New Insights on the Emerging Genomic Landscape of CXCR4 in Cancer: A Lesson from WHIM

Investigational CXCR4 inhibitors in early phase development for the treatment of hematological malignancies

INTRODUCTION

CXCR4/CXCL12 axis regulates cell proliferation, survival, and differentiation, as well as the homing and mobilization of hematopoietic stem cells (HSCs) from bone marrow niches to the peripheral blood. Furthermore, CXCR4 and CXCL12 are key mediators of cross-talk between hematological malignancies and their microenvironments. CXCR4 overexpression drives disease progression, boosts tumor cell survival, and promotes chemoresistance, leading to poor prognosis.

AREAS COVERED

In light of these discoveries, scientific investigations, and clinical trials have underscored the therapeutic promise found in small-molecule antagonists like plerixafor, peptides/peptidomimetics, such as BKT140, monoclonal antibodies like PF-06747143 and ulocuplumab, as well as microRNAs. Their efficacy is evident in reducing tumor burden, inducing apoptosis and sensitizing malignant cells to conventional chemotherapies. This overview delves into the pathogenic role of the CXC4/CXCL12 axis in hematological neoplasms and examines the clinical application of key CXCR4 antagonists.

EXPERT OPINION

The information collectively emphasizes the potential of CXCR4 antagonists as a therapeutic strategy for hematologic malignancies, showcasing advancements in preclinical and clinical studies. As these therapeutic strategies progress through clinical trials, their potential to reshape the prognosis of hematologic malignancies will become increasingly apparent.

Discovery of differentially expressed proteins for CAR-T therapy of ovarian cancers with a bioinformatics analysis

Target antigens are crucial for developing chimeric antigen receptor (CAR)-T cells, but their application to ovarian cancers is limited. This study aimed to identify potential genes as CAR-T-cell antigen candidates for ovarian cancers. A differential gene expression analysis was performed on ovarian cancer samples from four datasets obtained from the GEO datasets. Functional annotation, pathway analysis, protein localization, and gene expression analysis were conducted using various datasets and tools. An oncogenicity analysis and network analysis were also performed. In total, 153 differentially expressed genes were identified in ovarian cancer samples, with 60 differentially expressed genes expressing plasma membrane proteins suitable for CAR-T-cell antigens. Among them, 21 plasma membrane proteins were predicted to be oncogenes in ovarian cancers, with nine proteins playing crucial roles in the network. Key genes identified in the oncogenic pathways of ovarian cancers included MUC1, CXCR4, EPCAM, RACGAP1, UBE2C, PRAME, SORT1, JUP, and CLDN3, suggesting them as recommended antigens for CAR-T-cell therapy for ovarian cancers. This study sheds light on potential targets for immunotherapy in ovarian cancers.

Characterization of a new WHIM syndrome mutant reveals mechanistic differences in regulation of the chemokine receptor CXCR4

WHIM syndrome is a rare immunodeficiency disorder that is characterized by warts, hypogammaglobulinemia, infections, and myelokathexis. While several gain-of-function mutations that lead to C-terminal truncations, frame shifts and point mutations in the chemokine receptor CXCR4 have been identified in WHIM syndrome patients, the functional effect of these mutations are not fully understood. Here, we report on a new WHIM syndrome mutation that results in a frame shift within the codon for Ser339 (S339fs5) and compare the properties of S339fs5 with wild-type CXCR4 and a previously identified WHIM syndrome mutant, R334X. The S339fs5 and R334X mutants exhibited significantly increased signaling compared to wild-type CXCR4 including agonist-promoted calcium flux and extracellular-signal-regulated kinase activation. This increase is at least partially due to a significant decrease in agonist-promoted phosphorylation, β-arrestin binding, and endocytosis of S339fs5 and R334X compared with wild-type CXCR4. Interestingly, there were also significant differences in receptor degradation, with S339fs5 having a very high basal level of degradation compared with that of R334X and wild-type CXCR4. In contrast to wild-type CXCR4, both R334X and S339fs5 were largely insensitive to CXCL12-promoted degradation. Moreover, while basal and agonist-promoted degradation of wild-type CXCR4 was effectively inhibited by the CXCR4 antagonist TE-14016, this had no effect on the degradation of the WHIM mutants. Taken together, these studies identify a new WHIM syndrome mutant, CXCR4-S339fs5, which promotes enhanced signaling, reduced phosphorylation, β-arrestin binding and endocytosis, and a very high basal rate of degradation that is not protected by antagonist treatment.

