HEREDITARY ENDOCRINE TUMOURS: CURRENT STATE-OF-THE-ART AND RESEARCH OPPORTUNITIES: The state of science in medullary thyroid carcinoma: current challenges and unmet needs

Metastatic medullary thyroid carcinoma (MTC): disease course, treatment modalities and factors predisposing for drug resistance

PURPOSE

MTC has varying clinical course. In cases with metastatic disease (meta-MTC) further therapeutic modalities (locoregional and/or Tyrosine-Kinase-Inhibitors, TKIs) are needed. Clinical features, disease progression, response to therapy and possible factors predisposing to TKIs response-resistance in meta-MTCs were investigated.

METHODS

Out of 338 MTC patients 54 had meta-MTC and were followed for 0.7-46 years (median 10.5); therapeutic interventions and response to therapy were recorded retrospectively.

RESULTS

Of 54 meta-MTC patients, 34/54 were men, 44/54 sporadic (age-at-diagnosis 47 ± 17.4 years, range: 5-78). Distant metastases at diagnosis were present in 12/54 (≥2 loci in 8/12), 7/12 received TKIs; During follow-up metastases occurred in 42/54 (within 0.6-25 years from diagnosis, median 5 yrs). Locoregional therapies were administered to 44/54 (81.5%) and TKIs to 40/54 (74.1%). Vandetanib was administered in 30 patients (24 as first-line therapy). The median progression-free-survival, PFS) was 48 months (range 4-120), partial response (PR): 26.7%, stable disease (SD): 23.3%, progressive disease (PD): 50.0%, cancer-specific survival: 44.8%, (16 in ongoing-therapy). More favorable disease course was recorded in familial-MTC compared to sporadic (p = 0.02) and in those patients with serious-adverse-events (SAEs) under treatment (p = 0.027). Those with biochemical progression under vandetanib, later showed more frequently structural progression (p = 0.007). Ten patients received cabozantinib (8/10 as second-line therapy, median PFS:11 months (3-36 months), 8/10 died). Three RET-mutant patients received selpercatinib; all showed PR. Within the total follow-up period, the response to therapy was: PR: 8/54 (14.8%), SD: 15/54 (27.8%), PD: 31/54 (57.4%), cancer-specific survival 46.3%. Mortality was higher in older patients (≥60 years) compared to younger ones (<60 yrs) (83.3 vs 45.2%, p = 0.021). Outcome was better in familial-MTC vs sporadic (PR: 50 vs 6.8%, SD: 20 vs 29.5%, PD: 30 vs 59.1%, p = 0.007).

CONCLUSIONS

Meta-MTCs treatment results in disease stabilization in 42.6% during a median 10.5 year follow-up. Combination of locoregional and systemic therapies may result in more favorable PFS. Family history, younger age, SAEs may predict better response; biochemical escape under TKI needs to be followed-up closely as it may indicate disease progression.

Hereditary Endocrine Tumor Registries

Context

Endocrine neoplasia syndromes are phenotypically complex, and there is a misconception that they are universally rare. Genetic alterations are increasingly recognized; however, true prevalence is unknown. The purpose of a clinical registry is to monitor the quality of health care delivered to a specified group of patients through the collection, analysis, and reporting of relevant health-related information. This leads to improved clinical practice, decision-making, patient satisfaction, and outcome.

Objective

This review aims to identify, compare, and contrast active registries worldwide that capture data relevant to hereditary endocrine tumors (HETs).

Methods

Clinical registries were identified using a systematic approach from publications (Ovid MEDLINE, EMBASE) peer consultation, clinical trials, and web searches. Inclusion criteria were hereditary endocrine tumors, clinical registries, and English language. Exclusion criteria were institutional audits, absence of clinical data, or inactivity. Details surrounding general characteristics, funding, data fields, collection periods, and entry methods were collated.

Results

Fifteen registries specific for HET were shortlisted with 136 affiliated peer-reviewed manuscripts.

Conclusion

There are few clinical registries specific to HET. Most of these are European, and the data collected are highly variable. Further research into their effectiveness is warranted. We note the absence of an Australian registry for all HET, which would provide potential health and economic gains. This review presents a unique opportunity to harmonize registry data for HET locally and further afield.

