Anaplastic thyroid cancer

Cetuximab and irinotecan interact synergistically to inhibit the growth of orthotopic anaplastic thyroid carcinoma xenografts in nude mice

PURPOSE

Anaplastic thyroid carcinoma (ATC) remains one of the most lethal known human cancers. Targeted molecular therapy with cetuximab, a monoclonal antibody against epidermal growth factor receptor, offers new treatment potentials for patient with ATC. Cetuximab has also been reported to have synergistic effects when combined with irinotecan, a topoisomerase inhibitor. Therefore, we hypothesized that cetuximab and irinotecan would be effective in inhibiting the growth and progression of ATC in a murine orthotopic model.

EXPERIMENTAL DESIGN

The in vitro antiproliferative effects of cetuximab and irinotecan on ATC cell line ARO were examined. We also studied the in vivo effects of cetuximab and irinotecan on the growth, invasion, and metastasis of orthotopic ATC tumors in nude mice. The in vivo antitumor efficacy of cetuximab/irinotecan combination was also compared with that of doxorubicin.

RESULTS

Cetuximab alone did not show any antiproliferative or proapoptotic effect on this cell line. However, when combined with irinotecan, cetuximab potentiated the in vitro antiproliferative and proapoptotic effect of irinotecan. Cetuximab, irinotecan, and cetuximab/irinotecan combination resulted in 77%, 79%, and 93% in vivo inhibition of tumor growth, respectively. Incidences of lymph node metastasis, laryngeal invasion, and tumor microvessel density were also significantly decreased in these treatment groups. Furthermore, the cetuximab/irinotecan combination was significantly more effective than doxorubicin in inhibiting the growth of orthotopic ATC xenografts.

CONCLUSIONS

Combination therapy with cetuximab/irinotecan inhibits the growth and progression of orthotopic ATC xenografts in nude mice. Given the lack of curative options for patients with ATC, combination therapy with cetuximab and irinotecan treatment warrants further study.

Anaplastic Thyroid Carcinoma: Biology, Pathogenesis, Prognostic Factors, and Treatment Approaches

BACKGROUND

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive solid tumors known to affect humans and carries a dismal prognosis. Our primary aim was to review its epidemiology, biology, risk factors, and prognostic indicators. We also reviewed the individual and combined roles of surgery, radiotherapy, chemotherapy, and newer therapeutic options in the management of ATC.

METHODS

An extensive literature review was conducted to include all published reports on ATC. The changing trends in the management of anaplastic thyroid cancer were analyzed to summarize the current practice of management of ATC.

RESULTS

Although ATC is rare, there has been a decline in its incidence worldwide. ATC accounts for more than half of the 1200 deaths per year attributed to thyroid cancer. Long-term survivors are rare, with >75% and 50% of patients harboring cervical nodal disease and metastatic disease, respectively, at presentation. ATC can arise de novo or from preexisting well-differentiated thyroid cancer. Surgical management has shifted from tracheostomy only for palliation to curative resection when possible. Tracheostomy is performed for impending obstruction rather than for prophylaxis. Radiotherapy has evolved from postoperative administration only to preoperative treatment, combining preoperative and postoperative treatment and using higher doses, along with hyperfractionating and accelerating dose schedules. Chemotherapy has changed from monotherapy to combination therapy, and newer drugs such as paclitaxel show promise. Similarly, novel angiogenesis-inhibiting agents are currently being used, with early reports of some benefit.

CONCLUSIONS

Despite multimodality approaches, ATC still carries a dismal prognosis. This should provoke innovative strategies beyond conventional methods to tackle this uniformly lethal disease.

Prognostic factors of anaplastic thyroid carcinoma

BACKGROUND AND PURPOSE

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive malignancies. We tried to elucidate the possible prognostic factors.

METHODS

A retrospective review was conducted of ATC patients in National Taiwan University Hospital from 1978 to 2003. Their demographic characteristics, clinical presentations, laboratory data and treatment modalities were reviewed. Possible prognostic factors for survival were evaluated.

