Patients
From August 18, 2021 to May 8, 2023, a total of 11 were infused with IMC001 CAR-T cells. All 11 patients were included in the safety analysis; 3 patients each in the low-, middle- and high- dose group, with 2 more expansion patients enrolled at the recommended dose of 1×106 cells/kg (middle-dose). Ten patients who had at least one efficacy evaluation after IMC001 infusion were included in the efficacy analysis.
Among the 11 patients in the safety analysis, 63.6% (7/11) were male, 81.8% had ≥2 organs with metastatic involvement and 18.2% (2/11) had metastasis in ≥3 organs, mainly in the lymph nodes, abdominal cavity and peritoneum, and liver and other organs (Table 1). A total of 54.5% (6/11) patients had ascites in the abdominal cavity, while 45.5% (5/11) had ascites in the pelvic cavity. All patients had received at least two lines of prior therapy (one patient failed 1st line therapy and refused a 2nd line treatment) and 27.3% (3/11) had received immunotherapy. The median duration from apheresis to infusion was 22 days (range, 16-33 days).
Table 1 Demographics and baseline characteristics (SS)
Dose group
|
Pt #
|
Sex
|
Age
|
ECOG
|
Diagnosis
|
EpCAM
H-score
|
No. of metastatic organs
|
Metastatic sites
|
Previous treatment
|
Surgery
|
Chemotherapy lines
|
Low
3×105 CAR-T cells/kg
|
1
|
F
|
47
|
1
|
Gastric adenocarcinoma of stomach body,Stage IV
|
90%
2.9
|
4
|
Pelvis, peritoneum, abdominal cavity, lymph nodes
|
Laparoscopy, peritoneal nodule biopsy
|
2
|
2
|
M
|
40
|
0
|
Distal gastric adenocarcinoma,Stage IV
|
30%
1.4
|
1
|
Lymph nodes
|
Laparoscopy, gastroduodenostomy
|
2
|
3
|
F
|
36
|
1
|
Gastric adenocarcinoma of stomach body, Stage IV
|
10%
1.05
|
2
|
Bone, pelvis
|
Hysterectomy
|
3
|
Middle
1×106 CAR-T cells/kg
|
4
|
M
|
50
|
1
|
Gastric adenocarcinoma of stomach body, Stage IV
|
10%
1.1
|
3
|
Abdominal cavity, pelvis, lymph nodes
|
Laparoscopy
|
2
|
5
|
M
|
53
|
0
|
Distal gastric adenocarcinoma,Stage IV
|
90%
2.45
|
2
|
Liver, abdominal cavity
|
Radical gastrectomy
|
2
|
6
|
M
|
66
|
0
|
Distal gastric adenocarcinoma,Stage IV
|
90%
2.15
|
2
|
Lung
|
Radical gastrectomy
|
2
|
7
|
F
|
53
|
1
|
Gastric adenocarcinoma of stomach body, Stage IV
|
100% 1.9
|
2
|
Lymph nodes, peritoneum?
|
Laparoscopy
|
1
|
8
|
M
|
60
|
1
|
Gastric adenocarcinoma of fundic gland, Stage IV
|
100% 2.8
|
1
|
Lymph nodes
|
None
|
2
|
High
3×106 CAR-T cells/kg
|
9
|
M
|
70
|
0
|
Distal gastric adenocarcinoma, Stage IV
|
100%
2.3
|
2
|
Pancreatic head/neck, lymph nodes
|
Radical gastrectomy
|
2
|
10
|
M
|
58
|
0
|
Gastric adenocarcinoma of stomach body, Stage IV
|
70%
1.5
|
2
|
Pancreatic head/neck, lymph nodes
|
Radical gastrectomy
|
2
|
11
|
F
|
36
|
0
|
Gastric adenocarcinoma, Stage IV
|
90%
1.9
|
2
|
Bilateral appendages, peritoneum
|
Bilateral appendectomy
|
2
|
CAR-T, chimeric antigen receptor; ECOG, Eastern Co-operative Oncology Group; EpCAM, epithelial cell adhesion molecule; Pt, patient.