Initial Experience Treating HPV-Related Laryngeal Diseases with Oral Brincidofovir: A Pilot Study

OBJECTIVE

To determine if brincidofovir, an oral analog of cidofovir that achieves high tissue levels of the active metabolite with low systemic toxicity, has an observable effect on HPV-related disease of the larynx.

METHODS

Two patients with laryngeal recurrent respiratory papillomatosis (one each of genotypes 6 and 11) and 1 with recurring aryepiglottic fold carcinoma in situ (genotype 16) received oral brincidofovir according to protocol. Close-range videoendoscopic examinations were done during and after the study period to observe disease behavior in the absence of other interventions, and after subsequent surgical intervention. Disease character and magnitude of recurrence for each patient were compared to their patterns prior to brincidofovir.

RESULTS

Brincidofovir reduced papilloma burden in 1 patient and markedly attenuated the rate and magnitude of recurrence in both. After surgical intervention, Patient 1 remains disease-free at 10 years (7 years from last intervention) and Patient 2 has no symptoms at 8 years. Patient 3 with recurring carcinoma in situ has required less frequent resections and specimens show reduced degrees of dysplasia present only in islands amid normal mucosa at 8 years (currently no evidence of disease at 21 months from last intervention).

CONCLUSION

Brincidofovir appears to attenuate HPV disease of the larynx in this small pilot study, though further investigation is required because of the highly variable nature of the disease and potential confounding factors.

Aberrant CXCR4 Signaling at Crossroad of WHIM Syndrome and Waldenstrom's Macroglobulinemia

Given its pleiotropic functions, including its prominent role in inflammation, immune responses and cancer, the C-X-C chemokine receptor type 4 (CXCR4) has gained significant attention in recent years and has become a relevant target in drug development. Although the signaling properties of CXCR4 have been extensively studied, several aspects deserve deeper investigations. Mutations in the C-term tail of the CXCR4 gene cause WHIM syndrome, a rare congenital immunodeficiency associated by chronic leukopenia. Similar mutations have also been recently identified in 30% of patients affected by Waldenstrom’s macroglobulinaemia, a B-cell neoplasia with bone marrow accumulation of malignant cells. An ample body of work has been generated to define the impact of WHIM mutations on CXCR4 signaling properties and evaluate their role on pathogenesis, diagnosis, and response to therapy, although the identity of disease-causing signaling pathways and their relevance for disease development in different genetic variants are still open questions. This review discusses the current knowledge on biochemical properties of CXCR4 mutations to identify their prototypic signaling profile potentially useful to highlighting novel opportunities for therapeutic intervention.

New CXCR4 Antagonist Peptide R (Pep R) Improves Standard Therapy in Colorectal Cancer

The chemokine receptor CXCR4 is overexpressed and functional in colorectal cancer. To investigate the role of CXCR4 antagonism in potentiating colon cancer standard therapy, the new peptide CXCR4 antagonist Peptide R (Pep R) was employed. Human colon cancer HCT116 xenograft-bearing mice were treated with chemotherapeutic agents (CT) 5-Fluorouracil (5FU) and oxaliplatin (OX) or 5FU and radio chemotherapy (RT-CT) in the presence of Pep R. After two weeks, CT plus Pep R reduced by 4-fold the relative tumor volume (RTV) as compared to 2- and 1.6-fold reductions induced, respectively, by CT and Pep R. In vitro Pep R addition to CT/RT-CT impaired HCT116 cell growth and further reduced HCT116 and HT29 clonal capability. Thus, the hypothesis that Pep R could target the epithelial mesenchyme transition (EMT) process was evaluated. While CT decreased ECAD and increased ZEB-1 and CD90 expression, the addition of Pep R restored the pretreatment expression. In HCT116 and HT29 cells, CT/RT-CT induced a population of CD133+CXCR4+ cells, supposedly a stem-resistant cancer cell population, while Pep R reduced it. Taken together, the results showed that targeting CXCR4 ameliorates the effect of treatment in colon cancer through inhibition of cell growth and reversal of EMT treatment-induced markers, supporting further clinical studies.