RESULTS

Forty-five patients (14 males and 31 females) of mean age 61.9 +/- 12.6 yr were included in this study. The median survival time was 94 days (range 6 to 776 days). The overall survival rate was 27% at 6 months and 10% at 1 yr. Thirty-two patients receiving intervention regimens had a median survival of 106 days, while 13 patients receiving palliative therapy had a median survival of 39 days. The difference in survival is statistically significant (logrank test, p = 0.017). Adjusted with sex and age, increment in white blood cell count (per 10(9)/l) and serum albumin (per 1.0 g/l) had a hazard ratio of 1.12 (Cox regression, p < 0.001) and 0.92 (p = 0.041), respectively. Patients with leukocytosis [white blood cell (WBC) count > 10(10)/l] or hypoalbuminemia (serum albumin < 35 g/l) had significant shorter survival than patients without leukocytosis or hypoalbuminemia (logrank test p = 0.008 and p = 0.032, respectively). Patients with serum T4 levels lower than 64.35 nmol/l had significantly shorter survival than patients without hypothyroxinemia (median survival 24 vs 128 days, logrank test, p = 0.004).

CONCLUSIONS

ATC is an aggressive malignancy. Leukocytosis, hypoalbuminemia and hypothyroxinemia indicated poor prognosis. Survival time might be prolonged if intervention treatment is tolerable.

Clinical outcome of anaplastic thyroid carcinoma treated with radiotherapy of once- and twice-daily fractionation regimens

BACKGROUND

The purpose was to assess local control, survival, and toxicity after radiotherapy in patients with anaplastic thyroid carcinoma, and to compare clinical outcomes between once-daily and twice-daily fractionation regimens.

METHODS

A retrospective review of patients with anaplastic thyroid carcinoma (n = 47) who underwent external beam radiotherapy from 1983 to 2004 was conducted. Twenty-three patients underwent radical radiotherapy with a radiation dose > 40 Gy, and 24 patients underwent palliative radiotherapy with a dose < or = 40 Gy. Of radical radiotherapy, radiation was given with once-daily (14 patients) or twice-daily fractionation (9 patients; 1.5 Gy per fraction) to a total dose of 45-66 Gy. Most patients (37 patients; 78.7%) were followed to death.

RESULTS

The 6-month local progression-free rate in patients who underwent radical radiotherapy was 94.1%, significantly higher compared with palliative radiotherapy (64.6%; P = .02). The median actuarial overall survival was greater in patients with radical radiotherapy (11.1 months) compared with palliative radiotherapy (3.2 months; P < .0001). The median overall survival in patients with twice-daily fractionation (13.6 months) was 3.3 months longer than patients treated with once-daily fractionation (10.3 months), but the difference was not statistically significant (P = .3). For patients treated with twice-daily fractionation, 3 patients had Grade 3 acute skin toxicity, and no patient had Grade 3 or higher esophageal toxicity.

CONCLUSIONS

Radiotherapy can result in local control of anaplastic thyroid carcinoma. A twice-daily fractionation regimen is well tolerated and has a trend to longer survival, which deserves a larger study.

Growth inhibition of orthotopic anaplastic thyroid carcinoma xenografts in nude mice by PTK787/ZK222584 and CPT-11

BACKGROUND

A preclinical evaluation of CPT-1 (Camptosar, irinotecan) and PTK787/ZK222584, a vascular endothelial growth factor receptor (VEGFR-2) tyrosine kinase inhibitor, as therapeutic agents against anaplastic thyroid carcinoma (ATC) was performed in vitro and in an orthotopic model of ATC in nude mice.

METHODS

The cytotoxic and cytostatic effects of CPT-11 on ATC cell lines were evaluated. The antitumor effects of CPT-11 in combination with PTK787/ZK222584 on orthotopic ATC xenografts in nude mice were also studied.

