What is Kaposi sarcoma

Kaposi sarcoma is a cancer that develops from the cells that line the blood vessels and the lymphatic system. Kaposi sarcoma usually appears as tumors on the skin or on mucosal surfaces such as inside the mouth, but these tumors can also develop in other parts of the body, such as in the lymph nodes (bean-sized collections of immune cells throughout the body), the lungs, or digestive tract. Kaposi sarcoma was considered very rare prior to the AIDS epidemic. AIDS is due to infection with human immunodeficiency virus (HIV).

The cancer cells of Kaposi sarcoma form purple, red, or brown blotches or tumors on the skin. These affected areas are called lesions. The skin lesions of Kaposi sarcoma most often show on the legs or face. They may look bad, but they usually cause no symptoms. Some lesions on the legs or in the groin area may cause the legs and feet to swell painfully.

Kaposi sarcoma can cause serious problems or even become life threatening when the lesions are in the lungs, liver, or digestive tract. Kaposi sarcoma in the digestive tract, for example, can cause bleeding, while tumors in the lungs may cause trouble breathing.

Kaposi sarcoma is caused by infection with human herpesvirus-8 (HHV-8). Most people infected with HHV-8 don’t get Kaposi sarcoma. It usually happens in:

• People with weak immune systems, due to HIV/AIDS, drugs taken after an organ transplant, or another disease
• Older men of Jewish or Mediterranean descent
• Young men in Africa

Kaposi sarcoma skin lesions may not cause symptoms. But they can spread to other parts of the body, especially in people with HIV/AIDS. If they spread to the digestive tract or lungs, they can cause bleeding. Lesions on the lungs can also make it hard to breathe.

There are four types of Kaposi sarcoma:

1. HIV-AIDS associated Kaposi sarcoma (also known as epidemic Kaposi sarcom) — mainly affects men who have sex with men. The is the most common type of Kaposi sarcoma in the United States or AIDS-associated Kaposi sarcoma. This type of Kaposi sarcoma develops in people who are infected with HIV, the virus that causes AIDS. It is also one of the most common forms of cancer, especially in children, in Uganda and Zambia.
2. Classic (Mediterranean) Kaposi sarcoma — affects elderly men of Mediterranean and Middle European descent and in men in Sub-Saharan Africa. Associated with a higher rate of diabetes mellitus, but not associated with HIV (human immunodeficiency virus) infection. Classic Kaposi sarcoma is more common in men than in women. People typically have one or more lesions on the legs, ankles, or the soles of their feet. Compared to other types of Kaposi sarcoma, the lesions in this type do not grow as quickly, and new lesions do not develop as often. The immune system of people with classic Kaposi sarcoma is not as weak as it is in those who have epidemic Kaposi sarcoma, but it may be weaker than normal. Getting older can naturally weaken the immune system a little. When this occurs, people who already have a Kaposi sarcoma–associated herpesvirus (human herpesvirus-8) infection are more likely to develop Kaposi sarcoma.
3. Endemic or African Kaposi sarcoma — arises in some parts of Africa in children and young adults. Endemic Kaposi sarcoma occurs in people living in Equatorial Africa and is sometimes called African Kaposi sarcoma. Kaposi sarcoma–associated herpesvirus (human herpesvirus-8) infection is much more common in Africa than in other parts of the world, so the risk of Kaposi sarcoma is higher. Other factors in Africa that weaken the immune system (such as malaria, other chronic infections, and malnutrition) also probably contribute to the development of Kaposi sarcoma, since the disease affects a broader group of people that includes children and women. Endemic Kaposi sarcoma tends to occur in younger people (usually under age 40). Rarely a more aggressive form of endemic Kaposi sarcoma is seen in children before puberty. This type usually affects lymph nodes and other organs and can progress quickly. Endemic Kaposi sarcoma used to be the most common type of Kaposi sarcoma in Africa. Then, as AIDS became more common in Africa, the epidemic type became more common.
4. Iatrogenic (transplant-related) Kaposi sarcoma — as a result of drug treatment causing immune suppression. When Kaposi sarcoma develops in people whose immune systems have been suppressed after an organ transplant, it is called iatrogenic, or transplant-related Kaposi sarcoma. Most transplant patients need to take drugs to keep their immune system from rejecting (attacking) the new organ. But by weakening the body’s immune system, these drugs increase the chance that someone infected with Kaposi sarcoma–associated herpesvirus (human herpesvirus-8) will develop Kaposi sarcoma. Stopping the immune-suppressing drugs or lowering their dose often makes Kaposi sarcoma lesions go away or get smaller.

