Preventive Effect of Acetyl-L-carnitine on Oxaliplatin-induced Peripheral Neuropathy： A Randomized, Controlled, Open-label, Phase 2 Trail

1. Background 1.1 Epidemiological overview of oxaliplatin-induced peripheral neuropathy Gastrointestinal cancer is the most common malignant tumor in the world, mainly including Gastric cancer (GC), Colorectal cancer (CRC) and so on. In the past decade, with the development of diagnosis and treatment technology, the survival time of patients with gastrointestinal malignant tumors has significantly increased, among which platinum-based chemotherapy drugs play an important role. Oxaliplatin (OXA) is the third generation of platinum-based chemotherapy drugs, which is characterized by high efficiency, low toxicity and broad spectrum, and has become the main drug in the treatment of a variety of gastrointestinal malignant tumors. However, with the widespread application of oxaliplatin, its related adverse reactions have gradually become prominent. Oxaliplatin induced peripheral neuropathy (OIPN) is a dose-limiting adverse reaction, which can be usually divided into acute and chronic OIPN according to the severity of onset. Acute OIPN mainly manifests as paresthesia, such as tingling and numbness induced or aggravated by cold stimulation, which usually appears several hours after administration and disappears within a few days. Chronic OIPN is associated with dose accumulation and develops in approximately 70% of patients receiving OXA . After the cumulative OXA dose of 540-850 mg/m2, equivalent to 9-10 cycles of 85 mg/m2 or 6 cycles of 130 mg/m2, most patients had peripheral neuropathy symptoms that did not relieve between treatment intervals. In addition to tingling and numbness similar to acute OIPN, symptoms such as hypoesthesia of proprioception and/or fine touch and ataxia that seriously affect the quality of daily life can also occur.

1.2 Treatment status of oxaliplatin-induced peripheral neuropathy at home and abroad At present, the specific mechanism of OIPN is still inconclusive. Over the years, researchers have proposed a variety of possible mechanisms around Dorsal root ganglion (DRG), including: abnormal opening and closing of ion channels, activation and inactivation of transporters, nuclear dysfunction, abnormal mitochondrial DNA function, and axonal degeneration. A variety of drug studies for the prevention and treatment of OIPN have been carried out based on the above mechanisms. Only Duloxetine is recommended by the American Society of Clinical Oncology (ASCO) for moderate prevention of OIPN at present, because it often fails to achieve ideal preventive effect in clinical application due to drug side effects and efficacy.Therefore, drug withdrawal is the main option to limit the progression of OIPN when severe neuropathy occurs. According to ASCO's updated guidelines for the prevention and treatment of chemotherapy-induced peripheral neuropathy, calcium-magnesium mixture, calmangafodipir, L-carnosine , alpha-lipoic acid, ganglioside (GM-1), metformin, venlafaxine, pregabalin, vitamin E/B, minocycline and other drugs have been tried to prevent CIPN caused by oxaliplatin, but they are all in clinical trials at various stage, and none of them has been proven effective. In addition to drug therapy, there are many studies using a variety of physical therapies, such as acupuncture, cryotherapy, compression therapy, exercise therapy, etc. Traditional Chinese medicine (TCM) has adopted its unique treatment methods, such as classical prescription, self-made prescription, traditional Chinese medicine injection, acupuncture, fumigation and acupoint application, but the preventive efficacy remains unclear.

1.3 Theoretical basis for the prevention of oxaliplatin-induced peripheral neuropathy by acetyl-L-carnitine Acetyl-L-carnitine is the acetylation product of L-carnitine, which can penetrate the blood-brain barrier and decompose into acetyl group and L-carnitine after entering the central nervous system. L-carnitine plays a role in transporting long-chain fatty acids between the inner and outer membranes of mitochondria, participating in fatty acid β-oxidation and providing energy for cells. Acetyl groups are directly involved in the synthesis of acetyl coenzyme A(acetyl-CoA) and other important metabolic mediators and indirectly in the tricarboxylic acid cycle. In addition, studies have shown that acetyl groups can also act on mGlu2 receptors located in the presynaptic membrane of the posterior horn of the spinal cord to alleviate pain by reducing the release of the excitatory amino acid transmitter glutamate. L-carnitine and acetyl groups are both physiological components of the human body, so acetyl-L-carnitine has no obvious toxic and side effects. Clinical trials of acetyl-L-carnitine in China occasionally reported mild excitement, but the symptom could be eliminated by reducing the dose. The total incidence of adverse reactions was 6.84% (8/117), mainly manifested as gastrointestinal symptoms (belching, nausea, abdominal distension, dizziness, abnormal liver function, weight loss, etc.), most of them were mild (7 cases), and 1 case was moderate. There were no sequelae after remission.

At present, the approved indication of acetyl-L-carnitine in China is diabetic peripheral neuropathy. Acetyl-L-carnitine has also been used in the treatment of chemotherapy-induced peripheral neuropathy (CIPN) in small clinical studies, and the results suggest that it has good preventive effect. However, the subjects of this study were diverse, the design was not a single chemotherapy drug, and the inclusion criteria were patients who had developed peripheral neuropathy. Therefore, our study intends to simplify the study object to OIPN caused by oxaliplatin and use it in the prevention stage in order to avoid OIPN.

In summary, acetyl-L-carnitine has a mature clinical application, high safety, and low price. Some studies have suggested that it has a therapeutic effect on chemotherapy-induced peripheral neuropathy, and is worthy of further clinical research as a potential drug for the prevention of OIPN induced by oxaliplatin. 2. Research Purpose 2.1 Main Research Purpose To evaluate the efficacy of acetyl-L-carnitine in the prevention of oxaliplatin-induced chronic peripheral neuropathy (OIPN).