RESULTS

CPT-11 demonstrated significant antiproliferative effects on ATC cell lines. In vivo, PTK787/ZK222584, CPT-11, and the two agents together produced 61%, 82%, and 89% decrease in tumor growth, respectively. The differences in tumor volume between CPT-11 and CPT-11 + PTK787/ZK222584 groups were not statistically significant. PTK787/ZK222584 inhibited the phosphorylation of VEGFR-2 on tumor endothelium and decrease the tumor microvessel density.

CONCLUSIONS

The camptothecin class of chemotherapeutic agents and antiangiogenic agents such as PTK787/ZK222584 warrant further study as novel therapeutic agents against ATC.

Expression of Aurora kinases in human thyroid carcinoma cell lines and tissues

The Aurora kinases are involved in the regulation of cell cycle progression, and alterations in their expression have been shown to associate with cell malignant transformation. In the present study, we demonstrated that human thyrocytes express all 3 Aurora kinases (A, B and C) at both protein and mRNA level and this expression is cell cycle-regulated. An increase in the protein level of the 3 kinases was found, with respect to normal human thyrocytes (HTU5), in the human cell lines derived from follicular (FTC-133), papillary (B-CPAP) and anaplastic (8305C) thyroid carcinomas, but not in cells derived from a follicular adenoma (HTU42). These observations were mirrored in RT-PCR experiments for Aurora-A and B. In contrast, Aurora-C mRNA levels were not significantly different among the different cell types analyzed, suggesting that posttranscriptional mechanism(s) modulate its expression. The expression at the protein level of all 3 Aurora kinases was significantly higher in 3 thyroid papillary carcinomas with respect to normal matched tissues obtained from the same patients. Similar modifications, at the mRNA level, could be observed in 7 papillary carcinoma tissues for Aurora-A and B, but not for Aurora-C. In conclusion, we demonstrated that normal human thyrocytes express all 3 members of the Aurora kinase family, and their expression is amplified in malignant thyroid cell lines and tissues. These results suggest that the Aurora kinases may play a relevant role in malignant thyroid cancers, and may represent a putative therapeutic target for thyroid neoplasms.

Anaplastic thyroid carcinoma: a therapeutic dilemma

Anaplastic thyroid carcinoma (ATC) is one of the most malignant human neoplasms and has a grave prognosis. This study gives an update on our experience with this unusual neoplasm, with specific focus on the response to various treatment modalities. Forty-seven patients with histologically proven ATCs were enrolled (19 men, 28 women; mean age, 62.8 years). This number represents 1.5% among a total of 3,088 thyroid cancers treated between 1977 and 2002. The mean tumor diameter was 8.8 cm, and 22 patients had distant metastasis. Extrathyroidal extension was seen in 26 (89.7%) of the cases that underwent surgery. Treatment modalities adopted could be classified into 5 groups: Group 1, biopsy only; Group 2, biopsy and chemoradiotherapy; Group 3, debulking only; Group 4, debulking and chemoradiotherapy; Group 5, complete excision and chemoradiotherapy. Survival was calculated from the time of diagnosis, and comparisons of survival were done by log-rank analysis. The mean survival was 4.3 months (range, 1.0-21 months). The mean survival based on treatment modalities were as follows: Group 1 (n = 10), 2.1 months, Group 2 (n = 8); 3.6 months; Group 3 (n = 7), 3.0 months; Group 4 (n = 14), 3.5 months, Group 5 (n = 8), 9.4 months. There was no significant difference in survival time between the various types of treatment modalities. Even though a small improvement in survival was observed with complete excision and aggressive multimodality therapy, nearly all ATCs remain unresponsive to ongoing treatment modalities and as such, present a therapeutic dilemma. A more effective treatment regimen should be sought in order to improve survival.

