CD19 CAR-T pushes the tip to the front line or in the tumor immune microenvironment

As a rising star of cancer immunotherapy, CAR-T's excellent efficacy and far-reaching therapeutic potential in blood tumors are its guarantees, but at the same time, serious neurotoxicity and side effects such as CRS, as well as high recurrence and drug resistance rates are problems

Although the role and prediction of the tumor microenvironment (TME) in solid tumors has been widely studied, there are relatively few

Characteristics of the tumor immune environment, such as the presence of activated or depleted T cells, infiltration of immunomodulatory myeloid cells or other kinds of immune cells, and gene expression programs that may affect the recruitment, expansion, and activity of T cells, can actually provide an overall comprehensive view

Recently, Veracyte, a diagnostic company, published an article titled "Tumor immune contexture is a determinant of anti-CD19 CAR T cell efficacy in large B cell lymphoma" in nature's sub-journal Nature Medicine, which revealed the impact of TME on CD19 CAR-T therapy Yescarta.

Yescarta and Veracyte research results

Yescarta (axi-cel, Chinese trade name: Ekita) is the first anti-CD19 CAR T cell therapy approved for the treatment of relapsed/refractory (r/r) LBCL (large B-cell lymphoma) and the second approved CAR-T therapy

In its key clinical ZUMA I (NCT02348216), its objective response (OR) rate was 83%; (Complete response (CR) rate was 58%); 39% of patients had a sustained response (average follow-up time was 27.

Because preclinical models often fail to accurately mimic the complex mechanisms of action of immunotherapy, Veracyte conducted reverse translational studies to identify tumor-related features associated with the results of CAR T cell interventions

Here are the main findings of the study:

1. Rapid changes in immune TME characteristics after axi-cel;

2. The complete response rate of CAR T cell therapy is associated with pre-treatment TME rich in cytokines and chemokines, which favorStrial T cell participation;

3. High density of PD-1+LAG-3^+/– T cells in TME prior to treatment are associated with OR;

4. The low density of Tregs in TME before receiving treatment is associated with ≥ grade 3 neurotoxicity;

5. Overall survival in pre-treatment TME was associated with higher Immunoscore (immune score) and Immunosign 21 (21 immune-related genes);

6. The higher the depletion of T cells in TME after treatment, the lower the level of CAR T cells in circulation, which is a key correlated factor

   
   

This article will explain

Rapid changes in TME gene signaling

The study found that after receiving axis-cel treatment, the TME gene signal changed rapidly, the response T cell-related signal was rapidly upregulated, and the B cell tumor-related marker was rapidly downregulated (as shown in the figure below), forming a dynamic pattern

Figure: The evolution of TME after axi-cel infusion is associated with clinical outcomes of ZUMA 1

T cell density of TME, as well as tumor loading, is correlated with CR (complete response rate).

By comparing CR with a subset of patients with recurrence, the researchers found that cr was achieved in all patients with low tumor burden (TB) and a higher adjuvant T (Th) cell density

However, 1 patient with high TB also achieved complete remission

In addition, the study also found that when patients relapsed, TME gained an immune-harmful environment, a decrease in T cell-related markers, and an increase in tumor-associated and immunocontroduction markers, including CCR4 and CCL22

Pre-treatment immune environment associated with survival

To discover possible links between TME gene expression of chemokines, cytokines, and their receptors with T cell genes and T cell density, the researchers analyzed the correlation

Independent datasets of other patients extracted from second-line DLBCL clinical trials indicate
.

In second-line DLBCL, IL-15 and IL-18 are associated
with CD3ε gene expression.

Finally, in two separate datasets (ZUMA-1 and patients with already commercialized axi-cel), analysis of the main immune pathways associated with CR associated with non-CR revealed that in each patient group, lymphocyte co-stimulation and intercellular adhesion of white blood cells were associated with increased multiple changes, while antigen processing and peptide antigen genes associated with M2 macrophage and myelin cell activation (CD206, CD36, CD74, HLA-DM, HLA-DQ, The presentation of HLA-DRA, HLA-E, and TREM2) is associated
with a reduction in the change in multiples.

