Clinical data | |
---|---|
Pronunciation | /ˌdɒksəˈruːbɪsɪn/ |
Trade names | Adriamycin, Caelyx, [1] Myocet, [2] others |
Biosimilars | Zolsketil pegylated liposomal, [3] Celdoxome pegylated liposomal [4] |
AHFS/Drugs.com | Monograph |
MedlinePlus | a682221 |
License data |
|
Pregnancy category |
|
Routes of administration | intravenous, intravesical |
ATC code | |
Legal status | |
Legal status | |
Pharmacokinetic data | |
Bioavailability | 5% (by mouth) |
Protein binding | 75% [8] |
Metabolism | Liver |
Elimination half-life | Triphasic; 12 minutes, 3.3 hours, 30 hours. Mean: 1–3 hours [8] [9] |
Excretion | Urine (5–12%), faeces (40–50%) [8] |
Identifiers | |
| |
CAS Number |
|
PubChem CID | |
IUPHAR/BPS | |
DrugBank |
|
ChemSpider | |
UNII |
|
KEGG | |
ChEBI |
|
ChEMBL |
|
CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.041.344 |
Chemical and physical data | |
Formula | C27H29NO11 |
Molar mass | 543.525 g·mol−1 |
3D model (JSmol) | |
| |
| |
(what is this?) (verify) |
Doxorubicin, sold under the brand name Adriamycin among others, is a chemotherapy medication used to treat cancer. [10] This includes breast cancer, bladder cancer, Kaposi's sarcoma, lymphoma, and acute lymphocytic leukemia. [10] It is often used together with other chemotherapy agents. [10] Doxorubicin is given by injection into a vein. [10]
Common side effects include hair loss, bone marrow suppression, vomiting, rash, and inflammation of the mouth. [10] Other serious side effects may include allergic reactions such as anaphylaxis, heart damage, tissue damage at the site of injection, radiation recall, and treatment-related leukemia. [10] People often experience red discoloration of the urine for a few days. [10] Doxorubicin is in the anthracycline and antitumor antibiotic family of medications. [10] It works in part by interfering with the function of DNA. [11]
Doxorubicin was approved for medical use in the United States in 1974. [10] It is on the World Health Organization's List of Essential Medicines. [12] [13] Versions that are pegylated and in liposomes are also available; however, they are more expensive. [13] Doxorubicin was originally made from the bacterium Streptomyces peucetius . [14]
In the EU doxorubicin pegylated liposomal (as Caelyx) is indicated to treat breast cancer, ovarian cancer, and AIDS-related Kaposi's sarcoma. It is indicated to treat multiple myeloma in combination with bortezomib. [1] Doxorubicin hydrochloride (as Myocet liposomal) is indicated to treat breast cancer in combination with cyclophosphamide. [2]
Doxorubicin is commonly used to treat some leukemias and lymphomas, as well as cancers of the bladder, breast, stomach, lung, ovaries, thyroid, soft tissue sarcoma as well as aggressive fibromatosis (desmoid tumor), multiple myeloma, and others. [9] [15] [16] Commonly used doxorubicin-containing regimens are AC (Adriamycin, cyclophosphamide), TAC (taxotere, AC), ABVD (Adriamycin, bleomycin, vinblastine, dacarbazine), BEACOPP, CHOP (cyclophosphamide, hydroxydaunorubicin, vincristine, prednisone) and FAC (5-fluorouracil, adriamycin, cyclophosphamide). [9] Its activity is inhibited by certain antioxidant plant extracts, for example Tragia volubilis aqueous extract. [17]
Doxil (see below) is used primarily for the treatment of ovarian cancer where the disease has progressed or recurred after platinum-based chemotherapy, or for the treatment of AIDS-related Kaposi's sarcoma. [18]
The most dangerous side effect of doxorubicin is dilated cardiomyopathy, leading to congestive heart failure. The rate of cardiomyopathy is dependent on its cumulative dose, with an incidence about 4% when the dose of doxorubicin is 500–550 mg/m2, 18% when the dose is 551–600 mg/m2 and 36% when the dose exceeds 600 mg/m2. [19] There are several ways in which doxorubicin is believed to cause cardiomyopathy, including oxidative stress due to iron accumulation, downregulation of genes for contractile proteins, and p53-mediated apoptosis. [19] [20]
