The Evolution of Immune Checkpoint Inhibitors in Advanced Urothelial Carcinoma

A phase II study of retifanlimab, a humanized anti-PD-1 monoclonal antibody, in patients with solid tumors (POD1UM-203)

BACKGROUND

POD1UM-203, an open-label, multicenter, phase II study, evaluated retifanlimab, a humanized monoclonal antibody targeting programmed cell death protein-1 (PD-1) in patients with selected solid tumors where immune checkpoint inhibitor therapies have previously shown efficacy.

PATIENTS AND METHODS

Eligible patients (≥18 years) had measurable disease and included unresectable or metastatic melanoma, treatment-naive metastatic non-small-cell lung cancer (NSCLC) with high programmed death-ligand 1 (PD-L1) expression (tumor proportion score ≥50%), cisplatin-ineligible locally advanced/metastatic urothelial carcinoma (UC) with PD-L1 expression (combined positive score ≥10%), or treatment-naive locally advanced/metastatic clear-cell renal cell carcinoma (RCC). Retifanlimab 500 mg was administered intravenously every 4 weeks as a 30-min infusion. The primary endpoint was investigator-assessed overall response rate.

RESULTS

Overall, 121 patients (35 melanoma, 23 NSCLC, 29 UC, 34 RCC) were enrolled and treated. The overall response rate [95% confidence interval (CI)] was 40.0% (23.9-57.9) in the melanoma cohort, 34.8% (16.4-57.3) in the NSCLC cohort, 37.9% (20.7-57.7) in the UC cohort, and 23.5% (10.7-41.2) in the RCC cohort. Median duration of response was 11.5 months (95% CI 2.2-not reached) in the UC cohort, and was not reached in the other cohorts. Retifanlimab safety was consistent with previous experience for PD-(L)1 inhibitors.

CONCLUSIONS

Retifanlimab demonstrated durable antitumor activity in patients with melanoma, NSCLC, UC, or RCC. The efficacy and safety of retifanlimab were as expected for a PD-(L)1 inhibitor. These data support further study of retifanlimab in solid tumors.

Cutoff values of PD-L1 expression in urinary cytology samples for predicting response to immune checkpoint inhibitor therapy in upper urinary tract urothelial carcinoma

BACKGROUND

The objective of this study was to determine the cutoff value of PD-L1 expression that can predict response to immune checkpoint inhibitor (ICI) immunotherapy for upper tract urothelial carcinoma (UTUC).

METHODS

The concordance of PD-L1 expression between paired surgical resection specimens (SRSs) and urine cell blocks (UCBs) (cohort 1) was studied in a retrospective set of 58 UTUC patients to determine its suitability as a predictor of ICI immunotherapy efficacy. PD-L1 expression in UCBs obtained before neoadjuvant ICI immunotherapy was verified in a prospective set of 12 UTUC patients (cohort 2). PD-L1 (SP263 clone) expression was assessed for percentage (tumor proportional score) of tumor cell (TC) showing PD-L1 staining.

RESULTS

The authors found an overall agreement of 94.4% (51 of 54) between UCBs and SRSs in cohort 1 (positive percent agreement = 100%, negative percent agreement = 93.8%, r value = 0.63). PD-L1 expression in <10% and ≥10% of tumor cells (TCs) of UCBs were the best predictors of negative (<25%) and positive (≥25%) expression in TCs of SRSs, respectively (concordance = 98.1%, r value = 0.93). These findings were verified in cohort 2: at the 10% cutoff for PD-L1 expression, the best response predictive value was 83.3% (5 of 6) in PD-L1-positive patients, and the nonresponse predictive value was 50% (3 of 6) in PD-L1-negative patients. The sensitivity, specificity, and area under the receiver operating characteristic curve values for predicting ICI immunotherapy efficacy based on PD-L1-expressing TCs in UCBs were 62.5%, 75%, and 0.688, respectively.

CONCLUSIONS

Immunocytochemistry of UCBs is reliable for determining PD-L1 expression, which can predict the efficacy of ICI immunotherapy at a cutoff of 10%.

The Association between a Decrease in On-Treatment Neutrophil-to-Eosinophil Ratio (NER) at Week 6 after Ipilimumab Plus Nivolumab Initiation and Improved Clinical Outcomes in Metastatic Renal Cell Carcinoma

A lower baseline neutrophil-to-eosinophil ratio (NER) has been associated with improved responses to immune checkpoint inhibitors (ICI)-treated metastatic renal cell carcinoma (mRCC). This study investigated the decrease in NER at week 6 after ipilimumab/nivolumab (ipi/nivo) initiation and treatment responses in mRCC. A retrospective study of ipi/nivo-treated mRCC at two US academic cancer centers was conducted. A landmark analysis at week 6 was performed to assess the association between the change in NER and clinical responses (progression-free survival (PFS)/overall survival (OS)). Week 6 NER was modeled as a continuous variable, after log transformation (Ln NER), and a categorical variable by percent change. There were 150 mRCC patients included: 78% had clear cell histology, and 78% were IMDC intermediate/poor risk. In multivariable regression analysis, every decrease of 1 unit of Ln NER at week 6 was associated with improved PFS (adjusted hazard ratio (AHR): 0.78, p-value:0.005) and OS (AHR: 0.67, p-value: 0.002). When NER was modeled by percent change, decreased NER > 50% was associated with improved PFS (AHR: 0.55, p-value: 0.03) and OS (AHR: 0.37, p-value: 0.02). The decrease in week 6 NER was associated with improved PFS/OS in ipi/nivo-treated mRCC. Prospective studies are warranted to validate NER change as a biomarker to predict ICI responses.