Crizotinib reduces the rate of dark adaptation in the rat retina independent of ALK inhibition

Neuro-ophthalmic complications of modern anti-cancer drugs

PURPOSE

Targeted cancer therapies have been responsible for a dramatic shift in treatment strategies for cancer, and the number of drugs, classes, and indications are continually growing. Neuro-ophthalmic complications of these medications are an uncommon but important subset of adverse events which profoundly impact vision. This review aims to collate studies and reports of known neuro-ophthalmic complications of targeted therapies and describe their management.

METHODS

The anti-cancer drugs included in the review were any drugs targeting specific molecules involved in the cancer disease process. PubMed, EMBASE, and Web of Science were searched using the generic names of each drug and keywords of neuro-ophthalmic conditions. The prescribing information published by the US Food and Drug Administration (FDA) for each drug was also reviewed.

RESULTS

Several classes of targeted anti-cancer drugs were found to cause neuro-ophthalmic adverse effects. Immune checkpoint inhibitors are responsible for a raft of immune-related adverse events such as optic neuritis, ischemic optic neuropathy, PRES, and myasthenia gravis. Therapies with anti-VEGF activity can provoke posterior reversible leukoencephalopathy, which commonly presents with visual loss and can be fatal if not treated promptly. Inhibitors of BCR-ABL1, VEGF, ALK, and proteasomes have all been linked to optic nerve disorders which can have debilitating consequences for vision.

CONCLUSION

The neuro-ophthalmic complications of modern anti-cancer drugs can limit or necessitate the withdrawal of these life-prolonging medications. Ophthalmologists should be alert for neuro-ophthalmic complications in these medications to facilitate prompt diagnosis and treatment and reduce the risk of severe and permanent consequences.

Bilateral optic neuropathy associated with lorlatinib monotherapy for ALK-positive metastatic lung adenocarcinoma

Purpose

This report details the characteristics of a case of bilateral optic neuropathy during treatment with oral lorlatinib for ALK-positive metastatic adenocarcinoma of the lung.

Observations

A 57-year-old woman with metastatic adenocarcinoma of the lung receiving treatment with lorlatinib presented to the ophthalmology urgent care with bilateral loss of vision that had progressed to no light perception over the previous 2 weeks. She was hospitalized for an extensive autoimmune, infectious, neoplastic, and paraneoplastic workup, which revealed enhancement of both optic nerves extending up to the optic chiasm and an area of restricted diffusion in the splenium of the corpus callosum on MRI. Lorlatinib was discontinued by her oncologist and she received treatment with five days of pulse-dose intravenous solumedrol as well as five days of plasmapheresis with gradual improvement in her vision. In follow-up, her vision had improved to 20/40 and 20/30.

Conclusion and importance

There have been few reports describing vision loss associated with lorlatinib, an ALK/ROS1 targeted tyrosine kinase inhibitor used to treat metastatic lung adenocarcinoma. This report details the characteristics of a case of bilateral retrobulbar optic neuropathy as well as the treatment and recovery of such a case. Further exploration is needed in order to improve our understanding of the pathogenesis of this rare but potentially devastating adverse effect.

Sex-related differences in retinal function in Wistar rats: implications for toxicity and safety studies

Introduction: Wistar Han rats are a preferred strain of rodents for general toxicology and safety pharmacology studies in drug development. In some of these studies, visual functional tests that assess for retinal toxicity are included as an additional endpoint. Although the influence of gender on human retinal function has been documented for more than 6 decades, preclinically it is still uncertain if there are differences in retinal function between naïve male and female Wistar Han rats. Methods: In this study, sex-related differences in the retinal function were quantified by analyzing electroretinography (ERG) in 7-9-week-old (n = 52 males and 51 females) and 21-23-week-old Wistar Han rats (n = 48 males and 51 females). Optokinetic tracking response, brainstem auditory evoked potential, ultrasonic vocalization and histology were tested and evaluated in a subset of animals to investigate the potential compensation mechanisms of spontaneous blindness. Results/Discussion: Absence of scotopic and photopic ERG responses was found in 13% of 7-9-week-old (7/52) and 19% of 21-23-week-old males (9/48), but none of female rats (0/51). The averaged amplitudes of rod- and cone-mediated ERG b-wave responses obtained from males were significantly smaller than the amplitudes of the same responses from age-matched females (-43% and -26%, respectively) at 7-9 weeks of age. There was no difference in the retinal and brain morphology, brainstem auditory responses, or ultrasonic vocalizations between the animals with normal and abnormal ERGs at 21-23 weeks of age. In summary, male Wistar Han rats had altered retinal responses, including a complete lack of responses to test flash stimuli (i.e., blindness), when compared with female rats at 7-9 and 21-23 weeks of age. Therefore, sex differences should be considered when using Wistar Han rats in toxicity and safety pharmacology studies with regards to data interpretation of retinal functional assessments.

