Benefits Of Early HLA Typing (Stemmatch): Clinical Relevance

A parachute, a lifebuoy, a safety jacket - what’s common between them? Yes, you’re right, they’re all used as safety gears. You may not use them immediately, but their mere presence at an arm’s length is reassuring that you can count on it in times of an emergency. Now, imagine having a similar back-up for a stem cell transplantation. Something that acts as a reassurance of yours and your family’s health when an urgent need for a matching donor arises? This is exactly where early HLA typing fits in.

Curious to know how? Before we dive (without a lifebuoy) right into the details, let’s quickly brush-up our know-how about HLA- or Human Leukocyte Antigens!

Human Leukocyte Antigens - Nature & Role In Transplants

HLA (human leukocyte antigen) are proteins or markers present on almost all cells of the body. Our immune system uses HLA to recognize our own cells and foreign bodies¹.

Since HLAs are inherited, sometimes even siblings can be a good match with a 25% chance of being a complete or perfect match. A 6 out of 8 HLA match (~75%) between the patient & the donor is sufficient for cord blood stem cell transplant². Even those belonging to the same ethnicity as yours can also be a good match.

In case of a transplant, the doctors always try to find a close match between the donor and recipient’s HLA markers, a process known as HLA typing. For this, first the recipient’s blood sample or cheek swab is collected. The sample is then compared with similar samples collected from potential donors and a closest match is chosen.

HLA typing helps in the following ways¹:

• Reduce the risk of complications including graft-versus-host disease (GVHD). GVHD is a complication that occurs when the immune cells of the host attack the donated graft cells as an act of defense.
• Promote engraftment or development of new healthy blood cells.
• Improves chances of a successful transplantation.

One needs to remember that in any transplantation process, however, time is of essence. While a delay is never intended, getting the right donor match could, at times, prove to be an uphill task. Let us briefly discuss the cause of these hurdles.

Hurdles In Finding Matching Donors

Some of the common hurdles you might encounter while looking for a matching donor for transplantation are:

• Finding the match from your own ethnicity in the world wide public banks.
• Low inventories at public bank repositories
• Donor drop out at the last minute
• Delay in processing requests 

What makes this journey even more difficult is finding a matching donor of Indian-origin, which further narrows down our options. Here’s why:

Low Ethnic Donor Representation In Registries

With the ever-increasing number of transplants occurring worldwide, the trend of hematopoietic stem cells transplantation using cells matched with an unrelated donor is also increasing. This trend has also led to a spurt in the number of voluntary donors to the Bone Marrow Donor Worldwide (BMDW) registry. However, some ethnic populations are poorly represented in the BMDW with the probability of finding a match for an Indian patient being only 16%. This dismal representation puts the focus on enhancing and improving the number of Indian donors in an Indian or multinational registry³.

This scenario is no better in national registries too. The probability of finding the right stem cell match from an unrelated donor of Indian origin is 1 to 10,000 to 1 to 1 Million, depending on how closely the donor-recipient HLA typing matches⁴.

Diverse Ethnic Background

India has a population of 1.3 billion plus. However, only about 4 lakh people are registered as blood stem cell donors. With ethnicity playing a vital role when finding a right match, India's huge diverse ethnic background makes it all the more challenging. Additionally, each patient has only a 30% probability of finding a match within their own family. This leaves the rest of 70% to search for a matching donor in their extended family and in unrelated donor registries⁵.

An effective way to overcome these hurdles is to opt for early HLA typing and save critical time. We now get to the point where we tell you how it helps.

Clinical Relevance Of Early HLA Typing

For patients who are newly diagnosed with a condition for which allogeneic hematopoietic stem cell transplantation (HSCT) may be indicated, (human leukocyte antigen) HLA typing along with cytogenetic testing is critical at the time of diagnosis. This allows the process for finding a related or unrelated donor to begin as early as possible, even before your patient has a transplant consultation.

Studies on HSCT have revealed that patients who receive transplants in earlier disease stages have better outcomes than those transplanted in more advanced disease stages6. The researchers used a disciplined, organized process for early HLA typing and cytogenetic testing, rapid donor identification, and early referral for HSCT. The American Society of Clinical Oncology published the results of a study involving high-risk patients with acute myeloid leukemia (AML), a type of blood cancer. In this study, expedited HLA typing was carried out for all high-risk patients at the time of diagnosis⁶.

Early HLA typing allowed for earlier initiation of donor identification and referral for HSCT consultation which helped in⁶

1. Overall improved survival of the patients who underwent transplantation.
2. Improved transplant rate of complete remission.
3. Better recovery outcomes for patients with poor prognosis by initiating the process to find family members or unrelated donors at the time of diagnosis⁷
4. Root down ethnic compatibility in HLA type as an intuitive find for a donor stem cell match⁶

The study also concluded that better outcomes may also be achieved in AML patients with poor prognosis by initiating the process to find family members or unrelated donors at the time of diagnosis⁴.

Early HLA typing can increase the likelihood of a patient undergoing a transplant at the optimal time. This allows the process for finding a related or unrelated donor to begin as early as possible, even before your patient has a transplant consultation.

Summing Up!

By now, we’ve understood that getting an early HLA typing helps in tackling the hurdles of finding the right match while allowing enough time for both clinicians and families to plan, prepare and support a speedy recovery. While an early HLA typing can give you the much-needed breather.

LifeCell offers its exclusive HLA typing service, StemMatch, to its enrolled community banking members. StemMatch helps in determining beforehand the exact number of 6/8, 7/ 8, and 8/8 matching stem cell units available in LifeCell’s registry. LifeCell’s registry consists of over 60,000 qualified & consented cord blood units that are readily available for allogeneic stem cell transplantations. The large registry improves your chances of finding an acceptable match for an Indian patient drastically to >97%! Thus making this a win-win situation for all!

What’s more? You can use this service for your family members too. A comprehensive report is shared by LifeCell within 15 days along with an updated annual status based on new samples added in or retrieved from the registry with no additional cost.

Why wait when this opportunity is knocking at your door? You’ve already made one important decision of banking your baby’s cord blood with LifeCell’s community stem cell banking program. Now make another by signing up for StemMatch, which may, some day, prove to be yours and your family’s proverbial ‘parachute’!