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Abstract Background This investigator-initiated phase II trial aimed to evaluate the efficacy of cabozantinib in combination with nivolumab and ipilimumab (CaboNivoIpi) in previously treated patients with radioactive iodine-refractory differentiated thyroid cancer. Methods Eligible patients with radioactive iodine-refractory differentiated thyroid cancer who progressed on 1 prior line of vascular endothelial growth factor receptor-targeted therapy received a 2-week run-in of cabozantinib monotherapy followed by CaboNivoIpi for 4 cycles (cycle length = 6 weeks), followed by cabozantinib plus nivolumab (cycle length = 4 weeks) until disease progression. The primary endpoint was objective response rate (ORR) within the first 6 months of treatment. A Simon optimal 2-stage design allowed for an interim analysis after accrual of 10 evaluable patients. At least 5 responses were needed to proceed to stage 2. Results Among 11 patients enrolled, the median age was 69 years. Prior vascular endothelial growth factor receptor-targeted therapies included lenvatinib, pazopanib, and sorafenib plus everolimus. Median follow-up was 13.4 months. Among 10 evaluable patients, ORR within the first 6 months of treatment was 10% (1 partial response). Median progression-free survival was 9 months (95% CI, 3.0–not reached) and median overall survival was 19.2 months (95% CI, 4.6–not reached). Grade 3/4 treatment-related adverse events (AEs) were noted in 55% (6/11) and grade 5 AEs in 18% (2/11) of patients. The most common treatment-related AE was hypertension. The study did not reach its prespecified efficacy threshold. Conclusion CaboNivoIpi had low ORRs and a high rate of grade ≥3 treatment-related AEs. Clinical Trial Registration NCT03914300

OBJECTIVE The aims of this study were to 1) define the incidence of transforaminal lumbar interbody fusion (TLIF) interbody subsidence; 2) determine the relative importance of preoperative and intraoperative patient- and instrumentation-specific risk factors predictive of postoperative subsidence using CT-based assessment; and 3) determine the impact of TLIF subsidence on postoperative complications and fusion rates. METHODS All adult patients who underwent one- or two-level TLIF for lumbar degenerative conditions at a multi-institutional academic center between 2017 and 2019 were retrospectively identified. Patients with traumatic injury, infection, malignancy, previous fusion at the index level, combined anterior-posterior procedures, surgery with greater than two TLIF levels, or incomplete follow-up were excluded. Interbody subsidence at the superior and inferior endplates of each TLIF level was directly measured on the endplate-facing surface of both coronal and sagittal CT scans obtained greater than 6 months postoperatively. Patients were grouped based on the maximum subsidence at each operative level classified as mild, moderate, or severe based on previously documented < 2-mm, 2- to 4-mm, and ≥ 4-mm thresholds, respectively. Univariate and regression analyses compared patient demographics, medical comorbidities, preoperative bone quality, surgical factors including interbody cage parameters, and fusion and complication rates across subsidence groups. RESULTS A total of 67 patients with 85 unique fusion levels met the inclusion and exclusion criteria. Overall, 28% of levels exhibited moderate subsidence and 35% showed severe subsidence after TLIF with no significant difference in the superior and inferior endplate subsidence. Moderate (≥ 2-mm) and severe (≥ 4-mm) subsidence were significantly associated with decreases in cage surface area and Taillard index as well as interbody cages with polyetheretherketone (PEEK) material and sawtooth surface geometry. Severe subsidence was also significantly associated with taller preoperative disc spaces, decreased vertebral Hounsfield units (HU), the absence of bone morphogenetic protein (BMP) use, and smooth cage surfaces. Regression analysis revealed decreases in Taillard index, cage surface area, and HU, and the absence of BMP use predicted subsidence. Severe subsidence was found to be a predictor of pseudarthrosis but was not significantly associated with revision surgery. CONCLUSIONS Patient-level risk factors for TLIF subsidence included decreased HU and increased preoperative disc height. Intraoperative risk factors for TLIF subsidence were decreased cage surface area, PEEK cage material, bullet cages, posterior cage positioning, smooth cage surfaces, and sawtooth surface designs. Severe subsidence predicted TLIF pseudarthrosis; however, the causality of this relationship remains unclear.

