Idelalisib, an inhibitor of phosphatidylinositol 3-kinase p110δ, for relapsed/refractory chronic lymphocytic leukemia. Blood. 2014;123:3390-3397. [PMID: 24615777 DOI: 10.1182/blood-2013-11-535047]

BCL-2 and BTK inhibitors for chronic lymphocytic leukemia: current treatments and overcoming resistance

INTRODUCTION

In the last decade, BTK inhibitors and the BCL-2 inhibitor venetoclax have replaced immunochemotherapy in the treatment of CLL.

AREAS COVERED

This review describes the use of BTK inhibitors and BCL2 inhibitors in the treatment of naive and relapsed or refractory CLL, with particular attention to the mechanisms of resistance. It also addresses the management of double-refractory patients, and the discovery of novel drugs. The corpus of papers was obtained by a search of the PubMed and Google Scholar databases for articles in English.

EXPERT OPINION

Covalent BTK inhibitors and venetoclax are commonly recommended for previously-untreated and relapsed/refractory CLL. However, resistance to both drug classes can develop over time. As such, double-refractory patients are difficult to manage and novel approaches are urgently needed.

Potential impact of NOTCH1 activation on venetoclax sensitivity in chronic lymphocytic Leukaemia: In vitro insights and clinical implications

Despite significant progress in treating chronic lymphocytic leukaemia (CLL), resistance to therapy remains challenging. NOTCH1 activation, common in CLL, confers adverse prognosis. This study explores the impact of NOTCH1 signalling on venetoclax sensitivity in vitro. Although NOTCH1 activation minimally impaired the susceptibility of CLL cells to venetoclax, ex vivo cell competition studies reveal that cells with constitutive NOTCH1 activation outgrew their wild-type counterparts in the presence of ongoing venetoclax exposure. Our findings suggest that while NOTCH1 activation is insufficient to confer venetoclax refractoriness, there is enhanced potential for cells with NOTCH1 activation to escape and thus become fully resistant to venetoclax.

The PI3K signaling pathway; from normal lymphopoiesis to lymphoid malignancies

INTRODUCTION

As a vital mechanism of survival, lymphopoiesis requires the collaboration of different signaling molecules to orchestrate each step of cell development and maturation. The PI3K pathway is considerably involved in the maturation of lymphatic cells and therefore, its dysregulation can immensely affect human well-being and cause some of the most prevalent malignancies. As a result, studies that investigate this pathway could pave the way for a better understanding of the lymphopoiesis mechanisms, the undesired changes that lead to cancer progression, and how to design drugs to solve this issue.

AREAS COVERED

The present review addresses the aforementioned aspects of the PI3K pathway and helps pave the way for future therapeutic approaches. In order to access the articles, databases such as Medicine Medline/PubMed, Scopus, Google Scholar, and Science Direct were utilized. The search formula was established by identifying main keywords including PI3K/Akt/mTOR pathway, Lymphopoiesis, Lymphoid malignancies, and inhibitors.

EXPERT OPINION

The PI3K pathway is crucial for lymphocyte development and differentiation, making it a potential target for therapeutic intervention in lymphoid cancers. Studies are focused on developing PI3K inhibitors to impede the progression of hematologic malignancies, highlighting the pathway's significance in lymphoma and lymphoid leukemia.

Dose optimization for cancer treatments with considerations for late-onset toxicities

Given that novel anticancer therapies have different toxicity profiles and mechanisms of action, it is important to reconsider the current approaches for dose selection. In an effort to move away from considering the maximum tolerated dose as the optimal dose, the Food and Drug Administration Project Optimus points to the need of incorporating long-term toxicity evaluation, given that many of these novel agents lead to late-onset or cumulative toxicities and there are no guidelines on how to handle them. Numerous methods have been proposed to handle late-onset toxicities in dose-finding clinical trials. A summary and comparison of these methods are provided. Moreover, using PI3K inhibitors as a case study, we show how late-onset toxicity can be integrated into the dose-optimization strategy using current available approaches. We illustrate a re-design of this trial to compare the approach to those that only consider early toxicity outcomes and disregard late-onset toxicities. We also provide proposals going forward for dose optimization in early development of novel anticancer agents with considerations for late-onset toxicities.

Targeting the NTSR2/TrkB oncogenic pathway in chronic lymphocytic leukemia

Current therapies that target the B-cell receptor pathway or the inhibition of anti-apoptotic proteins do not prevent the progressive forms of chronic lymphocytic leukemia (CLL), have low long-term efficacy and are subject to therapeutic resistance. Deciphering the mechanisms of leukemic cell survival and searching for new specific targets therefore remain major challenges to improve the management of this disease. It was evidenced that NTSR2 (neurotensin receptor 2), through the recruitment of TRKB (tropomyosin related kinase B), induces survival pathways in leukemic B cells. We have investigated the therapeutic potential of this protein complex as a new target. The binding domain of NTSR2 and TRKB was identified and a peptide targeting the latter was designed. The peptide binds TRKB and efficiently decreases the interaction of the two proteins. It is also effectively internalized by CLL-B cells in which it notably affects Src family kinase signaling and anti-apoptotic proteins levels. It demonstrated a cytotoxic effect both in vitro on the MEC-1 cell line and ex vivo on a cohort of 30 CLL patients. Altogether, these results underline the therapeutic potential of the NTSR2/TRKB protein complex as a target in CLL and open new perspectives for the development of targeted therapies.

B cell receptor signaling and associated pathways in the pathogenesis of chronic lymphocytic leukemia

B cell antigen receptor (BCR) signaling is a key driver of growth and survival in both normal and malignant B cells. Several lines of evidence support an important pathogenic role of the BCR in chronic lymphocytic leukemia (CLL). The significant improvement of CLL patients' survival with the use of various BCR pathway targeting inhibitors, supports a crucial involvement of BCR signaling in the pathogenesis of CLL. Although the treatment landscape of CLL has significantly evolved in recent years, no agent has clearly demonstrated efficacy in patients with treatment-refractory CLL in the long run. To identify new drug targets and mechanisms of drug action in neoplastic B cells, a detailed understanding of the molecular mechanisms of leukemic transformation as well as CLL cell survival is required. In the last decades, studies of genetically modified CLL mouse models in line with CLL patient studies provided a variety of exciting data about BCR and BCR-associated kinases in their role in CLL pathogenesis as well as disease progression. BCR surface expression was identified as a particularly important factor regulating CLL cell survival. Also, BCR-associated kinases were shown to provide a crosstalk of the CLL cells with their tumor microenvironment, which highlights the significance of the cells' milieu in the assessment of disease progression and treatment. In this review, we summarize the major findings of recent CLL mouse as well as patient studies in regard to the BCR signalosome and discuss its relevance in the clinics.

Treatment of Double-Refractory Chronic Lymphocytic Leukemia-An Unmet Clinical Need

Recent years have seen significant improvement in chronic lymphocytic leukemia (CLL) management. Targeting B-cell lymphoma (BCL-2) and Bruton's kinase (BTK) have become the main strategies to restrain CLL activity. These agents are generally well tolerated, but the discontinuation of these therapies happens due to resistance, adverse effects, and Richter's transformation. A growing population of patients who have previously used both BTK inhibitors and BCL2 suffer from the constriction of the following regimens. This review explores the resistance mechanisms for both ibrutinib and venetoclax. Moreover, we present innovative approaches evaluated for treating double-refractory CLL.

