南予医学雑誌　第18巻

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南予医誌　Vol.18　No. １　2017－80－Although it cannot be ruled out that inter-ruption of chemotherapy because of lower gastrointestinal bleeding partly contributed to a worse outcome， there is a possibility that BCR-ABL TKD mutations resistant to dasatinib were still at a low level at this point．However， it would have been desir-able to analyze BCR-ABL TKD mutations at least during relapse in order to select the optimal TKI．It has been reported that 26％ of patients treated with dasatinib develop bleeding and that ８％ of those patients suffer gastro-intestinal bleeding， which is classified as grade３-５in ６％ of them 13）．Gastrointes-tinal bleeding is thought to occur through inhibition of platelet-derived growth factor receptor（PDGFR）kinase13）．Although ponatinib has also been reported to inhibit platelet function through its activity against multiple kinases， the incidence of bleeding is reported to be 11％， which is less fre-quent than with dasatinib14）．Accordingly， in the present case， switching to ponatinib when intolerable bleeding occurred after administration of dasatinib was thought to have been effective not only for salvage che-motherapy but also for reducing the risk of bleeding．However， careful observation is needed during the administration of TKIs because the mechanism responsible for the bleeding has not been completely clarified and the various TKIs are associated with a number of adverse cardiovascular effects with different rates of occurrence15）．The optimal type of salvage chemotherapy for patients with resistant or intolerance to imatinib or dasatinib has not yet been fully clarified．Some previous reports have documented that allogenic stem cell transplantation（allo-SCT）can improve the survival of patients with Ph＋MPAL who have achieved CR and subsequently relapsed１，16，17）．However， the treatment options for patients who are ineligible for allo-SCT have not yet been established．Our present patient demonstrated a favor-able short-term clinical course．Although our experience suggests that ponatinib and prednisolone without intensive chemother-apy might also have limitations for mainte-nance of long-term remission， it might still be very useful as a salvage chemotherapy．To our knowledge， this is the rst report of a patient with relapsed Ph＋MPAL who was able to obtain a rapid mCR with a combina-tion of ponatinib and prednisolone．On the other hand， Kawajiri et al．５）have reported that a change of second-generation TKI ac-cording to the BCR-ABL TKD mutations present， and low-dose chemotherapy with vincristine and prednisolone， were effective and safe for an elderly patient with relapsed Ph＋ MPAL．Although further studies are needed， these reports suggest that ponatinib plus prednisolone， or their use in combination with low-dose chemotherapy， could be a useful treatment option for el-derly patients with relapsed Ph＋MPAL．In conclusion， we have described a case of relapsed Ph＋MPAL with imatinib and dasatinib intolerance that was treated suc-cessfully with ponatinib and prednisolone．Ponatinib and prednisolone might be a safe