Assessment of Circulating Tumor DNA in Newly Diagnosed DLBCL Patients Randomly Treated By R-CHOP or R-High Dose Chemotherapy Plus Autologous Stem Cell Support

Purpose Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin's lymphoma. The association of rituximab to CHOP chemotherapy is nowadays the standard of care for de novo DLBCL patients; however 40% of these patients relapse or are refractory to treatment within 2 years. Before rituximab, patients treated by high dose chemotherapy plus autologous stem-cell support (HDT) had a significantly better outcome than by CHOP alone 1. Between 2005 and 2008, the GOELAMS 075 French multicentric clinical trial (NCT00561379) enrolled 323 de novo DLBCL patients randomly treated by R-CHOP or R-HDT, and showed that rituximab erases the survival difference between the two arms of frontline treatment 2. The main objective of this study was to evaluate circulating tumor DNA (ctDNA) concentration measured by an easy-to-collect and cost-effective method in the GOELAMS 075 de novo DLBCL patients, in regards of the two frontline treatments. Methods Plasma samples were collected at inclusion for 123 patients and 6 months after the end-of-treatment (EOT) for 50 patients in complete remission (CR) at EOT. The 123 patients were representative of the 323 eligible patients. Among the 123 patients, 68 were assigned to the R-CHOP arm and 55 to the R-HDT arm, of which, respectively, 59 and 51 achieved CR at EOT. Baseline characteristics, overall (OS) and progression free survivals were not different between randomization arms for the 123 patients. No difference in baseline characteristics was found between both studied cohorts. ctDNA concentration in ng per ml of plasma was measured as the enrichment of DNA fragments between 100 and 300 base pairs. For survival analysis, the ctDNA threshold was defined as equal to 10 times the maximum cell-free DNA concentration measured in healthy subjects. For paired samples, mutation profiles at baseline and 6 months after EOT were assessed by capture-based targeted DNA sequencing using a panel of 43 genes known to be associated to DLBCL in the literature. Intention-to-treat (ITT) analysis was performed, unless otherwise mentioned. Results Elevated ctDNA at diagnosis was found significantly associated with adverse clinical factors (R-IPI ≥3 ; number of extranodal sites ≥2), as well as intake of salvage therapy. Patients with ctDNA ≥ 54.9 ng/ml had significantly worse OS (HR=2.4, 95 th CI : 1.1-5.2 ; Pvalue=0.029). Patients with elevated ctDNA were more likely to require a salvage therapy, regardless of the randomisation arm. Only for ITT R-CHOP patients, elevated ctDNA was associated with a significantly shorter OS (HR=4.4, 95th CI : 1.6-12.3 ; Pvalue=0.004; Figure 1). Patients with elevated ctDNA who received the initially planned 8 R-CHOP cures (no salvage therapy) had a significantly worse OS than any other patients (67% deaths ; 5-years OS : 33% ; Pvalue=0.0002). Focusing on the cohort of 50 patients in CR at the EOT, we found a significant decrease of ctDNA 6 months after EOT compared to baseline only for ITT R-HDT patients (Pvalue=0.006). Noticeably, out of the 7 patients with higher ctDNA 6 months after EOT, six had been assigned to the R-CHOP arm, and five of those did not benefit salvage therapy. Mutation profiling was performed for 46 CR patients (ITT, R-CHOP, n=23 ; R-HDT, n=23) at baseline and 6 months after EOT. Mutations were detected in 48% of R-CHOP patients and 61% of R-HDT patients. The tumor mutational burden, defined as the number of gene mutations found on the total of 164 Kb sequenced, was significantly decreased 6 months after EOT only for R-HDT patients (Pvalue=0.005). The number of mutations, especially the number of new variants, and the number of deleterious and likely oncogenic variants, increased significantly in the R-CHOP arm 6 months after EOT while decreasing in the R-HDT arm (Pvalue<0.001; Figure 2). All 46 patients in CR at EOT remained in CR 5 to 10 years after treatment, except for 3 patients, who did not receive salvage therapy and relapsed more than 5 years after EOT. All 3 patients belonged to the R-CHOP arm patients with higher ctDNA 6 months after EOT compared to baseline. Conclusion Using an easy-to-measure and low-cost method, ctDNA concentration at diagnosis was shown, in an intention-to-treat analysis, to be an adverse prognostic factor only for de novo DLBCL patients treated by standard R-CHOP. Furthermore ctDNA was not significantly cleared in plasma at CR only for ITT R-CHOP patients, with the number of mutations increased 6 months after EOT compared to baseline. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Amine-Rich Coatings to Potentially Promote Cell Adhesion, Proliferation and Differentiation, and Reduce Microbial Colonization: Strategies for Generation and Characterization

Biomaterial surface modification represents an important approach to obtain a better integration of the material in surrounding tissues. Different techniques are focused on improving cell support as well as avoiding efficiently the development of infections, such as by modifying the biomaterial surface with amine groups (–NH2). Previous studies showed that –NH2 groups could promote cell adhesion and proliferation. Moreover, these chemical functionalities may be used to facilitate the attachment of molecules such as proteins or to endow antimicrobial properties. This mini-review gives an overview of different techniques which have been used to obtain amine-rich coatings such as plasma methods and adsorption of biomolecules. In fact, different plasma treatment methods are commonly used with ammonia gas or by polymerization of precursors such as allylamine, as well as coatings of proteins (for example, collagen) or polymers containing –NH2 groups (for example, polyethyleneimine). Moreover, this mini-review will present the methods used to characterize such coatings and, in particular, quantify the –NH2 groups present on the surface by using dyes or chemical derivatization methods.