Response-adapted, time-limited venetoclax, umbralisib, and ublituximab for relapsed/refractory chronic lymphocytic leukemia

ABSTRACT

Many patients with chronic lymphocytic leukemia (CLL) will develop treatment resistance to Bruton tyrosine kinase (BTK) inhibitors. Phosphatidylinositol-3-kinase (PI3K) inhibitors, including umbralisib, have significant clinical activity in relapsed/refractory CLL, but prolonged exposure is associated with potential toxicities. Owing to the synergistic antitumor effects of combined PI3K and BCL-2 inhibition, we sought to explore the feasibility of response-adapted, time-limited therapy to optimize disease control while mitigating the risks of prolonged treatment. We conducted a phase 1/2 clinical trial to determine the safety and efficacy of venetoclax in combination with umbralisib and the anti-CD20 monoclonal antibody, ublituximab, (U2-VeN) in patients with relapsed/refractory CLL (N = 46) and Richter transformation (N = 5). After 12 cycles, treatment was stopped for patients with CLL who achieved undetectable minimal residual disease (uMRD). Adverse events of special interest included diarrhea in 50% of patients (11% grade 3/4), and aspartate aminotransferase and/or alanine aminotransferase elevation in 15 patients (33%), with 3 (7%) grade 3/4. There were no cases of tumor lysis syndrome related to venetoclax, with outpatient initiation in 96% of patients. The intent-to-treat overall response rate for CLL was 98% with best response of 100% in evaluable patients (42% complete responses). The end-of-treatment rate of uMRD at 10-4 in bone marrow was 77% (30/39), including a 71% uMRD rate among 14 patients refractory to prior BTK inhibitor. Time-limited venetoclax and U2 is safe and highly effective combination therapy for patients with relapsed/refractory CLL including those who have been previously treated with covalent BTK inhibitors. This trial was registered on www.clinicaltrials.gov as #NCT03379051.

Development and Clinical Applications of PI3K/AKT/mTOR Pathway Inhibitors as a Therapeutic Option for Leukemias

Leukemias are hematological neoplasms characterized by dysregulations in several cellular signaling pathways, prominently including the PI3K/AKT/mTOR pathway. Since this pathway is associated with several important cellular mechanisms, such as proliferation, metabolism, survival, and cell death, its hyperactivation significantly contributes to the development of leukemias. In addition, it is a crucial prognostic factor, often correlated with therapeutic resistance. Changes in the PI3K/AKT/mTOR pathway are identified in more than 50% of cases of acute leukemia, especially in myeloid lineages. Furthermore, these changes are highly frequent in cases of chronic lymphocytic leukemia, especially those with a B cell phenotype, due to the correlation between the hyperactivation of B cell receptors and the abnormal activation of PI3Kδ. Thus, the search for new therapies that inhibit the activity of the PI3K/AKT/mTOR pathway has become the objective of several clinical studies that aim to replace conventional oncological treatments that have high rates of toxicities and low specificity with target-specific therapies offering improved patient quality of life. In this review we describe the PI3K/AKT/mTOR signal transduction pathway and its implications in leukemogenesis. Furthermore, we provide an overview of clinical trials that employed PI3K/AKT/mTOR inhibitors either as monotherapy or in combination with other cytotoxic agents for treating patients with various types of leukemias. The varying degrees of treatment efficacy are also reported.

Resisting the Resistance: Navigating BTK Mutations in Chronic Lymphocytic Leukemia (CLL)

Bruton's tyrosine kinase (BTK) plays a key role in the B-cell receptor (BCR) signaling pathway and confers anti-apoptotic and proliferative properties to malignant B-cells in chronic lymphocytic leukemia (CLL). Small molecule BTK inhibitors were designed to bind BTK's active site and block downstream signaling. These drugs have now been used in the treatment of thousands of patients with CLL, the most common form of leukemia in the western hemisphere. However, adverse effects of early generations of BTK inhibitors and resistance to treatment have led to the development of newer, more selective and non-covalent BTK inhibitors. As the use of these newer generation BTK inhibitors has increased, novel BTK resistance mutations have come to light. This review aims to discuss previously known and novel BTK mutations, their mechanisms of resistance, and their relationship with patient treatment. Also discussed here are future studies that are needed to investigate the underlying cause allowing these mutations to occur and how they incite resistance. New treatments on the horizon that attempt to maneuver around these resistance mutations can be met with new resistance mutations, creating an unmet need for patients with CLL. Novel therapies and combinations that address all forms of resistance are discussed.

Synthesis and application of small molecules approved for the treatment of lymphoma

Lymphoma is a form of cancer that impacts the lymphatic system, which plays a crucial role in defending the body against infections and illnesses. It is characterized by the atypical proliferation of lymphocytes, a type of white blood cell, which can form tumors in the lymph nodes, bone marrow, spleen, etc. Lymphoma is usually treated using a combination of targeted therapy, chemotherapy, and radiation therapy. In recent years, there has been a growing interest in the development of new drugs to treat lymphoma, which has led to the discovery of several promising compounds. The primary targets for lymphoma treatment have been identified as Bruton's tyrosine kinase (BTK), phosphoinositide3-kinase (PI3K), histone deacetylase (HDAC), and DNA polymerase (POLA). This review aims to provide an overview of the clinical applications and synthesis of several notable drugs approved to treat lymphoma, to expedite the exploration of more potent novel medications for the management of lymphoma.

Work-Up and Treatment Strategies for Individuals with PIK3CA-Related Disorders: A Consensus of Experts from the Scientific Committee of the Italian Macrodactyly and PROS Association

PIK3CA-related disorders encompass many rare and ultra-rare conditions caused by somatic genetic variants that hyperactivate the PI3K-AKT-mTOR signaling pathway, which is essential for cell cycle control. PIK3CA-related disorders include PIK3CA-related overgrowth spectrum (PROS), PIK3CA-related vascular malformations and PIK3CA-related non-vascular lesions. Phenotypes are extremely heterogeneous and overlapping. Therefore, diagnosis and management frequently involve various health specialists. Given the rarity of these disorders and the limited number of centers offering optimal care, the Scientific Committee of the Italian Macrodactyly and PROS Association has proposed a revision of the most recent recommendations for the diagnosis, molecular testing, clinical management, follow-up, and treatment strategies. These recommendations give insight on molecular diagnosis, eligible samples, preferable sequencing, and validation methods and management of negative results. The purpose of this paper is to promote collaboration between health care centers and clinicians with a joint shared approach. Finally, we suggest the direction of present and future research studies, including new systemic target therapies, which are currently under evaluation in several clinical trials, such as specific inhibitors that can be employed to downregulate the signaling pathway.

Idelalisib (PI3Kδ inhibitor) therapy for patients with relapsed/refractory chronic lymphocytic leukemia: A Swedish nation-wide real-world report on consecutively identified patients

OBJECTIVES

We examined the efficacy and toxicity of the PI3Kδ inhibitor idelalisib in combination with rituximab salvage therapy in consecutively identified Swedish patients with chronic lymphocytic leukemia (CLL).

