Enhanced tumor response to radiotherapy after PD-1 blockade in metastatic gastric cancer

BACKGROUND

Immune checkpoint inhibitors may enhance the efficacy of radiotherapy (RT) in cancer treatment but the effect remains unknown in metastatic gastric cancer (mGC). This study aimed to compare the tumor shrinkage by palliative RT for mGC patients with or without previous exposure to anti-PD-1 therapy.

METHODS

Data of 36 mGC patients who had received palliative RT from April 2013 to May 2019 were analyzed. Primary tumor responses were evaluated through a volumetric measurement-based method using computed tomography (CT) and endoscopic responses were evaluated in patients who underwent endoscopy before and after RT. Tumor microenvironment (TME) immune status was investigated by analyzing tumor-infiltrating lymphocytes by flow cytometry.

RESULTS

Among 36 patients, 18 had previous exposure to anti-PD-1 before RT showing no significant differences in baseline characteristics with the other 18 patients without exposure to anti-PD-1 treatment. Tumor responses were observed in 28% (5/18) and none (0/18) in the anti-PD-1-exposed vs. naïve group, respectively (P = 0.045). Five out of eight patients in the anti-PD-1-exposed group, who underwent endoscopy after RT showed partial response, but none in the anti-PD-1-naïve patients showed response (P = 0.026). Increase in the CD8⁺ T cell/effector regulatory T cell ratio in TILs after anti-PD-1 therapy was noted in three responders to RT, but not in the other three non-responders.

CONCLUSIONS

Prior exposure to anti-PD-1 therapy increases tumor response to RT. Immune profiling suggests that anti-PD-1 therapy may enhance the efficacy of RT by immunoactivation in the TME.

Safety of pembrolizumab in recurrent or advanced gastric cancer expressing PD-L1 refractory to platinum and fluoropyrimidine

INTRODUCTION

Pembrolizumab is a highly selective fully human immunoglobulin 4 monoclonal antibody against programmed death 1 (PD-1). Phase II and III trials have demonstrated that pembrolizumab has antitumor activity in previously treated patients with advanced gastric cancer (AGC).

AREA COVERED

Pembrolizumab was approved by the US Food and Drug Administration in September 2017 as third-line or later treatment of AGC in patients positive for programmed death ligand 1 (PD-L1). In this article, we review the development of pembrolizumab, its pharmacology, and its safety profile as monotherapy in patients with PD-L1 positive previous treated AGC.

EXPERT OPINION

Pembrolizumab has demonstrated durable response and acceptable safety profile in patients receiving two previous courses of systemic chemotherapy. It has become a treatment option in patients with AGC. Currently, there are several ongoing clinical trials of pembrolizumab in combination with cytotoxic chemotherapy or molecular targeting agents AGC.

Multicenter Phase I/II Trial of Napabucasin and Pembrolizumab in Patients with Metastatic Colorectal Cancer (EPOC1503/SCOOP Trial)

PURPOSE

This is a phase I/II trial to assess the efficacy and safety of napabucasin plus pembrolizumab for metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

Phase I was conducted to determine the recommended phase 2 dose (RP2D) in a dose escalation design of napabucasin (240 to 480 mg twice daily) with 200 mg pembrolizumab every 3 weeks. Phase II included cohort A (n = 10, microsatellite instability high, MSI-H) and cohort B (n = 40, microsatellite stable, MSS). The primary endpoint was immune-related objective response rate (irORR). PD-L1 combined positive score (CPS), genomic profiles, and the consensus molecular subtypes (CMS) of colorectal cancer were assessed.

RESULTS

A total of 55 patients were enrolled in this study. In phase I, no patients experienced dose-limiting toxicities, and napabucasin 480 mg was determined as RP2D. The irORR was 50.0% in cohort A and 10.0% in cohort B. In cohort B, the irORR was 0%, 5.3%, and 42.9% in CPS < 1, 1≤ CPS <10, and CPS ≥ 10, respectively. Patients with objective response tended to have higher tumor mutation burden than those without. Of evaluable 18 patients for CMS classification in cohort B, the irORR was 33.3%, 0%, 33.3%, and 33.3% in CMS1, CMS2, CMS3, and CMS4, respectively. The common grade 3 or higher treatment-related adverse events included fever (10.0%) in cohort A and decreased appetite (7.5%) and diarrhea (5.0%) in cohort B.

CONCLUSIONS

Napabucasin with pembrolizumab showed antitumor activity with acceptable toxicities for patients with MSS mCRC as well as MSI-H mCRC, although it did not meet the primary end point. The impact of related biomarkers on the efficacy warrants further investigations in the additional cohort.See related commentary by Nusrat, p. 5775.

Clinical and molecular factors for selection of nivolumab or irinotecan as third-line treatment for advanced gastric cancer

BACKGROUND

The use of nivolumab or irinotecan as the third-line treatment for patients with advanced gastric cancer (AGC) remains controversial.

METHODS

This study analyzed patients with AGC treated with nivolumab or irinotecan (nivolumab group or irinotecan group, respectively) from May 2016 to April 2019 following two or more previous lines of chemotherapy. Univariate survival analysis was conducted to identify the clinical and molecular factors associated with progression-free survival (PFS).

