Granulocyte-macrophage colony stimulating factor enhances efficacy of nimustine rendezvousing with temozolomide plus irradiation in patients with glioblastoma

Abstract

BACKGROUND:

Glioblastoma is the most common and most aggressive type of primary brain tumor.

OBJECTIVE:

The aim of this study was to investigate the efficacy and safety of intranasal granulocyte-macrophage colony stimulating factor (GM-CSF) administration combined with chemoradiotherapy in patients with glioblastoma who underwent surgery.

METHODS:

Ninety-two patients were randomly divided into two groups: a control group ( $n=$ 46), who received radiotherapy with adjuvant local delivery of nimustine hydrochloride (ACNU) and systemic administration of temozolomide, and an intervention group ( $n=$ 46), who received intranasal GM-CSF prior to each cycle of adjuvant chemotherapy in addition to the treatment of the control group. Karnofsky performance status (KPS) scores, progression-free survival (PFS), overall survival (OS), and adverse effects were calculated and compared between the two groups.

RESULTS:

Compared with the control group, the intervention group had longer PFS (7.8 vs. 6.9 months, $P=$ 0.016) and OS (19.2 vs. 17.1 months, $P=$ 0.045, without adjustment for interim analyses). The KPS scores were also higher in the intervention group than in the control group after 6 months (84.35 $\pm$ 8.86 vs. 80.65 $\pm$ 7.72; $t=$ 4.552, $P=$ 0.036). Furthermore, the patients in the intervention group had lower incidence of neutropenia and thrombocytopenia (8.7% vs. 29.5%, $P=$ 0.012; 8.7% vs. 18.2%, $P=$ 0.186). Other adverse events were similar in both groups, and most adverse events were grade I/II and resolved spontaneously.

CONCLUSION:

Intranasal GM-CSF enhances the efficacy of the local ACNU administration combined with oral temozolomide chemotherapy. The survival and performance status were significantly improved in patients with glioblastoma after surgery. Additionally, the GM-CSF therapy was able to reduce the occurrence of chemotherapy-related neutropenia and thrombocytopenia.

Keywords

Glioblastoma GM-CSF intranasal rendezvous chemoradiotherapy survival

1. Background

Glioblastoma is the most common and most aggressive type of primary brain tumor. Despite recent advances in surgery, radiotherapy, and chemotherapy, these strategies yield a median survival of 14.6 months, with 2- and 5-year survival rates of 27.2% and 9.8%, respectively [1], with recurrence being the main reason for poor prognosis [2]. Cancer stem cells are known to be chemoradiotherapy resistant. Thus, therapeutic strategies against cancer stem cells are essential for the accomplishment of cancer eradication [3]. Other researchers have found that cancer stem cells have the potential to create their own niche, which helps maintain the cancer stem cell phenotype and promote tumor progression [4, 5].

The existence and importance of cancer stem cells are perceived by some as controversial. Some treatment complications have arisen owing to the stemness of a rare subpopulation of tumor cells called glioblastoma stem cells or tumor-initiating cells, which have stem cell characteristics but are not necessarily derived from normal stem cells [6]. They are able to self-renew, proliferate, and differentiate into various cell types, which underlies the cellular heterogeneity in glioblastoma. Glioblastoma stem cells give rise to new tumor cells after therapeutic eradication of the bulk of the tumor [7]. Accumulating evidence supports this concept, suggesting that glioblastoma stem cells may be a primary contributing factor to tumor recurrence [8]. Indeed, glioblastoma stem cells have recently been identified as potential therapeutic targets owing to their role in tumor initiation and recurrence.

Unlike low-grade glioblastomas, the complete surgical removal of glioblastoma is impossible due to the infiltrative nature of the disease and functional vulnerability of the brain [9]. Postoperative radiotherapy with the administration of temozolomide and local delivery of ACNU is able to remove most of the residual glioblastoma cells but not the glioblastoma stem cells. The cytotoxicity of temozolomide is related to DNA methylation and the subsequent formation of O6-methylguanine (O6-MeG), followed by cell cycle arrest at the G2/M phase [10, 11]. Glioblastoma stem cells have been considered to have a less-differentiated population in malignant tissues, and they are considered responsible for the maintenance of tumor tissues as well as for the relapse of tumors after conventional treatment [12]. Glioblastoma are among the first solid cancers in which tumor cells with stem cell-like features, such as so-called cancer stem cells, were identified. These cells are slow-dividing in vivo, suggesting that cell cycle quiescence underlies the chemotherapy resistance of cancer stem cells, leading to glioblastomarelapse [11, 12].