Doxorubicin-induced cardiomyopathy typically results in dilated cardiomyopathy, with all four cardiac chambers being enlarged. [21] This results in both systolic and diastolic dysfunction. [21] Eventually, heart failure can result, which carries a 50% mortality rate. [21] There is no effective treatment against established cardiomyopathy caused by the drug as of 2010. [21] The drug dexrazoxane, which is an iron chelator may be used to decrease the risk of doxorubicin's cardiotoxicity in certain cases. [22]
Another common and potentially fatal complication of doxorubicin is typhlitis, an acute life-threatening inflammation of the bowel. [23] Additionally, some people may develop palmar plantar erythrodysesthesia (PPE), characterized by skin eruptions on the palms of the hand or soles of the feet, swelling, pain, and erythema. [18] Due to these side effects and its red color, doxorubicin has earned the nickname "red devil" [24] [25] or "red death." [26]
Chemotherapy can cause reactivation of hepatitis B, and doxorubicin-containing regimens are no exception. [27] [28]
Doxorubicin and several chemotherapeutic drugs (including cyclophosphamide) can cause a loss of skin pigmentation. [29]
There is a pegylated (polyethylene glycol coated) liposome-encapsulated form of doxorubicin, developed to treat Kaposi's sarcoma. The polyethylene glycol coating results in preferential concentration of doxorubicin in the skin. However, this also results in a side effect called palmar plantar erythrodysesthesia (PPE), more commonly known as hand-foot syndrome.
Following administration of this form of doxorubicin, small amounts of the drug can leak from capillaries in the palms of the hands and soles of the feet. The result of this leakage is redness, tenderness, and peeling of the skin that can be uncomfortable and even painful. In clinical testing at 50 mg/m2 dosing every four weeks, half of people developed hand-foot syndrome. The rate of this side effect limits the dose of this formulation that can be given as compared with plain doxorubicin in the same treatment regimen, thereby limiting potential substitution. Substitution would be desirable because liposome-encapsulated doxorubicin is less cardiotoxic than unencapsulated doxorubicin. This liposome-encapsulated form is also approved by the FDA for treatment of ovarian cancer and multiple myeloma. [30] [31]
A non-pegylated liposomal doxorubicin, called Myocet, is approved in the European Union and in Canada for the treatment of metastatic breast cancer in combination with cyclophosphamide, [2] but it has not been approved by the FDA for use in the United States. Unlike Doxil, the Myocet liposome does not have a polyethylene glycol coating, and therefore does not result in the same rate of PPE. The minimization of this side effect may allow for one-for-one (1:1) substitution with doxorubicin in the same treatment regimen, thereby improving safety with no loss of efficacy. Like Doxil, the liposomal encapsulation of the doxorubicin limits the cardiotoxicity. In theory, by limiting the cardiotoxicity of doxorubicin through liposomal encapsulation, it can be used safely in concurrent combination with other cardiotoxic chemotherapy drugs, such as trastuzumab. There is an FDA black box warning that trastuzumab cannot be used in concurrent combination with doxorubicin, only in sequential combination. Though concurrent combination of trastuzumab and doxorubicin in clinical studies found superior tumor response, the combination resulted in unacceptable cardiotoxicity, including risk of cardiac failure manifesting as congestive heart failure (CHF). Published phase II study results have shown that Myocet, trastuzumab, and paclitaxel can safely be used concurrently without the cardiac risk, as measured by reduction in LVEF function, while still achieving superior tumor response. This finding is the basis for the ongoing phase III trial for FDA approval. [30]
Doxorubicin (DXR) is a 14-hydroxylated version of daunorubicin, the immediate precursor of DXR in its biosynthetic pathway.
