Real-World Outcomes of Patients Treated With Neoadjuvant Imatinib for Locally Advanced, Recurrent and Limited Metastatic Gastrointestinal Stromal Tumour in an Australian Cancer Training Network.

Gastrointestinal Stromal Tumors: Disease and Treatment Update

Although imatinib is a standard treatment for metastatic or recurrent gastrointestinal stromal tumors (GISTs), acquired c-kit mutations reportedly cause secondary resistance to imatinib. Sunitinib is a tyrosine kinase inhibitor (TKI) that can be used as second-line therapy in imatinib-resistant or -intolerant GISTs. For sunitinib-resistant or -intolerant GISTs, regorafenib is a standard third-line treatment. Although TKI therapies have revolutionized the treatment of recurrent or metastatic GISTs, they cannot cure GISTs. Therefore, in the era of TKIs, role of cytoreductive surgery for recurrent or metastatic GISTs has been discussed. Retrospective studies of treatment strategies with front-line surgery prior to imatinib have shown that initial cytoreduction confers no benefit in cases of advanced or recurrent GIST, and administering imatinib is the principle treatment. Most retrospective studies report cytoreductive surgery to be feasible in patients with metastatic GIST whose disease is stable or responsive to imatinib. Cytoreductive surgery may be indicated in limited disease progression refractory to imatinib when complete resection is possible, but case selection is critical. Cytoreductive surgery for metastatic GIST treated with sunitinib seems less feasible because of high rates of incomplete resections and complications. The role of cytoreductive surgery for metastatic GISTs would be difficult to establish in a prospective study; individualized treatments need to be carefully designed based on c-kit and platelet-derived growth factor receptor alpha (PDGFRA) mutations and other factors.

The prognosis of advanced gastrointestinal stromal tumors (GISTs) was dramatically improved in the era of imatinib. Cytoreduction surgery was advocated as an additional treatment for advanced GISTs, especially when patients having poor response to imatinib or developing resistance to it. However, the efficacy and benefit of cytoreduction were still controversial. Likewise, the sequence between cytoreduction surgery and imatinib still need evaluation. In this study, we tried to assess the feasibility and efficiency of cytoreduction in advanced GISTs. Furthermore, we analyzed the impact of timing of the cytoreduction surgery on the prognosis of advanced GISTs.We conducted a prospective collecting retrospective review of patients with advanced GISTs (metastatic, unresectable, and recurrent GISTs) treated in Chang Gung memorial hospital (CGMH) since 2001 to 2013. We analyzed the impact of cytoreduction surgery to response to imatinib, progression-free survival (PFS), and overall survival (OS) in patients with advanced GISTs. Moreover, by the timing of cytoreduction to imatinib, we divided the surgical patients who had surgery before imatinib use into early group and those who had surgery after imatinib into late. We compared the clinical response to imatinib, PFS and OS between early and late cytoreduction surgical groups.Totally, 182 patients were enrolled into this study. Seventy-six patients underwent cytoreduction surgery. The demographic characteristics and tumor presentation were similar between surgical and non-surgical groups. The surgical group showed better complete response rate (P < 0.001) and partial response rate (P = 0.008) than non-surgical group. The 1-year, 3-year, and 5-year PFS were significantly superior in surgical group (P = 0.003). The 1-year, 3-year, and 5-year OS were superior in surgical group, but without statistical significance (P = 0.088). Dividing by cytoreduction surgical timing, the demographic characteristics and tumor presentation were comparable in early and late groups. The late cytoreduction group presented higher R0 resection rate (59.1% vs 31.5%, P = 0.025). However, the PFS and OS were comparable in both groups.Combining imatinib with cytoreduction increased the response rate to imatinib and prolonged PFS in patients with advanced GISTs. Moreover, early and late cytoreduction surgery was comparable in prognosis, although late cytoreduction revealed higher complete resection rate.

