Sunitinib as Second-Line Metastatic Renal Cell Carcinoma Treatment

In ESMO Open, Enrique Grande, MD, and collaborating researchers published findings from the IMMUNOSUN trial on the safety and efficacy of sunitinib as a pure second-line treatment for patients with metastatic renal cell carcinoma (mRCC). They felt that, despite the IMMUNOSUN trial not reaching the prespecified endpoint, “it demonstrated that sunitinib is active and can be safely used as a second-line option in patients with mRCC who progress to new standard ICI-based regimens.”

The authors had designed the phase 2 trial to help inform second-line treatment selection guidelines for patients who progressed to ICI-based treatments. They noted that IMMUNOSUN is one of few trials to have evaluated a single tyrosine kinase inhibitor (TKI) after ICI-based therapy failure in mRCC.

The phase 2 single-arm trial was conducted at 10 centers within the Spanish Oncology Genitourinary Group (SOGUG). Participants had a confirmed diagnosis of mRCC with a clear-cell component who had progressed to first-line immune checkpoint inhibitor (ICI)-based regimens. All patients received once-daily oral sunitinib 50 mg for 4 weeks, followed by a 2-week rest period, as per package instructions. The primary endpoint of the trial was the objective response rate.

Second-Line Metastatic Renal Cell Carcinoma Treatment Data

A total of 21 patients were included in the final analyses. Reportedly, all patients showed partial responses, 4 (19.0%) patients achieved objective responses (95% CI, 2.3%-35.8%), and 14 (67%) patients had a stable response, leading the authors to report a clinical benefit for 18 (85.7%) patients (95% CI, 70.7%-100%). Among the 4 objective response patients, the median response duration was 7.1 months (IQR: 4.2-12.0), median progression-free survival (PFS) was 5.6 months (95% CI, 3.1-8.0), and median overall survival was 23.5 months (95% CI, 6.3-40.7). Additionally, the investigators observed that patients with better antitumor responses to first-line ICI-based therapies exhibited longer PFS and OS with sunitinib treatment.

Regarding safety, the most frequent treatment-emergent adverse events were diarrhea (52%), dysgeusia (38%), palmar-plantar erythrodysesthesia (38%), and hypertension (38%). One patient experienced grade 5 pancytopenia, 11 patients experienced grade 3 adverse events, 8 patients had serious adverse events, of which four were judged to be treatment-related.

The article noted that the study was limited by its uncontrolled design, a heterogenous distribution of first-line treatments, the small sample size, and lack of patients with prior ICI+TKI-based treatments.

Regardless, the authors considered the efficacy “remarkable,” though they reported that median PFS appeared shorter than with alternatives in the same setting. Overall, the authors concluded that sunitinib seems to mirror the efficacy of first-line treatment, and that safety signals were consistent with experience during first-line treatment.

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