The defining features of cancer stem cells are evolving, but for glioblastoma stem cells, it is relevant to note some shared characteristics with normal neural progenitors. These include the expression of neural stem cell markers as well as the capacity for self-renewal, long-term proliferation, and the formation of neurospheres [13]. Cancer stem cells, when compared to their non-stem cell counterparts, display much greater tumorigenic potential when injected into the brains of immunocompromised mice. Furthermore, studies from our laboratory and others have demonstrated that cancer stem cells are preferentially resistant to radiation through activation of the DNA damage checkpoint, while other studies have revealed chemoresistance [14, 15, 16]. Glioblastoma stem cells are less sensitive to temozolomide-induced cell death compared with other tissue and tumor types, with temozolomide treatment in glioblastoma cells resulting in a stem-like gene signature [17]. Current therapies for high-grade brain tumors are only palliative, which indicates a resistant population. Increasing evidence suggests that brain tumor recurrence and progression to more aggressive tumor phenotypes is due in part to the resistance of glioblastoma stem cells to radiation, chemotherapy, and anti-angiogenics. Glioblastoma stem cells express higher levels of the DNA repair enzyme O6-methylguanine-DNA-methyltransferase (MGMT), which limits the therapeutic efficacy of temozolomide [18]. Recently, many methods for influencing the growth of cancer stem cells have been introduced. From this viewpoint, the inhibition of cancer stem cells is a promising strategy for glioblastoma eradication.

Granulocyte macrophage colony-stimulating factors (GM-CSF) regulate the maturation of progenitor cells in bone marrow into differentiated granulocytes, macrophages, and B cells. Hematopoiesis is a highly proliferative dynamic process driven by multiple hematopoietic growth factors/cytokines. Granulocytes comprise the majority of white blood cells in human circulation and play an integral role in innate and adaptive immunity. In granulopoiesis, their production is mediated by a number of different growth factors, especially granulocyte-CSF (G-CSF) and GM-CSF [19]. Hematopoiesis is a complex and dynamic process orchestrated by multiple cytokines and their receptors, most notably G-CSF and GM-CSF. Treatment with GM-CSF is currently approved: (1) to accelerate myeloid recovery in patients with non-Hodgkin lymphoma (NHL), acute lymphoblastic leukemia, and Hodgkin’s disease undergoing autologous stem cell transplantation; (2) following induction chemotherapy in older adult patients with acute myeloid leukemia (AML) to shorten time to neutrophil recovery and reduce the incidence of life-threatening infections; (3) to accelerate myeloid recovery in patients undergoing allogeneic stem cell transplantation from human leukocyte antigen-matched related donors; and (4) to mobilize hematopoietic progenitor cells into peripheral blood for collection by leukapheresis [20]. In a trial for cyclophosphamide, vincristine, procarbazine, bleomycin, prednisolone, doxorubicin, and mesna administered as therapy for NHL, the use of molgramostim (GM-CSF) resulted in faster recovery from neutropenia and reduced hospitalization, although the benefit was limited to only 72% of the patients who could tolerate GM-CSF [21]. One concern is that G-CSF may accelerate the transformation of severe congenital neutropenia to myelodysplastic syndromes or AML, associated with acquired mutations in the G-CSF receptor. Transient fever and bone pain are more commonly observed in those receiving GM-CSF, while pleural and/or pericardial effusions can also occur. In clinical oncology, recombinant GM-CSF is routinely used to correct neutropenia subsequent to chemotherapy and radiation. With the use of dose-intensive chemotherapy, GM-CSF has been widely applied to minimize chemotherapy-induced myelosuppression [22]. In addition, GM-CSF has been specifically used as an anti-tumor agent with varying degrees of success [22, 23]. The expression of GM-CSF and its receptor genes within human glioblastoma specimens have been previously reported [24]. These genes were overexpressed in most malignant tumors [25]. In vivo studies have shown that GM-CSF has potent anti-tumor effects via immune stimulation [26]. Although GM-CSF is commonly used for treating chemoradiotherapy-related hematological toxicity, its impact on the outcome of glioblastoma patients remains unclear.

