Induction Chemotherapy for Head and Neck Cancer Occur Potentially Free Carnitine Decrease

Background: Carnitine is related to malaise. Cisplatin is a cause of decreased carnitine. The purpose of this study was to elucidate the effects of one course of induction chemotherapy (IC) for head and neck cancer on blood carnitine levels, focusing on FC. Methods: This single-center prospective study investigated 20 patients diagnosed with primary head and neck cancer who underwent IC with cisplatin, docetaxel, and 5-uorouracil. FC, acylcarnitine (AC), and total carnitine (TC) levels were measured before starting therapy and on Days 7 and 21 after starting IC. In addition, malaise was evaluated before and after therapy using a visual analog scale (VAS). Results: All subjects were men and the most common primary cancer site was the hypopharynx (9 patients). FC levels before starting therapy and on Days 7 and 21 were 47.7±2.2 μM/mL, 56.7±2.2 μM/mL, and 41.1±1.9 μM/mL, respectively. Compared with before the start of therapy, FC had signicantly decreased on Day 21 (p=0.007). AC levels before starting therapy and on Days 7 and 21 were 12.5±1.2 μM/mL, 13.6±1.4 μM/mL, and 10.7±0.7 μM/mL, respectively. TC levels before starting therapy and on Days 7 and 21 were 60.2±2.5 μM/mL, 70.2±3.3 μM/mL, and 51.7±2.3 μM/mL, respectively. No signicant differences in AC, TC or VAS were seen before the start of therapy and on Day 21. Conclusions: After IC, a latent decrease in FC occurred without any absolute deciency or subjective malaise. When concurrent chemoradiotherapy is planned following IC, supportive therapy with carnitine supplementation may be appropriate.


Introduction
Carnitine is a metabolic substance involved in fat metabolism. As can be seen from the de nition of absolute de ciency as free carnitine (FC) < 36 µM/mL in the Guidelines for Diagnosis and Treatment of Carnitine De ciency 2018, 1) the blood kinetics of FC level are important. Cisplatin is a key drug in head and neck cancer treatments and is used in a variety of cases, such as induction chemotherapy (IC) and concurrent chemoradiotherapy (CCRT). However, cisplatin has an inhibitory action on organic cation/carnitine transporter 2 (OCTN2), and is known to cause a decrease in carnitine. Carnitine de ciency in turn leads to malaise, which is a common reason for the discontinuation of cancer therapy. 2) Elucidation of how IC affects blood carnitine kinetics thus has important implications. However, no reports to date have examined associations between IC for head and neck cancer and changes in blood carnitine levels. The purpose of this study was to elucidate the effects of one course of IC for head and neck cancer on blood carnitine levels, focusing on FC.

Materials And Methods
Patients and ethics Subjects were 20 patients ≥20 but <75 years old with stage III or IV-A head and neck cancer who underwent IC as the rst treatment. Eastern Cooperative Oncology Group performance status (PS) was 0-2. Exclusion criteria were: administration of levocarnitine within the past month or current prescription of levocarnitine; pregnant or breastfeeding state, or possible pregnancy for women; or being considered as unsuitable for the trial by the patient's primary care physician. The enrollment period was from August 2, 2016 to December 31, 2019. Written consent for the trial was obtained from all patients prior to enrolment. This single-center, prospective observational study was approved (approval no. 2016-058) by the Research Ethics Committee of Tokyo Medical University Hospital.

Assessments
The primary endpoint was serum carnitine level before and after IC. Total carnitine (TC) and FC were measured from collected blood. As direct measurement of acylcarnitine (AC) was di cult, AC level was

Chemotherapy regimen
For IC, cisplatin and docetaxel were intravenously infused at a dose of 60 mg/m 2 each on day 1 and 5uorouracil was intravenously infused at a dose of 600 mg/m 2 on days 1-5 for 24 h.

Statistical analysis
Tests of normality were performed for concentrations of FC, AC, and TC levels, and for VAS score. When a normal distribution was identi ed, comparisons were made using a repeated-measures analysis of variance. Data that did not follow a normal distribution were tested with the Friedman test. Items showing a signi cant difference were tested with the Bonferroni method. Statistical analysis was performed using IBM ® SPSS ® Statistics 26 (IBM Corp., Tokyo, Japan). All tests were two-sided, with values of p<0.05 taken to indicate a signi cant difference.

Patient characteristics
Patient characteristics are shown in Table 1. All patients were men, with a median age of 64 years (range, 48-73 years). The primary site was the oropharynx in 8 patients, hypopharynx in 9 patients, larynx in 2 patients, and maxillary sinus in 1 patient. The stage was Stage III in 4 patients and Stage IV in 16 patients. The therapeutic effect was complete response (CR) in 1 patient, partial response (PR) in 14 patients, stable disease (SD) in 4 patient, and progressive disease (PD) in 1 patients.

