Alternative schedules or integration strategies to maximise treatment duration with sunitinib in patients with gastrointestinal stromal tumours

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.

Personalization of regorafenib treatment in metastatic gastrointestinal stromal tumours in real-life clinical practice

Background:

Regorafenib (REG) has now been approved as the standard third-line therapy in metastatic gastrointestinal stromal tumour (GIST) patients at the recommended dose and schedule of 160 mg once daily for the first 3 weeks of each 4-week cycle. However, it has a relevant toxicity profile that mainly occurs within the first cycles of therapy, and dose and schedule adjustments are often required to reduce the frequency or severity of adverse events and to avoid early treatment discontinuation. To date, large amounts of data on the use of REG in metastatic GIST patients in daily clinical practice are not available, and we lack information about how this treatment personalization really affects the quality of life (QoL) of patients. The aim of the present retrospective study is to build a comprehensive picture of all alternative REG strategies adopted in daily clinical practice for use in metastatic GIST patients.

Methods:

Metastatic GIST patients treated with dose adjustment or alternative schedules of REG at seven reference Italian centres were retrospectively included.

Results:

For a total of 62 metastatic GIST patients, we confirmed that REG treatment adjustment is common in clinical practice and that it is very heterogeneous, with approximately 20 different strategies being adopted. Independent of which strategy is chosen, treatment personalization has led to a clinical benefit defined as complete or partial resolution of side effects in almost all patients, affecting the duration of REG treatment.

Conclusions:

The personalization of REG, even if it is heterogeneous, seems to be crucial to maximize the overall treatment duration.

Population Pharmacokinetic/Pharmacodynamic Modeling of Sunitinib by Dosing Schedule in Patients with Advanced Renal Cell Carcinoma or Gastrointestinal Stromal Tumor

Background

Sunitinib is a multi-targeted tyrosine kinase inhibitor used in the treatment of advanced renal cell carcinoma (RCC) and imatinib-resistant/intolerant gastrointestinal stromal tumors (GIST).

Methods

A meta-analysis of 10 prospective clinical studies in advanced RCC and GIST was performed to support the development of pharmacokinetic (PK) and PK/pharmacodynamic (PD) models that account for the effects of important covariates. These models were used to make predictions with respect to the PK, safety, and efficacy of sunitinib when administered on the traditional 4-weeks-on/2-weeks-off schedule (Schedule 4/2) versus an alternative schedule of 2 weeks on/1 week off (Schedule 2/1).

Results

The covariates found to have a significant effect on one or more of the PK or PD parameter studies included, age, sex, body weight, race, baseline Eastern Cooperative Oncology Group performance status, tumor type, and dosing schedule. The models predicted that, in both RCC and GIST patients, Schedule 2/1 would have comparable efficacy to Schedule 4/2, despite some differences in PK profiles. The models also predicted that, in both indications, sunitinib-related thrombocytopenia would be less severe when sunitinib was administered on Schedule 2/1 dosing compared with Schedule 4/2.

Conclusion

These findings support the use of sunitinib on Schedule 2/1 as a potential alternative to Schedule 4/2 because it allows for the management of toxicity without loss of efficacy.

Electronic supplementary material

The online version of this article (doi:10.1007/s40262-016-0404-5) contains supplementary material, which is available to authorized users.

Successful treatment with personalized dosage of imatinib in elderly patients with gastrointestinal stromal tumors

Imatinib is the standard first-line therapy for metastatic gastrointestinal stromal tumors. It has markedly improved the prognosis and outcome of patients affected by gastrointestinal stromal tumors, especially in the case of exon 11 KIT mutations. Imatinib-associated adverse events are generally mild to moderate; however, in clinical practice, intolerance caused by chronic toxicities frequently leads to breaks in treatment. This is particularly true in elderly patients in whom age, decline in drug metabolism, and polypharmacy, with a possible drug-drug interaction, may influence the tolerability of imatinib. In the present article, we report our extensive experience with the management of imatinib therapy in a 'real' population, in particular in very elderly patients, discussing whether the use of personalized imatinib dosage could be a safe and advantageous option, enabling continuous administration, thus ensuring effective treatment. Only a few case reports in the literature provide data on outcome with low tailored dosage of imatinib and none of them has been carried out on a Western population. Here, we report four cases treated with low imatinib dosage as a safe and useful option enabling continued treatment with imatinib, improving tolerance, and maintaining good and lasting disease control.