PD-L1 Testing in India.l What is PL-L1, Where to get tested, and Cost of PD-L1 Test

Avishek Roy

Scientific Liaison Manager
4baseCare

PD-L1 AND CANCER

The immune system is crucial in keeping us healthy and removing the body’s diseased cells. By directing a coordinated immune response that includes innate and adaptive responses, the immune system’s T cells have the ability to specifically target and kill infections or unhealthy cells, including cancer cells. Numerous checkpoints make sure immune system cells do not unintentionally kill healthy cells during an immunological response. These immunological checkpoints can be used by cancer cells to avoid immune detection and destruction. The immune system can defeat cancer’s capacity to neutralize immune responses by blocking immune checkpoint proteins like PD-1, PD-L1, and CTLA-4 with monoclonal antibodies. This also stimulates the body’s mechanisms to continue to be effective in defending against cancer.

PD-1 and PD-L1 interaction of tumor cells and T cells [Immune checkpoint inhibitors of PD-L1 as cancer therapeutics. (2019, September 5). Journal of Hematology & Oncology.]

T cells that have been activated have the PD-1 (programmed cell death-1) receptor expressed on their surface. Dendritic cells and macrophages both express PD-1’s ligands, PD-L1/L2. The immune checkpoint protein family includes PD-1, PD-L1/L2, and others that function as co-inhibitory factors to slow or prevent the growth of the T cell response. In order to minimize the possibility of persistent autoimmune inflammation, the PD-1/PD-L1 interaction makes sure that the immune system is only activated when it is essential.

WHAT IS A PD-L1 TEST?

A protein called PDL1 aids in preventing immune cells from attacking healthy cells in the body. Normally, the immune system defends against outside invaders like bacteria and viruses rather than your own healthy cells. PDL1 is present at large levels in some cancer cells. A PD-L1 test measures the amount of this protein on cancer cells. This test is conducted to get a general understanding if a particular cancer patient can benefit from Immunotherapy or not. Immunotherapy boosts the immune system and aids in fighting cancer cells, thereby a patient with a high PD-L1 level will benefit from Immunotherapy. Patients with cancers like Non-small cell lung cancer, Melanoma, Hodgkin lymphoma, Bladder cancer, Kidney Cancer, and Breast cancer are normally found to have a higher PD-L1 expression.

Most PD-L1 tests are done via tissue biopsy which is basically a procedure to remove a piece of tissue or sample from the patient’s body to undergo further examination in a laboratory setting. There is no preparation as such to get a PD-L1 test but, this depends on the type of biopsy suggested by your clinician. In general, if general anesthesia is suggested, there is a preferable fast before the surgery and it is better to bring a caretaker with you to take care of the after-effects of anesthesia. A little bruising or bleeding at the biopsy site is a common occurrence and the physician will prescribe a few antibiotics to counter the same.

HOW ARE THE PD-L1 TEST RESULTS INTERPRETED?

The results of PD-L1 testing could indicate whether PD-L1 is expressed or not (present or absent) in tumor tissue, or they could be presented as a test-specific score. An interpretation will most likely be included in the report.

The patient who was tested is a suitable candidate for immunotherapy if PD-L1 protein is found on the tumor tissue. The immunotherapy will not always work on cancer patients with elevated PD-L1.

The likelihood that the patient will benefit from immunotherapy decreases if there is little or insufficient PD-L1, and a different course of treatment is likely to be pursued.

The other scoring method involves a Combined positive score (CPS) and tumor proportion score (TPS). In a laboratory test, a sample contains viable and non-viable cells. In the viable cells, there are intact cells that have the complete membrane and partially viable cells which have some cell damage. Now, the completely viable tumor cells are the ones considered in this scoring method.

CPS% tells us the number of PD-L1 positive cells which means the total number of viable cells whereas TPS% gives us an exact idea of the number of completely viable cells and partial viable cells. A minimum of 100 viable tumor cells is considered to be adequate to be PD-L1 evaluation.

PD-L1 TEST COST IN INDIA

A PD-L1 test costs around ₹4,000 – ₹12,000 in general. PD-L1 tests are offered in many labs such as Oncquest, DNA Labs, 4baseCare, etc. The packages offered by 4baseCare, a Precision Oncology company are designed focusing on Accessibility and Affordability. There NGS based Comprehensive Genomic Profiling panels such as TARGT Indiegene, TARGT Absolute, and TARGT Absolute+ offer not only PD-L1 testing but also cover a variety of known and novel genomic biomarkers which will identify the important genes causing the patient’s cancer type, thereby paving a way to Immunotherapy and Targeted Therapy.

REFERENCES :

1. Cancer immunotherapy and the PD1/PDL1 checkpoint pathway. (2020, December 7). Antibodies, Proteins, Kits and Reagents for Life Science | Abcam.
2. PDL1 (Immunotherapy) tests: MedlinePlus medical test. (n.d.). MedlinePlus – Health Information from the National Library of Medicine.
3. PD-l1. (2020, April 1). Testing.com.
4. PD-L1 expression testing information. (n.d.). KEYTRUDA® (pembrolizumab) | Indications and Efficacy Data for Health Care Professionals.