METHODS AND RESULTS

Thirty-seven patients with relapsed/refractory disease were included. The median number of prior lines of therapy was 3 (range 1-11); the median age was 69 years (range 50-89); 22% had Cumulative Illness Rating Scale (CIRS) >6 and 51% had del(17p)/TP53 mutation. The overall response rate was 65% (all but one was partial response [PR]). The median duration of therapy was 9.8 months (range 0.9-44.8). The median progression-free survival was 16.4 months (95% CI: 10.4-26.3) and median overall survival had not been reached (75% remained alive at 24 months of follow-up). The most common reason for cessation of therapy was colitis (n = 8, of which seven patients experienced grade ≥3 colitis). The most common serious adverse event was grade ≥3 infection, which occurred in 24 patients (65%).

CONCLUSIONS

Our real-world results suggest that idelalisib is an effective and relatively safe treatment for patients with advanced-stage CLL when no other therapies exist. Alternative dosing regimens and new PI3K inhibitors should be explored, particularly in patients who are double-refractory to inhibitors of BTK and Bcl-2.

Exploring and exploiting the host cell autophagy during Mycobacterium tuberculosis infection

Tuberculosis, caused by Mycobacterium tuberculosis, is a fatal infectious disease that prevails to be the second leading cause of death from a single infectious agent despite the availability of multiple drugs for treatment. The current treatment regimen involves the combination of several drugs for 6 months that remain ineffective in completely eradicating the infection because of several drawbacks, such as the long duration of treatment and the side effects of drugs causing non-adherence of patients to the treatment regimen. Autophagy is an intracellular degradative process that eliminates pathogens at the early stages of infection. Mycobacterium tuberculosis's unique autophagy-blocking capability makes it challenging to eliminate compared to usual pathogens. The present review discusses recent advances in autophagy-inhibiting factors and mechanisms that could be exploited to identify autophagy-inducing chemotherapeutics that could be used as adjunctive therapy with the existing first-line anti-TB agent to shorten the duration of therapy and enhance cure rates from multidrug-resistant tuberculosis (MDR-TB) and extreme drug-resistant tuberculosis (XDR-TB).

Targeting phosphoinositide signaling in cancer: relevant techniques to study lipids and novel avenues for therapeutic intervention

Phosphoinositides serve as essential players in numerous biological activities and are critical for overall cellular function. Due to their complex chemical structures, localization, and low abundance, current challenges in the phosphoinositide field include the accurate measurement and identification of specific variants, particularly those with acyl chains. Researchers are intensively developing innovative techniques and approaches to address these challenges and advance our understanding of the impact of phosphoinositide signaling on cellular biology. This article provides an overview of recent advances in the study of phosphoinositides, including mass spectrometry, lipid biosensors, and real-time activity assays using fluorometric sensors. These methodologies have proven instrumental for a comprehensive exploration of the cellular distribution and dynamics of phosphoinositides and have shed light on the growing significance of these lipids in human health and various pathological processes, including cancer. To illustrate the importance of phosphoinositide signaling in disease, this perspective also highlights the role of a family of lipid kinases named phosphatidylinositol 5-phosphate 4-kinases (PI5P4Ks), which have recently emerged as exciting therapeutic targets for cancer treatment. The ongoing exploration of phosphoinositide signaling not only deepens our understanding of cellular biology but also holds promise for novel interventions in cancer therapy.

Relapsed/Refractory Chronic Lymphocytic Leukemia (CLL)

PURPOSE OF REVIEW

There have been significant advances in the treatment of relapsed/refractory chronic lymphocytic leukemia (CLL) over the past two decades. However, the intention of treatment remains control of the disease and delay of progression rather than a cure which remains largely elusive. Considering that CLL is mostly seen in older patients, there are multiple factors that play a role in the selection of CLL beyond the frontline treatment. Here, we review the concept of relapsed CLL, factors that predispose to relapse, and therapeutic options available to this patient population. We also review investigational therapies and provide a framework for selection of therapies in this setting.

RECENT FINDINGS

Targeted therapies with continuous BTK inhibitors (BTKi) or fixed duration venetoclax plus anti-CD20 monoclonal antibody therapy have established superiority over chemoimmunotherapy in relapsed CLL and have become the preferred standard of care treatment. The second-generation more selective BTK inhibitors (acalabrutinib and zanubrutinib) have shown improved safety profile compared to ibrutinib. However, resistance to the covalent BTK inhibitors may emerge and is commonly associated with mutations in BTK or other downstream enzymes. The novel non-covalent BTK inhibitors such as pirtobrutinib (Loxo-305) and nemtabrutinib (ARQ 531) are showing promising activities for relapsed CLL refractory to prior covalent BTKi. Other novel therapies such as chimeric antigen receptor (CAR) T cell therapy have also shown significant activities for relapsed and refractory CLL. Measurable residual disease (MRD) assessment has a growing importance in venetoclax-based limited-duration therapy and there is mounting evidence that MRD negativity improves outcomes. However, it remains to be seen if this will become an established clinically significant endpoint. Further, the optimal sequence of various treatment options remains to be determined. Patients with relapsed CLL now have more options for the treatment of the disease. The choice of therapy is best individualized especially in the absence of direct comparisons of targeted therapies, and the coming years will bring more data on the best sequence of use of the therapeutic agents.

Chronic Lymphocytic Leukemia: Disease Biology

BACKGROUND

B-cell receptor (BCR) signaling is crucial for normal B-cell development and adaptive immunity. In chronic lymphocytic leukemia (CLL), the malignant B cells display many features of normal mature B lymphocytes, including the expression of functional B-cell receptors (BCRs). Cross talk between CLL cells and the microenvironment in secondary lymphatic organs results in BCR signaling and BCR-driven proliferation of the CLL cells. This critical pathomechanism can be targeted by blocking BCR-related kinases (BTK, PI3K, spleen tyrosine kinase) using small-molecule inhibitors. Among these targets, Bruton tyrosine kinase (BTK) inhibitors have the highest therapeutic efficacy; they effectively block leukemia cell proliferation and generally induce durable remissions in CLL patients, even in patients with high-risk disease. By disrupting tissue homing receptor (i.e., chemokine receptor and adhesion molecule) signaling, these kinase inhibitors also mobilize CLL cells from the lymphatic tissues into the peripheral blood (PB), causing a transient redistribution lymphocytosis, thereby depriving CLL cells from nurturing factors within the tissue niches.

SUMMARY

The clinical success of the BTK inhibitors in CLL underscores the central importance of the BCR in CLL pathogenesis. Here, we review CLL pathogenesis with a focus on the role of the BCR and other microenvironment cues.

KEY MESSAGES

(i) CLL cells rely on signals from their microenvironment for proliferation and survival. (ii) These signals are mediated by the BCR as well as chemokine and integrin receptors and their respective ligands. (iii) Targeting the CLL/microenvironment interaction with small-molecule inhibitors provides a highly effective treatment strategy, even in high-risk patients.

Parsaclisib, a PI3Kδ inhibitor, in relapsed and refractory follicular lymphoma (CITADEL-203): a phase 2 study

Background

Parsaclisib, a potent and highly selective PI3Kδ inhibitor, has shown clinical benefit in patients with relapsed or refractory (R/R) B-cell malignancies. This phase 2 study (CITADEL-203; NCT03126019, EudraCT 2017-001624-22) assessed efficacy and safety of parsaclisib monotherapy in patients with R/R follicular lymphoma (FL).