In the United States, Kaposi sarcoma was particularly common in the 1980s, especially amongst HIV-positive men who had sex with men, in which it has a very aggressive course. A person infected with HIV (someone who is HIV-positive) does not necessarily have AIDS, but the virus can be present in the body for a long time, often many years, before causing major illness. The disease known as AIDS begins when the virus has seriously damaged a person’s immune system, which means they can get certain types of infections (such as Kaposi sarcoma–associated herpesvirus or human herpesvirus-8) or other medical complications, including Kaposi sarcoma.

Kaposi sarcoma is considered an AIDS defining illness. This means that when Kaposi sarcoma occurs in someone infected with HIV, that person officially has AIDS (and is not just HIV-positive).

Kaposi sarcoma occurs less frequently in intravenous drug users and is rare in women, hemophiliacs or their sexual partners. HIV–associated Kaposi sarcoma is more common in women in some parts of Africa.

In the United States, treating HIV infection with highly active antiretroviral therapy (HAART) has resulted in fewer cases of AIDS-associated Kaposi sarcoma. Still, some patients can develop Kaposi sarcoma in the first few months of HAART treatment.

For most patients with HIV, highly active antiretroviral therapy (HAART) can often keep advanced Kaposi sarcoma from developing. Still, Kaposi sarcoma can occur in people whose HIV is well controlled with HAART. Even if Kaposi sarcoma develops, it is still important to continue HAART.

In areas of the world where it is not easy to get HAART, Kaposi sarcoma in AIDS patients can advance quickly.

Iatrogenic Kaposi sarcoma is a particular concern for organ transplant patients, especially in geographic areas associated with high levels of infection with Kaposi sarcoma herpes virus (KSHV). Most have the virus prior to transplantation, but the drugs causes it to reactivate. Use of corticosteroids and biologics like rituximab, infliximab, and abatacept, prescribed for chronic inflammatory and autoimmune conditions, are also prone to develop Kaposi sarcoma.

There have been various attempts to classify Kaposi sarcoma, depending on whether it is localized or disseminated in the skin, and if there is lymph node or internal organ involvement. The degree of immunosuppression present may also be used in staging systems.

Kaposi sarcoma has a variable course. Some patients develop only a few minor skin lesions whilst others have much more extensive external and internal disease. The latter lesions may result in fatal complications, e.g., from bleeding, obstruction or perforation of an organ. Kaposi sarcoma is not curable, but it can be treated and its symptoms controlled.

Treatment depends on where the Kaposi sarcoma lesions are and how bad they are. Options include radiation therapy, surgery, chemotherapy, and biologic therapy. People with HIV/AIDS also take HIV/AIDS Medicines.

In HIV disease, if the lesions are not widespread or troublesome, often the best approach is simply to treat the underlying HIV infection with highly active antiretroviral drug combinations that suppress HIV replication (HAART).

• Highly active antiretroviral therapy (HAART) drugs reduce the frequency of Kaposi sarcoma and may also prevent its progression or the development of new lesions.
• The improvement in immune function is thought to result in reduced levels of tumour growth-promoting proteins.
• Highly active antiretroviral therapy (HAART) plus chemotherapy is found to be more effective than HAART alone or of chemotherapy alone in treating Kaposi sarcoma.

Iatrogenic Kaposi sarcoma may improve or clear if it is possible to stop immune suppressive medication.

The choice of more specific treatment depends largely on the extent of the disease.

What does Kaposi sarcoma look like

Figure 1. Kaposi sarcoma [Classic (Mediterranean) Kaposi sarcoma]

Figure 2. Kaposi sarcoma mouth (HIV associated)

Figure 3. Oral kaposi sarcoma (HIV associated)

Figure 4. Kaposi sarcoma hands (nodules)

Kaposi sarcoma symptoms

Kaposi sarcoma presents as red to purplish macules (spots that are flat and not raised above the surrounding skin), papules (flat but slightly raised) and nodules (bumps) anywhere on the skin or mucous membranes lining the mouth, nose, and throat; lymph nodes; or other organs. Initially, the lesions are small and painless but they can ulcerate and become painful.