Treatments that substantially reduce the tumor mass by removing proliferating cells fail to cure patients because cancer stem cells are usually slow-cycling cells and are thereby insensitive to these treatments [27]. Auffinger et al. [28] provided evidence that glioblastoma cells exposed to chemotherapeutic agents are able to convert into stem-like cells, replenishing the original tumor population and leading to enhanced chemoresistance. Bao et al. [29] postulate that cell-cycle delay might represent a mechanism for genome protection in glioblastoma-initiating cells. Analogously, Yoriko Saito et al. [30] found that G-CSF cytokine treatment induces quiescent human AML leukemia stem cell (LSC) entry into the cell cycle, significantly enhances chemotherapy sensitivity, and increases the elimination of LSCs.

In an attempt to improve the efficacy of radiotherapy through the addition of chemotherapy, the aim of this study was to evaluate an approach that would allow the safe and feasible addition of GM-CSF to ACNU interstitial chemotherapy rendezvousing with temozolomide chemotherapy-plus-radiotherapy in glioblastoma patients.

2. Methods

2.1 Patients

Patients who underwent full resection by microsurgery, had histologically confirmed glioblastoma (WHO class IV), were 18–65 years old, and had a good performance status (Karnofsky performance score [KPS] $\geqslant$ 70) at two weeks post-operation were eligible for this study. Blood chemistry and hepatic and renal function were as follows: white blood cell (WBC) count $\geqslant$ 4 $\times$ 10 ${}^{9}$ /L, hemoglobin level $\geqslant$ 100 g/L, platelet count $\geqslant$ 100 $\times$ 10 ${}^{9}$ /L, aspartate transaminase (AST) level $\leqslant$ 40 IU/L, alanine transaminase (ALT) level $\leqslant$ 40 IU/L, and serum creatinine level $\leqslant$ 140 $\mu$ mol/L. O6-methylguanine DNA methyltransferase protein, methylation states, isocitrate dehydrogenase 1/isocitrate dehydrogenase 2 gene sequences and markers of glioblastoma stem cells (CD133 $+$ /Nestin) were detected. Baseline medication was recorded in all patients. Patients with multiple or disseminated tumors were excluded. In addition, the following patients were classified as ineligible: pregnant patients; patients who received insulin injection; patients who had myocardial infarctions and unstable angina pectoris within the last 2 months; and patients with mental disorders, a history of pulmonary fibrosis or interstitial pneumonia, or other forms of cancer that occurred within 5 years of the treatment period. All patients provided written informed consent. This study was approved by the Life Science Ethics Review Committee of Zhengzhou University.

2.2 Study design and treatment

This was a prospective, randomized study. In the study, a total of 92 patients were randomized into two groups: a control group ( $n=$ 46), who received radiotherapy with concomitant and adjuvant local delivery of ACNU rendezvousing with systemic administration of temozolomide, and an intervention group ( $n=$ 46), who accepted GM-CSF (intranasal drops) combined with the above rendezvous chemoradiotherapy. Gross tumor volume (GTV) was defined as the volume of primary tumors with or without enhancement on magnetic resonance imaging (MRI). Patients in the control group received ACNU (Daichi Sankyo Co., Tokyo, Japan) interstitial chemotherapy (2.5 mg/day, 3 days/week, intracapsular injection) rendezvousing with temozolomide (Merck Sharp & Dohme Ltd, United Kingdom) chemotherapy (75 mg/(m ${}^{2}$ day), 7 days/week) for six consecutive weeks during radiotherapy. A total dose of 60.0–61.2 Gy was applied to the gross tumor volume, followed by six cycles of adjuvant ACNU interstitial chemotherapy (2.5 mg/day for 3 days during each 28-day cycle) and temozolomide chemotherapy (150–200 mg/(m ${}^{2}$ day) for 5 days each 28-day cycle). An Ommaya reservoir (OR) was designed to provide percutaneous access to the tumor cavities through a silicone elastomer port connected to a catheter. All patients underwent OR implantation and intracapsular injection. Then, 2.5 mg/ml of chemotherapeutic agent (ACNU) was administrated by puncturing the OR with a 25-gauge noncoring needle. Patients received the ACNU interstitial chemotherapy (2.5 mg/day, 3 days/week, intracapsular injection) rendezvousing with temozolomide chemotherapy (75 mg/[m ${}^{2}$ day], 7 days/week) for six consecutive weeks during radiotherapy, followed by six cycles of adjuvant ACNU interstitial chemotherapy (2.5 mg/day for 3 days during each 28-day cycle) and temozolomide chemotherapy (150–200 mg/[m ${}^{2}$ day] for 5 days during each 28-day cycle) [31]. The intervention group underwent the same standard protocol as described. Additionally, they received the intranasal application of GM-CSF (3 $\mu$ g/kg/d) on the first and third days of each cycle of adjuvant chemotherapy. The GM-CSF (50 $\mu$ g/bottle) was purchased from Xiamen Tebao Biotechnology Co., Ltd.

