Radioiodine (RAI) in combination with durvalumab for recurrent/metastatic thyroid cancers

6587

Background: Immune checkpoint blockade (ICB) has limited efficacy for radioiodine-refractory thyroid cancer. The high incidence of autoimmune thyroid disease and ICB-induced hypothyroidism suggests that loss of T cell tolerance to thyroid protein epitopes is common and can be activated by ICB to induce immune responses. We hypothesize that RAI can enhance presentation of thyroid protein immunogens and putative neoantigens in thyroid cancers to amplify the effectiveness of ICB. We studied the safety and efficacy of RAI plus the anti-PD-L1 agent durvalumab (durva) in recurrent/metastatic (R/M) patients (pts). Methods: Pts. had at least one RAI-avid tumor on the most recent RAI scan or one tumor on FDG PET with an SUVmax < 10. RECIST measurable disease was required. Any number of prior therapies was allowed. Pts were treated with durva 1500 mg IV every 4 weeks with recombinant human TSH (rhTSH)-stimulated RAI (100 mCi) administered in Cycle 1. Treatment beyond progression was allowed. The primary objective was to assess safety. Durva related dose limiting toxicities (DLTs) were monitored for 6 weeks after the first dose. Since no durva DLTs were observed in the first 6 pts, per protocol rules the trial accrued 11 pts total. Secondary objectives were assessing best overall response (BOR) per RECIST and progression-free survival (PFS). Results: 11 pts (7 female) were enrolled. Eight had prior drug therapy. No DLTs or > Grade 3 durva related adverse events (AEs) were observed. The most common non-laboratory AEs (regardless of attribution) were cough (7), hypertension (7), pain (6), edema (5), and fatigue/nausea/diarrhea/arthralgia/dry skin/dyspnea/edema (4 each). As of 2/6/20, 2 had partial response, 7 stable disease, and 2 progression of disease as BOR. Six pts had tumor regression. Four pts received treatment for > 6 months. Six are still on treatment. Analyses of research biopsies (bxs) (8 had pre-treatment bxs, 6 had an additional on-treatment bx) will be presented. Conclusions: Durva plus RAI is safe and well tolerated. The preliminary efficacy signal in this small cohort is promising. Understanding how RAI plus PD-L1 targeting impacts the tumor immune microenvironment may guide how RAI should be evaluated in future ICB trials. Clinical trial information: NCT03215095 .

Genomic and Transcriptomic Characterization of Papillary Microcarcinomas With Lateral Neck Lymph Node Metastases

CONTEXT

Most papillary microcarcinomas (PMCs) are indolent and subclinical. However, as many as 10% can present with clinically significant nodal metastases.

OBJECTIVE AND DESIGN

Characterization of the genomic and transcriptomic landscape of PMCs presenting with or without clinically important lymph node metastases.

SUBJECTS AND SAMPLES

Formalin-fixed paraffin-embedded PMC samples from 40 patients with lateral neck nodal metastases (pN1b) and 71 patients with PMC with documented absence of nodal disease (pN0).

OUTCOME MEASURES

To interrogate DNA alterations in 410 genes commonly mutated in cancer and test for differential gene expression using a custom NanoString panel of 248 genes selected primarily based on their association with tumor size and nodal disease in the papillary thyroid cancer TCGA project.

RESULTS

The genomic landscapes of PMC with or without pN1b were similar. Mutations in TERT promoter (3%) and TP53 (1%) were exclusive to N1b cases. Transcriptomic analysis revealed differential expression of 43 genes in PMCs with pN1b compared with pN0. A random forest machine learning-based molecular classifier developed to predict regional lymph node metastasis demonstrated a negative predictive value of 0.98 and a positive predictive value of 0.72 at a prevalence of 10% pN1b disease.

CONCLUSIONS

The genomic landscape of tumors with pN1b and pN0 disease was similar, whereas 43 genes selected primarily by mining the TCGA RNAseq data were differentially expressed. This bioinformatics-driven approach to the development of a custom transcriptomic assay provides a basis for a molecular classifier for pN1b risk stratification in PMC.

