As a result of the drug’s success, “we’re beginning to see more broad acceptance of immunotherapies in the oncology community at large, and it certainly defines immunotherapy as a treatment modality for cancer,” Hoos noted. “It makes it more likely there will be further investigations that are successful.”
Illustration depicts a spacefill model of an antibody. The use of monoclonal antibodies in cancer immunotherapy has been highly successful.
Researchers Battled Skepticism
If success breeds success for immunotherapy approaches this time around, past disappointments have made researchers feel as though they were fighting for acceptance of their theories.
The cycle has been one of soaring hopes dashed by clinical realities. In the 1970s, developing monoclonal antibodies (mAbs) generated so much excitement that they were touted as “magic bullets,” according to a report from the Cancer Research Institute and MD Becker Partners LLC (Report
Disappointment set in when it took until 1997 for the fi rst drug in the class, rituximab (Rituxan), to gain approval. Now, the passive immunotherapy drugs are “one of the most successful therapeutic classes,” the report notes.
Likewise, active immunotherapies at first proved disappointing.
“In part, those disappointments have come from some of the vaccine approaches that were promising in the early going and did not pan out in clinical trials,” said Gajewski.
He said, though, that when bright prospects dimmed, “it forced researchers to try and fi gure out the mechanisms,” and that has in turn helped identify barriers to immune functions, which are now being targeted.
At its heart, immunotherapy is defined as biologic therapy that uses parts of the immune system to fight cancer, with therapy approaches broadly defined as active, passive, and targeted immunotherapies, according to the American Cancer Society.
FDA-Approved Cancer Immunotherapies
Non-Hodgkin lymphoma (NHL)
Chronic lymphocytic leukemia (CLL)
Acute myelogenous leukemia
Ibritumomab tiuxetan* (Zevalin)
Head & neck cancers
Non-small cell lung cancer
Renal cell carcinoma (RCC)
Cancer spread to bone
(denileukin diftitox, Ontak)
Cutaneous T-cell lymphoma
Interferon alfa-2b (Intron A)
Hairy cell leukemia
Bacille Calmette-Guérin(TICE BCG)
Multiple myeloma (MM)
Sources: American Cancer Society, Drugs @ FDA database, prescribing information for individual drugs.
* Conjugated monoclonal antibodies that are radiolabeled
† Approval withdrawn as of October 15, 2010; this drug is only available for use within a clinical trial
Indication under FDA review
‡ Human papillomavirus and hepatitis B vaccines target viruses that can cause cancer and are not considered immunotherapy vaccines
** Initial FDA approval for treating erythema nodosum leprosum
While many forms of immunotherapy are under investigation, the society said FDA-approved options include 12 mAbs, 2 cytokines/proteins, and 2 immunomodulating agents.