Proteus syndrome with progressive paralysis of the unilateral lower limb: A rare case report and literature review.

Objective: Proteus syndrome, a rare disorder with an incidence of one in a million, is characterized by connective tissue nevi, asymmetric limb overgrowth, and abnormal subcutaneous adipose tissue distribution. Limited awareness of this condition often hinders accurate clinical diagnosis. We report a case of Proteus syndrome with concurrent progressive paralysis in the unilateral lower limb, aiming to enhance understanding of the disease and its associated complications. Methods: The patient, an 11-year-old male, has been conclusively diagnosed with Proteus Syndrome. This diagnosis was established by analyzing clinical manifestations, imaging studies, and laboratory tests. In addition, a literature review was conducted to systematically elucidate the etiology, diagnosis, treatment, and prognosis of this condition. Results: According to the clinical manifestations, we confirmed a case of Proteus syndrome. This example exhibits the general characteristics of patients with severe hemihypertrophy of the bilateral lower limbs, anomalies in hypodermic and adipose distribution, and unilateral lower limb progressive paralysis. Pathological biopsy confirmed the right chest wall mass as a lipoma. Notably, the patient experiences lower limb movement disorders caused by intraspinal disease. At the same time, the gene sequencing results of this Proteus syndrome patient showed mutations in the IDUS gene and SPECC1L gene, which have not been reported before. Conclusion: We diagnosed Proteus Syndrome with lower limb sensorimotor abnormalities, which may be caused by mutations in the IDUS gene or SPECC1L gene. This is the first report of these kinds of gene mutations in association with Proteus Syndrome.

Advances in second hematopoietic stem cell transplantation.

Hematopoietic stem cell transplantation (HSCT) is a widely used treatment for malignant hematological diseases; however, some patients inevitably experience relapse. Therefore, for patients who relapse after the first HSCT (HSCT1), a standard treatment regimen must be developed. A second hematopoietic stem cell transplantation (HSCT2) is a possible treatment option. Several studies have analyzed the feasibility of HSCT2. Previous studies have shown that various factors may affect the efficacy of HSCT2, including the hematopoietic cell transplantation comorbidity index, duration of remission after HSCT1, occurrence of chronic graft-versus-host disease, and disease status before HSCT2. However, the selection of donors for HSCT2 does not affect the transplantation efficacy. HSCT2 also presents a risk of relapse, and the prognosis of patients after relapse is poor. Further research on the treatment of patients after relapse is warranted.

Single-cell analysis of the survival mechanisms of fratricidal CAR-T targeting of T cell malignancies.

Chimeric antigen receptor T (CAR-T) cell therapy targeting T cell tumors still faces many challenges, one of which is its fratricide due to the target gene expressed on CAR-T cells. Despite this, these CAR-T cells can be expanded in vitro by extending the culture time and effectively eliminating malignant T cells. However, the mechanisms underlying CAR-T cell survival in cell subpopulations, the molecules involved, and their regulation are still unknown. We performed single-cell transcriptome profiling to investigate the fratricidal CAR-T products (CD26 CAR-Ts and CD44v6 CAR-Ts) targeting T cells, taking CD19 CAR-Ts targeting B cells from the same donor as a control. Compared with CD19 CAR-Ts, fratricidal CAR-T cells exhibit no unique cell subpopulation, but have more exhausted T cells, fewer cytotoxic T cells, and more T cell receptor (TCR) clonal amplification. Furthermore, we observed that fratricidal CAR-T cell survival was accompanied by target gene expression. Gene expression results suggest that fratricidal CAR-T cells may downregulate their human leukocyte antigen (HLA) molecules to evade T cell recognition. Single-cell regulatory network analysis and suppression experiments revealed that exhaustion mediated by critical regulatory factors may contribute to fratricidal CAR-T cell survival. Together, these data provide valuable and first-time insights into the survival of fratricidal CAR-T cells.

