How long does menin have to be gone? Two months in a mouse islet, a decade or more in a human carrier
also called MEN1 latency · time to tumour after menin loss · menin loss kinetics
In mice whose insulin-making cells lose menin completely, the cells start over-growing within two months and become tumours by six. In people who inherit one faulty copy, it usually takes more than ten years for anything to appear.
The same thing, for a scientist
The latency from menin loss to endocrine neoplasia depends almost entirely on how complete the loss is. **Complete, cell-autonomous, biallelic loss** in mouse beta cells produces hyperplastic islets by 2 months and insulinomas by 6 months with full penetrance [E1]. **Germline monoallelic loss** in humans - half the gene dose in every cell from conception - produces 7% disease penetrance at age 10 and 52% at 20 [E2], with the earliest tumour manifestation across all MEN1 tumour types reported at 9 years [E3]. These are the two anchors that bracket the question, and they are two orders of magnitude apart. The drug sits in neither bracket: a menin inhibitor produces partial, reversible, non-genetic loss of one menin function for a median of 2.5 months. **Correction, 2026-09-19:** two further anchors exist and the bracket as drawn is therefore incomplete, in the direction that makes short exposures look worse than the evidence supports. (i) **Physiological** menin down-regulation of roughly 50% happens routinely in the healthy beta cell, driven by pregnancy/prolactin and by glucose, and its consequence is adaptive proliferation, not neoplasia [E7]. (ii) **Acute inducible biallelic Men1 excision** - a deeper exposure than the drug - reverses established hyperglycaemia in three diabetic mouse models at the week-to-month timescale, and a menin inhibitor given for 12 weeks in vivo produced increased beta-cell mass with improved glucose tolerance [E8][E9]. The early part of the beta-cell menin-loss curve is therefore **beneficial**, and only its late part is neoplastic. See `concept-four-exposure-classes-of-menin-loss-are-not-interchangeable`.
The two anchors1 deeper
| Perturbation | Completeness | Duration to first phenotype | Source |
|---|---|---|---|
| Beta-cell-specific Men1 ablation, mouse | complete, biallelic, permanent, cell-autonomous | hyperplastic islets at 2 months; insulinoma at 6 months; full penetrance | 1 |
| MEN1 germline mutation, human | monoallelic, permanent, every cell from conception | 7% affected at age 10; 52% at 20; earliest manifestation reported at 9 years | 23 |
| Revumenib exposure, human | partial, one function, reversible | median 2.5 months (range <1 to 40); 10% beyond 6 months | 4 |
One crude allometric note, flagged as arithmetic rather than biology: 2 months is roughly 6-7% of a laboratory mouse's lifespan, which on a naive lifespan scaling maps to about 5 years of human life. That is the same order as the human germline anchor's earliest events, which is mildly reassuring about the internal consistency of the two systems. It is not a quantitative prediction and should not be used as one.
What the mouse actually shows, and what it cannot
The beta-cell model is the cleanest available demonstration that menin loss in a committed endocrine cell is sufficient for neoplasia with no germline background and no second organ involved: hyperplastic islets at 2 months progressing through beta-cell dedifferentiation, angiogenesis and altered E-cadherin and beta-catenin, to insulinoma at 6 months, with blood insulin and glucose disturbance mimicking human MEN1 1.
What it cannot show is a threshold. The model has no partial-loss arm and no drug arm. Nobody has published a conditional Men1 system in which menin is removed for a defined window and then restored, which is the experiment that would directly bound the drug question. Its absence is the single largest gap in this beat, and it is a tractable mouse experiment.
A constraint that does emerge from the same tissue: MEN1-deficient pNET formation runs through activated beta-catenin signalling, and conditionally deleting beta-catenin suppresses tumorigenesis and prolongs survival in Men1-deficient mice, while beta-catenin blockade does not harm normal beta-cell function 5. So menin loss alone is not the whole path; at least one further node must be engaged.