Role of Operative Therapy in Treatment of Metastatic and/or Recurrent Gastrointestinal Stromal Tumors

Several doubts remain regarding the optimal use of neoadjuvant imatinib in gastrointestinal stromal tumors (GISTs), such as ideal treatment duration, patient selection, and long-term survival outcomes. This manuscript provides a comprehensive review on neoadjuvant imatinib treatment outcomes and facilitate evidence-based decision-making for the use of imatinib therapy in GISTs. Four databases (PubMed, EMBASE, Scopus, and Cochrane Library) were searched from inception to September 9, 2023. Meta-analyses of proportions were performed for the outcomes of R0 resection, disease responses, and 1-year, 3-year, and 5-year overall survival (OS) as well as 1-year, 3-year, and 5-year disease free survival (DFS). Sensitivity analyses in the form of leave-one-out analyses, meta-regression, and subgroup analyses were performed for outcomes with substantial statistical heterogeneity. The search yielded 1254 articles, and 36 studies were included in our analysis. Meta-analysis of proportions revealed that 1-year, 3-year, and 5-year OS was 100%, 94%, and 88%, while 1-year, 3-year and 5-year DFS was 99%, 89%, and 79%, respectively. An R0 resection rate of 89% and a disease response rate of 67% was achieved after a mean duration of treatment of 8.41±0.367months. KIT exon 9 mutation was significantly associated with poorer 5-year DFS. This study quantified key outcomes for neoadjuvant imatinib in locally advanced and metastatic or recurrent GIST. Patients with gastric and rectal tumous stand to benefit from neoadjuvant imatinib with an optimal treatment duration of 8months. Furthermore, the potential utility of mutational analysis in guiding treatment with neoadjuvant imatinib was demonstrated.

Gastrointestinal stromal tumor(GIST) is the most common mesenchymal tumor in the gastrointestinal tract. Due to the occult onset, GIST may present as local advanced or with metastatic disease at diagnosis. Imatinib mesylate (IM) has effectively improved the prognosis of GIST patients and has been established as principle therapy in metastatic GIST. The role of IM as an adjunction to surgery in the management of high-risk and local advanced GIST is also highly regarded. The role of surgery in metastatic or recurrent GIST is still a controversial clinic problem. For local advanced GIST or GIST in the unfavorable anatomic site(e.g. esophagogastric junction, duodenum, and rectum), based on the limited evidence, surgery may have potential benefits as conversion therapy. Surgery may have a limited favorable impact on progression-free survival and overall survival for those patients whose disease is responding to imatinib or those with limited focal progression. Patients with extensive advanced relapse metastatic GIST or imatinib-resistant disease should not undergo surgery unless emergency situation or complication occurs, where palliative intervention may be justified.

Surgical resection of gastrointestinal stromal tumors (GISTs) has been the most effective therapy for these rare tumors. Imatinib has been introduced as systemic therapy for locally advanced and metastatic GIST. In this study, the surgical resection rates and long-term outcomes of patients treated with preoperative imatinib for locally advanced primary, recurrent, or metastatic GISTs were evaluated. Patients were retrospectively assessed for completeness of surgical resection and for disease-free and overall survival after resection. Forty-six patients underwent surgery after treatment with imatinib. Eleven were treated for locally advanced primary GISTs for a median of 11.9 months, followed by complete surgical resection. All eleven were alive at a median of 19.5 months, and ten were free of disease. Thirty-five patients were treated for recurrent or metastatic GIST. Of these, eleven underwent complete resection. Six of the eleven patients had recurrent disease at a median of 15.1 months. All eleven patients were alive at a median of 30.7 months. Patients with a partial radiographic tumor response to imatinib had significantly higher complete resection rates than patients with progressive disease (91% vs. 4%; P < .001). Of the 24 patients with incomplete resection, 18 initially responded to imatinib but were unable to undergo complete resection after they progressed before surgery. Preoperative imatinib can decrease tumor volume and is associated with complete surgical resection in locally advanced primary GISTs. Early surgical intervention should be considered for imatinib-responsive recurrent or metastatic GIST, since complete resection is rarely achieved once tumor progression occurs.