CAR-T cell combination therapies in hematologic malignancies.

Chimeric antigen receptor-T cell therapy, a groundbreaking cancer treatment, has achieved remarkable success against hematologic malignancies. However, CAR-T monotherapy faces challenges in certain cases, including treatment tolerance and relapse rates. To overcome these challenges, researchers are investigating combining CAR-T cells with other treatments to enhance therapeutic efficacy. Therefore, this review aims to investigate the progress of research in combining CAR-T cells for hematologic malignancies. It covers the basic principles and clinical applications of CAR-T cell therapy, detailing combinations with chemotherapy, immune checkpoint inhibitors, targeted drugs, radiotherapy, hematopoietic stem cell transplantation, and other treatments. These combinations synergistically enhance the antitumor effects of CAR-T cells and comprehensively target tumors through different mechanisms, improving patient response and survival rates.

Advances in CAR-T-cell therapy in T-cell malignancies.

Significant advances have been made in chimeric antigen receptor T (CAR-T)-cell therapy for the treatment of recurrent or refractory B-cell hematologic malignancies. However, CAR-T-cell therapy has not yet achieved comparable success in the management of aggressive T-cell malignancies. This article reviews the challenges of CAR-T-cell therapy in treating T-cell malignancies and summarizes the progress of preclinical and clinical studies in this area. We present an analysis of clinical trials of CAR-T-cell therapies for the treatment of T-cell malignancies grouped by target antigen classification. Moreover, this review focuses on the major challenges encountered by CAR-T-cell therapies, including the nonspecific killing due to T-cell target antigen sharing and contamination with cell products during preparation. This review discusses strategies to overcome these challenges, presenting novel therapeutic approaches that could enhance the efficacy and applicability of CAR-T-cell therapy in the treatment of T-cell malignancies. These ideas and strategies provide important information for future studies to promote the further development and application of CAR-T-cell therapy in this field.

Advances in research on factors affecting chimeric antigen receptor T-cell efficacy.

Chimeric antigen receptor T-cell (CAR-T) therapy is becoming an effective technique for the treatment of patients with relapsed/refractory hematologic malignancies. After analyzing patients with tumor progression and sustained remission after CAR-T cell therapy, many factors were found to be associated with the efficacy of CAR-T therapy. This paper reviews the factors affecting the effect of CAR-T such as tumor characteristics, tumor microenvironment and immune function of patients, CAR-T cell structure, construction method and in vivo expansion values, lymphodepletion chemotherapy, and previous treatment, and provides a preliminary outlook on the corresponding therapeutic strategies.

Updates of primary central nervous system lymphoma.

Lymphoma occurring in the central nervous system is considered primary central nervous system lymphoma (PCNSL), usually without systematic lesions. Over the last few decades, a deep understanding of PCNSL has been lacking due to the low incidence rate, and the overall survival and progression-free survival of patients with PCNSL are lower than those with other types of non-Hodgkin lymphoma. Recently, there have been several advancements in research on PCNSL. Advances in diagnosis of the disease are primarily reflected in the promising diagnostic efficiency of novel biomarkers. Pathogenesis mainly involves abnormal activation of nuclear factor kappa-B signaling pathways, copy number variations, and DNA methylation. Novel therapies such as Bruton's tyrosine kinase inhibitors, immunomodulatory drugs, immune checkpoint inhibitors, and phosphoinositide 3-kinase/mammalian target of rapamycin inhibitors are being evaluated as possible treatment options for PCNSL, especially for relapsed/refractory (R/R) cases. Several clinical trials also indicated the promising feasibility and efficacy of chimeric antigen receptor T-cell therapy for selected R/R PCNSL patients. This review focuses on discussing recent updates, including the diagnosis, pathogenesis, and novel therapy of PCNSL.

Adverse Reactions in Relapsed/Refractory B-Cell Lymphoma Administered with Chimeric Antigen Receptor T Cell Alone or in Combination with Autologous Stem Cell Transplantation.

