Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL)

Ph+ ALL is found the same way as other kinds of ALL. Tests usually start with a complete blood count (CBC) and a blood smear, a look at the blood under a microscope. The care team then takes a small sample of bone marrow (a bone marrow aspiration and biopsy) to confirm acute leukemia.

A lab test called flow cytometry (immunophenotyping) shows which kind of young white blood cell the leukemia comes from, usually a B cell. Chromosome tests (cytogenetics) and gene tests called FISH and RT-PCR then look for the BCR::ABL1 joined gene. The National Cancer Institute's summary for doctors says B-cell ALL should be checked for it.

A spinal tap (lumbar puncture) checks the spinal fluid for leukemia, and a chest x-ray, CT or MRI may be done. For adults with ALL (age 40 and older in their guidelines), NMDP and ASTCT also advise tissue typing (HLA typing) at diagnosis. That way a donor search can start quickly if one is needed.

Treatment pairs a daily TKI pill, such as imatinib, dasatinib or ponatinib, with other leukemia treatment. That may be chemotherapy, or a newer plan that pairs the TKI with blinatumomab and steroids and uses little or no standard chemotherapy. Blinatumomab is an immune medicine that helps T cells find and attack B-cell leukemia. Age, overall health and how the leukemia responds shape the plan.

Doctors track measurable residual disease (MRD), the tiny amount of leukemia that only very sensitive lab tests can find. For many years, a donor stem cell transplant in first remission was the usual plan for adults who could have one. Today, studies suggest that some adults whose MRD tests turn negative early on modern TKI and immune-based plans may be able to avoid one. Transplant is still favored when MRD stays positive, when a resistant gene change appears or after relapse. Children who respond well early to a TKI plus chemotherapy are no longer routinely advised to have a transplant.

In the United States, ponatinib received accelerated approval in March 2024 for adults with newly diagnosed Ph+ ALL, given with chemotherapy, which means more trial results are still required. Blinatumomab is approved there for B-ALL that has relapsed, has not responded to treatment or leaves MRD behind. Its approval as part of first treatment covers only Philadelphia-negative B-ALL, so its use in first treatment of Ph+ ALL comes mainly from clinical studies. Both carry boxed warnings: ponatinib for blocked arteries, blood clots, heart failure and liver damage, and blinatumomab for cytokine release syndrome, a strong body-wide inflammatory reaction, and for nervous system side effects. If the leukemia comes back, options can include a different TKI, inotuzumab (an antibody that carries a cell-killing drug to the leukemia cells), blinatumomab, CAR-T therapy or a transplant. Not every one of these medicines is available or covered in every country.

When a transplant from a donor is planned, the team usually tests brothers and sisters first. Each full sibling has about a one in four chance of being a full match.

Most patients do not have a matched relative. In the words of NMDP, the U.S. registry, “75% of patients don’t have a fully matched donor in their own family.” The team then searches registries of volunteer donors around the world and banks of donated cord blood. In some transplants, a half-matched parent, child or sibling can also be the donor.

Matching depends on inherited tissue markers called HLA, so a patient is most likely to match someone who shares their ancestry. Every person who joins makes the search a little more likely to succeed, especially for patients from groups that are underrepresented on registries.

Ph+ ALL used to be one of the hardest leukemias to treat. Before targeted pills, it was rarely cured with chemotherapy alone. TKIs changed that, and long-term survival is now routinely reported. Newer plans that pair a TKI with the immune medicine blinatumomab have shown high survival in trials, though longer follow-up is still being collected.

Several things shape the outlook. They include age, the white blood cell count at diagnosis, extra gene changes such as IKZF1 deletions, and how deeply the leukemia responds. In one Italian trial of adults, no relapses or deaths had occurred among people with an early deep response in gene tests (an early molecular response). Which factors matter most can differ from one treatment plan to another.