The Impact of Systemic Medications on Retinal Function

This study will provide a thorough review of systemic (and select intravitreal) medications, along with illicit drugs that are capable of causing various patterns of retinal toxicity. The diagnosis is established by taking a thorough medication and drug history, and then by pattern recognition of the clinical retinal changes and multimodal imaging features. Examples of all of these types of toxicity will be thoroughly reviewed, including agents that cause retinal pigment epithelial disruption (hydroxychloroquine, thioridazine, pentosan polysulfate sodium, dideoxyinosine), retinal vascular occlusion (quinine, oral contraceptives), cystoid macular edema/retinal edema (nicotinic acid, sulfa-containing medications, taxels, glitazones), crystalline deposition (tamoxifen, canthaxanthin, methoxyflurane), uveitis, miscellaneous, and subjective visual symptoms (digoxin, sildenafil). The impact of newer chemotherapeutics and immunotherapeutics (tyrosine kinase inhibitor, mitogen-activated protein kinase kinase, checkpoint, anaplastic lymphoma kinase, extracellular signal-regulated kinase inhibitors, and others), will also be thoroughly reviewed. The mechanism of action will be explored in detail when known. When applicable, preventive measures will be discussed, and treatment will be reviewed. Illicit drugs (cannabinoids, cocaine, heroin, methamphetamine, alkyl nitrite), will also be reviewed in terms of the potential impact on retinal function.

Introduction of gloved hand to cage induces 22-kHz ultrasonic vocalizations in male albino rats

Rodents emit ultrasonic vocalizations (USVs) above the human hearing threshold of ~ 20 kHz to communicate emotional states and to coordinate their social interactive behavior. Twenty-two kHz USVs emitted by adult rats have been reported in a variety of aversive social and behavioral situations. They occur not only under painful or restraining conditions but can also be evoked by gentle cutaneous touch or airflow. This study aimed to test if placement of a human hand in a cage can evoke 22-kHz USVs. It was found that 36% of the adult male Sprague-Dawley and 13% of the adult male Wistar Han rats emitted 22-kHz USVs when a gloved hand was introduced into the cages. Average vocalization onset latencies were 5.0 ± 4.4 s (Sprague-Dawley) and 7.4 ± 4.0 s (Wistar Han) and the USVs had a stable frequency (22 kHz) across the calls, ranging from 0.1 to 2.3 seconds in duration. Surprisingly, no 22-kHz USVs were found in any female Wistar Han rats tested. To further explore the mechanisms underlying this observation, we compared retinal function, basal serum corticosterone, and testosterone levels between the 22-kHz USV responders and non-responders. None of these parameters or endpoints showed any significant differences between the two cohorts. The results suggest that the introduction of a gloved-hand inside the cage can trigger adult male albino rats to emit 22-kHz ultrasonic vocalizations. This response should be considered in USV studies and animal welfare.

