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Marianne Ratcliffe
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EX04 - Mini Oral Abstract Session - MA08.06, MA18.02, MA19.02, MA20.11 (ID 1006)
- Event: WCLC 2018
- Type: Exhibit Showcase
- Track: Advanced NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 9/26/2018, 09:55 - 10:25, Exhibit Showcase Theater
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EX04.03 - Prior Therapy and Increased Expression of PD-L1 in NSCLC Tumor Samples (ID 11881)
10:05 - 10:10 | Author(s): Marianne Ratcliffe
- Abstract
Background
Tumor PD-L1 expression has been shown to enrich for response to immunotherapy in several indications, including advanced NSCLC. However, the stability of PD-L1 expression over time and its relationship with non-immunotherapy cancer treatment is currently uncertain. We hypothesized that prior chemotherapy or radiotherapy would increase PD-L1 expression.
a9ded1e5ce5d75814730bb4caaf49419 Method
In the Phase 2, open-label, single-arm durvalumab ATLANTIC study (NCT02087423), patients who had received ≥2 prior systemic regimens in the treatment of Stage IIIB or IV NSCLC were screened for tumor PD-L1 expression by immunohistochemistry using the VENTANA PD-L1 (SP263) Assay (25% tumor cell [TC] cutoff). PD-L1 expression was assessed using either a recent (<3 months) or archival sample; a subset of patients provided both. The relationship between non-immunotherapy cancer treatment and prevalence of tumor PD-L1 expression ≥25% (TC≥25%) was assessed in patients who received therapy prior to sample acquisition versus those who did not. Pearson’s chi-squared test was used to examine the differences between patient subgroups.
4c3880bb027f159e801041b1021e88e8 Result
Of the patients screened for participation in ATLANTIC, 1590 were successfully assessed for PD-L1 expression. PD-L1 TC≥25% prevalence was higher in patients who had received prior radiotherapy or chemotherapy before sample acquisition, with prevalence noticeably higher in those who had received ≥2 lines of prior chemotherapy. Prior EGFR inhibitor treatment did not have any noticeable relationship to TC≥25% prevalence (Table). In the subset of patients with paired recent and archival samples, TC≥25% prevalence remained the same in 74% of cases, increased over time in 19.5%, and decreased in 6.5%.
8eea62084ca7e541d918e823422bd82e ConclusionTreatment regimen
Subgroup (n)
PD-L1 TC≥25% prevalence (%)
P-value
Prior tyrosine kinase inhibitor (TKI)
No prior TKI (607)
39.9
0.947
Prior TKI (411)
39.7
Prior EGFR inhibitor (379)
38.5
0.154
Prior ALK inhibitor (15)
60.0
Prior chemotherapy
No prior chemotherapy (145)
29.0
0.004
Prior chemotherapy (873)
41.6
Number of lines of prior chemotherapy
0 (155)
29.0
0.031
1 (10)
30.0
2 (138)
42.8
>2 (725)
41.5
Prior radiotherapy
No prior radiotherapy (599)
37.1
0.034
Prior radiotherapy (419)
43.7
PD-L1 expression may increase in response to chemotherapy or radiotherapy and is unlikely to decrease over time. Re-biopsy may provide a more accurate assessment of current tumor PD-L1 expression status when a low/negative result is seen in an archival sample, particularly if the patient has received multiple lines of intervening radiotherapy or chemotherapy.
6f8b794f3246b0c1e1780bb4d4d5dc53