There are various forms of Kaposi sarcoma:

• Localized nodular Kaposi sarcoma
• Locally aggressive Kaposi sarcoma
• Generalized lymphadenopathic Kaposi sarcoma
• Patch stage Kaposi sarcoma
• Localised plaques of Kaposi sarcoma
• Exophytic Kaposi sarcoma
• Infiltrative plaques of Kaposi sarcoma
• Disseminated cutaneous and visceral Kaposi sarcoma
• Telangiectatic Kaposi sarcoma
• Keloidal Kaposi sarcoma
• Ecchymotic Kaposi sarcoma
• Lymphangioma-like/cavernous Kaposi sarcoma.

Kaposi sarcoma often starts as flat patches on one or both lower legs, often in association with lymphedema. The patches evolve into plaques, nodule or scaly tumors.

Kaposi sarcoma in association with HIV infection may develop at any time during the course of illness. Generally, the greater the immunosuppression (e.g. with CD4 cell counts less than 200/mm³) the more extensive and aggressive the Kaposi sarcoma will be.

Kaposi sarcoma lesions can also occur internally; in the gut, lungs, genitals, lymphatic system and elsewhere. These internal lesions may cause symptoms such as:

• Discomfort with swallowing
• Bleeding
• Hematemesis (vomiting blood)
• Hematochezia (passage of fresh blood through the anus)
• Melena
• Bowel obstruction
• Shortness of breath
• Swollen legs.

Lesions in the lungs might block part of an airway and cause shortness of breath. Lesions that develop in the stomach and intestines can cause abdominal pain and diarrhea.

Sometimes Kaposi sarcoma lesions bleed. If the lesions are in the lung, it can cause you to cough up blood and lead to shortness of breath. If the lesions are in the stomach or intestines, it can cause bowel movements to become black and tarry or bloody. Bleeding from lesions in the stomach and intestines can be so slow that blood isn’t visible in the stool, but over time the blood loss can lead to low red blood cell counts (anemia). This can cause symptoms like tiredness and shortness of breath.

Kaposi sarcoma causes

Kaposi sarcoma is caused by infection with a virus called the Kaposi sarcoma–associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV8). Kaposi sarcoma–associated herpesvirus (KSHV) is in the same family as Epstein-Barr virus (EBV), the virus that causes infectious mononucleosis (mono) and is linked to several types of cancer.

In Kaposi sarcoma, the cells that line blood and lymphatic vessels (called endothelial cells) are infected with Kaposi sarcoma–associated herpesvirus (human herpesvirus 8). The virus brings genes into the cells that can cause the cells to divide too much and to live longer than they should. These same genes may cause the endothelial cells to form new blood vessels and may also increase the production of certain chemicals that cause inflammation. These types of changes may eventually turn them into cancer cells.

Kaposi sarcoma–associated herpesvirus (human herpesvirus 8) infection is much more common than Kaposi sarcoma. Most people infected with this virus do not get Kaposi sarcoma and many will never show any symptoms. Infection with Kaposi sarcoma–associated herpesvirus (human herpesvirus 8) is needed to cause Kaposi sarcoma, but in most cases infection with Kaposi sarcoma–associated herpesvirus (human herpesvirus 8) alone does not lead to Kaposi sarcoma. Most people who develop Kaposi sarcoma have the Kaposi sarcoma–associated herpesvirus (human herpesvirus 8) and also have a weakened immune system, due to HIV infection, organ transplant, being older, or some other factor.

Kaposi sarcoma–associated herpesvirus (human herpesvirus 8) may lie dormant, or replicate and cause disease. Kaposi sarcoma may cause of some forms of non-Hodgkin lymphoma and Castleman disease.

The number of people infected with Kaposi sarcoma–associated herpesvirus (human herpesvirus 8) varies in different places around the world. In the United States, studies have found that less than 10% of people are infected with Kaposi sarcoma–associated herpesvirus (human herpesvirus 8). The infection is more common in people infected with HIV than in the general population in the United States. Kaposi sarcoma–associated herpesvirus (human herpesvirus 8) infection is also more common in men who have sex with men than in men who only have sex with women.

In some areas of Africa, up to 80% of the population shows signs of Kaposi sarcoma–associated herpesvirus (human herpesvirus 8) infection. In these areas the virus seems to spread from mother to child. Kaposi sarcoma–associated herpesvirus (human herpesvirus 8) is also found in saliva, semen, and vaginal fluid, which may be some ways it is passed to others.

