Purpose In 2016, ASCO published a guideline to assist in clinical decision making in metastatic pancreatic cancer for initial assessment after diagnosis, first- and second-line treatment options, palliative and supportive care, and follow-up. The purpose of this update is to incorporate new evidence related to second-line therapy for patients who have experienced disease progression or intolerable toxicity during first-line therapy. Methods ASCO convened an Expert Panel to conduct a systematic review of the literature on second-line therapy published between June 2015 and January 2018. Recommendations on other topics covered in the 2016 Metastatic Pancreatic Cancer Guideline were endorsed by the Expert Panel. Results Two new studies were found that met the inclusion criteria. Recommendations For second-line therapy, gemcitabine plus nanoparticle albumin-bound paclitaxel should be offered to patients with first-line treatment with FOLFIRINOX (leucovorin, fluorouracil, irinotecan, and oxaliplatin), an Eastern Cooperative Oncology Group performance status (ECOG PS) of 0 to 1, and a favorable comorbidity profile; fluorouracil plus nanoliposomal irinotecan can be offered to patients with first-line treatment with gemcitabine plus NAB-paclitaxel, an ECOG PS of 0 to 1, and a favorable comorbidity profile; fluorouracil plus irinotecan or fluorouracil plus oxaliplatin may be offered when there is a lack of availability of fluorouracil plus nanoliposomal irinotecan; gemcitabine or fluorouracil should be offered to patients with either an ECOG PS of 2 or a comorbidity profile that precludes other regimens. Testing select patients for mismatch repair deficiency or microsatellite instability is recommended, and pembrolizumab is recommended for patients with mismatch repair deficiency or high microsatellite instability tumors. Endorsed recommendations from the 2016 version of this guideline for computed tomography, baseline performance status and comorbidity profile, defining goals of care, first-line therapy, and palliative care are also contained within the full guideline text. Additional information is available at www.asco.org/gastrointestinal-cancer-guidelines .