The Use Of Oncolytic Viruses For Cancer Treatment

In the first place, preliminary experiments indicate that the use of oncolytic viruses for cancer treatment may become a reality. There are several lines of research that point to the fact that oncolytic viruses can make a difference in treating incurable cancer patients.

Notably, Canadian researchers had reported in 2011 that oncolytic viruses created by genetically modifying smallpox vaccine viruses would enter tumor cells of patients, but not damage normal cells. Specifically, a high percentage of the end stage patients responded with tumor regression.

Shortly after Mayo Clinic physicians were desperate when two patients with end stage multiple myeloma, a vicious bone tumor, did not respond to chemotherapy. Significantly, they tried something unconventional: high doses of the measles vaccine in an attempt to stimulate the immune system. Here is an overview from 2014 that shows that many different cancers respond to various immunological approaches.

Study from Holland regarding end stage melanoma patients

Here is a small human study involving end-stage melanoma patients treated with the oncolytic virus T-VEC combined with pembrolizumab (Keytruda). It is important to realize that Keytruda helps to reactivate a T-cell response to the cancer cells. In this case the cancer cells absorb the oncolytic virus (T-VEC), but it leaves normal cells alone. Inside the cancer cells the oncolytic virus multiplies and destroys the cancer cells. In this 2017 study 21 patients with terminal, nonresectable melanoma received treatment with T-VEC and Keytruda. Specifically, 62% of the patients showed an objective response to the treatment. Moreover, 33% fulfilled the criteria of an immune-related response. In the past terminal patients like these had a 0% response to radiotherapy or chemotherapy.

History of research about oncolytic viruses

To begin with, in 1912 rabies virus treatment against cervical carcinoma was a first attempt to treat cancer. Researchers conducted many experiments between 1950 and 1970 with wild type or naturally attenuated viruses. This included, for example, hepatitis A and B viruses. In 1991 cancer researchers developed the concept of genetically engineered oncolytic viruses. Today cancer researchers know that the protection mechanisms in most cancer cells have deficiencies. This involves the interferon‐beta signal pathway. Having said this, there is an opportunity to let oncolytic viruses destroy cancer cells, while normal cells stay unaffected. An oncolytic virus that cancer experts use in human cancers is the genetically engineered herpes simplex virus type I (HSV‐1). Others that cancer researchers developed have strange names like T‐Vec, G47∆, JX594, CG0070 and Reolysin.

Various cancers that researchers treated with oncolytic viruses

Here are a few examples of cancers where researchers used oncolytic viruses to exert a significant therapeutic effect.


Glioblastoma is a deadly form of a brain tumor, which has a high rate of mortality. Researchers have investigated new avenues to treat this cancer. Researchers tested the genetically engineered dendritic vaccine. Initial clinical trials showed significant effectiveness compared to non-treated controls. In a large phase 3 clinical trial 331 patients with newly diagnosed glioblastoma received treatment at the time of neurosurgery with dendritic cell vaccine. 30.2% of the patients were still alive and doing well after 3 1/3 years. Without the added vaccination procedure all of these patients would have died in the past because of the aggressiveness of the glioblastoma.

Multiple myeloma

Researchers could cure multiple myeloma and other cancers by using the measles vaccine. Here is a report by the popular press about two women who had multiple myeloma. One woman got cured by high doses of a measles vaccine. The other women experienced some relief, but did not survive.

This publication explains that oncolytic viral therapy of cancer is a lot more complicated than originally thought.

Prostate cancer

Researchers found that vaccines against prostate cancer were effective with the combination of oncolytic virus therapy with regular anti-cancer treatments. But oncolytic virus therapy alone has a poorer prognosis than a combination of chemotherapy or radiotherapy with oncolytic virus therapy.

Cervical cancer

The high-risk HPV16 strain most often causes cervical cancer. The HPV (human papilloma virus) vaccine targets patients with previous exposure to HPV16. However, researchers have noticed that in some cases a phenomenon called the “HPV immune escape” has allowed in some vaccinated women to still develop cervical cancer. Now a group of researchers are investigating how the vaccine could be improved by finding out how the immune system is being tricked in these cases by the HPV virus to bypass the antibodies of the vaccine.