RESULTS

A total of 156 patients (74 treated with nivolumab and 82 treated with irinotecan) were analyzed. The median PFS was 1.9 months in both treatment groups. The median overall survival (OS) was 7.2 and 6.2 months in the nivolumab and irinotecan groups, respectively. Eastern Cooperative Oncology Group performance status of 1 or more, liver metastasis, a large tumor size at baseline, and HER2-positive status were associated with a worse PFS in the nivolumab group compared with the irinotecan group. The nivolumab group showed a significantly longer PFS (median 3.1 versus 2.0 months) and OS (median 12.9 versus 7.8 months) than the irinotecan group in patients with 0 or 1 of these factors, whereas the irinotecan group showed a significantly longer PFS (median 1.0 versus 1.8 months) and a trend of longer OS (median 3.9 versus 6.1 months) in patients with ⩾2 of these factors.

CONCLUSIONS

Some clinical and molecular factors were associated with outcomes following nivolumab or irinotecan as the third- or later-line treatment in patients with AGC. These factors must be considered while selecting an optimal treatment option.

An Oncogenic Alteration Creates a Microenvironment that Promotes Tumor Progression by Conferring a Metabolic Advantage to Regulatory T Cells

Only a small percentage of patients afflicted with gastric cancer (GC) respond to immune checkpoint blockade (ICB). To study the mechanisms underlying this resistance, we examined the immune landscape of GC. A subset of these tumors was characterized by high frequencies of regulatory T (Treg) cells and low numbers of effector T cells. Genomic analyses revealed that these tumors bore mutations in RHOA that are known to drive tumor progression. RHOA mutations in cancer cells activated the PI3K-AKT-mTOR signaling pathway, increasing production of free fatty acids that are more effectively consumed by Treg cells than effector T cells. RHOA mutant tumors were resistant to PD-1 blockade but responded to combination of PD-1 blockade with inhibitors of the PI3K pathway or therapies targeting Treg cells. We propose that the metabolic advantage conferred by RHOA mutations enables Treg cell accumulation within GC tumors, generating an immunosuppressive TME that underlies resistance to ICB.

Improved efficacy of taxanes and ramucirumab combination chemotherapy after exposure to anti-PD-1 therapy in advanced gastric cancer

BACKGROUND

The efficacy and safety of chemotherapy (CTx) after anti-PD-1 therapy in patients with advanced gastric cancer (AGC) remains unclear.

METHODS

Medical records of consecutive patients with AGC treated with both CTx (taxanes plus ramucirumab, taxanes monotherapy or irinotecan) and anti-PD-1 therapy from June 2015 to April 2019 were retrospectively analysed. Patients were divided into two groups based on prior exposure to anti-PD-1 therapy: anti-PD-1-exposed and anti-PD-1-naïve groups. CTx-related outcomes were compared between two groups in the overall population and each CTx population.

RESULTS

In total, 233 patients (67 anti-PD-1-exposed, 166 anti-PD-1-naïve) were included. In the overall population, the objective response rate (ORR) to CTX was 44.6% in the anti-PD-1-exposed group and 19.6% in the anti-PD-1-naïve group (p=0.001); the median progression-free survivals (PFS) were 3.7 months and 3.3 months (HR=0.82, p=0.20), respectively. Among patients receiving taxanes plus ramucirumab (n=149), ORR (60.6% vs 20.0%, p<0.001) and median PFS (4.8 vs 3.4 months, p=0.004, HR=0.56) were significantly better in the anti-PD-1-exposed group (n=39) compared with the anti-PD-1-naïve group (n=110). These differences were not observed in patients receiving taxane monotherapy (n=34) or irinotecan (n=50). CTx after anti-PD-1 therapy showed no severe or unexpected adverse events.

CONCLUSIONS

Prior anti-PD-1 therapy might increase tumour response to taxanes plus ramucirumab without unexpected adverse events, which warrants further investigations in a large cohort.

Clinical and molecular features of responders to PD-1 blockade for patients with microsatellite instability high or mismatch repair deficient advanced gastrointestinal tumors

e16550

Background: An anti-PD-1 inhibitor pembrolizumab showed a durable response for patients with microsatellite instability high (MSI-H) or mismatch repair deficient (dMMR) advanced solid tumors. However, clinical and molecular features of responders to PD-1 blockade for MSI-H/dMMR advanced gastrointestinal (GI) tumors are not well understood. Methods: Patients with MSI-H/dMMR GI tumors who received anti‒PD-1 monotherapy were enrolled in this study. PD-L1 expression in tumor cells or immune cells as well as combined positive score (CPS) were assessed using the PDL1 IHC 22C3 pharmDx assay. Cancer genome alterations were evaluated by a next generation sequencing-based panel with Oncomine Comprehensive Assay for tumor tissue samples or Guardant360 ctDNA Assay for plasma samples. Results: A total of 43 patients with gastric cancer (n = 19), colorectal cancer (n = 16), cholangiocarcinoma (n = 4), small intestine cancer (n = 2) and pancreatic cancer (n = 2) were analyzed in this study. All patients had measurable lesions and objective response was observed in 20 patients (46%). Objective response rate (ORR) was significantly higher in patients with ECOG PS of 0 than in those with PS of 1 or 2 (64% vs. 22%, p = 0.01) and PD-L1+ in tumor cells than in those with PD-L1- in tumor cells (67% vs. 32%, p = 0.03). ORR was similar according to PD-L1 CPS; 45% in CPS < 1, 47% in CPS ≥1 and 56% in CPS ≥10, respectively. ORR was numerically lower in patients with PTEN mutation than in those with PTEN wild type (29% vs. 56%). Also, durable response rate (objective response lasting continuously ≥6 months) was significantly lower in patients with PTEN mutation than in those with PTEN wild type (0% vs. 52%, p = 0.03). In the overall population, median progression-free survival (PFS) was 10.0 months (95% CI, 4.0-not reached). In univariate analysis, PS (1 or 2 vs. 0) was the strongest clinical factor associated with PFS (3.9 months vs. not reached, HR 3.9; 95% CI 1.7-9.2, p = 0.002). After adjusted by PS, PTEN mutation was only molecular factor associated with shorter PFS (3.4 vs. 24.5 months, HR 3.0; 95% CI 1.1-8.4, p = 0.03). Conclusions: Some clinical and molecular factors were associated with response to PD-1 blockade for MSI-H/dMMR advanced GI tumors. Updated biomarker analysis with whole exome sequencing and multiplex IHC will be presented.