Daunorubicin is more abundantly found as a natural product because it is produced by a number of different wild type strains of Streptomyces . In contrast, only one known non-wild type species, Streptomyces peucetius subspecies cesius ATCC 27952, was initially found to be capable of producing the more widely used doxorubicin. [32] This strain was created by Arcamone et al. in 1969 by mutating a strain producing daunorubicin, but not DXR, at least in detectable quantities. [33] Subsequently, Hutchinson's group showed that under special environmental conditions, or by the introduction of genetic modifications, other strains of Streptomyces can produce doxorubicin. [34] His group also cloned many of the genes required for DXR production, although not all of them have been fully characterized. In 1996, Strohl's group discovered, isolated and characterized dox A, the gene encoding the enzyme that converts daunorubicin into DXR. [35]
By 1999, they produced recombinant dox A, a cytochrome P450 oxidase, and found that it catalyzes multiple steps in DXR biosynthesis, including steps leading to daunorubicin. [36] This was significant because it became clear that all daunorubicin-producing strains have the necessary genes to produce DXR, the much more therapeutically important of the two. Hutchinson's group went on to develop methods to improve the yield of DXR, from the fermentation process used in its commercial production, not only by introducing dox A encoding plasmids, but also by introducing mutations to deactivate enzymes that shunt DXR precursors to less useful products, for example baumycin-like glycosides. [32] Some triple mutants, that also over-expressed dox A, were able to double the yield of DXR. This is of more than academic interest, because at that time DXR cost about $1.37 million per kg and current production in 1999 was 225 kg per annum. [37]
More efficient production techniques have brought the price down to $1.1 million per kg for the nonliposomal formulation. Although DXR can be produced semi-synthetically from daunorubicin, the process involves electrophilic bromination and multiple steps, and the yield is poor. [38] Since daunorubicin is produced by fermentation, it would be ideal if the bacteria could complete DXR synthesis more effectively.
Doxorubicin interacts with DNA by intercalation and inhibition of macromolecular biosynthesis. [11] [40] [41] This inhibits the progression of topoisomerase II, an enzyme which relaxes supercoils in DNA for transcription. [42] Doxorubicin stabilizes the topoisomerase II complex after it has broken the DNA chain for replication, preventing the DNA double helix from being released and thereby stopping the process of replication. [11] It may also increase quinone type free radical production, hence contributing to its cytotoxicity. [15]
The planar aromatic chromophore portion of the molecule intercalates between two base pairs of the DNA, while the six-membered daunosamine sugar sits in the minor groove and interacts with flanking base pairs immediately adjacent to the intercalation site, as evidenced by several crystal structures. [39] [43]
By intercalation, doxorubicin can also induce histone eviction from transcriptionally active chromatin. [44] [45] As a result, the DNA damage response, epigenome and transcriptome are deregulated in doxorubicin-exposed cells. [44]
In the 1950s, an Italian research company, Farmitalia Research Laboratories, began an organized effort to find anticancer compounds from soil-based microbes. A soil sample was isolated from the area surrounding the Castel del Monte, a 13th-century castle. A new strain of Streptomyces peucetius , which produced a red pigment, was isolated, and an antibiotic from this bacterium was effective against tumors in mice. Since a group of French researchers discovered the same compound at about the same time, the two teams named the compound daunorubicin, combining the name Dauni , a pre-Roman tribe that occupied the area of Italy where the compound was isolated, with the French word for ruby, rubis, describing the color. [46] [47] [48] Clinical trials began in the 1960s, and the drug was successful in treating acute leukemia and lymphoma. However, by 1967, it was recognized that daunorubicin could lead to fatal cardiac toxicity. [49]
Researchers at Farmitalia soon discovered that changes in biological activity could be made by minor changes in the structure of the compound. A strain of Streptomyces was mutated using N-nitroso-N-methyl urethane, and this new strain produced a different, red-colored antibiotic. They named this new compound Adriamycin, after the Adriatic Sea, and the name was later changed to doxorubicin to conform to the established naming convention. [33] Doxorubicin showed better activity than daunorubicin against mouse tumors, and especially solid tumors. It also showed a higher therapeutic index, yet the cardiotoxicity remained. [50]
