Exceptional response to chemotherapy followed by concurrent radiotherapy and immunotherapy in a male with primary retroperitoneal serous Adenocarcinoma: a case report and literature review.

BACKGROUND: Primary retroperitoneal serous adenocarcinoma (PRSA) is an extremely uncommon malignancy exclusively reported in females. Due to the rarity of the disease, it is difficult to establish a standardized treatment. CASE PRESENTATION: We describe a unique case of PRSA in a 71-year-old male who presented with right-sided lower back pain and numbness. Magnetic resonance imaging identified a mass invading the adjacent psoas muscle and twelfth rib. Tissue biopsy confirmed poorly differentiated PRSA. Patient was initially treated with neoadjuvant carboplatin and paclitaxel chemotherapy regimen. This resulted in complete radiological resolution of the tumor. However, 12 weeks later, rapid recurrence was noted on follow-up CT scan. The patient was then treated with external radiotherapy with concurrent nivolumab, an anti-PD-1 antibody. The patient displayed a positive response to treatment with reduction in primary tumor and metastases and had a sustained disease control. CONCLUSION: Treatment with radiotherapy in combination with anti-PD-1 antibody could be an effective modality of management for PRSA.

Differentiation Syndrome in a Patient With NSCLC Harboring IDH2 Mutation Treated With Enasidenib: Case Report.

IDH2 gain-of-function mutations cause DNA hypermethylation interfering with cellular differentiation and are linked to poor disease outcomes in NSCLC. IDH2-inhibitor enasidenib is approved for refractory acute myeloid leukemia but has been associated with delayed onset of differentiation syndrome-a potentially fatal inflammatory reaction caused by differentiating agents, namely all-trans retinoic acid and arsenic trioxide. We report the first case of differentiation syndrome in a patient with NSCLC treated with enasidenib, who after 7 weeks experienced bilateral peripheral edema and shortness of breath, with scans exhibiting pericardial effusion and ground-glass opacities suggestive of pneumonitis. Differentiation syndrome should be considered as a differential diagnosis in patients with solid tumors undergoing IDH2-inhibitor targeted therapy.

Clinical and Immunological Implications of Frameshift Mutations in Lung Cancer.

INTRODUCTION: Presently, programmed death ligand 1 is the most commonly used biomarker to predict response to immune checkpoint inhibitors (ICIs) in NSCLC. Owing to its several limitations, there is continuous search for more precise and reliable markers. Frameshift mutations by insertion or deletion (fsindels) are suggested to induce more immunogenic tumor-specific neoantigens, conferring better response to ICIs. Positive correlation of fsindels with ICI response has been studied in melanoma and renal cell carcinoma. We investigated the implication of fsindels in the clinical outcomes and immune landscape of patients with NSCLC treated with ICIs. METHODS: We utilized The Cancer Genome Atlas data set to analyze tumor mutational burden, neoantigen burden, and immune landscape in relation to fsindel status. In addition, utilizing the clinical data from 122 patients treated with ICIs, we evaluated the influence of fsindels on disease response rates and survival outcomes. RESULTS: A positive correlation between fsindel burden and tumor mutational burden and activated CD4/CD8 T-cell infiltration was shown. Presence of fsindels was also associated with significant prolongation of progression-free survival in patients treated with ICIs (median 6.2 versus 2.7 months [p = 0.01]). In addition, significant differences in the overall response rates (26% versus 12% [p = 0.04]) and disease control rates (68% versus 48% [p = 0.02]) were observed in patients with fsindels. CONCLUSION: Our findings suggest that fsindels may have a predictive role for ICI response in NSCLC.