TAS-116, an oral HSP90 inhibitor, in combination with nivolumab in patients with colorectal cancer and other solid tumors: An open-label, dose-finding, and expansion phase Ib trial (EPOC1704)

4044

Background: Regulatory T cells (Tregs) potentially induce the resistance of anti-PD1/PD-L1 inhibitors (A-PD1). TAS-116, a novel HSP90 inhibitor, enhanced antitumor immunity via reducing Tregs in vitro and in vivo. Combination of TAS-116 plus A-PD1 showed a superior tumor growth suppression compared with either treatment alone in vivo. Based on the above, we investigated safety and efficacy of TAS-116 in combination with nivolumab in patients with solid tumors. Methods: Enrolled patients received TAS-116 plus nivolumab in a dose-finding part to estimate the maximum tolerated dose and the recommended phase 2 dose (RP2D). Additional patients were enrolled in a dose-expansion part. TAS-116 monotherapy (orally once daily, 80mg on level 1, 120mg on level 2, and 160mg on level 3) was administrated for 2 weeks followed by the combination with nivolumab (intravenously every 2 weeks, 3 mg/kg). The primary endpoint was dose-limiting toxicities (DLTs) during the first cycle (4 weeks). PD-L1 combined positive score (CPS) and tumor mutation burden (TMB) were assessed. We also conducted biomarker research using paired samples from repeated tumor biopsies and blood collections. Results: A total of 44 patients with colorectal cancer (CRC, n = 29), gastric cancer (GC, n = 8), sarcoma (n = 5), non-small cell lung cancer (NSCLC, n = 1) and melanoma (n = 1) after standard of cares were enrolled. One patient had MSI-H CRC, but all other patients had MSS tumors. No DLTs were observed at all levels and TAS-116 160 mg was determined as RP2D. The common grade 3 or worse treatment-related adverse included AST/ALT increased (7%), creatinine increased (5%) and platelet count decreased (5%). Objective tumor response was observed in 6 patients including 4 MSS CRC, 1 MSI-H CRC and 1 sarcoma, resulting in objective response rate (ORR) of 16% in MSS CRC without prior A-PD-1. PD-L1 CPS and TMB could be evaluated in 18 and 17 MSS CRC without prior A-PD-1, respectively. ORR was 27% in patients with CPS ≥1 and 0% in patients with CPS < 1. ORR was 33% with TMB-high (median as the cut-off) and 12% with TMB-low. Analysis of tumor-infiltrating lymphocytes before treatment and after TAS-116 monotherapy demonstrated reduction of FoxP3hiCD45RA−Tregs fraction in the tumor microenvironment. Conclusions: The combination of TAS-116 160mg plus nivolumab had manageable safety profiles and anti-tumor activity especially for MSS CRC patients, which warrants further investigations in a large cohort. Clinical trial information: UMIN000032801 .

The skin types closely related to development of the facial acneiform rash and the therapeutic effects of EGFR inhibitors in RAS wild-type metastatic colorectal cancer: Ancillary analysis of FAEISS study

3637

Background: At ESMO2019, we reported the primary results of a randomized controlled trial (FAEISS study) investigating the efficacy of topical corticosteroid treatment to facial acneiform rash (AR) by EGFR inhibitors comparing groups starting with a very strong topical corticosteroid and the standard weak topical corticosteroid. As an ancillary analysis, we investigated the association between AR and the pre-treatment skin types, as well as between the skin types and therapeutic effects of EGFR inhibitors on the primary disease. Methods: Utilizing pre-treatment clinical photos of the face taken according to the method determined by FAEISS study protocol, we divided the skin types into categories including enlarged pore, oiliness, xerosis, wrinkles, skin color/redness, and allocated the score (1-3) by central review. The severity of AR occurred during the study was graded and was evaluated the association with the specific skin type by Fisher’s exact test. We also investigated the association between the skin types and the best overall response (RECISTv1.1) to EGFR inhibitor therapy on the primary disease using the Cochran-Armitage trend test. Results: Of the registered 172 cases of RAS wild-type metastatic colorectal cancer [104 men and 68 women, median age = 68 (26-79)], omitting the cases with unevaluable data, finally we analyzed 146 cases for associations between the skin types and AR and 147 cases for best overall response. Interestingly, AR developed 13.6% of enlarged pore score 1, 29% of score 2 and 45.8% of score 3, and patients with enlarged pore tended to have more AR (p = 0.058). Surprisingly, the response(CR/PR/SD) of the primary disease were 59.1% of the enlarged pore score 1, 70.6% of score 2 and 87.0% of score 3, and showed statistically significant trend(p < 0.038). Conclusions: This study suggested that a skin type (enlarged pore) is a possible marker predicting AR risk in EGFR inhibitor therapy for RAS wild-type metastatic colorectal cancer, and better therapeutic effects of EGFR inhibitors.

