CD22 CAR T-cell associated hematologic toxicities, endothelial activation and relationship to neurotoxicity

BACKGROUND

Hematologic toxicities, including coagulopathy, endothelial activation, and cytopenias, with CD19-targeted chimeric antigen receptor (CAR) T-cell therapies correlate with cytokine release syndrome (CRS) and neurotoxicity severity, but little is known about the extended toxicity profiles of CAR T-cells targeting alternative antigens. This report characterizes hematologic toxicities seen following CD22 CAR T-cells and their relationship to CRS and neurotoxicity.

METHODS

We retrospectively characterized hematologic toxicities associated with CRS seen on a phase 1 study of anti-CD22 CAR T-cells for children and young adults with relapsed/refractory CD22+ hematologic malignancies. Additional analyses included correlation of hematologic toxicities with neurotoxicity and exploring effects of hemophagocytic lymphohistiocytosis-like toxicities (HLH) on bone marrow recovery and cytopenias. Coagulopathy was defined as evidence of bleeding or abnormal coagulation parameters. Hematologic toxicities were graded by Common Terminology Criteria for Adverse Events V.4.0.

RESULTS

Across 53 patients receiving CD22 CAR T-cells who experienced CRS, 43 (81.1%) patients achieved complete remission. Eighteen (34.0%) patients experienced coagulopathy, of whom 16 had clinical manifestations of mild bleeding (typically mucosal bleeding) which generally subsided following CRS resolution. Three had manifestations of thrombotic microangiopathy. Patients with coagulopathy had higher peak ferritin, D-dimer, prothrombin time, international normalized ratio (INR), lactate dehydrogenase (LDH), tissue factor, prothrombin fragment F1+2 and soluble vascular cell adhesion molecule-1 (s-VCAM-1). Despite a relatively higher incidence of HLH-like toxicities and endothelial activation, overall neurotoxicity was generally less severe than reported with CD19 CAR T-cells, prompting additional analysis to explore CD22 expression in the central nervous system (CNS). Single-cell analysis revealed that in contrast to CD19 expression, CD22 is not on oligodendrocyte precursor cells or on neurovascular cells but is seen on mature oligodendrocytes. Lastly, among those attaining CR, grade 3-4 neutropenia and thrombocytopenia were seen in 65% of patients at D28.

CONCLUSION

With rising incidence of CD19 negative relapse, CD22 CAR T-cells are increasingly important for the treatment of B-cell malignancies. In characterizing hematologic toxicities on CD22 CAR T-cells, we demonstrate that despite endothelial activation, coagulopathy, and cytopenias, neurotoxicity was relatively mild and that CD22 and CD19 expression in the CNS differed, providing one potential hypothesis for divergent neurotoxicity profiles. Systematic characterization of on-target off-tumor toxicities of novel CAR T-cell constructs will be vital as new antigens are targeted.

TRIAL REGISTRATION NUMBER

NCT02315612.

Effects of extended transport on cryopreserved allogeneic hematopoietic progenitor cell (HPC) product quality and optimal methods to assess HPC stability

BACKGROUND

Since the beginning of the COVID-19 pandemic, cryopreservation of hematopoietic progenitor cell (HPC) products has been increasingly used to ensure allogeneic donor graft availability prior to recipient conditioning for transplantation. However, in addition to variables such as graft transport duration and storage conditions, the cryopreservation process itself may adversely affect graft quality. Furthermore, the optimal methods to assess graft quality have not yet been determined.

STUDY DESIGN AND METHODS

A retrospective review was performed on all cryopreserved HPCs processed and thawed at our facility from 2007 to 2020, including both those collected onsite and by the National Marrow Donor Program (NMDP). HPC viability studies were also performed on fresh products, retention vials, and corresponding final thawed products by staining for 7-AAD (flow cytometry), AO/PI (Cellometer), and trypan blue (manual microscopy). Comparisons were made using the Mann-Whitney test.

RESULTS

For HPC products collected by apheresis (HPC(A)), pre-cryopreservation and post-thaw viabilities, as well as total nucleated cell recoveries were lower for products collected by the NMDP compared to those collected onsite. However, there were no differences seen in CD34+ cell recoveries. Greater variation in viability testing was observed using image-based assays compared to flow-based assays, and on cryo-thawed versus fresh samples. No significant differences were observed between viability measurements obtained on retention vials versus corresponding final thawed product bags.

