Poor mobilization of autologous CD34+ peripheral blood stem cells in haematology patients undergoing autologous stem cell transplantation is associated with the presence of variants in genes implicated in clonal haematopoiesis of indeterminant potential

Analysis of Factors Affecting Hematopoietic Stem Cell Mobilization Efficiency and Early Hematopoietic Reconstruction Indicators during Autologous Peripheral Blood Hematopoietic Stem Cell Transplantation

Purpose  To analyze the factors affecting the mobilization efficiency of hematopoietic stem cells and hematopoietic reconstruction indicators during autologous peripheral hematopoietic stem cell transplantation. Methods  The clinical data of 54 patients who underwent autologous peripheral blood hematopoietic stem cell mobilization and transplantation at Xuzhou Central Hospital from May 2016 to April 2023 were retrospectively analyzed. The gender, age, disease type, mobilization regimen, number of chemotherapy sessions, G-CSF (granulocyte colony-stimulating factor) dosage, and platelet number at the time of collection were also collected. Moreover, the relationship between these indicators with mobilization results and hematopoietic reconstruction was analyzed. Results  Results showed that age, disease type, and number of collections were significantly related to the mobilization results (number of CD34+ hematopoietic stem cells). Furthermore, multivariate analysis showed that the number of collections was an independent factor affecting mobilization efficiency. Similarly, age, platelet value at the time of collection, CD34+ stem cell value during collection, white blood cell count, and number of chemotherapy times were significantly related to the time of megakaryocytic hematopoietic reconstruction. Multifactor analysis found that age and platelet count were independent factors affecting the reconstruction time of the megakaryocytic system. However, no factor was related to the time of granulocyte hematopoietic reconstruction. Conclusion  Platelet count and age when collecting hematopoietic stem cells are closely related to megakaryocytic hematopoietic reconstruction and are key indicators of early hematopoietic reconstruction after autologous hematopoietic stem cell transplantation.

The crossroads of cancer therapies and clonal hematopoiesis

The intricate interplay between Clonal Hematopoiesis (CH) and the repercussions of cancer therapies has garnered significant research focus in recent years. Previously perceived as an age-related phenomenon, CH is now closely linked to inflammation ("Inflammaging") and cancer, impacting leukemogenesis, cancer progression, and treatment responses. This review explores the complex interplay between CH and diverse cancer therapies, including chemotherapy, targeted treatments, radiation, stem cell transplants, CAR-T cell therapy, and immunotherapy, like immune checkpoint inhibitors. Notably, knowledge about post-chemotherapy CH mutation/acquisition has evolved from a de novo incident to more of a clonal selection process. Chemotherapy and radiation exposure, whether therapeutic or environmental, increases CH risk, particularly in genes like TP53 and PPM1D. Environmental toxins, especially in high-risk environments like post-disaster sites or space exploration, are associated with CH. CH affects clinical outcomes in stem cell transplant scenarios, including engraftment, survival, and t-MN development. The presence of CH also alters CAR-T cell therapy responses and impacts the efficacy and toxicity of immunotherapies. Furthermore, specific mutations like DNMT3A and TET2 thrive under inflammatory stress, influencing therapy outcomes and justifying the ongoing tailored interventions in clinical trials. This review underscores the critical need to integrate CH analysis into personalized medicine, enhancing risk assessments and refining treatment strategies. As we progress, multidisciplinary collaboration and comprehensive studies are imperative. Understanding CH's impact, especially concerning genotoxic stressors, will inform screening, surveillance, and early detection strategies, decreasing the risk of therapy-related myeloid neoplasms and revolutionizing cancer treatment paradigms.

The Impact of CD34+ Cell Collection Yields for Autologous Transplant on Survival Outcomes in Multiple Myeloma

INTRODUCTION

According to previous data, higher yields of stem-cells collected to support autologous transplantation may predict for improved outcomes. We aimed to assess the association between high stem-cells collection and survival outcomes in multiple myeloma (MM) MATERIALS AND METHODS: We reviewed all patients who underwent autologous transplantation for MM at our center over a 10-year period, and initially used a predefined threshold of 8 × 106/kg used in previous studies.

RESULTS

Six hundred twenty-one patients were analyzed. Higher mobilization did not correlate with favorable outcomes post-transplant. The most efficient mobilizers, collecting ≥8 × 106/kg (n = 478) achieved a shorter median progression-free survival (PFS) of 24.1m versus 34.5m in patients collecting 4.5 to 8 × 106/kg (n = 129). A small group (n = 14) collecting ≤4.5 × 106/kg but minimum of 2 × 106/kg to support autologous transplantation exhibited the worst outcomes (median PFS 11.4m). Further analysis of potential confounders identified greater use of bortezomib induction in the lower mobilizers, however, sensitivity analysis in patients receiving bortezomib revealed similar results- worst outcomes to the most efficient mobilizers.