Phase 1 study of napabucasin, a cancer stemness inhibitor, in patients with advanced solid tumors

PURPOSE

Napabucasin is a cancer stemness inhibitor that targets a number of oncogenic pathways, including signal transducer and activator of transcription 3 (STAT3). Phase 1/2 studies suggest tolerability and anti-tumor activity in various types of cancer; a Phase 3 study of napabucasin plus standard therapy in colorectal cancer is ongoing. This is a Phase 1 dose-escalation study in patients with advanced solid tumors, and the first study of napabucasin in Japanese patients.

METHODS

Patients received napabucasin 480, 960, or 1440 mg daily in 28-day cycles until disease progression or intolerable toxicity. Primary objectives were to determine dose-limiting toxicities (DLTs), maximum tolerated dose (MTD), and the pharmacokinetic (PK) profile of napabucasin. Blood samples were taken for PK analysis on Days 1, 2, 8, and 15 of Cycle 1, and Days 29 and 30 of Cycle 2. Secondary objectives were to assess napabucasin antitumor activity, and the relationship between biomarkers and antitumor activity. JapicCTI-No: JapicCTI-132152.

RESULTS

Enrolled were 14 patients (480 mg [n = 3], 960 mg [n = 4], 1440 mg [n = 7]). One patient experienced a DLT (Grade 3, anorexia). MTD was 1440 mg/day. Most common drug-related adverse events were diarrhea (n = 9), nausea (n = 4), vomiting (n = 3), and anorexia (n = 3). Napabucasin showed a similar PK profile to previous studies and no abnormal accumulation was observed. Following treatment, two patients had stable disease; the remaining 12 had progressive disease.

CONCLUSION

Napabucasin was well-tolerated at doses up to 1440 mg/day in Japanese patients with advanced solid tumors; the PK profile was comparable to that reported previously.

Regorafenib Plus Nivolumab in Patients With Advanced Gastric or Colorectal Cancer: An Open-Label, Dose-Escalation, and Dose-Expansion Phase Ib Trial (REGONIVO, EPOC1603)

PURPOSE

This is a phase Ib trial of regorafenib plus nivolumab for gastric and colorectal cancer.

PATIENTS AND METHODS

Enrolled patients received regorafenib plus nivolumab in a dose-finding part to estimate the maximum tolerated dose. Additional patients were enrolled in a dose-expansion part. Regorafenib of 80-160 mg was administered once daily for 21 days on/7 days off with nivolumab 3 mg/kg every 2 weeks. The primary end point was dose-limiting toxicity (DLT) during the first 4 weeks to estimate the recommended dose.

RESULTS

Fifty patients (25 each with gastric and colorectal cancer) were enrolled. All patients had received ≥ 2 previous lines of chemotherapy, including anti-angiogenetic inhibitors in 96% of patients. Seven patients with gastric cancer had previously been treated with immune checkpoint inhibitors. One patient had microsatellite instability-high colorectal cancer, whereas the remaining patients had microsatellite stable or mismatch repair-proficient tumors. Three DLTs (grade 3 colonic perforation, maculopapular rash, and proteinuria) were observed with regorafenib 160 mg; none were observed with 80 or 120 mg. During the dose-expansion part, regorafenib dose was reduced from 120 to 80 mg because of frequent maculopapular rash. The common grade ≥ 3 treatment-related adverse events were rash (12%), proteinuria (12%), and palmar-plantar erythrodysesthesia (10%). Objective tumor response was observed in 20 patients (40%), including 11 with gastric cancer (44%) and 9 with colorectal cancer (36%). Median progression-free survival was 5.6 and 7.9 months in patients with gastric and colorectal cancer, respectively.

CONCLUSION

The combination of regorafenib 80 mg plus nivolumab had a manageable safety profile and encouraging antitumor activity in patients with gastric and colorectal cancer, which warrants additional investigations in larger cohorts.

The Impact of Molecular Subtype on Efficacy of Chemotherapy and Checkpoint Inhibition in Advanced Gastric Cancer

PURPOSE

We evaluated the association between molecular subtypes of advanced gastric cancer (AGC) and the efficacy of standard chemotherapy or immune checkpoint inhibitors.

EXPERIMENTAL DESIGN

Patients with AGC who received systemic chemotherapy from October 2015 to July 2018 with available molecular features were analyzed. We investigated the efficacy of standard first- (fluoropyrimidine + platinum ± trastuzumab) and second-line (taxanes ± ramucirumab) chemotherapy, and subsequent anti-PD-1 therapy in patients with four molecular subtypes: MMR-D (mismatch repair deficient), EBV⁺, HER2⁺, and all negative.

RESULTS

410 patients were analyzed: MMR-D 5.9%, EBV⁺ 4.1%, HER2⁺ 13.7%, and all negative 76.3%. In 285 patients who received standard first-line chemotherapy, the median progression-free survival (PFS) times were 4.2, 6.0, 7.5, and 7.6 months and the objective response rates (ORR) were 31%, 62%, 60%, and 49% in MMR-D, EBV⁺, HER2⁺, and all-negative subtypes, respectively. Multivariate analysis showed shorter PFS in MMR-D versus all-negative patients [HR, 1.97; 95% CIs, 1.09-3.53; P = 0.022]. In second-line setting, there were no significant differences in efficacy. In 110 patients who received anti-PD-1 therapy, median PFS times were 13.0, 3.7, 1.6, and 1.9 months and the ORRs were 58%, 33%, 7%, and 13%, respectively. Twelve patients with MMR-D received subsequent anti-PD-1 therapy and showed longer PFS compared with that in 10 (83%) patients who received earlier-line chemotherapy.

