Current and emerging therapeutic strategies in pancreatic cancer: Challenges and opportunities

Pancreatic carcinoma (PC) is one of the leading causes of cancer-related deaths worldwide. Despite early detection and advances in therapeutics, the prognosis remains dismal. The outcome and therapeutic approach are dependent on the stage of PC at the time of diagnosis. The standard of care is surgery, followed by adjuvant chemotherapy. The advent of newer drugs has changed the landscape of adjuvant therapy. Moreover, recent trials have highlighted the role of neoadjuvant therapy and chemoradiotherapy for resectable and borderline resectable PC. As we progress towards a better understanding of tumor biology, genetics, and microenvironment, novel therapeutic strategies and targeted agents are now on the horizon. We have described the current and emerging therapeutic strategies in PC.

Impact of completeness of adjuvant gemcitabine, relapse pattern, and subsequent therapy on outcome of patients with resected pancreatic ductal adenocarcinoma - A pooled analysis of CONKO-001, CONKO-005, and CONKO-006 trials

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) represents one of the most fatal malignancies worldwide. It is suggested that survival in PDAC depends, among other things, on pattern of disease recurrence.

PATIENTS AND METHODS

We performed a pooled analysis of the adjuvant therapy studies CONKO-001, CONKO-005, and CONKO-006, including a total of 912 patients with regard to prognostic factors in patients with recurrent disease. Overall survival from disease recurrence (OS 2) and disease-free survival (DFS) from the day of surgery were expressed by Kaplan-Meier method and compared using log-rank testing and Cox regression.

RESULTS

Of 912 patients treated within the previously mentioned CONKO trials, we identified 689 patients with disease recurrence and defined site of relapse. In multivariable analysis, the presence of isolated pulmonary metastasis, low tumour grading, and low postoperative level of CA 19-9 remained significant factors for improved OS 2 and DFS. Furthermore, completeness of adjuvant gemcitabine-based treatment (OS 2: P = 0.006), number of relapse sites (OS 2: P = 0.015), and type of palliative first-line treatment (OS 2: P < 0.001) significantly affected overall survival after disease recurrence in PDAC.

CONCLUSIONS

Determining tumour subgroups using prognostic factors may be helpful to stratify PDAC patients for future clinical trials. In case of disease recurrence, the site of relapse may have a prognostic impact on subsequent survival. Further investigations are needed to identify differences in tumour biology, reflecting relapse patterns and the differing survival of PDAC patients.

Adjuvant treatment of pancreatic cancer

PURPOSE OF REVIEW

Pancreatic cancer will soon become one of the most common causes of cancer death. Early detection of pancreatic cancer remains impossible and only 20% of patients are suitable for surgery once diagnosed. Even in this specific subgroup of patients, and despite improvements in surgery, overall survival remains poor, with an 80% recurrence rate. Consequently, many attempts have been made to prevent recurrence by adding chemotherapy, radiotherapy, or both.

RECENT FINDINGS

Here, we will focus on results of randomized trials evaluating the role of different postoperative treatments. Over 15 years ago, a trial demonstrated that chemoradiotherapy has a deleterious effect on survival. The same trial recommended adjuvant chemotherapy with fluorouracil as standard of care. Subsequent trials sought to identify better chemotherapy regimens. Two recently published trials evaluated the role of combination therapies for resected pancreatic cancer and demonstrated better outcomes with a gemcitabine and capecitabine combination and a fluorouracil, oxaliplatin, and irinotecan combination (FOLFIRINOX) versus gemcitabine alone.

SUMMARY

Results from recent trials suggest that FOLFIRINOX should be considered standard of care for fit patients.

TG01/GM-CSF and adjuvant gemcitabine in patients with resected RAS-mutant adenocarcinoma of the pancreas (CT TG01-01): a single-arm, phase 1/2 trial

BACKGROUND

TG01 is the first cancer immunotherapy targeting KRAS oncogenic mutations. This study assessed the safety and efficacy of TG01/GM-CSF in patients with resected pancreatic adenocarcinoma.

METHODS

Patients with stage I or II pancreatic adenocarcinoma who had undergone surgical resection (R0 or R1) received adjuvant gemcitabine with TG01/GM-CSF using two schedules of vaccination. Immune response was defined as a positive delayed-type hypersensitivity (DTH) response and/or positive T-cell proliferation assay.

RESULTS

Thirty-two patients were enrolled between February 2013 and May 2016. Nineteen were treated with the high antigen burden, with four serious adverse reactions considered possibly related to TG01 treatment, including three allergic reactions. On this basis, a further 13 patients received a modified vaccination schedule with reduced antigen burden, with no serious adverse events related to TG01. Ninety-five percent patients in the main cohort and 92% in the modified cohort had a positive immune response. Median overall survival (OS) was 33.1 months, and median disease-free survival (DFS) was 13.9 months for the main cohort. For the modified cohort, the median OS was 34.3 months and median DFS was 19.5 months.

