute lymphoblastic leukemia (ALL) are essential in prioritizing promising therapies for clinical assessment in high-risk patients. Patient-derived xenograft (PDX) models of ALL provide a clinically relevant platform for assessing novel drugs, with efficacy generally assessed by enumerating circulating human lymphoblasts in mouse peripheral blood (PB) as an indicator of disease burden. While allowing indirect measurement of disease burden in real time, this technique cannot assess treatment effects on internal reservoirs of disease. We explore benefits of bioluminescence imaging (BLI) to evaluate drug responses in ALL PDXs, compared with PB monitoring. BLI-based thresholds of drug response are also explored.Experimental Design: ALL PDXs were lentivirally transduced to stably express luciferase and green fluorescent protein. In vivo PDX responses to an induction-type regimen of vincristine, dexamethasone, and L-asparaginase were assessed by BLI and PB. Residual disease at day 28 after treatment initiation was assessed by flow cytometric analysis of major organs. BLI and PB were subsequently used to evaluate efficacy of the Bcl-2 inhibitor venetoclax.Results: BLI considerably accelerated and enhanced detection of leukemia burden compared with PB and identified sites of residual disease during treatment in a quantitative manner, highlighting limitations in current PB-based scoring criteria. Using BLI alongside enumeration of human lymphoblasts in PB and bone marrow, we were able to redefine response criteria analogous to the clinical setting.Conclusions: BLI substantially improves the stringency of preclinical drug testing in pediatric ALL PDXs, which will likely be important in prioritizing effective agents for clinical assessment. Clin Cancer Res; 23(14); 3744-55. ©2017 AACR.

Nodal marginal zone lymphoma: Clinical features, diagnosis, management and treatment

Nodular marginal zone lymphoma (NMZL) is a small B-cell lymphoma involving only lymph nodes and is the least common form of MZL constituting about 10% of cases. Patients usually present with advanced disease which must be distinguished from extranodal MZL with lymph node spread. NMZL shares cytological and immunophenotypic features with MALT and splenic MZL, but has a less favorable prognosis than these two categories. It occurs mostly in adults and pediatric cases are rare. Different therapeutic approaches have been used in NMZL, but because of the small patient numbers involved, more definitive treatment is still anticipated. Recent studies suggest that it probably represents a separate entity within the broader indolent lymphoma category. In NMZL there is an emerging need to utilize novel agents, already available for indolent lymphomas. Prospective studies are required to evaluate their therapeutic efficacy for NMZL in the future.

The potential of venetoclax (ABT-199) in chronic lymphocytic leukemia

Venetoclax (VEN, ABT-199/GDC-0199) is an orally bioavailable BH3-mimetic that specifically inhibits the anti-apoptotic B-cell lymphoma/leukemia 2 (BCL2) protein. Although BCL2 overexpression is not genetically driven in chronic lymphocytic leukemia (CLL), it is nearly universal and represents a highly important and prevalent mechanism of apoptosis evasion, making it an attractive therapeutic target. This review summarizes the role of BCL2 in CLL pathogenesis, the development path targeting its inhibition prior to VEN, and the preclinical and clinical data regarding the effectiveness and safety of VEN. We further strive to contextualize VEN in the current CLL treatment landscape and discuss potential mechanisms of resistance.

Clinical Predictors of Venetoclax Pharmacokinetics in Chronic Lymphocytic Leukemia and Non-Hodgkin's Lymphoma Patients: a Pooled Population Pharmacokinetic Analysis

Venetoclax (ABT-199/GDC-0199) is a selective, potent, first-in-class BCL-2 inhibitor that restores apoptosis in cancer cells and has demonstrated clinical efficacy in a variety of hematological malignancies. The objective of this analysis was to characterize the population pharmacokinetics of venetoclax and identify demographic, pathophysiologic, and treatment factors that influence its pharmacokinetics. Plasma concentration samples from 505 subjects enrolled in 8 clinical studies were analyzed using non-linear mixed-effects modeling. Venetoclax plasma concentrations were best described by a two-compartment PK model with first-order absorption and elimination. The terminal half-life in cancer subjects was estimated to be approximately 26 h. Moderate and strong CYP3A inhibitors decreased venetoclax apparent clearance by 19% and 84%, respectively, while weak CYP3A inhibitors and inducers did not affect clearance. Additionally, concomitant rituximab administration was estimated to increase venetoclax apparent clearance by 21%. Gastric acid-reducing agent co-administration had no impact on the rate or extent of venetoclax absorption. Females had 32% lower central volume of distribution when compared to males. Food increased the bioavailability by 2.99- to 4.25-fold when compared to the fasting state. Mild and moderate renal and hepatic impairment, body weight, age, race, weak CYP3A inhibitors and inducers as well as OATP1B1 transporter phenotype and P-gp, BCRP, and OATP1B1/OATP1B3 modulators had no impact on venetoclax pharmacokinetics. Venetoclax showed minimal accumulation with accumulation ratio of 1.30-1.44. In conclusion, the concomitant administration of moderate and strong CYP3A inhibitors and rituximab as well as food were the main factors impacting venetoclax pharmacokinetics, while patient characteristics had only minimal impact.