(1) Background: The combination of CAR-T with ASCT has been observed to enhance the efficacy of CAR-T cell therapy. However, the impact of this combination on adverse reactions is still uncertain. (2) Methods: Between January 2019 and February 2023, 292 patients diagnosed with r/r B-cell lymphoma received either CAR-T therapy alone or in combination with ASCT at our institution. We evaluated the incidence of CRS and CRES and utilized a logistic regression model to identify factors contributing to severe CRS (grade 3-4) and CRES (grade 3-4). (3) Results: The overall incidence of CRS and CRES was 78.9% and 8.2% in 147 patients receiving CAR-T alone, and 95.9% and 15.2% in 145 patients receiving CAR-T combined with ASCT, respectively. The incidence of overall CRS (p < 0.0001) and mild CRS (grade 1-2) (p = 0.021) was elevated in the ASCT combined with CAR-T group. No significant difference was observed in severe CRS and CRES between the groups. Among the 26 cases of lymphoma involving the central nervous system (CNS), 96.2% (25/26) developed CRS (15.4% grade 3-4), and 34.6% (9/26) manifested CRES (7.7% grade 3-4). Female patients had a lower incidence of severe CRS but a higher incidence of severe CRES. Lymphomas with CNS involvement demonstrated a higher risk of CRES compared to those without central involvement. (4) Conclusions: The combination of ASCT with CAR-T demonstrated a preferable option in r/r B-cell lymphoma without an increased incidence of severe CRS and CRES.

Neurological involvement in hematopoietic stem cell transplantation-associated thrombotic microangiopathy.

Transplantation-associated thrombotic microangiopathy (TA-TMA) is a well-recognized serious complication of hematopoietic stem cell transplantation (HSCT). The understanding of TA-TMA pathophysiology has expanded in recent years. Dysregulation of the complement system is thought to cause endothelial injury and, consequently, microvascular thrombosis and tissue damage. TA-TMA can affect multiple organs, and each organ exhibits specific features of injury. Central nervous system (CNS) manifestations of TA-TMA include posterior reversible encephalopathy syndrome, seizures, and encephalopathy. The development of neurological dysfunction is associated with a significantly lower overall survival in patients with TA-TMA. However, there are currently no established histopathological or radiological criteria for the diagnosis of CNS TMA. Patients who receive total body irradiation (TBI), calcineurin inhibitors (CNI), and severe acute and chronic graft-versus-host disease (GVHD) are at a high risk of experiencing neurological complications related to TA-TMA and should be considered for directed TA-TMA therapy. However, the incidence and clinical manifestations of TA-TMA neurotoxicity remain unclear. Studies specifically examining the involvement of CNS in TMA syndromes are limited. In this review, we discuss clinical manifestations and imaging abnormalities in patients with nervous system involvement in TA-TMA. We summarize the mechanisms underlying TA-TMA and its neurological complications, including endothelial injury, evidence of complement activation, and treatment options for TA-TMA.

Efficacy of programmed cell death 1 inhibitor maintenance after chimeric antigen receptor T cells in patients with relapsed/refractory B-cell non-Hodgkin-lymphoma.