Effective therapy for advanced gastrointestinal stromal tumors

1511P - Surgery in the treatment of metastatic and recurrent Gastrointestinal Stromal Tumors

Objective: To investigate the clinicopathological features of gastrointestinal stromal tumor (GIST) with KIT/PDGFRA "homozygous mutation", the efficacy of targeted therapy and the prognosis. Methods: A retrospective cohort study and propensity score matching were used. "Homozygous mutation" was defined as the detection of KIT/PDGFRA gene status of GIST by Sanger sequencing, which showed that there was only mutant gene sequence in the sequencing map, lack of wild-type sequence or the peak height of mutant gene sequence was much higher than that of wild-type gene sequence (> 3 times). "Heterozygous mutation" was defined as the mutant gene sequences coexisted with wild type gene sequences, and the peak height was similar (3 times or less). The clinicopathological data and follow-up information of 92 GIST patients with KIT/PDGFRA "homozygous mutation" were collected from 4 hospitals in Shanghai from January 2008 to May 2021 (Renji Hospital, Shanghai Jiaotong University School of Medicine: 70 cases; Zhongshan Hospital, Fudan University: 14 cases; Changhai Hospital, Naval Military Medical University: 6 cases and Ruijin Hospital, Shanghai Jiaotong University School of Medicine: 2 cases). Patients with perioperative death, other malignancies, and incomplete clinicopathological information were excluded. The clinicopathological features of the patients and the efficacy of targeted drug therapy were observed and analyzed. The efficacy was evaluated using Choi criteria, which were divided into complete response (CR), partial response (PR), stable disease (SD) and progressive disease (PD). In addition, a total of 230 patients with high-risk GIST with "heterozygous mutation" in exon 11 of KIT gene and 117 patients with recurrent or metastatic GIST with "heterozygous mutation" in exon 11 of KIT gene were included. The propensity score matching method was used to match GIST patients with "heterozygous" and "homozygous" mutations in exon 11 of KIT gene (1∶1) for survival analysis. The disease-free survival (DFS) between two groups of high-risk GIST patients who underwent complete surgical resection were compared. And progression-free survival (PFS) in patients with recurrent or metastatic GIST were compared. Results: Of the 92 GIST cases with KIT/PDGFRA "homozygous mutation", 58 were males and 34 were females, with a median onset age of 62 (31-91) years. Primary GIST 83 cases. Primary high-risk GIST (53 cases), metastatic GIST (21 cases) and recurrent GIST (9 cases) accounted for 90.2% (83/92). There were 90 cases of KIT gene"homozygous mutation" (exon 11 for 88 cases, exon 13 for 1 case, exon 17 for 1 case), and 2 cases of PDGFRA gene "homozygous mutation" (exon 12 for 1 case, exon 18 for 1 case). The median follow-up time was 49 (8-181) months. Among the 61 cases of primary localized GIST undergoing complete surgical resection, 2 cases were intermediate-risk GIST, 5 cases were low-risk GIST, and 1 case was very low-risk GIST, of whom 1 case of intermediate-risk GIST received 1-year adjuvant imatinib mesylate (IM) therapy after operation, and no tumor recurrence developed during the follow-up period. The remaining 53 cases were high-risk GIST, and follow-up data were obtained from 50 cases, of whom 22 developed tumor recurrence during follow-up. Of 9 patients directly receiving neoadjuvant targeted therapy (IM or avapritinib), 5 had complete imaging follow-up data, and the evaluation of efficacy achieved PR. Of all the 92 GIST cases with KIT/PDGFRA "homozygous mutation", 50 (54.4%) had tumor metastasis or tumor recurrence or progression during follow-up, and 12 (13.0%) died of the tumor. Survival analysis combined with propensity score showed that in 100 cases of high-risk GISTs with complete resection, GISTs with "homozygous mutation" in exon 11 of KIT gene had shorter disease-free survival (DFS) than GISTs with "heterozygous mutation" in exon 11 of KIT gene (median DFS: 72 months vs. 148 months, P=0.015). In 60 cases of recurrent or metastatic GISTs with KIT gene exon 11 mutation, IM was used as the first-line treatment, and the progression-free survival (PFS) of GISTs with "homozygous mutation" was shorter compared to GISTs with "heterozygous mutation" (median PFS: 38 months vs. 69 months, P=0.044). The differences were statistically significant. Conclusions: "Homozygous mutation" in KIT/PDGFRA gene is associated with the progression of GIST. The corresponding targeted therapeutic drugs are still effective for GIST with KIT/PDGFRA gene "homozygous mutation". Compared with GIST patients with "heterozygous mutation" in KIT exon 11, GIST patients with "homozygous mutation" in KIT exon 11 are more likely to relapse after surgery and to develop resistance to IM. Therefore, it is still necessary to seek more effective treatment methods for this subset of cases.