CONCLUSION

Although bortezomib is not considered stem-cell toxic, it may be associated with lower stem cell collection yields. Bortezomib's efficacy at induction may partially explain the improved outcomes, however, other factors may be involved, and are discussed. We can conclude that with our large cohort and long follow-up, high stem-cell mobilization does not appear to predict for a long-term survival advantage.

[Relevance of clonal hematopoiesis for cellular therapies]

The detection of clonal hematopoiesis (CH) in patients with hematologic neoplasms who are undergoing a cellular therapy is common. The most frequently used cellular therapy procedures include autologous and allogeneic hematopoietic stem cell transplantation (HSCT) and, more recently, chimeric antigen receptor (CAR) T‑cell therapy. All three procedures differ fundamentally in terms of harvesting and manufacturing aspects as well as usage of the respective cell product. Therefore, the importance of CH in relation to the respective treatment method must be evaluated and assessed differently. In autologous HSCT, the extent of previous cytotoxic therapy significantly contributes to the high prevalence of CH. The clinically most important aspect is the development of secondary neoplasms from a pre-existing CH clone and the potential risk for enhanced cardiovascular side effects. In allogeneic HSCT, the donor selection with respect to the age largely determines the probability for the presence of CH. In this setting, the development of secondary malignancies only plays a minor role compared to the autologous HSCT. In fact, the induction of a graft versus host (GvH) or a graft versus leukemia (GvL) effect and its influence on progression-free and overall survival seem to be of possible clinical relevance. The CAR T‑cell therapy is closely linked to inflammatory reactions regarding its mode of action and the associated side effects. In this context CH might be closely linked to the effectiveness and side effects of the CAR T‑cell therapy. Initial data reported a high prevalence of CH in patients before CAR T‑cell therapy and indicated an increased rate of inflammatory side effects, although no negative effect on survival has yet been demonstrated.

Outcomes of poor peripheral blood stem cell mobilizers with multiple myeloma at the first mobilization: A multicenter retrospective study in Japan

Autologous stem cell transplantation (ASCT) remains an important therapeutic strategy for multiple myeloma; however, a proportion of patients fail to mobilize a sufficient number of peripheral blood stem cells (PBSCs) to proceed to ASCT. In the present study, we aimed to clarify the characteristics and outcomes of poor mobilizers. Clinical data on poorly mobilized patients who underwent PBSC harvest for almost 10 years were retrospectively collected from 44 institutions in the Japanese Society of Myeloma (JSM). Poor mobilizers were defined as patients with less than 2 × 106/kg of CD34+ cells harvested at the first mobilization. The proportion of poor mobilization was 15.1%. A sufficient dataset including overall survival (OS) was evaluable in 258 poor mobilizers. Overall, 92 out of 258 (35.7%) poor mobilizers did not subsequently undergo ASCT, mainly due to an insufficient number of PBSCs. Median OS from apheresis was longer for poor mobilizers who underwent ASCT than for those who did not (86.0 vs. 61.9 mon., p = 0.02). OS from the diagnosis of poor mobilizers who underwent ASCT in our cohort was similar to those who underwent ASCT in the JSM database (3y OS rate, 86.8% vs. 85.9%). In this cohort, one-third of poor mobilizers who did not undergo ASCT had relatively poor survival. In contrast, the OS improved in poor mobilizers who underwent ASCT. However, the OS of extremely poor mobilizers was short irrespective of ASCT.

Clonal hematopoiesis and its emerging effects on cellular therapies

The accumulation of somatic mutations in hematopoietic stem cells during aging, leading to clonal expansion, is linked to a higher risk of cardiovascular mortality and hematologic malignancies. Clinically, clonal hematopoiesis is associated with a pro-inflammatory phenotype of hematopoietic cells and their progeny, inflammatory conditions and a poor outcome for patients with hematologic neoplasms and solid tumors. Here, we review the relevance and complications of clonal hematopoiesis for the treatment of hematologic malignancies with cell therapeutic approaches. In autologous and allogeneic hematopoietic stem cell transplantation native hematopoietic and immune effector cells of clonal origin are transferred, which may affect outcome of the procedure. In chimeric antigen receptor modified T-cell therapy, the effectiveness may be altered by preexisting somatic mutations in genetically modified effector cells or by unmodified bystander cells harboring clonal hematopoiesis. Registry studies and carefully designed prospective trials will be required to assess the relative roles of donor- and recipient-derived individual clonal events for autologous and allogeneic cell therapies and to incorporate novel insights into therapeutic strategies.