CONCLUSIONS

TG01/GM-CSF with gemcitabine was well tolerated, with high levels of immune activation. OS and DFS compare favourably with published data for adjuvant gemcitabine.

CLINICAL TRIAL REGISTRATION

This clinical trial was registered at ClinicalTrials.gov (NCT02261714).

Is There a Standard Adjuvant Therapy for Resected Pancreatic Cancer?

Surgical resection remains the only treatment that offers a potential chance of long-term survival. Unfortunately, about 80% of patients treated with curative intent will develop recurrence. Since 2001, adjuvant therapy with gemcitabine or 5-fluorouracyle was recommended. This approach allows a median overall survival (OS) of around 23 months, and 5-year survival of 22%. In recent years, two phase-3 trials investigating new chemotherapy regimens resulted in considerably improved survival times. The doublet gemcitabine-capecitabine has shown improvement in OS from 25.5 to 28 months (p = 0.032) compared to gemcitabine, in the ESPAC-4 trial. Later, preliminary results of PRODIGE 24 trial presented at the 2018 ASCO meeting showed a superiority of a combination chemotherapy regimen with fluorouracil, leucovorin, irinotecan, and oxaliplatin (mFOLFIRINOX) when compared to gemcitabine alone, both in terms of median disease-free survival (21.6 vs. 12.8 months, p < 0.0001) and OS (54.4 vs. 35 months, p = 0.003). Contrary to chemotherapy, the role of adjuvant radiotherapy is still controversial, even in the case of R1 surgery. A randomized trial exploring the role of chemoradiotherapy in this setting is now ongoing in the US (RTOG-0848). Overall, the management of localized pancreatic adenocarcinoma is evolving. In this review, we summarize the current status and the most up-to-date developments in adjuvant treatment.

An update on treatment options for pancreatic adenocarcinoma

Pancreatic cancer is one of the most lethal solid organ tumors. Due to the rising incidence, late diagnosis, and limited treatment options, it is expected to be the second leading cause of cancer deaths in high income countries in the next decade. The multidisciplinary treatment of this disease depends on the stage of cancer at diagnosis (resectable, borderline, locally advanced, and metastatic disease), and combines surgery, chemotherapy, chemoradiotherapy, and supportive care. The landscape of multidisciplinary pancreatic cancer treatment is changing rapidly, especially in locally advanced disease, and the number of treatment options in metastatic disease, including personalized medicine, innovative targets, immunotherapy, therapeutic vaccines, adoptive T-cell transfer, or stemness inhibitors, will probably expand in the near future. This review summarizes the current literature and provides an overview of how new therapies or new therapeutic strategies (neoadjuvant therapies, conversion surgery) will guide multidisciplinary disease management, future clinical trials, and, hopefully, will increase overall survival.

Chemotherapy for pancreatic cancer

Chemotherapy is an important part of multimodality pancreatic cancer treatment. After curative resection, adjuvant chemotherapy can significantly improve disease free survival and overall survival. The current standard of care is six months adjuvant chemotherapy with modified folinic acid, 5-fluorouracil, irinotecan and oxaliplatin (mFOLFIRINOX) in patients fit enough for this protocol, otherwise six months of gemcitabine and capecitabine based on the European Study Group for Pancreatic Cancer (ESPAC)-4 study. In patients with metastatic disease, combination chemotherapy according to the FOLFIRINOX protocol or with gemcitabine plus nab-paclitaxel is an important improvement to gemcitabine monotherapy that was the standard for many years. Patients not fit for combination chemotherapy however may still benefit from gemcitabine. Patients with good performance status may benefit from second-line chemotherapy. Chemoradiation has long been used in locally advanced pancreatic cancer but is now tempered following the LAP07 study. This trial showed no difference in overall survival in those patients with stable disease after four months of gemcitabine (with or without erlotinib) randomized to either continuation of gemcitabine therapy or chemoradiation (54Gy with capecitabine). As an alternative to radiation, other forms local therapies including radiofrequency ablation, irreversible electroporation, high-intensity focused ultrasound, microwave ablation and local anti-KRAS therapy (using siG12D-LODER) are currently under investigation. Given the systemic nature of pancreas cancer from an early stage, the success of any local approach other than complete surgical resection (with adjuvant systemic therapy) is likely to be very limited. In patients with locally advanced, irresectable cancer, chemotherapy may offer the chance for secondary resection with a survival similar to patients with primary resectable disease. Downstaging regimens need to be evaluated in prospective randomized trials in order to make firm recommendations. Selection of patient groups for specific therapy including cytotoxics is becoming a reality using assays based on drug cellular transport and metabolism, and molecular signatures. Going forward, high throughput screening of different chemotherapy agents using molecular signatures based on patients' derived organoids holds considerable promise.

