Background: Circulating tumor DNA (ctDNA) is a potential biomarker in pancreatic ductal adenocarcinoma (PDAC). However, studies on residual ctDNA in patients post-chemotherapy are limited. We assessed the prognostic value of residual ctDNA in metastatic PDAC relative to that of carbohydrate antigen 19-9 (CA19-9). Methods: ctDNA analysis using a targeted next-generation sequencing panel was performed at baseline and during chemotherapy response evaluation in 53 patients. Progression-free survival (PFS) and overall survival (OS) were first evaluated based on ctDNA positivity at baseline. For further comparison, patients testing ctDNA-positive at baseline were subdivided based on residual ctDNA into ctDNA responders (no residual ctDNA post-chemotherapy) and ctDNA non-responders (residual ctDNA post-chemotherapy). Additional survival analysis was performed based on CA19-9 levels. Results: The baseline ctDNA detection rate was 56.6%. Although clinical outcomes tended to be poorer in patients with baseline ctDNA positivity than in those without, the differences were not significant. Residual ctDNA post-chemotherapy was associated with reduced PFS and OS. The prognosis of ctDNA responders was better than that of non-responders but did not significantly differ from that of ctDNA-negative individuals (no ctDNA both at baseline and during post-chemotherapy). Compared with ctDNA responses to che-motherapy, a ≥ 50% decrease in the CA19-9 level had less effect on both PFS and OSbased on hazard ratios and significance levels. ctDNA could be monitored in half of the patients whose baseline CA19-9 levels were within the reference range. Conclusions Residual ctDNA analysis post-chemotherapy is a promising approach for predicting the clinical outcomes of patients with metastatic PDAC.

Purpose: To report a case of paraneoplastic autoimmune retinopathy in a patient with a history of testicular cancer.Case summary: A 29-year-old man presented with photopsia and floaters. Initial fundus examination revealed no abnormal findings. However, he returned 1 month later with complaints of visual field defects. Fundus examination revealed diffuse white spots in the macula and midperipheral retina and fundus autofluorescence demonstrated hyper-autofluorescence. Optical coherence tomography showed disruption of the ellipsoid zone sparing the fovea. Visual field examination revealed peripheral visual field defects and an electroretinogram showed reduced rod and cone cell responses. Considering his history of testicular cancer, serum paraneoplastic autoantibody panel testing was performed which revealed borderline levels of anti-recoverin antibody leading to a diagnosis of paraneoplastic autoimmune retinopathy. The patient was treated with oral steroids and mycophenolate mofetil for 1 year. However, there was no improvement in the subjective symptoms or ophthalmologic findings. Conclusions This case of paraneoplastic autoimmune retinopathy in a young man with a history of testicular cancer highlights an early clinical presentation of the disease. It is crucial to recognize that the initial clinical presentation of autoimmune retinopathy can be nonspecific.

Purpose: To report a case of paraneoplastic autoimmune retinopathy in a patient with a history of testicular cancer.Case summary: A 29-year-old man presented with photopsia and floaters. Initial fundus examination revealed no abnormal findings. However, he returned 1 month later with complaints of visual field defects. Fundus examination revealed diffuse white spots in the macula and midperipheral retina and fundus autofluorescence demonstrated hyper-autofluorescence. Optical coherence tomography showed disruption of the ellipsoid zone sparing the fovea. Visual field examination revealed peripheral visual field defects and an electroretinogram showed reduced rod and cone cell responses. Considering his history of testicular cancer, serum paraneoplastic autoantibody panel testing was performed which revealed borderline levels of anti-recoverin antibody leading to a diagnosis of paraneoplastic autoimmune retinopathy. The patient was treated with oral steroids and mycophenolate mofetil for 1 year. However, there was no improvement in the subjective symptoms or ophthalmologic findings. Conclusions This case of paraneoplastic autoimmune retinopathy in a young man with a history of testicular cancer highlights an early clinical presentation of the disease. It is crucial to recognize that the initial clinical presentation of autoimmune retinopathy can be nonspecific.