Doxorubicin and daunorubicin together can be thought of as prototype compounds for the anthracyclines. Subsequent research has led to many other anthracycline antibiotics, or analogs, and there are now over 2,000 known analogs of doxorubicin. By 1991, 553 of them had been evaluated in the screening program at the National Cancer Institute (NCI). [46] In 2016 GPX-150 was granted orphan drug designation by US FDA. [51]
On 24 March 2022, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Zolsketil pegylated liposomal, intended for the treatment of metastatic breast cancer, advanced ovarian cancer, progressive multiple myeloma and AIDS-related Kaposi's sarcoma. [52] The applicant for this medicinal product is Accord Healthcare S.L.U. [52] Zolsketil pegylated liposomal is a hybrid medicine of Adriamycin. [52] It contains the same active substance as Adriamycin, but is available in a pegylated liposomal formulation. [52] Zolsketil pegylated liposomal was approved for medical use in the European Union in May 2022. [3] [53]
On 21 July 2022, the CHMP adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Celdoxome pegylated liposomal, intended for the treatment of metastatic breast cancer, advanced ovarian cancer, progressive multiple myeloma and AIDS-related Kaposi's sarcoma. [54] The applicant for this medicinal product is YES Pharmaceutical Development Services GmbH. [54] Celdoxome pegylated liposomal is a hybrid medicine of Adriamycin which has been authorized in the EU since 24 October 1979. [54] Celdoxome pegylated liposomal contains the same active substance as Adriamycin, but is available in a pegylated liposomal formulation. [54] Celdoxome pegylated liposomal was approved for medical use in the European Union in September 2022. [4]
It is also known as hydroxydaunorubicin and hydroxydaunomycin. [55]
It is sold under a number of different brand names, including Adriamycin PFS, Adriamycin RDF, or Rubex. [9]
Doxorubicin is photosensitive, and containers are often covered by an aluminum bag and/or brown wax paper to prevent light from affecting it. [9] Doxorubicin is also available in liposome-encapsulated forms as Doxil (pegylated form), Myocet (nonpegylated form), and Caelyx, [1] which are also given by intravenous injection. [9]
The FDA approved the first generic version of Doxil, made by Sun, in February 2013. [56]
Combination therapy experiments with sirolimus (rapamycin) and doxorubicin have shown promise in treating Akt-positive lymphomas in mice. [57]
Further, the release of photo-activated adriamycin with the aid of nanoporous optical antenna resulted in significant anti-cancer effect in MCF-7 breast cancer cells. [58] In 2006, animal research coupling a murine monoclonal antibody with doxorubicin created an immunoconjugate that was able to eliminate HIV-1 infection in mice. [59] [60]
There is some evidence for antimalarial activity for doxorubicin and similar compounds. In 2009, a compound similar in structure to doxorubicin was found to inhibit plasmepsin II, an enzyme unique to the malarial parasite Plasmodium falciparum . [61] The pharmaceutical company GlaxoSmithKline (GSK) later identified doxorubicin in a set of compounds that inhibit parasite growth. [62]
Doxorubicin is also known to be fluorescent. This has often been used to characterize doxorubicin concentrations, and has opened the possibility of using the molecule as a theranostic agent. However, there are significant limitations, as doxorubicin's fluorescence spectrum is known to depend on a variety of factors, including the pH of the environment, solvent dielectric constant and others. Doxorubicin fluorescence is quenched by binding to DNA, and shielded by micelle encapsulation. It is also known to self-quench at high concentrations. In contrast, histone binding amplifies fluorescence. [63] [64]
An antimetabolite is a chemical that inhibits the use of a metabolite, which is another chemical that is part of normal metabolism. Such substances are often similar in structure to the metabolite that they interfere with, such as the antifolates that interfere with the use of folic acid; thus, competitive inhibition can occur, and the presence of antimetabolites can have toxic effects on cells, such as halting cell growth and cell division, so these compounds are used in chemotherapy for cancer.
Daunorubicin, also known as daunomycin, is a chemotherapy medication used to treat cancer. Specifically it is used for acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myelogenous leukemia (CML), and Kaposi's sarcoma. It is administered by injection into a vein. A liposomal formulation known as liposomal daunorubicin also exists.
Anthracyclines are a class of drugs used in cancer chemotherapy that are extracted from Streptomyces peucetius bacterium. These compounds are used to treat many cancers, including leukemias, lymphomas, breast, stomach, uterine, ovarian, bladder cancer, and lung cancers. The first anthracycline discovered was daunorubicin, which is produced naturally by Streptomyces peucetius, a species of Actinomycetota. Clinically the most important anthracyclines are doxorubicin, daunorubicin, epirubicin and idarubicin.
