Pancreatic neuroendocrine tumours in MEN1: the manifestation that kills, and the one the animal data points at
also called MEN1 pNET · duodenopancreatic NET · insulinoma MEN1 · gastrinoma MEN1
About half of people with a broken menin gene develop tumours in the hormone-making cells of the pancreas, and these are the MEN1 tumours most likely to be fatal. In children with MEN1 they appear as insulin-producing tumours in about one in eight.
The same thing, for a scientist
Enteropancreatic neuroendocrine tumours occurred in 49% of 258 systematically screened MEN1 carriers, with an age-related penetrance reaching about 60%, second only to parathyroid disease [E1]. In the GTE paediatric cohort, insulinoma was the presenting feature in 20 of 160 (12%), non-secreting pancreatic tumour in 14 (9%) and gastrinoma in 3 (2%); every insulinoma was operated before age 21 [E2]. Mechanistically this is the best-characterised MEN1 target tissue: beta-cell-specific Men1 ablation in mice gives hyperplastic islets by 2 months and insulinomas by 6 months with full penetrance [E3]. It is also the tissue in which the revumenib nonclinical package reports irreversible hyperplasia in rats at roughly twice the human exposure [E4], which makes this the one MEN1 manifestation with a direct, on-drug animal counterpart. **Correction, 2026-09-19:** the on-drug animal counterpart is two-sided and this entry previously gave only one side. Twelve weeks of a menin inhibitor at 70 mg/kg/day in diabetic mice produced increased beta-cell proliferation and mass with **lower** fasting glucose and improved glucose tolerance [E5], and acute inducible Men1 excision reverses established hyperglycaemia in three diabetic models [E6] - the same organ, the same target, graded as therapeutic. What distinguishes the revumenib finding is not that it is proliferation but that the label reports it as **irreversible**; that, and not the hyperplasia itself, is what should carry the weight here.
The human numbers
- Adult screened carriers: enteropancreatic tumours in 49%, maximum age-related penetrance ~60% 1.
- Paediatric/young-adult onset (GTE, n=160): insulinoma the first symptom in 12%, non-secreting pancreatic tumour in 9%, gastrinoma in 2%. All insulinomas, all adrenal tumours and the single thymic NET were operated before 21. One patient died before 21, of a thymic NET. Overall, lesions were malignant in four of the 160 2.
The GTE authors' summary line is the one to keep: MEN1 lesions occur frequently before 21 but mainly after 10 years of age, and rare aggressive tumours may develop at any age 2.
Why the pancreas is the tissue where the drug question bites hardest
Two independent lines converge on the islet.
Mouse genetics. Disrupting Men1 specifically in pancreatic beta cells produced hyperplastic islets as early as 2 months and insulinomas at 6 months, with full penetrance, through multistage progression including beta-cell dedifferentiation, angiogenesis and altered E-cadherin and beta-catenin, accompanied by disturbed blood insulin and glucose 3. Menin loss in a committed endocrine cell is therefore sufficient - no germline background needed - and the latency is months, not decades, once loss is complete and biallelic.
Drug nonclinical toxicology. The revumenib label records hyperplasia in multiple organs including the pancreas in rats at >=75 mg/kg/day for up to 13 weeks, with the pancreatic, testicular and mammary findings irreversible; that dose corresponds to approximately 2x the human AUC at the recommended dose 4. The label does not say whether the pancreatic hyperplasia was exocrine or islet, which is the single most consequential missing detail in this entire beat.
The honest reading is that these are two different perturbations - complete genetic ablation versus partial pharmacological occupancy - that happen to hit the same organ. Neither establishes that a child on revumenib for four cycles will get an islet lesion. Together they establish that the pancreas is where to look.
Correction, 2026-09-19: the pancreas is also where menin inhibition is pursued as a therapy
This entry cites the revumenib rat pancreatic hyperplasia as the animal counterpart of MEN1 pancreatic neuroendocrine disease. That is one legitimate reading, and the entry should also record the other: a nine-paper literature spanning 2007-2025 pursues menin inhibition in this same organ as a beta-cell regeneration strategy for diabetes, with the strongest single result being lower fasting glucose and higher beta-cell mass after 12 weeks of daily dosing 5, and reversal of established hyperglycaemia after acute Men1 excision in three diabetic models 6. See concept-menin-inhibition-is-an-active-therapeutic-hypothesis-in-diabetes.
Two things survive the correction intact and should be emphasised instead of the hyperplasia:
- The revumenib pancreatic finding is irreversible after drug withdrawal in the rat study; no beta-cell benefit study has an off-drug arm at all, so nothing in the benefit literature speaks to reversibility.