3150 Background: Selpercatinib, a first-in-class highly selective and potent RET kinase inhibitor with CNS activity, is approved in multiple countries for the treatment of RET-activated cancers. Current indications for RET mutant disease are limited to MTC. This analysis examined if selpercatinib was effective in non-MTC, RET mutation positive tumors and whether certain RET mutations demonstrated better activity (n=23; data cut-off: 13Jan2023). Methods: The phase 1/2 LIBRETTO-001 trial (NCT03157128) enrolled pts with locally advanced/metastatic RET-altered solid tumors, including pts with RET mutations in tumors other than MTC. Mutations must be known to be activating based on activity in MTC or other published evidence. Primary endpoint was objective response rate (ORR) by independent review committee (IRC). Secondary endpoints included ORR by investigator (INV), duration of response (DoR), progression-free survival (PFS), and safety. Results: Fourteen different tumor types were identified among the 23 pts with non-MTC RET-mutated tumors. This included 8 tumors from the Multiple Endocrine Neoplasia (MEN) syndrome spectrum; adrenal (pheochromocytoma; n=5), paraganglioma (n=2), neuroendocrine (n=1) (Table). Most of the mutations were located in extracellular cysteine-rich domain (CRD) and in the tyrosine kinase domain (TKD) of RET. In 23 efficacy-evaluable pts, confirmed ORR by IRC was 21.7% (5/23, 95% CI: 7.5, 43.7). ORR by IRC for pts with MEN-associated tumors (n=8) was 37.5% while five of these pts (62.5%) had stable disease lasting at least 16 weeks (SD16+). ORR by IRC for the sub-population with pheochromocytoma (n=5) was 40.0% and for pts with tumors manifesting RET extracellular cysteine mutations (n=5) was 60.0%. Of the 15 pts with non-MEN-associated tumors, 2 pts (8.7%; mutation in TKD) had a partial response (both with NSCLC adenocarcinoma, of which one had co-existent MTC). For the overall pts, the median DoR was 12.2 months (95% CI: 3.8, NE) and median PFS was 5.5 months (95% CI: 1.8, 19.4). No new safety signals were identified compared to previous reports. One grade 5 AE, general physical health deterioration, was observed and deemed by INV as not related to selpercatinib. Conclusions: This study suggests that RET-mutated, MEN-associated cancers (adrenal, paraganglioma, neuroendocrine) may benefit from selpercatinib treatment, which could be mediated through mutations in the extracellular CRD. The non-MTC RET-mutated tumor types appear not to derive benefit from selpercatinib. Clinical trial information: NCT03157128 . [Table: see text]

Study Design: Retrospective cohort analysis. Objective: To determine whether the C2 exposure technique was a predictor of change in cervical alignment and patient-reported outcomes measures (PROMs) after posterior cervical decompression and fusion (PCDF) for degenerative indications. Background: In PCDF handling of the C2 posterior paraspinal musculature during the operative approach varies by surgeon technique. To date, no studies have investigated whether maintenance of the upper cervical semispinalis cervicis attachments as compared with complete reflection of upper cervical paraspinal musculature from the posterior bony elements is associated with superior radiographic and clinical outcomes after PCDF. Patients and Methods: All adult patients who underwent C2–T2 PCDF for myelopathy or myeloradiculopathy at multi-institutional academic centers between 2013 and 2020 were retrospectively identified. Patients were dichotomized by the C2 exposure technique into semispinalis preservation or midline muscular reflection groups. Preoperative and short and long-term postoperative radiographic outcomes (upper cervical alignment, global alignment, and fusion status) and PROMs (Visual Analog Scale–Neck, Neck Disability Index, and Short Form-12) were collected. Univariate analysis compared patient factors, radiographic measures, and PROMs across C2 exposure groups. Results: A total of 129 patients met the inclusion/exclusion criteria (73 muscle preservation and 56 muscle reflection). Patients in the muscular preservation group were on average younger (P = 0.005) and more likely to have bone morphogenic protein (P < 0.001) and C2 pars screws (P = 0.006) used during surgery. Preoperative to postoperative changes in C2 slope, C2 tilt, C2–C3 segmental lordosis, C2–C3 listhesis, C0–C2 Cobb angle, proximal junctional kyphosis, ADI, C1 lamina-occiput distance, C2 sagittal vertical axis, C2–C7 lordosis, and PROMs at all follow-up intervals did not vary significantly by C2 exposure technique. Likewise, there were no significant differences in fusion status, C2–C3 pseudoarthrosis, C2 screw loosening, and complication and revision rates between C2 exposure groups. Conclusions: Preservation of C2 semispinalis attachments versus muscular reflection did not significantly impact cervical alignment, clinical outcomes, or proximal junction complications in long-segment PCDF. Level of Evidence: Level III.

