The review’s central message is that PitNETs are not one disease but a family of diseases. Modern classification, reflected in the World Health Organization’s 2017 and 2022 frameworks, now relies on transcription factors and hormone markers to sort tumors into lactotroph, somatotroph, corticotroph, thyrotroph, and gonadotroph lineages, each with distinct behavior and treatment sensitivity. Beneath that clinical taxonomy lies a layer of recurrent molecular alterations. Activating mutations in GNAS, the gene encoding the Gs alpha subunit, drive cyclic AMP signaling in many somatotroph tumors, while mutations in USP8, a deubiquitinase, destabilize feedback control of the glucocorticoid receptor and characterize many corticotroph tumors. Beyond these driver mutations, broader signaling networks are repeatedly found dysregulated, including the PI3K/AKT/mTOR axis, the MAPK cascade, and pathways governing cell cycle progression, angiogenesis, and metabolism. Spatial transcriptomics studies of aggressive, treatment-resistant lactotroph tumors have revealed coordinated PI3K-AKT and metabolic alterations, while longitudinal multi-omics comparisons of primary and recurrent tumors from the same patients suggest that genomic stability can coexist with shifting transcriptomic profiles, hinting that epigenetic and metabolic plasticity, rather than new mutations, may underlie recurrence.

For prolactin-secreting tumors, the therapeutic mainstay remains dopamine agonists such as cabergoline, which activate dopamine receptor type 2 on lactotroph cells and suppress both prolactin secretion and cell proliferation. Yet a substantial minority of patients are resistant, and the molecular basis of that resistance is now coming into focus. Studies summarized in the review implicate reduced receptor expression, altered downstream signal transduction involving cAMP/PKA-mediated filamin A phosphorylation, and, strikingly, androgen receptor signaling that regulates intracellular reactive oxygen species in resistant prolactinomas. One promising experimental direction is the development of beta-arrestin 2-biased dopamine receptor agonists, which in preclinical work showed greater efficacy than cabergoline at reducing proliferation in prolactin-secreting cells. Such biased agonism illustrates a broader principle in modern endocrine oncology: rather than simply switching a receptor on or off, drugs can be engineered to favor the specific intracellular signaling branches that produce therapeutic benefit while avoiding those that cause harm.

For growth hormone-secreting tumors, somatostatin receptor ligands exploit the fact that many somatotroph tumors abundantly express somatostatin receptor subtypes 2 and 5. Analogues such as octreotide and lanreotide bind these receptors to suppress growth hormone release and slow tumor growth, while the multi-ligand analogue pasireotide engages additional receptor subtypes, at the cost of greater metabolic side effects. The review emphasizes that receptor expression profiles, assessed by pathologists on tumor tissue, can predict response, and that epigenetic silencing of receptor genes may explain some treatment failures, raising the possibility of epigenetic drugs such as guadecitabine to restore receptor expression and unlock peptide receptor radiotherapy. A novel somatostatin receptor ligand developed for ACTH- and GH-secreting tumors, structural insights into nonpeptide antagonists of receptor subtype 5, and chimeric molecules that combine somatostatin and dopamine receptor activity all point toward a next generation of receptor-targeted pharmacology. For patients whose tumors evade these approaches, the growth hormone receptor antagonist pegvisomant blocks growth hormone signaling at its receptor, and temozolomide, an oral alkylating chemotherapy borrowed from neuro-oncology, has become the standard cytotoxic option for aggressive and malignant PitNETs.

Where established drugs fail, the review turns to molecularly targeted strategies with varying levels of evidence. mTOR pathway inhibition is supported by immunohistochemical demonstration of pathway activation in functional PitNETs and by preclinical studies, though clinical data remain limited. Anti-angiogenic therapy with bevacizumab has been explored both as a treatment and, intriguingly, as a fluorescent surgical probe: the DEPARTURE feasibility trial tested bevacizumab-800CW to help surgeons visualize tumor tissue during endoscopic transsphenoidal surgery. Immune checkpoint inhibition, transformative in many cancers, is still at the case-report and small-series stage in PitNETs, with the review carefully noting that evidence for its use in aggressive and metastatic cases remains preliminary. Other emerging ideas include glucocorticoid receptor antagonism with relacorilant, which upregulates somatostatin receptor subtype 2 expression in ACTH-producing tumors and could sensitize them to somatostatin analogues, BMP signaling agonists that trigger autophagic death of corticotroph tumor cells through a BMP4/SMAD-dependent pathway, growth hormone-releasing hormone antagonists that hamper oncogenic signaling, tamoxifen explored in a proof-of-concept study for residual nonfunctioning PitNETs, and even ruthenium-based photodynamic therapy targeting PI3K/AKT/p53 signaling in nonfunctioning tumors in preclinical models.