2.3 Surveillance and follow-up

Baseline and follow-up examinations included vital signs, subjective symptoms, neurologic examination, MRI and full blood count, and hepatic and renal function. All examinations were performed before the beginning of each cycle as well as every two weeks or when they were clinically indicated during radiation and concomitant chemotherapy MRI was performed every four to eight weeks, and KPS scores were recorded post-operation at 2, 4, and 6 months. Treatment was delayed for one or two weeks for patients with a neutrophil level of $<$ 1.5 $\times$ 10 ${}^{9}$ /L or a platelet level of $<$ 100 $\times$ 10 ${}^{9}$ /L. If a cycle was delayed for two weeks due to hematological toxicity, the drug dose was reduced by 25%. Treatment response was assessed by regular enhanced MRI scans. A 25% or greater increase in tumor size, the development of new tumors, or patient worsening were treated as disease progression. Toxic effect data were also collected and included in the analysis. These toxic effects were graded in accordance with the National Cancer Institute Common Terminology for Adverse Events version 3.0.

The primary endpoint was progression-free survival (PFS), which was measured from the date of the initial operation to the date of tumor progression, death, or end of follow-up. The secondary endpoints were overall survival (OS); KPS scores at 2, 4, and 6 months; and the safety of the combination. Overall survival was estimated from the date of the initial operation to the date of the last follow-up or the patient’s death.

2.4 Statistical analysis

Baseline characteristics of the two groups were compared with $t$ -tests, Pearson’s chi-squared test, and Fisher’s exact test. The Kaplan-Meier method was used to estimate the PFS and OS distributions. The KPS scores were compared with a one-way analysis of variance. The rates of adverse events were compared using Pearson’s chi-squared test and Fisher’s exact test. The significance level was set at $P<$ 0.05 (two-sided), and the analyses were performed using SPSS version 17.0.

3. Results

3.1 Patient characteristics

Ninety-two patients were enrolled between 2009 and 2012. However, 2 patients in the control group were excluded due to grade-3 hematologic toxicity. These patients received more than 2 days of GM-CSF treatment to relieve the toxicity. Furthermore, they were treated with antibiotics, antifungal agents, GM-CSF, and red blood cell transfusions. The final patient population consisted of 90 patients, including 52 and 38 female patients. The clinical characteristics of these patients are shown in Table 1. The median age of these patients was 51.9 years old (range: 19–65 years old). There were no significant differences between these two groups with respect to baseline characteristics (Table 1).

Table 1
Characteristics of the 90 study patients at baseline

Characteristics	Control ( $n=$ 44) no. (%)	Intervention ( $n=$ 46) no. (%)	$P$ value
Gender			$P=$ 0.131
Male	28 (63.6)	24 (52.2)
Female	16 (36.4)	22 (47.8)
Age (y)	53.98 $\pm$ 10.65	49.78 $\pm$ 13.82	$P=$ 0.106
Side			$P=$ 0.135
Superiority	27 (61.4)	21 (45.7)
Non-superiority	17 (38.6)	25 (54.3)
Tumor size			$P=$ 0.581
$ï ¼ œ$ 50 cm ${}^{2}$	32 (72.7)	31 (67.4)
$\geqslant$ 50 cm ${}^{2}$	12 (27.3)	15 (32.6)
MGMT			$P=$ 0.339
Methylation	31 (70.5)	28 (60.7)
Unmethylation	13 (29.5)	18 (39.3)
MGMT protein			$P=$ 0.708
High	16 (36.4)	15 (32.6)
Low	28 (63.6)	31 (67.4)
IDH1 gene			$P=$ 0.505
Mutation	8 (18.2)	11 (23.9)
Wild	36 (81.8)	35 (76.1)
CD133 $+$ /nestin	8.53% $\pm$ 0.67%	9.65% $\pm$ 0.37%	$P=$ 0.981

Note: MGMT, O6-methylguanine-DNA methyltransferase.

3.2 Survival outcome

3.2.1 PFS and OS

The median PFS was 7.8 months for the intervention group and 6.9 months for the control group, and the difference was statistically significant ( $P=$ 0.016). The intervention group was also superior to the control group with regard to median OS (192 vs. 171 months), and this difference had borderline significance ( $P=$ 0.045) (Table 2, Fig. 1A and B).

