INNOVATIVE AGENTS AND TREATMENT MODALITIES: Edited by Ahmad Awada and Steven T. RosenTargeting molecular subtypes in solid cancers: successes and failuresAssi, Ritaa; Kotecki, Nuriab; Awada, AhmadbAuthor Information aDepartment of Internal Medicine, Division of Hematology-Oncology, Lebanese American University Medical Center, Rizk Hospital, Beyrouth, Lebanon bOncology Medicine Department, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium Correspondence to Ahmad Awada, Oncology Medicine Department, Institut Jules Bordet, Université Libre de Bruxelles, Rue Héger-Bordetstraat 1, B-1000 Brussel, Belgium. Tel: +32 0 2 541 31 89, 541 32 38; fax: +32 0 2 541 33 39; e-mail: firstname.lastname@example.org Current Opinion in Oncology: September 2020 - Volume 32 - Issue 5 - p 488-493 doi: 10.1097/CCO.0000000000000670 Buy Metrics Abstract Purpose of review We herein review some of the major patterns of resistance and lessons learned from the use of earlier targeted therapies in two genotype-driven solid tumors. Recent findings Targeted agents have rapidly expanded in the field of oncology over the past 2 decades. The breakthroughs achieved by these agents have been, however, hindered by the inevitable development of drug resistance. Intrinsic or acquired mechanisms of resistance eventually lead to treatment tolerance and tumoral plasticity with phenotypic switch and evasion of the original targeted pathway. Failures in such therapies also result from poor selectivity of the target, drug delivery, and unaffordable costs. Summary Based on above findings, collaborative efforts are advancing at the molecular level to design better drugs or combinatorial strategies and to develop more sensitive assays to monitor responses and the emergence of resistance. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.