ROS1-dependent cancers - biology, diagnostics and therapeutics

The proto-oncogene ROS1 encodes a receptor tyrosine kinase with an unknown physiological role in humans. Somatic chromosomal fusions involving ROS1 produce chimeric oncoproteins that drive a diverse range of cancers in adult and paediatric patients. ROS1-directed tyrosine kinase inhibitors (TKIs) are therapeutically active against these cancers, although only early-generation multikinase inhibitors have been granted regulatory approval, specifically for the treatment of ROS1 fusion-positive non-small-cell lung cancers; histology-agnostic approvals have yet to be granted. Intrinsic or extrinsic mechanisms of resistance to ROS1 TKIs can emerge in patients. Potential factors that influence resistance acquisition include the subcellular localization of the particular ROS1 oncoprotein and the TKI properties such as the preferential kinase conformation engaged and the spectrum of targets beyond ROS1. Importantly, the polyclonal nature of resistance remains underexplored. Higher-affinity next-generation ROS1 TKIs developed to have improved intracranial activity and to mitigate ROS1-intrinsic resistance mechanisms have demonstrated clinical efficacy in these regards, thus highlighting the utility of sequential ROS1 TKI therapy. Selective ROS1 inhibitors have yet to be developed, and thus the specific adverse effects of ROS1 inhibition cannot be deconvoluted from the toxicity profiles of the available multikinase inhibitors. Herein, we discuss the non-malignant and malignant biology of ROS1, the diagnostic challenges that ROS1 fusions present and the strategies to target ROS1 fusion proteins in both treatment-naive and acquired-resistance settings.

Ocular and orbital side effects of ALK inhibitors: a review article

ALK inhibitors are a new group of tyrosine kinase inhibitors, highly efficient in the treatment of non-small-cell lung carcinoma. However, these targeted therapies can induce various adverse effects, including ocular toxicity. To date, few articles reporting ophthalmological side effects of ALK inhibitors have been published. In this review, we aim to describe the different side effects and to collect information regarding the causes behind the discrepancy between the reported rates of visual disorders. Frequent ocular side effects of ALK inhibitors included flashes, post-flashbulb effect, stripes, photopsia, accommodation disorder, presbyopia, reduced visual acuity and blurred vision. Optic neuropathy, vitreous floaters, diplopia, cataract and macular edema were also reported.

Effects of Sodium Lighting On Circadian Rhythms in Rats

Rodent studies often must be conducted during an animal's active phase (that is, in darkness) yet also during a typical day shift for staff. Low-pressure sodium lighting (LPSL), to which human retinas are more sensitive than rodents' at low intensity, has been used to facilitate study conduct in dark phase. The assumption was that LPSL would be equivalent to total darkness due to low rodent retinal sensitivity but provide enough lighting for safe technical manipulations due to higher human retinal sensitivity. Unlike other light sources, LPSL has been tested for effects on circadian rhythm specific to locomotive activities in albino mice. Whether LPSL affects circadian rhythms in rats is unknown. In this study, circadian endpoints were derived from body temperature and locomotor activity via telemeters in 8 adult male Wistar rats. When moved from a 12:12-h white-light (that is, cold white fluorescent light):dark (LD) cycle to a 12:12-h white-light:sodium-light cycle, rats demonstrated free-running and disrupted circadian rhythms (that is, lengthened circadian period and reduced circadian robustness and amplitude). Body temperature and locomotor activity were significantly lower in the LPSL phase as compared with dark phase under the baseline condition. When exposed to a 12:12 h sodium-light:dark (SD) cycle, rats entrained with a circadian period similar to 12:12-h white-light:dark (LD), but significantly different from the period under constant darkness (DD). Circadian onset and acrophase were delayed under SD compared with LD. When illuminated with a LPSL pulse under DD, rats showed phase shifts similar to white-light pulse effects, consistent with the phase response curve. To determine whether the image-forming photoreceptors are involved in this process, we used electroretinography. Compared with white light, 589-nm light generated during electroretinography elicited rod photoreceptors responses with longer latency and cone photoreceptor responses with lower amplitude. These results indicate that LPSL is a weaker zeitgeber than white light and may alter the circadian system in rats. Furthermore, because LPSL appeared to be visible to rats, it may not be an appropriate substitute for actual darkness.

Safety issues with the ALK inhibitors in the treatment of NSCLC: A systematic review

INTRODUCTION

Oral tyrosine kinase inhibitors targeting the chromosomal rearrangements of the anaplastic lymphoma kinase gene (ALK) in non-small cell lung cancer (NSCLC) were associated with superior clinical outcome. Tyrosine Kinase inhibitors (TKIs) are known to have peculiar toxicity profile, hence, increasing awareness to the safety profile of ALK inhibitors is essential.

METHODS

A comprehensive systematic review of literature has been conducted to include prospective trials that used the ALK inhibitors Crizotinib, Ceritinib, Alectinib, Brigatinib and Lorlatinib in patients with advanced NSCLC and have available efficacy and toxicity results.

