Outcomes after robotic thymectomy in nonthymomatous versus thymomatous patients with acetylcholine-receptor-antibody-associated myasthenia gravis.

The aim of this study was to investigate the surgical and long-term neurological outcomes of patients with acetylcholine-receptor-antibody-associated myasthenia gravis (AChR-MG) who underwent robotic thymectomy (RATS). We retrospectively analyzed the clinical-pathological data of all patients with AChR-MG who underwent RATS using the DaVinci® Robotic System at the MUMC+ between April 2004 and December 2018. Follow-up data were collected from 60 referring Dutch hospitals. In total, 230 myasthenic patients including 76 patients with a thymoma (33.0%) were enrolled in this study. Mean follow-up time, procedure time and hospitalization were, respectively 65.7 ± 43.1 months, 111±52.5 min and 3.3 ± 2.2 days. Thymomatous patients had significantly more frequently and more severe complications than nonthymomatous patients (18.4% vs. 3.9%, p<0.001). Follow up data was available in 71.7% of the included patients. The Myasthenia Gravis Foundation of America postintervention score showed any kind of improvement of MG-symptoms after RATS in 82.4% of the patients. Complete stable remission (CSR) or pharmacological remission (PR) of MG was observed in 8.4% and 39.4% of the patients, respectively. Mean time till CSR/PR remission after thymectomy was 26.2 ± 29.2 months. No statistical difference was found in remission or improvement in MGFA scale between thymomatous and nonthymomatous patients. RATS is safe and feasible in patients with MG. The majority of the patients (82.4%) improved after thymectomy. CSR and PR were observed in 8.4% and 39.4% of the patients, respectively, with a mean of 26.2 months after thymectomy. Thymomatous patients had more frequently and more severe complications compared to nonthymomatous patients.

Immune checkpoint blockers in patients with unresectable or metastatic thymic epithelial tumours: A meta-analysis.

BACKGROUND: For patients with advanced thymic epithelial tumours (TET), there is no standard second-line treatment after platinum-based chemotherapy. Although immune checkpoint blockers (ICB) are a potential treatment strategy, their efficacy seems limited with an increased risk of immune-related adverse events (ir-AEs), thus hampering their application in daily clinical practice. METHODS: We performed a meta-analysis to better evaluate the existing evidence about the activity and safety of ICB in the setting of unresectable or metastatic advanced TET previously treated with platinum-based chemotherapy. RESULTS: Six phase I/II trials met the eligibility criteria including a total of 166 evaluable patients (77% thymic carcinoma, 23% thymoma) evaluable for activity after being treated with pembrolizumab, nivolumab, avelumab or atezolizumab. The overall response rate to ICB was 18.4% (95% CI: 12.3-26.5), and the one-year progression-free survival rate and one-year overall survival rate were 26.0% (95% CI: 19.6-34.6) and 66.9% (95% CI: 59.6-75.2%), respectively. The incidence of grade 3-5 ir-AEs was 26.4%, with 17.1% in thymic carcinoma and 58.3% in thymoma. CONCLUSIONS: Despite the absence of a robust demonstration of efficacy in the context of randomised trials, our results suggest ICB as a potential strategy in patients with pretreated TET, mainly among patients with thymic carcinoma. Close monitoring is strongly advised to detect severe immune-toxicity.

Novel treatment strategies for acetylcholine receptor antibody-positive myasthenia gravis and related disorders.

The presence of autoantibodies directed against the muscle nicotinic acetylcholine receptor (AChR) is the most common cause of myasthenia gravis (MG). These antibodies damage the postsynaptic membrane of the neuromuscular junction and cause muscle weakness by depleting AChRs and thus impairing synaptic transmission. As one of the best-characterized antibody-mediated autoimmune diseases, AChR-MG has often served as a reference model for other autoimmune disorders. Classical pharmacological treatments, including broad-spectrum immunosuppressive drugs, are effective in many patients. However, complete remission cannot be achieved in all patients, and 10% of patients do not respond to currently used therapies. This may be attributed to production of autoantibodies by long-lived plasma cells which are resistant to conventional immunosuppressive drugs. Hence, novel therapies specifically targeting plasma cells might be a suitable therapeutic approach for selected patients. Additionally, in order to reduce side effects of broad-spectrum immunosuppression, targeted immunotherapies and symptomatic treatments will be required. This review presents established therapies as well as novel therapeutic approaches for MG and related conditions, with a focus on AChR-MG.

Robotic Thymectomy for Thymomas: A Retrospective Follow-up Study in the Netherlands.

