Abstract
Purpose
Streptozocin (STZ) is a key agent for treating advanced pancreatic neuroendocrine tumors (pNET). Most STZ regimens for pNET are daily and also include 5-fluorouracil (5FU), whereas STZ monotherapy and weekly regimens have also been applied in daily practice in Japan. The present study aimed to evaluate responses to weekly regimens and to STZ monotherapy, and to identify a predictive marker of a response to STZ.
Methods
Clinical data regarding STZ-based chemotherapy for pNET were collected between 2015 and 2017 at 25 facilities. We analyzed the effects, safety, progression-free survival (PFS), and factors that correlate with responses to STZ.
Results
The overall objective response rate (ORR) of 110 patients who underwent STZ-based chemotherapy (monotherapy, 81.8%; weekly regimen 46.4%) was 21.8%, and PFS was 9.8 months. The ORR of weekly vs. daily regimens was 21.6 vs. 22.0% (P = 1.000), and that of monotherapy vs. combination therapy was 21.1 vs. 25.0% (P = 0.766). A Ki67 proliferation index (Ki67) of > 5% was a predictive marker of a response to STZ (P = 0.017), whereas regimen type, mono- or combination therapy, treatment line and liver tumor burden were not associated with responses. The frequencies of Grade ≥ 3 nausea and hematological adverse events were significantly lower for monotherapy than combination therapy (P = 0.032).
Conclusions
The effects of weekly STZ monotherapy on pNET are comparable to those previously reported and the toxicity profile was acceptable. Ki67 > 5% was the sole predictive marker of an objective response.
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Acknowledgements
We are grateful to Drs. Yuichi Tachibana, Nozomu Machida, and Yutaka Kawano for cooperation and helpful discussions.
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This work received no outside funding.
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Author Masafumi Ikeda has received research grants from Ono Pharmaceutical, AstraZeneca, Taiho Pharmaceutical, Merck Serono, Yakult, Kyowa Hakko Kirin, Eisai, Eli Lilly Japan, Baxter, ASLAN Pharmaceuticals, Chugai Pharmaceutical; speaker honoraria from Bayer Yakuhin, Taiho Pharmaceutical, Novartis Pharma, Bristol-Myers Squibb, Eli Lilly Japan. Author Susumu Hijioka has received speaker honoraria from Novelpharma, Novartis Pharma and Teijin Pharma. Author Hiroshi Imaoka has received a speaker honorarium from Novartis Pharma. The other authors have no conflicts of interest to declare.
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All procedures involving human participants proceeded in accordance with the ethical standards of each institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Formal consent is not required for this type of study.
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Informed consent was obtained from all individual participants included in the study.
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Shibuya, H., Hijioka, S., Sakamoto, Y. et al. Multi-center clinical evaluation of streptozocin-based chemotherapy for advanced pancreatic neuroendocrine tumors in Japan: focus on weekly regimens and monotherapy. Cancer Chemother Pharmacol 82, 661–668 (2018). https://doi.org/10.1007/s00280-018-3656-y
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DOI: https://doi.org/10.1007/s00280-018-3656-y
Keywords
- Pancreatic neuroendocrine tumor
- Streptozocin
- Monotherapy
- Prognostic factor
- Ki67 proliferation index