BackgroundImatinib mesylate has been the standard therapeutic treatment for chronic myeloid leukemia, advanced and metastatic gastrointestinal stromal tumor (GIST). It is well tolerated with mild adverse effects. Gynecomastia development during the course of treatment has been rarely reported.MethodsNinety-eight patients with advanced or recurrent GIST were treated with imatinib mesylate. Among the fifty-seven male patients six developed gynecomastia during the treatment. The lesions were confirmed by sonography. Sex hormone levels were determined in six patients with and without the presence of gynecomastia respectively. The patients with gynecomatia were treated with tamoxifene and the sex hormones were assayed before and after tamoxifene treatment.ResultsIn patients with gynecomastia the lump underneath the bilateral nipples was 2.5 to 5 centimeters in diameter. Their serum free testosterone levels ranged between 356.61 and 574.60 ng/dl with a mean ± SD of 408.64 ± 82.06 ng/dl (95% CI 343.03~474.25 ng/dl), which is within the normal range. The level of serum estradiol was 42.89 ± 16.54 pg/ml (95% CI 29.66~56.12 pg/ml). Three patients had higher levels (43.79~71.21 pg/ml) and the others' were within normal range of 27.00~34.91 pg/ml. Six patients without the development of gynecomastia had normal free testosterone. One patient died because of large tumor burden. The sex hormones had no significant changes before and after tamoxifene treatment.(P > 0.05)ConclusionsTestosterone levels were not decreased in the six GIST patients with gynecomastia. Three patients had increased serum estradiol level which suggests that imbalance of sex hormones may be the cause of gynecomastia during treatment with imatinib mesylate.

In patients with localized gastrointestinal stromal tumors, surgery remains the elective treatment. Nowadays, imatinib therapy has been standardized in advanced gastrointestinal stromal tumors, showing continuous improvements in progression-free and overall survival. A combination of imatinib therapy and surgery may also be effective in a subset of patients with metastatic or unresectable gastrointestinal stromal tumors. In this review, the authors analyzed the role of imatinib mesylate associated to surgery in unresectable and/or metastatic gastrointestinal stromal tumors. We searched for all published and unpublished randomized controlled clinical trials and controlled clinical trials. We conducted the review according to the recommendations of The Cochrane Collaboration. We used Review Manager 5 software for the statistical analysis. There are currently no randomized controlled clinical trials or controlled clinical trials on this issue. We performed a subgroup analysis in the patients preoperatively treated with imatinib mesylate. This subgroup revealed a minor incidence of recurrent or metastatic gastrointestinal stromal tumors and a greater incidence of locally unresectable gastrointestinal stromal tumors in the responsive disease group (P = 0.001). In this patient group, more complete resections were observed (P = 0.00001). Furthermore, in the same patient group we observed a more significant 12 and 24-month disease-free survival after imatinib treatment and complete resection (respectively P= 0.06 and P= 0.003) and also a better 24-month overall survival (P = 0.004). There is actually only one ongoing European randomized study evaluating surgery of residual disease in patients with metastatic gastrointestinal stromal tumors responding to imatinib mesylate. Imatinib mesylate represents the standard treatment as preoperative supplement for locally unresectable and/or metastatic gastrointestinal stromal tumors, and a trial to compare the approach versus surgery alone is not necessary. For patients responding to imatinib or patients with prolonged stable disease, resection of residual disease should be considered. A phase III randomized study evaluating surgery of residual disease in patients with metastatic gastrointestinal stromal tumor responding to imatinib mesylate, EORTC 62063, has been opened. Moreover, surgery should be considered for patients at higher risk of complications during pharmacological debulking. In advanced gastrointestinal stromal tumors, the advantages of the integrated treatment are significant in the complete or partial response disease group in terms of more complete resections and better disease-free and overall survival.

