Clinical benefit of sunitinib in gastrointestinal stromal tumors with different exon 11 mutation genotypes

English version of Japanese Clinical Practice Guidelines 2022 for gastrointestinal stromal tumor (GIST) issued by the Japan Society of Clinical Oncology

The Japan Society of Clinical Oncology Clinical Practice Guidelines 2022 for gastrointestinal stromal tumor (GIST) have been published in accordance with the Minds Manual for Guideline Development 2014 and 2017. A specialized team independent of the working group for the revision performed a systematic review. Since GIST is a rare type of tumor, clinical evidence is not sufficient to answer several clinical and background questions. Thus, in these guidelines, we considered that consensus among the experts who manage GIST, the balance between benefits and harms, patients' wishes, medical economic perspective, etc. are important considerations in addition to the evidence. Although guidelines for the treatment of GIST have also been published by the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO), there are some differences between the treatments proposed in those guidelines and the treatments in the present guidelines because of the differences in health insurance systems among countries.

Sunitinib versus imatinib dose escalation after failure of imatinib standard dose in patients with advanced Gastrointestinal stromal tumors - a real-world multi-center study

BACKGROUND

Whether to escalate imatinib dosage or directly switch to sunitinib in gastrointestinal stromal tumors (GISTs) failing on standard dose 400 mg/d of imatinib is still controversial.

METHODS

We evaluated progression-free survival (PFS), overall survival (OS), and time to sunitinib failure (TTSF) of patients selecting imatinib dose escalation or directly switching to sunitinib after the failure of imatinib 400 mg/d therapy from 3 tertery referring centers between January 2008 to December 2016.

RESULTS

A total of 240 patients receiving sunitinib (37.5 mg continuous daily dose or 50 mg 4 weeks on with 2 weeks off) for at least 8 weeks were examined. After failure on imatinib 400 mg/d, 100 (49.3%) patients had dose escalation to 600 mg or 800 mg per day (IM group, imatinib group), and 103 (50.7%) directly switched to sunitinib (SU group, sunitinib group). The PFS in the SU and IM groups was 12 months and 5.0 months (P < 0.001), respectively. TTSF or OS in both groups was not statistically significantly different.

CONCLUSIONS

After the progression of imatinib standard-dose treatment in recurrent/metastatic GISTs, the PFS of patients directly switching to sunitinib was significantly longer compared with the PFS of patients with imatinib dose escalation. However, when the patients continued with sunitinib therapy after the failure of IM dose escalation, TTSF and OS in the IM group were similar to those in the SU group. Further exploration of the characteristics of the population benefiting from imatinib dose escalation are warranted.

Clinical outcomes of imatinib dose escalation versus sunitinib in first-line imatinib-failure gastrointestinal stromal tumour

AIM

The majority of available data on the clinical efficacy of sunitinib in patients with imatinib-resistant or -intolerant gastrointestinal stromal tumours (GISTs) are from studies of western populations. We investigated the clinical outcomes of imatinib dose escalation versus sunitinib in first-line imatinib-failure Asian GIST patients to further guide clinical treatment.

METHODS

Patients received imatinib dose escalation and a shift to sunitinib (Group A) or a direct shift to sunitinib (Group B). The objective tumour response was assessed according to Choi's criteria. Progression-free survival (PFS) and overall survival (OS) were calculated. The relationship between genetic mutation and survival was analysed.

RESULTS

In total, 40 patients who fulfilled the inclusion criteria were recruited. The differences in survival between Group A and Group B were not significant for PFS (p = .776) or OS (p = .219). For patients with KIT exon 11 mutation, a trend towards a better PFS was found in Group B (p = .122), OS of Group B was better than Group A (p = .013). The median PFS and OS of sunitinib treatment were 8 and 24 months, respectively, and a clinical benefit was observed in 80%. Patients with KIT exon 11 mutations had better PFS compared to those with KIT exon 9 mutations or wild-type GISTs (p = .017, p = .040, respectively).

CONCLUSIONS

Both imatinib dose escalation and sunitinib were optional in Asian patients after failure of first-line imatinib, and patients with KIT exon 11 mutation benefited more from a direct shift to sunitinib.

Complete response to sunitinib for more than three years in a patient with a jejunum gastrointestinal stromal tumor: A case report

RATIONALE

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract and is characterized by KIT mutations. Patientsresistant to 1st-line imatinib therapy are usually given sunitinib assecond-line treatment, which provides a median progression-free survival of 8 to 12 months. We report the 1st case of metastatic jejunum GIST with a KIT exon 11 deletion that showed complete response (CR) to sunitinib for more than 3 years.

PATIENT CONCERNS

A 34-year-old man with advanced jejunum GIST was surgically treated upon initial diagnosis, and was histologically found to carry a high recurrence risk. Genetic testing revealed a KIT exon 11 deletion, and adjuvant therapy with imatinib was administered. The imatinib dose was escalated following recurrence in the abdomen, but the mass continued to grow.

DIAGNOSIS

He was diagnosed with abdominal recurrence of GIST based on his medical history and histopathological results.

INTERVENTION

Second-line sunitinib therapy was given.

OUTCOMES

The mass disappeared, and CR was seen following 7 months of sunitinib therapy; this CR was sustained for more than 45 months.

LESSONS

In cases of metastatic jejunum GIST with a KIT exon 11 deletion, sunitinib as second-line therapy can be used to achieve CR for more than 3 years.