MANAGEMENT OF ENDOCRINE DISEASE: Medullary thyroid cancer: from molecular biology and therapeutic pitfalls to future targeted treatment perspectives

During the last decades, knowledge of the molecular biology in medullary thyroid carcinoma (MTC) and specifically on the role of rearranged during transfection (RET)-activating mutations in tumorigenesis has led to the evolution of novel targeted therapies, mainly tyrosine kinase inhibitors (TKIs). Vandetanib and cabozantinib have been approved for the management of metastatic progressive MTC. Two novel, highly selective RET inhibitors, selpercatinib and pralsetinib, have recently been approved for the treatment of RET-mutant MTCs and RET-fusion differentiated thyroid cancer. The administration of targeted therapies in MTC patients has changed the therapeutic strategies; however, in the majority of cases, there are no real data showing an improvement of prognosis by TKIs in MTC. Drug resistance remains the main reason for treatment failure. Thus, the understanding of the molecular landscape of tumorigenesis and the mechanisms underlying resistance to targeted therapies is of paramount importance for the further development of more efficient therapies for MTC. The present review focuses on the molecular pathways implicated in MTC tumorigenesis, the approved targeted therapies, the tumoral escape mechanisms, as well as the future perspectives for targeted therapy.

DPP4 Is a Potential Prognostic Marker of Thyroid Carcinoma and a Target for Immunotherapy

DPP4 (dipeptidyl peptidase 4) is expressed in many cancers, but the relationship between DPP4 and thyroid carcinoma (THCA) is incompletely understood. We aim to explore the expression of DPP4 in THCA and the correlation between DPP4 expression with the prognosis of THCA and antitumor immunity. We systematically analyzed data from The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), and Gene Expression Omnibus (GEO) databases and explored DPP4 expression, its impact on prognosis, and its relationship with antitumor immunity in THCA. Next, we collected 18 pairs of fresh THCA and adjacent paracancerous tissues and performed RT-qPCR to validate the DPP4 mRNA level. Concurrently, immunohistochemistry (IHC) analysis was performed on 12 pairs of paraffin-embedded tissues of medullary thyroid carcinoma (MTC) and paracancerous tissues to validate the DPP4 protein level. Bioinformatics analysis showed that DPP4 mRNA expression in THCA was significantly higher than that in paracancerous tissues (p < 0.01). DPP4 was expressed at the highest levels in MTC than in other pathological types. The DPP4 expression level was different between groups with different clinical characteristics. The higher the DPP4 expressed in THCA, the lower the disease-free survival (DFS) was (HR = 1.8, p=0.048). DPP4 was significantly correlated with immune cell infiltration and immune response and was positively associated with 21 immune checkpoint genes (ICGs) in THCA (p < 0.05). The results of RT-qPCR showed that the relative mRNA expression of DPP4 was significantly upregulated in 18 THCA tissues compared to that in paracancerous tissues (p=0.011). IHC results showed that the DPP4 protein level was higher in 12 MTC tissues than in paracancerous tissues (p=0.011). In conclusion, DPP4 is a potential prognostic marker of THCA and may become an effective target for immunotherapy.

Immune Profiling of Medullary Thyroid Cancer-An Opportunity for Immunotherapy

Medullary thyroid cancer (MTC) is a rare malignancy that arises from calcitonin-producing C-cells. Curative treatment for patients with metastatic MTC is challenging. Identifying the mechanisms by which cancer cells inhibit the activity of immune cells provides an opportunity to develop new therapies that restore anticancer activity. Little is known about the immunological phenomena underlying MTC. Here, we examined the expression profile of 395 genes associated with MTC. The study included 51 patients diagnosed with MTC at a single center. Bioinformatical analysis revealed that CD276 expression in MTC cells was at least three-fold higher than that in normal tissue. The expression of CD276 showed a weak but statistically significant positive correlation with tumor diameter, but we did not find a significant association between CD276 expression and other histopathological clinical factors, or the response to initial therapy. A search of published data identified the monoclonal antibody (inhibitor) enoblituzumab as a potential drug for patients diagnosed with MTC overexpressing CD276.