Targeted molecular therapy of anaplastic thyroid carcinoma with AEE788

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human malignancies with a mean survival of only 6 months. The poor prognosis of patients with ATC reflects the current lack of curative therapeutic options and the need for development of novel therapeutic strategies. In this study, we report the results of a preclinical study of AEE788, a dual inhibitor of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor (VEGFR) tyrosine kinases, against ATC. AEE788 was able to inhibit the proliferation and induce apoptosis of ATC cell lines in vitro. Administration of AEE788, alone and in combination with paclitaxel, to athymic nude mice bearing s.c. ATC xenografts inhibited the growth of ATC xenografts by 44% and 69%, respectively, compared with the control group. Furthermore, tumors from mice treated with AEE788, alone and in combination with paclitaxel, showed increase in apoptosis of tumor cells by approximately 6- and 8-fold, respectively, compared with the control group. The microvessel density within the ATC xenografts was decreased by >80% in the mice treated with AEE788 alone and in combination with paclitaxel compared with the control group. Lastly, immunofluorescence microscopy showed the inhibition of EGFR autophosphorylation on the tumor cells as well as the inhibition of VEGFR-2 autophosphorylation on tumor endothelium. Considering the fact that curative options seldom exist for patients with ATC, concurrent inhibition of EGFR and VEGFR tyrosine kinases seems to be a valid and promising anticancer strategy for these patients.

An orthotopic model of anaplastic thyroid carcinoma in athymic nude mice

PURPOSE

To develop an orthotopic model of anaplastic thyroid carcinoma (ATC) in athymic nude mice.

EXPERIMENTAL DESIGN

Various thyroid carcinoma cell lines were injected into the thyroid gland of athymic nude mice to determine whether such injection was technically feasible. ATC cells were then injected into the thyroid gland or the subcutis of nude mice at various concentrations, and the mice were then followed for tumor development. The tumors were examined histopathologically for local invasion or regional or distant metastasis.

RESULTS

Injection of tumor cells into the thyroid glands of nude mice was technically feasible and resulted in the formation of thyroid tumors. The ATC cell line DRO showed significantly higher tumorigenicity in the thyroid gland than in the subcutis. In contrast, oral squamous cell carcinoma cell line TU167 shows no significantly higher tumorigenicity in the thyroid gland than in the subcutis. ATC tumors established in the thyroid gland also produced symptomatic compression of the esophagus and the trachea. Local invasion of the larynx and trachea was as well as high rates of pulmonary metastasis were also observed. Immunohistochemical staining showed higher microvessel density as well as higher expression of vascular endothelial growth factor and interleukin-8 in the orthotopic thyroid tumors than in ectopic tumors.

CONCLUSION

An orthotopic model of ATC in athymic nude mice was developed that closely recapitulates the clinical findings of human ATC. This model should facilitate the understanding of the pathogenesis of ATC and aid in the development of novel therapies against ATC.

Anaplastic thyroid carcinoma

BACKGROUND

Anaplastic thyroid carcinoma (ATC) is rare but is one of the most aggressive human malignancies. Several prognostic factors have been observed in patients with ATC, and some experts advocate aggressive multimodal therapy in selected patients. However, it is unclear whether such an approach significantly improves survival. The authors analyzed prognostic factors and treatment outcomes in patients with ATC reported in the National Cancer Institute's Surveillance, Epidemiology, and End Results data base.

METHODS

The cohort consisted of 516 patients with ATC reported to 12 population-based cancer registries between 1973 and 2000. Demographic, pathologic, and treatment data were used for univariate and multivariate survival analyses.

RESULTS

The mean patient age at diagnosis was 71.3 years, and there were 171 men and 345 women. Eight percent of patients had intrathyroidal tumors, 38% had extrathyroidal tumors and/or lymph node invasion, and 43% of patients had distant metastasis. The average tumor size was 6.4 cm (range, 1-15 cm). Sixty-four percent of patients underwent surgical resection of their primary tumor, and 63% received external beam radiotherapy. The overall cause-specific mortality rate was 68.4% at 6 months and 80.7% at 12 months. Univariate analysis showed that age < 60 years, female gender, intrathyroidal tumor, external beam radiotherapy, surgical resection, and combined surgical resection of tumor and radiotherapy were associated with a lower cause-specific mortality. On multivariate analysis, only age < 60 years, an intrathyroidal tumor, and the combined use of surgical and external beam radiation therapy were identified as independent predictors of lower cause-specific mortality.

