Nimotuzumab in combination with radiotherapy in high grade glioma patients

Abstract

Nimotuzumab, a humanized antibody targeting epidermal growth factor receptor, has potent anti-proliferative, anti-angiogenic, and pro-apoptotic effects in vitro and in vivo. It also reduces the number of radio-resistant CD133⁺ glioma stem cells. The antibody has been extensively evaluated in patients with advanced head and neck, glioma, lung, esophageal, pancreatic, and gastric cancer. In this single institution experience, 35 patients with anaplastic astrocytoma (AA) or glioblastoma multiforme (GBM) were treated with irradiation and 200 mg doses of nimotuzumab. The first 6 doses were administered weekly, together with radiotherapy, and then treatment continued every 21 days until 1 year. The median number of doses was 12, and the median cumulative dose was thus 2400 mg of nimotuzumab. The most frequent treatment-related toxicities were increase in liver function tests, fever, nausea, anorexia, asthenia, dizziness, and tremors. These adverse reactions were classified as mild and moderate. The median survival time was 12.4 mo or 27.0 mo for patients with GBM or AA patients, respectively, who received curative-intent radiotherapy in combination with the antibody. The survival time of a matched population treated at the same hospital with irradiation alone was decreased (median 8.0 and 12.2 mo for GBM and AA patients, respectively) compared with that of the patients who received nimotuzumab and curative-intent radiotherapy. We have thus confirmed that nimotuzumab is a very well-tolerated drug, lacking cumulative toxicity after maintenance doses. This study, in a poor prognosis population, validates the previous data of survival gain after combining nimotuzumab and radiotherapy, in newly diagnosed high-grade glioma patients.

Keywords: :

• nimotuzumab
• monoclonal antibody
• high grade glioma
• glioblastoma multiforme
• anaplastic astrocytoma
• radiotherapy

Introduction

Glioblastoma multiforme (GBM) is the most aggressive and common primary brain tumor, representing 50% of all intracranial gliomas and 25% of all intracranial tumors in adults. After diagnosis, life expectancy is typically less than 1 y and 95% of patients relapse in the first 2 y.^1-3 Treatment currently consists of maximal tumor ablation followed by radiotherapy (RT) with or without chemotherapy (CTP).⁴ The use of chemotherapy is still a matter of debate because it does not substantially affect the survival of GBM patients.^4,5

In contrast, anaplastic astrocytoma (AA), which ranks second in frequency among the intracranial primary tumors in adults, has a relatively better prognosis. Patients’ life expectancy is 24 mo and the standard of care consists of surgery, followed by RT or RT-CTP.^6,7

Epidermal growth factor receptor (EGFR) blockade as a therapy for cancer was first proposed by J Mendelssohn during the 1980s.⁸ In the past 20 y, considerable preclinical and clinical experimental evidences have demonstrated the efficacy of EGFR blockade for cancer therapy and the identification of powerful and selective inhibitors of the EGFR activation has been one of most successful areas of cancer research.^9,10

Several inhibitors of the EGFR, e.g., cetuximab, panitumumab, erlotinib, and gefitinib, have shown positive results in clinical trials.^9-13 These antibodies and small molecule therapeutics have marketing approval for the treatment of different tumor types, including advanced colorectal, head and neck and non-small cell lung cancer.^11-13

The Cuban Center of Molecular Immunology generated a murine antibody (ior egf/r3) that efficiently blocked the interaction between EGFR and its ligands.^14,15 The antibody was humanized to reduce immunogenicity and to improve its immunological effector functions (ADCC, antibody-dependent cell-mediated cytotoxicity; CDC, complement-dependent cytotoxicity).¹⁶ Nimotuzumab efficiently blocks EGFR signal transduction and has a potent anti-proliferative, anti-angiogenic, and pro-apoptotic effect in preclinical and patients’ samples.¹⁷

Significantly, in a study by Díaz-Miqueli and coworkers using U87 human glioma tumor xenografts in nude mice, nimotuzumab reduced the radio-resistant CD133⁺ tumor stem cells, impairing tumor growth progression.¹⁸ It has been suggested that brain tumor growth is dependent on the presence of a cancer stem cell niche, and, consequently, the ability to target cancer stem cells may represent an essential property of nimotuzumab.¹⁸