Outcome and molecular characteristics of non-invasive encapsulated follicular variant of papillary thyroid carcinoma with oncocytic features

PURPOSE

In 2016, non-invasive encapsulated follicular variant of papillary thyroid carcinoma (NI-EFVPTC) was renamed as noninvasive thyroid follicular neoplasm with papillary-like nuclear features (NIFTP). However, as the study cohort did not mention tumors with oncocytic features, such lesions are still labeled by some as FVPTC. It is therefore crucial to evaluate the outcome and molecular profile of oncocytic NI-EFVPTC.

METHODS

A multi-institutional clinico-pathologic review was conducted to select 61 patients having oncocytic NI-EFVPTC. A detailed molecular profile was carried out in 15 patients.

RESULTS

Oncocytic NI-EFVPTCs predominantly affected women in their 50s. There was no distant metastasis, lymph node metastases, or structural recurrence in the entire cohort. Among patients with ≥5 years of FU, all 33 individuals did not recur with a median FU of 10.2 years. Oncocytic NI-EFVPTC commonly had RAS (33%) mutations, a high frequency of mitochondrial DNA mutations (67%) and multiple chromosomal gains/losses (53%). No fusion genes were detected.

CONCLUSIONS

Oncocytic NI-EFVPTC, when stringently selected for, lacks metastasis at presentation and follows an extremely indolent clinical course, even when treated conservatively with lobectomy alone without RAI therapy. These tumors share a similar mutational profile as NIFTP, FVPTC, and follicular neoplasm and are predominantly RAS-related. Like Hurthle cell neoplasms, they harbor a high frequency of mitochondrial DNA mutations, which contribute to the oncocytic cytomorphology. However, they lack the widespread chromosomal alterations observed in Hurthle cell carcinoma. Consideration should be given to include oncocytic NI-EFVPTCs as NIFTP in order to avoid overtreatment of these highly indolent tumors.

Lysyl Oxidase Is a Key Player in BRAF/MAPK Pathway-Driven Thyroid Cancer Aggressiveness

BACKGROUND

The BRAF^V600E mutation is the most common somatic mutation in thyroid cancer. The mechanism associated with BRAF-mutant tumor aggressiveness remains unclear. Lysyl oxidase (LOX) is highly expressed in aggressive thyroid cancers, and involved in cancer metastasis. The objective was to determine whether LOX mediates the effect of the activated MAPK pathway in thyroid cancer.

METHODS

The prognostic value of LOX and its association with mutated BRAF was analyzed in The Cancer Genome Atlas and an independent cohort. Inhibition of mutant BRAF and the MAPK pathway, and overexpression of mutant BRAF and mouse models of BRAF^V600E were used to test the effect on LOX expression.

RESULTS

In The Cancer Genome Atlas cohort, LOX expression was higher in BRAF-mutant tumors compared to wild-type tumors (p < 0.0001). Patients with BRAF-mutant tumors with high LOX expression had a shorter disease-free survival (p = 0.03) compared to patients with a BRAF mutation and the low LOX group. In the independent cohort, a significant positive correlation between LOX and percentage of BRAF mutated cells was found. The independent cohort confirmed high LOX expression to be associated with a shorter disease-free survival (p = 0.01). Inhibition of BRAF^V600E and MEK decreased LOX expression. Conversely, overexpression of mutant BRAF increased LOX expression. The mice with thyroid-specific expression of BRAF^V600E showed strong LOX and p-ERK expression in tumor tissue. Inhibition of BRAF^V600E in transgenic and orthotopic mouse models significantly reduced the tumor burden as well as LOX and p-ERK expression.

CONCLUSIONS

The data suggest that BRAF^V600E tumors with high LOX expression are associated with more aggressive disease. The biological underpinnings of the clinical findings were confirmed by showing that BRAF and the MAPK pathway regulate LOX expression.

Abstract 4291: Hras versus Braf activation determines follicular versus papillary thyroid cancer development