INTRODUCTION: Chimeric antigen receptor (CAR)-T cells obtained long-term durability in about 30% to 40% of relapsed/refractory (r/r) B-cell non-Hodgkin lymphoma (B-NHL). Maintenance therapy after CAR-T is necessary, and PD1 inhibitor is one of the important maintenance therapy options. METHODS: A total of 173 r/r B-NHL patients treated with PD1 inhibitor maintenance following CD19/22 CAR-T therapy alone or combined with autologous hematopoietic stem cell transplantation (ASCT) from March 2019 to July 2022 were assessed for eligibility for two trials. There were 81 patients on PD1 inhibitor maintenance therapy. RESULTS: In the CD19/22 CAR-T therapy trial, the PD1 inhibitor maintenance group indicated superior objective response rate (ORR) (82.9% vs 60%; P = 0.04) and 2-year progression-free survival (PFS) (59.8% vs 21.3%; P = 0.001) than the non-maintenance group. The estimated 2-year overall survival (OS) was comparable in the two groups (60.1% vs 45.1%; P = 0.112). No difference was observed in the peak expansion levels of CD19 CAR-T and CD22 CAR-T between the two groups. The persistence time of CD19 and CD22 CAR-T in the PD1 inhibitor maintenance group was longer than that in the non-maintenance group. In the CD19/22 CAR-T therapy combined with ASCT trial, no significant differences in ORR (81.4% vs 84.8%; P = 0.67), 2-year PFS (72.3% vs 74.9%; P = 0.73), and 2-year OS (84.1% vs 80.7%; P = 0.79) were observed between non-maintenance and PD1 inhibitor maintenance therapy groups. The peak expansion levels and duration of CD19 and CD22 CAR-T were not statistically different between the two groups. During maintenance treatment with PD1 inhibitor, all adverse events were manageable. In the multivariable analyses, type and R3m were independent predictive factors influencing the OS of r/r B-NHL with PD1 inhibitor maintenance after CAR-T therapy. CONCLUSION: PD1 inhibitor maintenance following CD19/22 CAR-T therapy obtained superior response and survival in r/r B-NHL, but not in the trial of CD19/22 CAR-T cell therapy combined with ASCT.

Recombinant Human Thrombopoietin Promotes Platelet Engraftment in Severe Aplastic Anemia Patients Following Treatment With Haploid Hematopoietic Stem Cell Transplantation using Modified Post-Transplantation Cyclophosphamide.

BACKGROUND: Recombinant human TPO (rhTPO) promotes platelet engraftment in patients after allogeneic HSCT (allo-HSCT). However, the effects of rhTPO on platelet recovery after Haplo-HSCT in patients with severe aplastic anemia (SAA) have not been intensively studied. OBJECTIVE: We aimed to evaluate the efficacy of rhTPO on platelet engraftment in patients with SAA who were treated with Haplo-HSCT using post-transplantation cyclophosphamide (PTCy). STUDY DESIGN: SAA patients who received Haplo-HSCT plus PTCy regimen were divided into the rhTPO group (with subcutaneous injection of rhTPO, n = 28) and Control group (no rhTPO administration, n = 27). The engraftment of platelet/neutrophil, platelet infusion amount, and transplant-related complications between the 2 groups were compared. RESULTS: All 55 patients showed successful hematopoietic reconstitution. The median time of platelet engraftment was 11 (9 to 29) days in the rhTPO group and 14 (9 to 28) days in the Control group (P = .003). The rhTPO group had a significantly reduced amount of infused platelets compared to the Control group (2 (1 to 11.5) versus 3 (1 to 14) therapeutic doses; P = .004). There was no significant difference between the 2 groups regarding median time of neutrophil engraftment, incidence of acute graft-versus-host disease (aGVHD) and chronic GVHD (cGVHD), incidence of cytomegalovirus or Epstein-Barr virus reactivation, 3-yr overall survival rate, and failure-free-survival rate. No obvious adverse reactions were observed in the rhTPO group. CONCLUSION: rhTPO promoted platelet engraftment, reduced the amount of transfused platelets, and demonstrated good safety profiles without evidence of adverse reactions in patients with SAA who received Haplo-HSCT using PTCy regimen.

Case report: Acute HHV6B encephalitis/myelitis post CAR-T cell therapy in patients with relapsed/refractory aggressive B-cell lymphoma.