Where the paediatric human data bite
The reassuring reading of the human anchor - 93% of carriers disease-free at 10 - has an important qualification. In the GTE cohort of 160 patients whose MEN1 manifested before 21, first symptoms occurred before 10 years in 22 patients (14%) and before 5 years in 5 (3%) 6. Those are proportions within an early-onset cohort, not penetrance, but they establish existence: MEN1 disease does occur in children under 5 with only germline haploinsufficiency behind it.
The cohort's own summary is the balanced one: MEN1 lesions occur frequently before 21 but mainly after 10 years of age, and rare aggressive tumours may develop at any age 6.
Correction, 2026-09-19: there are four anchors, not two
The entry brackets the latency question with complete beta-cell ablation (hyperplasia at 2 months, insulinoma at 6) and human germline heterozygosity (7% penetrance at 10 years). Two more anchors exist and both sit at the short end:
| Exposure | Duration | Outcome |
|---|---|---|
| Physiological ~50% menin fall (pregnancy, hyperglycaemia) | days-weeks | Adaptive beta-cell proliferation; blocking it causes gestational diabetes 7 |
| Acute inducible biallelic Men1 excision | weeks-months | Reverses established hyperglycaemia in streptozotocin, db/db and high-fat-diet mice 8 |
| Menin inhibitor, 70 mg/kg/day | 12 weeks | Beta-cell mass up, fasting glucose down, glucose tolerance improved 9 |
| Complete beta-cell Men1 ablation | 2-6 months | Hyperplastic islets, then insulinoma (as the entry states) |
| Germline monoallelic loss | decades | MEN1 penetrance curve (as the entry states) |
The correction is not that the entry is wrong about the neoplastic end. It is that the curve has a beneficial early phase that the entry omits, and omitting it makes a short drug exposure appear to sit at an unmeasured point on a monotonic path to tumour, when the measured points nearest to it in duration are benign or beneficial.
| required further node | activated beta-catenin signalling for Men1-deficient pNET formation (E5) |
|---|---|
| missing experiment | a conditional Men1 system with menin removed for a defined window and then restored; no such study was located |
| allometric note | 2 mouse months is roughly 6-7% of murine lifespan, naively scaling to about 5 human years; this is arithmetic, not a prediction |
anchors
[
{
"system": "mouse beta-cell-specific Men1 ablation",
"completeness": "complete biallelic, permanent",
"hyperplasia_months": 2,
"tumour_months": 6,
"penetrance": "full",
"source": "E1"
},
{
"system": "human MEN1 germline carrier",
"completeness": "monoallelic, permanent, from conception",
"penetrance_age_10_pct": 7,
"penetrance_age_20_pct": 52,
"earliest_manifestation_years": 9,
"source": "E2, E3"
},
{
"system": "revumenib-treated human",
"completeness": "partial, one function, reversible",
"median_exposure_months": 2.5,
"max_exposure_months": 40,
"pct_beyond_6_months": 10,
"source": "E4"
}
]- The two anchors bracket the drug exposure but neither contains it, and interpolating between a complete genetic ablation and a germline haploinsufficiency to predict what partial reversible occupancy does is not a defensible inference. This entry should be read as a statement of what is not known.
- The human anchor is strongly reassuring: permanent half-dose menin from conception leaves 93% of carriers disease-free at 10.
- The mouse anchor is strongly cautionary but at the wrong completeness, and it has no partial or reversible arm - which is precisely why the missing restoration experiment matters more than any further human observation.
- Has anyone built a reversible Men1 conditional system - menin off for 1, 3 or 6 months and then restored - and measured islet or parathyroid outcome? This is the single experiment that would bound the drug question and no published example was located.
- What is the minimum duration of complete Men1 loss that produces an irreversible islet lesion in mouse? The 2-month hyperplasia figure is the earliest observation, not a threshold.
- Is hyperplasia at 2 months reversible on menin restoration, or already committed? The distinction is the whole question for a child who stops the drug.
- Does any human data exist on endocrine outcome in patients who took a menin inhibitor and were cured? Long-term survivors of the phase 1 cohort are now several years out.