These studies have shown that by locally produced chemokines (e.
g.
, CXCL9 and CXCL14) and cytokines (e.
g.
, IL-15, IL-7, IL-18 and IL-21), the pre-treatment tumor immune environment is associated
with the presence and activity of T cells in TME.

This supports the hypothesis that
matrix production of T cell attracting chemokines and γ chain receptor cytokines may promote T cell involvement in TME is generally beneficial to CAR T cell activity.

Lower CAR T levels are associated with T cells that fail TME

Earlier studies have shown that the efficacy of axi-cel is associated with rapid CAR T cell expansion in the blood, while early CAR T cell expansion is associated
with the ratio of TB before treatment and the long-lasting response.

Here, the researchers hypothesized that TME before and after treatment might be able to predict LBCL's response
to axi-cel better than traditional prognostic markers such as activated B-cell-like (ABC) cells of origin (COO), germination center B-cell-like (GCB), or unclassified DLBCL cell subtypes.

The results showed no association between peak CAR-T cell levels and COO, and that cyclic peak CAR levels were relatively inversely correlated with TME density after Th cell therapy lacking ICs or TOX expression, which was a known marker
of T cell failure.

These results revealed an association
between poor expansion of CAR T cells in the blood and TC cells depleted by TME infiltration after treatment.

These results may suggest that systemic T-cell failure, including failure of tumor-infiltrating lymphocytes and circulating CAR T cells, is associated
with a lack of a lasting response to cell therapy.

The higher the T cell depletion in TME after treatment, the lower the level of CAR T cells in the cycle, which is a key correlated factor
in the long-lasting response.

The low density of Tregs in TME before receiving treatment is associated with ≥ grade 3 neurotoxicity

To identify the cell subsets associated with axi-cel results in ZUMA-1 patients, the researchers measured T cell density and expression levels
of B cell lineage genes for TME before treatment.

The density of Treg cells (CD3⁺CD8⁻FoxP3⁺) decreased significantly in patients who developed high-grade neurologic events NEs (level ≥3) after axi-cel, independent
of whether there was checkpoint expression.

Unexpectedly, the researchers found that Treg density was positively correlated with TME traits that favored axi-cel clinical response, which also included high CD8⁺PD-1⁺T cell density
.

Patients with high CD8⁺ PD-1⁺ T cell density and PD-1⁺ Tregs intermediate/high density (about 1/4 of all patients tested) achieved CR after axis-cel treatment without severe NEs
.

In most patients (n = 4/5) in the pre-treatment TME, Tregs were less dense, but CD8⁺ PD-1⁺ T cells were measurable and developed into ≥-3 grade NEs
after treatment.

In addition, the study also found that pre-treatment tumor invasive inactivated Th cells were positively correlated with peak CAR T cell levels, and standardized peak CAR T cell levels were also significantly correlated with pre-treatment immune scores
.

These data suggest that tumor-infiltrating lymphocyte subsets prior to treatment, such as activated CD8+ T cells and Treg cells, are associated
with differences in efficacy and neurotoxicity.

summary

In summary, this study advances an understanding of the mechanism of action of AXI-cel, linking
its properties (i.
e.
, CAR T cell efficacy, toxicity, and patient survival) to the tumor immune environment before and after treatment.

The study also highlights the third mechanism and associated circumvention effect of third-line DLBCL on axi-cel resistance, i.
e.
, its association with the tumor immune microenvironment
.

Although the sample size of this study is limited, these results to be validated suggest that immune-based therapies with therapeutic potential, such as axi-cel, should be considered in earlier treatment regimens where a greater proportion of patients have more favorable TME characteristics and a lower tumor load to potentially maximize clinical benefit and treatment potential
.

References:

M.
Kwon, R.
Bailen, L.
Lopez Corral, et al.
REAL WORLD OF EXPERIENCE AXICABTAGENE CILOLEUCEL FOR THE TREATMENT OF RELAPSED OR REFRACTORY LARGE B-CELL LYMPHOMA IN SPAIN.
The 47th Annual Meeting of the EBMT.
Abstract OS3-4.

Scholler, N.
, Perbost, R.
, Locke, F.
L.
 et al.
 Tumor immune contexture is a determinant of anti-CD19 CAR T cell efficacy in large B cell lymphoma.
 Nat Med (2022).
https://doi.
org/10.
1038/s41591-022-01916-x