CONCLUSIONS

Although most patients with ATC had an extremely poor prognosis, patients < 60 years old with intrathyroidal tumors survived longer. Surgical resection with external beam radiotherapy for ATC was associated with lower cause-specific mortality.

Anaplastic thyroid cancer and hyperthyroidism

We report a rare case of thyrotoxicosis in a patient with anaplastic thyroid cancer. A 65-yr-old male presented with a 2-d history of rapidly enlarging neck mass and back pain. Physical examination revealed a large, hard thyroid mass and resting tachycardia. He did not have any symptoms suggestive of airway compression at presentation. Thyroid hormone levels were consistent with a hyperthyroid state. CT scan of the neck and thorax showed a heterogeneous mass replacing the thyroid, bilateral pulmonary nodules, and a metastasis with pathological fracture at the level of T-8. Technetium-pertechnetate scan failed to show any uptake in the region of the thyroid. Fine needle aspiration of the thyroid revealed anaplastic thyroid cancer. The patient was started on steroids and radiation therapy of his spine lesion. Brief surgical exploration of the thyroid revealed extensive local infiltration of adjacent neck tissues and marked tumor necrosis. Immunohistochemical stains of the tumor were positive for p53, thyroglobulin, and thyroid transcription factor-1. The tumor had an extremely aggressive course and the patient died of asphyxiation from severe airway compromise 11 d after his initial presentation.

Biodistribution of p-borophenylalanine (BPA) in dogs with spontaneous undifferentiated thyroid carcinoma (UTC)

Human undifferentiated thyroid carcinoma (UTC) is a very aggressive tumor which lacks an adequate treatment. The UTC human cell line ARO has a selective uptake of BPA in vitro and after transplanting into nude mice. Applications of boron neutron capture therapy (BNCT) to mice showed a 100% control of growth and a 50% histological cure of tumors with an initial volume of 50 mm(3) or less. As a further step towards the potential application in humans we have performed the present studies. Four dogs with diagnosis of spontaneous UTC were studied. A BPA-fructose solution was infused during 60 min and dogs were submitted to thyroidectomy. Samples of blood and from different areas of the tumors (and in one dog from normal thyroid) were obtained and the boron was determined by ICP-OES. Selective BPA uptake by the tumor was found in all animals, the tumor/blood ratios ranged between 2.02 and 3.76, while the tumor/normal thyroid ratio was 6.78. Individual samples had tumor/blood ratios between 8.36 and 0.33. These ratios were related to the two histological patterns observed: homogeneous and heterogeneous tumors. We confirm the selective uptake of BPA by spontaneous UTC in dogs and plan to apply BNCT in the future.

BRAF mutations in anaplastic thyroid carcinoma: implications for tumor origin, diagnosis and treatment