Safety and tolerability
A DLT was reported in two patients in the high dose (3×106 cells/kg) group and the enrolment was stopped, a Grade 4 immune-related hepatitis in one patient and Grade 4 cytokine release syndrome (accompanied by COVID-19 infection) and Grade 4 immune-related pancreatitis in another patient. The low dose (3×105 cells/kg) and middle dose (1×106 cells/kg) groups prove relative safety and efficacy.
As of the analysis cut-off date (March 31st, 2024), treatment-related adverse events (TRAEs) with an incidence rate ≥10% by PT included decrease in lymphocyte count, white blood cell count, neutrophil count, and platelet count, cytokine release syndrome, fever, abnormal liver function, elevated C-reactive protein, immune-related hepatitis, epidermolysis and anemia. Hematological toxicities such as decrease in lymphocyte count, white blood cell count, neutrophil count, and platelet count were related to lymphodepletion which recorded as TRAEs by the investigators. Grade ≥3 TRAE included cytokine release syndrome, abnormal liver function, and immune-related hepatitis (Table 2).
Table 2 Summary of Treatment-Related Adverse Events (TRAE) with an Overall Incidence Rate ≥10% or an Incidence Rate ≥10% and CTCAE Grade ≥3 SS (N=11)
|
3×105 CAR-T cells/kg (N=3)
|
1×106 CAR-T cells/kg
(N=5)
|
3×106 CAR-T cells/kg (N=3)
|
Total (N=11)
|
Preferred Term (PT)
|
Any Grade
|
Grade 3 or Higher
|
Any Grade
|
Grade 3 or Higher
|
Any Grade
|
Grade 3 or Higher
|
Any Grade
|
Grade 3 or Higher
|
At least one occurrence with an incidence rate ≥10% or an incidence rate ≥10% and CTCAE ≥3 for TRAE
|
3
|
3
|
5
|
5
|
3
|
3
|
11
|
11
|
Lymphocyte count decreased
|
3
|
2
|
4
|
4
|
3
|
3
|
10
|
9
|
Neutrophil count decreased
|
3
|
2
|
4
|
2
|
2
|
0
|
9
|
4
|
White blood cell count decreased
|
3
|
3
|
2
|
2
|
3
|
2
|
8
|
7
|
Platelet count decreased
|
2
|
2
|
2
|
1
|
2
|
1
|
6
|
4
|
Cytokine release syndrome
|
1
|
0
|
2
|
1
|
2
|
2
|
5
|
3
|
Fever
|
2
|
0
|
2
|
0
|
0
|
0
|
4
|
0
|
Abnormal liver function
|
0
|
0
|
3
|
2
|
1
|
1
|
4
|
3
|
Elevated C-reactive protein
|
0
|
0
|
3
|
0
|
0
|
0
|
3
|
0
|
epidermolysis
|
0
|
0
|
0
|
0
|
2
|
0
|
2
|
0
|
Immune-related hepatitis
|
0
|
0
|
1
|
1
|
1
|
1
|
2
|
2
|
Anemia
|
0
|
0
|
0
|
0
|
2
|
0
|
2
|
0
|
CAR-T, chimeric antigen receptor; CTCAE, common terminology criteria for adverse events.
No IMC001 infusion related deaths or serious adverse events (SAEs) were reported. However, three patients (27.2%) experienced treatment emergent SAEs: respiratory failure and disseminated intravascular coagulation (33.3%, 1/3), pancreatitis (20%, 1/5) and infectious pneumonia (33.3%, 1/3), in the low-, middle-, and high-dose groups, respectively, which were considered not related to IMC001 treatment by the investigator.
A total of five patients experienced at least one CRS event, including one patient in the low-dose group (1/3, 33.3%), two patients in the middle-dose group (2/5, 40%; one of which was Grade 3) and two in the high-dose group (2/3, 66.7%; both Grade 4). Immune-related hepatitis was observed in one patient in the middle-dose group (1/5, Grade 3) and one in the high-dose group (1/3, Grade 4). Generally, CRS or immune-related hepatitis occurred in the first week of treatment administration and the majority of patients responded to supportive therapy.