Kaposi sarcoma prevention

Kaposi sarcoma is caused by the Kaposi sarcoma–associated herpesvirus (human herpesvirus 8). There are no vaccines at this time to protect people against Kaposi sarcoma–associated herpesvirus (human herpesvirus 8). For now, preventing Kaposi sarcoma depends on reducing the chance of becoming infected with Kaposi sarcoma–associated herpesvirus (human herpesvirus 8) and reducing the chance that people who are infected with Kaposi sarcoma–associated herpesvirus will develop Kaposi sarcoma.

Most cases of Kaposi sarcoma in the United States occur in people with HIV and AIDS. Taking measures to avoid becoming infected with HIV could prevent most cases of Kaposi sarcoma in this country.

• Since HIV can be spread through sex, avoiding unprotected sex with people infected with HIV could help prevent these infections. Many people with HIV don’t know that they are infected, so many public health workers recommend using a condom during any sexual contact.
• Another way to lower the risk of getting HIV is to take a pill every day that contains ant-viral drugs. This is called pre-exposure prophylaxis (PrEP). At this time, the Centers for Disease Control and Prevention (CDC) recommends PrEP for people who are HIV negative and at very high risk for HIV. The CDC has more information about who should use PrEP.
• HIV can also be spread through the use of contaminated (dirty) needles to inject recreational drugs. For people who inject drugs, the safest way to avoid HIV is to quit. However, some people are unable to quit on their own or get help in quitting, and they may not be able to stop using drugs right away. For these people, clean needles and injection supplies can help protect them. In some areas, there are programs to make sure that drug users can get clean needles and syringes.
• HIV-infected mothers can pass the virus to their babies during pregnancy, delivery, or breastfeeding. Treating the mothers and infants with anti-HIV drugs and avoiding breastfeeding can greatly reduce the risk of these infections.
• In the past, blood product transfusions and organ transplants were responsible for some HIV infections. As a result of improved testing for HIV, there is now a very low risk of HIV infection from blood products or organ transplants in the United States.

For people who are infected with HIV and Kaposi sarcoma–associated herpesvirus, taking the right medicines can reduce the chance of developing Kaposi sarcoma.

• Testing for HIV can identify people infected with this virus. People with HIV should get treatment to help strengthen their immune system, which usually includes highly active antiretroviral therapy (HAART). HAART reduces the risk that people with HIV will develop Kaposi sarcoma (and AIDS). Treating infections that commonly occur in people with weakened immunity also reduces the likelihood of developing problems with Kaposi sarcoma.
• HIV-infected people who take drugs to treat herpesvirus infections (such as ganciclovir or foscarnet) are less likely to develop Kaposi sarcoma because these drugs also work against Kaposi sarcomaHV (which is a type of herpesvirus). Still, these drugs can have serious side effects, so they are only taken to treat certain viral infections, not to prevent Kaposi sarcoma.

For people who are at risk of developing Kaposi sarcoma after an organ transplant (iatrogenic Kaposi sarcoma), using certain types of immune suppressive drugs, such as sirolimus or everolimus (mTOR inhibitors), may reduce the chances of Kaposi sarcoma while still helping prevent rejection of the new organ.

How is Kaposi sarcoma diagnosed?

Blood tests may show no abnormality, depending whether there are associated disorders such as AIDS. Anemia may arise if there is bleeding. Kaposi sarcoma herpes virus assays or antibody titers to Kaposi sarcoma herpes virus are difficult to interpret. CD4 lymphocyte counts and plasma HIV load studies are performed in patients with HIV infection.

The appearance of Kaposi sarcoma lesions is often typical but a skin biopsy of a lesion allows a definite diagnosis, as various lesions such as melanoma, fungal infections, and mycetoma mimic Kaposi sarcoma in appearance and location. Histopathology shows red cells in slit-like spaces formed by atypical spindle cell proliferation of endothelial cells and associated with inflammatory cells.

Chest x-ray

Your lungs may be x-rayed to see if Kaposi sarcoma is there. If the x-ray shows something abnormal, other tests, such as a CT scan, might be needed to tell for sure if it is Kaposi sarcoma or some other condition.

For people known to have Kaposi sarcoma in the lung, chest x-rays can be used to see how the disease is responding to treatment.

