Clinical activity of CC-90011, an oral, potent, and reversible LSD1 inhibitor, in advanced malignancies.

BACKGROUND: CC-90011 is an oral, potent, selective, reversible inhibitor of lysine-specific demethylase 1 (LSD1) that was well tolerated, with encouraging activity in patients who had advanced solid tumors or relapsed/refractory marginal zone lymphoma. The authors present long-term safety and efficacy and novel pharmacodynamic and pharmacokinetic data from the first-in-human study of CC-90011. METHODS: CC-90011-ST-001 (ClincalTrials.gov identifier NCT02875223; Eudract number 2015-005243-13) is a phase 1, multicenter study in which patients received CC-90011 once per week in 28-day cycles. The objectives were to determine the safety, maximum tolerated dose, and/or recommended phase 2 dose (primary) and to evaluate preliminary efficacy and pharmacokinetics (secondary). RESULTS: Sixty-nine patients were enrolled, including 50 in the dose-escalation arm and 19 in the dose-expansion arm. Thrombocytopenia was the most common treatment-related adverse event and was successfully managed with dose modifications. Clinical activity with prolonged, durable responses were observed, particularly in patients who had neuroendocrine neoplasms. In the dose-escalation arm, one patient with relapsed/refractory marginal zone lymphoma achieved a complete response (ongoing in cycle 58). In the dose-expansion arm, three patients with neuroendocrine neoplasms had stable disease after nine or more cycles, including one patient who was in cycle 46 of ongoing treatment. CC-90011 decreased levels of secreted neuroendocrine peptides chromogranin A, progastrin-releasing peptide, and RNA expression of the blood pharmacodynamic marker monocyte-to-macrophage differentiation-associated. CONCLUSIONS: The safety profile of CC-90011 suggested that its reversible mechanism of action may provide an advantage over other irreversible LSD1 inhibitors. The favorable tolerability profile, clinical activity, durable responses, and once-per-week dosing support further exploration of CC-90011 as monotherapy and in combination with other treatments for patients with advanced solid tumors and other malignancies.

Phase I Study of Lysine-Specific Demethylase 1 Inhibitor, CC-90011, in Patients with Advanced Solid Tumors and Relapsed/Refractory Non-Hodgkin Lymphoma.

PURPOSE: Lysine-specific demethylase 1 (LSD1) is implicated in multiple tumor types, and its expression in cancer stem cells is associated with chemoresistance. CC-90011 is a potent, selective, and reversible oral LSD1 inhibitor. We examined CC-90011 in advanced solid tumors and relapsed/refractory (R/R) non-Hodgkin lymphoma (NHL). PATIENTS AND METHODS: CC-90011-ST-001 (NCT02875223; 2015-005243-13) is a phase I, multicenter, first-in-human dose-escalation study. Nine dose levels of CC-90011 (1.25-120 mg) given once per week were explored. Primary objectives were to determine safety, maximum tolerated dose (MTD), and/or recommended phase II dose (RP2D). Secondary objectives were to evaluate preliminary efficacy and pharmacokinetics. RESULTS: Fifty patients were enrolled, 49 with solid tumors (27 neuroendocrine tumors/carcinomas) and 1 with R/R NHL. Median age was 61 years (range, 22-75). Patients received a median of three (range, 1-9) prior anticancer regimens. The RP2D was 60 mg once per week; the nontolerated dose (NTD) and MTD were 120 mg once per week and 80 mg once per week, respectively. Grade 3/4 treatment-related toxicities were thrombocytopenia (20%; an on-target effect unassociated with clinically significant bleeding), neutropenia (8%; in the context of thrombocytopenia at the highest doses), and fatigue (2%). The patient with R/R NHL had a complete response, currently ongoing in cycle 34, and 8 patients with neuroendocrine tumors/carcinomas had stable disease ≥6 months, including bronchial neuroendocrine tumors, kidney tumor, and paraganglioma. CONCLUSIONS: CC-90011 is well tolerated, with the RP2D established as 60 mg once per week. The MTD and NTD were determined to be 80 mg once per week and 120 mg once per week, respectively. Further evaluation of CC-90011 is warranted.

The Mnks: MAP kinase-interacting kinases (MAP kinase signal-integrating kinases).

The human MAP kinase-interacting kinases (or MAP kinase signal-integrating kinases), Mnks, comprise a group of four proteins derived from two genes (Gene symbols: MKNK1 and MKNK2) by alternative splicing. Mnk1a/b differ at their C-termini, as do Mnk2a/2b: in each case, the a-form possesses a longer C-terminal region than the b-form, which lacks the MAP kinase-binding region. The N-termini of all forms contain a polybasic region which binds importin a and the translation factor scaffold protein eukaryotic initiation factor (eIF) 4G. The catalytic domains of Mnk1a/b and Mnk2a/b share three unusual features: two short inserts and a DFD feature where other kinases have DFG. Mnk isoforms differ markedly in their activity and regulation, and in subcellular localization. The best-characterised Mnk substrate is eIF4E. The cellular role of eIF4E phosphorylation remains unclear: it may promote export of certain mRNAs from the nucleus. Other Mnk substrates bind to AU-rich elements that modulate the stability/translation of specific mRNAs. Mnks may also control production of inflammatory mediators and signaling from tyrosine kinase receptors, as well as cell proliferation or survival.

The Drosophila protein kinase LK6 is regulated by ERK and phosphorylates the eukaryotic initiation factor eIF4E in vivo.

In Drosophila cells, phosphorylation of eIF4E (eukaryotic initiation factor 4E) is required for growth and development. In Drosophila melanogaster, LK6 is the closest homologue of mammalian Mnk1 and Mnk2 [MAPK (mitogen-activated protein kinase) signal-integrating kinases 1 and 2 respectively] that phosphorylate mammalian eIF4E. Mnk1 is activated by both mitogen- and stress-activated signalling pathways [ERK (extracellular-signal-regulated kinase) and p38 MAPK], whereas Mnk2 contains a MAPK-binding motif that is selective for ERKs. LK6 possesses a binding motif similar to that in Mnk2. In the present study, we show that LK6 can phosphorylate eIF4E at the physiological site. LK6 activity is increased by the ERK signalling pathway and not by the stress-activated p38 MAPK signalling pathway. Consistent with this, LK6 binds ERK in mammalian cells, and this requires an intact binding motif. LK6 can bind to eIF4G in mammalian cells, and expression of LK6 increases the phosphorylation of the endogenous eIF4E. In Drosophila S2 Schneider cells, LK6 binds the ERK homologue Rolled, but not the p38 MAPK homologue. LK6 phosphorylates Drosophila eIF4E in vitro. The phosphorylation of endogenous eIF4E in Drosophila cells is increased by activation of the ERK pathway but not by arsenite, an activator of p38 MAPK. RNA interference directed against LK6 significantly decreases eIF4E phosphorylation in Drosophila cells. These results show that LK6 binds to ERK and is activated by ERK signalling and it is responsible for phosphorylating eIF4E in Drosophila.