Methods

Patients ≥18 years of age with histologically confirmed R/R FL (grade 1-3a) and prior treatment with ≥2 systemic therapies received parsaclisib 20 mg once daily (QD) for 8 weeks then parsaclisib 20 mg once weekly (weekly dosing group [WG]) or parsaclisib 20 mg QD for 8 weeks then parsaclisib 2.5 mg QD (daily dosing group [DG]); DG was selected for further assessment. Primary endpoint was objective response rate (ORR).

Findings

At data cut-off (January 15, 2021), 126 patients had been treated (WG: n = 23; DG: n = 103). ORR (95% confidence interval [CI]) was 77.7% (68.4-85.3) with a complete response rate (95% CI) of 19.4% (12.3-28.4) in DG; median (95% CI) duration of response was 14.7 months (10.4-not estimable [NE]), median progression-free survival was 15.8 months (11.0-NE), and median overall survival was not reached. The most common any-grade treatment-emergent adverse events (TEAEs) among all treated patients included diarrhoea (n = 48, 38.1%), nausea (n = 31, 24.6%), and cough (n = 28, 22.2%); the most common grade ≥3 TEAEs were diarrhoea (n = 15, 11.9%), neutropenia (n = 13, 10.3%), and colitis (n = 7, 5.6%). Dose interruption, reduction, and discontinuation from TEAEs occurred in 46.8% (n = 59), 17.5% (n = 22), and 23.8% (n = 30) of patients, respectively.

Interpretation

Treatment with parsaclisib demonstrated rapid and durable responses, and a manageable safety profile in patients with R/R FL.

Funding

Incyte Corporation.

PI3K/AKT/mTOR signaling transduction pathway and targeted therapies in cancer

The PI3K/AKT/mTOR (PAM) signaling pathway is a highly conserved signal transduction network in eukaryotic cells that promotes cell survival, cell growth, and cell cycle progression. Growth factor signalling to transcription factors in the PAM axis is highly regulated by multiple cross-interactions with several other signaling pathways, and dysregulation of signal transduction can predispose to cancer development. The PAM axis is the most frequently activated signaling pathway in human cancer and is often implicated in resistance to anticancer therapies. Dysfunction of components of this pathway such as hyperactivity of PI3K, loss of function of PTEN, and gain-of-function of AKT, are notorious drivers of treatment resistance and disease progression in cancer. In this review we highlight the major dysregulations in the PAM signaling pathway in cancer, and discuss the results of PI3K, AKT and mTOR inhibitors as monotherapy and in co-administation with other antineoplastic agents in clinical trials as a strategy for overcoming treatment resistance. Finally, the major mechanisms of resistance to PAM signaling targeted therapies, including PAM signaling in immunology and immunotherapies are also discussed.

Role of microRNAs in Chronic Lymphocytic Leukemia

Chronic Lymphocytic Leukemia (CLL) is the most common form of leukemia in adults, with a highly variable clinical course. Improvement in the knowledge of the molecular pathways behind this disease has led to the development of increasingly specific therapies, such as BCR signaling inhibitors and BCL-2 inhibitors. In this context, the emerging role of microRNAs (miRNAs) in CLL pathophysiology and their possible application in therapy is worth noting. MiRNAs are one of the most important regulatory molecules of gene expression. In CLL, they can act both as oncogenes and tumor suppressor genes, and the deregulation of specific miRNAs has been associated with prognosis, progression, and drug resistance. In this review, we describe the role of the miRNAs that primarily impact the disease, and how these miRNAs could be used as therapeutic tools. Certainly, the use of miRNAs in clinical practice is still limited in CLL. Many issues still need to be solved, particularly regarding their biological and safety profile, even if several studies have suggested their efficacy on the disease, alone or in combination with other drugs.

Targeting N-cadherin (CDH2) and the malignant bone marrow microenvironment in acute leukaemia

This review discusses current research on acute paediatric leukaemia, the leukaemic bone marrow (BM) microenvironment and recently discovered therapeutic opportunities to target leukaemia-niche interactions. The tumour microenvironment plays an integral role in conferring treatment resistance to leukaemia cells, this poses as a key clinical challenge that hinders management of this disease. Here we focus on the role of the cell adhesion molecule N-cadherin (CDH2) within the malignant BM microenvironment and associated signalling pathways that may bear promise as therapeutic targets. Additionally, we discuss microenvironment-driven treatment resistance and relapse, and elaborate the role of CDH2-mediated cancer cell protection from chemotherapy. Finally, we review emerging therapeutic approaches that directly target CDH2-mediated adhesive interactions between the BM cells and leukaemia cells.

Beyond PI3Ks: targeting phosphoinositide kinases in disease

Lipid phosphoinositides are master regulators of almost all aspects of a cell's life and death and are generated by the tightly regulated activity of phosphoinositide kinases. Although extensive efforts have focused on drugging class I phosphoinositide 3-kinases (PI3Ks), recent years have revealed opportunities for targeting almost all phosphoinositide kinases in human diseases, including cancer, immunodeficiencies, viral infection and neurodegenerative disease. This has led to widespread efforts in the clinical development of potent and selective inhibitors of phosphoinositide kinases. This Review summarizes our current understanding of the molecular basis for the involvement of phosphoinositide kinases in disease and assesses the preclinical and clinical development of phosphoinositide kinase inhibitors.

Small-Molecule Compounds Boost CAR-T Cell Therapy in Hematological Malignancies

OPINION STATEMENT

Although chimeric antigen receptor T cell immunotherapy has been successfully applied in patients with hematological malignancies, several obstacles still need to be overcome, such as high relapse rates and side effects. Overcoming the limitations of CAR-T cell therapy and boosting the efficacy of CAR-T cell therapy are urgent issues that must be addressed. The exploration of small-molecule compounds in combination with CAR-T cell therapies has achieved promising success in pre-clinical and clinical studies in recent years. Protein kinase inhibitors, demethylating drugs, HDAC inhibitors, PI3K inhibitors, immunomodulatory drugs, Akt inhibitors, mTOR inhibitors, and Bcl-2 inhibitors exhibited potential synergy in combination with CAR-T cell therapy. In this review, we will discuss the recent application of these combination therapies for improved outcomes of CAR-T cell therapy.

Mitigating Serious Adverse Events in Gene Therapy with AAV Vectors: Vector Dose and Immunosuppression

Gene transfer with high doses of adeno-associated viral (AAV) vectors has resulted in serious adverse events and even death of the recipients. Toxicity could most likely be circumvented by repeated injections of lower and less toxic doses of vectors. This has not been pursued as AAV vectors induce potent neutralizing antibodies, which prevent cell transduction upon reinjection of the same vector. This review discusses different types of immune responses against AAV vectors and how they offer targets for the elimination or inhibition of vector-specific neutralizing antibodies. Such antibodies can be circumvented by using different virus serotypes for sequential injections, they can be removed by plasmapheresis, or they can be destroyed by enzymatic degradation. Antibody producing cells can be eliminated by proteasome inhibitors. Drugs that inhibit T-cell responses, B-cell signaling, or presentation of the vector's antigens to B cells can prevent or reduce induction of AAV-specific antibodies. Combinations of different approaches and drugs are likely needed to suppress or eliminate neutralizing antibodies, which would then allow for repeated dosing. Alternatively, novel AAV vectors with higher transduction efficacy are being developed and may allow for a dose reduction, although it remains unknown if this will completely address the problem of high-dose adverse events.

