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Imaging of lymph node micrometastases using an oncolytic herpes virus and [F]FEAU PET.

Brader P, Kelly K, Gang S, Shah JP, Wong RJ, Hricak H, Blasberg RG, Fong Y, Gil Z - PLoS ONE (2009)

Bottom Line: Presence of virus-infected tumor cells was successfully imaged with [(18)F]FEAU-PET, that identified 8 out of 8 tumor-positive nodes.There was no overlap between radioactivity levels (lymph node to surrounding tissue ratio) of tumor-positive and tumor-negative lymph nodes.A new approach for imaging SLN metastases using NV1023 and [(18)F]FEAU-PET was successful in a murine model.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America.

ABSTRACT

Background: In patients with melanoma, knowledge of regional lymph node status provides important information on outlook. Since lymph node status can influence treatment, surgery for sentinel lymph node (SLN) biopsy became a standard staging procedure for these patients. Current imaging modalities have a limited sensitivity for detection of micrometastases in lymph nodes and, therefore, there is a need for a better technique that can accurately identify occult SLN metastases.

Methodology/principal findings: B16-F10 murine melanoma cells were infected with replication-competent herpes simplex virus (HSV) NV1023. The presence of tumor-targeting and reporter-expressing virus was assessed by [(18)F]-2'-fluoro-2'-deoxy-1-beta-D-beta-arabinofuranosyl-5-ethyluracil ([(18)F]FEAU) positron emission tomography (PET) and confirmed by histochemical assays. An animal foot pad model of melanoma lymph node metastasis was established. Mice received intratumoral injections of NV1023, and 48 hours later were imaged after i.v. injection of [(18)F]FEAU. NV1023 successfully infected and provided high levels of lacZ transgene expression in melanoma cells. Intratumoral injection of NV1023 resulted in viral trafficking to melanoma cells that had metastasized to popliteal and inguinal lymph nodes. Presence of virus-infected tumor cells was successfully imaged with [(18)F]FEAU-PET, that identified 8 out of 8 tumor-positive nodes. There was no overlap between radioactivity levels (lymph node to surrounding tissue ratio) of tumor-positive and tumor-negative lymph nodes.

Conclusion/significance: A new approach for imaging SLN metastases using NV1023 and [(18)F]FEAU-PET was successful in a murine model. Similar studies could be translated to the clinic and improve the staging and management of patients with melanoma.

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Related in: MedlinePlus

Histologic analysis of lymph nodes after imaging showing metastatic and normal lymph nodes from mice injected with NV1023.(A) LacZ staining (blue) shows diffuse β-galactosidase transgene expression adjacent to metastatic B16-F10 melanoma cells (black cells, scale bar 30 µm). The white arrow indicates the area of micrometastases. (B) High magnification of the area in (A) indicated by the arrow showing diffuse LacZ staining in the area of metastases (scale bar 10 µm). (C) High magnification of a positive lymph node showing non-specific LacZ stain in an area devoid of melanoma cells. (D) Low magnification of a normal lymph node from an animal treated with NV1023. Only a non-specific LacZ staining is seen (scale bar 130 µm).
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pone-0004789-g004: Histologic analysis of lymph nodes after imaging showing metastatic and normal lymph nodes from mice injected with NV1023.(A) LacZ staining (blue) shows diffuse β-galactosidase transgene expression adjacent to metastatic B16-F10 melanoma cells (black cells, scale bar 30 µm). The white arrow indicates the area of micrometastases. (B) High magnification of the area in (A) indicated by the arrow showing diffuse LacZ staining in the area of metastases (scale bar 10 µm). (C) High magnification of a positive lymph node showing non-specific LacZ stain in an area devoid of melanoma cells. (D) Low magnification of a normal lymph node from an animal treated with NV1023. Only a non-specific LacZ staining is seen (scale bar 130 µm).

Mentions: Histopathologic analysis was used to define positive (with melanoma metastases) and negative (no tumor cells) lymph nodes. The presence of NV1023 in sentinel lymph nodes with melanoma micrometastases was verified based on expression of the lacZ transgene. LacZ staining after NV1023 infection in vitro revealed cytoplasmatic expression of β-galactosidase (Figure S1). However melanoma metastatic cells in lymph nodes had dark pigmented cytoplasm, and it was difficult to see the light blue lacZ staining in the cells. Yet, by analyzing whole specimens of lymph nodes with metastases, we found diffuse accumulation of lacZ staining only in areas with metastatic melanoma cells (Fig 4A–C). In contrast, when the same staining was performed on normal lymph nodes of mice injected with NV1023, we noticed only light and non-specific staining of lacZ (Fig 4D). Similarly, positive lymph nodes treated with saline had no lacZ staining.


