Minimal Residual Disease in Ovarian Biopsies Collected in Patients with Bone Marrow Complete Remission of Acute Lymphoblastic Leukemia
Authors: Chevillon Florian , Dalle Jean-Hugues , Arfeuille Chloé , Chalas Céline , Passet Marie , Drouineaud Véronique , Nguyen Stephanie , Rahal Ilhem , Peffault De Latour Regis , Degaud Michael , Alcantara Marion , Cabannes-Hamy Aurelie , Boissel Nicolas , Clappier Emmanuelle , Poirot Catherine , Dhedin Nathalie 
Published: October 2019

Abstract

The last three authors contributed equally to this work.
Introduction:
Allogeneic hematopoietic stem cell transplantation (HSCT) may improve long-term survival of patients with acute lymphoblastic leukemia (ALL) at high risk of relapse. However, ovarian failure is observed in 70 to 90% of patients who received myeloablative HSCT. Autotransplantation of cryopreserved ovarian cortex harvested before gonadotoxic treatments has been shown to re-establish the menstrual cycles and lead to the birth of healthy children (Donnez J. N Engl J Med, 2018). In patients treated for acute leukemia, concern has been expressed about the risk of leukemia recurrence after the ovarian autotransplantation due to the potential presence of residual leukemic cells in the ovarian tissue (Dolmans MM. Blood, 2010). To date, there were only few studies evaluating the presence of leukemic cells in cryopreserved ovarian tissue, and in most cases ovarian tissues were harvested at diagnosis of ALL or early after onset of chemotherapy. The present study prospectively investigated, in the context of fertility preservation, the presence of leukemic cells in cryopreserved ovarian samples harvested before allogeneic HSCT in patients in complete remission (CR) of ALL.
Patients and Methods:
From October 2015 to May 2018, all female patients with ALL who had a leukemia specific marker and underwent ovarian cryopreservation before allogeneic HSCT as part of preservation fertility program in 3 centers were included in the study. Consents were obtained from the guardians and/or age appropriate patients. The specific local ethical committees approved the study. Ovariectomy was performed after patients achieved CR, mostly in the weeks preceding HSCT. Ovarian cortex was separated into several fragments and cryopreserved as previously described (Poirot C. Human Reprod, 2002). When more than 14 cortical fragments were obtained, one was dedicated to molecular analysis, as well as the ovarian medulla. MRD quantification was performed by quantitative PCR of clonal rearrangements of immunoglobulin/T-cell receptor genes (Ig/TCR) or oncogenic fusion genes, according to EuroMRD and European Against Cancer (EAC) guidelines. MRD in ovarian samples were compared to MRD in bone marrow (BM) sample obtained at the same time point.
Results:
Fourteen patients were included in the study: 12 with B-cell precursor ALL, 1 with T-cell ALL and 1 with mixed phenotype acute leukemia. MRD marker was Ig/TCR rearrangement in 12 cases, M-BCR-ABL transcript in 1 case and genomic MLL-AF4 in 1 case. Median age at transplant was 18.2 years (range 1.1 - 35.2 years). Criteria for HSCT were poor early response to treatment (N=8), Philadelphia positive ALL (N=1), or previous relapse (N=5). With a median follow-up after HSCT of 8.1 months (range 0.8 - 29.8 months), all patients are disease-free.
At the time of ovariectomy, 7/14 (50%) patients had undetectable MRD in ovarian samples, 6 had low positivity below 10-4 and one had positive MRD higher than 10-4. Unexpectedly of the 7 patients with positive ovarian MRD, 4 were undetectable in BM. One of the 7 patients with undetectable MRD in ovarian samples was positive in bone marrow. Concordant results were observed between the cortex and medulla samples in 10 of the 11 cases where both could be tested.
Conclusions:
To our knowledge, this series is the largest cohort evaluating MRD in ovarian samples from patients with ALL in complete remission after full chemotherapy regimen. We detected low levels of residual leukemic cells in ovarian tissues in half of the patients, some of them having no detectable MRD in BM at the time of ovariectomy, suggesting that leukemic cells could preferentially persist in ovary. Our results warrant further analyses of an extended cohort and longer post-transplant follow-up to better assess the potential presence of leukemic cells in ovarian samples and evaluate the impact of ovarian MRD status on post HSCT relapse. Still, autotransplantation of cryopreserved ovarian cortex could be discussed after allogeneic HSCT in patients with undetectable ovarian MRD.
Table 1. MRD evaluation in bone marrow and ovarian samples.
BM, bone marrow; BCP-ALL, B-cell precursor ALL; Ph-positive ALL, ALL with Philadelphia chromosome; NA: not available. Undetectable MRD means negative result obtained with a sensitivity of 10-4 or 10-5. BCR-ABL1 MRD results are expressed as the BCR-ABL1/ABL1 transcripts ratio.

Disclosures
No relevant conflicts of interest to declare.