The antibody has also been extensively evaluated in the clinical setting in patients bearing advanced head and neck, glioma, lung, esophageal, pancreatic, and gastric cancer, among others.^19,20 Nimotuzumab currently has marketing approval for the treatment of advanced head and neck, glioma, and esophageal cancer patients in combination with irradiation or chemo-radiotherapy. More than 40 000 patients have been treated with nimotuzumab worldwide as part of clinical trials or after marketing approval in 33 countries.^19-21 Apart from other EGFR antagonists, nimotuzumab does not induce severe skin rash or hypomagnesemia.^22,23

This paper describes the results of the use of nimotuzumab in a single institution, the Calixto García Hospital, which is among the biggest teaching hospitals in Havana and one of the nationwide reference institutions for neurosurgery.

Results

From February 2005 to July 2011, 35 patients (19 male and 16 females) received nimotuzumab in combination with radiotherapy, as part of the phase 2/3 and the phase 4 study conducted at the Calixto García Hospital. Mean age was 51 y old (range 21–74). Thirty-two of these 35 cases were operated at the referred hospital, 2 patients at the Carlos J. Finlay Hospital, and 1 patient at the International Center for Neurologic Restoration, all of them located in Havana. These 3 patients were referred to the Neurosurgery Service of the Calixto García Hospital for enrollment in the clinical trial.

All patients had histological confirmation of high grade glioma; 19 were GBM patients and 16 were AA patients. All GBM patients were classified as “de novo”, since they arose primary as GBM, while two of the AAs were secondary, as two patients had confirmed low grade astrocytomas on their first surgery. In these two patients, the AA originated via dedifferentiation of a lower grade glioma. Patients’ demographics and disease characteristics are listed in Table 1.

Table 1. Patient demographic and tumor characteristics.

Variables	Number of patients	(%)
Sex
Male	19	54.3%
Female	16	45.7%
Grouped age
Younger than 40	3	8.6%
Older than 40	32	91.4%
Histology
AA	16	54.3%
GBM	19	45.7%
KPS
100–80	29	82.8%
70–50	6	17.1%
Previous surgery
Total	6	17.1%
Partial >75%	16	45.7%
Partial <75%	10	28.6%
Biopsy	3	8.6%
Radiotherapy doses
50–60 Gy	29	82.8%
<50 Gy	4	11.4%
No radiotherapy	2	5.7%

All patients received at least 1 dose of nimotuzumab and 25 completed the induction therapy consisting in 6 weekly doses of nimotuzumab. The median number of doses was 12, ranging from 3 to 21, and consequently, patients received 2400 mg of nimotuzumab as the median cumulative dose. The maximum total dose was equivalent to 4200 mg of nimotuzumab.

Twenty-five patients (14 GBM and 11 AA) received at least 5000 cGy of radiotherapy, while 10 subjects prematurely discontinued radiotherapy before receiving the 5000 cGy radiation dose.

Safety was evaluated as a primary endpoint. In total, 176 adverse events were reported. These adverse events corresponded to both histologic subtypes: 91 adverse events (51.8%) were reported in the AA group and 85 events (48.2%) were described in the GBM group. The most frequent adverse events, irrespective of the causality attribution, consisted of altered hepatic function tests, instauration or worsening of motor deficit, hair loss, seizures, headache, anorexia, behavioral disorders (irritability, anxiety and aggressiveness), fever, loss of consciousness, dysphasia, nausea, somnolence, and cough. One hundred sixty-four adverse events (93.2%) were classified as grade 1 or 2 according the National Cancer Institute’s Common Toxicity Criteria (CTC) scale, version 3.

Ninety-eight adverse events (56%) were classified as non-related to the investigational drug, while there were 78 treatment-related adverse events. The most prevalent treatment-related toxicities included increase of the liver function tests, fever, nausea, anorexia, asthenia, dizziness, tremors, chills, pruritus, hypertension, insomnia, rhinitis, somnolence, blurred vision, and behavioral disorders. These adverse reactions were classified as grade 1 or 2 regarding severity. Only one related adverse event (bronchial aspiration) was classified as grade 3. The frequency of all related adverse events according the severity grading are shown in Table 2. Skin rash was reported in two patients, one from each histological subtype. Both reactions were classified as grade 2 according its severity.

