Prognostic and predictive roles of MGMT protein expression and promoter methylation in sporadic pancreatic neuroendocrine neoplasms

Temozolomide-based combination for advanced neuroendocrine neoplasms: a systematic review of the literature

BACKGROUND

In this systematic review, we explored the value of using temozolomide (TMZ)-based combinations for advanced neuroendocrine neoplasms (NENs).

METHODS

Database search were conducted using the terms 'NENs' and 'TMZ' and 'systemic therapy.' Outcomes of interest included progression-free survival and overall survival, toxicities and tumor response.

RESULTS

In total, 16 trials including 348 patients were included. Median progression-free survival ranged from 6 to 31 months. The disease control rate ranged from 65 to 100%. Frequently reported grade 3/4 toxicities were leukopenia, lymphopenia and elevated transaminases.

CONCLUSION

The published clinical data suggest that TMZ-based combination with some anticancer agents (especially capecitabine) could be an effective treatment option for advanced low-intermediate grade NENs.

Histopathology of NET: Current concepts and new developments

The diagnosis of neuroendocrine tumors is based on their histopathologic appearance and immunohistochemical profile. With the WHO 2010 classification formal staging and grading was introduced for gastro-entero-pancreatic NET, however, the nomenclature for lung neuroendocrine tumors still relies on the carcinoid term. In this review we also focus on the situation of neuroendocrine carcinoma of unknown primary, tissue biomarkers and actual controversies in the histopathology of NEN.

Streptozocin-Based Chemotherapy in Patients with Advanced Neuroendocrine Neoplasms--Predictive and Prognostic Markers for Treatment Stratification

BACKGROUND AND AIM

Chemotherapy with streptozocin (STZ) in combination with 5-FU or doxorubicin (Dox) represents a standard of care for patients with metastatic pancreatic neuroendocrine neoplasms (pNEN). However, predictive markers for patient selection are still missing. The aim of this study was a retrospective evaluation of the clinicopathological characteristics of pNEN patients receiving STZ-based chemotherapies and to identify predictive and prognostic markers.

PATIENTS AND METHODS

We retrospectively analyzed 77 patients treated at our center between 1995 and 2013. The median overall survival (OS) and progression-free survival (PFS) were calculated using Kaplan-Meier and Cox regression methods, respectively. Uni- and multivariate analyses were performed.

RESULTS

The median PFS (mPFS) in patients receiving STZ/5-FU/Dox was 16 months with a median OS (mOS) of 28 months. Objective response rate (ORR) and disease control rate (DCR) were 34% and 72%, respectively. Biochemical response and positive octreotide scintigraphy predicted objective response. Univariate analysis revealed Ki-67 > 10% and the absence of biochemical or objective response by imaging as independent risk factors for shorter PFS. Additionally, performance status (PS) and resection of the primary tumor were observed to influence mOS. Treatment was well tolerated with less than 10% grade 3 and 4 toxicities.

CONCLUSIONS

STZ-based chemotherapy is an effective and well-tolerated treatment option in patients with well differentiated neuroendocrine neoplasms. Positive octreotide scintigraphy and biochemical response predict objective response.

Personalized medicine for gastroenteropancreatic neuroendocrine tumors: a distant dream?

Neuroendocrine tumors are heterogeneous cancers that can present with advanced disease. Treatment stratification is often based on limited characterization of tumor behavior from histological grade and imaging assessments. Personalized medicine strategies focus on tailoring therapy through characterization of cancer pathways and the development of biomarkers. This review article explores the current personalized medicine landscape in gastroenteropancreatic neuroendocrine tumors, from tissue and circulating biomarkers development through to tumor heterogeneity and reimbursement issues.

Evolution in the treatment of gastroenteropancreatic-neuroendocrine neoplasms, focus on systemic therapeutic options: a systematic review

ABSTRACT 

Neuroendocrine neoplasms (NENs) are a group of heterogeneous tumors. The present review discusses current therapeutic strategies for the treatment of gastro-entero-pancreatic NEN. Several systemic options are currently available, including medical systemic chemotherapy, biological drugs, somatostatin analogs and peptide receptor radionuclide therapy. The carcinoid syndrome can be adequately controlled with somatostatin analogs; chemotherapy has shown positive outcomes in poor prognosis patients, and peptide receptor radionuclide therapy is a promising treatment based on the use of radioisotopes for advanced disease expressing somatostatin receptors. Targeted therapies, such as multikinase inhibitors and monoclonal antibodies are also recommended or under evaluation for the treatment of advanced NENs, but some critical issues in clinical practice remain unresolved. Depending upon the development of the disease, a multimodal approach is recommended. The treatment strategy for metastatic patients should be planned by a multidisciplinary team in order to define the optimal sequence of treatments.

