Clinical characteristics of the study population
The Table 1 shows the 43 patients’ baseline characteristics and the CAR-T cells they initially received. There were 36 (83.7%) cases of diffuse large B-cell lymphoma, 2 (4.7%) cases of mantle cell lymphoma, 2 (4.7%) cases of follicular lymphoma, 2 (4.7%) cases of B- cell lymphoblastic lymphoma, and 1 (2.2%) case of Burkitt’s lymphoma. There were approximately three times as many men as women and the median age was 56 years (range 26-85 years). Ten patients (23.3%) had bone marrow involvement prior to CAR-T cell infusion. 23 (62.7%) patients had high tumor burden. The median number of lines of therapy prior to CAR-T cell infusion was 3 (range,1-7).
Table1 patient covariates(N=43)
|
Covariates
|
n*
|
Age,median(range)
|
56(26-85)
|
Gender, n(%)
|
|
Male
|
31(72.1)*
|
Female
|
12(27.9)*
|
Disease
|
|
DLBCL
|
36(83.7)*
|
MCL
|
2(4.7)*
|
FL
|
2(4.7)*
|
B-LBL
|
2(4.7)*
|
Burkitt
|
1(2.2)*
|
Tumor burden prior CAR-T
|
|
Low
|
16(37.2)*
|
High
|
27(62.7)*
|
Ann Arbor stage
|
|
I-II
|
8(15.4)*
|
III-IV
|
35(82.0)*
|
ECOG score
|
|
<2
|
19(44.2)*
|
≥2
|
24(55.8)*
|
Lines of prior therapies, median(range)
|
3(1-7)
|
Bone marrow infiltration
|
|
Yes
|
10(23.3)*
|
No
|
33(76.7)*
|
Baseline blood count, median(range)
|
|
LDH
|
225.3(116.4-7477.8)
|
CRP
|
4.52(0.54-341.19)
|
Ferritin
|
379(34.3-2222)
|
WBC(×10^9/L)
|
3.97(1.48-13.85)
|
Hemoglobin(g/dL)
|
109(59-145)
|
Platelet(×10^9/L)
|
154(23-670)
|
Baseline T cell subset proportions,median(range)
|
|
CD4/CD8
|
1.1(0.15-13.43)
|
Treg(%)
|
5.71(0.07-31.47)
|
Tcm in Th(%)
|
7.68(0.38-62.95)
|
Tcm in Tc(%)
|
31.88(3.17-64.77)
|
Tn in Th(%)
|
13.55(1.15-46.77)
|
Tn in Tc(%)
|
8.64(0-48.68)
|
Teff in Th(%)
|
2.88(0.16-50.38)
|
Teff in Tc(%)
|
33.43(0-79.28)
|
Tem in Th(%)
|
34.11(5.72-92)
|
Tem in Tc(%)
|
35.12(0-84.97)
|
CAR-T cell dose(×10^6/kg)
|
3.82(0.85-12.79)
|
Outcome variable
|
|
CR/PR
|
31(72.1)*
|
No response
|
12(27.9)*
|
()*, percentage; DLBCL, diffuse large B cell lymphoma; MCL, mantle cell lymphoma; FL, follicular lymphoma; B-LBL, B cell lympho-blastic lymphoma; ECOG, eastern cooperative oncology group; LDH, lactate dehydrogenase; CRP, C-reaction protein; WBC, white blood cells
|
The median dose of infused CAR-T cells was 3.82×10^6/kg (range, 0.85-12.79). The median WBC, hemoglobin, platelet, LDH, CRP and ferritin counts before lymphodepletion (baseline blood count) were 3.97×10^9/L, 109g/L, 154×10^9/L, 225.3U/L, 4.52mg/L and 379ng/ml. Before treatment, the median CD4/CD8 ratio of peripheral blood T cells were 1.1 (0.15-13.43), the median proportion of Treg cells was 5.71% (0.07-31.47), the proportion of Tcm in Th and Tc cells was 7.68% (0.38-62.95) and 31.88% (3.17-64.77), respectively. The proportion of Tn in Th and Tc cells was 13.55% (1.15-46.77) and 8.64% (0-48.68), respectively. The proportion of Teff in Th and Tc was 2.88% (0.16-50.38) and 33.43% (0-79.28), respectively. The proportion of Tem in Th and Tc cells was 34.11% (5.72-92) and 35.12% (0-84.97), respectively. 31 (72.1%) patients achieved CR or PR one to three months after CAR-T cell infusion.