- Ma 2021 performed no pancreatic histopathology for neoplasia, so its silence on tumours is absence of measurement rather than a negative finding.
| organ | endocrine pancreas and duodenum |
|---|---|
| syndrome | multiple endocrine neoplasia type 1 |
penetrance by source
[
{
"cohort": "258 German MEN1 carriers",
"cumulative_frequency_pct": 49,
"max_age_related_penetrance_pct": 60,
"source": "E1"
},
{
"cohort": "160 GTE patients before age 21",
"insulinoma_first_symptom_pct": 12,
"nonsecreting_pct": 9,
"gastrinoma_pct": 2,
"source": "E2"
}
]mouse latency
{
"model": "beta-cell-specific Men1 ablation",
"hyperplasia_months": 2,
"insulinoma_months": 6,
"penetrance": "full",
"source": "E3"
}drug nonclinical counterpart
{
"species": "rat",
"finding": "pancreatic hyperplasia, irreversible",
"duration_weeks": 13,
"exposure_multiple_of_human_auc": 2,
"source": "E4"
}screening tests
[ "fasting glucose and insulin", "fasting gastrin", "chromogranin A", "pancreatic MRI or endoscopic ultrasound" ]
- The counter-argument at full strength: beta-cell Men1 ablation is complete and permanent from development; a menin inhibitor occupies a pocket partially and reversibly for a median of 2.5 months on the revumenib label. Full penetrance in the mouse says nothing about fractional, time-limited occupancy.
- MEN1-deficient pNET formation requires activated beta-catenin signalling as a further step, and there is no evidence a drug exposure supplies it.
- Irreversible rodent findings on this exact drug (lens opacity, nerve fibre degeneration) did not translate into comparable human harm, which is evidence that the rat hyperplasia may not either.
- Was the pancreatic hyperplasia in the revumenib rat study islet or exocrine? This single histological detail decides whether the nonclinical package contains a MEN1-axis signal or an unrelated one, and it is answerable from the FDA pharmacology review.
- Do children on menin inhibitors show any drift in fasting glucose, insulin or C-peptide? None of the three registered trials collects these, and they are add-on assays on blood already being drawn.
- Does partial, reversible menin-pocket occupancy engage beta-catenin signalling in islets at all? If it does not, the Jiang result argues the islet path to tumour is not opened by a drug exposure.
- Is the rat pancreatic hyperplasia on the revumenib label islet or exocrine, and beta-cell or alpha-cell? The label does not say, and the answer decides whether it is the MEN1 phenotype or the diabetes-therapeutic one.
- E1strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
Enteropancreatic tumours developed in 49% of 258 systematically screened MEN1 germline mutation carriers, with maximum age-related penetrance of approximately 60%, second in frequency only to parathyroid disease.
Age-related penetrance of endocrine tumours in multiple endocrine neoplasia type 1 (MEN1): a multicentre study of 258 gene carriers. · Machens A, Schaaf L, Karges W, Frank-Raue K, Bartsch DK, Rothmund M, Schneyer U, Goretzki P, Raue F, Dralle H · Clin Endocrinol (Oxf) 67:613-22 2007What this evidence cannot show
Read as abstract. Referral-centre carriers, mean age 43; the abstract aggregates enteropancreatic tumours rather than separating insulinoma, gastrinoma and non-functioning pNET, so the per-tumour penetrance cannot be recovered from it.
Evidence that argues against this (1)
- Forty-nine per cent enteropancreatic penetrance comes from SYSTEMATIC SCREENING of known carriers, which detects small and asymptomatic lesions a clinical cohort would never record. The figure is a screening yield, not a burden of disease, and screened penetrance runs well above clinically apparent penetrance. Clinical Endocrinology 2007
- E2strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
In 160 GTE cohort patients with MEN1 disease before 21 years, the first symptom was insulinoma in 20 (12%), non-secreting pancreatic tumour in 14 (9%) and gastrinoma in 3 (2%); all insulinomas were operated before age 21, one patient died before 21 from a thymic neuroendocrine tumour, and lesions were malignant in four patients overall.
MEN1 disease occurring before 21 years old: a 160-patient cohort study from the Groupe d etude des Tumeurs Endocrines · Goudet P, Dalac A, Le Bras M, Cardot-Bauters C, Niccoli P, Levy-Bohbot N, et al., Delemer B · J Clin Endocrinol Metab 100:1568-77 2015What this evidence cannot show
Read as abstract. Early-onset-selected cohort, so these proportions describe presentation pattern rather than penetrance. The abstract does not give age at insulinoma diagnosis separately from age at first MEN1 symptom.
Evidence that argues against this (1)
- The paediatric GTE series is ascertained through MEN1 families, so the proportions describe which tumour declares itself first in a screened carrier. They cannot be transferred to a non-carrier population, and the entry's relevance to menin-inhibitor liability depends entirely on that transfer. Journal of Clinical Endocrinology & Metabolism 2015
- E3strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
Mice with Men1 disrupted specifically in pancreatic beta cells developed hyperplastic islets as early as 2 months of age and insulinomas at 6 months, with full penetrance, showing multistage progression including beta-cell dedifferentiation and angiogenesis, and disturbed blood insulin and glucose.