Transcriptomic profiling of tissue environments critical for post-embryonic patterning and morphogenesis of zebrafish skin

Regulation of neural crest derived pigment cells and dermal cells that form skin appendages is broadly similar across vertebrate taxa. In zebrafish, organized pigment stripes and an array of calcified scales form simultaneously in the skin during post-embryonic development. Understanding mechanisms that regulate stripe patterning and dermal morphogenesis may lead to discovery of fundamental mechanisms that govern development of animal form. To learn about cell types and potential signaling interactions that govern skin patterning and morphogenesis we generated and analyzed single cell transcriptomes of skin with genetic or induced defects in pigmentation and squamation. These data reveal a previously undescribed population of ameloblast-like epidermal cells, suggest hormonal control of epithelial-mesenchymal signaling, clarify the signaling network that governs scale papillae development, and identify the hypodermis as a crucial pigment cell support environment. These analyses provide new insights into the development of skin and pigmentation and highlight the utility of zebrafish for uncovering essential features of post-embryonic development in vertebrates.

TEMPO-Oxidized Cellulose Hydrogel Fiber Cell Load, a Cell Support System Proof of Concept

The development of new cell carriers systems are crucial for application in regenerative medicine, once they deliver the cells to the injured tissue to trigger the repair and stimulate the regeneration of the new tissue, and so far various carrier systems have been investigated in this regard. Here we report on the synthesis and characterization of a new cell carrier system in fiber shape where the cells osteo-1 are incorporated into the oxidized cellulose nanofibers suspension and then complexed with calcium ions in a pulling process giving rise to the fiber loaded with cells. The microscopic images showed the success of the proposed method to incorporate the cells into the fibers. The results of the in-vitro viability tests indicated the capability of the fibers to keep the cells alive and to mineralize them, indicating that their osteogenic capability was not affected. In addition, the fiber disintegration studies showed the system is capable of releasing the cells, suggesting the potential of the fibers as a new assembled hydrogel carrier cell therapy.

Follicular Lymphoma Microenvironment: An Intricate Network Ready for Therapeutic Intervention

Follicular Lymphoma (FL), the most common indolent non-Hodgkin’s B cell lymphoma, is a paradigm of the immune microenvironment’s contribution to disease onset, progression, and heterogeneity. Over the last few years, state-of-the-art technologies, including whole-exome sequencing, single-cell RNA sequencing, and mass cytometry, have precisely dissected the specific cellular phenotypes present in the FL microenvironment network and their role in the disease. In this already complex picture, the presence of recurring mutations, including KMT2D, CREBBP, EZH2, and TNFRSF14, have a prominent contributory role, with some of them finely tuning this exquisite dependence of FL on its microenvironment. This precise characterization of the enemy (FL) and its allies (microenvironment) has paved the way for the development of novel therapies aimed at dismantling this contact network, weakening tumor cell support, and reactivating the host’s immune response against the tumor. In this review, we will describe the main microenvironment actors, together with the current and future therapeutic approaches targeting them.

The CXCL12 Crossroads in Cancer Stem Cells and Their Niche

Cancer stem cells (CSCs) are defined as a subpopulation of “stem”-like cells within the tumor with unique characteristics that allow them to maintain tumor growth, escape standard anti-tumor therapies and drive subsequent repopulation of the tumor. This is the result of their intrinsic “stem”-like features and the strong driving influence of the CSC niche, a subcompartment within the tumor microenvironment that includes a diverse group of cells focused on maintaining and supporting the CSC. CXCL12 is a chemokine that plays a crucial role in hematopoietic stem cell support and has been extensively reported to be involved in several cancer-related processes. In this review, we will provide the latest evidence about the interactions between CSC niche-derived CXCL12 and its receptors—CXCR4 and CXCR7—present on CSC populations across different tumor entities. The interactions facilitated by CXCL12/CXCR4/CXCR7 axes seem to be strongly linked to CSC “stem”-like features, tumor progression, and metastasis promotion. Altogether, this suggests a role for CXCL12 and its receptors in the maintenance of CSCs and the components of their niche. Moreover, we will also provide an update of the therapeutic options being currently tested to disrupt the CXCL12 axes in order to target, directly or indirectly, the CSC subpopulation.

MBCL-17. METASTATIC MEDULLOBLASTOMA CAN BE CURED WITHOUT EXCISION OF THE PRIMARY TUMOR: A SINGLE CENTER EXPERIENCE

INTRODUCTION Metastatic medulloblastoma is a challenging disease The current clinical approach advocates removal of the primary tumor in the posterior fossa despite evidence of metastatic disease and administer oncologic treatment within several weeks: Infants of 3–4 years are treated by tandem high dose chemotherapy with stem cell support (ACNS0334 protocol), while older children are given radiotherapy and tandem high dose chemotherapy with stem cell support (SJMB03 protocol). We postulate that a resection of the primary tumor is not obligatory, and a biopsy may suffice in order to enable prompt oncological treatment without affecting the long-term survival. PATIENTS AND METHODS Between 2010-2019 7 patients with metastatic medulloblastoma (median age 4.5, age 1–10) were treated with biopsy only, five spinal and two from the primary tumor. Six children had a concurrent VP shunt. Four presented with cord compression, and two with neurological deterioration. Four needed emergency radiotherapy. Two infants received protocol ACNS0334, five patients received protocol SJMB03. RESULTS Six patients (85%) survived; .3 patients are long term survivors (> 5 years), 2 patients are in remission for 2–3 years, one patient is on active therapy. Only 1 patient died after a late (4 years) metastatic relapse not in the posterior fossa. CONCLUSIONS Metastatic medulloblastoma can be cured without excision of the primary tumor and without mutilating surgery. Long term prognosis is probably more attributable to disease subtype and prompt oncologic treatment. This approach merits further studies and may have implications on treatment of non-metastatic tumors.