The median PFS was 4.8 months and the median OS was 10.3 months . how it differs from CM. The results of several studies that have been investigating ICB in metastatic UM are offered. We discuss possible reasons for the lack of effectiveness of ICB in UM compared to CM, focus on the pitfalls of ICB with this malignancy entity, and clarify why additional immune-modulating therapies could still be an option for CP-91149 future UM therapies. gene coding for v-Raf murine sarcoma viral oncogene homolog, and about 20% harbor mutations in the gene coding for neuroblastoma rat CP-91149 sarcoma viral oncogene homolog [14,15,16,17]. Both activating and mutations lead to a constitutive activation of the mitogen-activated protein kinase (MAPK) signaling pathway that promotes proliferation and survival, and therefore contribute to malignancy formation and progression [18,19]. In contrast to CM, the number of mutations in UM is extremely low , and interestingly, standard CM driver mutations are not present in UM and vice versa. Instead of and mutations, which are almost never observed in UM [21,22], more than 80% of all UM harbor mutations in the genes encoding the guanine nucleotide-binding proteins Q polypeptide (GNAQ) and 11 (GNA11) [21,22]. and the closely related encode G subunits of heterotrimeric G-proteins that interact with G-protein-coupled receptors. In about 90% of all instances, codon 209  located in the Ras-like GTPase website of the proteins is definitely affected , and most generally, glutamine is definitely substituted by leucine (Q209L). This blocks the GTPase activity of the enzyme, resulting in a constantly bound GTP and thus a constitutive activation of the PLC/PKC pathway and downstream RAF-MEK-ERK signaling [21,22,25]. Besides, additional downstream pathways as Trio-Rho-Rac and YAP-Hippo get triggered by mutated G proteins . A high PI3K-Akt-mTOR activity is also regularly observed in UM ; however, this seems to be the result of a phosphatase and tensin homolog (PTEN) manifestation loss , rather than due to mutated G proteins [28,29]. Other driver mutations in UM are by far less regularly recognized and involve encoding the G-protein-coupled cysteinyl leukotriene receptor 2 and coding for phospholipase C 4, which take action immediately upstream and downstream of GNAQ/11 in the transmission transduction cascade [20,30,31]. Inactivating mutations in are present in about 40% to 47% of UM main tumors and 80% of UM metastases . BAP1 is definitely a tumor suppressor involved in the restoration of CP-91149 DNA double strand breaks , and about 8% of UM individuals carry BAP1 germline mutations leading to a loss of function . Mutations in genes coding for splicing element 3B, subunit 1 (gene, which is also located on chromosome 3p21.3 , and chromosome 8q amplifications . Metastatic spread of UM happens more often in tumors harboring than mutations [62,63], and mutations are associated with an intermediate risk of metastases and the onset of late-occurring metastases . Among these aberrations, monosomy 3 seems to be the strongest predictor for disease progression . On the other hand, the presence of mutations  and chromosome 6p amplifications [59,61] are associated with a better prognosis. Besides, four molecularly different UM subsets can be defined, which are associated with different medical results . In the metastatic stage, UM therapy offers mainly been used from CM. Once metastases are present, the disease program is definitely often aggressive, and the prognosis remains dismal. A variety of local liver-directed treatment options have been investigated in medical trials, but most of them did not result in a better survival in metastatic disease [65,66]. The regularly happening and mutations that lead to a constitutive activity of the MAPK signaling pathway [21,22] provided the rationale for the use of small molecule inhibitors targeting the downstream kinases. Several inhibitors targeting MEK have already been developed and with trametinib, cobimetinib, and binimetinib, and three of them have been approved for metastatic BRAF-mutated CM in combination with a BRAF inhibitor CP-91149 [67,68,69]. However, a recent systematic review showed that UM is usually little responsive to MEK inhibition regardless of the inhibiting agent and combination partner . For example, the potentially encouraging combination of binimetinib with the PKC inhibitor sotrastaurin showed no clinical efficacy, but a high quantity of patients developed severe adverse events, resulting in the termination of the respective phase Ib/II clinical trial . The MEK inhibitor selumetinib showed promising results in a phase II study compared to chemotherapy, with a response rate of 14% . Thus, the expectations were high that comparable results would be achieved in the SUMIT trial, a prospective double-blind phase CTNND1 III study investigating selumetinib plus dacarbazine versus dacarbazine alone . Unfortunately, disappointing results were observed, as only 3% of the patients responded, and the progression-free.