CONCLUSIONS

MMR-D might result in shorter PFS with first-line chemotherapy for AGC. Subsequent anti-PD-1 therapy achieved higher ORR and longer PFS than prior chemotherapy in most patients with MMR-D, supporting the earlier use of immune checkpoint inhibitors.

Safety and efficacy of pembrolizumab in combination with S-1 plus oxaliplatin as a first-line treatment in patients with advanced gastric/gastroesophageal junction cancer: Cohort 1 data from the KEYNOTE-659 phase IIb study

AIM

The KEYNOTE-659 study evaluated the efficacy and safety of pembrolizumab in combination with chemotherapy as the first-line treatment in Japanese patients with advanced gastric/gastroesophageal junction (G/GEJ) cancer. In this paper, we report results from cohort 1 (S-1 plus oxaliplatin [SOX] with pembrolizumab).

METHODS

This was a non-randomised, multicentre, open-label phase IIb study in patients with advanced programmed death-ligand 1 (PD-L1)-positive, human epidermal growth factor receptor 2-negative G/GEJ tumours. The primary endpoint was the objective response rate (ORR) assessed by blinded independent central review (BICR). Secondary endpoints were duration of response (DOR), disease control rate (DCR), time to response (TTR), progression-free survival (PFS), overall survival (OS) and safety. Exploratory analyses were performed based on the PD-L1 combined positive score (CPS) status.

RESULTS

Fifty-four patients were evaluated. The median follow-up was 10.1 months. ORR and DCR by BICR were 72.2% (95% confidence interval [CI] 58.4-83.5) and 96.3% (95% CI 87.3-99.5), respectively. Median DOR, TTR, PFS and OS were as follows: not reached, 1.5 months, 9.4 months and not reached. The ORR was 73.9% in patients with CPS ≥1 to <10 and 71.0% in those with CPS ≥10. Grade ≥3 treatment-related adverse events (TRAEs) were reported by 57.4% of patients. The most common grade ≥3 TRAEs were decreased platelet count (14.8%), decreased neutrophil count (13.0%), colitis (5.6%) and adrenal insufficiency (5.6%).

CONCLUSIONS

SOX with pembrolizumab showed encouraging efficacy and a manageable safety profile for the first-line treatment of advanced G/GEJ cancer.

TRIAL REGISTRATION

NCT03382600/JapicCTI-183829.

Updated results from a phase Ib trial of regorafenib plus nivolumab in patients with advanced colorectal or gastric cancer (REGONIVO, EPOC1603)

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Background: In the phase 1 REGONIVO study, regorafenib of 80 mg/day plus nivolumab showed manageable safety profiles and encouraging anti-tumor activity for advanced colorectal cancer (CRC) or gastric cancer (GC) with objective response rate (ORR) of 36% in CRC and 44% in GC (Fukuoka, et al. ASCO 2019). Updated efficacy results are presented. Methods: Enrolled patients (pts) received regorafenib plus nivolumab in a dose-finding phase to estimate the maximum tolerated dose (MTD). Additional pts were enrolled in a dose-expansion phase. Regorafenib of 80 to 160 mg was administered once daily for 21 on 7 days off with nivolumab 3 mg/kg every 2 weeks. The primary endpoint was dose-limiting toxicity (DLT) during cycle one to estimate the MTD and the recommended dose. PD-L1 combined positive score (CPS) was assessed using the anti–PD-L1 28-8 antibody. Tumor mutation burden (TMB) was measured using Oncomine tumor mutation load assay. Results: Fifty pts were enrolled (25 CRC; 25 GC) until October 2018 with median prior treatment line of 3. Efficacy results were updated as of September 1st 2019. One CRC pt was with MSI-high but all other pts were with MSS or MMR-proficient. Among the 20 pts (9 CRC and 11 GC) with objective response (40%), responses are still ongoing in 13 pts (7 CRC and 6 GC) and the median duration of response was not reached (NR). Median progression free survival (PFS) was 7.8 months in CRC (95% CI, 2.8- NR) and 5.5 months (95% CI, 2.6-10.2 months) in GC. One-year PFS rate was 41.7% in CRC and 22.4% in GC. Median overall survival (OS) was not reached in CRC (95% CI, 9.7-NR) and 12.1 months (95% CI, 5.2-NR) in GC. One-year OS rate was 68% in CRC and 55.3% in GC. No significant difference of PFS and ORR was observed in CRC according to PD-L1 and TMB. Conclusions: Encouraging anti-tumor activity of the combination of regorafenib plus nivolumab had been maintained with long-term follow-up. A randomized study for MSS CRC is under planning. Clinical trial information: NCT03406871.

Survival impact on regorafenib (REG) and trifluridine/tipiracil hydrochloride (FTD/TPI) for patients with metastatic colorectal cancer: Single institutional experience

