The mechanism of cancer drug addiction in ALK-positive T-Cell lymphoma

Prolonged Disease Control Despite ALK Inhibitor Discontinuation in Advanced ALK-Positive NSCLC

Introduction

EML4-ALK is an oncogenic driver, seen in around five per cent of advanced non-small-cell lung cancer (NSCLC) patients, which can be targeted with anaplastic lymphoma kinase tyrosine kinase inhibitors with great response rates. Disease flare refers to sudden rapid disease worsening on tyrosine kinase inhibitors (TKI) discontinuation, which is associated with shorter survival and worse outcomes. Here, we review cases previously published in the literature where patients developed disease flares, and contrast this with our patients who had prolonged survival despite TKI discontinuation.

Case description

We report three different patients with advanced ALK-positive NSCLC seen at our institute, who had EML4-ALK translocation variant 1 oncogenic driver on next-generation sequencing. They received treatment with several different ALK inhibitors before opting to discontinue TKI. They were able to come off TKI safely without developing disease flare and had prolonged survival.

Discussion

Shorter time to progression on TKI, presence of symptoms with disease progression or central nervous system/pleural metastasis have been previously linked with development of flare, although this was not seen in our case series. Tumour response at the time of treatment discontinuation, line of therapy, overall disease burden, fusion variant and co-alteration status can affect the prognosis of these patients after ALK TKI cessation. In particular, variant 1 and wild-type TP53 status may be a suitable patient population for dose optimisation strategies. Intermittent TKI dosing strategies may help to avoid acquiring resistance mutations and prevent long-term treatment toxicities.

Conclusion

It is important for clinicians to identify patients at risk for developing disease flare on TKI discontinuation to improve outcomes. Intermittent TKI dosing strategies require further investigation.

LEARNING POINTS

Patients who develop disease flare after cessation have poor survival and worse outcomes.Certain phenotypic and molecular characteristics of the tumour may help clinicians identify which patients are likely and which are unlikely to develop disease flare on TKI discontinuation.Advanced ALK-positive NSCLC with variant 1 and wild-type TP53 may be a suitable patient population for intermittent TKI dosing investigations.

The road less traveled: activating an oncogenic kinase

Elevated phosphoinositide 3-kinase (PI3K) activity in human tumors has prompted widespread efforts to develop chemical PI3K inhibitors for oncology indications. In an innovative new study, Gong et al. report the discovery of a highly selective activator of the PI3Kα isoform, with promising activity in assays of nerve regrowth and cardioprotection from ischemia-reperfusion injury (IRI).

Drug addiction unveils a repressive methylation ceiling in EZH2-mutant lymphoma

Drug addiction, a phenomenon where cancer cells paradoxically depend on continuous drug treatment for survival, has uncovered cell signaling mechanisms and cancer codependencies. Here we discover mutations that confer drug addiction to inhibitors of the transcriptional repressor polycomb repressive complex 2 (PRC2) in diffuse large B-cell lymphoma. Drug addiction is mediated by hypermorphic mutations in the CXC domain of the catalytic subunit EZH2, which maintain H3K27me3 levels even in the presence of PRC2 inhibitors. Discontinuation of inhibitor treatment leads to overspreading of H3K27me3, surpassing a repressive methylation ceiling compatible with lymphoma cell survival. Exploiting this vulnerability, we show that inhibition of SETD2 similarly induces the spread of H3K27me3 and blocks lymphoma growth. Collectively, our findings demonstrate that constraints on chromatin landscapes can yield biphasic dependencies in epigenetic signaling in cancer cells. More broadly, we highlight how approaches to identify drug addiction mutations can be leveraged to discover cancer vulnerabilities.

Targeting CCR7-PI3Kγ overcomes resistance to tyrosine kinase inhibitors in ALK-rearranged lymphoma

Anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKIs) show potent efficacy in several ALK-driven tumors, but the development of resistance limits their long-term clinical impact. Although resistance mechanisms have been studied extensively in ALK-driven non-small cell lung cancer, they are poorly understood in ALK-driven anaplastic large cell lymphoma (ALCL). Here, we identify a survival pathway supported by the tumor microenvironment that activates phosphatidylinositol 3-kinase γ (PI3K-γ) signaling through the C-C motif chemokine receptor 7 (CCR7). We found increased PI3K signaling in patients and ALCL cell lines resistant to ALK TKIs. PI3Kγ expression was predictive of a lack of response to ALK TKI in patients with ALCL. Expression of CCR7, PI3Kγ, and PI3Kδ were up-regulated during ALK or STAT3 inhibition or degradation and a constitutively active PI3Kγ isoform cooperated with oncogenic ALK to accelerate lymphomagenesis in mice. In a three-dimensional microfluidic chip, endothelial cells that produce the CCR7 ligands CCL19/CCL21 protected ALCL cells from apoptosis induced by crizotinib. The PI3Kγ/δ inhibitor duvelisib potentiated crizotinib activity against ALCL lines and patient-derived xenografts. Furthermore, genetic deletion of CCR7 blocked the central nervous system dissemination and perivascular growth of ALCL in mice treated with crizotinib. Thus, blockade of PI3Kγ or CCR7 signaling together with ALK TKI treatment reduces primary resistance and the survival of persister lymphoma cells in ALCL.

Holistic View of ALK TKI Resistance in ALK-Positive Anaplastic Large Cell Lymphoma

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase expressed at early stages of normal development and in various cancers including ALK-positive anaplastic large cell lymphoma (ALK+ ALCL), in which it is the main therapeutic target. ALK tyrosine kinase inhibitors (ALK TKIs) have greatly improved the prognosis of ALK+ALCL patients, but the emergence of drug resistance is inevitable and limits the applicability of these drugs. Although various mechanisms of resistance have been elucidated, the problem persists and there have been relatively few relevant clinical studies. This review describes research progress on ALK+ ALCL including the application and development of new therapies, especially in relation to drug resistance. We also propose potential treatment strategies based on current knowledge to inform the design of future clinical trials.

Resistance to Targeted Agents Used to Treat Paediatric ALK-Positive ALCL

Simple Summary

In general, the non-Hodgkin lymphoma (NHL), anaplastic large cell lymphoma (ALCL) diagnosed in childhood has a good survival outcome when treated with multi-agent chemotherapy. However, side effects of treatment are common, and outcomes are poorer after relapse, which occurs in up to 30% of cases. New drugs are required that are more effective and have fewer side effects. Targeted therapies are potential solutions to these problems, however, the development of resistance may limit their impact. This review summarises the potential resistance mechanisms to these targeted therapies.

Abstract

Non-Hodgkin lymphoma (NHL) is the third most common malignancy diagnosed in children. The vast majority of paediatric NHL are either Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL), anaplastic large cell lymphoma (ALCL), or lymphoblastic lymphoma (LL). Multi-agent chemotherapy is used to treat all of these types of NHL, and survival is over 90% but the chemotherapy regimens are intensive, and outcomes are generally poor if relapse occurs. Therefore, targeted therapies are of interest as potential solutions to these problems. However, the major problem with all targeted agents is the development of resistance. Mechanisms of resistance are not well understood, but increased knowledge will facilitate optimal management strategies through improving our understanding of when to select each targeted agent, and when a combinatorial approach may be helpful. This review summarises currently available knowledge regarding resistance to targeted therapies used in paediatric anaplastic lymphoma kinase (ALK)-positive ALCL. Specifically, we outline where gaps in knowledge exist, and further investigation is required in order to find a solution to the clinical problem of drug resistance in ALCL.