DISCUSSION

Our studies suggest extended transport may contribute to lower post-thaw viabilities, but without affecting CD34+ cell recoveries. To assess HPC viability prior to thaw, testing of retention vials offers predictive utility, particularly when automated analyzers are used.

Longitudinal transcriptional analysis of peripheral blood leukocytes in COVID-19 convalescent donors

BACKGROUND

SARS-CoV2 can induce a strong host immune response. Many studies have evaluated antibody response following SARS-CoV2 infections. This study investigated the immune response and T cell receptor diversity in people who had recovered from SARS-CoV2 infection (COVID-19).

METHODS

Using the nCounter platform, we compared transcriptomic profiles of 162 COVID-19 convalescent donors (CCD) and 40 healthy donors (HD). 69 of the 162 CCDs had two or more time points sampled.

RESULTS

After eliminating the effects of demographic factors, we found extensive differential gene expression up to 241 days into the convalescent period. The differentially expressed genes were involved in several pathways, including virus-host interaction, interleukin and JAK-STAT signaling, T-cell co-stimulation, and immune exhaustion. A subset of 21 CCD samples was found to be highly "perturbed," characterized by overexpression of PLAU, IL1B, NFKB1, PLEK, LCP2, IRF3, MTOR, IL18BP, RACK1, TGFB1, and others. In addition, one of the clusters, P1 (n = 8) CCD samples, showed enhanced TCR diversity in 7 VJ pairs (TRAV9.1_TCRVA_014.1, TRBV6.8_TCRVB_016.1, TRAV7_TCRVA_008.1, TRGV9_ENST00000444775.1, TRAV18_TCRVA_026.1, TRGV4_ENST00000390345.1, TRAV11_TCRVA_017.1). Multiplexed cytokine analysis revealed anomalies in SCF, SCGF-b, and MCP-1 expression in this subset.

CONCLUSIONS

Persistent alterations in inflammatory pathways and T-cell activation/exhaustion markers for months after active infection may help shed light on the pathophysiology of a prolonged post-viral syndrome observed following recovery from COVID-19 infection. Future studies may inform the ability to identify druggable targets involving these pathways to mitigate the long-term effects of COVID-19 infection.

TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT04360278 Registered April 24, 2020.

953 Transcriptional analysis of leukocytes from COVID convalescent donors reveals persistent activation of the innate and adaptive immune system

Background

Coronavirus disease 2019 (COVID-19) results in robust but dysregulated acute immune response characterized by pro-inflammatory cytokine production and T-cell exhaustion, but little is known concerning immune response following recovery. We assessed immune function in convalescent plasma donors (CCD) who had recovered from COVID-19.

Methods

The cellular immune response and T-cell receptor (TCR) diversity in CCD was investigated using the nCounter host response and TCR diversity panels. 270 CCD and 40 healthy donor (HD) blood samples collected 11 to 193 days after diagnosis were analyzed. The CCD samples were from 162 donors, 69 donated more than once. All HD donated only once.

Results

Many genes were differentially expressed for months following infection. Analysis of samples collected 0 to 90 days post-diagnosis found that 19 of 773 genes were differentially expressed among CCD and HD (FDR < 0.05) (figure 1a). At 90 to 120 days, 120 to 150 and >150 post-diagnosis, 13, 58 and 4 genes were differentially expressed respectively (FDR < 0.05) (figures 1b-d). At 120 to 150 days the differentially expressed genes included those in Treg differentiation, type III interferon signaling and chemokine signaling pathways. 76 genes were differently expressed at least once during the time windows described above. (Figure 1e). Among CCD, the expression of CTLA-4, ICOS, ICOSLG, OSM and CXCR4 were initially elevated but fell to HD levels at the end of the study period. The expression of LILRA6, CCR2 and CX3CR1 increased or remained elevated throughout (figure 1f).

A subset of samples departed notably from the average trend. The transcriptome of each CCD sample was scored by its similarity to the mean transcriptome of HD samples. This analysis revealed 21 CCD samples from 19 unique donors were highly perturbed from HD samples (figure 2a). Among these highly perturbed samples 80% were collected > 90 days post-diagnosis. The perturbed samples clustered into two groups, labelled P1 and P2 (figure 2b) and displayed dysregulation of distinct gene sets (figures 2c, 2d). The P1 were characterized by increased expression of genes in myeloid inflammation, type 1 interferon and innate immune signaling pathways, lower COVID antibody levels and increased T-cell receptor diversity. P2 were characterized by highly up-regulated CD44, BCL2, TGFB1, IL18BP, IL27RA, and IL11RA.