Bronchoscopy

Bronchoscopy is a test that lets the doctor look into the windpipe (trachea) and the large airways of the lungs. This procedure is often done if you are having problems such as shortness of breath or coughing up blood, or if the chest x-ray or CT scan shows something abnormal. Any of these could mean that Kaposi sarcoma is in the lungs.

Before bronchoscopy starts, you are put to sleep with a light anesthesia. Then the doctor inserts the bronchoscope (a thin, flexible lighted tube with a small video camera on the end) through the mouth, down the windpipe, and into the lungs. If the doctor sees an abnormal area that might be Kaposi sarcoma, it can be biopsied through the bronchoscope. Bronchoscopy with biopsies can also be used to help diagnose other lung problems seen in AIDS patients, such as pneumonia.

Gastrointestinal endoscopy

One or more of these tests might be done when the doctor suspects that Kaposi sarcoma is in the stomach or intestines and is causing problems.

Upper endoscopy (also called esophagogastroduodenoscopy)

Upper endoscopy is used to look at the inner lining of the esophagus, the stomach, and the first part of the small intestine. For this procedure, you are first given drugs to make you sleepy. Then, the doctor guides the endoscope (a thin, flexible, lighted tube with a small video camera on the end) through the mouth and esophagus and into the stomach and small intestine. This lets the doctor see things like ulcers, infections, and Kaposi sarcoma lesions.

If an abnormal area is seen, the doctor can use small surgical instruments through the endoscope to biopsy it.

Colonoscopy

Colonoscopy is used to look inside the large intestine (colon and rectum). Before this test can be done, the colon and rectum must be cleaned out to remove any stool. This often means drinking a large amount of a liquid laxative the night before and the morning of the procedure, and spending a lot of time in the bathroom.

Just before the procedure, you will be given intravenous (IV) medicine to make you relaxed or even asleep (sedation). Then a colonoscope (a long, flexible, tube with a light and video camera on the end) is inserted through the rectum and into the colon. Any abnormal areas seen can be biopsied.

Capsule endoscopy

Capsule endoscopy is a way to look at the small intestine. It is not truly a type of endoscopy, since it doesn’t use an endoscope. Instead, you swallow a capsule (about the size of a large vitamin pill) that contains a light source and a very small camera. Like any other pill, the capsule goes through the stomach and into the small intestine.

As it travels through the small intestine (usually over about 8 hours), it takes thousands of pictures. These images are transmitted electronically to a device worn around your waist while you go on with normal daily activities. The images can then be downloaded onto a computer, where the doctor can look at them as a video.

The capsule passes out of the body through the stool during a normal bowel movement and is discarded. A disadvantage of this test is that it doesn’t allow the doctor to biopsy any abnormal areas. You will probably be told not to eat or drink for about 12 hours before the test.

Double balloon enteroscopy

Double balloon enteroscopy is another way to look at the small intestine. Regular endoscopy cannot look very far into the small intestine because it is too long and has too many curves. This method gets around these problems by using a special endoscope that is made up of 2 tubes, one inside the other. For this test, you are given intravenous (IV) medicine to make you relaxed (sedation), and may be even given general anesthesia (so that you are asleep).

The endoscope is then inserted either through the mouth or the anus, depending on if there is a specific part of the small intestine to be examined. Once inside the small intestine, the inner tube, which has the camera on the end, is advanced about a foot as the doctor looks at the lining of the intestine. Then a balloon at its end is inflated to anchor it. The outer tube is then pushed forward to near the end of the inner tube and is anchored in place with a second balloon.

This process is repeated over and over, letting the doctor see the intestine a foot at a time. The doctor can even take a biopsy if something abnormal is seen. This procedure is more involved than capsule endoscopy (and can take hours to complete), but it has the advantage of letting the doctor biopsy any lesions seen.

Kaposi sarcoma can also affect other organs, such as the liver, spleen, heart, or bone marrow. These areas do not often need to be biopsied in people already known to have Kaposi sarcoma based on biopsies of other tissues, such as skin, lungs, or intestines.

Survival rates for Kaposi sarcoma

Remember, these survival rates are only estimates – they can’t predict what will happen to any individual person. Talk to your doctor to better understand your specific situation.

