Daily Endocrinology Research Analysis
Three studies reshape endocrine practice and mechanisms today: Cathepsin K drives bone invasion in pituitary adenomas and is druggable with odanacatib in models; a 244,001-cycle SART analysis defines an endometrial thickness threshold (~9 mm) for live birth; and a Swiss national registry natural experiment shows legal reforms can shift ART outcomes without proving freeze-all universally superior.
Summary
Three studies reshape endocrine practice and mechanisms today: Cathepsin K drives bone invasion in pituitary adenomas and is druggable with odanacatib in models; a 244,001-cycle SART analysis defines an endometrial thickness threshold (~9 mm) for live birth; and a Swiss national registry natural experiment shows legal reforms can shift ART outcomes without proving freeze-all universally superior.
Research Themes
- Mechanisms and targets of endocrine tumor invasion
- Embryo transfer optimization in reproductive endocrinology
- Policy-driven changes in assisted reproductive technology outcomes
Selected Articles
1. Role of Cathepsin K in bone invasion of pituitary adenomas: A dual mechanism involving cell proliferation and osteoclastogenesis.
In a 1,437-patient cohort with translational experiments, CTSK was upregulated in bone-invasive pituitary adenomas, predicted worse recurrence-free survival, and drove tumor proliferation via mTOR and osteoclastogenesis via TLR4–RANKL. Pharmacologic inhibition with odanacatib curtailed proliferation and bone invasion in vitro and in vivo, nominating CTSK as a biomarker and therapeutic target.
Impact: This work uncovers a dual mechanism of invasion and provides preclinical evidence that a clinically known CTSK inhibitor can counteract aggressive behavior, bridging molecular insight to therapeutic opportunity.
Clinical Implications: CTSK expression could be used to stratify pituitary adenoma patients for bone invasion risk and recurrence. CTSK inhibition (e.g., odanacatib) warrants clinical evaluation as an adjuvant therapy to limit invasion.
Key Findings
- Approximately 10% of pituitary adenomas exhibited bone invasion, which correlated with shorter recurrence-free survival.
- CTSK expression was increased in bone-invasive tumors and associated with worse prognosis.
- CTSK drove proliferation via mTOR activation and promoted osteoclastogenesis by inducing RANKL through TLR4; odanacatib inhibited these phenotypes in vitro and in vivo.
Methodological Strengths
- Large clinical cohort (n=1,437) with outcome association
- Integrated multi-omics and gain/loss-of-function validation in vitro and in vivo
- Pharmacologic inhibition test (odanacatib) demonstrating targetability
Limitations
- Cohort appears retrospective with potential selection and measurement biases
- No human interventional trial to confirm clinical efficacy of CTSK inhibition
- Generalizability beyond study population requires validation
Future Directions: Prospective validation of CTSK as a prognostic biomarker, and early-phase clinical trials of CTSK inhibitors in invasive pituitary adenomas; mechanistic dissection of TLR4–mTOR crosstalk.
This study aimed to investigate the regulation and underlying mechanism of Cathepsin K (CTSK) in bone-invasive pituitary adenomas (BIPAs). A total of 1437 patients with pituitary adenomas were included and followed up. RNA sequencing, immunohistochemistry, and qRT-PCR were used to analyze CTSK expression. The effects of CTSK on cellular proliferation, bone matrix degradation, and osteoclast differentiation were determined by gain/loss of function experiments in vitro and in vivo. The exploration of signaling pathways was determined through molecular biology experiments. Here, we reported a significant fraction (∼10 %) of pituitary adenoma patients developed bone invasion, which was correlated with tumor recurrence. Patients with BIPAs had shorter recurrence-free survival. CTSK expression was increased in BIPA patients and was strongly associated with a worse prognosis. Increased CTSK expression enhanced pituitary adenoma cell proliferation through the activation of the mammalian target of rapamycin (mTOR) signaling pathway and promoted bone invasion by increasing osteoclast differentiation both in vitro and in vivo. Treatment with the CTSK inhibitor odanacatib effectively inhibited pituitary adenoma cell proliferation and bone invasion in these models. Additionally, CTSK facilitated osteoclast differentiation by promoting RANKL expression in MC3T3-E1 cells via interaction with TLR4. Based on these findings, we conclude that CTSK has the potential to become a novel predictive biomarker and therapeutic target for BIPAs.
2. Association of endometrial thickness with live birth rate: a study using the Society for Assisted Reproductive Technology Clinic Outcome Reporting System.
Across 244,001 IVF cycles, live birth rates increased with endometrial thickness up to 9 mm and then plateaued, consistently across fresh and frozen transfers with or without PGT. Each 1-mm increase below 9 mm was associated with a 13–19% higher odds of live birth depending on cycle type; no decline in live birth was seen above 9 mm.
Impact: Defines a clinically actionable EMT threshold for live birth across transfer types at unprecedented scale, informing counseling and cycle management.
Clinical Implications: Aim to optimize EMT toward ~7–9 mm without over-intervening beyond 9 mm; avoid canceling cycles solely for EMT >9 mm; standardize EMT measurement and counseling across fresh and FET cycles.
Key Findings
- In 244,001 embryo transfer cycles, LBR increased with EMT up to 9 mm, then plateaued.
- Each 1-mm increase in EMT below 9 mm corresponded to a 13–19% higher odds of live birth across cycle types.
