[The characteristics and impact on prognosis of cytopenia after anti-BCMA-CAR-T therapy in patients with relapsed and refractory multiple myeloma]

Objective: To investigate the characteristics of cytopenia and its impact on prognosis in patients with relapsed and refractory multiple myeloma (RRMM) after B-cell maturation antigen (BCMA) chimeric antigen receptor T-cell (CAR-T) immunotherapy therapy. Methods: Clinical data of 36 RRMM patients received BCMA CAR-T therapy at the First Affiliated Hospital of Nanjing Medical University from April 2017 to March 2023 were retrospectively collected. Among them, there were 17 males and 19 females, with an age [M (Q1, Q3)] of 62 (53, 67) years. The follow-up deadline was August 31, 2023, and the follow-up time [M (Q1, Q3)] was 33 (10, 30) months. The characteristics of cytopenia at different time points before lymphodepleting chemotherapy and after CAR-T cell infusion in all patients were analyzed. Kaplan-Meier method was used to compare the differences in progression-free survival (PFS) and overall survival (OS) in patients with different clinical characteristics. Single-cell sequencing analysis was used to analyze the changes in hematopoietic stem cells in three patients after CAR-T cell therapy. Results: The incidence of cytopenia after BCMA CAR-T cell therapy in 36 RRMM patients reached 100%. The incidence of neutropenia peaked on the 7th and 28th day after cell infusion with a biphasic pattern of change.Patients with all grade neutropenia reached 61.1% (22/36) and grade 3 or higher reached 33.3% (12/36) on the 7th day, while patients with all grade neutropenia reached 67.9% (19/28) and grade 3 or higher reached 28.6% (8/28) on the 28th day (P<0.001),respectively. The occurrence rate of lymphopenia reached a peak on the day of CAR-T cell infusion [97.2% (35/36) patients showed lymphopenia, while 80.6% (29/36) patients showed grade 3 or higher lymphopenia] (P<0.001).The incidence of all grade of thrombocytopenia and severe thrombocytopenia (grade 3 or higher) peaked on the 14th day after cell infusion, with the rates of 69.4% (25/36) and 30.6% (11/36) respectively, which had a prolonged duration(P<0.001). Even after 12 months, 40% (8/20) of patients still experienced thrombocytopenia.The incidence of anemia peaked on the 7th and 14th day after cell infusion, with a rate of 100% (36/36) (P<0.001). 50% (10/20) of patients still had anemia even 12 months after cell infusion. Kaplan-Meier survival analysis showed that patients with thrombocytopenia < grade 3 had undefined OS, while patients with thrombocytopenia ≥grade 3 had shorter OS [17 (95%CI: 2-32) months, χ2=4.154, P=0.042], indicating a poorer prognosis. However, there was no statistically significant difference in the relationship between other cytopenia and survival (all P>0.05). Single-cell sequencing analysis of bone marrow cells revealed decreased proliferation, increased apoptosis, and cell cycle arrest of hematopoietic stem cells after CAR-T cell infusion. Conclusions: All patients experienced varying degrees of cytopenia after receiving BCMA CAR-T cell infusion, and patients with thrombocytopenia ≥grade 3 had shorter OS and poorer prognosis.

ZDHHC5-mediated S-palmitoylation of FAK promotes its membrane localization and epithelial-mesenchymal transition in glioma

BACKGROUND

Abnormal activation of FAK is associated with tumor development and metastasis. Through interactions with other intracellular signalling molecules, FAK influences cytoskeletal remodelling, modulation of adhesion signalling, and activation of transcription factors, promoting migration and invasion of tumor cells. However, the exact mechanism that regulates these processes remains unresolved. Herein, our findings indicate that the S-palmitoylation of FAK is crucial for both its membrane localization and activation.

METHODS

The palmitoylation of FAK in U251 and T98G cells was assessed by an acyl-PEG exchange (APE) assay and a metabolic incorporation assay. Cellular palmitoylation was inhibited using 2-bromopalmitate, and the palmitoylation status and cellular localization of FAK were determined. A metabolic incorporation assay was used to identify the potential palmitoyl acyltransferase and the palmitoylation site of FAK. Cell Counting Kit-8 (CCK8) assays, colony formation assays, and Transwell assays were conducted to assess the impact of ZDHHC5 in GBM. Additionally, intracranial GBM xenografts were utilized to investigate the effects of genetically silencing ZDHHC5 on tumor growth.

RESULTS

Inhibiting FAK palmitoylation leads to its redistribution from the membrane to the cytoplasm and a decrease in its phosphorylation. Moreover, ZDHHC5, a protein-acyl-transferase (PAT), catalyzes this key modification of FAK at C456. Knockdown of ZDHHC5 abrogates the S-palmitoylation and membrane distribution of FAK and impairs cell proliferation, invasion, and epithelial-mesenchymal transition (EMT). Taken together, our research reveals the crucial role of ZDHHC5 as a PAT responsible for FAK S-palmitoylation, membrane localization, and activation.

CONCLUSIONS

These results imply that targeting the ZDHHC5/FAK axis has the potential to be a promising strategy for therapeutic interventions for glioblastoma (GBM). Video Abstract.