Highly variable timing renders immunotherapy efficacy and toxicity impractical biomarkers of one another in clinical practice.

Background: A useful clinical biomarker requires not only association but also a consistent temporal relationship. For instance, chemotherapy-induced neutropenia and epidermal growth-factor inhibitor-related acneiform rash both occur within weeks of treatment initiation, thereby providing information prior to efficacy assessment. Although immune checkpoint inhibitor (ICI)-associated immune-related adverse events (irAE) have been associated with therapeutic benefit, irAE may have delayed and highly variable onset. To determine whether ICI efficacy and irAE could serve as clinically useful biomarkers for predicting each other, we determined the temporal relationship between initial efficacy assessment and irAE onset in a diverse population treated with ICI. Methods: Using two-sided Fisher exact and Cochran-Armitage tests, we determined the relative timing of initial efficacy assessment and irAE occurrence in a cohort of 155 ICI-treated patients (median age 68 years, 40% women). Results: Initial efficacy assessment was performed a median of 50 days [interquartile range (IQR) 39-59 days] after ICI initiation; median time to any irAE was 77 days (IQR 28-145 days) after ICI initiation. Median time to first irAE was 42 days (IQR 20-88 days). Overall, 58% of any irAE and 47% of first irAE occurred after initial efficacy assessment. For clinically significant (grade ≥2) irAE, 60% of any and 53% of first occurred after initial efficacy assessment. The likelihood of any future irAE did not differ according to response (45% for complete or partial response vs. 47% for other cases; P=1). In landmark analyses controlling for clinical and toxicity follow-up, patients demonstrating greater tumor shrinkage at initial efficacy assessment were more likely to develop future grade ≥2 (P=0.05) and multi-organ (P=0.02) irAE. Conclusions: In contrast to that seen with chemotherapy and molecularly targeted therapies, the temporal relationship between ICI efficacy and toxicity is complex and bidirectional. In practice, neither parameter can be routinely relied on as a clinical biomarker to predict the other.

The phosphatidylserine targeting antibody bavituximab plus pembrolizumab in unresectable hepatocellular carcinoma: a phase 2 trial.

Immune checkpoint inhibitors targeting PD-1/L1 have modest efficacy in hepatocellular carcinoma as single agents. Targeting membranous phosphatidylserine may induce pro-inflammatory and -immune stimulating effects that enhance immunotherapy activity. This hypothesis was tested in a single-arm phase 2 trial evaluating frontline bavituximab, a phosphatidylserine targeting antibody, plus pembrolizumab (anti-PD-1) in patients with unresectable hepatocellular carcinoma (NCT03519997). The primary endpoint was investigator-assessed objective response rate among evaluable patients, and secondary end points included progression-free survival, incidence of adverse events, overall survival, and duration of response. Among 28 evaluable patients, the confirmed response rate was 32.1%, which met the pre-specified endpoint, and the median progression-free survival was 6.3 months (95% CI, 1.3-11.3 months). Treatment related-adverse events of any grade occurred in 45.7% of patients, with grade 3 or greater adverse events in 14.3% of patients. Adverse events of any cause were observed in 33 patients (94.3%), with grade 3 or greater adverse events in 11 patients (31.4%). Prespecified exploratory analyses of baseline tumor specimens showed that a depletion of B cells, and the presence of fibrotic tissue and expression of immune checkpoints in stroma was associated with tumor response. These results suggest that targeting phosphatidylserine may lead to synergistic effects with PD-1 blockade without increasing toxicity rates, and future studies on this therapeutic strategy may be guided by biomarkers characterizing the pre-treatment tumor microenvironment.

Pathologic response and surgical outcomes in patients undergoing nephrectomy following receipt of immune checkpoint inhibitors for renal cell carcinoma.

OBJECTIVE: To evaluate the pathologic response, safety, and feasibility of nephrectomy following receipt of immune checkpoint inhibition (ICI) for renal cell carcinoma (RCC). METHODS: Patients who underwent nephrectomy for RCC after exposure to nivolumab monotherapy or combination ipilimumab/nivolumab were reviewed. Primary surgical outcomes included operative time (OT), estimated blood loss (EBL), length of stay (LOS), readmission rates, and complication rates. Pathologic response in the primary and metastatic sites constituted secondary outcomes. RESULTS: Eleven nephrectomies (10 radical, 1 partial) were performed in 10 patients after ICI with median postoperative follow-up 180 days. Six patients received 1 to 4 cycles of ipilimumab/nivolumab, while 5 received 2 to 12 infusions of nivolumab preoperatively. Five surgeries were performed laparoscopically, and 4 patients underwent concomitant thrombectomy. One patient exhibited complete response (pT0) to ICI, and 3/4 patients who underwent metastasectomy for hepatic, pulmonary, or adrenal lesions exhibited no detectable malignancy in any of the metastases resected. No patients experienced any major intraoperative complications, and all surgical margins were negative. Median OT, EBL, and LOS were 180 minutes, 100 ml, and 4 days, respectively. Four patients experienced a complication, including 3 that were addressed with interventional radiology procedures. One patient died of progressive disease >3 months after surgery, and 1 patient succumbed to pulmonary embolism complicated by sepsis. No complications or readmissions were noted in 6 patients. CONCLUSION: Nephrectomy following ICI for RCC is safe and technically feasible with favorable surgical outcomes and pathologic response. Timing of the nephrectomy relative to checkpoint dosing did not seem to impact outcome. Biopsies of lesions responding radiographically to ICI may warrant attention prior to surgical excision.