Pyrotinib combined with thalidomide in advanced non-small-cell lung cancer patients harboring HER2 exon 20 insertions (PRIDE): protocol of an open-label, single-arm phase II trial.

BACKGROUND: Standard therapy for human epidermal growth factor receptor 2 (HER2)-mutant non-small-cell lung cancer (NSCLC) is lacking. The clinical benefits with pan-HER inhibitors (afatinib, neratinib, and dacomitinib), anti-HER2 antibody drug conjugate (ADC) trastuzumab emtansine, and an emerging irreversible tyrosine kinase inhibitor (TKI) poziotinib were modest. Another new ADC trastuzumab deruxtecan showed encouraging outcomes, but only phase I study was completed. Pyrotinib, another emerging irreversible epidermal growth factor receptor (EGFR)/HER2 dual TKI, has been approved in HER2-positive breast cancer in 2018 in China. It has shown promising antitumor activity against HER2-mutant NSCLC in phase II trials, but pyrotinib-related diarrhea remains an issue. The antiangiogenic and immunomodulatory drug thalidomide is a cereblon-based molecular glue that can induce the degradation of the IKAROS family transcription factors IKZF1 and IKZF3. The use of thalidomide can also decrease gastrointestinal toxicity induced by anti-cancer therapy. METHODS: This is an open-label, single-arm phase II trial. A total of 39 advanced NSCLC patients with HER2 exon 20 insertions and ≤ 2 lines of prior chemotherapy will be recruited, including treatment-naïve patients who refuse chemotherapy. Patients are allowed to have prior therapy with immune checkpoint inhibitors and/or antiangiogenic agents. Those who have prior HER2-targeting therapy or other gene alterations with available targeted drugs are excluded. Eligible patients will receive oral pyrotinib 400 mg once daily and oral thalidomide 200 mg once daily until disease progression or intolerable toxicity. The primary endpoint is objective response rate. DISCUSSION: The addition of thalidomide to pyrotinib is expected to increase the clinical benefit in advanced NSCLC patients with HER2 exon 20 insertions, and reduce the incidence of pyrotinib-related diarrhea. We believe thalidomide is the stone that can hit two birds. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04382300 . Registered on May 11, 2020.

Acute pharmacological degradation of Helios destabilizes regulatory T cells.

The zinc-finger transcription factor Helios is critical for maintaining the identity, anergic phenotype and suppressive activity of regulatory T (Treg) cells. While it is an attractive target to enhance the efficacy of currently approved immunotherapies, no existing approaches can directly modulate Helios activity or abundance. Here, we report the structure-guided development of small molecules that recruit the E3 ubiquitin ligase substrate receptor cereblon to Helios, thereby promoting its degradation. Pharmacological Helios degradation destabilized the anergic phenotype and reduced the suppressive activity of Treg cells, establishing a route towards Helios-targeting therapeutics. More generally, this study provides a framework for the development of small-molecule degraders for previously unligandable targets by reprogramming E3 ligase substrate specificity.

The paradoxical pharmacological mechanisms of lenalidomide and bortezomib in the treatment of multiple myeloma.

The combination of bortezomib (Velcade, PS-341) and lenalidomide (Revlimid) for the treatment of multiple myeloma was proved by USA Food and Drug Administration in 2006. Lenalidomide prevents the proliferation of multiple myeloma cells through binding to cereblon and promoting the ubiquitinational degradation of IKZF1 (Ikaros)/IKZF3 (Aiolos). However, the proteasome inhibitor bortezomib would inhibit the ubiquitinational degradation of IKZF1/IKZF3. How bortezomib could not block the antiproliferative effect of lenalidomide on multiple myeloma cells, which is the paradoxical pharmacological mechanisms in multiple myeloma. In this review, we summarized recent advances in molecular mechanisms underlying the combination of bortezomib and lenalidomide for the treatment multiple myeloma, discussed the paradoxical pharmacological mechanisms of lenalidomide and bortezomib in the treatment of multiple myeloma.

Humanized cereblon mice revealed two distinct therapeutic pathways of immunomodulatory drugs.