Metabolomics: A New Era in the Diagnosis or Prognosis of B-Cell Non-Hodgkin's Lymphoma

A wide range of histological as well as clinical properties are exhibited by B-cell non-Hodgkin's lymphomas. These properties could make the diagnostics process complicated. The diagnosis of lymphomas at an initial stage is essential because early remedial actions taken against destructive subtypes are commonly deliberated as successful and restorative. Therefore, better protective action is needed to improve the condition of those patients who are extensively affected by cancer when diagnosed for the first time. The development of new and efficient methods for early detection of cancer has become crucial nowadays. Biomarkers are urgently needed for diagnosing B-cell non-Hodgkin's lymphoma and assessing the severity of the disease and its prognosis. New possibilities are now open for diagnosing cancer with the help of metabolomics. The study of all the metabolites synthesised in the human body is called "metabolomics." A patient's phenotype is directly linked with metabolomics, which can help in providing some clinically beneficial biomarkers and is applied in the diagnostics of B-cell non-Hodgkin's lymphoma. In cancer research, it can analyse the cancerous metabolome to identify the metabolic biomarkers. This review provides an understanding of B-cell non-Hodgkin's lymphoma metabolism and its applications in medical diagnostics. A description of the workflow based on metabolomics is also provided, along with the benefits and drawbacks of various techniques. The use of predictive metabolic biomarkers for the diagnosis and prognosis of B-cell non-Hodgkin's lymphoma is also explored. Thus, we can say that abnormalities related to metabolic processes can occur in a vast range of B-cell non-Hodgkin's lymphomas. The metabolic biomarkers could only be discovered and identified as innovative therapeutic objects if we explored and researched them. In the near future, the innovations involving metabolomics could prove fruitful for predicting outcomes and bringing out novel remedial approaches.

Receptors of immune cells mediates recognition for tumors

Over the last few decades, the immune system has been steered toward eradication of cancer cells with the help of cancer immunotherapy. T cells, B cells, monocytes/macrophages, dendritic cells, T-reg cells, and natural killer (NK) cells are some of the numerous immune cell types that play a significant part in cancer cell detection and reduction of inflammation, and the antitumor response. Briefly stated, chimeric antigen receptors, adoptive transfer and immune checkpoint modulators are currently the subjects of research focus for successful immunotherapy-based treatments for a variety of cancers. This chapter discusses ongoing investigations on the mechanisms and recent developments by which receptors of immune cells especially that of lymphocytes and monocytes/macrophages regulate the detection of immune system leading to malignancies. We will also be looking into the treatment strategies based on these mechanisms.

Gastrointestinal injury induced by immunomodulators: A review article

An increasing number of immunomodulators, either anti-inflammatory or immunity-enhancing, have brought about a revolutionary effect in the management of a variety of autoimmune disorders and malignancies. However, their ability to cause gastrointestinal (GI) injury and induce GI symptoms has been increasingly and unexpectedly recognized. GI injury associated with immunomodulators may demonstrate various histologic and endoscopic patterns. Optimal diagnosis and treatment require a multidisciplinary approach. This review aims to provide an overview of the literature on its pathogenesis, the clinical, endoscopic, and histologic features, and suggested approaches to manage these newly recognized immunomodulator-induced GI adverse effects (AEs). We also reviewed current biomarkers predictive of GI toxicity and potential risk factors to identify susceptible patients. In addition, these immune-mediated AEs were compared with inflammatory bowel disease, a well-documented form of inflammation-driven GI injury. We hope this review will raise awareness and vigilance among clinicians of these entities to increase early diagnosis and rapid referral to specialist care.

Idelalisib inhibits experimental proliferative vitroretinopathy

Proliferative vitreoretinopathy (PVR) is a fibrotic eye disease that develops after rhegmatogenous retinal detachment surgery and open-globe traumatic injury. Idelalisib is a specific inhibitor of phosphoinositide 3-kinase (PI3K) δ. While PI3Kδ is primarily expressed in leukocytes, its expression is also considerably high in retinal pigment epithelial (RPE) cells, which play a crucial part in the PVR pathogenesis. Herein we show that GeoMx Digital Spatial Profiling uncovered strong expression of fibronectin in RPE cells within epiretinal membranes from patients with PVR, and that idelalisib (10 μM) inhibited Akt activation, fibronectin expression and collagen gel contraction induced by transforming growth factor (TGF)-β2 in human RPE cells. Furthermore, we discovered that idelalisib at a vitreal concentration of 10 μM, a non-toxic dose to the retina, prevented experimental PVR induced by intravitreally injected RPE cells in rabbits assessed by experienced ophthalmologists using an indirect ophthalmoscope plus a + 30 D fundus lens, electroretinography, optical coherence tomography and histological analysis. These data suggested idelalisib could be harnessed for preventing patients from PVR.

CD160 receptor in CLL: Current state and future avenues

CD160 is a glycosylphosphatidylinositol (GPI)-anchored cell surface glycoprotein expressed on cytotoxic natural killer (NK) cells and T-cell subsets. It plays a crucial role in the activation of NK-cell cytotoxicity and cytokine production. It also modulates the immune system and is involved in some pathologies, such as cancer. CD160 is abnormally expressed in B-cell chronic lymphocytic leukemia (CLL) but not expressed in normal B lymphocytes. Its expression in CLL enhances tumor cell proliferation and resistance to apoptosis. CD160 is also a potential prognostic marker for the detection of minimal residual disease (MRD) in CLL, which is important for the clinical management of CLL, the prevention of disease relapse, and the achievement of complete remission. In this review, we present an overview of CD160 and its involvement in the pathophysiology of CLL. We also discuss its use as a prognostic marker for the assessment of MRD in CLL.

An Unbiased CRISPR-Cas9 Screening Method for the Identification of Positive and Negative Regulatory Proteins of Cell Adhesion

Mature B-cell lymphomas are highly dependent upon the protective lymphoid organ microenvironment for their growth and survival. Targeting integrin-mediated homing and retention of the malignant B cells in the lymphoid organs, using the Bruton's tyrosine kinase (BTK) inhibitor ibrutinib, is a highly efficacious FDA-approved therapy for chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL), and Waldenström macroglobulinemia (WM). Unfortunately, a significant subset of patients is intrinsically resistant to ibrutinib or will develop resistance upon prolonged treatment. Here, we describe an unbiased functional genomic CRISPR-Cas9 screening method to identify novel proteins involved in B-cell receptor-controlled integrin-mediated adhesion, which provides novel therapeutic targets to overcome ibrutinib resistance. This screening method is highly flexible and can be easily adapted to identify cell adhesion-regulatory proteins and signaling pathways for other stimuli, adhesion molecules, and cell types. Graphical abstract.

NOTCH1 Signalling: A key pathway for the development of high-risk chronic lymphocytic leukaemia

NOTCH1 is a cell surface receptor that releases its intracellular domain as transcription factor upon activation. With the advent of next-generation sequencing, the NOTCH1 gene was found recurrently mutated in chronic lymphocytic leukaemia (CLL). Here, virtually all NOTCH1 mutations affect the protein’s PEST-domain and impair inactivation and degradation of the released transcription factor, thus increasing NOTCH1 signalling strength. Besides sequence alterations directly affecting the NOTCH1 gene, multiple other genomic and non-genomic alterations have by now been identified in CLL cells that could promote an abnormally strong NOTCH1 signalling strength. This renders NOTCH1 one of the key signalling pathways in CLL pathophysiology. The frequency of genomic alterations affecting NOTCH1 signalling is rising over the CLL disease course culminating in the observation that besides TP53 loss, 8q gain and CDKN2A/B loss, NOTCH1 mutation is a hallmark genomic alteration associated with transformation of CLL into an aggressive lymphoma (Richter transformation). Both findings associate de-regulated NOTCH1 signalling with the development of high-risk CLL. This narrative review provides data on the role of NOTCH1 mutation for CLL development and progression, discusses the impact of NOTCH1 mutation on treatment response, gives insight into potential modes of NOTCH1 pathway activation and regulation, summarises alterations that have been discussed to contribute to a de-regulation of NOTCH1 signalling in CLL cells and provides a perspective on how to assess NOTCH1 signalling in CLL samples.