RESULTS

A total of 14 studies including 2793 patients were considered eligible for our review and included two phase IB, seven phase II and five phase III studies. The most common adverse events (AEs) observed with ALK inhibitors were gastrointestinal (GI) toxicities as nausea (up to 83%), vomiting (up to 67%) and diarrhea (up to 86%), elevation of liver enzymes occurred in up to 60% and fatigue (up to 43%). There were differences in the toxicity patterns between the different ALK inhibitors with more GI and hepatic toxicities with Ceritinib, more visual disorders with Crizotinib, more dysgeusia with crizotinib and Alectinib and possibly more respiratory complications with Brigatinib. Most of the AEs were low grade and treatment-related deaths were associated with ALK inhibitors in 0-1% of patients.

CONCLUSION

Most of adverse effects of ALKi can be managed efficiently via dose modifications or interruptions. Timely identification of each ALKi pattern of toxicity can prevent treatment-related morbidity and mortality in this palliative setting.

Meta-analysis of incidence and risk of severe adverse events and fatal adverse events with crizotinib monotherapy in patients with ALK-positive NSCLC

Background

Numerous clinical trials show crizotinib has promising efficacy for anaplastic lymphoma kinase (ALK) positive non-small cell lung cancer (NSCLC) patients which trigger the substitution of traditional chemotherapy to be the current standard first-line treatment for these patients. Conversely, few reports systematically analyze toxicity of crizotinib. Hence, we performed a first meta-analysis to determine the risk of crizotinib-related severe adverse events (SAEs) and fatal adverse events (FAEs) in ALK positive NSCLC patients.

Materials and Methods

A systematic literature search was conducted through December 2016 to identify clinical trials that reported crizotinib monotherapy in ALK-positive NSCLC patients. Data on crizotinib-related SAEs and FAEs were extracted from each study and pooled to determine the overall incidence and risk. Random-effects or fixed-effects models were conducted to calculate the summary incidence, relative risk (RR), and 95% CIs on basis of the heterogeneity of included studies.

Results

1,924 patients from 11 clinical trials were included. The overall incidence of SAEs and FAEs with crizotinib was 19.9% (95% CI, 14.1% to 23.7%; P < 0.001) and 1.4% (95% CI, 0.9% to 2.1%; P < 0.001), respectively. Meanwhile, Asian patients have lower incidence of SAEs (11.5%, 95% CI: 7.9% to 16.5%). However, significant differences of SAEs (RR: 0.97, 95% CI, 0.79 to 1.18; P = 0.76) and FAEs (RR: 2.24, 95% CI, 0.49 to 10.30; P = 0.30) were not detected between crizotinib monotherapy and chemotherapy.

Conclusions

Crizotinib may not increase the risk of SAEs and FAEs in patients with ALK positive NSCLC compared with chemotherapy.

Ocular safety assessment of sodium iodate in cynomolgus monkeys

Although sodium iodate (NaIO3)-induced retinal injury model has been widely used in rodents, its application in large animal species has encountered variation in retinal toxicity. NaIO3 induced retinal degeneration and functional changes in sheep, but not in swine. In monkeys, administration of NaIO3 via a carotid artery affected only the cell function of ipsilateral retinal pigment epithelium. The aim of the present study was to identify the dosage and route of NaIO3 administration resulting in morphologic and functional retinal changes in cynomolgus monkeys. Separate groups of animals received NaIO3 intravenously in three different dosing paradigms. Vehicle control animals received phosphate-buffered saline. At selected time points following dosing, flash electroretinograms (ERGs) were recorded followed by necropsy. The eyes were examined microscopically post-necropsy and the levels of circulating microRNA-183 cluster were evaluated in the blood samples collected on days 1, 4, and 5 postdose. A statistically significant reduction in both scotopic a-wave and scotopic and photopic b-wave signals ( p < 0.05) were observed between the ERG signals acquired from NaIO3-treated and vehicle control animals, coupled with time-dependent elevations in plasma miR-183 cluster. Mild to moderate retinal degeneration was observed in the outer layer of the retina, which correlated well with the functional and clinical observations. There were no statistically significant differences in scotopic oscillatory potentials. These findings suggest that intravenous injection of sublethal NaIO3 markedly damaged the cone and rod photoreceptors both functionally and morphologically, and plasma miR-183 reflected the retinal toxicity in those animals with moderate retinal damage.

