Bridging the maytansine and vinca sites: Cryptophycins target ß-tubulin's T5-loop.

Cryptophycins are microtubule-targeting agents (MTAs) that belong to the most potent antimitotic compounds known to date; however, their exact molecular mechanism of action remains unclear. Here, we present the 2.2 Å resolution X-ray crystal structure of a potent cryptophycin derivative bound to the αß-tubulin heterodimer. The structure addresses conformational issues present in a previous 3.3 Å resolution cryo-electron microscopy structure of cryptophycin-52 bound to the maytansine site of ß-tubulin. It further provides atomic details on interactions of cryptophycins, which had not been described previously, including ones that are in line with structure-activity relationship studies. Interestingly, we discovered a second cryptophycin-binding site that involves the T5-loop of ß-tubulin, a critical secondary structure element involved in the exchange of the guanosine nucleotide and in the formation of longitudinal tubulin contacts in microtubules. Cryptophycins are the first natural ligands found to bind to this new "ßT5-loop site" that bridges the maytansine and vinca sites. Our results offer unique avenues to rationally design novel MTAs with the capacity to modulate T5-loop dynamics and to simultaneously engage multiple ß-tubulin binding sites.

Computational Approaches to the Rational Design of Tubulin-Targeting Agents.

Microtubules are highly dynamic polymers of α,ß-tubulin dimers which play an essential role in numerous cellular processes such as cell proliferation and intracellular transport, making them an attractive target for cancer and neurodegeneration research. To date, a large number of known tubulin binders were derived from natural products, while only one was developed by rational structure-based drug design. Several of these tubulin binders show promising in vitro profiles while presenting unacceptable off-target effects when tested in patients. Therefore, there is a continuing demand for the discovery of safer and more efficient tubulin-targeting agents. Since tubulin structural data is readily available, the employment of computer-aided design techniques can be a key element to focus on the relevant chemical space and guide the design process. Due to the high diversity and quantity of structural data available, we compiled here a guide to the accessible tubulin-ligand structures. Furthermore, we review different ligand and structure-based methods recently used for the successful selection and design of new tubulin-targeting agents.

Maytansinol Functionalization: Towards Useful Probes for Studying Microtubule Dynamics.

Invited for the cover of this issue are the groups of Professors Passarella and Pieraccini at the University of Milan, in collaboration with some of the members of TubInTrain consortium. The image depicts work with the elements of nature, in particular the destabilising effect of maytansinol (the constellation) on microtubules (the trees). Read the full text of the article at 10.1002/chem.202203431.

Intracranial Hypertension Associated With Testosterone Therapy In Female-To-Male Transgender Patients: A Case Report And Literature Review.

We highlight a case of intracranial hypertension secondary to exogenous testosterone in a female-to-male transgender patient and present a systematic review of similar cases. Our review identified 19 female-to-male transgender individuals with intracranial hypertension. The mean age was 24.2 years and most common presenting symptom was headache (78.9% of patients). The most frequently associated ocular symptoms were transient visual obscurations (42.1%) and blurred vision (21.1%). Onset of symptoms occurred concurrently with exogenous testosterone therapy in 89.5% of the patients. The most common treatments were acetazolamide (89.5%), topiramate (31.6%), and alteration in hormone regimen (21.1%); four cases required surgery. These findings aid clinicians treating intracranial hypertension in patients undergoing gender affirmation therapy in a conscientious, patient-centered manner.

Maytansinol Functionalization: Towards Useful Probes for Studying Microtubule Dynamics.

Maytansinoids are a successful class of natural and semisynthetic tubulin binders, known for their potent cytotoxic activity. Their wider application as cytotoxins and chemical probes to study tubulin dynamics has been held back by the complexity of natural product chemistry. Here we report the synthesis of long-chain derivatives and maytansinoid conjugates. We confirmed that bulky substituents do not impact their high activity or the scaffold's binding mode. These encouraging results open new avenues for the design of new maytansine-based probes.

Development of [1,2]oxazoloisoindoles tubulin polymerization inhibitors: Further chemical modifications and potential therapeutic effects against lymphomas.

Lymphomas are among the ten most common cancers, and, although progress has been achieved in increasing survival, there is still an unmet need for more effective therapeutic approaches, including better options for patients with refractory tumors that initially respond but then relapse. The lack of effective alternative treatment options highlights the need to develop new therapeutic strategies capable of improving survival prospects for lymphoma patients. Herein, we describe the identification and exploration of the SAR of a series of [1,2]oxazolo[5,4-e]isoindoles as potent small molecules that bind to the colchicine site of tubulin and that have promise for the treatment of refractory lymphomas. Exploration of the chemical space of this class of compounds at the pyrrole moiety and at the [1,2]oxazole ring highlighted two compounds bearing a 3,5-dimethoxybenzyl and a 3,4,5-trimethoxybenzyl group as potent candidates and showed that structural modifications at the isoxazole moiety are generally not favorable for activity. The two best candidates showed efficacy against different lymphoma histotypes and displayed 88 and 80% inhibition of colchicine binding fitting well into the colchicine pocket, as demonstrated by X-ray crystallography T2R-TTL-complexes, docking and thermodynamic analysis of the tubulin-colchicine complex structure. These results were confirmed by transcriptome data, thus indicating [1,2]oxazolo[5,4-e]isoindoles are promising candidates as antitubulin agents for the treatment of refractory lymphomas.