Importance Oncocytic (Hürthle cell) thyroid carcinoma is a follicular cell-derived neoplasm that accounts for approximately 5% of all thyroid cancers. Until recently, it was categorized as a follicular thyroid carcinoma, and its management was standardized with that of other differentiated thyroid carcinomas. In 2022, given an improved understanding of the unique molecular profile and clinical behavior of oncocytic thyroid carcinoma, the World Health Organization reclassified oncocytic thyroid carcinoma as distinct from follicular thyroid carcinoma. The International Thyroid Oncology Group and the American Head and Neck Society then collaborated to review the existing evidence on oncocytic thyroid carcinoma, from diagnosis through clinical management and follow-up surveillance. Observations Given that oncocytic thyroid carcinoma was previously classified as a subtype of follicular thyroid carcinoma, it was clinically studied in that context. However, due to its low prevalence and previous classification schema, there are few studies that have specifically evaluated oncocytic thyroid carcinoma. Recent data indicate that oncocytic thyroid carcinoma is a distinct class of malignant thyroid tumor with a group of distinct genetic alterations and clinicopathologic features. Oncocytic thyroid carcinoma displays higher rates of somatic gene variants and genomic chromosomal loss of heterozygosity than do other thyroid cancers, and it harbors unique mitochondrial DNA variations. Clinically, oncocytic thyroid carcinoma is more likely to have locoregional (lymph node) metastases than is follicular thyroid carcinoma—with which it was formerly classified—and it develops distant metastases more frequently than papillary thyroid carcinoma. In addition, oncocytic thyroid carcinoma rarely absorbs radioiodine. Conclusions and Relevance The findings of this review suggest that the distinct clinical presentation of oncocytic thyroid carcinoma, including its metastatic behavior and its reduced avidity to radioiodine therapy, warrants a tailored disease management approach. The reclassification of oncocytic thyroid carcinoma by the World Health Organization is an important milestone toward developing a specific and comprehensive clinical management for oncocytic thyroid carcinoma that considers its distinct characteristics.

Objective: Redifferentiation therapy (RDT) can restore radioactive iodine (RAI) uptake in differentiated thyroid cancer (DTC) cells to enable salvage 131 I therapy for previously RAI refractory (RAIR) disease. This study evaluated the clinical outcomes of patients who underwent RDT and identified clinicopathologic characteristics predictive of RAI restoration following RDT. Methods: This is a retrospective case series of 33 patients with response evaluation criteria in solid tumors (RECIST)-progressive metastatic RAIR-DTC who underwent RDT between 2017 and 2022 at the Mayo Clinic (Rochester, MN). All patients underwent genomic profiling and received MEK, RET or ALK inhibitors alone, or combination BRAF -MEK inhibitors for 4 weeks. At week 3, those with increased RAI avidity in metastatic foci received high-dose 131 I therapy. Baseline and clinicopathologic outcomes were comprehensively reviewed. Results: Of the 33 patients, 57.6% had restored RAI uptake following RDT (Redifferentiated subgroup). 42.1% (8/19) with papillary thyroid cancers (PTC), 100% (4/4) with invasive encapsulated follicular variant PTCs (IEFV-PTCs), and 100% (7/7) with follicular thyroid cancers (FTC) redifferentiated. All (11/11) RAS mutant tumors redifferentiated compared with 38.9% (7/18) with BRAF mutant disease (6 PTC and 1 IEFV-PTC). 76.5% (13/17) of redifferentiated and 66.7% (8/12) of non-redifferentiated patients achieved a best overall RECIST response of stable disease (SD) or non-complete response/non-progressive disease. Both subgroups had a median 12% tumor shrinkage at 3 weeks on drug(s) alone. The redifferentiated subgroup, following high-dose 131 I therapy, achieved an additional median 20% tumor reduction at 6 months after RDT. There were no statistically significant differences between both groups in progression free survival (PFS), time to initiation of systemic therapy, and time to any additional therapy. Of the entire cohort, 6.1% (2/33) experienced histologic transformation to anaplastic thyroid cancer, 15.1% (5/33) died, and all had redifferentiated following RDT and received 131 I therapy. Conclusion: RDT has the potential to restore RAI avidity and induce RECIST responses following 131 I therapy in select patients with RAIR-DTC, particularly those with RAS -driven “follicular” phenotypes. In patients with PTC, none of the evaluated clinical outcomes differed statistically between the redifferentiated and non-redifferentiated subgroups. Further studies are needed to better characterize the long-term survival and/or safety outcomes of high-dose RAI following RDT, particularly whether it could be associated with histologic anaplastic transformation.

