Utility and optimal management of planned drug holidays during lenvatinib treatment in patients with unresectable differentiated thyroid cancer: a real-world multi-center study

PURPOSE

Lenvatinib achieves favorable therapeutic outcomes for patients with radioactive iodine therapy refractory differentiated thyroid cancer (DTC); however, its use is associated with a high incidence of adverse events. To avoid severe adverse events, planned drug holidays (PDH) have been proposed. This study aimed to evaluate treatment effects, identify prognostic factors, and investigate the usefulness of PDH in patients with unresectable DTC who received lenvatinib across the multi-institutions.

METHODS

Fifty-one patients with unresectable DTC treated with lenvatinib were evaluated retrospectively. Overall survival (OS) and progression-free survival (PFS) were calculated, and prognostic factors were assessed. OS, PFS, and time to treatment failure (TTF) were compared between patients with and without PDH. Lenvatinib administration schedule was evaluated in PDH.

RESULTS

The 3-year OS and PFS rate were 53.5% and 42.1%, respectively. Multivariate analysis revealed that presence of maximum size of lung metastasis ≥10 mm was independent prognostic factor for poorer OS and PFS, and histology other than papillary thyroid carcinoma was the independent prognostic factor for poorer PFS. Twenty-five patients (49%) treated with PDH. There were significant differences in OS, PFS, and TTF between patients with and without PDH. Various schedules were used in PDH. Eight (32%) patients required switch to the different administration schedule.

CONCLUSION

Our results suggest that PDHs may extend OS, PFS, and TTF. In patients with PDH, various schedules used for lenvatinib administration highlight the difficulty in determining a uniform administration schedule. Therefore, it is crucial to consider the optimal lenvatinib administration schedule on a case-by-case basis.

Advances in the molecular mechanism and targeted therapy of radioactive-iodine refractory differentiated thyroid cancer

Most patients with differentiated thyroid cancer have a good prognosis after radioactive iodine-131 treatment, but there are still a small number of patients who are not sensitive to radioiodine treatment and may subsequently show disease progression. Therefore, radioactive-iodine refractory differentiated thyroid cancer treated with radioiodine usually shows reduced radioiodine uptake. Thus, when sodium iodine symporter expression, basolateral membrane localization and recycling degradation are abnormal, radioactive-iodine refractory differentiated thyroid cancer may occur. In recent years, with the deepening of research into the pathogenesis of this disease, an increasing number of molecules have become or are expected to become therapeutic targets. The application of corresponding inhibitors or combined treatment regimens for different molecular targets may be effective for patients with advanced radioactive-iodine refractory differentiated thyroid cancer. Currently, some targeted drugs that can improve the progression-free survival of patients with radioactive-iodine refractory differentiated thyroid cancer, such as sorafenib and lenvatinib, have been approved by the FDA for the treatment of radioactive-iodine refractory differentiated thyroid cancer. However, due to the adverse reactions and drug resistance caused by some targeted drugs, their application is limited. In response to targeted drug resistance and high rates of adverse reactions, research into new treatment combinations is being carried out; in addition to kinase inhibitor therapy, gene therapy and rutin-assisted iodine-131 therapy for radioactive-iodine refractory thyroid cancer have also made some progress. Thus, this article mainly focuses on sodium iodide symporter changes leading to the main molecular mechanisms in radioactive-iodine refractory differentiated thyroid cancer, some targeted drug resistance mechanisms and promising new treatments.

Lenvatinib Therapy for Advanced Thyroid Cancer: Real-life Data on Safety, Efficacy and Some Rare Side Effects

Context

The SELECT trial led to the approval of lenvatinib for the treatment of advanced radioiodine-refractory differentiated thyroid carcinomas (DTCs) but also revealed an important adverse event (AE) profile which may limit its use in clinical practice.

Objective

We aim to describe the efficacy and toxicity profiles of lenvatinib in real life.

Methods

We included all patients who received lenvatinib for an advanced DTC at our institution, enrolling 27 patients. We reviewed retrospectively electronic medical records to assess efficacy and AEs.

Results

Among the 24 patients with evaluation of tumor response during treatment, overall response rate (ORR) was 37.0% (95% CI, 19.4%-57.6%), and disease control rate was 85.2% (95% CI, 66.3%-95.8%). The median progression-free survival (PFS) was 12 months (95% CI, 7.5-16.5]. The most prevalent AEs were hypertension (77.8%), fatigue (55.6%), and weight loss (51.9%). At least one grade ≥ 3 AE was experienced by 25/27 patients (92.6%), mostly hypertension (59.3%). Lenvatinib was discontinued due to AEs in 13/27 patients (48.1%). Interestingly, 1 patient experienced a grade 4 posterior reversible encephalopathy syndrome, and another developed a Takotsubo cardiomyopathy.

Conclusion

The safety profile of lenvatinib in our cohort was similar to that reported in the literature, with a predominance of hypertension. Rigorous blood pressure control is therefore essential to avoid discontinuing therapy. We also report 2 severe and rarely described AEs that physicians should watch for. As for efficacy, although less than in the SELECT trial, ORR and PFS were similar to other real-life studies.

Management of VEGFR-Targeted TKI for Thyroid Cancer

Recent advances in the development of multitarget tyrosine kinase inhibitors (MTKIs), which mainly target the vascular endothelial growth factor receptor (VEGFR), have improved prognoses and dramatically changed the treatment strategy for advanced thyroid cancer. However, adverse events related to this inhibition can interrupt treatment and sometimes lead to discontinuation. In addition, they can be annoying and potentially jeopardize the subjects' quality of life, even allowing that the clinical outcome of patients with advanced thyroid cancer remains limited. In this review, we summarize the potential mechanisms underlying these adverse events (hypertension, proteinuria and renal impairment, hemorrhage, fistula formation/gastrointestinal perforation, wound healing, cardiovascular toxicities, hematological toxicity, diarrhea, fatigue, and acute cholecystitis), their characteristics, and actual management. Furthermore, we also discuss the importance of related factors, including alternative treatments that target other pathways, the necessity of subject selection for safer administration, and patient education.