43

Background: Regorafenib (REG) and trifluridine/tipiracil hydrochloride (FTD/TPI) demonstrated overall survival (OS) benefit in patients (pts) with metastatic colorectal cancer (mCRC) in the CORRECT and RECOURSE phase III trials. In Japan, REG and FTD/TPI have been approved in 2013 and 2014, respectively. However, little is known about survival impact on these agents in the real-world setting. Therefore, the aim of this retrospective study was to evaluate the effects of REG and FTD/TPI in pts with mCRC. Methods: We collected medical records from consecutive 1142 pts who had been initiated with first-line chemotherapy for mCRC from 2008 to 2016 at National Cancer Center Hospital East. The survival outcomes were compared between pts from 2008 to 2011 (cohort A) and those from 2012 to 2016 (cohort B). This study excluded pts who have not been refractory or intolerant to standard chemotherapy including fluoropyrimidine, oxaliplatin, irinotecan, and anti-EGFR antibody if KRAS exon 2/ RAS wild-type tumors. Results: A total of 590 pts were analyzed (cohort A; N = 236 and cohort B; N = 354). More patients received at least one of REG or FTD/TPI in cohort B (16.1% vs. 59.9%, p < 0.001). The time from initiation to end of standard chemotherapy was comparable between the two cohort (20.0 vs. 17.5 months, p = 0.266). With a median follow-up period of 34.9 months, salvage-line OS (sOS) after standard chemotherapy was significantly longer in cohort B (4.8 vs. 6.6 months, p = 0.001), while there was only a favorable trend in cohort B in terms of OS from start of first-line treatment (27.3 vs. 28.5 months, p = 0.516). In cohort B, pts who sequentially received both of REG and FTD/TPI showed longest sOS (median, both of REG and FTD/TPI; 11.3 months, either REG or FTD/TPI; 7.0 months, neither REG nor FTD/TPI; 3.1 months). Conclusions: Our study showed that REG and FTD/TPI led to prolongation of sOS in the real-world setting, indicating the importance of strategies which make all active agents available to pts with mCRC.

An open-label phase II study of lenvatinib plus pembrolizumab in patients with advanced gastric cancer (EPOC1706)

374

Background: Pembrolizumab, anti–PD-1 antibody, provides response rates of around 15% in patients (pts) with PD-L1-positive advanced gastric cancer (AGC). Lenvatinib, a multikinase inhibitor of VEGF receptors and other receptor tyrosine kinases, substantially decreased the tumor-associated macrophages and increased infiltration of CD8-positive T cells and enhanced anti-tumor activity of PD-1 inhibitors in vivo model. This phase 2 study has been conducted to evaluate efficacy and safety of the combination of lenvatinib plus pembrolizumab in pts with AGC. Methods: Eligible pts were with AGC having measurable lesions according to RECIST ver. 1.1. Pts could be enrolled regardless of PD-L1 status. Pts received 20 mg oral lenvatinib daily plus 200 mg intravenous pembrolizumab every 3 weeks. Primary endpoint was objective response rate (ORR). Planned sample size was 29 pts based on Simon’s optimal two-stage design with one-sided ɑ = 5% and power = 80%. The threshold and expected ORRs were 10% and 30%. PD-L1 combined positive score (CPS) was assessed using the anti–PD-L1 22C3 antibody. Results: From October 2018 to March 2019, 29 pts (27 MSS and 2 MSI-H) were enrolled and assessed for anti-tumor response. Fourteen pts received the study treatment as first-line and 15 pts as second-line. ORR was 69% (95% CI 49 to 85). The disease control rate was 100%. ORR in MSS pts was 70%. ORR was numerically higher in pts with CPS≥1 (n=19, ORR 84%) than that of pts with CPS<1 (n = 10, ORR 40%). Median progression-free survival was 6.9 months (95% CI, 4.4-9.4 months) with 14 pts with ongoing treatment at the data cut off in August 2019. Grade ≥ 3 treatment related adverse events occurred in 13 pts (45%) including hypertension (34%), proteinuria (17%), and platelet count decreased (7%). Conclusions: Lenvatinib with pembrolizumab showed a promising antitumor activity with acceptable safety profiles for pts with AGC, which warrants further investigations in a larger cohort. Clinical trial information: NCT03609359 .

Scoop: Multicenter phase I/II trial of BBI608 and pembrolizumab in patients with metastatic colorectal cancer (EPOC1503)

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Background: The anti–PD-1 antibody pembrolizumab (P) provides response rates of 28-57% in patients (pts) with MSI-H metastatic colorectal cancer (mCRC) vs 0% in those with non-MSI-H cancers. STAT3 has been previously reported as a potential key driver of immune evasion. This study investigates efficacy and safety for the combination of BBI608 (napabucasin), which blocks phosphorylated STAT3 and downregulates IDO1 and PD-L1, with P, in pts with mCRC. BBI608 480 mg BID with P was determined as the recommended phase II dose in phase I. Methods: Phase II included Cohorts A (MSI-H) and B (non-MSI-H). Pts with mCRC not responding to or intolerant of standard chemotherapies were enrolled. The primary endpoint was immune-related objective response rate (irORR), according to irRECIST. The sample size for Cohort A (10 pts) was derived in an exploratory manner. In Cohort B, assuming null and alternative hypotheses of irORR = 5% and 20% led to an estimated required sample size of 40 pts, with a 1-sided alpha of 5% and power of 90%. Genomic profiles and the consensus molecular subtypes (CMS) of colorectal cancer were determined by whole exome sequencing and RNA sequencing as previously described. Results: From Feb/2017 to Jun/2018, 10 pts were enrolled in Cohort A and 40 in Cohort B. The irORR was 50% (5 of 10 pts) in Cohort A and 10% (95% CI 2.8 to 23.7) (4 of 40 pts) in Cohort B. Of evaluable 19 pts for CMS classification in Cohort B, CMS1, CMS2, CMS3, and CMS4 were detected in 3, 6, 4, and 6 cases, respectively. The irORR was 33% (1 of 3 pts), 0% (0 of 6 pts), 25% (1 of 4 pts), 33% (2 of 6 pts) in CMS1, CMS2, CMS3, and CMS4, respectively. One CMS3 patient with partial response had POLE mutation, while 1 CMS1 and 2 CMS4 pts with partial response did not. The most common grade 3 or higher treatment-related adverse events included fever (10%) in Cohort A, and diarrhea (5%) and appetite loss (7.5%) in Cohort B, without unexpected safety signals. No treatment-related deaths occurred. Conclusions: BBI608 with P showed encouraging anti-tumor activity with acceptable toxicity for non-MSI-H mCRC pts as well as MSI-H mCRC pts. Impact of CMS on the efficacies of this combination warrants further investigation in the additional cohort of this study. Clinical trial information: NCT02851004.

