The cheapest missing experiment in this beat: put revumenib on a parathyroid cell
also called parathyroid cell menin inhibitor assay · TGF-beta PTH secretion revumenib
Nobody has ever put a menin-blocking drug onto parathyroid cells. Take cells from a routine parathyroid operation, add the drug, and see whether the cells stop obeying the signal that normally tells them to make less parathyroid hormone.
The same thing, for a scientist
A search of PubMed on 2026-09-19 for any menin-inhibitor term co-occurring with parathyroid, PTH or hypercalcaemia in title or abstract returns **zero records**, against 118 records for 'menin inhibitor' and 167 for 'menin AND parathyroid' [E1]. The mechanism is established: menin is required for TGF-beta to inhibit parathyroid cell proliferation **and PTH secretion**, and menin inactivation abolishes both responses [E2]. The clinical observation is established: intact PTH rose in 34% of revumenib-treated patients [E3]. The step between them has simply never been taken. This experiment takes it, in primary human parathyroid tissue that is discarded after routine parathyroidectomy.
Design
Tissue. Primary parathyroid cells dispersed from surgical specimens: (a) secondary hyperparathyroidism from renal disease (the tissue used in the founding study, readily available), and (b) sporadic adenoma, and if obtainable (c) normal rim tissue. n = 6-8 donors per group.
Arms. Vehicle; TGF-beta1 alone; TGF-beta1 + revumenib across a concentration range spanning and exceeding the clinically achieved unbound plasma concentration; TGF-beta1 + ziftomenib; TGF-beta1 + MI-503 as a positive tool control; menin siRNA as the genetic positive control.
Primary readouts. (1) PTH secretion into the medium at 24 and 72 h; (2) proliferation (EdU or Ki67). Secondary: PTH and CASR mRNA, menin ChIP or proximity ligation at TGF-beta target loci, Smad2/3 phosphorylation to confirm the pathway is intact upstream.
The number that matters. The ratio of the concentration that abolishes TGF-beta suppression of PTH secretion to the concentration that displaces KMT2A from menin in the same lysate. This is the parathyroid analogue of the JunD:KMT2A ratio that exp-jund-displacement-coip-under-clinical-menin-inhibitor identifies as the missing dosing number.
Interpretation, both ways
- Effect at or below clinical concentrations: the labelled PTH rise is on-target, the renal explanation is demoted, and paediatric calcium and PTH monitoring becomes mandatory rather than optional.
- No effect at achievable concentrations: the parathyroid arm of this beat is substantially withdrawn, the renal secondary-hyperparathyroidism explanation wins, and several entries in
endocrine/need their confidence lowered. This is a real possibility and the experiment should be run by someone willing to publish that result. - Effect only far above clinical concentrations: the hazard is confined to overdose or to accumulation in renal or hepatic impairment, which is an actionable and specific warning.
Why it has not been done
Speculative, but worth stating: the diabetes-facing menin literature works in islets and has no reason to touch the parathyroid; the leukaemia-facing literature works in haematopoietic cells and treats endocrine tissue as a toxicology question for regulators; and the toxicology packages use whole-animal histopathology, which detects hyperplasia but not secretory disinhibition. The parathyroid falls between three communities, which is exactly the kind of gap a knowledge graph exists to surface.
| design | Primary human parathyroid cell culture from surgical specimens; TGF-beta1 challenge with and without clinical menin inhibitors across a concentration range, against menin siRNA and MI-503 controls |
|---|---|
| readout | PTH secretion at 24 and 72 h; proliferation; ratio of PTH-disinhibiting concentration to KMT2A-displacing concentration in the same lysate |
| controls | vehicle, TGF-beta1 alone, menin siRNA positive control, Smad2/3 phosphorylation to confirm intact upstream signalling |
| cost tier | low |
| timeline | 6-9 months including tissue accrual |
| n | 6-8 donors per tissue group |
- A clean negative would withdraw a substantial part of this beat, and the beat should say so in advance rather than after.
- If the effect appears at clinically achievable concentrations, every child on a menin inhibitor needs calcium and PTH monitoring that no protocol currently requires.
- The experiment cannot address duration or reversibility, which are the questions that actually determine paediatric harm.
- Is discarded parathyroid tissue from routine parathyroidectomy obtainable under existing consent at a centre that also treats leukaemia?
- What is the unbound plasma concentration of revumenib at the approved paediatric dose? The label reports total exposure; unbound concentration is the relevant comparator and is not obviously public.
- Would a parathyroid organoid system be a better substrate than dispersed primary cells?
- E1moderate confidence 3 of 5: One strong study, or several smaller consistent ones.database
No published study has exposed parathyroid cells or tissue to a menin inhibitor.
REVUFORJ (revumenib) tablets, for oral use - US Prescribing Information (SPL version 5, published 20 Feb 2026) · Syndax Pharmaceuticals, Inc. · DailyMed / FDA Structured Product Label, setid 6eb3cdbc-0e74-477d-82d6-3bb172d3f63f 2026What this evidence cannot show
An absence established by a title/abstract search on 2026-09-19 with both halves controlled (118 and 167 records respectively); a study reporting this as an unindexed secondary finding, or in a thesis, conference abstract or regulatory document, would be missed.
Evidence that argues against this (1)
- The sponsors' nonclinical packages include 13-week repeat-dose toxicology in rats, mice and dogs which would have examined parathyroid histology; those study reports are not public, so a negative parathyroid histology finding may already exist unpublished. Kura Oncology et al. 2025
- E2moderate confidence 3 of 5: One strong study, or several smaller consistent ones.paper
Menin is required for TGF-beta-mediated inhibition of parathyroid cell proliferation and PTH secretion.
Menin inactivation leads to loss of transforming growth factor beta inhibition of parathyroid cell proliferation and parathyroid hormone secretion. · Sowa H, Kaji H, Kitazawa R, Kitazawa S, Tsukamoto T, Yano S, et al. · Cancer Research 2004What this evidence cannot show
Antisense knockdown in primary cells from secondary hyperparathyroidism; single MEN1 patient comparator.
Evidence that argues against this (1)
- Knockdown removes the protein; a pocket inhibitor may leave the TGF-beta-relevant surface intact, in which case this mechanism is not drug-accessible and the experiment returns a clean negative. Ma J et al. 2021
- E3established confidence 5 of 5: Multiple independent lines of evidence; treated as settled in the field.database
Intact PTH increased in 34% of revumenib-treated patients, with hyperparathyroidism listed under Endocrine disorders.
REVUFORJ (revumenib) tablets, for oral use - US Prescribing Information (SPL version 5, published 20 Feb 2026) · Syndax Pharmaceuticals, Inc. · DailyMed / FDA Structured Product Label, setid 6eb3cdbc-0e74-477d-82d6-3bb172d3f63f 2026What this evidence cannot show
Confounded by creatinine and phosphate; no off-treatment values.
Evidence that argues against this (1)
- No parathyroid signal appears on the ziftomenib label, so the finding is single-compound. Kura Oncology et al. 2025
P5: does a clinical menin inhibitor abolish TGF-beta suppression of PTH secretion at or below KMT2A-displacing concentrations?
Takes the one step never taken: the mechanism was established with antisense knockdown in 2004 and no menin inhibitor has ever been applied to a parathyroid cell
Would discriminate the on-target reading of the labelled 34% PTH elevation from the renal secondary-hyperparathyroidism null
- co-occurs with →Does revumenib displace JunD, and at what concentration relative to KMT2A? (The yes/no half is already answered)
Same missing number in a different tissue: the ratio of the endocrine-disinhibiting concentration to the KMT2A-displacing concentration in the same lysate