Outstanding Response to Sorafenib in a Patient with Metastatic Gastrointestinal Stromal Tumour

Gastrointestinal stromal tumour (GIST) is the most common sarcoma and can be seen in any part of the gastrointestinal tract. The effect of tyrosine kinase inhibitors varies with mutation status in receptor tyrosine kinase KIT and in platelet-derived growth factor receptor A (PDGFRA). This case presents a 61-year-old man, diagnosed with an 11-cm GIST located at the stomach with a high risk of recurrence. The patient showed intolerance to imatinib shortly after introduction and subsequently progressed on sunitinib and nilotinib. The patient started fourth-line treatment with sorafenib with an impressive response to a point at which metastases intra-abdominally and in the liver could be resected. After surgery, sorafenib was restarted. Due to toxicity, sorafenib dose was reduced over time. The dose was insufficient to control the disease since a new recurrence was detected. Mutation analyses revealed a GIST harbouring a deletion of codon p.I843_D846del, located at PDGFRA exon 18, right next to the codon D842 where mutations are known leading to imatinib resistance. In this case, the GIST was highly sensitive to sorafenib, and the response was dose related. It is mandatory to perform mutation analyses on primary tumour and at recurrence in the decision-making of the correct treatment for the patient. In March 2021, the patient had been in treatment with sorafenib for 12.5 years and was still without signs of recurrence. A multidisciplinary approach was essential for the long-term survival of the patient in this case.

Ethnicity is important for creatinine excretion among Inuit and Caucasians in Greenland

BACKGROUND

Human nutrition, contamination and renal function are commonly assessed by the analysis of urine. A complete 24-hour urine sample is the ideal but it is inconvenient and unreliable. Thus, spot urine sampling with creatinine adjustment is widely used. Stratification for age and gender is recommended. Still, ethnicity may influence creatinine excretion.

METHODS

We collected 104 24-h urine samples among Inuit and non-Inuit living in Greenland. Completeness of sampling was checked by using para-amino benzoic acid (PABA) that also allowed for compensation of creatinine excretion when sampling was incomplete. We measured creatinine using the Jaffe method and PABA by the HPLC method.

RESULTS

Participants were recruited from the capital city, a major town and a settlement (n = 36/48/20). They were aged 30-69 years with 78 Inuit and 26 non-Inuit. Inuit were smaller than non-Inuit (Caucasians): height, 163 vs. 177 cm, p < 0.001; weight, 71 vs. 84 kg, p = 0.001 with similar BMI. Creatinine excretion was lower in Inuit compared to non-Inuit (men, 1344/1807 mg/24 h; women 894/1259 mg/24 h; p = 0.002; 0.02). It was influenced by age (p < 0.001), gender (p < 0.001), weight (p = 0.001) and ethnicity (p = 0.030) while not by the intake of the protein-rich Inuit diet in the adjusted analysis. Creatinine excretion was described by: Inuit men, 1925 mg - (13.1 × age); Inuit women, 1701 mg - (17.0 × age).

CONCLUSION

Inuit and Caucasians have different creatinine excretion. It is recommended to stratify by ethnicity in addition to adjustment for age and gender when using creatinine correction of spot urine samples.