Immunomodulatory drugs (IMiDs), including thalidomide derivatives such as lenalidomide and pomalidomide, offer therapeutic benefit in several hematopoietic malignancies and autoimmune/inflammatory diseases. However, it is difficult to study the IMiD mechanism of action in murine disease models because murine cereblon (CRBN), the substrate receptor for IMiD action, is resistant to some of IMiDs therapeutic effects. To overcome this difficulty, we generated humanized cereblon (CRBNI391V) mice thereby providing an animal model to unravel complex mechanisms of action in a murine physiological setup. In our current study, we investigated the degradative effect toward IKZF1 and CK-1α, a target substrate of IMiDs. Unlike WT mice which were resistant to lenalidomide and pomalidomide, T lymphocytes from CRBNI391V mice responded with a higher degree of IKZF1 and CK-1α protein degradation. Furthermore, IMiDs resulted in an increase in IL-2 among CRBNI391V mice but not in the WT group. We have also tested a thalidomide derivative, FPFT-2216, which showed an inhibitory effect toward IKZF1 protein level. As opposed to pomalidomide, FPFT-2216 and lenalidomide degrades CK-1α. Additionally, we assessed the potential therapeutic effects of IMiDs in dextran sodium sulfate (DSS)-induced colitis. In both WT and humanized mice, lenalidomide showed a significant therapeutic effect in the DSS model of colitis, while the effect of pomalidomide was less pronounced. Thus, while IMiDs' degradative effect on IKZF1 and CK-1α, and up-regulation of IL-2, is dependent on CRBN, the therapeutic benefit of IMiDs in a mouse model of inflammatory bowel disease occurs through a CRBN-IMiD binding region independent pathway.

Cereblon modulator iberdomide induces degradation of the transcription factors Ikaros and Aiolos: immunomodulation in healthy volunteers and relevance to systemic lupus erythematosus.

OBJECTIVES: IKZF1 and IKZF3 (encoding transcription factors Ikaros and Aiolos) are susceptibility loci for systemic lupus erythematosus (SLE). The pharmacology of iberdomide (CC-220), a cereblon (CRBN) modulator targeting Ikaros and Aiolos, was studied in SLE patient cells and in a phase 1 healthy volunteer study. METHODS: CRBN, IKZF1 and IKZF3 gene expression was measured in peripheral blood mononuclear cells (PBMC) from patients with SLE and healthy volunteers. Ikaros and Aiolos protein levels were measured by Western blot and flow cytometry. Anti-dsDNA and anti-phospholipid autoantibodies were measured in SLE PBMC cultures treated for 7 days with iberdomide. Fifty-six healthy volunteers were randomised to a single dose of iberdomide (0.03-6 mg, n=6 across seven cohorts) or placebo (n=2/cohort). CD19+ B cells, CD3+ T cells and intracellular Aiolos were measured by flow cytometry. Interleukin (IL)-2 and IL-1ß production was stimulated with anti-CD3 and lipopolysaccharide, respectively, in an ex vivo whole blood assay. RESULTS: SLE patient PBMCs expressed significantly higher CRBN (1.5-fold), IKZF1 (2.1-fold) and IKZF3 (4.1-fold) mRNA levels compared with healthy volunteers. Iberdomide significantly reduced Ikaros and Aiolos protein levels in B cells, T cells and monocytes. In SLE PBMC cultures, iberdomide inhibited anti-dsDNA and anti-phospholipid autoantibody production (IC50 ≈10 nM). Single doses of iberdomide (0.3-6 mg) in healthy volunteers decreased intracellular Aiolos (minimum mean per cent of baseline: ≈12%-28% (B cells); ≈0%-33% (T cells)), decreased absolute CD19+ B cells, increased IL-2 and decreased IL-1ß production ex vivo. CONCLUSIONS: These findings demonstrate pharmacodynamic activity of iberdomide and support its further clinical development for the treatment of SLE. TRIAL REGISTRATION NUMBER: NCT01733875; Results.

A calcium- and calpain-dependent pathway determines the response to lenalidomide in myelodysplastic syndromes.

