CAR T-cell expansion post-GM-CSF administration
Nine patients were enrolled in cohort from May 2021 and November 2021 to receive GM-CSF therapy at Shanghai Zhaxin Traditional Chinese and Western Medicine Hospital whose clinical characteristics are shown in Table 1. The median duration of GM-CSF intervention was 15 days (4–30). The median interval between start of GM-CSF and CAR T-cell infusion was 20 days (8-126).
We serially evaluated CAR T-cell expansion in patients with GM-CSF. Seven out of nine patients (77.8%) experienced CAR T-cell expansion in peripheral blood (PB) during GM-CSF usage (Fig. 1A). The median baseline and peak CAR T cells count in PB of the seven patients with CAR T-cell expansion were 0.85×106/L (0-50.9) and 6.06×106/L (1.43-112.55). The peaks of CAR T-cell levels appeared in day 7(2–11) following the initiation of GM-CSF administration. In addition, although no increased CAR T-cell count in PB was observed in patients #8 and #9, the percentage of CAR T-cell in cerebrospinal fluid of patient #8 increased from 4.43–35.78% at day 6 and dropped to 1.38% at day 10 meanwhile GM-CSF was administrated (Fig. 1B).
The Increment Of White Blood Cells After Initial Gm-csf Administration
We found increased white blood cells in PB of all patients with GM-CSF. The median time to achieve a WBC level above 3000 cells/mm3 was 9 (1–14) days following the initiation of GM-CSF administration. Then there was only one patient (#2) whose WBC count never dropped below 3000 cells/mm3 again. In the other eight patients(88.89%), the median duration of WBC recovery was 17(3–53) days and then WBC count dropped below 3000 cells/mm3.
White blood cell count in PB of all patients gradually increased every week after GM-CSF administration. White blood cell count in PB prior to GM-CSF administration was 2.194×109/L improved to 3.839×109/L at the second week (P = 0.032, paired t-test), to 4.398×109/L at the third week (P = 0.024, paired t-test) and to 4.965×109/L at the fourth week (P = 0.025, paired t-test). Also, the increment of neutrophil, lymphocyte and CD3-CD16 + CD56 + natural killer cell was observed in PB. The mean of neutrophil count in PB every week before and after GM-CSF initiated were 1.066×109/L, 2.134×109/L, 2.239×109/L, 2.564×109/L and 2.488×109/L. There was statistically significant difference in neutrophil count between baseline and the third week (P = 0.037, paired t-test). Moreover, lymphocyte in PB was significantly increased at the third (P = 0.025, paired t-test) and fourth (P = 0.024, paired t-test) weeks compared to at the first week after GM-CSF administration. In addition, paired t-test statistical analysis revealed a significant increase in CD3-CD16 + CD56 + natural killer cell count between the first and third weeks (56.09×106/L vs 83.41×106/L, P = 0.006, paired t-test). However, there were no significant difference observed in monocyte and CD3 + cell count at the baseline and 4-week follow-up (Fig. 2).
The Administration Of Gm-csf Alleviated Inflammation Indicators In Patients
Inflammatory markers, such as cytokines, C-reactive protein (CRP) and ferritin, were monitored in this study. However, no significant increment of inflammatory markers was observed. On the contrary, the statistically significant decreases in the mean of cytokines (IL-17F, IL-1β, IL-4, TNF-α and TNF-β) and C-reactive protein (CRP) were seen at the 4-week follow-up (P > 0.05) (Figs. 3 and 4). Furthermore, we also found the serum GM-CSF level in PB of patient 7 which remained within the normal range at the 2-week follow-up (7.7, 11 and 11.8, normal range 0-39pg/ml).
Clinical Description Of Patients
A total of nine patients with ALL and NHL in the cohort, median age 39 (20–59) years old, were treated at Shanghai Zhaxin Traditional Chinese and Western Medicine Hospital. The detailed characteristics of all patients are shown in Table 1. Four patients had ALL and NHL in first to three relapse, five patients had primary refractory disease. One patient (#4) had relapsed after prior allogeneic hematopoietic stem cell transplant (allo-HSCT). Three patients (#3, 7 and 8) had undergone autologous HSCT (auto-HSCT). Three patients (#3, 7 and 9) had previously been treated with CAR T-cell. The previous times of treatments were 435 (136–1613) days. Autologous CAR T-cell were infused in 8 patients without prior allo-HSCT, while donor-derived CAR T-cell were infused in 1 post-allo-HSCT patient (#4). The median dose for CAR T-cell infusion was 1.2 (0.63–2.79) ×106 cells per kilogram of body weight.
At a median observation time of 238 (70–346) days, two patients (#1 and #9) were bridged to allo-HSCT and patient No.5 was bridged to auto-HSCT. Two patients (#1 and #4) died of infection at day 184 and 155. Cancer-related death occurred in patient No. 3 at day 70 following CAR T-cell infusion. The clinical outcomes including overall survival (OS) and adverse effects were evaluated up to date of May 12 2022. The OS at 180 days following CAR T-cell infusion was 66.67% (Fig. 5). Overall response rate (ORR) was 6/9 (66.67%).
Adverse Reactions During Gm-csf Administration
There were 4 patients who experienced fever while GM-CSF was administrated, of which two were GM-CSF related side effects, one was pneumonia and one was urinary tract infection.
From the first day of GM-CSF administration, patient #4 and #6 developed GM-CSF related fever without elevated cytokines and infection. Patient #4 experienced intermittent fever with highest temperatures up to 38.3℃ during GM-CSF treatment and patient #6 have a high temperature up to 38.4℃ during the first two days of the onset of GM-CSF administration. The patients’ body temperature was later dropped to normal range after physical cooling or loxoprofen sodium treatment. No cytokine release syndrome (CRS) or organ dysfunction or Immune Effector Cell-associated Neurotoxicity Syndrome (ICAN) was observed.
Infection occurred in two patients (2/9, 22.22%). One patient in this cohort (#2) had baseline leukopenia for 36 days and developed pneumonia for 6 days prior to GM-CSF administration (Table 1). The severity of the pneumonia in patient No. 2 was deteriorated from day 18 post-GM-CSF administration and the signs and symptoms of infection were alleviated two months later. In addition, another patient (#5) experienced mild urinary tract infection from day 5 post-GM-CSF administration.