Patients with a certain type of advanced breast cancer are given new hope. The U.S. Food and Drug Administration releases an announcement, approving the first immunotherapy regimen for breast cancer.
The drug that received the green light is immunotherapy atezolizumab (Tecentriq), which is manufactured by Genentech Inc. The approved treatment also includes chemotherapy drug protein-bound paclitaxe (Abraxane). Along with this regimen, the FDA also granted approval to a Ventana PD-L1 Assay, which is a diagnostic apparatus used for choosing patients for atezolizumab.
Type Of Breast Cancer Involved
The approved treatment is not for all breast cancers. It is particularly indicated for triple-negative breast cancers that are metastatic and cannot be removed by surgery anymore. Another tumor criteria are the presence of a certain protein called PD-L1.
As the name implies, triple-negative breast cancers are those that are negative to the hormones estrogen, progesterone or human epidermal growth factor 2. This means that such cancers do not respond to hormonal regimens, typically prescribed for breast cancers.
Chemotherapy drugs may be good for this type of cancer, but it does not last. The cancer cells easily develop resistance to these drugs, paving the way for it to reach to other body parts.
Basis For Approval Of The Treatment
The approval comes after an international, double-blinded, randomized testing across different research centers. In the said trial, 902 patients with triple-negative breast cancer, who had not received chemotherapy yet were randomly selected to either take intravenous atezolizumab or placebo, plus protein-bound paclitaxel.
The researchers use Ventana PD-L1 Assay to test tumor samples in the central laboratory. They look after the median progression-free survival (PFS) rate, which is the length of time patients live with the disease without their condition advancing to another stage. For the placebo group, results show that PFS is 4.8 months, while for those who received atezolizumab, results were 7.4 months.
Dose, Route Of Administration And Adverse Effects
The regimen is performed within a 28-day cycle. Atezolizumab is given on days one and 15 via intravenous infusion over 60 minutes. The recommended dose is 840 mg. Treatment continues right after with 100 mg/m2 of protein-bound paclitaxel given on days one, eight, and 15 until toxicity develops or disease progresses.
Patients taking these medications may experience hair loss, nausea, fatigue, diarrhea, constipation, headache, cough, vomiting, and loss of appetite. In the study, more than 20 percent of participants reported such adverse reactions.
Contingent Approval
The FDA announcement is categorized under accelerated approval condition. This means that patients must exhibit an absence of disease progression while surviving the disease. Authorities also have to validate and describe the clinical benefit in confirmatory testing. Otherwise, approval is contingent.
The agency grants accelerated approvals to medications that treat serious diseases and can fill a medical need. Authorities do not necessarily have to have a direct measure of medical benefit.
Drug manufacturers are required to verify that the medication is advantageous through follow up testings. Once done, the drug may be able to receive the full, traditional FDA approval. For this case, Genentech Inc. is supposed to pass a final report of test results in September 2020.
The approval is good news to many. John Hopkins professor for oncology and epidemiology Dr. Otis Brawley thinks the FDA did the right thing but warns that this is not yet over.
"The FDA has approved it based on progression-free survival with the hope that later on ... data will show that the treatment actually makes women live longer," says Brawley.
The full approval is still underway and there are several trials and researches pending. Although conditional of some sort, the FDA announcement still gives a spark of hope to patients with breast cancers that are extra hard to treat. Hopefully, this is a sign of good things to come.