Background: The development of chimeric antigen receptor (CAR)-T cell therapy has revolutionized treatment outcomes in patients with lymphoid malignancies. However, several studies have reported a relatively high rate of infection in adult patients following CD19-targeting CAR T-cell therapy, particularly in the first 28 days. Notably, acute human herpesvirus 6 B (HHV6B) reactivation occurs in up to two-thirds of allogeneic hematopoietic stem cell transplantation patients. Case presentations: Herein, we describe a report of HHV6B encephalitis/myelitis in three patients with relapsed/refractory diffuse large B-cell lymphoma post CAR T-cell therapy. All three patients received multiple lines of prior treatment (range: 2-9 lines). All patients presented with fever that persisted for at least 2 weeks after CAR-T cell infusion (CTI). Both the onset time and duration were similar to those of the cytokine release syndrome (CRS); nevertheless, the CRS grades of the patients were low (grade 1 or 2). Delirium and memory loss after CTI were the earliest notable mental presentations. Neurological manifestations progressed rapidly, with patients experiencing varying degrees of impaired consciousness, seizures, and coma. Back pain, lumbago, lower limb weakness and uroschesis were also observed in Patient 3, indicating myelitis. High HHV6B loads were detected in all Cerebral spinal fluid (CSF) samples using metagenomic next-generation sequencing (mNGS). Only one patient required high-activity antivirals and IgG intravenous pulse treatment finally recovered, whereas the other two patients died from HHV6B encephalitis. Conclusion: Considering its fatal potential, HHV6B encephalitis/myelitis should be urgently diagnosed post CAR-T cell-based therapy. Furthermore, hematologists should differentially diagnose these conditions from CRS or other immunotherapy-related neurotoxicities as early as possible. The results of this study demonstrate the potential of mNGS in the early diagnosis of HHV6B infection, particularly when the organism is difficult to culture.

Case report: The utilization of crizotinib and brentuximab vedotin as a bridge to autologous stem cell transplantation and followed by CD30-directed CAR-T cell therapy in relapsed/refractory ALK+ ALCL.

Background: Anaplastic lymphoma kinase-positive anaplastic large cell lymphoma (ALK+ ALCL) is a rare, mature T-cell non-Hodgkin lymphoma. The prognosis of patients with relapsed or refractory ALCL following first-line chemotherapy is extremely poor. NCCN guidelines recommend intensified chemotherapy with or without ASCT consolidation for r/r ALCL, however, this is not an effective treatment for all ALK+ALCL. Case report: Herein, we report a patient with relapsed/refractory ALK+ ALCL who received crizotinib and brentuximab vedotin as bridging therapy, followed by autologous stem cell transplantation and sequential anti-CD30 CAR T cell therapy. Conclusion: The patient achieved complete remission and long-term disease-free survival of months and continues to be followed up. The combination therapy model in this case may provide guidance for the management of relapsed/refractory ALK+ ALCL, and further prospective trials are needed to confirm its effectiveness.

Prognostic differences between carmustine, etoposide, cytarabine and melphalan (BEAM) and carmustine, etoposide, cytarabine, melphalan and fludarabine (BEAMF) regimens before autologous stem cell transplantation plus chimeric antigen receptor T therapy in patients with refractory/relapsed B-cell non-Hodgkin-lymphoma.