Perhaps the most distinctive contribution of the review is its treatment of drug delivery as a discipline in its own right. The pituitary sits within the sella turcica, behind the blood-brain barrier and wrapped in a dense capillary network, making selective drug delivery genuinely difficult. The authors evaluate intranasal delivery routes that could bypass systemic exposure, nanoparticle-based systems including lipid nanoparticles, liposomal carriers that improve drug solubility and reduce toxicity, receptor-targeted platforms that home in on tumor-specific surface molecules, and sustained-release formulations that smooth out the pharmacokinetic peaks and troughs of chronic therapy. Crucially, they insist on a distinction that is often blurred in the literature: some delivery technologies, such as long-acting injectable somatostatin analogue formulations, are clinically established, while others, including many nanoparticle and receptor-targeted approaches, remain experimental or are supported mainly by evidence extrapolated from other therapeutic areas such as breast cancer and general neuroendocrine tumor care.

This sober calibration matters because the translational pipeline from bench to bedside in pituitary disease is constrained by rarity. PitNETs affect a meaningful fraction of the population, with many incidentally discovered, but aggressive and drug-resistant forms are uncommon, making large randomized trials difficult to mount. The review therefore leans on clinical trial evidence from related neuroendocrine tumors, such as radiolabeled somatostatin receptor therapies using lutetium-177 and emerging terbium-161 combinations, gallium-68 somatostatin receptor antagonist PET imaging in hundreds of patients, and consensus statements from the Pituitary Society standardizing the management of prolactinomas. Radiopharmaceutical theranostics, in which the same receptor-targeted molecule is used first to image and then to irradiate a tumor, exemplify how delivery and therapy can be fused into a single platform, and the agonist-versus-antagonist debate in that field is directly relevant to pituitary tumors that express somatostatin receptors.

The biological heterogeneity that makes PitNETs challenging also makes them a compelling testbed for precision endocrinology. Transcription factor-based classification across successive WHO editions, analyzed in a series of 921 cases, is converging with multi-omics profiling to identify which tumors will behave aggressively and which molecular vulnerabilities they carry. MicroRNAs such as miR-7, which regulate the hypothalamic-pituitary axis, epigenetic dysregulation of somatostatin receptors, and hedgehog signaling demonstrated in pituitary adenoma organoids all suggest layers of regulation that could be exploited pharmacologically. Organoid models in particular offer a way to test receptor expression and drug responses in tissue that mirrors an individual patient’s tumor, potentially enabling the kind of personalized receptor profiling that already guides somatostatin analogue selection. Meanwhile, research into aging-related pituitary changes and the crosstalk between tumor cells, neurons, and immune cells in the tumor microenvironment is expanding the list of possible intervention points.

What emerges from the Shadab and Hailat review is a field in transition. The established pharmacological arsenal, dopamine agonists, somatostatin receptor ligands, pegvisomant, and temozolomide, controls the majority of hormone-secreting PitNETs, but resistance and aggression in a stubborn minority continue to drive morbidity. The molecular map of those failures is now detailed enough to suggest concrete targets, from biased dopamine receptor agonists and mTOR inhibitors to epigenetic priming of receptor expression, and the delivery toolbox, from lipid nanoparticles to intranasal and sustained-release platforms, is maturing in parallel. The authors’ insistence on separating clinical reality from experimental promise is a useful discipline for readers navigating a literature full of preclinical enthusiasm. For patients with refractory tumors, the near future likely holds better molecular stratification, receptor-guided combination therapy, and radiopharmaceutical options borrowed from the broader neuroendocrine tumor community, while truly pituitary-specific targeted delivery remains a goal that will require the kind of systematic synthesis this review provides.

