Immunotherapy involves the use of drugs to boost patients' immune system response, increasing the attack on cancer cells.
Recently presented at the 2015 American Society for Clinical Oncology annual meeting, one study revealed that a drug combination of ipilimumab and nivolumab (an immune therapy drug) reduced tumor size in almost 60% of individuals with advanced melanoma - the deadliest form of skin cancer - compared with ipilimumab alone, while another study found nivolumab reduced the risk of lung cancer death by more than 40%.
Nivolumab is a drug already approved by the Food and Drug Administration (FDA) for the treatment of metastatic melanoma in patients who have not responded to ipilimumab or other medications. It is also approved for the treatment of non-small cell lung cancer (NSCLC) that has metastasized during or after chemotherapy.
According to cancer experts, however, the results of these latest studies indicate that nivolumab and other immune therapy drugs could one day become standard treatment for cancer, replacing chemotherapy.
Prof. Roy Herbst, chief of medical oncology at Yale Cancer Center in New Haven, CT, believes this could happen in the next 5 years. "I think we are seeing a paradigm shift in the way oncology is being treated," he told The Guardian. "The potential for long-term survival, effective cure, is definitely there."
Nivolumab plus ipilimumab reduced tumor size by at least a third for almost 1 year
Nivolumab belongs to a class of drugs known as "checkpoint inhibitors." It works by blocking the activation of PD-L1 and PD-1 - proteins that help cancer cells hide from immune cells, avoiding attack.
In a phase 3 trial, Dr. Rene Gonzalez, of the University of Colorado Cancer Center, and colleagues tested the effectiveness of nivolumab combined with ipilimumab - a drug that stimulates immune cells to help fight cancer - or ipilimumab alone in 945 patients with advanced melanoma (stage III or stage IV) who had received no prior treatment.
While 19% of patients who received ipilimumab alone experienced a reduction in tumor size for a period of 2.5 months, the tumors of 58% of patients who received nivolumab plus ipilimumab reduced by at least a third for almost a year.
Commenting on these findings, study co-leader Dr. James Larkin, of the Royal Marsden Hospital in the UK, told BBC News:
"By giving these drugs together you are effectively taking two brakes off the immune system rather than one, so the immune system is able to recognize tumors it wasn't previously recognizing and react to that and destroy them.
For immunotherapies, we've never seen tumor shrinkage rates over 50% so that's very significant to see. This is a treatment modality that I think is going to have a big future for the treatment of cancer."
Dr. Gonzalez and colleagues also demonstrated the effectiveness of another immune therapy drug called pembrolizumab in patients with advanced melanoma.
While 16% of 179 patients treated with chemotherapy alone experienced no disease progression after 6 months, the team found that disease progression was halted for 36% of 361 patients treated with pembrolizumab after 6 months.
Dr. Gonzalez notes that while a combination of nivolumab and ipilimumab shows greater efficacy against advanced melanoma than pembrolizumab, it also presents greater toxicity. Around 55% of patients treated with nivolumab plus ipilimumab had severe side effects, such as fatigue and colitis, with around 36% of these patients discontinuing treatment.
Dr. Gonzalez says such treatment may be better for patients whose cancer does not involve overexpression of the PD-L1 protein.
"Maybe PDL1-negative patients will benefit most from the combination, whereas PDL1-positive patients could use a drug targeting that protein with equal efficacy and less toxicity," he adds. "In metastatic melanoma, all patients and not just those who are PD-L1-positive may benefit from pembrolizumab."
Nivolumab almost doubled patient survival from NSCLC
In another study, Dr. Julie Brahmer, director of the Thoracic Oncology Program at the Johns Hopkins Kimmel Cancer Center, and colleagues tested the effectiveness of nivolumab against standard chemotherapy with the drug docetaxel among 260 patients with NSCLC.
All patients had been treated for the disease previously, but the cancer had returned and spread.
The team found that patients who received nivolumab had longer overall survival than those treated with standard chemotherapy, at 9.2 months versus 6 months.
At 1 year after treatment, the researchers found nivolumab almost doubled patient survival. Around 42% of patients who received nivolumab were alive after 1 year, compared with only 24% of patients who received chemotherapy.
The study results also demonstrated a longer period of halted disease progression for patients who received nivolumab compared with those who had chemotherapy, at 3.5 months versus 2.8 months.
Overall, the researchers estimated that, compared with patients who received chemotherapy, those who received nivolumab were at 41% lower risk of death from NSCLC.
Commenting on these findings, Dr. Brahmer says:
"This solidifies immunotherapy as a treatment option in lung cancer. In the 20 years that I've been in practice, I consider this a major milestone."
While both studies show promise for the use of immunotherapy in cancer treatment, experts note that such treatment would be expensive. The use of nivolumab plus ipilimumab for the treatment of advanced melanoma, for example, would cost at least $200,000 per patient.
As such, researchers say it is important that future research determines which cancer patients would be most likely to benefit from immunotherapy.
Medical News Today recently reported on a study conducted by investigators from Cancer Research UK, which reveals a class of drugs called AKT inhibitors may boost the effect of radiotherapy against various cancers, including breast, kidney, melanoma and brain cancers.