BACKGROUND AIMS: The combination therapy of autologous hematopoietic stem cell transplantation (ASCT) and chimeric antigen receptor T-cell (CART) therapy has been employed to improve outcomes for relapsed or refractory (R/R) B-cell non-Hodgkin-lymphoma (B-NHL). The widely used conditioning regimen before ASCT plus CART therapy reported in the literature was carmustine, etoposide, cytarabine and melphalan (BEAM). However, whether adding fludarabine to the BEAM regimen (BEAMF) can improve the survival of patients with R/R B-NHL remains unknown. METHODS: In total, 39 and 19 patients with R/R B-NHL were enrolled to compare clinical outcomes in the BEAM and BEAMF regimens before ASCT plus CD19/22 CART therapy, respectively. RESULTS: The objective response (OR) rates at 3 months to BEAM and BEAMF regimens before ASCT plus CD19/22 CART therapy were 71.8% and 94.7%, respectively (P = 0.093). The BEAMF regimen showed a trend towards a superior duration of response compared with the BEAM regimen (P = 0.09). After a median follow-up of 28 months (range: 0.93-51.9 months), the BEAMF regimen demonstrated superior 2-year progression-free survival (PFS) (89.5% versus 63.9%; P = 0.048) and 2-year overall survival (OS) (100% vs 77.3%; P = 0.035) compared with the BEAM regimen. In the multivariable Cox regression analysis, OR at month 3 (responders) was remarkably correlated with better OS (hazard ratio: 0.112, P = 0.005) compared with OR (non-responders). CONCLUSIONS: For patients with R/R B-NHL, the BEAMF regimen before ASCT plus CD19/22 CART therapy was correlated with superior PFS and OS than the BEAM regimen, and the BEAMF regimen is a promising alternative conditioning regimen for ASCT plus CAR-T therapy.

The critical role of endothelial cell in the toxicity associated with chimeric antigen receptor T cell therapy and intervention strategies.

Chimeric antigen receptor (CAR)-T cell therapy has shown promising results in patients with hematological malignancies. However, many patients still have poor prognoses or even fatal outcomes due to the life-threatening toxicities associated with the therapy. Moreover, even after improving the known influencing factors (such as number or type of CAR-T infusion) related to CAR-T cell infusion, the results remain unsatisfactory. In recent years, it has been found that endothelial cells (ECs), which are key components of the organization, play a crucial role in various aspects of immune system activation and inflammatory response. The levels of typical markers of endothelial activation positively correlated with the severity of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxic syndrome (ICANS), suggesting that ECs are important targets for intervention and toxicity prevention. This review focuses on the critical role of ECs in CRS and ICANS and the intervention strategies adopted.

Upper gastrointestinal tract immune-related adverse events: Two cases of obstructive complications occurred in immune consolidation therapy after sequential chimeric antigen receptor T cell therapy with autologous hematopoietic stem cell transplantation for refractory/relapsed diffuse large B cell lymphoma.

Key Clinical Message: Immune checkpoint inhibitors are a very popular method of treating malignant tumors. But its side effects cannot be ignored. This study revealed obstructive complications during immune consolidation therapy following sequential chimeric antigen receptor T cell therapy with autologous hematopoietic stem cell transplantation in two patients with diffuse large b cell lymphoma (DLBCL). Both our patients had the same symptoms of vomiting and inability to eat due to pyloric obstruction, it should be highlighted that this is a relatively rare and irreversible complication of upper gastrointestinal caused by immune consolidation therapy. Abstract: Immune checkpoint inhibitors (ICIs) have become the standard therapy for many malignant tumors.However, ICIs are associated with unique immune-related adverse events (irAEs) caused by dysregulated immune activation and associated complications have been observed in patients. Here, we report two cases of patients with pyloric obstruction and duodenal ulcers induced by the use of sintilimab, which provides some guidance for the widely used anti-programmed death-1 therapy. During the entire treatment progression for such patients, the correct differential diagnosis of adverse effects and the use of immunosuppressive agents such as glucocorticoids are essential to facilitate early prevention and intervention of irAEs.

The feedback loop of EFTUD2/c-MYC impedes chemotherapeutic efficacy by enhancing EFTUD2 transcription and stabilizing c-MYC protein in colorectal cancer.

