HSP90 expression and early recurrence in gastroenteropancreatic neuroendocrine tumors: Potential for a novel therapeutic target

BACKGROUND

Heat shock protein (HSP)-90 promotes tumor growth and is overexpressed in many malignancies. HSP90 expression profile and its potential as a therapeutic target in primary and metastatic neuroendocrine tumors (NETs) are not known.

METHODS

HSP90 cytoplasmic expression and Ki-67 index were re-reviewed and scored by a pathologist blinded to all other clinicopathologic variables for patients who underwent resection of primary and metastatic gastroenteropancreatic (GEP) neuroendocrine tumors at a single institution (2000-2013). Primary outcome was recurrence-free survival (RFS).

RESULTS

Of 263 tumors reviewed, 73% (n = 191) were primary GEP NETs, and 12% (n = 31) were NET liver metastases. Of the primary GEP-NETs, mean age was 56 years, 42% were male; 53% (n = 103) were pancreatic and 23% (n = 44) were small bowel. HSP90 expression was high in 34% (n = 64) and low in 66% (n = 127). Compared to low expression, high HSP90 was associated with advanced T-stage (T3/T4) (47 vs 27%; p = 0.02). Among patients who underwent curative-intent resections for primary, non-metastatic NETs (n = 145), high HSP90 was independently associated with worse RFS (HR 5.09, 95% CI 1.65-15.74; p = 0.005), after accounting for positive margin, LN involvement, increased tumor size, site of primary tumor, and Ki-67. When assessing NET liver metastases, 13% (n = 4) had high HSP90 expression and 87% (n = 26) had low expression. Patients with liver metastases with high HSP90 tended to have worse 1- and 3-year progression-free survival (25%, 25%) compared to those with low HSP90 (69%, 49%; p = 0.059).

CONCLUSION

HSP90 exhibits differential expression in resected GEP-NETs and liver metastases. High cytoplasmic expression is associated with early disease recurrence, even after accounting for other adverse pathologic factors. HSP90 inhibition may be a potential therapeutic target for neuroendocrine tumors.

STAT3 Inhibition for Gastroenteropancreatic Neuroendocrine Tumors: Potential for a New Therapeutic Target?

BACKGROUND

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are highly vascular neoplasms treated similarly, irrespective of tumor location. The expression of pro-angiogenic factors (STAT3, VEGF, and HIF-1α) and their association with adverse pathologic factors and disease recurrence following resection remains unclear.

METHODS

All patients with non-metastatic GEP-NETs who underwent curative-intent resection from 2000 to 2013 were included. Immunohistochemistry was performed for pro-angiogenic factors, Ki-67 index, and CD31 using tissue microarrays made in triplicate by a pathologist blinded to other clinicopathologic variables. Primary outcome was a 3-year recurrence-free survival (3-yrRFS); secondary outcomes were correlation of pro-angiogenic factors with Ki-67 index, adverse pathologic factors, and CD31 expression, a marker of microvascular density.

RESULTS

Of 144 GEP-NETs resected, STAT3 expression was high in 12 (8%) and low in 132 (92%) pts. High STAT3 expression was associated with worse 3-yrRFS compared to low expression (55% vs 84%; p = 0.003). High VEGF expression had a 3-yrRFS of 76% vs 82% for low expression (p = 0.09). HIF-1α expression was not associated with RFS. Ki-67 ≥ 3% was associated with worse 3-yrRFS (≥ 3%: 51% vs < 3%: 84%; p < 0.001), as was the presence of increased microvascular density (CD31 > median: 75% vs CD31 < median: 86%; p = 0.04). High STAT3 expressing tumors were more likely to have a Ki-67 ≥ 3% (42% vs 7%; p < 0.001). LVI was present in 82% of high STAT3 tumors compared to only 50% with low STAT3 (p = 0.058). CD31 expression was similar between groups (58% vs 49%; p = 0.5).