Successful Treatment of Epstein-Barr Virus-Induced Necrotizing Retinitis with Intravitreous Ganciclovir, Foscarnet, and Methotrexate.

This is a report of an immunocompromised 49-year-old renal transplant patient with Epstein-Barr virus (EBV)-induced necrotizing retinitis (NR). The patient with NR underwent diagnostic vitrectomy. Polymerase chain reaction (PCR) testing of the vitreous fluid was positive for EBV (25,000 IU/mL) and negative for all other organisms. The patient was treated with intravitreous ganciclovir and foscarnet. After only mild clinical improvement in retinitis and an increased quantitative EBV PCR (69,000 IU/mL), intravitreous methotrexate was added to the aforementioned intravitreous antiviral injections. After eight rounds of ganciclovir/foscarnet and three injections of methotrexate, the NR resolved, the quantitative EBV PCR decreased to 29 IU/mL, and the patient's visual acuity improved. To our knowledge, this is only the second case report to demonstrate efficacy of intravitreous methotrexate in an immunocompromised patient with EBV-induced NR. Intravitreous methotrexate combined with ganciclovir and foscarnet may be an effective treatment strategy for patients with PCR-positive EBV-induced NR that does not respond to conventional antiviral therapy.

Maytansinol Derivatives: Side Reactions as a Chance for New Tubulin Binders.

Maytansinol is a valuable precursor for the preparation of maytansine derivatives (known as maytansinoids). Inspired by the intriguing structure of the macrocycle and the success in targeted cancer therapy of the derivatives, we explored the maytansinol acylation reaction. As a result, we were able to obtain a series of derivatives with novel modifications of the maytansine scaffold. We characterized these molecules by docking studies, by a comprehensive biochemical evaluation, and by determination of their crystal structures in complex with tubulin. The results shed further light on the intriguing chemical behavior of maytansinoids and confirm the relevance of this peculiar scaffold in the scenario of tubulin binders.

1,3-Benzodioxole-Modified Noscapine Analogues: Synthesis, Antiproliferative Activity, and Tubulin-Bound Structure.

Since the revelation of noscapine's weak anti-mitotic activity, extensive research has been conducted over the past two decades, with the goal of discovering noscapine derivatives with improved potency. To date, noscapine has been explored at the 1, 7, 6', and 9'-positions, though the 1,3-benzodioxole motif in the noscapine scaffold that remains unexplored. The present investigation describes the design, synthesis and pharmacological evaluation of noscapine analogues consisting of modifications to the 1,3-benzodioxole moiety. This includes expansion of the dioxolane ring and inclusion of metabolically robust deuterium and fluorine atoms. Favourable structural modifications were subsequently incorporated into multi-functionalised noscapine derivatives that also possessed modifications previously shown to promote anti-proliferative activity in the 1-, 6'- and 9'-positions. Our research efforts afforded the deuterated noscapine derivative 14 e and the dioxino-containing analogue 20 as potent cytotoxic agents with EC50 values of 1.50 and 0.73 µM, respectively, against breast cancer (MCF-7) cells. Compound 20 also exhibited EC50 values of <2 µM against melanoma, non-small cell lung carcinoma, and cancers of the brain, kidney and breast in an NCI screen. Furthermore, compounds 14 e and 20 inhibit tubulin polymerisation and are not vulnerable to the overexpression of resistance conferring P-gp efflux pumps in drug-resistant breast cancer cells (NCIADR/RES ). We also conducted X-ray crystallography studies that yielded the high-resolution structure of 14 e bound to tubulin. Our structural analysis revealed the key interactions between this noscapinoid and tubulin and will assist with the future design of noscapine derivatives with improved properties.

CASE SERIES OF HYPERBARIC OXYGEN THERAPY FOR CENTRAL RETINAL ARTERY OCCLUSION.

PURPOSE: To retrospectively report the outcomes of patients presenting to our facility with central retinal artery occlusion and receiving therapy with hyperbaric oxygen (HBO). METHODS: This was a retrospective, chart review at a single hospital center. Patients with diagnosed central retinal artery occlusion were treated with HBO twice daily for 5 days during their inpatient stay for a total of 10 HBO treatments. Main outcome was change from the documented presenting best-corrected visual acuity to discharge best-corrected visual acuity. Thirty-nine patients with central retinal artery occlusion were included in the analysis during a 30-month period. RESULTS: Twenty-eight of 39 patients (72%) had some improvement in acuity. There was a mean of 5.05 lines of improvement using a modified Snellen chart after completing their HBO treatment course. Patients treated within 12 hours of symptom onset showed the greatest improvement in their visual acuity (6.11 mean lines of improvement). Complications of therapy included middle ear barotrauma (10/39) and confinement anxiety (1/39) and did not interfere with the therapy regimen or hospital course. CONCLUSION: This retrospective case series supports the use of emergent HBO therapy as a viable treatment option for patients with central retinal artery occlusion. Hyperbaric oxygen therapy was safely administered and well tolerated.