Trifluridine/tipiracil for the treatment of metastatic gastric cancer

Introduction: Trifluridine/tipiracil is a novel oral cytotoxic chemotherapy consisting of a thymidine-based nucleoside analog, trifluridine, and a thymidine phosphorylase inhibitor, tipiracil. Trifluridine/tipiracil was approved for the treatment of metastatic colorectal cancer refractory to standard therapies. A phase II trial in Japan demonstrated that this therapy has antitumor activity and is tolerated by patients with advanced gastric cancer (AGC); as a result, the phase III TAGS trial (Trifluridine/tipiracil versus placebo in patients with heavily pretreated metastatic gastric cancer) was initiated.Area covered: Trifluridine/tipiracil has proved effective for heavily pretreated AGC and has thus been approved for use in the United States in February 2019, Japan in August 2019 and the European Union in September 2019. Detail of the phase III TAGS trial is discussed in this review.Expert opinion: Trifluridine/tipiracil after at least two previous courses of systemic chemotherapy improved rates of survival of gastric cancer; thus it has become one of the treatment options in affected patients. Currently, several clinical trials of trifluridine/tipiracil in combination with other anticancer agents such as ramucirumab (an anti-vascular endothelial growth factor receptor 2 monoclonal antibody) for patients with AGC are ongoing.

Molecular landscape and prognostic value of HER2 low-expression on metastatic colorectal cancer

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Background: HER2 dual blockade showed the promise in clinical trials in patients (pts) with HER2-positive (HER2-Pos) metastatic colorectal cancer (mCRC). A phase I/II study of a novel anti-HER2 antibody-drug conjugate (HER2-ADC) showed promising activities across different cancer subtypes including HER2-Pos mCRC, and also showed a hint of activity for low-expressing (HER2-L) mCRC, regardless of RAS mutation. However, molecular landscape and prognostic value of HER2-L on mCRC are unclear. Methods: The eligibility included pts with mCRC who had undergone surgical resection of primary tumor. Using the specimen, HER2 expression was evaluated by immunohistochemistry (IHC) and FISH. Definition of HER2 positivity was as follows; HER2-Pos as IHC 3+ or IHC 2+/FISH positive: HER2-L as IHC 2+/FISH negative or IHC 1+: Negative (HER2-Neg) as IHC 0+. NGS tests were also done. Results: Between 2005 and 2015, a total of 370 pts were analyzed; 60% were male, with a median age of 64 y/o. Fifteen pts (4%) with HER2-Pos, 21 (6%) with HER2-L, and 334 (90%) with HER2-Neg were identified. Proportion of left-sided primary tumor was similar among groups ranging from 72% to 78%. No difference was observed in terms of major clinicopathological characteristics. The proportion of co-altered RAS mutations in HER2-L was significantly higher than HER2-Pos ( p = 0.037) and similar to HER2-Neg (27% in HER2-Pos vs. 62% in HER2-L vs. 56% in HER2-Neg). As of median follow-up of 24.8 months, median overall survival (mOS) in HER2-L was significantly better than that in HER2- Pos ( p = 0.029, 18.2 months in HER2-Pos vs. 33.3 in HER2-L vs. 27.9 in HER2-Neg). In 58 pts harboring RAS wild-type who received an anti-EGFR monoclonal antibody therapy, median progression-free survival (mPFS) in HER2-L tended to be better than that in HER2- Pos, with 2.2 months in HER2-Pos, 7.8 in HER2-L, and 5.5 in HER2-Neg ( p = 0.099). Conclusions: Since HER2-L mCRC had the high prevalence of co-altered RAS mutations but showed a better prognosis and might benefit more from an anti-EGFR therapy than HES2-Pos, the HER2-L mCRC seems to have a different biological behavior from HER2-Pos in terms of molecular landscape and prognostic value on mCRC.

S-1+oxaliplatin with pembrolizumab for advanced gastric cancer: The cohort 1 in a phase IIb KEYNOTE-659 study

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Background: The KEYNOTE-059 study showed the preliminary antitumor activity and tolerability of chemotherapy with pembrolizumab (P) for advanced gastric cancer (AGC). In Japan, S-1 + platinum regimen is a standard chemotherapy for AGC. The KEYNOTE-659 study (NCT03382600) investigated the efficacy and safety of S-1 + oxaliplatin (SOX; cohort 1) or cisplatin (SP; cohort 2) with P as the first line treatment in patients (pts) with human epidermal growth factor receptor 2 (HER2)-negative, programmed death-ligand 1 (PD-L1)-positive AGC. Here, we report the results of cohort 1. Methods: The key inclusion criteria were as follows: age ≥18 to ≤75 years; an ECOG performance status of 0 or 1; and chemotherapy-naïve, HER2-negative and PD-L1-positive AGC. PD-L1 positivity was defined as a combined positive score of ≥1 using the IHC 22C3 PharmDx assay. An S-1 dose of 40-60 mg per dose was orally administered, twice daily, for the first 2 weeks of a 3-week cycle. P (200 mg) and oxaliplatin (OX; 130 mg/m2) were administered on day 1 of each cycle. The primary endpoint was overall response rate (ORR) that was assessed by a blinded independent central review (BICR). The secondary endpoints were progression-free survival (PFS), overall survival (OS), disease control rate (DCR), duration of response (DOR), and safety. Results: From April to September 2018, 54 pts were enrolled at 25 sites in Japan. The median follow-up time was 10.1 months. The median number of P doses and cycles in SOX were 9 (range, 2-18) and 6 (range, 2-13), respectively. The relative dose intensities of S-1 and OX were 73% and 60%, respectively. The ORR and DCR assessed by BICR were 72.2% (95% CI 58.4-83.5) and 96.3% (95% CI 87.3-99.5), respectively. The median PFS was 9.4 months (95% CI 6.6-NR). Median DOR and OS were not reached. Grade ≥3 adverse events (AEs) were reported in 31 pts (57.4%). The most common treatment-related AEs of grade ≥3 were thrombocytopenia (14.8%), neutropenia (13.0%), colitis (7.4%), and adrenal insufficiency (5.6%). There were no treatment-related deaths. Conclusions: This study showed the encouraging efficacy and manageable safety of SOX with P therapy as a first line in pts with HER2-negative, PD-L1-positive AGC. Clinical trial information: NCT03382600.