BACKGROUND: The Maastricht University Medical Center+ is a Dutch center of expertise appointed by the Netherlands Federation of University Medical Centers for the treatment of thymomas. The aim of this study was to investigate the long-term oncologic, surgical, and neurologic outcomes of all patients who underwent a robotic thymectomy for a thymoma at Maastricht University Medical Center+. METHODS: We retrospectively analyzed the clinical-pathologic data of all consecutive patients with a thymoma who underwent robotic thymectomy using the DaVinci robotic system at Maastricht University Medical Center+ between April 2004 and December 2018. Follow-up data were collected from 60 referring Dutch hospitals. RESULTS: In total, 398 robotic thymectomies were performed, and 130 thymomas (32.7%) were found. Median follow-up time was 46 months; median procedure time, 116 minutes; and median hospitalization time, 3 days. In 8.4% of patients, a conversion was performed, and in 20.8%, a complication was registered. The majority of myasthenic patients with a thymoma went into remission, mostly within 12 to 24 months after thymectomy (81%). No statistical difference was found in the number of complications, conversions, incomplete resections, or deaths between patients with myasthenia gravis and nonmyasthenic patients. Thirty-six patients (27.7%) underwent postoperative radiotherapy. The recurrence rate was 9.1%, and the 5-year thymoma-related survival rate was 96.6%. CONCLUSIONS: Robotic thymectomy was found to be safe and feasible for early stage thymomas, most advanced-stage thymomas, and thymomatous myasthenia gravis. A national guideline could contribute to the improvement of the oncologic follow-up of thymic epithelial tumors in the Netherlands.

The association between anti-acetylcholine receptor antibody level and clinical improvement in myasthenia gravis.

BACKGROUND AND PURPOSE: Anti-acetylcholine receptor (AChR) antibodies (ab) in the serum are detected in most patients with generalized myasthenia gravis (MG) and used as a diagnostic tool. The aim of this study was to analyse a possible association between anti-AChR-ab serum levels and clinical improvement of MG. METHODS: The Maastricht University Medical Center is a centre of expertise for the treatment of MG. Between 1997 and 2020, more than 4000 anti-AChR-ab blood samples were measured for clinical care using a quantitative radioimmunoassay technique. These results, in combination with clinical status obtained from the patients' electronic patient files, were retrospectively analysed by a single blinded clinician. Symptoms of MG were classified using the Myasthenia Gravis Foundation of America (MGFA) scale. RESULTS: In total, 90 anti-AChR-ab-positive MG patients with 837 blood samples were included. The median follow-up time was 72 months. The majority of the included patients were women (61.1%), were on immunosuppressive drug therapy (88.9%), and underwent a thymectomy (54.4%). Multilevel logistic regression analysis showed a significantly inverse association between change in anti-AChR-ab level and the odds of MGFA improvement (per 10% decrease of anti-AChR-ab level: odds ratio 1.21, 95% confidence interval 1.12-1.31; p < 0.001). CONCLUSIONS: A change in anti-AChR-ab serum level is associated with clinical status in patients with MG. Analyses of anti-AChR-ab are not only useful for diagnostics but also in follow-up of adult symptomatic patients with MG. The use of repetitive anti-AChR-ab serum levels might be valuable in long-term monitoring for clinical improvement in patients with MG, however, further research is required for specific recommendations.

Optimal delineation of the clinical target volume for thymomas in the post-resection setting: A multi-center study.

BACKGROUND: The definition of the clinical target volume (CTV) for post-operative radiotherapy (PORT) for thymoma is largely unexplored. The aim of this study was to analyze the difference in CTV delineation between radiation oncologists (RTO) and surgeons. METHODS: This retrospective multi-center study enrolled 31 patients who underwent PORT for a thymoma from five hospitals. Three CTVs were delineated per patient: one CTV by the RTO, one CTV by the surgeon (blinded to the results of the RTO) and a joint CTV after collaboration. Volumes (cm3), Hausdorff distances (HD) and Dice similarity coefficients (DSC) were analyzed. RESULTS: RTO delineated significantly bigger CTVs than surgeons (mean: 93.9 ± 63.1, versus 57.9 ± 61.3 cm3, p = 0.003). Agreement was poor between RO and surgeons, with a low mean DSC (0.34 ± 0.21) and high mean HD of 4.5 (±2.2) cm. Collaborative delineation resulted in significantly smaller volumes compared to RTO (mean 57.1 ± 58.6 cm3, p < 0.001). A mean volume of 18.9 (±38.1) cm3 was included in joint contours, but missed by RTO. Conversely, a mean volume of 55.7 (±39.9) cm3 was included in RTO's delineations, but not in the joint delineations. CONCLUSIONS: To the best of our knowledge, this is the first study investigating CTV definition in thymoma. We demonstrated a significant variability between RTO and surgeons. Joint delineation prompted revisions in smaller CTV as well as favoring the surgeons' judgement, suggesting that surgeons provided relevant insight into other risk areas than RTO. We recommend a multidisciplinary approach to PORT for thymomas in clinical practice.

Symptomatic mediastinal mass in a 32-year-old male.

Most bronchogenic cysts are found incidentally and clinicians should be aware of an atypical case presentation. Total surgical resection is the treatment of choice of a bronchogenic cyst, especially in symptomatic patients. https://bit.ly/3uQrFXo.

Subclinical myasthenia gravis in thymomas.

