Author of

• 29533

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  JCSE01 - Joint IASLC-CSCO-CAALC Session (ID 63)

  • Event: WCLC 2019
  • Type: Joint IASLC-CSCO-CAALC Session
  • Track:
  • Presentations: 1
  • Moderators:Chunxue Bai, Tony Mok, Yi-Long Wu, Qing Zhou, Nan Wu
  • Coordinates: 9/07/2019, 07:00 - 11:15, Toronto (1985)

  • 29556

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    JCSE01.23 - Specific TP53 Mutation Subtypes as Biomarker for Response to PD-1/L1 Blockade Immunotherapy in NSCLC (ID 3437)

    07:00 - 11:15  |  Author(s): Jiao Jiao Huan
    • Abstract
    • Slides

    Abstract
    Background
    Although TP53 co-mutation with KRAS have been proved to have predictive value for response to PD-1/L1 blockades, not all TP53 mutations are equal in this context. TP53 subtypes as independent factors to predict the response to PD-1/L1 blockade have not yet reported.
    
    Methods
    We performed an integrated analysis on the multiple-dimensional data types including genomic and clinical data from cohorts of NSCLC public (240 from MSK database) and local databases (224 patient with PD-L1 IHC score, 1986 NSCLC with TMB data). Durable clinical benefit (DCB) was defined as partial response/stable disease that lasted more than 6 months.
    
    Results
    The presence of mutant TP53 was associated with longer median progression free survival (mPFS) in NSCLC taking PD-1/L1 blockade therapy compared with TP53 wild-type group in the MSK-cohort (4.3 vs2.6 months, P=0.0027, HR=0.6409, 95%CI, 0.49 to 0.88). TP53 frameshift seemed to predict longer mPFS (6.6 months, P=0.0159, HR= 0.41, 95%CI, 0.26 to 0.65) than TP53 wild-type, TP53 missense (mPFS=4.27 months, P=0.17) and TP53 nonsense status (mPFS=2.7 months, P=0.002).NSCLC with TP53 frameshift mutation had a 52.9% rate of DCB, which was higher than TP53 missense (34.4%) and nonsense (21.1%) group. Besides, in the MSK cohort, five of six patients with TP53 truncated mutation in proline-rich (PR) domain (residues 58--101) achieved DCB, and one patient achieved 5.5 months of PFS and did not progress. Fractions of PD-L1 low-positive (1% - 49%) and PD-L1 high-positive (≥50%) tumors between each TP53 mutation subtype and wild-type groups are analyzed based on local data. The TP53 mutation rate was significantly higher in NSCLC with PD-L1 score >50% (P=0.004). But NSCLC with TP53 frameshift showed lower fractions of PD-L1 high-positive (12.5%, 2/16) compared with TP53 missense group (27.5%, 33/120) and TP53 nonsense group (25.8%, 8/31). PD-L1 low-positive rate is also lower in TP53 frameshift group (25.0%, 4/16) than TP53 missense (30.8%, 37/120) and nonsense group (29.0%, 9/31). Among 1986 NSCLC patients with TMB data, each TP53 mutation subtype is associated with significantly higher TMB than TP53 wildtype, especially among NSCLC with TP53 truncated mutation in PR domain (median TMB= 9 mut/Mbs). But no significant difference was found between TP53 mutation subtypes in TMB.

    
    
    Conclusion
    ​​​​​​​Our study demonstrated heterogeneity among TP53 mutations in predicting the response to PD-1/L1 blockade therapy. TP53 frameshift mutation may contribute to better PD-1/L1 blockade therapy response beyond PD-1/L1 IHC status. And the truncated TP53 mutation in PR domain may contribute to DCB.

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