Table 2. Related adverse events classified according severity grading

	Grade 1	Grade 2	Grade 3	Total
Altered hepatic function tests	12	2		14
Fever	3	2		5
Nauseas	4	1		5
Anorexia	3			3
Asthenia	2	1		3
Dizziness	2	1		3
Tremors	2	1		3
Headache	1	1		2
Chills	2			2
Pruritus	2			2
Hypertension	1	1		2
Insomnia	2			2
Skin rash	1	1		2
Rhinitis	2			2
Somnolence	2			2
Blurred vision	1	1		2
Behavioral disorders		2		2
Bulimia	1			1
Hyperglycemia	1			1
Gain of weight		1		1
Thrombocytosis	1			1
Thrombocytopenia	1			1
Cramps	1			1
Acidity		1		1
Anemia	1			1
Arthritis		1		1
Bronchial-aspiration			1	1
Muscular weakness	1			1
Dyspnea	1			1
Hypersomnia	1			1
Hypotension	1			1
Abulia	1			1
Urinary incontinence		1		1
Cough		1		1
Leukopenia	1			1
Hoarseness	1			1
Hot flashes	1			1
Dry mouth	1			1
Sialorrhea	1			1
Total	58	19	1	78

Regarding the consequences of the adverse events, 10 adverse events (5.6%) were considered serious. Eight of these serious adverse events were not attributed to nimotuzumab since they were associated with the natural course of the disease, while one adverse event (loss of consciousness) had an unknown causality, according the principal investigator. One serious adverse event was classified as possibly related to nimotuzumab. This adverse event consisted of bronchial aspiration, which caused patient hospitalization and later death. This patient received nimotuzumab 72 h before the bronchial aspiration episode. An autopsy was not done to this particular subject and the definite cause of death could not be established.

We also evaluated the preliminary survival data from this patient set and compared it with the survival data of a similar patient population that received only surgery and radiotherapy at the same hospital. For all GBM patients treated with nimotuzumab and irradiation, the mean and median survival time was 11.38 and 11.8 mo, respectively; for the AA subjects, mean and median survival corresponded to 25.06 and 16.5 mo, respectively. For patients who received at least 5000 cGy of radiotherapy (curative intent), the mean and median survival time was 13.97 and 12.40 mo or 28.32 and 27.0 mo for those bearing GBM or AA patients, respectively.

As an aid to the preliminary assessment of whether there was a benefit after adding nimotuzumab to the standard therapy, we estimated the survival of a similar patient population (18 GBM and 16 AA patients) treated at the same hospital with conventional RT alone. Median survival time for these matched controls was 8.0 and 12.2 mo for GBM and AA subjects, respectively. GBM and AA patients that received nimotuzumab had a better survival as compared with the matched controls (stratified log-rank = 0.047).

Discussion

The prognosis of high grade glioma patients is dismal despite the progress of neurosurgery and neuro-oncology.²⁴ Even though chemo-radiotherapy is considered the state of the art for the treatment of this patient population, the preferred option is the enrollment in clinical trials with new drugs, given the inexorable fatal outcome and the poor survival of patients with GBM and AA.^4,24

EGFR is one of the most compelling targets for high grade gliomas after the demonstration of gene amplification and protein overexpression in a significant number of patients’ biopsies.^25,26 GBM tumors are also characterized by the expression of the truncated variant of the EGFR, which is constitutively active.²⁷

Here, we describe the experience of using nimotuzumab, a humanized anti-EGFR monoclonal antibody, in combination with radiotherapy, at one single institution that enrolled 35 AA and GBM patients in two clinical studies.