BACKGROUND: A proportion of thymoma-patients without a history of myasthenia gravis (MG) before thymectomy, appears to have positive anti-AChR-antibodies in the serum. These subclinical MG-patients could be underdiagnosed because analyzation of anti-AChR-antibodies in thymomas is not always performed in patients who did not experience neurological symptoms. The prevalence and long-term outcomes of subclinical MG are never described in literature yet. METHODS: We retrospectively analyzed 398 consecutive patients who underwent a robotic-assisted thoracoscopic surgery at the Maastricht University Medical Center+ (MUMC+) between April 2004 and December 2018. In the MUMC+, a robotic approach is the standard surgical approach in patients with thymic diseases. Inclusion criteria were thymomas, thymectomy performed in the MUMC + with a follow-up of at least one year and age above 18 years old. Exclusion criteria were patients with thymic carcinomas, refused participation, or those who were lost to follow-up. RESULTS: Of the 102 included thymoma-patients, 87 patients (85 %) were tested for anti-AChR-antibodies before thymectomy, of which 57 patients were diagnosed with clinical MG and seven subclinical MG-patients were found. Of the 15 patients who were not tested for anti-AChR-antibodies, four more subclinical MG-patients were discovered in the years after thymectomy. The median follow-up time was 62 months. In total, 11 subclinical MG-patients were found, with a mean age of 54 years and predominantly females (64 %). Ten subclinical MG-patients (91 %) developed clinical-MG, within six years after thymectomy. Immunosuppressive drugs were prescribed in five patients. Four patients were diagnosed with a recurrence of the thymoma. No surgical mortality was reported. Two patients died due to a myasthenic crisis. CONCLUSIONS: The prevalence of subclinical MG in thymomas was found to be 10.8 %. One in four patients who experienced no neurological symptoms before thymectomy, appeared to have anti-AChR-antibodies and 91 % of these patients developed clinical MG within six years after the thymectomy. Analyzing anti-AChR-antibodies in the serum is recommended in all suspected thymomas before a thymectomy is performed.

Globe Subluxation following Long-Term High-Dose Steroid Treatment for Myasthenia Gravis.

This case report describes the unusual presentation of a globe subluxation following long-term high-dose oral steroid treatment for myasthenia gravis (MG). The patient presented initially with fluctuating vertical diplopia. Auto-antibodies against the acetylcholine receptor were weakly positive, confirming the diagnosis of MG. After initial treatment with pyridostigmine, the disease evolved to generalized MG. Plasmapheresis and high-dose steroids were started subsequently. As a side effect of this treatment the patient gained about 30 kg in weight and developed steroid myopathy and a prominent cushingoid facies with bilateral exophthalmos. A year after his initial diagnosis he experienced a spontaneous globe subluxation on the left eye. He was able to immediately reposition the globe manually himself. Four months later a new subluxation occurred. Because of these aforementioned severe side effects of the steroid treatment, the methylprednisolone was tapered and replaced by tacrolimus. After about 6 weeks the patient went into remission. We believe, that the spontaneous globe subluxations were caused by a weakness of the extraocular muscles in combination with a significant gain of intraorbital fat tissue, both induced by cumulative, excessive steroids. Steroids are often necessary in the treatment of MG; however, most of the time a high dose of 64 mg is not needed for ocular MG and especially the continuation of a dose of 58 mg or more for a long period is not recommended. Careful follow-up is obligatory to timely recognize side effects. In case of severe side effects or the need for long-term treatment, the use of other immunosuppressive therapies should be considered. Extra care and caution is recommended in patients who are anatomically predisposed with proptosis.

Characterization of the thymus in Lrp4 myasthenia gravis: Four cases.

Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction. Most patients have pathogenic autoantibodies against the acetylcholine receptor (AChR). In the last years a novel subpopulation of MG patients has been described that harbors antibodies against low-density lipoprotein receptor-related protein 4 (Lrp4), another postsynaptic neuromuscular antigen. In early-onset AChR MG (EOMG), the thymus plays an important role in immunopathogenesis, and early thymectomy is beneficial. It is still unknown if the thymus plays any role in Lrp4-MG. In this pilot study, we compared thymus samples from four patients with Lrp4-MG (one pre-treated with immunosuppressive drugs), four non-MG controls and five EOMG patients (not pretreated with immunosuppressive drugs). Immunohistochemistry of the Lrp4-MG thymi revealed normal architecture, with normal numbers and distribution of B-cells, lymphoid follicles and Hassall's corpuscles. Primary CD23+ lymphoid follicles were similarly infrequent in Lrp4-MG and control thymic sections. In none of the control or Lrp4-MG thymi did we find secondary follicles with CD10+ germinal centers. These were evident in 2 of the 5 EOMG thymi, where primary lymphoid follicles were also more frequent on average, thus showing considerable heterogeneity between patients. Even if characteristic pathological thymic changes were not observed in the Lrp4 subgroup, we cannot exclude a role for the thymus in Lrp4-MG pathogenesis, since one Lrp4-MG patient went into clinical remission after thymectomy alone (at one year follow-up) and one more improved after thymectomy in combination with immunosuppressive therapy.