Emerging Biomarkers for Monitoring Chimeric Antigen Receptor T-Cell Therapy

BACKGROUND

Chimeric antigen receptor (CAR) T-cell therapy has revolutionized treatment of hematologic malignancies and holds promise for solid tumors. While responses to CAR T-cell therapy have surpassed other available options for patients with refractory malignancies, not all patients respond the same way. The reason for this variability is not currently understood. Therefore, there is a strong need to identify characteristics of patients as well as cellular products that lead to an effective response to CAR T-cell therapy.

CONTENT

In this review, we discuss potential biomarkers that may predict clinical outcomes of CAR T-cell therapy. Based on correlative findings from clinical trials of both commercially available and early-phase products, we classify biomarkers into categories of pre- and post-infusion as well as patient and product-related markers. Among the biomarkers that have been explored, measures of disease burden both pre- and post-infusion, as well as CAR T-cell persistence post-infusion, are repeatedly identified as predictors of disease response. Higher proportions of early memory T cells at infusion appear to be favorable, and tracking T-cell subsets throughout treatment will likely be critical.

SUMMARY

There are a growing number of promising biomarkers of CAR T-cell efficacy described in the research setting, however, none of these have been validated for clinical use. Some potentially important predictors of response may be difficult to obtain routinely under the current CAR T-cell therapy workflow. A collaborative approach is needed to select biomarkers that can be validated in large cohorts and incorporated into clinical practice.

Harvest Quality, Nucleated Cell Dose and Clinical Outcomes in Bone Marrow Transplantation: A Retrospective Study

Higher doses of infused nucleated cells (NCs) are associated with improved clinical outcomes in bone marrow transplantation (BMT) recipients. Most clinicians recommend infusing at least 2.0 × 108 NCs/kg. BMT clinicians request a target NC dose, but the harvested NC dose may be below the requested NC dose even before cell processing. We conducted this retrospective study to investigate the quality of bone marrow (BM) harvest and factors that influence infused NC doses at our institution. We also correlated infused NC doses with clinical outcomes. The study population included 347 BMT recipients (median age, 11 years; range, <1 to 75 years) at the University of Minnesota between 2009 and 2019. Underlying diagnoses mainly included 39% malignant and 61% nonmalignant diagnoses. Requested, harvested, and infused NC doses, as well as cell processing data, were obtained from the Cell Therapy Laboratory; clinical outcomes data were obtained from the University of Minnesota BMT Database. BM harvests were facilitated either by our institution (61%) or by the National Marrow Donor Program (39%). Associations of infused doses with baseline characteristics were assessed using the general Wilcoxon test/Pearson's correlation coefficient. The association of infused dose with neutrophil engraftment (absolute neutrophil count >500) by day 42, platelet engraftment (>20,000) by 6 months, acute graft-versus-host disease grade II-IV, and overall survival (OS) at 5 years were evaluated using regression and Kaplan-Meier curves. The median requested NC dose was 3.0 × 108/kg (range, 2 to 8 × 108/kg), and the median harvested and infused NC doses were 4.0 × 108/kg and 3.6 × 108/kg, respectively. Only 7% of donors had a harvested dose below the minimum requested dose. Moreover, the correlation between requested doses and harvested doses was adequate, with a harvested/requested dose ratio <.5 observed in only 5% of harvests. Additionally, the harvest volume and cell processing method were significantly correlated with the infused dose. Harvest volume exceeding the median of 948 mL was related to a significantly lower infused dose (P < .01). Moreover, hydroxyethyl starch (HES)/buffy coat processing (used to reduce RBCs with major ABO incompatibility) led to a significantly lower infused dose (P < .01). Donor age (median, 19 years; range, <1 to-70 years) and sex did not significantly influence the infused dose. Finally, the infused dose was significantly correlated with neutrophil and platelet engraftment (P < .05) but not with 5-year OS (P = .87) or aGVHD (P = .33). In our program's experience, BM harvesting is efficient and meets the requested minimum dose for 93% of recipients. Harvest volume and cell process play significant roles in determining the final infused dose. Minimizing harvest volume and cell processing could lead to increased infused dose and thus improved outcomes. Moreover, a higher infused dose leads to a better rate of neutrophil and platelet engraftment but not to improved OS, which may be linked to the sample size of our study.

Signal protein-functionalized gold nanoparticles for nuclear targeting into osteosarcoma cells for use in radiosensitization experiments

The standard therapy for malignant primary bone tumors such as osteosarcoma involves major surgeries. For tumors located in difficult regions such as the pelvis, surgical intervention could lead to serious side effects for example loss of a limb and/or function, loss of bowel, bladder and sexual function as well as problems with wound healing and surgical complications. Therefore, exploring other approaches that can improve or complement current surgical techniques is important. Hence, sensitizing primary bone tumors to radiation could offer an additional strategy that could complement surgery and significantly improve survival and quality of life. Gold nanoparticles (AuNPs) have been shown to enhance radiosensitivity by increasing the local dose of radiation inside tumors. Therefore, the referred procedure of preparation and functionalization of gold nanoparticles may be used for investigation whether DNA repair inhibition in the presence of AuNPs leads to an effective radiosensitizing strategy for primary bone tumor cells and explore the mechanism of how this may be happening. In our work, we prepared gold nanoparticles and verified the relation between the size of the AuNPs and their uptake in tumor 143B cells and also investigated whether the optimal size of the AuNPs should not be smaller than the size of nuclear envelope pores (20-50 nm). Hence, two different AuNPs systems were prepared: the first one with AuNPs core size of about 5 nm (BS) and the second one with AuNPs core size of about 50 nm (ZA). For cellular AuNPs uptake enhancement, we functionalized the AuNPs with signaling peptides. For this purpose we prepared PEG-coated AuNPs functionalized with signal peptides for targeted transport into the cytoplasm (CPP) and into the cell nucleus (CPP + NLS). The toxicity of the AuNPs systems was assessed by MTS assay. We prepared stable functionalized AuNPs systems of both sizes. With the functionalizing of the AuNPs using signal peptides (CPP, NLS), the AuNPs penetrated into the cell nucleus. The referred procedure of preparation and functionalization of gold nanoparticles may be used for investigating inhibition of DNA repair in the presence of AuNPs and it could lead to new understanding in overcoming radioresistance in primary bone tumor cells.