Thyroid cancer is the most common endocrine malignancy, and incidences are rising. MAP kinase (MAPK) signaling has been implicated in playing a critical role in the initiation and maintenance of thyroid cancer, as evidenced by the high incidence of non-overlapping mutations of the genes encoding RET and TRK, as well as of NRAS, HRAS, KRAS and BRAF. Follicular thyroid cancer (FTC) is commonly associated with mutations of the RAS family of oncoproteins, while papillary thyroid cancer (PTC) is often associated with mutations in BRAF. To determine whether mode of MAPK activation played a role in thyroid cancer development in mice, we generated HrasG12V and BrafV600E knock-in models. We report that a thyroid specific knock-in of HrasG12V and Pten inactivation leads to the development of FTCs and poorly differentiated thyroid cancer (PDTCs) by 47-52 weeks of age in HrasG12V/Ptenhom/TPO-cre mice. In stark contrast, mice with a thyroid specific knock-in of BrafV600E and loss of Pten (BrafV600E/Ptenhom/TPO-cre) rapidly develop PDTCs and anaplastic thyroid cancer with complete lethality by weaning, suggesting that Braf and Hras, in cooperation with PI3K signaling, likely play distinct roles in the development and progression of disease. We next sought to dissect the role of Hras versus Braf activation in FTC versus PTC development. We derived stable cell lines from HrasG12V/Ptenhom/TPO-cre and BrafV600E/Ptenhom/TPO-cre tumors in order to identify cellular and molecular consequences of Hras versus Braf activation and their potential impact on tumor phenotype. We have found significant differences in phosphorylation of kinases in response to Hras versus Braf activation. Hras activation leads to increased phosphorylation of mTOR effectors, while Braf activation increases CREB activation. Studies are ongoing to identify the molecular mechanism of these observed differences. We have also shown a significant decrease in the growth of HrasG12V/Ptenhom (p=0.0009) and BrafV600E/Ptenhom (p=0.0001) cells treated with the MEK1/2 inhibitor PD0325901, suggesting that activated Hras or Braf-even in the context of Pten loss-partially relies on MAPK signaling to reach its full oncogenic potential. We have recently employed a PCR array approach to identify differences in the expression of genes related to the MAPK pathway in HrasG12V/Ptenhom and BrafV600E/Ptenhom cell lines. We noted an up-regulation of Myc, Cdkn1a, and Sfn in BrafV600E/Ptenhom cells in comparison to HrasG12V/Ptenhom cells, which may contribute to the different pathophysiology of HrasG12V/Ptenhom and BrafV600E/Ptenhom tumor sub-types. Because FTCs and PTCs have different responses to therapy, we seek to identify the cellular and physiological consequences of Ras versus Raf activation which will hopefully aid in the discovery of novel therapeutic and prevention strategies for thyroid cancer.

Citation Format: Lee Ann King, Jeffrey Knauf, Ronald Ghossein, James Fagin, Aime T. Franco. Hras versus Braf activation determines follicular versus papillary thyroid cancer development. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4291. doi:10.1158/1538-7445.AM2013-4291

Abstract 1075: STAT3 signaling in thyroid cancer

Here, we examined the contribution of STAT3 activation in papillary thyroid carcinoma (PTC), which constitutes 80% of all thyroid malignancies. We initially examined STAT3 activation (i.e. Y705 phosphorylation) by IHC in 80 primary PTCs. Approximately 50% of the tumors expressed nuclear pSTAT3. In general, positive cancer cells were found on the edge of the tumor and in association with the stroma (also strongly pSTAT3 positive). The inner part of the tumor was generally negative, as well as all solid PTCs. Additionally, we examined human thyroid cancer derived cell lines and determined that STAT3 was phosphorylated in ∼50% and was regulated by the IL-6/gp130/JAK pathway, similarly to what has been described in breast and lung cancers.

To assess STAT3's role in thyroid cancer, we evaluated the effects of STAT3 under-expression in two models: thyroid cancer derived cell lines where STAT3 levels were reduced using a short hairpin and a transgenic model of PTC lacking STAT3. We observed no significant effects on in vitro growth, migration and invasion as a consequence of reduced STAT3 levels in cancer cell lines. However, in vivo (xenografts in nude mice) the tumors with low STAT3 were significantly larger compared to control (STAT3 expressing) tumors. Similarly, in a transgenic model of PTC lacking STAT3, tumors were larger, more cellular with evidence of increased proliferation compared to the STAT3 expressing cancers. RNA expression analysis of the human xenografts suggested that tumors deficient in STAT3 have downregulated death-promoting genes. In conclusion, our data suggests that in thyroid cancer STAT3 can function as a tumor suppressor, contrary to the current dogma where STAT3 is considered to be oncogenic. We are currently determining whether STAT3's effect on tumorigenesis is dependent on “activated” or total STAT3 and hope to identify the specific molecular pathways involved.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1075. doi:10.1158/1538-7445.AM2011-1075

Molecular, morphologic, and outcome analysis of thyroid carcinomas according to degree of extrathyroid extension

BACKGROUND

The impact of varying degrees of extrathyroid extension (ETE), especially microscopic ETE (METE), on survival in thyroid carcinomas (TC) has not been well established. Our objective was to analyze ETE at the molecular and histologic levels and assess the effect of its extent on outcome.