Discussion
This study investigated changes in blood carnitine levels, including FC, in patients who underwent IC for head and neck cancer. FC levels were signi cantly lower at Post IC-21 than at Pre-IC. If 2 to 3 courses of IC were to be performed, FC levels would presumably be even lower. At the same time, absolute carnitine de ciency was seen in 1 patient (5%) and relative carnitine de ciency was seen in 4 patients (20%) at Post IC-21. Although FC was signi cantly decreased compared with before the start of therapy, few patients reached absolute or relative carnitine de ciency. Therefore, the VAS score in this study also returned to nearly Pre-IC levels by Post IC-21. This is probably one reason why attention has not been focused on blood carnitine kinetics during IC. After IC, however, CCRT or surgery may be performed with the aim of achieving complete cure, and carnitine de ciency is known to occur with CCRT for head and neck cancer. 3) Globally, 3 courses of 100 mg/m 2 cisplatin are standard in chemoradiotherapy for head and neck cancer. If CCRT is performed in combination with 3 courses of cisplatin with the goal of complete cure when FC is signi cantly decreased from the Pre-IC level, development of absolute carnitine de ciency is not di cult to imagine. This could lead to exacerbation of malaise and di culty in continuing treatment. Longer duration of radiotherapy leads to worsened prognosis. 4) As FC can be supplemented with food and also with L-carnitine preparations, CCRT planned for after IC may need to begin after some form of FC supplementation has been administered.
Of the carnitine in the body, 75% is consumed orally. The rest is biosynthesized in the cardiac muscle, kidneys, and brain. [15][16][17] The main causes of carnitine de ciency are thus insu cient dietary intake and decreased muscle mass. Muscle mass is known to decrease in cancer patients. Head and neck cancer patients show a tendency for an unbalanced diet accompanied by high alcohol consumption and dysphagia due to pharyngeal tumors. Against this background, malnutrition from decreased dietary intake is seen in 25-50% of patients. [5][6][7] Despite advances in supportive therapy, dietary intake falls even further when cisplatin is used due to nausea and other adverse effects. 8) In the energy metabolism of cancer cells, a change occurs from aerobic metabolism of fatty acids to anaerobic metabolism with glycolysis. This is called the Warburg effect, in which AC is increased and FC is decreased due to incomplete β oxidation, increasing the AC/FC ratio. 9) Among our patients, absolute carnitine de ciency was seen in 3 patients (15%) and relative carnitine de ciency in 3 patients (15%) before the start of IC. Thus, carnitine de ciency appears to occur easily in head and neck cancer patients both before and during treatment.
The distribution of carnitine is related to OCTN, ATB 0,+ , OAT9, and other proteins. OCTN2 is involved mainly in carnitine transport. 10) This sodium-dependent carnitine transporter is seen in nearly all tissues in the body. [11][12][13][14] Almost all carnitine is ltered into the urine via the renal glomeruli, then reabsorbed into the body by OCTN2 expressed in the renal tubules. [15][16][17] Cisplatin blocks OCTN2 and inhibits the expression of OCTN2 distributed in tubular cells due to nephrotoxicity. 18) Cisplatin is thus an anticancer agent that increases the urinary excretion of carnitine and reduces the expression of OCTN2, causing carnitine de ciency. In our patients, elevated blood carnitine levels were seen on Post IC-7. Blood carnitine levels are reportedly temporarily elevated with the administration of anticancer agents. [19][20][21] Unfortunately, the physiological reasons for this have yet to be clari ed. One possibility has been suggested in the literature that migration of FC into cells is blocked and blood FC is temporarily elevated when anticancer agents block the OCTN2 expressed on cell membranes. 22) Despite the signi cant elevation of FC on Post IC-7 in our patients, malaise worsened on the VAS. This is thought to be because FC in blood is not e ciently used in energy production, supporting the hypothesis that FC migration into cells is blocked when anticancer agents block OCTN2. Physiological elucidation of carnitine blood kinetics is awaited.
In this study, a signi cant decrease in FC was shown after one course of IC. That is, 1 course of IC achieved a latent decrease in FC, even though no absolute carnitine de ciency developed and the VAS score had also improved to the same as Pre-IC. CCRT or surgery was performed after IC as radical treatment. These therapies require supportive treatments to be performed in the best possible general condition. In the future, we will investigate whether any difference in malaise, treatment completion rate or other parameters for CCRT are apparent between groups with and without FC supplementation after IC.
If substantial results are achieved, this could lead to the establishment of new supportive therapies.

Conclusion
The effects of IC for head and neck cancer on blood carnitine kinetics, including FC, were investigated. FC was signi cantly decreased at Post IC-21 compared with Pre-IC. After IC, FC was in a state of latent decrease. This suggests that with supportive therapy based on carnitine supplementation, CCRT or other therapy following IC can be started with the patient in better condition.

Declarations
Ethics approval and consent to participate This study was conducted in accordance with the Declaration of Helsinki and Ethical Guidelines for Clinical Research. This study was approved (approval no. 2016-058) by the Research Ethics Committee of Tokyo Medical University Hospital. informed consent was obtained from all patients or, if patients are under 18, from a parent and/or legal guardian.

Consent for publication
Not applicable.

Availability of data and materials
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Competing interests
The authors declare that they have no competing interests.

Funding
Not Applicable