Table 2
Survival outcome

Group	PFS (months)			OS (months)
	Median	95% CI	$p$ value	Median	95% CI	$P$ value
Control group ( $n=$ 44)	6.9	6.47–7.41	$p=$ 0.016	17.1	14.58–18.34	$P=$ 0.045
Intervention group ( $n=$ 46)	7.8	7.27–8.34		19.2	15.73–20.98

Figure 1.

Kaplan-Meier estimates of survival among the 90 study patients randomly assigned to the treatment group. The data shows the progression-free survival (PFS) and overall survival (OS) of all 90 patients. The PFS was 7.8 months for the observation group and 6.9 months for the control group ( $P=$ 0.016). The observation group was superior to the control group in terms of OS (17.1 vs 19.2 months) ( $P=$ 0.045).

3.2.2 Performance status

There was no significant difference between the intervention group and control group in terms of KPS scores at 2 months (79.13 $\pm$ 8.12 vs. 79.78 $\pm$ 7.45) and 4 months (81.96 $\pm$ 8.85 vs. 80.22 $\pm$ 7.15) after surgery ( $P>$ 0.05). However, the intervention group revealed a significantly superior KPS score (84.35 $\pm$ 8.86 vs. 80.65 $\pm$ 7.72) after 6 months ( $t=$ 4.552, $P=$ 0.036; Fig. 2).

Table 3
Chemoradiotherapy related adverse events

Adverse events	Control group ( $n=$ 44)		Intervention group ( $n=$ 46)
	Number of patients (percentage)
Fever	4	(9.1)	6	(13.0)
Fatigue	18	(40.9)	14	(30.4)
Hypersensitivity reaction	0		2	(4.3)
Nausea, vomiting	10	(22.7)	12	(26.1)
Diarrhea, constipation	7	(15.9)	6	(13.4)
Anemia	17	(38.6)	14	(30.4)
Neutropenia	13	(29.5)	4	(8.7)
Thrombocytopenia	8	(18.2)	4	(8.7)
Hemorrhage	0		0
Infection (any)	7	(15.9)	5	(10.9)
Hyponatremia	6	(13.6)	7	(15.2)
Hypokalemia	4	(9.1)	4	(8.7)
Elevated ALT	7	(15.9)	10	(21.7)
Elevated AST	5	(11.4)	5	(10.7)
Seizure	2	(4.5)	3	(6.5)
No symptoms	9	(20.5)	8	(17.4)

Note: ALT, glutamic pyruvic transaminase. AST, glutamic oxaloacetic transaminase.

Figure 2.

Significant difference in Karnofsky performance status (KPS)* between the two groups at 6 months post-operation. The observation and control groups had no significant difference in KPS scores at 2 months and 4 months after surgery. However, after 6 months, the observation group had significantly superior KPS scores ( $P=$ 0.036). The data are expressed as means $\pm$ standard deviation.

3.2.3 Adverse events

The most common adverse effects were tolerable gastrointestinal reactions (manifested as anorexia, nausea, vomiting, diarrhea, and constipation), hematological suppression (expressed as neutropenia, thrombocytopenia, and hemorrhage), liver and kidney dysfunction, and electrolyte imbalance during the intervention period (Table 3). Adverse effects were similar between the two groups regarding the incidence of gastrointestinal toxicities, liver and kidney dysfunction, electrolyte imbalance, infection, hypersensitivity reaction, and fatigue. However, neutropenia and thrombocytopenia (grade I/II) incidence significantly decreased when GM-CSF was used during each cycle of adjuvant chemotherapy, with incidences of 8.7% and 8.7%, respectively, when compared with the control group (29.5% and 18.2%, respectively) ( $X^{2}=$ 6.381, $P=$ 0.012). In addition, no grade-III/IV chemoradiotherapy-related adverse events occurred in the intervention group during the follow-up. Furthermore, no patient died of adverse events in either of the groups. All other adverse effects were self-limited and resolved soon after the cessation of treatment and well before the beginning of the subsequent treatment.

4. Discussion

This randomized clinical trial evaluated the application of the GM-CSF regimen administered during the rendezvous chemoradiotherapy for glioblastoma with the aim of enhancing chemotherapy sensitivity and increasing the elimination of glioblastoma stem cells. The results indicate that patients in the intervention group had significantly superior PFS and OS as well as better performance status, indicating that GM-CSF therapy may prevent late relapse.