Critical review: Typical and atypical optic neuritis.

Typical optic neuritis is an idiopathic demyelinating condition that is often associated with multiple sclerosis. This has been well characterized and has an excellent prognosis. Atypical optic neuritis can result from an inflammatory, infectious, or autoimmune disorder. Differentiating the two types of optic neuritis is paramount and may be challenging early on in the clinical course. This review describes the recent literature describing the pathophysiology, clinical presentation, neuroimaging, and management of these disorders.

Development and validation of a French questionnaire concerning patients' perspectives of the quality of palliative care: the QUALI-PALLI-Patient.

BACKGROUND: Indicators for the quality of palliative care are a priority of caregivers and managers to allow improvement of various care settings and their comparison. The involvement of patients and families is of paramount, although this is rarely achieved in practice. No validated assessment tools are available in French. Simple cultural adaption of existing questionnaires may be insufficient, due to the varying organization of care in different countries. The purpose of this study was to develop and validate a new instrument to measure the quality of palliative care and satisfaction from the patient point of view. METHODS: Results from a qualitative study were used by a multi-professional workgroup to construct an initial set of 42 items exploring six domains. A cross-sectional survey was conducted in seven hospitals, encompassing three care settings: two palliative care units, one palliative care hospital, and four standard medical units with a mobile palliative care team. All items were assessed for acceptability. We conducted exploratory structural analysis using Principal Component Analysis (PCA), and evaluated external validity by comparison against global rating of satisfaction and the MD Anderson Symptom Inventory (MDASI) questionnaire. RESULTS: A total of 214 patients completed the questionnaire. After removing 7 items from the response distribution, PCA identified eight interpretable domains from the 35 final items: availability of caregivers, serenity, quality of information, pain management, caregivers' listening skills, psychosocial and spiritual aspects, possibility to refuse (care or volunteers), and respect for the patient. Internal consistency was good or acceptable for all subscales (Cronbach's α 0.5-0.84), except the last one (0.15). Factorial structure was found globally maintained across subgroups defined by age, sex, Palliative Performance Scale (PPS ≥ 60%, 40-50% and ≤ 30%), and care settings. General satisfaction was inversely correlated with the 2 scores of the MDASI questionnaire: symptoms' severity and impact on life. Each subscale, except "possibility to refuse", correlated with general satisfaction. CONCLUSIONS: Quali-Palli-Pat appears to be a valid, reliable, and well-accepted French tool to explore the quality of care and the satisfaction of palliative care patients. It should be confirmed in a wider sample of care settings. TRIAL REGISTRATION: clinicaltrials.gov NCT02814682 , registration date 28.6.2016.

Practice Patterns After Acute Embolic Retinal Artery Occlusion.

PURPOSE: To compare stroke evaluations recommended by retina special-ists and neurologists for retinal artery occlusion (RAO). DESIGN: A cross-sectional survey. METHODS: An anonymous survey was emailed to members of the American Academy of Neurology Stroke Section listserv and vitreoretinal specialists registered with the American Academy of Ophthalmology. The survey was divided based on duration of symptoms before encounter: less than 12 hours, 24-48 hours, and more than 1 week. Institutional review board approval was obtained before data collection. RESULTS: Four hundred forty-eight surveys were completed (281 retinologists and 167 neurologists). Within 12 hours of RAO, most neurologists (75%) pursue a hospital-based evaluation, whereas the majority of retinologists (82%) pursue outpatient workup (P < 0.0001). Most neurologists (92%) and retinologists (98%) pursue outpatient stroke workup if symptoms have been present for more than 7 days. CONCLUSIONS: Neurologists pursue higher acuity care after RAO, whereas most retinologists order outpatient evaluations. Retina specialists should consider urgent stroke evaluation to mitigate stroke risk factors.

Masses in the membranes.

A 24-year-old woman with systemic lupus erythematosus presented with a 1-year history of painless vision loss in the right eye. Examination was notable for a bitemporal hemianopia. Brain imaging revealed multiple contrast enhancing dural masses, including one along the planum sphenoidale. She underwent excisional biopsy for a presumed diagnosis of multiple meningiomas. Five years later, she developed worsening vision in the left eye, hypesthesia in the V1 distribution, and oculomotor nerve palsy. Repeat imaging showed an enhancing mass in the cavernous sinus and orbital apex. Biopsy demonstrated a lymphoplasmacyte rich infiltrate in dense extracellular material. She was diagnosed with lupus-induced hypertrophic pachymeningitis and started on immunosuppressive therapy. On further worsening of symptoms, her initial biopsy was reexamined and revealed a kappa light chain restricted B-cell and plasmacyte population. This led to the final diagnosis of central nervous system extranodal marginal zone lymphoma.