Pancreatic cancer

This cancer is very difficult to detect in the early stages, and as a result the outlook for chemotherapy or radiotherapy is extremely poor. Researchers have used several approaches as an alternative to conventional therapy. Immunotherapy is an option. Mayo clinic researchers have already announced that the measles vaccine approach will likely be applicable to pancreatic cancer treatment as well in the near future. However, other clinical trials are on the way to use alternative vaccination procedures.

Neuroblastoma, glioma and melanoma

This link shows that the FDA has accepted engineered oncolytic herpes virus (engineered to secrete GM-CSF) as a treatment against melanoma. Other approaches with engineered bacteria can affect neuroblastoma and glioma.

Survival data using oncolytic viruses for cancer treatment

Cancer researchers have completed a number of smaller clinical trials at this point. One of them describes end stage melanoma (stage III and IV) where the only treatment was with the oncolytic virus T‐Vec. The overall response rate compared to the control, which was only 5.7%, the experimental group with T-Vec was 26.4%. This is considered a good response rate given that we are dealing with end stage melanoma patients.

Mechanism of how oncolytic viruses stimulate the immune system to overcome various cancers

As mentioned above oncolytic viruses multiply in the cancer, once they have been incorporated. This leads to cancer cell death. It exposes the dead cancer tissue to the immune system. What helps in the process is that inhibitory proteins from the cancer cells that used to inhibit the immune system are no longer provided by the dead cancer cells. The end result is that the immune system mounts a formidable response against the cancer cells through killer T cells. This immune response also affects remote metastases of the same histological cancer type. This review article summarizes how oncolytic viruses work for cancer cell destruction and how this method can be combined with other treatment modalities.

The Use Of Oncolytic Viruses For Cancer Treatment

The Use Of Oncolytic Viruses For Cancer Treatment


Currently various cancer centers are involved with clinical trials in humans to test the power of oncolytic viruses. What cancer researchers have learnt is that oncolytic viruses are a useful tool to kill cancer cells. But the immune system of cancer patients is in a suppressed state. Pembrolizumab (Keytruda) is a medication that will stimulate the immune system by stimulating killer T cells to destroy cancer cells. The combined effect of killing cancer cells with oncolytic viruses and stimulating the immune system is the big news. This has been the breakthrough that cancer researchers have been waiting for. Now several clinical trials are on the way where survival rates for cancer patients given the new combination therapy are assessed.

Oncolytic virus therapy here to stay

It is a treatment which is no longer a thought model with animal experiments. Well known medical centers are using it in patients, and as the results become more obvious, it will very likely become a new treatment modality for cancer.

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Staying Healthy During Exotic Travel

A study of 82,825 ill travelers from Europe, North America, Israel, Japan, Australia and New Zealand was published who were interested in staying healthy during exotic travel. They had traveled the world between June 1996 and August 2011. The data was based on the GeoSentinel surveillance network database. There were 3,655 patients (4.4%) who were seriously sick with one of 13 tropical diseases. There were 13 deaths (=0.4%), 10 of which were from malaria. Two died from melioidosis. This is an infectious disease caused by a bacterium found in soil in Southeast Asia (including Thailand, Laos, southern China, Singapore, Malaysia, Burma and Vietnam), Taiwan and northern Australia. One person died from severe dengue. The interesting fact is that there was not a single case of Ebola virus, although this is a highly publicized and lethal illness in Africa. The majority of travelers sustained malaria and typhoid.

The tropical diseases were either due to viral illnesses, bacterial infections or protozoan infections.

Frequent viral illnesses encountered by visitors to Asia were dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS); avian influenza, Lassa fever as well as other tropical hemorrhagic fevers, Japanese encephalitis including other tropical encephalitis cases, Rift Valley fever and yellow fever.

This is a list of the bacterial infections that were reported: Anthrax, Carrion’s disease (=Bartonella bacilliformis), epidemic typhus, leptospirosis, melioidosis, murine typhus, paratyphoid fever, plague, relapsing fever, scrub typhus, spotted fever group rickettsioses and typhoid fever.

