Outcome of Restarted Sunitinib Treatment in Patients with Metastatic Renal Cell Carcinoma: a Retrospective Trial and Combined Case Reports from Literature

In practice it is still not clear whether a drug holiday in sunitinib (Su) treatment can be safety, without impairing the overall outcome of patients with metastatic renal cell carcinoma (mRCC). The aim was to retrospectively evaluate the outcome in patients who restarted Su after an interruption of ≥3 months and a combined analysis of case studies from literature. From 556 patients treated between January 2006 and March 2016 a group of 38 patients were selected whose treatment was interrupted for other reasons than disease progression. During interruption Su was restarted in case of RECIST-defined progression. The primary objective was the objective response (OR) and progression free survival (PFS) of baseline and restarted therapy. The secondary objective was the overall survival (OS) calculated from the start of baseline treatment. Multivariate survival analysis was also applied. The major causes of interruption were toxicity (39%) and patient' choice (24%). Median duration of interruption was 7 (range 3-41) months. The OR of baseline and restarted treatment was 63% and 39%, respectively. After a median follow-up of 76 (95% CI 65-79) months the median PFS of baseline and restarted treatment was 21 (18-27) and 14 (10-18) months, respectively. The median OS was 61 (56-80) months. In multivariate analysis the lack of OR of restated treatment was an independent predictor of shorter PFS of restarted Su. According to our findings and also on combined case studies from literature restarted Su can be effective in selected cases of patients who progressed during treatment holiday.

Tyrosine kinase inhibitors rechallenge in solid tumors: a review of literature and a case description with lenvatinib in thyroid cancer

INTRODUCTION

In the last decade tyrosine kinase inhibitors (TKIs) have been employed for a wide range of hematological and solid tumors and today they represent a valid therapeutic option for different neoplasms. Among them, both sorafenib and lenvatinib were approved for the treatment of radioactive iodine (RAI) refractory differentiated thyroid carcinoma (DTC). Unfortunately, in some cases the efficacy of TKIs is limited by the onset of drug resistance after the initial response. Areas covered: We report the case of a patient with a RAI refractory advanced DTC, treated with lenvatinib after surgery, multiple RAI administrations, traditional chemotherapy, and sorafenib. During treatment with lenvatinib, a noticeable response was detected by sequential computed tomography scans but, after 27 months, tumor progression became evident and led to lenvatinib interruption. In absence of any active treatment, a further disease progression was documented, and lenvatinib was re-administered obtaining a new objective response. Starting from this case report, we review available reports about the rechallenge with TKIs in solid tumors, discussing the possible mechanisms underlying the efficacy of this approach. Expert commentary: Rechallenge with TKIs in solid tumors could be a therapeutic option in subjects with advanced and metastatic DTC who experience a progressive disease after initial response to lenvatinib.

The role of rechallenge with targeted therapies in metastatic renal-cell carcinoma

PURPOSE OF REVIEW

To explore the accumulating evidence and feasibility of rechallenge with agents targeting the vascular endothelial growth factor (VEGF) and mammalian target of rapamycin (mTOR) pathways for incorporation into the evolving management algorithm for metastatic renal-cell carcinoma (mRCC).

RECENT FINDINGS

The current standard of care after the development of resistance to first-line targeted therapies in mRCC is sequential treatment with subsequent lines of alternative anti-VEGF agents or mTOR inhibitors, with optimal sequencing being the focus of ongoing research. Recent evidence from case study and retrospective reports suggests that mRCC patients can achieve important clinical benefits from rechallenge at later lines of therapy with the same targeted therapy used for previous line treatment. Further, the results of REchallenge with SUnitinib in MEtastatic, the first study of sunitinib rechallenge to include a prospective component, reinforce the potential for prolonged survival with this treatment approach for mRCC patients.

SUMMARY

Rechallenge represents an important and feasible therapeutic option for the future treatment of mRCC patients. The results of ongoing prospective studies are expected to further evaluate the benefits of rechallenge and better inform wherein this approach fits in the treatment algorithm for mRCC.

Sunitinib re-challenge in advanced renal-cell carcinoma

Despite offering significant clinical benefits in advanced renal-cell carcinoma (RCC), the effectiveness of targeted therapies eventually declines with the development of resistance. Defining optimal sequences of therapy is therefore the focus of much current research. There is also evidence that treatment 're-challenge' may be an effective strategy in some patients. We review evidence to evaluate whether sunitinib may have value as re-challenge therapy in patients who have progressed on prior targeted therapy with sunitinib and/or an alternative tyrosine kinase inhibitor or mammalian target of rapamycin inhibitor. Re-challenge with sunitinib appears to be of clinical benefit, thus representing a feasible therapeutic option for patients with advanced RCC who are refractory to other treatments and are able to receive further therapy. These observations support hypotheses that resistance to targeted agents is transient and can be at least partially reversed by re-introduction of the same agent after a treatment break. Median progression-free survival durations appear to be shorter and response rates lower on re-challenge than following initial treatment, although a wider interval between treatments appears to increase response to sunitinib re-challenge.