CONCLUSIONS

In resected GEP-NETs, high STAT3 expression is associated with an increased Ki-67 index, presence of lymphovascular invasion and worse 3-yr RFS. STAT3 may be a novel therapeutic target for patients undergoing resection of high-risk tumors.

Corticosteroids for Posttransplant Immune Reconstitution Syndrome in Cryptococcus gattii Meningoencephalitis: Case Report and Literature Review

Cryptococcus gattii represents an emerging fungal pathogen of immunocompromised and immunocompetent hosts in the United States. To our knowledge, this is the first case of posttransplant immune reconstitution syndrome due to C. gattii meningoencephalitis successfully treated with corticosteroids. We also report successful maintenance phase treatment with isavuconazole, a novel triazole, following fluconazole-induced prolonged QT syndrome.

STAT3 inhibition for gastroenteropancreatic neuroendocrine tumors: Potential for a new therapeutic target?

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Background: Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are highly vascular tumors with similar treatments applied to all sites. The expression of pro-angiogenic factors (STAT3, VEGF, and HIF-1α) and their association with known adverse pathologic factors and disease recurrence after resection is not known. Methods: All pts with non-metastatic primary GEP-NETs who underwent curative-intent resection at a single institution from 2000-2013 were included. Immunohistochemistry was performed for STAT3, VEGF, HIF-1α, Ki-67 index, and CD31 using tissue microarrays made in triplicate by a pathologist blinded to other clinicopathologic variables. STAT3, VEGF, and HIF-1α were categorized into high vs low expression; CD31 was dichotomized at the median value. Primary outcome was 3-yr recurrence-free survival (3-yr RFS); secondary outcomes were correlation of STAT3, VEGF, and HIF-1α expression with Ki-67 index, adverse pathologic factors, and CD31 expression, a marker of microvascular density. Results: Of 265 GEP-NETs resected, 144 had tissue for analysis. STAT3 expression was high in 12 (8%) and low in 132 (92%). VEGF expression was high in 19 (13%) and low in 125 (87%), and HIF-1α was high in 1 (1%) and low in 143 (99%). High STAT3 expression was associated with worse 3-yr RFS compared to low expression (55% vs 84%; p = 0.003). High VEGF expression had a 3-yr RFS of 76% compared to 82% for low expression (p = 0.098); HIF-1α expression was not associated with RFS. Ki-67 ≥3% was associated with worse 3-yr RFS (≥3%: 51% vs < 3%: 84%; p < 0.001), as was the presence of lymphovascular invasion (LVI: 72% vs 95%; p = 0.001) and increased microvascular density per µm2 (CD31 > median: 75% vs CD31 < median: 86%; p = 0.043). High STAT3 expressing tumors were more likely to have a Ki-67≥3% (42% vs 7%; p < 0.001). LVI was present in 82% of high STAT3 tumors compared to only 50% with low STAT3 (p = 0.058). CD31 overexpression was similar between groups (58% vs 49%; p = 0.5). Conclusions: In resected GEP-NETs, high STAT3 expression is associated with an increased Ki-67 index, presence of lymphovascular invasion, and worse 3-yr RFS. STAT3 inhibition may be a novel therapeutic option for patients undergoing resection of high-risk tumors.

Redefining the Ki-67 Index Stratification for Low-Grade Pancreatic Neuroendocrine Tumors: Improving Its Prognostic Value for Recurrence of Disease

BACKGROUND

The Ki-67 index is an established prognostic marker for recurrence after resection of pancreatic neuroendocrine tumors (PanNETs) that groups tumors into three categories: low grade (< 3%), intermediate grade (3-20%), and high grade (> 20%). Given that the majority of resected PanNETs have a Ki-67 less than 3%, this study aimed to stratify this group further to predict disease recurrence more accurately.