Efficacy and safety of nab-paclitaxel plus ramucirumab versus paclitaxel plus ramucirumab as second-line treatment for patients with advanced gastric cancer: A single institutional experience

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Background: Nanoparticle albumin-bound (nab)- paclitaxel (PTX) was non-inferiority to solvent-based paclitaxel as second-line for advanced gastric cancer (AGC) with fewer infusion-related reactions and a trend toward improved overall survival (OS) in patients (pts) with peritoneal metastasis (PM) or ascites in ABSOLUTE trial (Shitara K et al. Lancet Gastroenterol Hepatol. 2017). Furthermore, safety and efficacies of nab-PTX plus ramucirumab (RAM) was reported in a phase II trial (Bando H, et al. EJC 2018), although no randomised trial with PTX plus RAM is reported so far. Methods: We retrospectively reviewed consecutive pts with AGC receiving nab-PTX plus RAM or PTX plus RAM as second-line chemotherapy from June 2015 to January 2019 at the National Cancer Center Hospital East. Adverse events were evaluated using Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Progression-free survival (PFS) was calculated using the Kaplan-Meier method, and the differences were evaluated using the log-rank test. Results: A total of 257 pts were included for analysis with 118 pts treated with nab-PTX plus RAM and 139 pts with PTX plus RAM. 151 pts (59%) had peritoneal metastasis and 76 pts (30%) were associated with moderate or massive amounts of ascites. Objective response rates were similar between two groups (nab-PTX plus RAM 34.1% vs. PTX plus RAM 28.0%, p = 0.36). There were no significant differences in PFS (median 3.9 vs. 3.9 months, log-rank p = 0.34; hazard ratio [HR] = 1.14). HR of PFS was 0.96 in pts with PM and 0.79 in pts with moderate or massive ascites. The major grade 3 or higher adverse events were neutropenia (nab-PTX plus RAM 55.1% vs. PTX plus RAM 55.4%), leucopenia (28.8 vs. 35.3%), thrombocytopenia (5.1 vs. 2.9%), and febrile neutropenia (5.1 vs 9.4%). Conclusions: Efficacy and safety of nab-PTX plus RAM were comparable to those of PTX plus RAM in pts with AGC in clinical practice. nab-PTX plus RAM is a treatment option as second-line treatment in pts with AGC.

Retrospective cohort study of trifluridine/tipiracil (TAS-102) plus bevacizumab versus trifluridine/tipiracil monotherapy for metastatic colorectal cancer

Background

A previous phase I/II C-TASK FORCE study of trifluridine/tipiracil plus bevacizumab for patients with heavily pretreated metastatic colorectal cancer (mCRC) showed promising activity with an acceptable toxicity profile. This retrospective study aimed to investigate the safety and efficacy of trifluridine/tipiracil plus bevacizumab compared with trifluridine/tipiracil monotherapy in patients with heavily pretreated mCRC in clinical settings.

Methods

Records of patients with mCRC refractory to standard therapies who initiated trifluridine/tipiracil plus bevacizumab from January 2016 to March 2018 or trifluridine/tipiracil monotherapy from June 2014 to December 2015 were retrospectively reviewed at our institution.

Results

Totally, 60 patients received trifluridine/tipiracil plus bevacizumab and 66 received trifluridine/tipiracil monotherapy. All patients had previously received standard chemotherapy. Median progression-free survival (PFS) was 3.7 months [95% confidence interval (CI), 2.3–5.1] in the trifluridine/tipiracil plus bevacizumab group and 2.2 months (95% CI, 1.8–2.6) in the trifluridine/tipiracil monotherapy group [hazards ratio (HR) 0.69; 95% CI 0.48–0.99]. PFS rate at 16 weeks was 46.6% for the trifluridine/tipiracil plus bevacizumab group and 33.9% for the trifluridine/tipiracil monotherapy group. Although a relatively higher incidence of grade ≥ 3 neutropenia was observed in the trifluridine/tipiracil plus bevacizumab group than that in the other group (50.0% vs. 40.9%, p = 0.371), the incidence of febrile neutropenia was not high (3.3% vs. 7.8%, p = 0.444).

Conclusions

In real-world settings, trifluridine/tipiracil plus bevacizumab prolonged PFS and helped achieve higher 16-week PFS rate compared with trifluridine/tipiracil monotherapy in patients with heavily pretreated mCRC with manageable toxicities.

Trial registration

Retrospectively registered.