Abstract Disclosure: S. Tella: None. J.C. Morris: None. M. Rivera: None. S. Gupta: None. M.M. Ryder: None. Introduction: NUT carcinoma is a rare subtype of squamous cell carcinoma defined by NUTM1 rearrangements encoding NUT-fusion oncoproteins with a very dismal prognosis. Recent data showed that NUTM1 rearranged carcinoma of the thyroid can mimic other thyroid primaries but NSD3-NUTM1 fusions aid in the diagnosis. Other than systemic chemotherapy with ifosfamide-based therapies and bromodomain inhibitors, therapeutic options for metastatic NUTM1 rearranged carcinoma of thyroid are limited. Herein, we describe a case of NUTM1 carcinoma of thyroid that had an impressive response to lenvatinib. Clinical case: We describe a case of a 41-year-old Caucasian male who presented to urgent care with acute onset aphonia and was eventually diagnosed with poorly differentiated thyroid carcinoma of size 4 x 4 cms extending into the internal jugular vein. He was managed with partial resection of the mass, internal jugular vein ligation, and a right select neck dissection. He had R2 resection due to possible vascular or airway invasion. As such, he received external beam radiation 70 Gy with 35 fractions with concurrent cisplatin followed by 200 mci radio-iodine therapy. The radiation therapy was complicated by the formation of a tracheo-esophageal fistula. A follow-up FDG-avid PET scan demonstrated residual thyroid bed disease and oligometastatic disease in bones. He received a couple of Stereotactic Body Radiation Therapy twice for bone lesions. Unfortunately, he had rapid disease progression with large pleural-based nodules and histology showed poorly differentiated thyroid carcinoma. NUT1 IHC stain was negative. We simultaneously obtained next-generation sequencing (NGS) and started him on lenvatinib 20 mg. Interestingly, NGS showed NSD3-NUTM1 fusions favoring the diagnosis of NUTM1 rearranged carcinoma of thyroid. He had an impressive partial response to lenvatinib within 4 weeks of initiation of lenvatinib and the response is sustained on 8-month follow-up. He tolerated lenvatinib reasonably without any unexpected complications. In an event of progression, we intend to consider a clinical trial, chemotherapy in combination with bromodomain inhibitors, or another anti-angiogenic tyrosine kinase inhibitor therapy. Conclusions: We noticed an impressive and sustained partial response in NUTM1 rearranged carcinoma of thyroid with anti-angiogenic multi-kinase inhibitor, lenvatinib opening new avenues of targeted therapy in the therapeutic landscape of NUT1 carcinomas. Importantly, NUT1 stain could be negative and NGS is the gold standard for accurate diagnosis. Although our study is limited by one case report, we hope that by highlighting the spectrum of this disease that more cases will be recognized, facilitating risk stratification and improved treatment, and further enabling future studies to explore the clinical management and biology of NUTM1 rearranged carcinoma of thyroid. Presentation: Thursday, June 15, 2023