Temozolomide in combination with radiotherapy is the standard of care for GBM patients, since 2005.^3,4 Our patients did not receive this alkylating agent due to drug unavailability after the commercial restrictions enforced by the US embargo. Moreover, in a phase 3 clinical trial done in Germany, the combination of irradiation, temozolomide, and nimotuzumab did not significantly increase survival as compared with temozolomide and irradiation. Retrospective analyses suggest survival benefit only for those nimotuzumab-treated patients with non-methylated MGMT tumors.²¹

In our patient set, nimotuzumab was very well-tolerated in spite of the administration of a very high cumulative dose. The majority of the adverse events were classified as unrelated to nimotuzumab, but associated to the natural course of the disease. Related adverse events were in agreement with the safety profile previously described for nimotuzumab. Most frequent toxicity consisted of constitutional symptoms, infusion reactions and increase of the liver enzymes. All related adverse events, except one bronchial aspiration episode, were mild or moderate according the CTC criteria. In our series, only two patients developed skin rash. This low frequency of skin rash can be explained by two alternative hypotheses: nimotuzumab requires bivalent binding for a stable union to the cell surface and will therefore recognize mainly high EGFR expression tissues like tumors,²⁸ or that nimotuzumab binds to an epitope in the cell surface that allows the receptor to adopt its active conformation, not disrupting the basal level of EGFR signaling for normal epithelial cells.²⁹ In summary, our institutional experience supports the conclusion that nimotuzumab is notable for being better tolerated compared with other anti-EGFR drugs.

Our results also confirm that GBM and AA patients who received nimotuzumab in combination with irradiation had a better survival compared with a matched patient population treated with radiotherapy alone, at the same hospital, by the same team. Median survival time for those patients treated with curative intent radiotherapy and nimotuzumab was 12.40 and 27.0 mo for GBM and AA, while it was 8.00 and 12.2 mo, respectively for the matched controls. In the phase 2/3 study, the median survival time was 17.24 and 44.56 mo for GBM and AA patients treated with irradiation and the antibody, respectively.³⁰

Overall, our set of treated and control patients had worse survival compared with the patients from the previous randomized trial. This can be associated with the poor performance status, the reduced number of subjects with gross total resection and the high percent of older patients included in our series, which was performed mainly as part of the phase 4 study with enrollment criteria that were less restrictive.

No EGFR inhibitors have been approved so far for the treatment of high grade glioma, but several trials have evaluated the effect of adding either cetuximab or erlotinib to the treatment of patients with relapsing tumors.^31,32 Overall, the most frequent adverse events associated with cetuximab include infusion reactions, dermatologic toxicities, including acneiform rash, skin drying and fissuring, paronychial inflammation, infectious sequelae, abscess formation, cellulitis, blepharitis, conjunctivitis, keratitis/ulcerative keratitis with decreased visual acuity, cheilitis), and hypertrichosis.^32,33 This acneiform rash occurred in 76–88% of the exposed population.³⁴ Hypomagnesemia can affect up to 55% of the exposed population,³⁵ while other less frequent adverse events include cardiopulmonary arrest and interstitial lung disease. Skin rash is mild to moderate and rare after nimotuzumab, while hypomagnesemia has not been detected so far.³⁶ Erlotinib, a small EGFR tyrosine kinase inhibitor, has also been evaluated in the treatment of newly diagnosed or relapsing glioma. The most common adverse reactions (>20%) associated with this oral drug are rash, diarrhea, anorexia, fatigue, dyspnea, cough, nausea, infection, vomiting, edema, pyrexia, dyspnea, and myalgia.^37,38

On the other hand, bevacizumab (Avastin®), an anti-vascular endothelial growth factor (VEGF) antibody is approved for glioblastoma as a single agent for adult patients with progressive disease following prior therapy. The effectiveness was based on improvement in objective response rate in patients receiving bevacizumab alone or bevacizumab plus irinotecan.³⁹ In contrast, two phase 3 trials (RTOG 0825, Avaglio) using bevacizumab for the treatment of newly diagnosed glioblastoma multiforme in combination with RT and temozolomide, did not meet their primary endpoint of the demonstration of survival benefit.^40,41 No difference was found between arms for overall survival (median 16.1 vs. 15.7 mo, P = 0.11) in 637 newly diagnosed patients included in the RTOG 0825 trial. Progression-free survival (PFS) was extended in the bevacizumab arm (7.3 vs. 10.7 mo, P = 0.004), but did not reach the significance criterion.⁴⁰ For the 921 patients treated in the Avaglio study, the addition of bevacizumab improved PFS (median 10.6 vs. 6.2 mo), but not overall survival (median 16.8 vs. 16.7 mo).⁴¹