Pancreatic beta-cell-specific ablation of the multiple endocrine neoplasia type 1 (MEN1) gene causes full penetrance of insulinoma development in mice · Bertolino P, Tong WM, Herrera PL, Casse H, Zhang CX, Wang ZQ · Cancer Res 63:4836-41 2003What this evidence cannot show
Read as abstract. Complete biallelic Men1 ablation in a lineage from development onward is a far more severe perturbation than partial, reversible pocket occupancy in a treated child, and the mouse lifespan compresses all latencies. The abstract does not report an untreated-control tumour rate because none is expected.
Evidence that argues against this (1)
- Menin loss is not sufficient on its own to make an aggressive tumour: in MEN1-deficient pNETs the tumorigenic phenotype runs through activated beta-catenin signalling, and conditional knockout of beta-catenin suppresses tumorigenesis and prolongs survival in Men1-deficient mice, while blockade of beta-catenin had no adverse effect on physiological beta-cell function. So the path from menin loss to islet tumour has at least one further required node, which a months-long reversible drug exposure would not obviously engage. Jiang X et al. 2014
- E4established confidence 5 of 5: Multiple independent lines of evidence; treated as settled in the field.database
The revumenib prescribing information reports that hyperplasia was observed in multiple organs including the testes, mammary gland, uterus, pancreas and kidney in rats treated at 75 mg/kg/day or above for up to 13 weeks, that the findings were irreversible in the testes, mammary gland and pancreas, and that exposures at 75 mg/kg/day are approximately 2 times the human exposure at the recommended dose.
REVUFORJ (revumenib) tablets, for oral use - US full prescribing information (NDA 218944) · Syndax Pharmaceuticals / US FDA · DailyMed / Drugs@FDA (NDA 218944) 2025What this evidence cannot show
Read verbatim from the DailyMed full prescribing information, section 13.2, on 2026-09-18. The label does not state whether the pancreatic hyperplasia was islet or exocrine, does not give incidence, and does not state the recovery period length for the rat study (a 13-week recovery is stated only for the dog study). Rat-to-human extrapolation of proliferative findings is weak, and rats are prone to spontaneous proliferative lesions in several of these organs.
Evidence that argues against this (1)
- The same label section records findings that are clearly not MEN1-axis effects and that did not translate proportionately into the clinic - lens opacities in rats that progressed and did not reverse, and nerve fibre degeneration in dogs that did not reverse - while the corresponding human rates were cataract listed only among reactions under 20% and peripheral neuropathy in 3.2% of patients in the pivotal publication, all below grade 2. That is a direct demonstration that irreversible rodent and dog findings on this drug can overstate human risk. Issa GC et al. 2024
- E5moderate confidence 3 of 5: One strong study, or several smaller consistent ones.paper
Twelve weeks of a menin inhibitor at 70 mg/kg/day increased beta-cell proliferation and mass and lowered fasting glucose in diabetic mice, with no pancreatic histopathology for neoplasia performed.
Menin-regulated Pbk controls high fat diet-induced compensatory beta cell proliferation. · Ma J, Xing B, Cao Y, He X, et al. · EMBO Molecular Medicine 2021What this evidence cannot show
Tool compound MI-463, n=4-5, adult mice, no off-drug follow-up, no tumour assessment.
Evidence that argues against this (1)
- The revumenib label reports the rat pancreatic hyperplasia as irreversible at ~2x human AUC. Syndax Pharmaceuticals et al. 2026
- E6strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
Acute inducible Men1 excision reverses established hyperglycaemia in streptozotocin, db/db and high-fat-diet diabetic mice by expanding beta-cell mass.
Reversal of preexisting hyperglycemia in diabetic mice by acute deletion of the Men1 gene. · Yang Y, Gurung B, Wu T, Wang H, Stoffers DA, Hua X · Proceedings of the National Academy of Sciences USA 2010What this evidence cannot show
Genetic excision; mouse; no tumour follow-up.
Evidence that argues against this (1)
- Conditional beta-cell Men1 deletion followed to old age produces glucagon-expressing tumours and loss of beta-cell identity. Li F et al. 2015
beta-cell Men1 ablation gives hyperplastic islets at 2 months and insulinoma at 6 months with full penetrance
the rat nonclinical package reports irreversible pancreatic hyperplasia at about 2x the human AUC
- supports →The same pocket suppresses JUND: menin inhibition's unmeasured endocrine liability in infants
the one MEN1 manifestation with a direct on-drug animal counterpart in the same organ
hyperplasia is the first phenotype of menin loss in endocrine tissue; the pancreas is the one organ of five that matches
- ← related toHow long does menin have to be gone? Two months in a mouse islet, a decade or more in a human carrier
the mouse anchor: hyperplastic islets at 2 months, insulinoma at 6, with complete biallelic loss
- ← co-occurs withSwitching menin off reverses diabetes that is already there - in three different diabetic mouse models
Same tissue, same gene, opposite sign at different exposure durations: reversal of hyperglycaemia at weeks, insulinoma at months
supplies the DAXX/ATRX co-mutation and the ALT consequence, neither of which that entry contains