Factors associated with CR and PR in r/r NHL patients after CAR-T therapy
To search for possible factors for CAR-T treatment in r/r NHL patients, we first performed univariate logistic regression analysis on patients’ clinical characteristics (Table 2), baseline hematological parameters (Table 3), and first infusion of CAR-T cells (Table 4). The results of univariate analysis showed that the patient’s baseline tumor burden, ECOG score, the proportion of Treg cells in peripheral blood T cell subsets, and the proportion of Tcm and Tn in Tc cells at diagnosis were significantly associated with remission after CAR-T cell infusion (p<0.05). As demonstrated in Figure 2B, 2C and 2D, the proportion of Treg cells, as well as Tcm and Tn in Tc, in the response group was significantly lower than in the non-response group. Although age and the proportion of Tn in Th cells showed in figure 2E present correlation with remission, the difference was not statistically significant. However, in Figure 2a, the CD4/CD8 ratio was not different between the two groups, which may be related to the small sample size.
Table2 Univariate logistic regression analyses of the clinical characteristics of r/r NHL patients associated with CR or PR
|
Variables
|
Category
|
Remission
|
No-remission
|
Z
|
P
|
Age(years)
|
|
60(46,68)#
|
46.5(41,58.5)#
|
-1.818
|
0.071
|
Gender
|
Male
|
22(70.97)
|
9(75)
|
-0.261
|
0.841
|
Female
|
9(29.03)
|
3(25)
|
Tumor burden
|
High
|
16(51.61)
|
1(8.33)
|
-2.409
|
0.043
|
Low
|
15(48.39)
|
11(91.7)
|
ECOG
|
<2
|
18(58.06)
|
1(8.33)
|
-3.396
|
0.002
|
≥2
|
13(41.94)
|
11(91.7)
|
Bone marrow infiltration
|
Yes
|
6(19.35)
|
4(33.33)
|
-0.962
|
0.495
|
No
|
25(80.65)
|
8(66.67)
|
Lines of prior therapies
|
<4
|
19(61.29)
|
3(25)
|
-1.422
|
0.174
|
≥4
|
12(38.71)
|
9(75)
|
()#inter-quartile range,percentage for other covariates
|
Table3 Univariate logistic regression analyses of the blood index of r/r NHL patients associated with CR or PR
|
Variables
|
Remission
|
No-remission
|
Z
|
P
|
WBC
|
3.53(2.57,5.93)
|
5(3.625,6.39)
|
-1.476
|
0.142
|
Hemoglobin
|
111(95,126)
|
108(90.5,118)
|
-0.555
|
0.584
|
Platelet
|
153(118,212)
|
184.5(141.25,284.75)
|
-1.489
|
0.142
|
CRP
|
4.52(1.12,26.04)
|
6.57(1.135,40.7025)
|
-0.108
|
0.926
|
Ferritin
|
321(196,535)
|
551(289,692.3)
|
-1.543
|
0.127
|
LDH
|
217.2(191,334.4)
|
334.05(231.575,484.925)
|
-1.462
|
0.149
|
()percentage
|
Table4 Univariate logistic regression analyses of the baseline information of CAR-T therapy and CAR-T cell associated with CR or PR
|
Variable
|
Remission
|
No-remission
|
Z
|
P
|
CD4/CD8
|
1.1(0.55,1.78)
|
1.14(0.4225,1.4675)
|
-0.081
|
0.947
|
Treg
|
4.99(1.05,6.84)
|
9.225(5.9875,18.76)
|
-3.222
|
0.001
|
Tcm in Th
|
7.68(4.68,16.67)
|
8.155(2.535,15.1525)
|
-0.596
|
0.565
|
Tcm in Tc
|
36.18(29.16,50.05)
|
16.67(7.1575,28.4775)
|
-3.574
|
0.000
|
Tn in Th
|
15.28(8.59,28)
|
8.07(5.8775,18.4125)
|
-1.814
|
0.071
|
Tn in Tc
|
12.77(7.01,21.34)
|
3.275(0.9625,6.3225)
|
-3.385
|
0.000
|
Tem in Th
|
34.11(24.49,49.9)
|
29.985(8.6175,51.13)
|
-1.164
|
0.254
|
Tem in Tc
|
40.19(21.6,59.47)
|
33.765(22.6,47.69)
|
-0.839
|
0.414
|
Teff in Th
|
2.84(1.4,7.09)
|
3.175(1.59,6.5975)
|
-0.271
|
0.8
|
Teff in Tc
|
33.43(18.47,52.72)
|
34.245(17.12,46.315)
|
-0.460
|
0.659
|
CAR-T cell dose(×10^6/kg)
|
4(2.05,6.65)
|
3.65(1.58,6.12)
|
-1.090
|
0.287
|
()inter-quartile range
|
|
|
|
|
Figure 2 The proportions of T cell subsets in NHL patients. A. There was no significant difference in the proportion of CD4+ and CD8+T cells between response and non-response group (p=0.6268). B. The proportion of Treg cells in the response group was significantly lower than in the non-response group (p<0.05). C-D. The proportion of Tcm and Tn in Tc cells was significantly higher than that in the non-response group (p<0.05). E. The proportion of Tn in the response group was higher than that in the non-response group, but the difference was not statistically significant (p>0.05).