Bevacizumab-related adverse events are bleeding/hemorrhage, epistaxis, central nervous system hemorrhage, hypertension, venous and arterial thromboembolic events, wound healing complications, proteinuria, and gastrointestinal perforations. These adverse events can be up to grade 3 to 5. Nimotuzumab, in spite of reducing the VEGF production by the tumor cells,¹⁷ as a consequence of the EGFR inhibition, does not provoke the above referred adverse events.^39-41

In summary, this institution experience confirms that nimotuzumab is a very well-tolerated drug, causing no exacerbation of the radiotherapy-expected toxicity and also lacking cumulative toxicity after many maintenance doses. This result, which was found in a poor prognosis population, confirms the results of the phase 2/3 trial where a survival benefit was found after combining nimotuzumab and radiotherapy in newly diagnosed high grade glioma patients. Novel clinical trials where nimotuzumab will be combined with RT and different chemotherapeutic drugs and in which glioma patients will be selected according predictive biomarkers of efficacy are planned.

Patients and Methods

From February 2005 to July 2011, patients diagnosed with AA or GBM were enrolled in this study, which was conducted at the Neurosurgery Service of the Calixto García Hospital in Havana. These patients were included in the phase 2/3 trial and in a phase 4 study.

The most important selection criteria were: diagnosis confirmation by pathology, age older than 18 y, a KPS greater or equal to 50, and time from surgery between 4 and 6 wk. Other inclusion criteria were neutrophil count ≥1000/mm³, platelet count ≥100 × 10⁹ cells/L, hemoglobin ≥9 g/dL, serum creatinine level ≤ the upper limit of normal and ALAT (alanine aminotransferase) and ASAT (alanine aspartate transaminase) level less than 2.5 times the upper limit of normal according the institutional standards. The protocol was conducted under the principles embodied in the Helsinki Declaration. All patients expressed their willingness to participate in the study by signing a document of informed consent. The ethical committee of the hospital approved the two protocols.

Before being enrolled in the trials, all subjects had the greatest possible tumor resection, avoiding worsening of the neurological state. The degree of resection was evaluated by contrast-enhanced CT scan or MRI done before and after surgery.

After surgery, radiotherapy (RT) was given as part of the standard treatment in a dose ranging between 5000 and 6000 cGy. Daily dose was from 180 to 200 cGy and treatment was administered from Monday to Friday for 5 to 6 wk.

Nimotuzumab was administered via the antecubital vein at a dose of 200 mg diluted in 200 mL of sodium chloride for 1 h. The first 6 doses were administered weekly, together with radiotherapy. Then, treatment continued every 21 d until completing 1 y of treatment.

For the safety evaluation, patients were strictly monitored. Vital signs were taken before, during, and after 2 h of the antibody administration. Patients were repeatedly asked about any symptom and a physical exam was done before and after therapy. Hematology and blood chemistry was done at inclusion, at 8 wk (after the first 6 doses) and then every 3 mo until a year of treatment. Adverse events were classified according to the National Cancer Institute’s CTC scale, version 3.

An institutional historical control was generated to aid in the preliminary evaluation of the effect of using nimotuzumab in these patient populations. The historical control included 34 matched patients who were treated in the same hospital, by the same neurosurgeons and radiotherapists. These patients were recruited during the time elapsed between closing the phase 2/3 and opening of the phase 4 trial. Patients’ survival was estimated from the day of surgery using the Kaplan–Meier estimates and the stratified log-rank test.

Abbreviations:
AA	=	anaplastic astrocytoma
CTP	=	chemotherapy
CTC	=	common toxicity criteria
CT-scan	=	computer tomography scan
GBM	=	glioblastoma multiforme
MAb	=	monoclonal antibody
MRI	=	magnetic resonance imaging
RT	=	radiotherapy

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

10.4161/cbt.28021