Epirubicin is an anthracycline drug used for chemotherapy. It can be used in combination with other medications to treat breast cancer in patients who have had surgery to remove the tumor. It is marketed by Pfizer under the trade name Ellence in the US and Pharmorubicin or Epirubicin Ebewe elsewhere.
CHOP is the acronym for a chemotherapy regimen used in the treatment of non-Hodgkin lymphoma. CHOP consists of:
Cardiotoxicity is the occurrence of heart dysfunction as electric or muscle damage, resulting in heart toxicity. This can cause heart failure, arrhythmia, myocarditis, and cardiomyopathy in patients. Some effects are reversible, while in others, permanent damage requiring further treatment may arise. The heart becomes weaker and is not as efficient in pumping blood. Cardiotoxicity may be caused by chemotherapy treatment and/or radiotherapy; complications from anorexia nervosa; adverse effects of heavy metals intake; the long-term abuse of or ingestion at high doses of certain strong stimulants such as cocaine; or an incorrectly administered drug such as bupivacaine.
Primary effusion lymphoma (PEL) is classified as a diffuse large B cell lymphoma. It is a rare malignancy of plasmablastic cells that occurs in individuals that are infected with the Kaposi's sarcoma-associated herpesvirus. Plasmablasts are immature plasma cells, i.e. lymphocytes of the B-cell type that have differentiated into plasmablasts but because of their malignant nature do not differentiate into mature plasma cells but rather proliferate excessively and thereby cause life-threatening disease. In PEL, the proliferating plasmablastoid cells commonly accumulate within body cavities to produce effusions, primarily in the pleural, pericardial, or peritoneal cavities, without forming a contiguous tumor mass. In rare cases of these cavitary forms of PEL, the effusions develop in joints, the epidural space surrounding the brain and spinal cord, and underneath the capsule which forms around breast implants. Less frequently, individuals present with extracavitary primary effusion lymphomas, i.e., solid tumor masses not accompanied by effusions. The extracavitary tumors may develop in lymph nodes, bone, bone marrow, the gastrointestinal tract, skin, spleen, liver, lungs, central nervous system, testes, paranasal sinuses, muscle, and, rarely, inside the vasculature and sinuses of lymph nodes. As their disease progresses, however, individuals with the classical effusion-form of PEL may develop extracavitary tumors and individuals with extracavitary PEL may develop cavitary effusions.
Trabectedin, sold under the brand name Yondelis, is an antitumor chemotherapy medication for the treatment of advanced soft-tissue sarcoma and ovarian cancer.
Breast cancer chemotherapy refers to the use of cytotoxic drugs (chemotherapy) in the treatment of breast cancer.
Doxorubicin (DXR) is a 14-hydroxylated version of daunorubicin, the immediate precursor of DXR in its biosynthetic pathway. Daunorubicin is more abundantly found as a natural product because it is produced by a number of different wild type strains of Streptomyces. In contrast, only one known non-wild type species, Streptomyces peucetius subspecies caesius ATCC 27952, was initially found to be capable of producing the more widely used doxorubicin. This strain was created by Arcamone et al. in 1969 by mutating a strain producing daunorubicin, but not DXR, at least in detectable quantities. Subsequently, Hutchinson's group showed that under special environmental conditions, or by the introduction of genetic modifications, other strains of streptomyces can produce doxorubicin. His group has also cloned many of the genes required for DXR production, although not all of them have been fully characterized. In 1996, Strohl's group discovered, isolated and characterized dox A, the gene encoding the enzyme that converts daunorubicin into DXR. By 1999, they produced recombinant Dox A, a Cytochrome P450 oxidase, and found that it catalyzes multiple steps in DXR biosynthesis, including steps leading to daunorubicin. This was significant because it became clear that all daunorubicin producing strains have the necessary genes to produce DXR, the much more therapeutically important of the two. Hutchinson's group went on to develop methods to improve the yield of DXR, from the fermentation process used in its commercial production, not only by introducing Dox A encoding plasmids, but also by introducing mutations to deactivate enzymes that shunt DXR precursors to less useful products, for example baumycin-like glycosides. Some triple mutants, that also over-expressed Dox A, were able to double the yield of DXR. This is of more than academic interest because at that time DXR cost about $1.37 million per kg and current production in 1999 was 225 kg per annum. More efficient production techniques have brought the price down to $1.1 million per kg for the non-liposomal formulation. Although DXR can be produced semi-synthetically from daunorubicin, the process involves electrophilic bromination and multiple steps and the yield is poor. Since daunorubicin is produced by fermentation, it would be ideal if the bacteria could complete DXR synthesis more effectively.
