Vaccines are usually given before we actually get infected, as a form of preventative medicine.

疫苗通常是在我們真正受到感染之前接種的，是一種預防性藥物。

But cancer researchers are also developing vaccines that could be used as treatments after cancer has been found.

不過，癌症研究人員也在開發疫苗，可在發現癌症後用於治療。

The idea is to teach the body's immune system to recognise the cancer cells and then kill them. There are several ways to do this.

其目的是讓人體的免疫系統識別癌細胞，然後將其殺死。有幾種方法可以做到這一點。

Every cell in the body is surrounded by a cell membrane with proteins embedded in it.

人體內的每個細胞都被細胞膜包圍著，細胞膜上嵌有蛋白質。

Inside cells, there are proteins too.

細胞內也有蛋白質。

Cancer cells make proteins found nowhere else in the body.

癌細胞製造的蛋白質在人體中找不到。

Think of them like a barcode.

把它們想象成條碼。

The simplest type of cancer vaccine takes a single protein commonly found in one type of cancer and teaches the immune system to react to it.

最簡單的癌症疫苗是利用一種癌症中常見的單一蛋白質，讓免疫系統對其產生反應。

The protein, or antigen, is injected into the body where an immune cell called a dendritic cell ingests it.

蛋白質或抗原被注射到體內，一種名為樹突狀細胞的免疫細胞會將其攝入體內。

The dendritic cell then activates another class of immune cells called T-cells, and these attack the cancer.

然後，樹突狀細胞會激活另一類名為 T 細胞的免疫細胞，這些細胞會攻擊癌症。

This method is straightforward, and hospitals could have a supply of vaccines in the fridge for the most common types of cancer.

這種方法非常簡單，醫院的冰箱裡就有針對最常見癌症類型的疫苗。

But in trials, these vaccines haven't always worked. So researchers are now trying to target patients' tumors more specifically.

但在試驗中，這些疫苗並不總是有效。是以，研究人員現在正試圖更有針對性地靶向患者的腫瘤。

As tumors grow, they mutate, which means they change.

隨著腫瘤的生長，它們會發生變異，這意味著它們會改變。

The unique proteins that each patient's tumor acquires as it mutates are known as neoantigens.

每個患者的腫瘤在變異過程中獲得的獨特蛋白質被稱為新抗原。

And these neoantigens are being tested as the basis for personalized vaccines.

這些新抗原正在作為個性化疫苗的基礎進行測試。

First, a sample of the patient's tumor is taken.

首先，提取患者的腫瘤樣本。

The tumor cells contain messenger RNA, which carries the genetic instructions for making proteins.

腫瘤細胞中含有信使核糖核酸，它攜帶著製造蛋白質的遺傳指令。

The mRNA is extracted and sequenced along with the cell's DNA to identify the instructions for the tumor's unique proteins, its neoantigens.

提取 mRNA 並與細胞 DNA 一起進行測序，以確定腫瘤獨特蛋白質（新抗原）的指令。

The ones predicted to most powerfully stimulate the immune system are selected and injected into the body for the dendritic cells to find.

預測能最有力地刺激免疫系統的樹突狀細胞被選中並注射到體內，供樹突狀細胞尋找。

This kind of bespoke mRNA vaccine is showing exciting promise for treating melanoma and pancreatic cancers. There's another way to make personalized vaccines that doesn't involve genetic sequencing.

這種定製的 mRNA 疫苗在治療黑色素瘤和胰腺癌方面顯示出令人振奮的前景。還有一種不涉及基因測序的個性化疫苗製造方法。

Again, a tumor sample is taken.

再次採集腫瘤樣本。

But this time, the proteins are extracted from the cancer cells and then, without identifying the proteins, introduced to a sample of the patient's dendritic cells in a Petri dish.

但這次是從癌細胞中提取蛋白質，然後在不對蛋白質進行鑑定的情況下，將其引入培養皿中的患者樹突狀細胞樣本中。

When the dendritic cells are injected back into the body, they stimulate T-cells to recognize and attack the cancer. Personalized vaccines may be very powerful, but making them anew for every patient is costly and time-consuming.

當樹突狀細胞被注射回體內時，它們會刺激 T 細胞識別並攻擊癌症。個性化疫苗可能非常強大，但為每位患者重新制造疫苗既昂貴又耗時。

So scientists are also working on off-the-shelf treatments where the vaccination process occurs completely within the patient's body.

是以，科學家們也在研究現成的治療方法，讓疫苗接種過程完全在患者體內進行。

Patients are given drugs that activate dendritic cells, as well as a treatment like radiotherapy that kills cancer cells.

患者會服用能激活樹突狀細胞的藥物，並接受能殺死癌細胞的放療等治療。

The dying cancer cells release their proteins, which are mopped up by the switched-on dendritic cells.

垂死的癌細胞會釋放出蛋白質，這些蛋白質會被啟動的樹突狀細胞清除。

These cells then present the cancer proteins to T-cells, stimulating the T-cells to attack the cancer.

然後，這些細胞將癌細胞蛋白呈現給 T 細胞，刺激 T 細胞攻擊癌症。

All of these approaches are still being developed and tested.

所有這些方法仍在開發和測試之中。

If trials continue to go well, vaccines that boost the body's own immune defenses look set to become another tool in our efforts to defeat cancer.

如果試驗繼續順利進行，增強人體自身免疫防禦能力的疫苗有望成為我們戰勝癌症的又一工具。