From deadly poison to life-saving medicine: Arsenic trioxide for cancer treatment

Arsenic and arsenic trioxide are familiar to everyone. They often appear in ancient times and martial arts novels, and are commonly used poisons that kill people invisibly. Arsenic trioxide, also known as white arsenic and realgar, is mainly composed of arsenic trioxide (As2O3). It is odorless and tasteless, and it is easy to be poisoned by accidental ingestion. It was also used as a poison in the past.

The pure product of arsenic trioxide is a white frosty powder, so why is it called "Crane's Beak Red"?

This is because arsenic is mainly refined from arsenic ore, and arsenic ore in nature is often mixed with sulfur ore. The level of refining technology in ancient times was limited, and it was difficult to obtain refined arsenic trioxide. Impure arsenic contains sulfide and appears red, which the ancients associated with the top of the red-crowned crane, hence the name "Crane's Red". The silver needle poison test method commonly used in film and television dramas is also because when the silver needle comes into contact with arsenic, the sulfur-containing substances in it come into contact with silver (Ag) to generate black silver sulfide (AgS) attached to the surface of the silver needle, and the silver needle will turn black, thereby judging whether it is toxic.

Under the ancient Chinese concept of "fighting poison with poison", arsenic has been used to treat certain difficult and dangerous diseases for a long time. The Kaibao Materia Medica records that arsenic "treats all kinds of malaria, wind and phlegm in the chest and diaphragm, and can be used as an emetic"; the Compendium of Materia Medica records that it is mainly used to treat "stroke phlegm, rest diarrhea, malaria, running tooth caries, scrofula on the neck", etc.

Arsenic trioxide is used to treat cancer thanks to the efforts of modern medical workers. In the early 1970s, Han Taiyun from the Pharmacy Department of the First Affiliated Hospital of Harbin Medical University participated in a medical tour and learned that rural Chinese medicine practitioners used a compound containing arsenic, mercury and toad venom to treat lymph tuberculosis and various cancers. In 1973, Han Taiyun made these three ingredients into an injection and named it "713" solution, also known as "Cancer Spirit", which was very effective for some cancer patients. Later, Zhang Tingdong from the same hospital collaborated with Han Taiyun to focus their research on leukemia. They proposed that arsenic is the only therapeutic chemical molecule and improved "Cancer Spirit", the main ingredient of which is arsenic trioxide. In subsequent studies, they further confirmed that arsenic trioxide has a good effect in treating leukemia, especially the subtype called acute promyelocytic leukemia (APL) [1].

Currently, China has approved the use of arsenic trioxide for the treatment of APL and advanced primary liver cancer. APL has severe clinical manifestations and is prone to bleeding and embolism during onset and induction therapy, which can cause death. It was once considered the most dangerous acute leukemia. In the past three decades, due to the standardized clinical application of all-trans retinoic acid and arsenic, APL has become a leukemia that can be cured without hematopoietic stem cell transplantation [2].

It is worth noting that although arsenic trioxide is a life-saving drug for leukemia, its toxicity cannot be ignored and it must be prescribed and treated by professional medical personnel.

Acute arsenic trioxide poisoning first causes symptoms of acute gastroenteritis. Symptoms include nausea, vomiting, abdominal pain, diarrhea, and dehydration, followed by liver and gallbladder damage, toxic hepatitis, coagulation disorders, and nerve damage. In severe cases, multiple organ failure can lead to death, with a high mortality rate. If arsenic is accidentally ingested, the person should be induced to vomit immediately, and sent to the hospital for gastric lavage and emergency treatment using the special antidote dithiopropanol [3].

References

[1] Rao Yili, Run Hong, Zhang Daqing. Turning poison into medicine: the discovery of the therapeutic effect of arsenic trioxide on acute promyelocytic leukemia[J]. Science China: Life Sciences, 2013, 43(8): 700-707.

[2] Gao Jing, Chen Beilei, Dong Changhu. Progress in clinical application of arsenic trioxide in the treatment of tumors[J]. Shaanxi Medical Journal, 2015(6):758-759.

[3] Huang Binying, Liu Hua. Rescue and nursing of patients with acute arsenic trioxide poisoning in batches[J]. Chinese Journal of Nursing, 2010, 45(3): 247-248.