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mutations/megabase; P¼0.004) than those in the PD-L1 TPS <1% group. Tumors in the PD-L1 TPS 90% group were more likely to have KRAS (47.3% vs 31.3%; P¼0.002), MET exon 14 (9.6% vs 2.1%; P¼0.003), and TP53 mutations (71.0% vs 49.7%; P<0.001) than those in the PD-L1 TPS <1% group. Compared to the PD-L1 TPS 90% group, the PD-L1 TPS <1% group was more likely to have EGFR (23.6% vs 8.2%; P<0.001) and STK11 (23.4% vs 5.0%; P<0.001) mutations, as well as the absence of known oncogenic driver mutations (35.2% vs 24.8%; P¼0.04). Chromosomal gain alterations (amplification or copy number gain) of the 9p24.1 locus, where the PD-L1, PD-L2, and JAK2 genes are located, were more common in the PD-L1 TPS 90% group than in the PD-L1 TPS <1% group (11.4% vs 2.8%, respectively; P<0.001). Chromosomal loss alterations (copy loss or deletion) of the 9p24.1 locus were more common in the PD-L1 TPS <1% than in the PD-L1 TPS 90% group (27.5% vs 3.8%, respectively; P<0.001). A repeated biopsy case showed acquired loss PD-L1 expression (PD-L1 TPS changed from 90% to 0%) with concomitant acquired loss of the 9p24.1 locus. Conclusion: High PD-L1 expression in NSCLC is associated with tobacco use, high TMB, gain of the 9p24.1 locus and mutations in KRAS, MET exon 14, and TP53. PD-L1 negativity is associated with never smoking status, low TMB, loss of the 9p24.1 locus, mutations in EGFR and STK11, and the absence of oncogenic driver mutations.

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15035 Background: Platinum and doxorubicin have different mechanisms of action, show no cross-resistance, and their toxicities do not overlap. Because pegylated liposomaI doxorubicin (Lipo-Dox was manufactured by TTY Biopharm Company Ltd. in Taiwan) appears to be a promising form of delivering doxorubicin with decrease of some of the most problematic toxicities, a combination with platinum should be assessed. Methods: An open-label, non-comparative, single center phase II clinical trial. Eligible patients must have histologically proven advance ovarian cancer with two-dimensioned measurable disease or evaluable disease (defined as CA-125 ≥ 40 U/ml), who have been treated with one or two previous platinum- and taxane-based regimen. All patients will hospitalize for 24 hours for treatment. The dose of platinum is fixed (cisplatin at 75 mg/m2 or carboplatin at AUC=5) on D1 and the initial dose of pegylated liposomaI doxorubicin (Lipo-Dox) is 35 mg/m2 on D2 at a 4-week interval. Results: Twenty patients were enrolled from July 2002 to January 2004 and follow up until June 2004. All eligible patients are assessable for response and toxicity. The overall response rate was 80%. Of the 20 patients eligible for response evaluation, 10 (50%) patients had a complete response, 6 (30%) had partial response, 3 (15%) were with stable disease, and 1 (5%) showed progressive disease. An overall response (OR) was achieved in 80% of patients. In patients achieving an OR based on WHO criteria, median CA125 levels declined from 142 U/ml (range, 13–3670 U/ml) during the baseline to 26.5 U/ml (range, 5–375 U/ml) during the last cycle. Median time to response was 65 days (range, 12–188 days). Median duration of response was 471 days (range 146–1085 days). Furthermore, the median time to progression was 481 days (range, 138–1136 days). The main toxicity was myelosuppression, with grade 3 and 4 neutropenia in 3 patients, anemia in 4 patients, and leukopenia in 2 patients. Conclusions: Based on effectiveness and toxicity advantages, the combination of pegylated liposomaI doxorubicin (Lipo-Dox) and platinum should be considered in patients with advanced ovarian cancer in late relapse. No significant financial relationships to disclose.

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