Central nervous system involvement in ALK-rearranged NSCLC: promising strategies to overcome crizotinib resistance

INTRODUCTION

ALK rearranged Non Small Cell Lung Cancers (NSCLCs) represent a distinct subgroup of patients with peculiar clinic-pathological features. These patients exhibit dramatic responses when treated with the ALK tyrosine kinase inhibitor Crizotinib, albeit Central Nervous System (CNS) activity is much less impressive than that observed against extracranial lesions. CNS involvement has become increasingly observed in these patients, given their prolonged survival. Several novel generation ALK inhibitors have been developing to increase CNS penetration and to provide more complete ALK inhibition..

AREAS COVERED

The CNS activity of Crizotinib and novel generation ALK inhibitors will be summarized in this review, evaluating the strengths and weaknesses of the therapeutic strategies developed to date in this specific subgroup of NSCLCs with a look towards the future. Expert commentary: In the next few years, the results of ongoing comparative head-to-head trials will provide the definitive conclusions on the optimal treatment sequence in ALK-rearranged NSCLCs. Moreover, ongoing clinical trials with novel-generation ALK inhibitors will produce more evidences on the best approach in the growing number of ALK-positive NSCLCs with CNS involvement.

Crizotinib-Induced Abnormal Signal Processing in the Retina

Molecular target therapy for cancer is characterized by unique adverse effects that are not usually observed with cytotoxic chemotherapy. For example, the anaplastic lymphoma kinase (ALK)-tyrosine kinase inhibitor crizotinib causes characteristic visual disturbances, whereas such effects are rare when another ALK-tyrosine kinase inhibitor, alectinib, is used. To elucidate the mechanism responsible for these visual disturbances, the responses to light exhibited by retinal ganglion cells treated with these agents were evaluated using a C57BL6 mouse ex vivo model. Both crizotinib and alectinib changed the firing rate of ON and OFF type retinal ganglion cells. However, the ratio of alectinib-affected cells (15.7%) was significantly lower than that of crizotinib-affected cells (38.6%). Furthermore, these drugs changed the response properties to light stimuli of retinal ganglion cells in some of the affected cells, i.e., OFF cells responded to both ON and OFF stimuli, etc. Finally, the expressions of ALK (a target receptor of both crizotinib and alectinib) and of MET and ROS1 (additional target receptors of crizotinib) were observed at the mRNA level in the retina. Our findings suggest that these drugs might target retinal ganglion cells and that the potency of the drug actions on the light responses of retinal ganglion cells might be responsible for the difference in the frequencies of visual disturbances observed between patients treated with crizotinib and those treated with alectinib. The present experimental system might be useful for screening new molecular target agents prior to their use in clinical trials.

A safety assessment of crizotinib in the treatment of ALK-positive NSCLC patients

INTRODUCTION

In the past decade, the treatment of NSCLC has been revolutionized by the discovery of key oncogenic driver mutations and the therapies that specifically target these mutations. Crizotinib has been shown to be an inhibitor of MET, anaplastic lymphoma kinase (ALK) and ROS1 receptor tyrosine kinases, and is FDA approved for ALK inhibition. Crizotinib is effective in NSCLC that harbors ALK translocations resulting in overexpression of oncogenic ALK fusion proteins.

AREAS COVERED

This paper will review crizotinib as a treatment for ALK-positive NSCLC. It will discuss the drug's adverse events, drug-drug interactions and other important clinical and safety information related to crizotinib.

EXPERT OPINION

Compared to standard chemotherapy, crizotinib shows improved progression-free survival in ALK-positive NSCLC, with patient's reporting improved quality of life. However, certain adverse events are more frequent with crizotinib versus standard chemotherapy and must be monitored for closely. The most common adverse events include ocular and gastrointestinal disturbances, cardiac and endocrine abnormalities, and peripheral edema. Many, though not all, of these side effects are likely due to the multiple tyrosine kinases inhibited by crizotinib, and will likely improve with second- and third-generation inhibitors that inhibit ALK more specifically.