Disclosures Mara B. Antonoff reports a consulting or advisor role at AstraZeneca, Bristol Myers Squibb, Ethicon, and Merck. Brendon M. Stiles reports personal honoraria or consulting fees from AstraZeneca, Bristol Myers Squibb, Genentech/Roche, Regeneron, Pfizer, Gala Therapeutics, Medtronic, and Merck; patents, royalties, and other intellectual property related to a therapeutic antibody targeting ART1, an extracellular mono-ADP ribosyltransferase, for the treatment of cancer, patent application filed; uncompensated membership on the scientific advisory boards of the Lung Cancer Research Foundation and LUNGevity; and an indirect relationship by association with SIGA Technologies through his spouse, who is a SIGA Technologies employee and stockholder. Both other authors declare that they have no conflicts of interest to disclose.