As treatment of the HIV infection continues to improve, so does the outlook for people with Kaposi sarcoma. It takes time to see the effect of the most up-to-date treatment on survival rates, since they are based on patients first diagnosed many years ago. Early in the AIDS epidemic, the outlook for patients with Kaposi sarcoma was grim, with less than 10% of patients surviving at least 5 years after diagnosis. This has improved over time, with the most recent data from the National Cancer Institute’s SEER program showing an overall 5-year relative survival of about 74%. The cause of death for people with Kaposi sarcoma is not always the Kaposi sarcoma. Often, people with Kaposi sarcoma die from diseases related to HIV and AIDS, and not the Kaposi sarcoma itself.

Kaposi sarcoma treatment

For epidemic (AIDS-associated) and iatragenic (transplant related) Kaposi sarcoma, it is most important to treat any immune deficiency that exists, as well as any related infections.

For people with HIV or AIDS, this means using combinations of anti-HIV drugs. This is known as highly active antiretroviral therapy (HAART). For many AIDS patients, HAART may be the only treatment needed to to shrink the Kaposi sarcoma lesions and to keep them under control.

In organ-transplant patients whose immune systems are suppressed by drugs, stopping, lowering or changing the drugs may be helpful. Sirolimus and everolimus are new drugs that may control the Kaposi sarcoma lesions as well as prevent organ rejection.

New Kaposi sarcoma lesions are more likely to develop when a patient’s blood test results for Kaposi sarcoma herpesvirus are positive. The risk of developing new lesions is lower when antiviral medicines such as ganciclovir or foscarnet are used. These medicines may help prevent new lesions but they do not help existing lesions get better. They can also cause serious side effects.

Kaposi sarcoma lesions tend to get worse if you develop bacterial or other active infections. Therefore, it is very important to do what you can to lower your risk of bacterial infections and to treat active infections promptly if they do occur.

Treating localized lesions

Small, localized lesions are generally only treated if they are painful or they are causing cosmetic problems. It should be noted that lesions tend to recur after local treatments. Treatments include:

• Cryotherapy with liquid nitrogen
• Radiotherapy. This is most useful for classic Kaposi sarcoma and is less effective for HIV-associated disease.
• Surgical excision of individual nodules.
• Laser therapy, using pulsed dye laser or pulsed carbon dioxide laser
• Injection with anti-cancer drugs such as vinblastine
• Topical application of alitretinoin gel (Panretin®).
• Electrochemotherapy, a new treatment that uses electrical impulses to enhance effectiveness bleomycin or cisplatin injected into tumours.

Treating extensive or internal lesions with systemic therapy

A combination of anti-cancer drugs are given, but at lower than usual dosages if there is immunosuppression.

Other chemotherapy treatments that are used in some international centres include bleomycin, etoposide, paclitaxel, docetaxel and liposomal forms of the standard anti-cancer drugs, doxorubicin or daunorubicin. Liposomal means that the drugs are coated in small fat bubbles, or liposomes, which allows better absorption, resulting in less cardiac toxicity and myelotoxicity. Paclitaxel is approved for use in Kaposi sarcoma in advanced stages or as a second-line option.

Immunotherapy includes the use of interferon-alpha and imiquimod, sirolimus and thalidomide.

Kaposi sarcoma may arise in organ transplant patients. Switching from ciclosporin to sirolimus (rapamycin) has resulted in resolution of the sarcoma. This is largely attributed to the anti-proliferative and anti-angiogenic effects of sirolimus (mTor inhibitor).

Clinical trials into a wide range of other therapies are ongoing:

• Photodynamic therapy is a combination of a photosensitiser and light energy.
• Isotretinoin is a vitamin-A derivative usually used to treat acne.
• Bexarotene is used to treat cutaneous T-cell lymphoma.
• Cytokine inhibitors (biologics)
• The pregnancy hormone, human chorionic gonadotropin (HCG); Kaposi sarcoma lesions disappear in some women when they become pregnant.
• Ganciclovir, cidofovir and foscarnet (antiviral medications) have been recently reported to result in lower rates of Kaposi sarcoma amongst those being treated for CMV retinitis (inflammation of the retina caused by cytomegalovirus) and are currently being studied. Aciclovir, another antiviral, has been tried, but does not appear to work.
• Targeting vascular endothelial growth factor (VEGF): drugs acting on VEGF receptors like bevacizumab and sorafenib are being evaluated.
• The immune modulating agent lenolidamide is also under trial.