Corrigendum: Clinical Utilization Pattern of Liquid Biopsies (LB) to Detect Actionable Driver Mutations, Guide Treatment Decisions and Monitor Disease Burden During Treatment of 33 Metastatic Colorectal Cancer (mCRC) Patients (pts) at a Fox Chase Cancer Center GI Oncology Subspecialty Clinic.

[This corrects the article DOI: 10.3389/fonc.2018.00652.].

Dual Checkpoint Inhibition with Ipilimumab plus Nivolumab After Progression on Sequential PD-1/PDL-1 Inhibitors Pembrolizumab and Atezolizumab in a Patient with Lynch Syndrome, Metastatic Colon, and Localized Urothelial Cancer.

Immune checkpoint blockade (ICB) is an approved therapy for advanced metastatic mismatch repair (MMR)-deficient cancer regardless of tissue of origin. Although therapy is effective initially, recurrence rates are significant, and long-term outcomes remain poor for most patients. It is not currently recommended to give sequential ICB for advanced MMR-deficient colorectal cancer (CRC) or for patients with metastatic cancer from Lynch syndrome. The need for subsequent therapy options in advanced MMR-deficient cancer beyond the first ICB regimen arises in clinical practice, and there are often no effective standard chemotherapies or other targeted therapies. We report the case of a Lynch syndrome patient with metastatic CRC and urothelial cancer who was treated sequentially with pembrolizumab (targeting PD1), atezolizumab (targeting PD-L1), brief rechallenge with pembrolizumab, and finally the combination of ipilimumab (targeting CTLA-4) and nivolumab (targeting PD1). Over a 28-month period the patient experienced prolonged disease control with each different regimen the first time it was given, including metabolic response by positron emission tomography and computed tomography scanning and tumor marker reductions. The case suggests that some patients with advanced MMR-deficient CRC may experience meaningful clinical benefit from multiple sequential ICB regimens, a strategy that can be further tested in clinical trials. KEY POINTS: The case exemplifies clinical benefit from sequential immune checkpoint blockade in a patient with Lynch syndrome with advanced metastatic colorectal cancer and urothelial cancer.Metabolic response, with decreased fluorodeoxyglucose avidity on positron emission tomography and computed tomography, and reductions in tumor markers, such as carcinoembryonic antigen, were helpful in this case to monitor disease status over a 28-month period of therapy.The concept of sequential immune checkpoint blockade in patients with advanced mismatch repair-deficient cancer merits further study to determine which patients are most likely to benefit.

Clinical Utilization Pattern of Liquid Biopsies (LB) to Detect Actionable Driver Mutations, Guide Treatment Decisions and Monitor Disease Burden During Treatment of 33 Metastatic Colorectal Cancer (mCRC) Patients (pts) at a Fox Chase Cancer Center GI Oncology Subspecialty Clinic.

Background: Liquid biopsy (LB) captures dynamic genomic alterations (alts) across metastatic colorectal cancer (mCRC) therapy and may complement tissue biopsy (TB). We sought to describe the utility of LB and better understand mCRC biology during therapy. Methods: Thirty-three patients (pts) with mCRC underwent LB. We used permutation-based t-tests to assess associations between alts, and clinical variables and used Kendall's tau to measure correlations. Results: Of 33 pts, 15 were women; 22 had colon, and the rest rectal cancer. Pts received a median of two lines of therapy before LB. Nineteen pts had limited testing on TB (RAS/RAF/TP53/APC), 11 extended NGS, and 3 no TB. Maxpct and alts correlated with CEA (p < 0.001, respectively). In 3/5 pts with serial LB, CEA correlated with maxpct trend, and CT tumor burden. In 6 pts, mutant RAS was seen in LB and not TB; 5/6 had received anti-EGFR therapy prior to LB, suggesting RAS alts developed post-therapy. In two pts RAS-mutated by TB, no RAS alts were detected on LB; these pts had low disease burden on CT at time of LB that also did not reveal APC or TP53 alts. In six patients who were KRAS wt based on TB, post anti-EGFR LB revealed subclonal KRAS mutations, likely a treatment effect. The median number of alts was higher post anti-EGFR LB (n = 12) vs. anti-EGFR naïve LB (n = 22) (9.5 vs. 5.5, p = 0.059) but not statistically significant. More alts were also noted in post anti-EGFR therapy LB vs. KRAS wt anti-EGFR-naïve LB (n = 6) (9.5 vs. 5) among patients with KRAS wild-type tumors, although the difference was not significant (p = 0.182). Conclusions: LB across mCRC therapy detects driver mutations, monitors disease burden, and identifies sub-clonal alts that reflect drug resistance, tumor evolution, and heterogeneity. Interpretation of LB results is impacted by clinical context.