METHODS

The Ki-67 index was pathologically re-reviewed and scored by a pathologist blinded to all other clinicopathologic variables using tissue microarray blocks made in triplicate. All patients who underwent curative-intent resection of non-metastatic PanNETs at a single institution from 2000 to 2013 were included in the study. The primary outcome was recurrence-free survival (RFS).

RESULTS

Of 113 patients with well-differentiated PanNETs resected, 83 had tissue available for pathologic re-review. The Ki-67 index was lower than 3% for 72 tumors (87%) and between 3 and 20% for 11 tumors (13%). Considering only Ki-67 less than 3%, the tumors were further stratified by Ki-67 into three groups: group A (< 1%, n = 43), group B (1-1.99%, n = 23), and group C (2-2.99%, n = 6). Compared with group A, groups B and C more frequently had advanced T stage (T3: 44% and 67% vs 12%; p = 0.003) and lymphovascular invasion (50% and 83% vs 23%; p = 0.007). Groups B and C had similar 1- and 3-year RFS, both less than group A. After combining groups B and C, a Ki-67 of 1-2.99% was associated with decreased RFS compared with group A (< 1%). This persisted in the multivariable analysis (hazard ratio [HR] 8.6; 95% confidence interval [CI] 1.0-70.7; p = 0.045), with control used for tumor size, margin-positivity, lymph node involvement, and advanced T stage.

CONCLUSIONS

PanNETs with a Ki-67 of 1-2.99% exhibit distinct biologic behavior and earlier disease recurrence than those with a Ki-67 lower than 1%. This new stratification scheme, if externally validated, should be incorporated into future grading systems to guide both surveillance protocols and treatment strategies.

HSP90 expression and early recurrence in gastroenteropancreatic neuroendocrine tumors: Potential for novel therapeutic targets

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Background: Heat shock protein (HSP) 90 promotes tumor growth and is overexpressed in many malignancies. HSP90 expression profile and its potential as a therapeutic target in primary and metastatic neuroendocrine tumors (NETs) are not known. Methods: HSP90 cytoplasmic expression and Ki-67 index were re-reviewed and scored by a pathologist blinded to all other clinicopathologic variables using tissue microarray (TMA) blocks created in triplicate for patients who underwent resection of primary and metastatic gastroenteropancreatic (GEP) neuroendocrine tumors at a single institution from 2000-2013. Primary outcome was recurrence-free survival (RFS). Results: Of 278 tumors reviewed, 194 (68%) were primary GEP NETs, and 31 (11%) were NET liver metastases. Of the primary GEP NETs, mean age was 56yrs, 42% were male; 103 (53%) were pancreas and 44 (23%) were small bowel. HSP90 expression was high in 66 (34%) and low in 128 (66%). Compared to low expression, high HSP90 was associated with lymphovascular invasion (70vs42%; p = 0.049) and advanced T-stage (T3/T4: 48vs27%; p = 0.01). Among patients who underwent curative-intent resections for primary, non-metastatic NETs (n = 147), high HSP90 was associated with decreased 1-, 3-, and 5-yr RFS (80%, 72%, 62%) compared to low (89%, 86%, 83%; p = 0.03), which persisted on multivariable analysis (HR 5.2, 95%CI 1.7-16.0; p = 0.004), after accounting for positive margin, LN involvement, increased tumor size, site of primary tumor, and Ki-67 index. When assessing NET liver metastases, high HSP90 expression was seen in 4 (13%) patients and low in 27 (87%). Similar to primary GEP NETs, patients with liver metastases that exhibited high HSP90 expression had decreased 1-, 3-, and 5-yr progression-free survival (25%, 25%, 0%) compared to those with low HSP90 (69%, 49%, 33%; p = 0.052). Conclusions: Heat shock protein 90 exhibits differential expression in resected GEP NETs and liver metastases. High cytoplasmic expression is associated with early recurrence of disease, even after accounting for other adverse pathologic factors, including Ki-67 index. HSP90 inhibition is a potential target for novel therapeutic strategies for neuroendocrine tumors.