An interesting side-note is that even in familiar places like Hawaii leptospirosis is re-emerging as this link shows. So, it is important for visitors to Kauai and the Big Island of Hawaii (Waipio valley) to refrain from swimming in streams or natural ponds and to not expose your face to cascading waterfalls as leptospirosis can enter through the eyes, the nose, the mouth and scratches on the skin.

Finally, the following protozoan infections were found frequently: East African sleeping sickness, falciparum malaria and Plasmodium knowlesi malaria.

Staying Healthy During Exotic Travel

Staying Healthy During Exotic Travel

Each travel region has its special infection characteristics. With travel to Central America infectious diseases ranked in decreasing frequency like this: typhoid fever, leptospirosis, falciparum malaria and paratyphoid fever. In the Caribbean falciparum malaria was followed by typhoid fever, leptospirosis and paratyphoid fever. In South America the highest on the list was again falciparum malaria, followed by typhoid fever, paratyphoid fever and leptospirosis. In Sub Saharan Africa the highest number of falciparum malaria cases were registered (2633 of them), followed by 42 cases of typhoid fever, paratyphoid fever and leptospirosis. In the Middle East only one case of falciparum malaria, one case of typhoid fever and 2 cases of paratyphoid fever were reported. In contrast there were many more infections reported in South Central Asia (India): 286 cases of typhoid fever, followed by parathyroid fever, falciparum malaria and leptospirosis. All of the cases of typhoid fever and parathyroid fever in India were adequately treated with antibiotics and no deaths resulted from that. This is an example where no vaccine is available for prevention, but swift medical treatment could help immediately when an infection had occurred.

In South East Asia (Malaysia, Philippines, Indonesia) leptospirosis was on top, followed by typhoid fever, falciparum malaria and parathyroid fever. North East Asia (Korea, Mongolia), had only 3 cases of typhoid fever and 1 case of paratyphoid fever. Oceania (Polynesia) reported 26 cases of falciparum malaria, followed by paratyphoid fever and typhoid fever.

Several interesting observations were made with regard to this study.

  1. Most patients with travel acquired tropical illnesses presented within less than 17 days at the doctor’s office at home and 91% of them had developed a fever.
  2. The spectrum of the tropical disease that was diagnosed and treated varied according to the geographic destination where the traveler had been, which is consistent with the observations mentioned above (different distribution of tropical diseases depending on which area was traveled). Visitors to West Africa had a high rate of falciparum malaria, visitors to India sustained largely enteric fevers; and leptospirosis,  scrub typhus and murine typhus were the dominant tropical diseases for visitors to South East Asia.
  3. Males were found to be less diligent in using chemoprophylaxis for malaria prior to their travel than females. Overall only a minority had attended a travel clinic prior to their travel for immunizations and chemoprophylaxis for preventable tropical disease such as malaria.
  4. Other global life-threatening diseases like meningitis, other forms of septicemia, severe bacterial pneumonia and legionnaires also have to be considered as they occurred in roughly 30% of returning travelers.
  5. Malaria was the largest percentage of the tropical diseases that travelers brought home and 67% of all cases were male patients. They were mostly visiting West Africa where they acquired malaria (typically from Nigeria,  Ghana and the Ivory Coast). As mentioned they accounted for 10 of the 13 deaths.

The authors recommend that travelers should prepare themselves for trips to the tropics and subtropics, preferable visiting one of the travelers’ clinics. The recommended procedures should be followed meticulously. Not all of the diseases can be prevented, but if the traveler turns sick, they should seek medical advice as soon as possible in the country where they travel as these physicians often have special expertise in these tropical diseases.

One of the comments of the study was that often people visit relatives and friends in an area where tropical disease exists without any chemoprophylaxis or vaccinations beforehand. The visitors were under the impression that prior living in the area as a child would still protect them now during the travel as an adult, which is not the case. This can be prevented by visiting a travel clinic well before the planned trip, so there is enough time for vaccinations and possible blood tests.  

More information on:

1. Traveler’s diarrhea:

2. Parasites: