Key Points Question Do contemporary first-line therapy options for metastatic renal cell carcinoma (mRCC) have different likelihoods of objective imaging response (complete or partial response), and is objective imaging response associated with overall survival? Findings In this cohort study involving 899 patients with mRCC, treatment with immune checkpoint blockade plus vascular endothelial growth factor receptor inhibitor combination therapies was more likely to be associated with objective imaging response than doublet immune checkpoint blockade therapy after adjustment for baseline demographic and clinical characteristics, including International Metastatic Renal Cell Carcinoma Database Consortium risk criteria. Objective imaging response was associated with improvement in overall survival among patients receiving both types of therapy. Meaning This study’s findings suggest that combination therapies with first-line immune checkpoint blockade plus vascular endothelial growth factor receptor inhibitor were more likely to be associated with objective imaging response than doublet immune checkpoint blockade therapy.

NTRK gene fusions are rare oncogenic driver mutations that can be found in a broad range of neoplasms. In secretory carcinoma (SC), ETV6-NTRK3 gene fusion is seen in a majority of the cases and represents a druggable target for patients with advanced disease in the absence of a currently accepted standard of care. In our case, we describe a patient with recurrent, metastatic SC treated with first line entrectinib with clinically meaningful, durable ongoing response after 49 months. The patient experienced grade 1 fatigue, dysgeusia, skin sensitivity, arthralgias, an increase in serum creatinine, and weight-gain as well as grade 2 hypotension which resolved after a dose reduction. Entrectinib is a well-tolerated treatment with the potential for durable responses and TRK inhibition should be considered the standard of care in SC and other NTRK gene fusion-positive advanced neoplasms without acceptable alternative treatment options.

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318 Background: There are limited data to understand the activity of cabozantinib (CABO) as second line (2L) therapy post standard of care ipilimumab-nivolumab (IPI-NIVO) or immuno-oncology(IO)/vascular endothelial growth factor (VEGF) inhibitor combinations (IOVE). The activity of subsequent 3L approved therapies post CABO has not been established. Methods: Using the IMDC dataset, we examined all patients who received 2L CABO. We sought to identify the overall response rate (ORR), time to treatment failure (TTF) and overall survival (OS) of 2L CABO after IPI-NIVO, approved IOVE combinations and other 1L approaches. Additionally, we examined these outcomes for patients that received an approved 3L treatment post 2L CABO. Hazard ratios were adjusted for IMDC risk groups. Results: 346 patients were identified who had all received 2L CABO (78 post 1L IPI NIVO, 46 post 1L IOVE, 222 post 1L other). Of the entire cohort, 12.6%, 62.6% and 24.8% were IMDC favourable, intermediate and poor risk, respectively. 84% had clear cell histology, 18.5% had a sarcomatoid component and 38.3% had bone metastases at diagnosis. Outcomes for patients that received 2L CABO, stratified by 1L therapy are outlined in the table, followed by outcomes for patients that received subsequent 3L therapy post 2L CABO. After adjustment for IMDC criteria, the HR for 2L CABO OS and TTF for IOVE vs IPI-NIVO were 1.73 (95% CI 0.83-3.62 p = 0.14) and 1.62 (0.89-2.95 p = 0.11), respectively. Conclusions: There is clinically meaningful activity of CABO post IPI-NIVO, IOVE and other standard 1L approved therapies. Broadly, time to event endpoints and response rates are similar irrespective of 1L therapy. Approved systemic therapies post CABO, mainly single agent VEGF inhibitors also have activity, though as expected this is diminished compared to earlier lines of therapy. These are real world benchmarks with which to counsel our patients when using single agent CABO.[Table: see text]