Tumor Vaccines

00:01 Another approach is to actually develop vaccines that you can immunize against tumors.

00:09 These could be prophylactic vaccines against virus-associated tumors.

00:14 And there are already a number of examples of those.

00:18 Liver cancer is linked to Hepatitis B virus, so immunizing against Hepatitis B virus should reduce the level of liver cancer.

00:28 Cervical cancer is associated with human papillomavirus.

00:32 Currently, Gardasil 9, which protects against 9 HPV types.

00:37 6, 11, 16, 18, 31, 33, 45, 52, and 58 and is recommended for both males and females.

00:49 HPV can cause several types of cancers including cervical, anal, penile, and oropharyngeal cancers, as well as genital warts.

00:59 Of course very often one may need to treat a patient that has already developed a tumor.

01:05 For tumor antigens, in most cases the aim is primarily to induce specific cytotoxic T-cell responses.

01:12 But sometimes antibody may also be desirable.

01:16 The vaccine provenge, which is a prostate cancer vaccine uses the patient’s own cells to develop a vaccine.

01:25 Some tumor vaccines target dendritic cells in vivo.

01:30 One approach conjugates the tumor antigen to an antibody that binds to dendritic cell surface molecules like DEC205.

01:40 This helps deliver the tumor antigen directly to dendritic cells, which can then process it and present it to T-cells, potentially generating a stronger immune response.

01:54 And then the tumor antigen will be taken up by the dendritic cells, processed and presented to T-cells.

02:03 Monocytes or CD34+ precursors can be loaded with tumor antigens and differentiated into dendritic cells using cytokines, such as granulocyte macrophage colony stimulating factor and interleukin-4.

02:20 So you take patient cells, incubate them with the antigen, make the dendritic cells develop from the blood monocytes.

02:30 And then re-infuse the dendritic cells back into the patient.

02:35 Provenge or Sipuleucel-T is approved by the FDA for the treatment of asymptomatic or minimally symptomatic metastatic castrate-resistant (hormone-refractory) prostate cancer.

02:51 In this strategy on day one, the patient undergoes leukapheresis to isolate precursors of dendritic cells.

03:04 Prostatic acid phosphatase linked to the cytokine GM-CSF is incubated with these isolated blood cells.

03:16 And over the course of two or three days, the GM-CSF causes differentiation of these blood leukocytes into dendritic cells.

03:26 And the prostate acid phosphatase tumor antigen gets delivered via these dendritic cells, when infused back into the patient.

03:39 T-cells within the patient will become activated, that are specific for this tumor antigen.

03:45 The whole process is repeated at weeks two and four.