Ex Vivo Drug Profiling Reveals Dasatinib Sensitivity in p53-Aberrant Refractory Lymphoid Malignancies
Key Insights
A functional precision medicine study demonstrates that ex vivo drug sensitivity and resistance testing (DSRT) is feasible in patients with relapsed/refractory non-Hodgkin lymphoma and acute lymphoblastic leukemia (search).
Hierarchical clustering identified a grouping of p53-aberrant samples, with significantly higher sensitivity to dasatinib compared to p53 wild-type disease (median sDSS 14.17 vs −2.6, P = 0.0003).
Commonly used chemotherapeutic agents including platinum compounds, nucleoside analogues, and anthracyclines showed low selective drug sensitivity scores, consistent with a heavily pretreated cohort.
A prospective observational study from Karolinska University Hospital (search) has demonstrated that ex vivo drug sensitivity and resistance testing (DSRT) can identify actionable therapeutic vulnerabilities in patients with relapsed/refractory (R/R) lymphoid malignancies, including a striking association between p53 aberrations and sensitivity to the tyrosine kinase inhibitor dasatinib.
The Drug Sensitivity Assay – Lymphoma/Leukemia (DSA-LL) study enrolled 26 adult patients with R/R lymphoid malignancies, with one participant sampled at two different relapses, yielding 27 samples for analysis. Diagnoses spanned aggressive B-cell and T-cell lymphomas, including diffuse large B-cell lymphoma (search) (DLBCL), peripheral T-cell lymphoma (search) (PTCL), mantle cell lymphoma (search) (MCL), and acute lymphoblastic leukemia (search) (ALL). Samples were obtained from various anatomical sites, and up to 528 clinically approved and investigational drug conditions were tested at five concentration points across a 10⁴-fold concentration range.
Feasibility in a Heavily Pretreated Population
Of the 27 samples collected, three were excluded from analysis due to insufficient mononuclear cell (MNC) yield, all of which were core needle biopsies. Cell viability was not a primary cause for exclusion, with a median viability of 99% (range 25–100%). A 24-hour incubation period was employed both to maintain lymphoma cell viability ex vivo and to ensure a short turnaround time essential for clinical implementation in this patient population, where treatment must proceed without delay.
The study found that ex vivo DSRT is feasible in R/R non-Hodgkin lymphoma and ALL, particularly in patients with leukemic disease, bone marrow involvement, or nodal disease. Feasibility was limited in patients with exclusively solid organ involvement, though the sample size was small and further testing is warranted.
Chemotherapy Resistance and BCL-2 (search) Inhibitor Sensitivity
Ex vivo drug profiling demonstrated low selective drug sensitivity scores (sDSS) for commonly used chemotherapeutic agents. Platinum compounds (oxaliplatin median sDSS −6.08, carboplatin median sDSS −3.77), nucleoside analogues (cytarabine median sDSS −6.99, fludarabine median sDSS −8.45), etoposide (median sDSS −2.01), and anthracyclines (doxorubicin median sDSS −6, epirubicin median sDSS −6.36) all showed substantially lower activity compared to healthy bone marrow controls. This pattern aligns with expectations for a cohort with extensive prior treatment, where the median number of prior therapies was four.
In contrast, BCL-2 (search) family inhibitors exhibited a range of sensitivities. Venetoclax showed a median sDSS of 2.2 (range −5.1–24.2), while the BCL-2/BCL-xL inhibitor navitoclax demonstrated the most consistent sensitivity across the cohort, with a median sDSS of 10.0 (range −8.5–22.7). Glucocorticoids such as dexamethasone also displayed variable activity (median sDSS 2.8, range −2.5–21.6). The authors note that clinical responses to BCL-2 inhibitors have previously been reported in relapsed ALL, particularly T-ALL, and MCL, and that the success of the venetoclax-based ViPOR regimen in relapsed DLBCL supports the clinical relevance of these findings.
p53-Aberrant Disease and Dasatinib Sensitivity
Hierarchical clustering analysis revealed a grouping of p53-aberrant samples, defined by TP53 mutation, del(17p), or p53 overexpression. When comparing p53-aberrant disease to p53 wild-type (WT) disease, the researchers observed significantly higher sDSS for dasatinib in the aberrant group (median sDSS 14.17 vs −2.6, P = 0.0003, q = 0.162784). All p53-aberrant cases demonstrated sensitivity to dasatinib, compared to only one p53-WT case.
Further analysis of ABL and SRC inhibitors identified three additional compounds with increased activity in p53-aberrant versus p53-WT samples: saracatinib, an SRC and ABL inhibitor (median sDSS 5.4 vs −1.72, P = 0.025372, q = 0.115614); bosutinib, both an ABL and SRC inhibitor (median sDSS 3.75 vs −3.94, P = 0.028617, q = 0.131555); and ponatinib, an ABL inhibitor (median sDSS 3.6 vs −3.68, P = 0.043417, q = 0.131555).
Sensitivity to dasatinib in p53-aberrant disease has been previously reported in chronic lymphocytic leukemia (search). However, the DSA-LL findings suggest this vulnerability may extend across multiple diagnoses in p53-aberrant R/R lymphoid malignancies. To explore this further, the investigators leveraged publicly available data from the BEAT-AML trial and the DepMap cancer cell line database. In BEAT-AML, p53 mutation was associated with decreased sensitivity to dasatinib in AML patients, and no significant association between p53 mutation status and dasatinib sensitivity was observed across all cancer cell lines or specifically in lymphoid cell lines.
Additionally, a trend toward increased sensitivity to PI3K inhibitors was observed in p53-aberrant disease, including idelalisib (median sDSS 13.62 vs −2.16, P = 0.0009, q = 0.162784), serabelisib (median sDSS 4 vs −1.54, P = 0.006, q = 0.300380), and omipalisib (median sDSS 9.4 vs −5.75, P = 0.026, q = 0.368484), though this was not consistent across all PI3K inhibitors tested.
Limitations and Future Directions
The authors acknowledge several limitations. The method required a large number of MNCs, limiting applicability in Hodgkin lymphoma, primary CNS lymphoma, and patients with limited disease burden. Reducing the number of compounds tested could improve feasibility in these contexts, though this would restrict drug repurposing opportunities. The limited efficacy of conventional chemotherapeutic agents in the assay requires further investigation, as the short 24-hour incubation may disproportionately disadvantage these agents.
Comprehensive mutational profiling beyond p53 status was not available for the current cohort. The mechanistic basis for dasatinib sensitivity in p53-aberrant disease remains unclear, as ABL inhibition, SRC inhibition, combined target engagement, or off-target effects cannot be distinguished within this dataset. Clinical outcome and treatment response data are being prospectively collected, and future studies will evaluate their correlation with ex vivo DSRT profiles. Larger, prospectively designed studies in heavily pretreated R/R patients will be required to define the contributing mechanisms and establish the therapeutic relevance of this association.