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nilotinib is an aminophenylpyrimidine - derived tyrosine kinase inhibitor ( tki ) with a selective effect against abl tyrosine kinase , and it now constitutes one of the key drugs of molecular targeting therapy for bcr - abl - positive leukemia .
one significant adverse effect of nilotinib is an elevation of the pancreatic enzyme levels , with reported frequencies spanning from 1.7% to 17.6% ( 1 - 7 ) .
however , it remains unclear as to whether or not this phenomenon has any practical implications , i.e. , this ultimately leads to symptomatic pancreatitis . at the present time ,
an almost total lack of relevant cases has made it difficult to resolve this issue , thus catching physicians off - guard .
two cases of nilotinib - induced acute pancreatitis are herein presented that provide some reasons to reconsider this issue .
case 1 : a 74-year - old man was referred to our institution after it was noticed that he had marked leukocytosis [ white blood cell ( wbc ) : 38.110/l ] in a screening examination .
a complete blood count showed an increased wbc of 32.910/l with relative myeloid hypertrophy , a left shift , and no blasts ( myelocytes : 2% , metamyelocytes : 5% , neutrophils : 77% , eosinophils : 2% , basophils : 1% , lymphocytes : 8% , monocytes : 5% ) . the hemoglobin ( hb ; 126
iu / l ) and lipase ( 33 u / l , normal range : 17 - 57
a bone marrow examination showed marked hypercellularity ( nucleated cell counts : 83.610/l ) with increased megakaryocytes ( 310 /l ) .
no increase in the number of blasts or dysplasia was observed . karyotyping by g - banding technique demonstrated 46,xy , t(9;22)(q34;q11.2 ) in 20 of 20 cells .
a diagnosis of chronic myeloid leukemia ( cml ) in the chronic phase ( cp ) was made , and nilotinib 600 mg / day was started .
on the third day of nilotinib , the patient developed epigastric pain ( grade 2 according to ctcae ver .
laboratory examinations showed marked increases in the pancreatic amylase ( 206 iu / l , grade 4 ) and lipase ( 326 u / l , grade 4 ) levels .
computed tomography ( ct ) revealed swelling of the pancreatic tail , which was compatible with acute pancreatitis .
because he had no other causes of pancreatitis including hypertriglyceridemia , biliary tract obstruction , alcohol intake or diabetes mellitus , nilotinib was considered responsible for the pancreatitis and thus was immediately stopped .
thereafter , his condition improved promptly , with a resolution of the epigastric pain and normalization of pancreatic enzymes .
case 2 : a 73-year - old man presented to our hospital to undergo an investigation of leukocytosis ( 29.710/l ) with a high platelet level ( 114.910/l ) that were discovered during routine check - ups for a past myocardial infarction .
a bone marrow examination revealed hypercellular marrow ( nucleated cell counts : 42.810/l ) with increased megakaryocytes ( 868 /l ) and a myeloid - prone maturation .
cml - cp was diagnosed , and nilotinib 300 mg / day was started . on the fifth day ,
laboratory data showed elevated pancreatic amylase ( 295 /l , grade 4 ) and lipase ( 487 u / l , grade 4 ) levels .
abdominal ct showed swelling of the pancreas head but no sign of bile duct obstruction .
this patient was considered to have nilotinib - induced acute pancreatitis , because he had no history of pancreatitis , excessive alcohol intake , hyperlipidemia or biliary tract disease . although he had been considered to have diabetes , sitagliptin provided good control ( hba1c 6.3% ) .
nilotinib was stopped and the epigastric pain immediately subsided followed by the normalization of the pancreatic enzyme levels .
his tki was switched to dasatinib , and there has been no recurrence of pancreatitis . both of these cases are presented in figure .
clinical courses of the two cases , a ) case 1 and b ) case 2 , are presented .
the dotted line indicates the upper normal limit of pancreatic amylase ( p - amy ) .
an elevation of pancreatic enzymes has been recognized as a major adverse event of nilotinib ( 1,3 - 7 ) , but a clear description of the cases with symptomatic pancreatitis has been lacking .
a total of 32 cases of pancreatitis have been reported to the japanese adverse drug event report database of pmda since nilotinib was introduced 7 years ago , but lack of any detailed data of these cases made the true association unclear .
the incidence of pancreatitis in nilotinib - treated patients is estimated to be 0.28% judging from post - marketing surveillance data ( 2 cases of pancreatitis and 7 cases of acute pancreatitis were reported out of a total of 3,234 cases ) .
both of the present cases featured a short latency from drug administration to the onset of acute pancreatitis , and this is consistent with badalov 's criteria for drug - induced acute pancreatitis which classified suspicious drugs according to the level of evidence , and the consistency of latency among reported cases is a key factor to support the etiological influence of this drug ( 8) . the mechanism of tki - induced pancreatitis is not known , but it can be deduced by the presumed mechanism of elevation of the pancreatic enzyme levels by nilotinib , which includes pancreatic cell damage through inhibition of non - receptor type tyrosine kinase c - abl , and interference with pathways that regulate the exocrine secretion of pancreatic enzymes ( 9 ) . a hypertriglyceridemia - mediated mechanism should also be considered , because hypertriglyceridemia is often seen as an adverse effect of nilotinib , and it is a well - known risk factor for pancreatitis , accounting for up to 7% of all pancreatitis cases ( 10 ) .
however , the threshold for triglycerides to induce acute pancreatitis is considered to be relatively high , generally over 1,500 mg / dl ( 11 ) , and neither of the present patients showed this level of elevation .
abdominal pain , usually constant and located in the epigastrium , is one of the most typical symptoms of acute pancreatitis ( 9 ) .
the observation of this symptom in our patients drove us to proceed to detailed examinations , leading to the diagnosis of acute pancreatitis .
it is noteworthy that the drug information sheet for nilotinib states that epigastric pain is commonly seen , with a reported incidence of 9.3% in japan ( 12 ) .
for example , gastric mucosal damage due to an increased level of serum histamine is a common symptom of chronic myeloid leukemia especially in the early treatment phase with massive residual disease , and thus presents as epigastric pain .
we are concerned that acute pancreatitis is relegated to the bottom of the list when making a differential diagnosis because of the incorrect preconception that nilotinib does not cause pancreatitis .
considering the critical significance of the initial response in cases of acute pancreatitis , we can not put enough emphasis on the need to suspect this etiology when encountering a case demonstrating epigastric pain . in the present cases , it was possible to successfully diagnose and deal with drug - induced pancreatitis , although we can not completely rule out hyperhistaminemia as the cause of epigastric pain because the histamine levels were not measured . in conclusion ,
nilotinib can cause not only a simple elevation of the pancreatic enzyme levels , but also clinically significant pancreatitis .
further investigation is therefore required to determine the precise incidence , background characteristics , and risk factors underlying the symptomatic pancreatitis induced by nilotinib .
nilotinib is a selective tyrosine kinase inhibitor for the treatment of philadelphia chromosome - positive leukemias . 
 an elevation of the pancreatic enzyme level is one of the major adverse events associated with nilotinib , but whether or not nilotinib induces symptomatic pancreatitis remains to be elucidated . 
 the cases of two chronic myeloid leukemia patients treated with nilotinib who developed symptomatic acute pancreatitis on the third and fifth day of nilotinib administration are herein presented . 
 since both patients had no other etiologies for pancreatitis , nilotinib was considered to be the causal agent . 
 the withdrawal of nilotinib resulted in a prompt recovery . 
 these cases underline the importance of recognizing pancreatitis as a possible adverse event associated with nilotinib .