Last week FDA has approved Keytruda (pembrolizumab) a special treatment of cancer with particular genetic feature (biomarker). This is the first case of treating cancer based on the biomarker, not tumor affected body part.
Keytruda is directed to the treatment of adults and children with unresectable or metastatic tumors, which were identified with biomarker MSI-H or dMMR. This indication covers patients with solid tumors that have progressed following prior treatment and who have no satisfactory alternative treatment options and patients with colorectal cancer that has progressed following treatment with certain chemotherapy drugs.
MSI-H or dMMR indicated tumors affected to the barrier, which does not allow to restore DNA inside the cell properly. Such tumors occur in the case of endometrial, colorectal and gastrointestinal cancer, also breast, prostate, bladder, thyroid gland cancer, etc.
Keytruda affects cellular pathway PD-1 and PD-L1, blocks it and stimulates patient’s immune system to fight cancer cells. This treatment was already approved by FDA in cases of metastatic melanoma, lungs, neck and brain cancer, refractory classical Hodgkin lymphoma, and urothelial carcinoma.
Keytruda was accepted within Accelerated Approval pathway, created for implementing to treatment cases of unmet medical needs and drugs, potentially bringing clinical benefits to patients. The follow-up studies are directed to indicating and confirming of awaited Keytruda’s effects, so, the sponsor conducts them.
The efficacy and safety of treatment were studied during 5 uncontrolled trials with the participation of patients, 149 of them were indicated with one of 15 types of cancer. The most of them are colorectal, endometrial or gastrointestinal cancer. 39,6% from these 149 were indicated the positive response to the treatment, 78% from 39,6% this positive response continued for 6 months or more.
Keytruda’s side-effects are fatigue, itchy skin, diarrhea, decreased appetite, rash, fever, cough, dyspnea, musculoskeletal pain, constipation, and nausea. Keytruda can cause serious conditions known as immune-mediated side effects, including inflammation of healthy organs such as the pneumonitis, colitis, hepatitis, endocrinopathies and nephritis.