Pixantrone is an experimental antineoplastic (anti-cancer) drug, an analogue of mitoxantrone with fewer toxic effects on cardiac tissue. It acts as a topoisomerase II poison and intercalating agent. The code name BBR 2778 refers to pixantrone dimaleate, the actual substance commonly used in clinical trials.
Kaposi's sarcoma (KS) is a type of cancer that can form masses on the skin, in lymph nodes, in the mouth, or in other organs. The skin lesions are usually painless, purple and may be flat or raised. Lesions can occur singly, multiply in a limited area, or may be widespread. Depending on the sub-type of disease and level of immune suppression, KS may worsen either gradually or quickly. Except for Classical KS where there is generally no immune suppression, KS is caused by a combination of immune suppression and infection by Human herpesvirus 8.
OSI-7904 is a noncompetitive liposomal thymidylate synthase inhibitor. OSI-7904 is a benzoquinazoline folate analog with antineoplastic activity. As a thymidylate synthase inhibitor, OSI-7904 noncompetitively binds to thymidylate synthase, resulting in inhibition of thymine nucleotide synthesis and DNA replication.
Follicular dendritic cell sarcoma (FDCS) is an extremely rare neoplasm. While the existence of FDC tumors was predicted by Lennert in 1978, the tumor wasn't fully recognized as its own cancer until 1986 after characterization by Monda et al. It accounts for only 0.4% of soft tissue sarcomas, but has significant recurrent and metastatic potential and is considered an intermediate grade malignancy. The major hurdle in treating FDCS has been misdiagnosis. It is a newly characterized cancer, and because of its similarities in presentation and markers to lymphoma, both Hodgkin and Non-Hodgkin subtypes, diagnosis of FDCS can be difficult. With recent advancements in cancer biology better diagnostic assays and chemotherapeutic agents have been made to more accurately diagnose and treat FDCS.
Microbubbles are bubbles smaller than one hundredth of a millimetre in diameter, but larger than one micrometre. They have widespread application in industry, medicine, life science, and food technology. The composition of the bubble shell and filling material determine important design features such as buoyancy, crush strength, thermal conductivity, and acoustic properties.
Streptomyces peucetius is a bacterium species in the genus Streptomyces.
This is a historical timeline of the development and progress of cancer treatments, which includes time of discovery, progress, and approval of the treatments.
Bradley J. Monk is an American gynecologic oncologist, academician and researcher. He is a professor on the Clinical Scholar Track in the Department of Obstetrics and Gynecology at the University of Arizona College of Medicine in Phoenix, Arizona, as well as at the Creighton University School of Medicine in Omaha, Nebraska. He also serves as Director of the Division of Gynecologic Oncology at the St. Joseph's Hospital and Medical Center in Phoenix.
pH-responsive tumor-targeted drug delivery is a specialized form of targeted drug delivery that utilizes nanoparticles to deliver therapeutic drugs directly to cancerous tumor tissue while minimizing its interaction with healthy tissue. Scientists have used drug delivery as a way to modify the pharmacokinetics and targeted action of a drug by combining it with various excipients, drug carriers, and medical devices. These drug delivery systems have been created to react to the pH environment of diseased or cancerous tissues, triggering structural and chemical changes within the drug delivery system. This form of targeted drug delivery is to localize drug delivery, prolongs the drug's effect, and protect the drug from being broken down or eliminated by the body before it reaches the tumor.
Immunoliposome therapy is a targeted drug delivery method that involves the use of liposomes coupled with monoclonal antibodies to deliver therapeutic agents to specific sites or tissues in the body. The antibody modified liposomes target tissue through cell-specific antibodies with the release of drugs contained within the assimilated liposomes. Immunoliposome aims to improve drug stability, personalize treatments, and increased drug efficacy. This form of therapy has been used to target specific cells, protecting the encapsulated drugs from degradation in order to enhance their stability, to facilitate sustained drug release and hence to advance current traditional cancer treatment.