Subject of Research: Molecular pathophysiology and targeted drug delivery strategies for pituitary neuroendocrine tumors

Article Title: Pituitary adenomas (PitNETs): molecular pathophysiology, targeted drug delivery strategies and clinical therapeutic outcomes

Article References: Shadab, A., & Hailat, M. (2026). Pituitary adenomas (PitNETs): molecular pathophysiology, targeted drug delivery strategies and clinical therapeutic outcomes. Molecular Biology Reports, 53(1), Article 1714. https://doi.org/10.1007/s11033-026-12915-3

Image Credits: AI Generated

DOI: 10.1007/s11033-026-12915-3

Keywords: pituitary neuroendocrine tumors, PitNETs, dopamine agonists, somatostatin receptor ligands, PI3K/AKT/mTOR, temozolomide, drug delivery, nanoparticles, molecular pathophysiology, targeted therapy, neuroendocrine tumors, endocrinology

The study drew on a large national cohort assembled from the Finnish Parkinson’s Association, an organization with roughly 7,500 members, of whom 5,373 were registered as Parkinson’s patients. From this registry, the researchers randomly selected 1,500 individuals and mailed a structured sleep questionnaire to 1,447 eligible participants between 2010 and 2011. Every included patient had a Parkinson’s diagnosis confirmed by a neurologist in accordance with national clinical guidelines consistent with the Gelb diagnostic criteria. The questionnaire incorporated validated sleep items from the Basic Nordic Sleep Questionnaire, a well-established instrument for quantifying subjective sleep complaints. A follow-up questionnaire was sent in 2014 to 2015, and after reminders and telephone contact, 183 participants provided complete data at both time points, forming the analytical cohort for the longitudinal comparison.

The researchers measured an unusually broad set of sleep domains at both time points. Daytime sleepiness was assessed with the Epworth Sleepiness Scale, restless legs syndrome with the international four-item diagnostic criteria, and REM sleep behavior disorder symptoms with the REM Sleep Behavior Disorder Screening Questionnaire, on which a score of six or higher suggests the disorder. Sleep apnea risk was screened with the STOP questionnaire, insomnia symptoms were captured through difficulty initiating sleep, nocturnal awakenings, early morning awakenings, and non-restorative sleep, and circadian timing was estimated from midsleep, the midpoint between sleep onset and wake time. The team also recorded medication use, converting self-reported drugs into levodopa equivalent doses, and screened depressive symptoms with Rimon’s Brief Depression Scale, an instrument deliberately designed to exclude insomnia items so that sleep complaints would not inflate depression scores.

Over the five-year interval, mean disease duration in the cohort rose from 5.5 to 9.7 years, mean levodopa equivalent dose increased from 607.8 to 732.6 milligrams, and the proportion of sedentary participants nearly doubled from 9.0 to 18.0 percent. Against this backdrop of advancing disease, the sleep data told a nuanced story. Total sleep time edged up only trivially, from 7.0 to 7.2 hours, a change that was not statistically significant. Individual insomnia symptoms, including trouble falling asleep, frequent night awakenings, early morning awakening, and unrefreshing sleep, showed no significant deterioration, and a composite measure capturing any insomnia symptom or regular use of sleep medication remained flat. Daytime fatigue and hallucinations were likewise stable, a finding that contrasts with several earlier reports describing insomnia as a progressively worsening complaint in Parkinson’s disease.

In sharp contrast, the symptoms tied to REM sleep pathology advanced markedly. The proportion of participants who talked in their sleep at least once a week nearly doubled, rising from 17.4 to 30.4 percent. Weekly nightmares increased from 14.8 to 24.6 percent. The mean REM Sleep Behavior Disorder Screening Questionnaire score climbed from 4.4 to 5.3 points, and the share of participants crossing the screening threshold of six or more rose from 28.9 to 39.9 percent. REM sleep behavior disorder, in which patients act out their dreams because the normal muscle paralysis of REM sleep fails, is recognized as a core prodromal feature of synucleinopathies, the family of neurodegenerative diseases that includes Parkinson’s, and it is strongly linked to later cognitive decline and a more aggressive disease course. The authors argue that the longitudinal rise in these symptoms reflects active progression of REM sleep pathology rather than an incidental annoyance.