Chemical Constituents of Callistemon subulatus and Their Anti-Pancreatic Cancer Activity against Human PANC-1 Cell Line

An n-hexane extract of Callistemon subulatus was found to exhibit potent cytotoxicity against PANC-1 human pancreatic cancer cells, preferentially under nutrition starvation conditions, with a PC₅₀ value of 6.2 µg/mL. Phytochemical investigation of this bioactive extract resulted in the isolation of fifteen compounds (1–15), including a new compound, subulatone A (–). The structure of compound 1 was elucidated using HRFABMS and NMR spectroscopic analyses. The isolated compounds were tested for their preferential cytotoxicity against the PANC-1 human pancreatic cancer cell line, using an anti-austerity strategy. Among these, myrtucommulone A (2) showed highly potent preferential cytotoxicity, with a PC₅₀ value of 0.28 µM. Myrtucommulone A (2) was found to alter PANC-1 cell morphology, inhibit cell migration, and downregulate the PI3K/Akt/mTOR and autophagy signaling pathways in nutrient-deprived media, leading to cancer cell death. Therefore, myrtucommulone A (2) is a lead compound for anticancer drug development based on an anti-austerity strategy.

Determining drug dose in the era of targeted therapies: playing it (un)safe?

Targeted therapies against phosphatidylinositol 3-kinase (PI3K), Bruton’s tyrosine kinase (BTK), and B-cell lymphoma-2 (BCL-2) are approved for chronic lymphocytic leukemia (CLL). Since approval of the first-in-class drugs, next-generation agents have become available and are continuously under development. While these therapies act on well-characterized molecular targets, this knowledge is only to some extent taken into consideration when determining their dose in phase I trials. For example, BTK occupancy has been assessed in dose-finding studies of various BTK inhibitors, but the minimum doses that result in full BTK occupancy were not determined. Although targeted agents have a different dose–response relationship than cytotoxic agents, which are more effective near the maximum tolerated dose, the traditional 3 + 3 toxicity-driven trial design remains heavily used in the era of targeted therapies. If pharmacodynamic biomarkers were more stringently used to guide dose selection, the recommended phase II dose would likely be lower as compared to the toxicity-driven selection. Reduced drug doses may lower toxicity, which in some cases is severe for these agents, and are supported by retrospective studies demonstrating non-inferior outcomes for patients with clinically indicated dose reductions. Here, we review strategies that were used for dose selection in phase I studies of currently approved and select investigational targeted therapies in CLL, and discuss how our initial clinical experience with targeted therapies have pointed to dose reductions, intermittent dosing, and drug combinations as strategies to overcome treatment intolerance and resistance.

Efficacy and safety of phosphatidylinositol 3-kinase inhibitors in patients with chronic lymphocytic leukemia: a meta-analysis and systematic review

BACKGROUND

Phosphatidylinositol 3-kinase (PI3K) inhibitors demonstrate promising effects in the treatment of relapsed/refractory chronic lymphocytic leukemia (CLL). Emerging evidence of the therapeutic effects of the PI3K inhibitors in various aspects remains controversial.

RESEARCH DESIGN AND METHODS

This meta-analysis was to evaluate the efficacy and safety of PI3K inhibitors based on a synthesis of the data generated by randomized controlled trials (RCTs) of patients with CLL, by searching PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov registry.

RESULTS

Five RCTs with 1593 patients were included. The PI3K inhibitors significantly improved progression-free survival (PFS), the chance of overall response, and partial response than the control arm. Regarding adverse events (AEs), the PI3K inhibitors increased the risk of pyrexia, chills, diarrhea, decreased appetite, vomiting, rash, pneumonia, and upper respiratory tract infection.

CONCLUSIONS

Available evidence showed significant improvements over conventional therapy in PFS of the PI3K inhibitors in patients with CLL, with relatively manageable AEs.

Results of a Prospective Non-Interventional Post-Authorization Safety Study of Idelalisib in Germany

BACKGROUND

In pivotal studies, idelalisib demonstrated remarkable efficacy and manageable tolerability in patients with chronic lymphocytic leukemia (CLL) and follicular lymphoma (FL). This prospective, multicenter, non-interventional post-authorization study assessed the characteristics, clinical management, and outcome of CLL and FL patients receiving idelalisib in routine clinical practice in Germany.

PATIENTS

Observational study in CLL and FL patients treated with idelalisib between September 2015 and December 2020.

RESULTS

A total of 147 patients with CLL and FL were included with a median age of 75 and 71 years, respectively. More than 80% of patients presented with comorbidity and many CLL patients with documented high-risk genetic features, including del(17p)/TP53 mutation or unmutated IGHV. The median progression-free survival (PFS) and overall survival (OS) were not reached in the CLL cohort irrespective of del(17p)/TP53 or unmutated IGHV. The estimated 6-month PFS and OS rates in CLL were 82% and 92%. The estimated 6-month PFS and OS rates for FL were 32.2% and 77.2%. Overall response rates in the CLL and FL cohorts were 70.4% and 36.4%, with the presence of high-risk genetics having no negative impact. No unexpected adverse events were observed. Most frequently reported adverse drug reactions (ADRs) were diarrhea, nausea, pneumonia, rash, and fatigue.

CONCLUSION

This real-world study shows that idelalisib is an effective therapy for CLL and FL, regardless of age and high-risk genetic features, consistent with results from previous clinical trials. Collected safety data and the pattern of ADRs reflect those from previous studies.

Role of Iron and Iron Overload in the Pathogenesis of Invasive Fungal Infections in Patients with Hematological Malignancies

Iron is an essential trace metal necessary for the reproduction and survival of fungal pathogens. The latter have developed various mechanisms to acquire iron from their mammalian hosts, with whom they participate in a continuous struggle for dominance over iron. Invasive fungal infections are an important problem in the treatment of patients with hematological malignancies, and they are associated with significant morbidity and mortality. The diagnosis of invasive clinical infections in these patients is complex, and the treatment, which must occur as early as possible, is difficult. There are several studies that have shown a possible link between iron overload and an increased susceptibility to infections. This link is also relevant for patients with hematological malignancies and for those treated with allogeneic hematopoietic stem cell transplantation. The role of iron and its metabolism in the virulence and pathogenesis of various invasive fungal infections is intriguing, and so far, there is some evidence linking invasive fungal infections to iron or iron overload. Clarifying the possible association of iron and iron overload with susceptibility to invasive fungal infections could be important for a better prevention and treatment of these infections in patients with hematological malignancies.