- Where on the duration axis does the beta-cell response cross from adaptive to neoplastic? The measured points at 12 weeks and at 6 months point in opposite directions and nothing has been measured between them.
- E1strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
Mice with Men1 disrupted specifically in pancreatic beta cells began to develop hyperplastic islets as early as 2 months of age and insulinomas at 6 months, with islet lesions showing multistage tumour progression including beta-cell dedifferentiation, angiogenesis and altered expression of E-cadherin and beta-catenin, and with disturbance of blood insulin and glucose correlating with tumour development.
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 ablation from development in a single lineage; no partial-loss arm, no drug arm, no restoration arm. Mouse lifespan compresses all latencies relative to human. The abstract does not give the number of animals or the proportion hyperplastic at 2 months.
Evidence that argues against this (1)
- The model and the drug differ on every axis that sets risk. Beta-cell-specific Men1 ablation is CONSTITUTIVE, BIALLELIC and present from development, in an animal whose islets never experienced normal menin. A treated child has two intact MEN1 alleles, full menin protein, and reversible occupancy of one pocket on it for a defined period. The mouse establishes what permanent total loss does to an islet; it does not calibrate what partial temporary inhibition does. Cancer Research 2003
- E2established confidence 5 of 5: Multiple independent lines of evidence; treated as settled in the field.paper
Age-related penetrance of MEN1 in 201 identified germline mutation carriers from 63 kindreds was 7%, 52%, 87%, 98%, 99% and 100% at 10, 20, 30, 40, 50 and 60 years of age.
Characterization of mutations in patients with multiple endocrine neoplasia type 1 · Bassett JH, Forbes SA, Pannett AA, Lloyd SE, Christie PT, Wooding C, Harding B, Besser GM, Edwards CR, Monson JP, Sampson J, Wass JA, Wheeler MH, Thakker RV · Am J Hum Genet 62:232-44 1998What this evidence cannot show
Read as abstract. Family-based ascertainment biases penetrance upward; detection reflects 1990s screening intensity so true biological onset precedes ascertained onset by an unknown interval.
Evidence that argues against this (1)
- A penetrance curve measures the cumulative probability of a SECOND somatic hit in a tissue that has carried monoallelic loss since conception. Pharmacological inhibition supplies no first hit, removes no allele, and stops. Reading 52% at 20 years as a hazard for a treated patient imports a mutational clock that drug exposure does not start. American Journal of Human Genetics 1998
- E3strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
Across 258 systematically screened MEN1 carriers, the earliest tumour manifestation ranged from 9 years to 25 years depending on tumour type and the latest from 68 to 77 years, with penetrance not predictable from mutation type.
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. The 9-year figure is the earliest observed manifestation in that cohort, not a lower bound on what is biologically possible, and screening did not begin in infancy.
Evidence that argues against this (1)
- The earliest manifestations in that series are the least transferable observations in it: a 9-year-old carrier has had monoallelic menin loss in every cell for nine years. Median treatment duration on the pivotal menin-inhibitor cohort was ten weeks. The two exposures are not the same quantity measured over different spans. Clinical Endocrinology 2007
- E4established confidence 5 of 5: Multiple independent lines of evidence; treated as settled in the field.database
Across the pooled revumenib safety population of 241 patients, the median duration of exposure was 2.5 months with a range of under 1 to 40 months, and 10% of patients were exposed for more than 6 months.
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 6.1 on 2026-09-18. Exposure in a relapsed/refractory registration population is truncated by death, progression and transplant, so it understates the exposure a future front-line or maintenance population would receive. FDA's own postmarketing requirement specifies at least 3 years of treatment for the patients it enrols.
Evidence that argues against this (1)
- The exposure distribution is not fixed. Post-transplant maintenance revumenib in the pivotal trial ran to 199 days at data cut-off with patients still on drug, and the drug is being moved into front-line and combination settings. A median of 2.5 months describes salvage therapy in dying patients, not the exposure a cured child on maintenance would receive. Issa GC et al. 2024
- E5strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
In MEN1-deficient pancreatic neuroendocrine tumours, beta-catenin signalling is activated; conditional knockout of beta-catenin suppresses tumorigenesis and growth of Men1-deficient PNETs and significantly prolongs survival in mice, and blockade of beta-catenin has no adverse effect on physiological pancreatic beta-cell function.