Identification of independent factors influencing response to CAR-T therapy
To further identify the independent factors for response after CAR-T therapy, the statistically significant factors in the above univariate analysis (univariate logistic p<0.05) were included in the binary logistic regression analysis (Table 5). The results of the binary analysis showed that the changes in the proportions of T cell subsets collected from the patients’ peripheral blood of patients before CAR-T infusion were significant independent factors for the therapeutic effect of CAR-T cells, among which the proportions of Tcm and Tn in Tc cells significantly influenced remission (p<0.05) (Figure 3A). ROC curve results showed that the AUC of Tcm in Tc and Tn in Tc for predicting the efficacy of CAR-T cell therapy was >60%, the AUC of Tcm in Tc was 0.855(95%CI 0.737-0.9730), and the AUC of Tn in Tc was 0.836(95%CI 0.712-0.960) (Table 6) (Figure 3B).
Table5 Multiple logistic regression analysis of the variables of clinical characteristics of r/r NHL patients and CAR-T cell associated with CR or PR
|
Variable
|
B
|
Wald
|
P
|
OR
|
95CI%
|
Tumor burden
(Low=1;High=0)
|
-1.155
|
0.331
|
0.565
|
0.315
|
0.006-16.139
|
ECOG
(<2=1;≥2=0)
|
-3.116
|
3.667
|
0.056
|
0.044
|
0.002-1.076
|
Treg
(<5.71=1;≥5.71=0)
|
-1.560
|
1.583
|
0.208
|
0.210
|
0.018-2.388
|
Tcm in Tc
(<31.88=1;≥31.88=0)
|
2.934
|
3.942
|
0.047
|
18.794
|
1.038-340.137
|
Tn in Tc
(<8.64=1;≥8.64=0)
|
2.777
|
4.252
|
0.039
|
16.075
|
1.147-225.226
|
Table6 Area under the ROC curve of Tcm and Tn in Tc for predicting the outcome of lymphoma patient
|
Variable
|
AUC
|
Standard error
|
P
|
95%CI
|
Tcm in Tc
|
0.855
|
0.060
|
0.000
|
0.737-0.973
|
Tn in Tc
|
0.836
|
0.063
|
0.001
|
0.712-0.960
|
Figure 3 Discriminative ability of Tcm and Tn in Tc between CR and NR. A. Multivariate logistic regression analysis showed that Tcm and Tn in Tc were closely related to CAR-T treatment response (p<0.05). B. The ROC curve showed the ability of the T subsets to discriminate between the response and non-response groups. Tcm and Tn in Tc represented good discriminative power with AUC>0.6, respectively.
Establishment and validation of an early prediction model for CAR-T treatment response
Potential biomarkers with concurrent AUC>0.6 were identified based on the selection criteria of p<0.05 between the remission and non-remission groups. We therefore selected Tcm in Tc cells and Tn in Tc cells as predictive biomarkers of early response after CAR-T therapy. Based on the baseline percentage of Tcm and Tn in Tc cells, we developed an early prediction model of treatment effect to analyze the likelihood of remission. Then, to assess remission response in clinical practice, we developed a nomogram that could help predict the likelihood of CR and PR for each individual in clinical practice. Finally, we internally validated the original data and drew a calibration curve to further evaluate the authenticity and accuracy of the prediction model in the actual situation. The results showed good agreement between the likelihood of predicting remission and the observed early response (Figure 4A and 4B). The total scores of Tcm and Tn were calculated in the nomogram, and the ROC curve was drawn to predict the treatment effect. The AUC result was 0.914 (95%CI 0.832-0.996), showing good predictive ability (Figure 4C). The results showed that the prediction model had high sensitivity and specificity in predicting the effect of CAR-T treatment (sensitivity 83%, specificity 74.2%), and the maximum Youden index was 0.742, and the prediction results were in good agreement with the actual situation (kappa, 0.616), indicating that the model has good predictive ability and has some clinical application value.