Impact of the Types and Relative Quantities of IGHV Gene Mutations in Predicting Prognosis of Patients With Chronic Lymphocytic Leukemia

Patients with CLL with mutated IGHV genes (M-CLL) have better outcomes than patients with unmutated IGHVs (U-CLL). Since U-CLL usually express immunoglobulins (IGs) that are more autoreactive and more effectively transduce signals to leukemic B cells, B-cell receptor (BCR) signaling is likely at the heart of the worse outcomes of CLL cases without/few IGHV mutations. A corollary of this conclusion is that M-CLL follow less aggressive clinical courses because somatic IGHV mutations have altered BCR structures and no longer bind stimulatory (auto)antigens and so cannot deliver trophic signals to leukemic B cells. However, the latter assumption has not been confirmed in a large patient cohort. We tried to address the latter by measuring the relative numbers of replacement (R) mutations that lead to non-conservative amino acid changes (Rnc) to the combined numbers of conservative (Rc) and silent (S) amino acid R mutations that likely do not or cannot change amino acids, "(S+Rc) to Rnc IGHV mutation ratio". When comparing time-to-first-treatment (TTFT) of patients with (S+Rc)/Rnc ≤ 1 and >1, TTFTs were similar, even after matching groups for equal numbers of samples and identical numbers of mutations per sample. Thus, BCR structural change might not be the main reason for better outcomes for M-CLL. Since the total number of IGHV mutations associated better with longer TTFT, better clinical courses appear due to the biologic state of a B cell having undergone many stimulatory events leading to IGHV mutations. Analyses of larger patient cohorts will be needed to definitively answer this question.

Idelalisib activates AKT via increased recruitment of PI3Kδ/PI3Kβ to BCR signalosome while reducing PDK1 in post-therapy CLL cells

Idelalisib targets PI3Kδ in the BCR pathway generating only a partial response in CLL patients, indicating that the leukemic cells may have evolved escape signals. Indeed, we detected increased activation of AKT accompanied by upregulation of MYC/BCL2 in post-therapy CLL cells from patients treated with idelalisib/ofatumumab. To unravel the mechanism of increased AKT-activation, we studied the impact of idelalisib on a CLL-derived cell line, MEC1, as a model. After an initial inhibition, AKT-activation level was restored in idelalisib-treated MEC1 cells in a time-dependent manner. As BCAP (B-cell adaptor for PI3K) and CD19 recruit PI3Kδ to activate AKT upon BCR-stimulation, we examined if idelalisib-treatment altered PI3Kδ-recruitment. Immunoprecipitation of BCAP/CD19 from idelalisib-treated MEC1 cells showed increased recruitment of PI3Kδ in association with PI3Kβ, but not PI3Kα or PI3Kγ and that, targeting both PI3Kδ with PI3Kβ inhibited AKT-reactivation. We detected similar, patient-specific recruitment pattern of PI3K-isoforms by BCAP/CD19 in post-idelalisib CLL cells with increased AKT-activation. Interestingly, a stronger inhibitory effect of idelalisib on P-AKT (T308) than S473 was discernible in idelalisib-treated cells despite increased recruitment of PI3Kδ/PI3Kβ and accumulation of phosphatidylinositol-3,4,5-triphosphate; which could be attributed to reduced PDK1 activity. Thus, administration of isoform-specific inhibitors may prove more effective strategy for treating CLL patients.

Targeting metabolic reprogramming in chronic lymphocytic leukemia

Metabolic reprogramming, fundamentally pivotal in carcinogenesis and progression of cancer, is considered as a promising therapeutic target against tumors. In chronic lymphocytic leukemia (CLL) cells, metabolic abnormalities mediate alternations in proliferation and survival compared with normal B cells. However, the role of metabolic reprogramming is still under investigation in CLL. In this review, the critical metabolic processes of CLL were summarized, particularly glycolysis, lipid metabolism and oxidative phosphorylation. The effects of T cells and stromal cells in the microenvironment on metabolism of CLL were also elucidated. Besides, the metabolic alternation is regulated by some oncogenes and tumor suppressor regulators, especially TP53, MYC and ATM. Thus, the agents targeting metabolic enzymes or signal pathways may impede the progression of CLL. Both the inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) statins and the lipoprotein lipase inhibitor orlistat induce the apoptosis of CLL cells. In addition, a series of oxidative phosphorylation inhibitors play important roles in decreasing the proliferation of CLL cells. We epitomized recent advancements in metabolic reprogramming in CLL and discussed their clinical potentiality for innovative therapy options. Metabolic reprogramming plays a vital role in the initiation and progression of CLL. Therapeutic approaches targeting metabolism have their advantages in improving the survival of CLL patients. This review may shed novel light on the metabolism of CLL, leading to the development of targeted agents based on the reshaping metabolism of CLL cells.

NCCN Guidelines® Insights: Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma, Version 3.2022

The treatment landscape of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) has significantly evolved in recent years. Targeted therapy with Bruton's tyrosine kinase (BTK) inhibitors and BCL-2 inhibitors has emerged as an effective chemotherapy-free option for patients with previously untreated or relapsed/refractory CLL/SLL. Undetectable minimal residual disease after the end of treatment is emerging as an important predictor of progression-free and overall survival for patients treated with fixed-duration BCL-2 inhibitor-based treatment. These NCCN Guidelines Insights discuss the updates to the NCCN Guidelines for CLL/SLL specific to the use of chemotherapy-free treatment options for patients with treatment-naïve and relapsed/refractory disease.

Parsaclisib in Japanese patients with relapsed or refractory B-cell lymphoma (CITADEL-111): A phase Ib study

Parsaclisib, a potent, selective, next-generation PI3Kδ inhibitor, has shown clinical benefit in patients with relapsed or refractory B-cell lymphoma. We undertook a phase Ib study (CITADEL-111) evaluating safety, pharmacokinetics, and efficacy of parsaclisib in Japanese patients with relapsed or refractory B-cell malignancies. Patients received oral parsaclisib daily for 8 weeks then once weekly (10-mg dose, n = 3; 20-mg dose, n = 14). Pharmacokinetic samples were collected on days 1, 8, and 15, and efficacy was monitored according to Lugano criteria. At data cut-off (August 14, 2020), 6 patients (35.3%) remained on study treatment and 11 (64.7%) discontinued due to progressive disease (9 [52.9%]) or adverse events (2 [11.8%]). Median duration of treatment was 8.3 (range, 0.3-24.4) months. The most commonly reported nonhematologic adverse events were constipation (6 [35.3%]), nausea, and pyrexia (each 4 [23.5%]). Five patients (29.4%) experienced treatment-emergent new or worsening decreased neutrophils to grade 3 or 4. No treatment-emergent worsening in aminotransferase elevations to grade 3 or 4 were observed. Ten patients (58.8%) required dose interruption and 5 (29.4%) dose reduction. Body weight-normalized parsaclisib exposure was comparable between Japanese and Western patients. Objective response rate was 100% in follicular lymphoma (9 of 9 patients, including complete response in 2 patients [22.2%]) and marginal zone lymphoma (2 of 2 patients), and 16.7% in diffuse large B-cell lymphoma (1 of 6 patients). Results observed in Japanese patients with relapsed or refractory follicular or marginal zone lymphoma support further clinical development of parsaclisib in these patient populations.