METHODS

All cases of TC with ETE but without nodal metastases at presentation (NMP) were identified over a 20-year period and grouped into gross and METE. Twelve papillary thyroid carcinomas (PTCs) without ETE and NMP were also analyzed. Cases with paraffin tissues were subjected to mass spectrometry genotyping encompassing the most significant oncogenes in TC: 111 mutations in RET, BRAF, NRAS, HRAS, KRAS, PIK3CA, and AKT1, and other related genes were surveyed.

RESULTS

Eighty-one (10%) of 829 patients in the database had ETE and no NMP. There was a much higher frequency of poorly differentiated and anaplastic carcinomas (12/29, 41%) in patients with gross ETE than in those with METE (3/52, 6%) (p < 0.01). There was a higher disease-specific survival (DSS) in patients with METE than in those with gross ETE (p < 0.0001). Except for an anaplastic case, no recurrences were detected in 45 patients with METE, including 23 PTC patients followed up for a median of 10 years without radioactive iodine therapy. Within patients with gross invasion into trachea/esophagus, tumors with high mitotic activity and/or tumor necrosis correlated with worse DSS (p < 0.05). Fifty-six cases with ETE were genotyped as follows: BRAFV600E, 39 (70%); BRAFV600E-AKT1, 1 (1.8%); NRAS, 1 (1.8%); KRAS, 1 (1.8%); RET/PTC, 3 (5%); wild type, 11 (19.6%). Within PTCs, BRAF positivity rate increased the risk of ETE (p = 0.01). If PTC follicular variants are excluded, BRAF positivity does not correlate with ETE status within classical/tall cell PTC.

CONCLUSION

(i) PTCs with METE without NMP have an extremely low recurrence rate in contrast to tumors with gross ETE. (ii) High mitotic activity and/or tumor necrosis confers worse DSS even in patients stratified for gross ETE in trachea/esophagus. (iii) BRAF positivity correlates with the presence of ETE in PTC, but this relationship is lost within classical/tall cell PTC if follicular variants are excluded from the analysis.

Abstract 3138: Stat3 signaling in thyroid cancer

In this study, we addressed the relevance and regulation of Stat3 activation in thyroid cancer. Papillary Thyroid Carcinoma (PTC) comprises almost 80% of thyroid neoplasias and 70% of PTC present activating alterations of components of the ERK-MAPK pathway, either BRAF mutations, RET/PTC rearrangements or RAS mutations. PTCs often display a strong desmoplastic reaction, where tumor is surrounded by a dense stroma and infiltrated with inflammatory cells. To examine the role of Stat3 in thyroid tumours and its putative relation to the associated inflammatory reaction, we analysed Stat3 activation (i.e. Y705-phosphorylation) by IHC in 58 samples of PTC. Approximately 50% of the tumors express pStat3. Frequently, nuclear positivity is only observed in the edge of the tumor as well as in the thyroid cells within tumor stroma. The inner part of the tumor is generally negative. Using multiple cell line models of PTC we observe that both RET/PTC and BRAFV600E expression can lead to Stat3 activation. Similarly, transgenic models of both BRAFV600E and RET/PTC also demonstrate high levels of pStat3 in particular on the inflammatory/leading edge of the tumor. We hypothesize that Stat3 activation, particularly in BRAFV600E tumors, may result from a paracrine effect of stromal cells-derived factors in the adjacent tumor cells. Stat3 is principally activated by autocrine/paracrine IL-6/Jak signaling in lung and breast tumors. Similarly, here we demonstrate that pan-Jak inhibitors block Stat3 activation in PTC cell lines. Furthermore, IL-6 signaling appears to mediate Stat3 activation in RET/PTC, BRAFV600E and RAS expressing cell lines. BRAFV600E knockdown led to a significant decrease of IL-6 levels, as well as of pStat3. In conclusion, we have found that Stat3 is activated in PTC, and that, particularly in BRAFV600E tumors, such activation may result from a paracrine effect of stromal cells through upregulation of IL-6/Jak pathway.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3138.