Abstract 953 Figure 1

Longitudinal trends in CCD gene expression. a-d: Differential expression results in HD vs. 4 time windows of CCD. Genes with FDR <0.1 are labeled; e: average CCD log2 fold-changes from HD over time. Color is only given for times where the Loess regression is different from the mean HD with p < 0.05; f: longitudinal results for selected genes. Orange lines connect CCD samples over time. Blue lines show inner 95% quantiles of HD samples

Abstract 953 Figure 2

CCD with more severe departure from HD gene expression. a: CCD samples (in orange) were scored for perturbation from the mean HD (in blue), and 21 highly perturbed sample subsets emerged; b: clustering of the 21 highly perturbed patients. The dendrogram was cut to define two groups. c: volcano plots comparing expression in P1 (left) and P2 (right) vs. CCD; d: longitudinal trends of selected genes perturbed in P1 and P2

Conclusions

Immune dysregulation in CCD continues at least 6 months post-infection. Some CCDs experienced marked transcriptional changes which may be the result of COVID-19 reactivation and could be responsible for long-haul syndrome.

Acknowledgements

N/A

Trial Registration

NCT04360278

References

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Ethics Approval

N/A

Consent

N/A

Abstract 737: Signficant DLX4 expression in inflammatory breast cancer tumors from African American patients

Purpose: To examine protein expression characteristics of Distal-less homeobox4 (DLX4) in inflammatory breast cancer (IBC) cases from an African-American population to determine if a) DLX4 over-expression occurs in IBC vs. normal mammary tissue and b) over-expression is associated with clinico-pathologic features such as ER, PR, HER2.

Experimental Design: Twenty nine blocks of formalin-fixed paraffin-embedded (FFPE) tissues from well-characterized human IBC cases were used for immuno-histochemical staining (IHC). Tumor tissues were from African American subjects seen at Howard University Hospital. Normal breast tissues from 30 mammoplasties were controls. IHC results were assigned intensity and percentage scores based upon intensity of positive staining and % of stained cells. Percentage scores were assigned as 0, 1 (0%-25%), 2 (26%-50%), 3 (51%-75%) or 4 (76%-100%) and intensity scores were assigned 0, 1+, 2+ or 3+. For the analysis of the IHC, a percentage score of 3 or 4 was considered high and an intensity score of 2+ or 3+ was categorized as high. Chi-square and Fisher’s exact tests were used for analysis.

Results: The staining pattern for the categorized cohort in which 82.8% (24 out of 29) of IBC cases showed high percentages of positive cells staining for DLX4 protein, while 40.0% (12 out of 30) normal breast tissues demonstrated DLX4 expression (P=0.001). In terms of staining intensity, 75.9% (22 out of 29) of IBC cases showed a high level of intensity, compared to 20.0% (6 out of 30) of normal breast tissues (P&lt;0.001). In terms of the association between breast cancer characteristics and IHC staining, intensity of DLX4 was higher in HER2- (87.0%, 20 out of 23) than HER2+ (33.3%, 2 out of 6; P=0.018). Other associations were not statistically significant in this pilot study.

Conclusions: DLX4 expression is significantly higher in this pilot study of IBC cases from AA patients than in normal breast tissue cases. In addition, HER2- is associated with high intensity of DLX4 expression in IBC.

Associations DLX4 protein expression (IHC) In IBC and normal breast tissuesLowHighP-valuePercent positivityn (%)n (%)Controls (n=30)18 (60.0)12 (40.0)0.001IBCs (n=29)5 (17.2)24 (82.8)Staining intensityn (%)n (%)Controls (n=30)24 (80.0)6 (20.0)&lt;0.001IBCs (n=29)7 (24.1)22 (75.9)

Citation Format: Jaehong Jeong, Tammey Naab, Martin Ongkeko, Kepher Makambi, Farhan A. Khan, Jan Blancato. Signficant DLX4 expression in inflammatory breast cancer tumors from African American patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 737. doi:10.1158/1538-7445.AM2017-737