Preliminary efficacy
Among ten patients included in the efficacy analysis, the ORR and DCR were 30% (3/10) and 90% (9/10), respectively (Figure 3); the median PFS was 18.1 weeks (95% CI 5.27, --) and the median OS was 33.5 weeks (95% CI 5.27, 67.77).
One patient in the low-dose group (3×105 cells/kg) achieved a PR at week 32 and received a second infusion with a higher dose of 1×106 cells/kg at week 53, who survived for 67.9 weeks since first infusion.
In the middle-dose group (1×106 cells/kg), the ORR was 40% (2/5); the median PFS was 18.1 weeks (95% CI 7.97, --) and the median OS was 55.1 weeks (95% CI 23.78, --) with a maximum follow-up time of 21.8 months. One of the patients in the middle-dose group achieved a 15% reduction in tumor size at Week 4 and a 26% reduction at Week 8. This response evolved into a confirmed PR by Week 24, culminating in a radical gastrectomy at Week 27 and, as of Week 16 post-surgery, the patient had survived for more than 22 months by the cutoff date (Figure 4). The other patient in the middle dose group achieving a PR exhibited a 48% reduction in target lesion size at Week 16. The survival times of the other two patients in the middle-dose group, who achieved stable disease (SD), were 55 weeks and 43 weeks, respectively.
Pharmacokinetics and pharmacodynamics
After a single infusion of IMC001, cell expansion and cytokine release were detected in the peripheral blood. Pharmacokinetic analysis demonstrated a dose-dependent proliferation of CAR-T cells post IMC001 infusion, with a median Cmax value of 58, 394, and 4808 copies per microgame genomic DNA for the low-does, middle-does and high-doses respectively. The median Tmax value was 7 days (7-28); and the median persistence in peripheral blood was 11days (7-56) (Figure 5A). In a further analysis, patients were categorized into two groups based on clinical response: PR (responders), and PD or SD (non-responders). Although the response group exhibited a higher median Cmax compared to the non-response group (394 vs. 90 copies per microgram genomic DNA), the difference did not reach statistical significance (Figure 5B). An analysis of cytokine release profiles post-treatment revealed no significant correlation between efficacy and serum cytokine levels (Figure 5C-5F). These results indicate that CAR-T expansion in peripheral blood correlates with dose, while the potential correlation with clinical efficacy warrants further investigation in large scale trials.
Tumor microenvironment
In our study, we investigated the correlation between the TME and the response of IMC001. Previous reports have highlighted the role of the TME, particularly stromal cells and cancer-associated fibroblasts (CAFs); their interaction with immune cells constitutes a major driver of tumor progression and therapy response23. Notably, α-smooth muscle actin (α-SMA), a marker of activated CAFs, has been implicated in tumor progression and immunosuppression. Building upon this knowledge, we performed α-SMA staining of tissue from nine patients to characterize the pattern of CAFs within the TME, categorized as poor or rich α-SMA staining24. Remarkably, all three patients who achieved a PR exhibited poor α-SMA staining. In contrast, among patients with SD or PD, only 1/6 exhibited poor α-SMA staining, while the majority (5/6) displayed a rich α-SMA staining pattern (Figure 6A, 6B). These findings suggest that the presence of poor α-SMA staining within the TME may contribute to enhanced efficacy of IMC001 therapy.
In addition to assessing the role of CAFs, we investigated the presence of CD4 positive T cells and their potential correlation with IMC001 efficacy. CD4 positive T cells play a crucial role in orchestrating immune responses within the TME and have been implicated in tumor surveillance and regulation of anti-tumor immunity. Our analysis revealed that CD4 levels were slightly higher in patients who achieved a PR compared to those with SD or PD following IMC001 therapy (Figure 6C, 6D). While the exact mechanisms underlying this observation require further elucidation, it suggests a potential association between CD4 positive T cell infiltration and favorable clinical outcomes in response to IMC001 treatment. These findings underscore the complexity of the TME and highlight the importance of investigating multiple immune cell populations to better understand the mechanisms underlying immunotherapeutic responses in advanced gastric cancer. Further studies are warranted to validate these observations and elucidate the functional significance of α-SMA staining patterns and CD4 positive T cells in the context of IMC001 therapy.