BACKGROUND: Chemoresistance presents a significant obstacle in the treatment of colorectal cancer (CRC), yet the molecular basis underlying CRC chemoresistance remains poorly understood, impeding the development of new therapeutic interventions. Elongation factor Tu GTP binding domain containing 2 (EFTUD2) has emerged as a potential oncogenic factor implicated in various cancer types, where it fosters tumor growth and survival. However, its specific role in modulating the sensitivity of CRC cells to chemotherapy is still unclear. METHODS: Public dataset analysis and in-house sample validation were conducted to assess the expression of EFTUD2 in 5-fluorouracil (5-FU) chemotherapy-resistant CRC cells and the potential of EFTUD2 as a prognostic indicator for CRC. Experiments both in vitro, including MTT assay, EdU cell proliferation assay, TUNEL assay, and clone formation assay and in vivo, using cell-derived xenograft models, were performed to elucidate the function of EFTUD2 in sensitivity of CRC cells to 5-FU treatment. The molecular mechanism on the reciprocal regulation between EFTUD2 and the oncogenic transcription factor c-MYC was investigated through molecular docking, ubiquitination assay, chromatin immunoprecipitation (ChIP), dual luciferase reporter assay, and co-immunoprecipitation (Co-IP). RESULTS: We found that EFTUD2 expression was positively correlated with 5-FU resistance, higher pathological grade, and poor prognosis in CRC patients. We also demonstrated both in vitro and in vivo that knockdown of EFTUD2 sensitized CRC cells to 5-FU treatment, whereas overexpression of EFTUD2 impaired such sensitivity. Mechanistically, we uncovered that EFTUD2 physically interacted with and stabilized c-MYC protein by preventing its ubiquitin-mediated proteasomal degradation. Intriguingly, we found that c-MYC directly bound to the promoter region of EFTUD2 gene, activating its transcription. Leveraging rescue experiments, we further confirmed that the effect of EFTUD2 on 5-FU resistance was dependent on c-MYC stabilization. CONCLUSION: Our findings revealed a positive feedback loop involving an EFTUD2/c-MYC axis that hampers the efficacy of 5-FU chemotherapy in CRC cells by increasing EFTUD2 transcription and stabilizing c-MYC oncoprotein. This study highlights the potential of EFTUD2 as a promising therapeutic target to surmount chemotherapy resistance in CRC patients.

Case report: Differential diagnosis of highly amplified anti-CD5 CAR T cells and relapsed lymphoma cells in a patient with refractory ALK positive anaplastic large cell lymphoma.

Background: Anaplastic Large Cell Lymphoma (ALCL) is one of the most common subtypes of T-cell lymphoma. Among these, refractory and relapsed (r/r) ALK positive ALCL lacks effective therapies. The chimeric antigen receptor-modified T (CAR-T) cell therapy holds great promise as a therapeutic strategy for this disease. However, it is not known yet whether anti-CD5 CAR-T cells are sufficient for the definitive treatment of relapsed ALK+ ALCL, nor the role of accurate laboratory-based diagnoses during CAR-T treatment. Case presentation: The adolescent patient received autologous T cells containing sequences encoding VH domains specific to CD5. Following the infusion, there was an increase in both the copy number and proportion of CAR-T cells in peripheral blood. IL-6 and ferritin levels in the patient exhibited significant fluctuations, with increases of 13 and 70 folds respectively, compared to baseline after the treatment. Additionally, adverse effects were observed, including grade 4 rash, grade 1 headache, nausea, and neck-pain. Surprisingly, a relapsed disease phenotype was identified based on the results of PET/CT and histopathological analysis of the inguinal lymph node biopsy. After conducting a thorough diagnostic assessment, which included flow cytometry, next-generation sequencing (NGS), examination of immune-related gene rearrangements, and analysis of the immune repertoire of T-cell receptors (TCR), we conclusively determined that the hyperplastic T cells identified in the lymph node were the result of an expansion of CAR-T cells. Ultimately, the patient has attained complete remission (CR) and has sustained a disease-free survival state for 815 days as of the cutoff date on August 30, 2023. Conclusion: Taken together, the results demonstrate that anti-CD5 CAR-T cells can induce a clinical response in r/r ALK+ ALCL patient. Furthermore, this case underscores the importance of utilizing advanced technologies with high sensitivity and accuracy for biological detection in clinical laboratory diagnosis and prognosis in CAR-T cell treatment. Trial registration number: NCT04767308.