Targeting beta-catenin signalling for therapeutic intervention in MEN1-deficient pancreatic neuroendocrine tumours · Jiang X, Cao Y, Li F, Su Y, Li Y, Peng Y, Cheng Y, Zhang C, Wang W, Ning G · Nat Commun 5:5809 2014What this evidence cannot show
Read as abstract. Mouse and human PNET material; establishes that menin loss requires a further signalling node to produce tumour, which constrains how directly a transient drug exposure could initiate one.
Evidence that argues against this (1)
- Beta-catenin activation is described in ESTABLISHED MEN1-deficient tumours and its knockout suppresses their growth, which is a tumour-maintenance result. Maintenance mechanisms in an existing neoplasm say little about the probability of initiating one, and this entry is about latency to initiation. Nature Communications 2014
- E6strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
In the GTE cohort of 160 patients with MEN1 disease before 21 years, first symptoms occurred before 10 years of age in 22 patients (14%) and before 5 years in 5 patients (3%); the authors concluded that MEN1 lesions occur frequently before 21 but mainly after 10 years of age, with rare aggressive tumours developing at any age.
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. An early-onset-selected cohort, so 14% and 3% are proportions within that cohort and not population penetrance at those ages.
Evidence that argues against this (1)
- Fourteen per cent of a paediatric MEN1 cohort having first symptoms before age ten is a statement about germline carriers ascertained through family screening, which enriches for early and severe disease. It is the correct denominator for counselling a carrier family and the wrong one for a leukaemia patient with intact MEN1. Journal of Clinical Endocrinology & Metabolism 2015
- E7strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
Physiological menin down-regulation of about 50% in the beta cell permits adaptive proliferation; preventing it causes gestational diabetes in mice.
Menin controls growth of pancreatic beta-cells in pregnant mice and promotes gestational diabetes mellitus. · Karnik SK, Chen H, McLean GW, Heit JJ, Gu X, Zhang AY, et al. · Science 2007What this evidence cannot show
Mouse pregnancy; the 50% magnitude comes from a companion prolactin-receptor study.
Evidence that argues against this (1)
- The physiological fall is bounded by a stimulus that ends, which a prescription is not. Syndax Pharmaceuticals et al. 2026
- E8strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
Acute inducible Men1 excision reverses pre-existing hyperglycaemia in three diabetic mouse models.
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
Mouse; genetic; no long-term tumour follow-up.
Evidence that argues against this (1)
- The same manipulation followed longer gives glucagon-expressing tumours and beta-cell identity loss. Li F et al. 2015
- E9moderate confidence 3 of 5: One strong study, or several smaller consistent ones.paper
A menin inhibitor given for 12 weeks increased beta-cell mass and improved glucose handling in diabetic mice.
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, no neoplasia assessment, no off-drug arm.
Evidence that argues against this (1)
- Absence of a reported tumour in a study that did not look for one is absence of measurement. Syndax Pharmaceuticals et al. 2026
the mouse anchor: hyperplastic islets at 2 months, insulinoma at 6, with complete biallelic loss
the human anchor: 7% at age 10 with permanent germline haploinsufficiency
- ← depends onThe reversibility question: months of partial occupancy against a syndrome built from decades of loss
the drug exposure sits between the two anchors and is bounded by neither
supplies the restoration arm that no published conditional Men1 study has
Adds a third exposure class the latency entry does not consider: bounded, reversible, physiological ~50% menin reduction that the healthy beta cell performs on itself without neoplasia
The latency entry records only the neoplastic end of beta-cell Men1 loss; the same manipulation reverses established diabetes in three models before that, so the curve has a beneficial early phase the entry omits
The latency entry brackets the question with two exposure classes (complete ablation, germline heterozygosity) and treats the drug as sitting 'in neither bracket'; there are at least four classes and the physiological and pharmacological ones both have data the entry omits