Mytomicin-C, Metronomic Capecitabine, and Bevacizumab in Patients With Unresectable or Relapsed Pseudomyxoma Peritonei of Appendiceal Origin.

INTRODUCTION: Pseudomyxoma peritonei (PMP) is a rare, slow growing tumor, traditionally considered chemoresistant. The only curative approach is cytoreductive surgery (CRS) followed by hyperthermic intraperitoneal chemotherapy (HIPEC). At disease relapse, or in patients with inoperable disease at diagnosis, no standard treatment has been defined, though nonrandomized series showed promising results with fluoropyrimidine-based regimens. PATIENTS AND METHODS: We conducted a prospective study in patients with relapsed or unresectable PMP and confirmed disease progression at baseline. Patients received MMC (7 mg/m2 every 6 weeks, up to a maximum of 4 cycles) plus metronomic capecitabine (625 mg/sqm/day b.i.d.) and bevacizumab (7.5 mg/kg every 3 weeks) until disease progression, unacceptable toxicity, or consent withdrawal. Primary endpoint was progression-free survival (PFS); secondary endpoints were overall survival (OS), overall response rate according to RECIST v1.1 criteria, serum markers response and safety. RESULTS: Fifteen patients were included. At a median follow-up of 26.1 months (IQR, 17.7-49.6), median PFS was 17.9 months (95% CI, 11.0-NE), with 1-year PFS and OS rates of 73% and 87%. Safety profile was manageable, with only 13% G3/G4 treatment-related adverse events. CONCLUSION: Metronomic capecitabine, bevacizumab, and MMC are an active regimen in advanced and progressive PMP and favorably compares with historical series.

Prognostic and Predictive Value of Microsatellite Instability, Inflammatory Reaction and PD-L1 in Gastric Cancer Patients Treated with Either Adjuvant 5-FU/LV or Sequential FOLFIRI Followed by Cisplatin and Docetaxel: A Translational Analysis from the ITACA-S Trial.

BACKGROUND: Patients with high microsatellite instability (MSI) gastric cancer (GC) show improved survival and no benefit or harm from adjuvant and/or perioperative chemotherapy. The role of immune microenvironment in GC is largely unknown. MATERIALS AND METHODS: In the present study, 256 tumor tissue blocks were centrally collected from patients enrolled in ITACA-S, a randomized adjuvant trial of 5-FU/LV versus sequential FOLFIRI and cisplatin-docetaxel. MSI status was assessed by multiplex PCR, inflammatory reaction by H&E morphological assessment, and programmed death-ligand 1 (PD-L1) expression by immunohistochemistry. RESULTS: Overall, 9% patients had MSI-high tumors, 23% had high inflammatory reaction, 11% had tumor PD-L1 ≥ 1%, and 11% had stromal PD-L1 ≥ 1%. A significant association with disease-free survival (DFS) and overall survival (OS) was found for MSI-high (hazard ratio [HR], 0.43; p = .02; HR, 0.40; p = .02) and high inflammatory reaction (HR, 0.55; p = .010; HR, 0.53; p = .008) but not for PD-L1. At multivariable analysis, only MSI showed an independent association with both DFS (p = .02) and OS (p = .01), whereas inflammatory reaction showed an independent association only with OS (p = .04). Patients with tumor PD-L1 ≥ 1% had a significantly longer DFS in sequential chemotherapy than in than 5-FU/LV arm (interaction p = .04) and a trend for OS (interaction p = .12). CONCLUSION: Our data suggest that MSI status could be a useful prognostic biomarker in patients with radically resected stage II-III GC and should be used as stratification factor in future trials. Tumor PD-L1 ≥ 1% should be further investigated as a potential predictor of benefit from intensive chemotherapy. IMPLICATIONS FOR PRACTICE: In this post hoc analysis of patients with radically resected gastric cancer randomized to an intensive sequential chemotherapy regimen versus 5-FU/LV monotherapy as adjuvant treatment in the ITACA-S trial, MSI-high status was independently associated with better disease-free survival and overall survival (OS) and inflammatory reaction was independently associated with better OS. Moreover, tumor PD-L1 expression ≥1% was associated with greater benefit from intensive sequential chemotherapy compared with 5-fluorouracil plus leucovorin (5-FU/LV), whereas PD-L1 expression <1% was not, conditioning a statistically significant interaction between such biomarker and treatment arms. The meta-analysis of individual patients' data from available studies could yield data on the role of MSI status that could inform clinical decisions.

Atypical RAS Mutations in Metastatic Colorectal Cancer.

PURPOSE: To describe the clinical and molecular features of metastatic colorectal cancers (mCRCs) bearing uncommon atypical RAS (At-RAS) mutations at codons other than 12, 13, 59, 61, 117, and 146. MATERIALS AND METHODS: By exploiting five next-generation sequencing sources (Italian collaboration, Memorial Sloan Kettering Cancer Center, Samsung Medical Center, the Biomarker Research for Anti-EGFR Monoclonal Antibodies by Comprehensive Cancer Genomics (BREAC) study, and the Foundation Medicine database), we retrieved 175 At-RAS mutated cases. Molecular data were obtained from 163 samples from Memorial Sloan Kettering Cancer Center and the Foundation Medicine database. Clinical data were available for 27 At-RAS-positive and 467 negative cases from the Italian collaboration, Memorial Sloan Kettering Cancer Center, Samsung Medical Center, and the BREAC study. RESULTS: At-RAS mutations were identified in 163 (0.9%) of 18,270 mCRCs. Among 133 with evaluable microsatellite instability status, 11 (8%) were microsatellite instability high. POLE exonuclease domain mutations had higher frequency (7%) than expected and were found only in microsatellite-stable tumors with high tumor mutational burden (TMB). Overall, 17% (28 of 163) of At-RAS cases had TMB greater than 20 mutations/Mb. Co-occurring typical RAS/BRAF V600E mutations and NF1 mutations, presumed to cause RAS activation, were found in 30% and 12% of samples, respectively (up to 43% and 50%, respectively, in TMB-high samples). Patients with RAS/BRAF wild-type mCRC achieved a median overall survival (OS) of 42.1 months, whereas those harboring isolated At-RAS, typical RAS, or BRAF V600E mutations showed a median OS of 32.3, 30.0, and 17.9 months, respectively (P < .001). No significant OS difference (P = .240) was found between patients with At-RAS versus typical RAS-mutated mCRC. Only one of six patients evaluable for primary resistance to anti-epidermal growth factor receptors achieved tumor response. CONCLUSION: At-RAS mutations may be a marker for RAS pathway activation and can be associated with high co-occurrence of POLE exonuclease domain mutations.