Adjunct downstream inhibition of the cyclin-dependent kinase (CDK 4/6 pathway, intended to delay and prevent endocrine therapy resistance, has further extended progression-free survival in patients receiving endocrine therapy; however, resistance still eventually develops in these patients.
These regimens extended progression-free survival to more than 8 months [ 4].
All of these studies have reported a high response rate and extended progression-free survival (PFS) period, compared with historical controls.
A randomized trial has shown that maintenance therapy with PARP inhibitors extended progression-free survival by almost 4 months in patients with high-grade serous ovarian cancer with or without BRCA1 or BRCA2 germline mutations.
When combined with chemotherapy in relapsed or refractory ovarian cancer, bevacizumab has significantly extended progression-free survival, although its impact on overall survival is still unclear 7, 8, 16.
Results from the clinical evaluation of pertuzumab and trastuzumab (CLEOPATRA) study have demonstrated that addition of pertuzumab to trastuzumab plus docetaxel extended progression-free survival from 12.4 to 18.5 months for HER2-positive metastatic breast cancer indicating the clinical benefit from combination of these two antibodies (Baselga et al, 2012).
Third, response to systemic therapy has been proven effective in extending progression free survival and OS in metastatic STS [ 27], while neoadjuvant chemotherapy was reported to associate with improved disease free survival and OS [ 7].
Moreover, sunitinib has been shown to extend progression free survival and overall survival in patients with metastatic renal cell carcinoma (mRCC) and is now used as first line treatment for this disease [ 44, 45].
Reportedly, antiplatelet or anticoagulant drugs extend progression-free survival in patients with progressive cancer [ 5, 6].
The introduction of anti-angiogenic drugs into clinical practice has demonstrated that inhibition of tumor angiogenesis, mostly in combination with chemotherapy, extends progression-free and overall survival in several cancers [49].
