PD-L1 is an important predictive biomarker for treatment by immune checkpoint inhibitors (ICIs). ICIs are now indicated for the treatment of various cancer depending on the level of expression of PD-L1 on tumor cells. PD-L1 testing is done using immunohistochemistry with five different assays approved as companion diagnostic for ICIs. However, these assays have different score reporting methods and do not accurately measure PD-L1 expression. Exosomal PD-L1 testing has recently emerged as an alternative for cell-surface PD-L1 testing however studies are still premature and more extensive knowledge about this new potential biomarker is needed.
Lung cancer is the second most common cancer worldwide and the leading cause of death among cancers. The progressive approvals of immunotherapy as first-line treatment options have helped improve cancer prognosis. However, longer follow-up has confirmed the possibility of acquired resistance to immune checkpoint inhibitors (ICIs) which can lead to late relapses. Chemotherapy can act as a priming therapy to increase a tumor’s response to immunotherapy. We aim through this review to explain the mechanism behind ICI resistance and the value of chemotherapy in escaping this resistance. Finally, all US FDA approvals regarding the management of metastatic non-small-cell lung cancer using a combination of ICIs and chemotherapy are summarized.
Metastatic colorectal cancer is the second most common cause of cancer death. Standard chemotherapy in combination with targeted therapies represent the backbone for the treatment of advanced disease. However, options are limited for patients progressing on these regimens. Genetic testing can offer patients the opportunity to benefit from novel therapies, namely immune checkpoint inhibitors in microsatellite instability-positive tumors. HER2 overexpression has recently emerged as a potentially targetable tumor marker in colorectal cancer (CRC). Despite the absence of approvals for anti-HER2 therapies in CRC, many agents such as trastuzumab and pertuzumab were tested and demonstrated significant antitumor activity, even in heavily pretreated patients. Early trials are also evaluating lapatinib, T-DM1, tucatinib and other anti-HER2 agents in patients with metastatic CRC, with promising results.
Immunotherapy has improved the prognosis of many cancers, yet a large number of patients have demonstrated resistance to current immune checkpoint inhibitors. LAG-3 is an immune checkpoint expressed on tumor-infiltrating lymphocytes CD4+ and CD8+, Tregs and other immune cells. Coexpression of PD-1 and LAG-3 in solid or hematological cancers is generally associated with a poor prognosis and may be responsible for immunotherapy resistance. Dual inhibition therapy in the RELATIVITY-047 trial significantly improved progression-free survival in metastatic melanoma. This article discusses the presence of a possible synergistic interaction between LAG-3 and PD-1 in the tumor microenvironment and the utility of targeting both immune checkpoint inhibitors as an effective way to bypass resistance and increase treatment efficacy.
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