Despite the high response rates of individuals with myelodysplastic syndrome (MDS) with deletion of chromosome 5q (del(5q)) to treatment with lenalidomide (LEN) and the recent identification of cereblon (CRBN) as the molecular target of LEN, the cellular mechanism by which LEN eliminates MDS clones remains elusive. Here we performed an RNA interference screen to delineate gene regulatory networks that mediate LEN responsiveness in an MDS cell line, MDSL. We identified GPR68, which encodes a G-protein-coupled receptor that has been implicated in calcium metabolism, as the top candidate gene for modulating sensitivity to LEN. LEN induced GPR68 expression via IKAROS family zinc finger 1 (IKZF1), resulting in increased cytosolic calcium levels and activation of a calcium-dependent calpain, CAPN1, which were requisite steps for induction of apoptosis in MDS cells and in acute myeloid leukemia (AML) cells. In contrast, deletion of GPR68 or inhibition of calcium and calpain activation suppressed LEN-induced cytotoxicity. Moreover, expression of calpastatin (CAST), an endogenous CAPN1 inhibitor that is encoded by a gene (CAST) deleted in del(5q) MDS, correlated with LEN responsiveness in patients with del(5q) MDS. Depletion of CAST restored responsiveness of LEN-resistant non-del(5q) MDS cells and AML cells, providing an explanation for the superior responses of patients with del(5q) MDS to LEN treatment. Our study describes a cellular mechanism by which LEN, acting through CRBN and IKZF1, has cytotoxic effects in MDS and AML that depend on a calcium- and calpain-dependent pathway.

Pomalidomide reverses γ-globin silencing through the transcriptional reprogramming of adult hematopoietic progenitors.

Current therapeutic strategies for sickle cell anemia are aimed at reactivating fetal hemoglobin. Pomalidomide, a third-generation immunomodulatory drug, was proposed to induce fetal hemoglobin production by an unknown mechanism. Here, we report that pomalidomide induced a fetal-like erythroid differentiation program, leading to a reversion of γ-globin silencing in adult human erythroblasts. Pomalidomide acted early by transiently delaying erythropoiesis at the burst-forming unit-erythroid/colony-forming unit-erythroid transition, but without affecting terminal differentiation. Further, the transcription networks involved in γ-globin repression were selectively and differentially affected by pomalidomide including BCL11A, SOX6, IKZF1, KLF1, and LSD1. IKAROS (IKZF1), a known target of pomalidomide, was degraded by the proteasome, but was not the key effector of this program, because genetic ablation of IKZF1 did not phenocopy pomalidomide treatment. Notably, the pomalidomide-induced reprogramming was conserved in hematopoietic progenitors from individuals with sickle cell anemia. Moreover, multiple myeloma patients treated with pomalidomide demonstrated increased in vivo γ-globin levels in their erythrocytes. Together, these data reveal the molecular mechanisms by which pomalidomide reactivates fetal hemoglobin, reinforcing its potential as a treatment for patients with ß-hemoglobinopathies.

Combined exposure to X-irradiation followed by N-ethyl-N-nitrosourea treatment alters the frequency and spectrum of Ikaros point mutations in murine T-cell lymphoma.

Ionizing radiation is a well-known carcinogen, but its potency may be influenced by other environmental carcinogens, which is of practical importance in the assessment of risk. Data are scarce, however, on the combined effect of radiation with other environmental carcinogens and the underlying mechanisms involved. We studied the mode and mechanism of the carcinogenic effect of radiation in combination with N-ethyl-N-nitrosourea (ENU) using doses approximately equal to the corresponding thresholds. B6C3F1 mice exposed to fractionated X-irradiation (Kaplan's method) followed by ENU developed T-cell lymphomas in a dose-dependent manner. Radiation doses above an apparent threshold acted synergistically with ENU to promote lymphoma development, whereas radiation doses below that threshold antagonized lymphoma development. Ikaros, which regulates the commitment and differentiation of lymphoid lineage cells, is a critical tumor suppressor gene frequently altered in both human and mouse lymphomas and shows distinct mutation spectra between X-ray- and ENU-induced lymphomas. In the synergistically induced lymphomas, we observed a low frequency of LOH and an inordinate increase of Ikaros base substitutions characteristic of ENU-induced point mutations, G:C to A:T at non-CpG, A:T to G:C, G:C to T:A and A:T to T:A. This suggests that radiation doses above an apparent threshold activate the ENU mutagenic pathway. This is the first report on the carcinogenic mechanism elicited by combined exposure to carcinogens below and above threshold doses based on the mutation spectrum of the causative gene. These findings constitute a basis for assessing human cancer risk following exposure to multiple carcinogens.