In patients with localized gastrointestinal stromal tumors, surgery remains the elective treatment. Nowadays, imatinib therapy has been standardized in advanced gastrointestinal stromal tumors, showing continuous improvements in progression-free and overall survival. A combination of imatinib therapy and surgery may also be effective in a subset of patients with metastatic or unresectable gastrointestinal stromal tumors. In this review, the authors analyzed the role of imatinib mesylate associated to surgery in unresectable and/or metastatic gastrointestinal stromal tumors. We searched for all published and unpublished randomized controlled clinical trials and controlled clinical trials. We conducted the review according to the recommendations of The Cochrane Collaboration. We used Review Manager 5 software for the statistical analysis. There are currently no randomized controlled clinical trials or controlled clinical trials on this issue. We performed a subgroup analysis in the patients preoperatively treated with imatinib mesylate. This subgroup revealed a minor incidence of recurrent or metastatic gastrointestinal stromal tumors and a greater incidence of locally unresectable gastrointestinal stromal tumors in the responsive disease group (P = 0.001). In this patient group, more complete resections were observed (P = 0.00001). Furthermore, in the same patient group we observed a more significant 12 and 24-month disease-free survival after imatinib treatment and complete resection (respectively P= 0.06 and P= 0.003) and also a better 24-month overall survival (P = 0.004). There is actually only one ongoing European randomized study evaluating surgery of residual disease in patients with metastatic gastrointestinal stromal tumors responding to imatinib mesylate. Imatinib mesylate represents the standard treatment as preoperative supplement for locally unresectable and/or metastatic gastrointestinal stromal tumors, and a trial to compare the approach versus surgery alone is not necessary. For patients responding to imatinib or patients with prolonged stable disease, resection of residual disease should be considered. A phase III randomized study evaluating surgery of residual disease in patients with metastatic gastrointestinal stromal tumor responding to imatinib mesylate, EORTC 62063, has been opened. Moreover, surgery should be considered for patients at higher risk of complications during pharmacological debulking. In advanced gastrointestinal stromal tumors, the advantages of the integrated treatment are significant in the complete or partial response disease group in terms of more complete resections and better disease-free and overall survival.

BackgroundThe role of surgery in the management of patients with advanced gastrointestinal stromal tumors (GIST) in the era of imatinib mesylate (IM) remains debated. We analyzed the outcome of patients with non metastatic locally advanced primary GIST treated with IM within the prospective BFR14 phase III trial.MethodsThe database of the BFR14 trial was searched for patients with no metastasis at time of inclusion. Patients treated for recurrent disease were excluded. Twenty-five of 434 patients met these criteria.ResultsFifteen of 25 patients (60%) had a partial response to IM. Nine of the 25 patients (36%) underwent surgical resection of their primary tumor after a median of 7.3 months of IM treatment (range 3.4-12.0). Per protocol patients received continuous IM treatment in the post resection period, in an adjuvant setting. With a median follow-up of 53.5 months, there was a significant improvement in progression-free survival (PFS) and overall survival (OS) for patients who underwent surgical resection versus those who did not (median not reached vs 23.6 months, p = 0.0318 for PFS and median not reached vs 42.2 months, p = 0.0217 for OS). In the group of patients who underwent resection followed by IM, the 3-year PFS and OS rates were 67% and 89% respectivelyConclusionsFollowing neoadjuvant IM for non metastatic locally advanced GIST 9 of 25 patients (36%) were selected for resection of the primary tumor. OS and PFS figures were close to those of localised intermediate or high risk GIST (70% at 5 years) in the subgroup of operated patients, while the outcome of the non-operated subgroup was similar to that of metastatic GIST.

In the treatment of recurrent or metastatic gastrointestinal stromal tumors (GIST), good prognoses may not be expected by surgery alone. Recently, imatinib has been applied for the treatment of GISTs, resulting in improved patient survival. However, long-term success is limited due to the development of resistance. Herein, we report two cases of long-surviving patients with recurrent GIST after receiving cytoreductive surgery with imatinib therapy. A 49 year-old man was diagnosed to a duodenal GIST with single hepatic metastasis, and an antrectomy including the duodenal lesion with intraoperative radiofrequency ablation were performed in April, 2002. After four months, a new metastatic hepatic lesion was identified. Percutaneous radiofrequency ablation was done, and imatinib therapy was started. A 56 year-old man underwent laparoscopic segmental resection of the distal ileum and partial excision of parietal peritoneum in March, 2001 to treat a malignant GIST of the distal ileum that was attached to parietal peritoneum. After six months, recurrence of GIST with peritoneal seeding and hepatic metastasis was found, and he underwent cytoreductive surgery including right hemicolectomy and wedge resection of liver. After surgery, there was no residual tumor grossly and imatinib therapy was started. In both cases, they were doing well with no evidence of recurrence for 5 years with imatinib therapy. Therefore, in patients with a recurrent GIST, improved survival can be expected with imatinib therapy after cytoreductive surgery.