Experimental evidence suggests that the presence of therapy-resistant glioblastoma stem cells could explain tumor recurrence and metastasis [32]. All patients in this clinical study underwent craniotomy microsurgical total resection of the brain tumor and received three-dimensional conformal radiotherapy rendezvous chemotherapy. However, these standard treatments fail to completely eradicate glioblastoma stem cells, which can then cause the recurrence of the disease [32]. According to our previous in vitro studies, the application of GM-CSF targeting glioblastoma stem cells could sensitize chemotherapy and thereby increase the clearance rate for glioblastoma stem cells. Granulocyte-macrophage colony stimulating factor cytokine treatment may induce quiescent glioblastoma stem cell entry into the cell cycle and significantly enhance chemotherapy sensitivity. In a therapeutic setting, the proportion of CD133 $+$ cells (normally 5%–30%) was enriched after irradiation in vivo and in vitro resulting in increased tumorigenicity in the remaining cells [31]. This is another possible reason that GM-CSF was able to enhance the therapeutic effect.

The efficacies of systemically administered GM-CSF on glioblastoma have been previously studied. In particular, in vivo studies have shown that GM-CSF has a potent anti-tumor effect via immune stimulation [33, 34]. Granulocyte-macrophage colony stimulating factor plays a critical role in the development and maturation of dendritic cells (DCs) as well as in the proliferation and activation of T cells, linking innate and acquired immune response [24] and increasing DC-mediated responses to tumor cells [35, 36]. More recently, this has been used in the treatment of a wide range of malignancies [27]. Nebiker et al. [11] further unraveled an important paradoxical colorectal cancer feature, which is represented by the favorable prognostic role of GM-CSF. It has also been proposed that GM-CSF has both immune-dependent and immune-independent antitumor activities in human colorectal cancer. The hematopoietic cytokine GM-CSF has been investigated as a monotherapy and as a component of combination therapies for melanoma [31]. Our results are consistent with the views of the above studies. In the present study, PFS and OS were significantly extended for patients who received GM-CSF therapy, and their performance status was significantly improved after the treatment.

In this study, we used GM-CSF with the minimum recommended dose according to clinical medicine standards, which is considered safe. Patients received intranasal GM-CSF treatment, which is a noninvasive and practical alternative to other forms of administration. Studies have shown that the nasal route could be used to successfully deliver drugs to the central nervous system [37]. Joseph Scafidi et al. [38] provided direct evidence that intranasal treatment is a plausible route to introduce sufficient heparin-binding EGF-like growth factor into the brain and white matter of critically ill very-preterm infants. This approach allows the GM-CSF cytokine to target the brain more directly, leading to less impact on other parts of body. Hence, it does not increase adverse events in patients.

Our study has several limitations. First, the sample size was small. Second, data were lacking on patients’ quality of life. Third, the KPS scores were measured only up to 6 months post-surgery, limiting our assessment of performance status; finally, the effects and mechanisms of GM-CSF on glioblastoma stem cells were not investigated.

5. Conclusion

This pilot study indicates that intranasal GM-CSF with rendezvous chemoradiotherapy, as a novel therapeutic approach for the prevention of glioma relapse, could enhance the efficacy of the local delivery ACNU rendezvousing with oral temozolomide chemotherapy in glioblastoma patients who receive GM-CSF prior to each cycle of adjuvant chemotherapy after surgery.

Ethics approval and consent to participate

This study was conducted in accordance with the Declaration of Helsinki. Approval was obtained from the hospital’s ethics committee. All patients provided a written informed consent form.

Funding

This work was supported by the Key Programs of Science and Technique Foundation of Henan Province (NO.212102310149).

Footnotes

Conflict of interest

The authors declare that they have no competing interests.

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Granulocyte-macrophage colony stimulating factor enhances efficacy of nimustine rendezvousing with temozolomide plus irradiation in patients with glioblastoma

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSION:

Keywords

1. Background

2. Methods

2.1 Patients

2.2 Study design and treatment

2.3 Surveillance and follow-up

2.4 Statistical analysis

3. Results

3.1 Patient characteristics

Table 1 Characteristics of the 90 study patients at baseline

3.2.1 PFS and OS

Table 2 Survival outcome

Table 3 Chemoradiotherapy related adverse events

4. Discussion

5. Conclusion

Ethics approval and consent to participate

Funding

Footnotes

Conflict of interest

References

Table 1
Characteristics of the 90 study patients at baseline

Table 2
Survival outcome

Table 3
Chemoradiotherapy related adverse events