- No endometrial thickness above 9 mm was associated with a decrease in live birth rate.
Methodological Strengths
- Exceptionally large national registry cohort with standardized reporting
- Multivariable adjustment across transfer types and PGT status
Limitations
- Retrospective design with potential measurement variability in EMT
- Residual confounding cannot be excluded; causality not established
Future Directions: Prospective studies standardizing EMT assessment and testing endometrial preparation protocols to establish causality and optimize outcomes.
OBJECTIVE: To assess the relationship between endometrial thickness (EMT) and live birth rates (LBRs) in fresh embryo transfer and frozen embryo transfer (FET) with and without preimplantation genetic testing (PGT). DESIGN: Retrospective cohort study using the Society for Assisted Reproductive Technology Clinic Outcome Reporting System. SUBJECTS: Autologous in vitro fertilization fresh embryo transfer and FET cycles initiated in 2019-2020. EXPOSURE: Endometrial thickness measured in millimeters. MAIN OUTCOME MEASURES: Live birth rate. RESULTS: A total of 244,001 embryo transfer cycles met the inclusion criteria (100,419 FET cycles with PGT, 96,249 FET cycles without PGT, and 47,333 fresh embryo transfer cycles). An increase in EMT was associated with an increase in LBR among all cycle types until a threshold of 9 mm, after which there was minimal increase in LBR. Before 9 mm, each 1-mm increase in EMT was associated with a relative increase in the odds of live birth by 19% for FET with PGT (adjusted odds ratio [aOR], 1.19; 95% confidence interval [CI], 1.66-1.22), 13% for FET without PGT (aOR, 1.13; 95% CI, 1.09-1.16), and 15% for fresh embryo transfer (aOR, 1.15; 95% CI, 1.09-1.20). CONCLUSION: The LBR increased with an increase in EMT for fresh and frozen transfers with or without PGT until a threshold of 9 mm, beyond which the LBR plateaued. There was no thickness above 9 mm associated with a decrease in LBR.
3. Legal framework and IVF outcomes: a comparative analysis of fresh and frozen embryo transfers in Switzerland.
A national natural experiment showed that after Swiss legal reform enabling extended culture, frozen transfer outcomes improved and multiple births decreased. Yet, adjusted analyses found no overall live-birth advantage of frozen over fresh or of freeze-all strategies; fresh blastocyst transfers outperformed cleavage-stage transfers.
Impact: Demonstrates how legal frameworks can shape ART outcomes and clinical practice at scale, separating technological gains from policy-driven changes.
Clinical Implications: Supports continued lab optimization and elective single blastocyst transfer; freeze-all should be individualized rather than universally adopted; policy can safely improve outcomes when aligned with practice.
Key Findings
- After legal reform, frozen embryo transfer LBR increased and multiple births decreased; pre-reform, fresh had higher LBR than frozen.
- Adjusted analyses showed no significant difference in live-birth odds between fresh and frozen transfers; freeze-all was not superior overall.
- Fresh blastocyst transfers had higher LBR than cleavage-stage transfers (OR≈2.01).
Methodological Strengths
- Nationwide registry spanning pre/post policy change enabling a natural experiment
- Adjusted multivariable mixed models and subgroup analyses (blastocyst vs cleavage)
Limitations
- Observational design with potential secular trends and confounding by concurrent lab improvements
- Generalizability outside Switzerland may be limited
Future Directions: Prospective comparative studies of fresh vs frozen strategies under standardized lab conditions; policy evaluations linking legal changes to perinatal safety and long-term child outcomes.
RESEARCH QUESTION: To what extent do legislative measures impact standard reproductive outcome parameters? DESIGN: Retrospective cohort study using data from the Swiss national IVF registry analysing the outcomes of 13,908 women undergoing embryo transfers resulting from their first lifetime oocyte retrieval before (2014-2016) or after (2020-2022) revision of the legislation, allowing extended culture for 12 zygotes. Live birth rates (LBR) and cumulative LBR (cLBR) were compared in fresh and frozen embryo transfer strategies in both periods. Adjusted multivariable mixed model analyses were performed to determine OR and incidence rate ratios (IRR). RESULTS: Before revision of the legislation, LBR was higher for fresh embryo transfers compared with frozen embryo transfers (27.2% versus 22.7%; P = 0.006). After revision of the legislation, LBR was lower for fresh embryo transfers (29.3% versus 36.3%; P < 0.001), and cLBR was higher for the freeze-all embryo transfer strategy (59.0% versus 39.8%; P < 0.001). However, in a multivariable analysis, no difference in the odds of live birth was found between fresh and frozen embryo transfers (OR = 1.08, 95% CI 0.95-1.22), and the freeze-all embryo transfer strategy was not found to be more effective than the fresh embryo transfer strategy (IRR = 1.12, 95% CI 0.98-1.27). In a subgroup analysis, fresh blastocyst embryo transfers showed higher LBR than cleavage stage embryo transfers (OR = 2.01, 95% CI 1.62-2.49). CONCLUSION: The change in national legislation provided the unique opportunity to evaluate the legal impact on reproductive outcomes. Besides a reduction in the number of multiple births, LBR in frozen embryo transfers improved, resulting in comparable success of fresh and frozen embryo transfer strategies. In addition to technological improvement, the legal framework influences the evolution of clinical practice, thereby contributing to enhanced reproductive outcomes.