FOLFIRINOX or Gemcitabine as Adjuvant Therapy for Pancreatic Cancer

BACKGROUND

Among patients with metastatic pancreatic cancer, combination chemotherapy with fluorouracil, leucovorin, irinotecan, and oxaliplatin (FOLFIRINOX) leads to longer overall survival than gemcitabine therapy. We compared the efficacy and safety of a modified FOLFIRINOX regimen with gemcitabine as adjuvant therapy in patients with resected pancreatic cancer.

METHODS

We randomly assigned 493 patients with resected pancreatic ductal adenocarcinoma to receive a modified FOLFIRINOX regimen (oxaliplatin [85 mg per square meter of body-surface area], irinotecan [180 mg per square meter, reduced to 150 mg per square meter after a protocol-specified safety analysis], leucovorin [400 mg per square meter], and fluorouracil [2400 mg per square meter] every 2 weeks) or gemcitabine (1000 mg per square meter on days 1, 8, and 15 every 4 weeks) for 24 weeks. The primary end point was disease-free survival. Secondary end points included overall survival and safety.

RESULTS

At a median follow-up of 33.6 months, the median disease-free survival was 21.6 months in the modified-FOLFIRINOX group and 12.8 months in the gemcitabine group (stratified hazard ratio for cancer-related event, second cancer, or death, 0.58; 95% confidence interval [CI], 0.46 to 0.73; P<0.001). The disease-free survival rate at 3 years was 39.7% in the modified-FOLFIRINOX group and 21.4% in the gemcitabine group. The median overall survival was 54.4 months in the modified-FOLFIRINOX group and 35.0 months in the gemcitabine group (stratified hazard ratio for death, 0.64; 95% CI, 0.48 to 0.86; P=0.003). The overall survival rate at 3 years was 63.4% in the modified-FOLFIRINOX group and 48.6% in the gemcitabine group. Adverse events of grade 3 or 4 occurred in 75.9% of the patients in the modified-FOLFIRINOX group and in 52.9% of those in the gemcitabine group. One patient in the gemcitabine group died from toxic effects (interstitial pneumonitis).

CONCLUSIONS

Adjuvant therapy with a modified FOLFIRINOX regimen led to significantly longer survival than gemcitabine among patients with resected pancreatic cancer, at the expense of a higher incidence of toxic effects. (Funded by R&D Unicancer and others; ClinicalTrials.gov number, NCT01526135 ; EudraCT number, 2011-002026-52 .).

CONKO-005: Adjuvant Chemotherapy With Gemcitabine Plus Erlotinib Versus Gemcitabine Alone in Patients After R0 Resection of Pancreatic Cancer: A Multicenter Randomized Phase III Trial

Purpose Gemcitabine is standard of care in the adjuvant treatment of resectable pancreatic ductal adenocarcinoma (PDAC). The epidermal growth factor receptor tyrosine kinase inhibitor erlotinib in combination with gemcitabine has shown efficacy in the treatment of advanced PDAC and was considered to improve survival in patients with primarily resectable PDAC after R0 resection. Patients and Methods In an open-label, multicenter trial, patients were randomly assigned to one of two study arms: gemcitabine 1,000 mg/m² days 1, 8, 15, every 4 weeks plus erlotinib 100 mg once per day (GemErlo) or gemcitabine (Gem) alone for six cycles. The primary end point of the study was to improve disease-free survival (DFS) from 14 to 18 months by adding erlotinib to gemcitabine. Results In all, 436 patients were randomly assigned at 57 study centers between April 2008 and July 2013. A total of 361 instances (83%) of disease recurrence were observed after a median follow-up of 54 months. Median treatment duration was 22 weeks in both arms. There was no difference in median DFS (GemErlo 11.4 months; Gem 11.4 months) or median overall survival (GemErlo 24.5 months; Gem 26.5 months). There was a trend toward long-term survival in favor of GemErlo (estimated survival after 1, 2, and 5 years for GemErlo was 77%, 53%, and 25% v 79%, 54%, and 20% for Gem, respectively). The occurrence or the grade of rash was not associated with a better survival in the GemErlo arm. Conclusion To the best of our knowledge, CONKO-005 is the first study to investigate the combination of chemotherapy and a targeted therapy in the adjuvant treatment of PDAC. GemErlo for 24 weeks did not improve DFS or overall survival over Gem.