Anaplastic thyroid carcinoma is a highly aggressive neoplasm. Affected patients typically present with advanced disease where there is little hope for cure using conventional therapeutic modalities. Understanding the genetic alterations underlying the development of anaplastic thyroid carcinoma, such as mutational activation of BRAF, could help clarify its relationship with well-differentiated forms of thyroid carcinoma (ie follicular and papillary carcinoma) and could help select patients most likely to benefit from novel therapeutic strategies targeting BRAF. We tested 16 anaplastic thyroid carcinomas for the thymine (T) --> adenine (A) missense mutation at nucleotide 1796 in the BRAF gene using a newly developed assay that employs a novel primer extension method (Mutector assay). Seven of these anaplastic thyroid carcinomas arose in association with a well-differentiated thyroid carcinoma, and these were also evaluated. The 1796T --> A mutation was detected in eight (50%) of the anaplastic thyroid carcinomas, in four of five (80%) associated papillary thyroid carcinomas, and in zero of two (0%) associated follicular carcinomas. In all seven cases where anaplastic thyroid carcinoma arose in association with a well-differentiated thyroid carcinoma, BRAF status in the two components was concordant. Like papillary thyroid carcinoma, a significant percentage of anaplastic thyroid carcinomas also harbor BRAF mutations. Indeed, when papillary thyroid carcinoma and anaplastic thyroid carcinoma occur together, they consistently share the same BRAF profile, supporting the notion that many anaplastic thyroid carcinomas actually represent progressive malignant degeneration of a pre-existing well-differentiated thyroid carcinoma. The high frequency of BRAF mutations in a tumor that is generally regarded as uniformly fatal justifies evaluation of the potential benefits of anti-BRAF therapy for patients with anaplastic thyroid carcinoma.

Expression of matrix metalloproteinases and their specific inhibitors in normal and different human thyroid tumor cell lines

In the present study we investigated, by means of zymography and reverse transcription-polymerase chain reaction (RT-PCR), the expression of different matrix metalloproteinases (MMPs) and of the specific tissue inhibitor of metalloproteinases [TIMPs] in human cell lines derived from normal thyrocytes (HTU5), follicular adenoma (HTU42), and follicular (FTC-133), papillary (B-CPAP), and anaplastic (CAL-62, 8305C) thyroid carcinomas. We demonstrated that normal thyrocytes constitutively express MMP-1, MMP-2, MMP-10, MMP-14, and TIMP-1, TIMP-2, TIMP-3, and TIMP-4, and this pattern of expression is profoundly modified in all thyroid tumor-derived cell lines. Analysis of the gelatinolytic activity in the different cell supernatants showed that the expressions of MMP-2 and MMP-9 are, respectively, increased or induced in all the neoplastic cell lines, except in CAL-62. Caseinolytic activity was found only in the supernatants of the 8305C and B-CPAP cells. Using RTPCR analysis we detected an increased expression of MMP-1 in cell lines derived from papillary and from one (8305C) of the two anaplastic carcinomas. MMP-13 mRNA was expressed only in the 8305C, FTC-133, and BCPAP cells. Among stromelysins, MMP-3 mRNA could not be detected in any cell line, while MMP-10 mRNA was expressed in all of them, although at variable levels. MMP-11 mRNA was absent in normal and follicular adenoma derived thyrocytes and induced in all carcinoma cell types. The expression of MMP-14 (MT1-MMP) mRNA was found significantly increased in all thyroid tumor cell lines with respect to HTU5 and HTU42 cells. The expression of TIMP-1 and TIMP-2 mRNAs was maintained in all cell lines tested, while that of TIMP-3 was lost in both anaplastic carcinoma cell lines and that of TIMP-4 was absent in the CAL-62. In conclusion, our data demonstrated a differential expression of MMPs and TIMPs in different thyroid tumor cell types with respect to normal thyrocytes. In particular, the induction of MMP-11 in all thyroid-derived carcinoma cell lines studied and of MMP-13 in all but one may represent, if confirmed in other thyroid tumor-derived cell lines and in thyroid tumor tissues, a new marker of thyrocyte transformation.

Cytotoxic effects of gemcitabine-loaded liposomes in human anaplastic thyroid carcinoma cells

BACKGROUND

Identification of effective systemic antineoplastic drugs against anaplastic thyroid carcinomas has particularly important implications. In fact, the efficacy of the chemotherapeutic agents presently used in these tumours, is strongly limited by their low therapeutic index.