Imaging of lymph node micrometastases using an oncolytic herpes virus and [F]FEAU PET.

Brader P, Kelly K, Gang S, Shah JP, Wong RJ, Hricak H, Blasberg RG, Fong Y, Gil Z - PLoS ONE (2009)

Histologic analysis of lymph nodes after imaging showing metastatic and normal lymph nodes from mice injected with NV1023.(A) LacZ staining (blue) shows diffuse β-galactosidase transgene expression adjacent to metastatic B16-F10 melanoma cells (black cells, scale bar 30 µm). The white arrow indicates the area of micrometastases. (B) High magnification of the area in (A) indicated by the arrow showing diffuse LacZ staining in the area of metastases (scale bar 10 µm). (C) High magnification of a positive lymph node showing non-specific LacZ stain in an area devoid of melanoma cells. (D) Low magnification of a normal lymph node from an animal treated with NV1023. Only a non-specific LacZ staining is seen (scale bar 130 µm).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2651472&req=5

pone-0004789-g004: Histologic analysis of lymph nodes after imaging showing metastatic and normal lymph nodes from mice injected with NV1023.(A) LacZ staining (blue) shows diffuse β-galactosidase transgene expression adjacent to metastatic B16-F10 melanoma cells (black cells, scale bar 30 µm). The white arrow indicates the area of micrometastases. (B) High magnification of the area in (A) indicated by the arrow showing diffuse LacZ staining in the area of metastases (scale bar 10 µm). (C) High magnification of a positive lymph node showing non-specific LacZ stain in an area devoid of melanoma cells. (D) Low magnification of a normal lymph node from an animal treated with NV1023. Only a non-specific LacZ staining is seen (scale bar 130 µm).
Mentions: Histopathologic analysis was used to define positive (with melanoma metastases) and negative (no tumor cells) lymph nodes. The presence of NV1023 in sentinel lymph nodes with melanoma micrometastases was verified based on expression of the lacZ transgene. LacZ staining after NV1023 infection in vitro revealed cytoplasmatic expression of β-galactosidase (Figure S1). However melanoma metastatic cells in lymph nodes had dark pigmented cytoplasm, and it was difficult to see the light blue lacZ staining in the cells. Yet, by analyzing whole specimens of lymph nodes with metastases, we found diffuse accumulation of lacZ staining only in areas with metastatic melanoma cells (Fig 4A–C). In contrast, when the same staining was performed on normal lymph nodes of mice injected with NV1023, we noticed only light and non-specific staining of lacZ (Fig 4D). Similarly, positive lymph nodes treated with saline had no lacZ staining.

Bottom Line: Presence of virus-infected tumor cells was successfully imaged with [(18)F]FEAU-PET, that identified 8 out of 8 tumor-positive nodes.There was no overlap between radioactivity levels (lymph node to surrounding tissue ratio) of tumor-positive and tumor-negative lymph nodes.A new approach for imaging SLN metastases using NV1023 and [(18)F]FEAU-PET was successful in a murine model.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America.

ABSTRACT

Background: In patients with melanoma, knowledge of regional lymph node status provides important information on outlook. Since lymph node status can influence treatment, surgery for sentinel lymph node (SLN) biopsy became a standard staging procedure for these patients. Current imaging modalities have a limited sensitivity for detection of micrometastases in lymph nodes and, therefore, there is a need for a better technique that can accurately identify occult SLN metastases.

Methodology/principal findings: B16-F10 murine melanoma cells were infected with replication-competent herpes simplex virus (HSV) NV1023. The presence of tumor-targeting and reporter-expressing virus was assessed by [(18)F]-2'-fluoro-2'-deoxy-1-beta-D-beta-arabinofuranosyl-5-ethyluracil ([(18)F]FEAU) positron emission tomography (PET) and confirmed by histochemical assays. An animal foot pad model of melanoma lymph node metastasis was established. Mice received intratumoral injections of NV1023, and 48 hours later were imaged after i.v. injection of [(18)F]FEAU. NV1023 successfully infected and provided high levels of lacZ transgene expression in melanoma cells. Intratumoral injection of NV1023 resulted in viral trafficking to melanoma cells that had metastasized to popliteal and inguinal lymph nodes. Presence of virus-infected tumor cells was successfully imaged with [(18)F]FEAU-PET, that identified 8 out of 8 tumor-positive nodes. There was no overlap between radioactivity levels (lymph node to surrounding tissue ratio) of tumor-positive and tumor-negative lymph nodes.

Conclusion/significance: A new approach for imaging SLN metastases using NV1023 and [(18)F]FEAU-PET was successful in a murine model. Similar studies could be translated to the clinic and improve the staging and management of patients with melanoma.

Show MeSH
Related in: MedlinePlus