Detection of microsatellite instability-high (MSI-H) by liquid biopsy predicts robust and durable response to immunotherapy in patients with pancreatic cancer.

Clinical trials reporting the robust antitumor activity of immune checkpoint inhibitors (ICIs) in microsatellite instability-high (MSI-H) solid tumors have used tissue-based testing to determine the MSI-H status. This study assessed if MSI-H detected by a plasma-based circulating tumor DNA liquid biopsy test predicts robust response to ICI in patients with pancreatic ductal adenocarcinoma (PDAC). Retrospective analysis of patients with PDAC and MSI-H identified on Guardant360 from October 2018 to April 2021 was performed; clinical outcomes were submitted by treating providers. From 52 patients with PDAC +MSI-H, outcomes were available for 10 (19%) with a median age of 68 years (range: 56-82 years); the majority were male (80%) and had metastatic disease (80%). Nine of 10 patients were treated with ICI. Eight out of nine patients received single-agent pembrolizumab (8/9), while one received ipilimumab plus nivolumab. The overall response rate by Response Evaluation Criteria in Solid Tumors was 77% (7/9). The median progression-free survival and overall survival were not reached in this cohort. The median duration of treatment with ICI was 8 months (range: 1-24), and six out of seven responders continued to show response at the time of data cut-off after a median follow-up of 21 months (range: 11-33). Tissue-based MSI results were concordant with plasma-based G360 results in five of six patients (83%) who had tissue-based test results available, with G360 identifying one more patient with MSI-H than tissue testing. These results suggest that detecting MSI-H by a well-validated liquid biopsy test could predict a robust response to ICI in patients with PDAC. The use of liquid biopsy may expand the identification of PDAC patients with MSI-H tumors and enable treatment with ICI resulting in improved outcomes.

Crucial role for ecto-5'-nucleotidase (CD73) in vascular leakage during hypoxia.

Extracellular adenosine has been widely implicated in adaptive responses to hypoxia. The generation of extracellular adenosine involves phosphohydrolysis of adenine nucleotide intermediates, and is regulated by the terminal enzymatic step catalyzed by ecto-5'-nucleotidase (CD73). Guided by previous work indicating that hypoxia-induced vascular leakage is, at least in part, controlled by adenosine, we generated mice with a targeted disruption of the third coding exon of Cd73 to test the hypothesis that CD73-generated extracellular adenosine functions in an innate protective pathway for hypoxia-induced vascular leakage. Cd73(-/-) mice bred and gained weight normally, and appeared to have an intact immune system. However, vascular leakage was significantly increased in multiple organs, and after subjection to normobaric hypoxia (8% O(2)), Cd73(-/-) mice manifested fulminant vascular leakage, particularly prevalent in the lung. Histological examination of lungs from hypoxic Cd73(-/-) mice revealed perivascular interstitial edema associated with inflammatory infiltrates surrounding larger pulmonary vessels. Vascular leakage secondary to hypoxia was reversed in part by adenosine receptor agonists or reconstitution with soluble 5'-nucleotidase. Together, our studies identify CD73 as a critical mediator of vascular leakage in vivo.

Incidence and Predictive Factors for Recovery of Ovarian Function in Amenorrheic Women in Their 40s Treated With Letrozole.

PURPOSE: This prospective study assessed the impact of 2 years of aromatase inhibitor (AI) therapy on the incidence of ovarian function recovery (OFR) in women age 40 to 49 with estrogen receptor-positive breast cancer who were premenopausal at diagnosis and who underwent chemotherapy-induced amenorrhea during adjuvant treatment. PATIENTS AND METHODS: Women age 40 to 49 with estrogen receptor-positive breast cancer who had ceased menstruating with adjuvant cyclophosphamide-based chemotherapy, had postmenopausal serum estradiol (E2), and had received tamoxifen for ≥ 1 year were treated with letrozole (2.5 mg) daily for ≥ 2 years. Serum follicle-stimulating hormone (FSH) and E2 were measured at baseline and over 2 years. A general linear model was used to assess serial FSH by OFR. Logistic regression was used to assess baseline predictors and OFR. RESULTS: The study enrolled 177 women (145 women age 45 to 49 years and 32 women age 40 to 44 years). Of 173 evaluable patients, 67 (39%; 95% CI, 31% to 46%) regained ovarian function; 11 of these patients (6%; 95% CI, 3% to 10%) resumed menses, and 56 of these patients (32%; 95% CI, 25% to 39%) developed premenopausal E2 without menses. Among AI-naïve patients, serial FSH significantly increased over time (P < .001), did not vary significantly by OFR status (P = .55), but showed mild evidence of a decrease after month 12 for those who resumed menses (P = .0989). Age less than 45 years and inhibin B were significant multivariable baseline predictors of OFR. CONCLUSION: These results emphasize the challenge in determining definitive menopause in women with chemotherapy-induced amenorrhea. The risk of OFR during treatment with AIs in amenorrheic women in their 40s is high, and AI therapy should be avoided in these patients.