METHODS

In this study gemcitabine was entrapped within a pegylated liposomal delivery system to improve the drug antitumoral activity, thus exploiting the possibility to reduce doses to be administered in cancer therapy. The cytotoxic effects of free or liposome-entrapped gemcitabine was evaluated against a human thyroid tumour cell line. ARO cells, derived from a thyroid anaplastic carcinoma, were exposed to different concentrations of the drug. Liposomes formulations were made up of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/cholesterol/1,2-distearoyl-sn-glycero-3-phosphoethanolamine-MPEG (8:3:1 molar ratio). Cell viability was assessed by both trypan bleu dye exclusion assay and fluorimetric analysis of cell DNA content.

RESULTS

A cytotoxic effect of free gemcitabine was present only after 72 h incubation (ARO cell mortality increased of approximately 4 fold over control at 1 microM, 7 fold at 100 microM). When gemcitabine was encapsulated in liposomes, a significant effect was observed by using lower concentrations of the drug (increased cell mortality of 2.4 fold vs. control at 0.3 microM) and earlier exposure time (24 h).

CONCLUSION

These findings show that, in vitro against human thyroid cancer cells, the gemcitabine incorporation within liposomes enhances the drug cytotoxic effect with respect to free gemcitabine, thus suggesting a more effective drug uptake inside the cells. This may allow the use of new formulations with lower dosages (side effect free) for the treatment of anaplastic human thyroid tumours.

Molecular evidence of anaplastic transformation in coexisting well-differentiated and anaplastic carcinomas of the thyroid

Anaplastic thyroid cancer is a rare but nearly universally fatal tumor. Epidemiologic data suggest that many anaplastic thyroid carcinomas arise from transformation of preexisting or coexisting well-differentiated thyroid carcinomas. At the molecular level, the mutations responsible for the anaplastic transformation are incompletely understood, although the mutational events are thought to involve tumor suppressor genes. To examine transformation from a well-differentiated thyroid carcinoma to anaplastic carcinoma, we studied coexisting well-differentiated (Hürthle cell and papillary carcinoma) and anaplastic tumors with a molecular genotyping panel of tumor suppressor genes associated with thyroid neoplasia. The patterns of allelic loss in our results showed that the majority of cases have a core of conserved mutations in the two morphologically distinct areas and substantial increases in mutation rates in the anaplastic components.

Treatment of aggressive thyroid cancer with an oncolytic herpes virus

Although many thyroid cancers carry a favorable prognosis, there is a subgroup of patients with more aggressive histologies. Current therapies offer no significant survival benefit to patients with anaplastic thyroid carcinomas, which are considered fatal. Oncolytic herpes simplex viruses (HSVs) have potent antitumor effects against a variety of human malignancies. We assessed the activity of a replication-competent, attenuated, oncolytic HSV (NV1023) against 7 different thyroid cancers, including one papillary (NPA-187), one follicular (WRO82-1), one medullary (DRO81-1) and 4 anaplastic (DRO90-1, ARO, KAT-4C and KAT-18) cell lines. Only the follicular WRO82-1 line was resistant to NV1023 infection and cell lysis at a concentration of 5 viral pfu per cell (MOI 5). All other cell lines at MOI 5 demonstrated >95% infection in vitro at day 2 by X-gal staining and >88% cell death at day 4 by cytotoxicity assays. Even at MOI 0.1, 4 of these lines displayed complete cell death by day 7. Viral proliferation assays revealed that all of the nonfollicular cell lines supported logarithmic viral replication. Flank tumors of NPA-187, DRO81-1, DRO90-1 and ARO in athymic nude mice were treated with NV1023 (2 x 10(7) pfu). All NPA-187 tumors completely regressed following a single dose. DRO81-1 tumors demonstrated partial response with a single dose and significant improvement with 3 serial doses. ARO and DRO90-1 tumors showed a significant response following either single injection (54 +/- 22 and 292 +/- 138 mm3, respectively) or 3 serial injections (33 +/- 14 and 241 +/- 68 mm3, respectively) compared to saline injections (472 +/- 193 and 1,257 +/- 204 mm3, respectively) at day 20. These data suggest that herpes oncolytic therapy may be effective for the treatment of aggressive thyroid carcinomas and merits further investigation.