A loss-of-adhesion CRISPR-Cas9 screening platform to identify cell adhesion-regulatory proteins and signaling pathways

The clinical introduction of the Bruton’s tyrosine kinase (BTK) inhibitor ibrutinib, which targets B-cell antigen-receptor (BCR)-controlled integrin-mediated retention of malignant B cells in their growth-supportive lymphoid organ microenvironment, provided a major breakthrough in lymphoma and leukemia treatment. Unfortunately, a significant subset of patients is intrinsically resistant or acquires resistance against ibrutinib. Here, to discover novel therapeutic targets, we present an unbiased loss-of-adhesion CRISPR-Cas9 knockout screening method to identify proteins involved in BCR-controlled integrin-mediated adhesion. Illustrating the validity of our approach, several kinases with an established role in BCR-controlled adhesion, including BTK and PI3K, both targets for clinically applied inhibitors, are among the top hits of our screen. We anticipate that pharmacological inhibitors of the identified targets, e.g. PAK2 and PTK2B/PYK2, may have great clinical potential as therapy for lymphoma and leukemia patients. Furthermore, this screening platform is highly flexible and can be easily adapted to identify cell adhesion-regulatory proteins and signaling pathways for other stimuli, adhesion molecules, and cell types.

Targeting integrin-mediated retention of malignant B cells in their protective microenvironment is an efficacious treatment for lymphoma and leukemia. Here, the authors present an unbiased loss-of-adhesion CRISPR screening method, identifying therapeutic targets for these B-cell malignancies.

New Treatment Options for Newly-Diagnosed and Relapsed Chronic Lymphocytic Leukemia

OPINION STATEMENT

The better understanding of the biology of chronic lymphocytic leukemia (CLL) gained over the past decade has led to the development and introduction of several targeted drugs, with an demonstrable improvement in the prognosis for this currently incurable condition. Currently, Bruton's tyrosine kinase (BTK) inhibitors, phosphoinositide 3-kinase (PI3K) inhibitors, venetoclax, and CD20 monoclonal antibodies are the key elements in the treatment of both previously untreated and relapsed/refractory CLL patients. Ibrutinib was the first BTK inhibitor approved for clinical use, and showed excellent efficacy and an acceptable safety profile. Following this, the better-tolerated second-generation irreversible BTK inhibitors acalabrutinib and zanubrutinib have been introduced for the treatment of lymphoid malignancies, and acalabrutinib was approved for CLL. When used as single drugs, BTK inhibitors are given continuously until unacceptable toxicity or disease progression; however, when combined with venetoclax and/or CD20 antibodies, they induce deeper response and can be given for a limited time. Recently, promising new reversible BTK inhibitors pirtobrutinib and nemtabrutinib were discovered, and these seem to be more active and better tolerated than their irreversible predecessors. However, they are in an early phase of development and are not currently approved for CLL. The phosphatidylinositol 3-kinase (PI3K) inhibitors idelalisib and duvelisib are highly effective in patients with relapsed CLL, including high-risk disease. The major limitations for their use are adverse events, mostly of autoimmune origin (hepatitis, enteritis/colitis, and pneumonitis). Otherwise, cellular therapies like allogeneic hematopoietic stem cell transplantation and chimeric antigen receptor (CAR) T cells and bispecific monoclonal antibodies offer promise for patients who have failed BTK inhibitors and venetoclax treatment. In the coming years, it is likely that novel targeted therapies will replace immunochemotherapy regimens in most patients.

PI3K/Akt/mTOR Pathway and Its Role in Cancer Therapeutics: Are We Making Headway?

Cancer is a severe public health issue that is a leading cause of mortality globally. It is also an impediment to improving life expectancy worldwide. Furthermore, the global burden of cancer incidence and death is continuously growing. Current therapeutic options are insufficient for patients, and tumor complexity and heterogeneity necessitate customized medicine or targeted therapy. It is critical to identify potential cancer therapeutic targets. Aberrant activation of the PI3K/AKT/mTOR pathway has a significant role in carcinogenesis. This review summarized oncogenic PI3K/Akt/mTOR pathway alterations in cancer and various cancer hallmarks associated with the PI3K/AKT/mTOR pathway, such as cell proliferation, autophagy, apoptosis, angiogenesis, epithelial-to-mesenchymal transition (EMT), and chemoresistance. Importantly, this review provided recent advances in PI3K/AKT/mTOR inhibitor research. Overall, an in-depth understanding of the association between the PI3K/AKT/mTOR pathway and tumorigenesis and the development of therapies targeting the PI3K/AKT/mTOR pathway will help make clinical decisions.

PI3K Inhibitors for the Treatment of Chronic Lymphocytic Leukemia: Current Status and Future Perspectives

Phosphoinositide 3-kinases (PI3Ks) signaling regulates key cellular processes, such as growth, survival and apoptosis. Among the three classes of PI3K, class I is the most important for the development, differentiation and activation of B and T cells. Four isoforms are distinguished within class I (PI3Kα, PI3Kβ, PI3Kδ and PI3Kγ). PI3Kδ expression is limited mainly to the B cells and their precursors, and blocking PI3K has been found to promote apoptosis of chronic lymphocytic leukemia (CLL) cells. Idelalisib, a selective PI3Kδ inhibitor, was the first-in-class PI3Ki introduced into CLL treatment. It showed efficacy in patients with del(17p)/TP53 mutation, unmutated IGHV status and refractory/relapsed disease. However, its side effects, such as autoimmune-mediated pneumonitis and colitis, infections and skin changes, limited its widespread use. The dual PI3Kδ/γ inhibitor duvelisib is approved for use in CLL patients but with similar toxicities to idelalisib. Umbralisib, a highly selective inhibitor of PI3Kδ and casein kinase-1ε (CK1ε), was found to be efficient and safe in monotherapy and in combination regimens in phase 3 trials in patients with CLL. Novel PI3Kis are under evaluation in early phase clinical trials. In this paper we present the mechanism of action, efficacy and toxicities of PI3Ki approved in the treatment of CLL and developed in clinical trials.

Delivery strategies in treatments of leukemia

Leukemia is a hematological malignancy associated with the uncontrolled proliferation of mutant progenitors, suppressing the production of normal blood cells. Current treatments, including chemotherapy, radiotherapy, and immunotherapy, still lead to unsatisfactory results with a 5 year survival rate of only 30-50%. The poor prognosis is related to both disease relapse and treatment-associated toxicity. Delivery strategies can improve the in vivo pharmacokinetics of drugs, navigating the therapeutics to target cells or the tumor microenvironment and reversing drug resistance, which maximizes tumor elimination and alleviates systematic adverse effects. This review discusses available FDA-approved anti-leukemia drugs and therapies with a focus on the advances in the development of anti-leukemia drug delivery systems. Additionally, challenges in clinical translation of the delivery strategies and future research opportunities in leukemia treatment are also included.

Recognizing Unmet Need in the Era of Targeted Therapy for CLL/SLL: "What's Past Is Prologue" (Shakespeare)

The management of chronic lymphocytic leukemia (CLL) has undergone unprecedented changes over the last decade. Modern targeted therapies are incorporated into clinical practice. Unfortunately, patients have begun to develop resistance or intolerance to multiple classes. Symptomatic patients previously treated with a BTK inhibitor (BTKi) and venetoclax represent a new and rapidly growing unmet need in CLL. Here, we define unmet needs in a modern treatment context. We also critically review the literature for PI3K inhibitors and chemoimmunotherapy and lack of data to support their utility following BTKis and venetoclax. Finally, we suggest opportunities to ensure the continued innovation for patients with CLL.