An open-label, single-arm, multi-center, phase II clinical trial of single-dose [131I]meta-iodobenzylguanidine therapy for patients with refractory pheochromocytoma and paraganglioma

Abstract Objective In this phase II study, we aimed to investigate the efficacy and safety of single-dose [131I]meta-iodobenzylguanidine (131I-mIBG) therapy in patients with refractory pheochromocytoma and paraganglioma (PPGL). Patients and methods This study was designed as an open-label, single-arm, multi-center, phase II clinical trial. The enrolled patients were administered 7.4 GBq of 131I-mIBG. Its efficacy was evaluated 12 and 24 weeks later, and its safety was monitored continuously until the end of the study. We evaluated the biochemical response rate as the primary endpoint using the one-sided exact binomial test based on the null hypothesis (≤ 5%). Results Seventeen patients were enrolled in this study, of which 16 were treated. The biochemical response rate (≥ 50% decrease in urinary catecholamines) was 23.5% (90% confidence interval: 8.5–46.1%, p = 0.009). The radiographic response rates, determined with CT/MRI according to the response evaluation criteria in solid tumors (RECIST) version 1.1 and 123I-mIBG scintigraphy were 5.9% (0.3%–25.0%) and 29.4% (12.4%–52.2%), respectively. The most frequent non-hematologic treatment-emergent adverse events (TEAEs) were gastrointestinal symptoms including nausea, appetite loss, and constipation, which were, together, observed in 15 of 16 patients. Hematologic TEAEs up to grade 3 were observed in 14 of 16 patients. No grade 4 or higher TEAEs were observed. All patients had experienced at least one TEAE, but no fatal or irreversible TEAEs were observed. Conclusion A single dose 131I-mIBG therapy was well tolerated by patients with PPGL, and statistically significantly reduced catecholamine levels compared to the threshold response rate, which may lead to an improved prognosis for these patients.

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Dual immune checkpoint blockade in advanced well-differentiated neuroendocrine tumors, a phase II clinical trial.

Journal of Clinical Oncology ◽

10.1200/jco.2021.39.15_suppl.e16201 ◽

2021 ◽

Vol 39 (15_suppl) ◽

pp. e16201-e16201

Author(s):

Susan Combs Scott ◽

Ana De Jesus-Acosta ◽

Chen Hu ◽

Benjamin Philip Levy ◽

Valsamo Anagnostou ◽

...

Keyword(s):

Clinical Trial ◽

Neuroendocrine Tumors ◽

Phase Ii ◽

Median Duration ◽

Primary Endpoint ◽

Response Rate ◽

Objective Response ◽

Phase Ii Clinical Trial ◽

Open Label ◽

Well Differentiated

e16201 Background: Limited systemic treatment options are available for progressive well-differentiated neuroendocrine tumors (NET), also called carcinoid tumors. Given emerging evidence for immunotherapy response in high grade NET including small cell lung cancer, we sought to determine the efficacy of combination immunotherapy with ipilimumab and nivolumab in patients with advanced, progressive, well-differentiated NET in an open label phase II clinical trial. Methods: Eligible patients had well-differentiated, nonfunctional NET of lung, pancreas, or GI origin that had progressed within the past 12 months after at least one line of prior therapy. Patients received nivolumab 240 mg every 2 weeks and ipilimumab 1mg/kg every 6 weeks for up to 2 years. Primary endpoint was objective response rate (ORR) by RECIST v1.1. Using a Simon’s 2-stage design, the study planned to accrue up to 56 patients. Based on published response rates to everolimus of 5%, we hypothesized that this regimen would be considered promising if the true ORR is > 15%. Results: Nine patients were enrolled prior to study closure due to funding, including 6 patients with NET of lung origin, 2 pancreatic, and 1 small bowel (Table). Median age was 71 years. All patients had distant metastatic disease at enrollment, with an average of 2 prior lines of therapy. Four of 9 patients achieved the primary endpoint of confirmed objective response, all of whom have ongoing response with a median duration of 15.4 months. Five of 9 patients, including all 4 responders, experienced immune-related toxicity requiring treatment modification or discontinuation. The trial did not accrue the target of 56 patients, however, objective response in 4 of 9 patients (ORR 44.4%, 90% CI: 16.9-74.9%) excluded the response rate target (15%). Conclusions: The impressive ORR of 44% with a median duration of response exceeding 15 months in this small clinical trial warrants further study of combination CTLA-4 and PD-1 inhibition in previously treated well-differentiated NET. Our ongoing immunologic and genomic correlative analysis in responders and non-responders will help inform future study of immunotherapy in this patient population in need of new systemic therapy approaches. Clinical trial information: NCT03420521. [Table: see text]

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