Abstract Disclosure: D. Toro-Tobon: None. J.C. Morris: None. C. Hilger: None. C.S. Peskey: None. D.M. Jolanta: None. M.M. Ryder: None. Objective: Patients with metastatic differentiated thyroid cancer (DTC) that are radioactive iodine (RAI) refractory (RAIR) have a poor prognosis. Redifferentiation therapy (RDT) has emerged as a potential approach to restore RAI avidity in this disease. The aim of this study was to examine the efficacy and predictors of RAI restoration in RAIR disease, as well as examine the outcomes of patients re-treated with high dose RAI following RDT. Methods: A retrospective review was conducted of 33 patients with RECIST-progressive metastatic RAIR-DTC who underwent RDT between 2017 and 2022 at the Mayo Clinic. All patients underwent genomic profiling, and either MEK inhibitor alone or combination BRAF-MEK inhibitors were prescribed for 4 weeks. At week 3, Thyrogen-stimulated I-123 whole body scans were performed. Those with increased RAI avidity in metastatic foci received high dose I-131 therapy using a previously published modified dosimetry protocol. Baseline and clinicopathologic outcomes were comprehensively reviewed. Results: Of the 33 patients, 12 of 23 (52%) with papillary thyroid cancers (PTC), 4 of 4 (100%) with follicular variant PTCs (FV-PTC), and 7 of 7 (100%) with follicular thyroid cancers (FTC) had restored RAI avidity following RDT using dabrafenib/trametinib (7 for BRAF mutant disease) or trametinib monotherapy (12 for RAS mutant disease). All 11 (100%) RAS mutant tumors (2 PTC, 3 FV-PTC, and 6 FTC) had RAI avidity restoration compared to 7 (36%) with BRAF mutant disease (6 PTC, and 1 FV-PTC). Of the 19 patients (57%) with restored RAI avidity (responders), 18 (94%) received I-131 with a median dose of 294 mCi. The median thyroglobulin (Tg) in responders was 294 mIU/L as compared to 29 mIU/L in non-responders. Following RDT-facilitated I-131 treatment, 94.7% achieved RECIST defined objective response (complete or partial response, stable disease, non-complete response/non-progressive disease) with a median progression free survival of 18 months and an overall survival of 30 months. Overall, patients with FTC (p=0.01), RAS mutation (p&lt;0.001), Tg of 294 mIU/L or more (p=0.03), largest tumor diameter of 1.7 cm or less (p=0.05), bone metastasis (p=0.007), and without locoregional nodal disease (p=0.04), were more likely to demonstrate restored RAI avidity following RDT. Of the entire cohort, 2 (6%) patients experienced histologic transformation to anaplastic thyroid cancer and 5 (15%) patients died, all had had RAI restoration and received high-dose RAI following RDT. Conclusion: RDT has the potential to restore RAI avidity and induce RECIST responses following I-131 therapy in select patients with RAIR-DTC, particularly those with RAS mutations and ‘follicular’ phenotypes. Further studies are needed to better characterize the long-term survival and/or safety outcomes of high-dose RAI following RDT, particularly whether it could be associated with histologic transformation. Presentation Date: Saturday, June 17, 2023

SAGE-Journals-Accessible-Video-Player 10.1089/ve.2023.0020.M1 sj-vid-1-vde-10.1089_ve.2023.0020

Study Design. Retrospective cohort study. Objective. The present study is the first to assess the impact of paraspinal sarcopenia on patient-reported outcome measures (PROMs) following cervical laminoplasty. Background. While the impact of sarcopenia on PROMs following lumbar spine surgery is well-established, the impact of sarcopenia on PROMs following laminoplasty has not been investigated. Methods. We performed a retrospective review of patients undergoing laminoplasty from C4-6 at a single institution between 2010 and 2021. Two independent reviewers utilized axial cuts of T2-weighted magnetic resonance imaging sequences to assess fatty infiltration of the bilateral transversospinales muscle group at the C5-6 level and classify patients according to the Fuchs Modification of the Goutalier grading system. PROMs were then compared between subgroups. Results. We identified 114 patients for inclusion in this study, including 35 patients with mild sarcopenia, 49 patients with moderate sarcopenia, and 30 patients with severe sarcopenia. There were no differences in preoperative PROMs between subgroups. Mean postoperative neck disability index scores were lower in the mild and moderate sarcopenia subgroups (6.2 and 9.1, respectively) than in the severe sarcopenia subgroup (12.9, P=0.01). Patients with mild sarcopenia were nearly twice as likely to achieve minimal clinically important difference (88.6 vs. 53.5%; P<0.001) and six times as likely to achieve SCB (82.9 vs. 13.3%; P=0.006) compared with patients with severe sarcopenia. A higher percentage of patients with severe sarcopenia reported postoperative worsening of their neck disability index (13 patients, 43.3%; P=0.002) and Visual Analog Scale Arm scores (10 patients, 33.3%; P=0.03). Conclusion. Patients with severe paraspinal sarcopenia demonstrate less improvement in neck disability and pain postoperatively and are more likely to report worsening PROMs following laminoplasty. Level of Evidence. 3