Daytime sleepiness also worsened in clinically meaningful ways. The proportion of participants with an Epworth Sleepiness Scale score above 10, the conventional cutoff for excessive sleepiness, increased from 30.6 to 38.8 percent, while severe sleepiness, defined as a score above 15, rose from 8.9 to 14.8 percent. Daily napping grew from 21.4 to 31.7 percent of the cohort, likely mirroring the rising sleepiness. Prevalence of restless legs syndrome climbed from 21.0 to 31.2 percent, an increase the authors note is broadly consistent with cross-sectional studies showing elevated restless legs frequency in more advanced Parkinson’s disease. Because restless legs syndrome shares dopaminergic pathways with Parkinson’s itself, the rise alongside increasing levodopa doses could reflect inadequate treatment or, importantly, augmentation, a paradoxical worsening of symptoms caused by long-term dopaminergic therapy itself.

To understand what drove the worsening sleepiness, the researchers built multivariate logistic regression models with excessive daytime sleepiness as the outcome. Three factors emerged as independent predictors: higher depression scores, use of dopamine agonists, and high risk of sleep apnea on the STOP questionnaire. Dopamine agonist use carried an odds ratio of 3.92, meaning users faced nearly four times the odds of excessive sleepiness compared with non-users after adjustment. Notably, neither levodopa nor MAO inhibitor use was associated with sleepiness, and age, total sleep time, and REM behavior disorder screening score were not independently predictive. The authors emphasize that this pattern highlights the need to investigate secondary, potentially treatable causes, such as undiagnosed sleep apnea or depression, before attributing sleepiness solely to disease progression.

The study has important strengths and candidly acknowledged limitations. Its prospective design with a five-year interval and consistent use of a validated questionnaire at both time points allow genuine longitudinal inference across multiple sleep domains simultaneously, something most prior studies, which typically examined single symptoms in cross-sectional or short-term designs, could not provide. However, the follow-up sample of 183 is small relative to the baseline cohort of 611, and the analysis was restricted to participants with complete data at both points. Those who completed follow-up were younger, had shorter disease duration, higher body mass index, and better quality of life than those excluded, indicating a healthy-survivor effect that likely makes the reported changes conservative underestimates of true progression. The questionnaire-based approach also means that REM sleep behavior disorder and sleep apnea were identified through surrogate markers rather than video-polysomnography, the gold standard, and Parkinson’s diagnoses were self-reported as neurologist-confirmed without record re-verification.

Despite these caveats, the selective pattern of progression carries a clear clinical message. Sleep in Parkinson’s disease is not a single monolithic complaint that simply deepens over time; it is a collection of distinct disorders evolving on different trajectories, some driven by neurodegeneration, some by medication, and some by comorbid conditions. The stability of insomnia and total sleep time suggests that these features may reflect aging and individual vulnerability more than disease progression, whereas the rise in REM-related behaviors, sleep talking, and nightmares tracks the underlying neurodegenerative process and, as the team’s earlier work in this same cohort showed, is associated with increased mortality. The authors conclude that multi-domain sleep assessment should be routine in Parkinson’s care, and that sleep talking and REM behavior disorder screening scores deserve attention not merely as symptoms to soothe but as markers of disease progression with genuine prognostic weight. For patients and clinicians alike, the message is that worsening sleep deserves careful, domain-specific evaluation rather than a one-size-fits-all response.

Subject of Research: Longitudinal changes in sleep characteristics and sleep disorders over five years in Parkinson's disease

Article Title: Changes in sleep characteristics in Parkinson’s disease: a prospective 5-year follow-up study

Article References: Partinen, E., Ylikoski, A., Hublin, C., & Partinen, M. (2026). Changes in sleep characteristics in Parkinson’s disease: a prospective 5-year follow-up study. Journal of Clinical Sleep Medicine, 22(1), Article 166. https://doi.org/10.1007/s44470-026-00169-6

Image Credits: AI Generated

DOI: 10.1007/s44470-026-00169-6

Keywords: Parkinson's disease, sleep disorders, excessive daytime sleepiness, REM sleep behavior disorder, sleep talking, nightmares, restless legs syndrome, insomnia, dopamine agonists, sleep apnea, prospective cohort study, daytime napping