Gemcitabine and oxaliplatin or alkylating agents for neuroendocrine tumors: Comparison of efficacy and search for predictive factors guiding treatment choice

BACKGROUND

The alkylating agents (ALKYs) streptozotocin, dacarbazine, and temozolomide currently are the main drugs used in systemic chemotherapy for neuroendocrine tumors (NETs). The promising activity shown by gemcitabine and oxaliplatin (GEMOX) in previous studies prompted this study 1) to confirm the use of GEMOX in a larger population of NET patients, 2) to compare its efficacy with that of ALKYs, and 3) to explore whether the O(6) -methylguanine-DNA methyltransferase (MGMT) status could help in selecting the chemotherapy regimen.

METHODS

One hundred four patients with metastatic NETs (37 pancreatic NETs, 33 gastrointestinal NETs, 23 bronchial NETs, and 11 NETs of other/unknown origin) were treated with GEMOX between 2004 and 2014. Among these patients, 63 also received ALKYs. MGMT promoter gene methylation was assessed via pyrosequencing in 42 patients.

RESULTS

Patients received a median of 6 courses of GEMOX. Twenty-four (23%) had an objective response (OR). The median progression-free survival (PFS) and overall survival were 7.8 and 31.6 months, respectively. In the 63 patients treated with both ALKYs and GEMOX, the ORs (22% and 22%) and the PFSs (7.5 and 7.3 months) were similar. The response was concordant in 53% of the patients. Promoter gene methylation of MGMT was associated with better outcomes with ALKYs (P = .03 for OR and P = .04 for PFS) but not GEMOX.

CONCLUSIONS

GEMOX is effective against NETs; its activity is comparable to that of ALKYs, and it is not influenced by the MGMT status. Our data suggest that GEMOX might be preferred for patients with unmethylated MGMT tumors. Cancer 2015;121:3435-43. © 2015 American Cancer Society.

The p53 network as therapeutic target in gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are heterogeneous and especially the midgut tumors currently lack effective therapy options. Actionable driver mutations as therapeutic targets are rare. Subtype specific data concerning regulatory mechanisms or epigenetic aberrations are necessary for novel clinical trials. Although the p53 protein itself is rarely mutated in GEP-NENs, epigenetic and regulatory aberrations interfere with the p53 network activity and might function as s target for novel therapeutic approaches. In this review we analyze the current knowledge about the p53 network in GEP-NENs and discuss three possible strategies that include recovering p53 function, enforcing apoptosis by genotoxic stress induction and restoring silenced gene function, based on in vitro, in vivo and clinical data.

O6-Methylguanine-DNA methyltransferase status in neuroendocrine tumours: prognostic relevance and association with response to alkylating agents

Background:

O⁶-Methylguanine-DNA methyltransferase (MGMT) loss of expression has been suggested to be predictive of response to temozolomide in neuroendocrine tumours (NETs), but so far, only limited data are available. We evaluated the prognostic and predictive value of MGMT status, assessed by two molecular methods and immunohistochemistry, in a large series of NETs of different origins.

Methods:

A total of 107 patients, including 53 treated by alkylants (temozolomide, dacarbazine or streptozotocin), were retrospectively studied. In each case, we used methyl-specific PCR (MS-PCR) and pyrosequencing for evaluation of promoter methylation and immunohistochemistry for evaluation of protein status.

Results:

MGMT promoter methylation was detected in 12 out of 99 (12%) interpretable cases by MS-PCR and in 24 out of 99 (24%) by pyrosequencing. O⁶-Methylguanine-DNA methyltransferase loss of expression was observed in 29 out of 89 (33%) interpretable cases. Status of MGMT was not correlated with overall survival (OS) from diagnosis. Progression-free survival and OS from first alkylant use (temozolomide, dacarbazine and streptozotocin) were higher in patients with MGMT protein loss (respectively, 20.2 vs 7.6 months, P<0.001 and 105 vs 34 months, P=0.006) or MGMT promoter methylation assessed by pyrosequencing (respectively, 26.4 vs 10.8 months, P=0.002 and 77 vs 43 months, P=0.026).

Conclusions:

Our results suggest that MGMT status is associated with response to alkylant-based chemotherapy in NETs.