Comparison of the effectiveness of integrative immunomodulatory treatments and conventional therapies on the survival of selected gastrointestinal cancer patients

In the last decade, the use of immunomodulating treatments (IMT) at integrative oncology providers (IOP) increased. IMTs are used to modulate the tumor microenvironment, which might lead to increased response-to-treatment, and the indication of immune checkpoint inhibitors might also be widened. The efficacy and safety of IMTs in advanced/metastatic gastrointestinal cancers were compared with conventional chemo(radio)therapy (CT). 21 colorectal– (CRC), 14 pancreatic– (PC), 5 cholangiocellular– (CCC), 5 gastric– (GC) and 4 esophageal cancer (EC) patients received IMT. IMT and CT were compared in CRC and PC. CT was administered at an academic oncology center. After the initiation of IMT, a median survival of ~ 20 (CRC, PC and EC) and ~ 10 months (CCC and GC) was observed. Of the IMTs, locoregional modulated electro-hyperthermia had the most positive effect on overall survival (HR: 0.3055; P = 0.0260), while fever-inducing interleukin-2, and low-dose ipilimumab showed a positive tendency. IMT was superior to CT in PC (HR: 0.1974; P = 0.0013), while modest effect was detected in CRC (HR: 0.7797; P = 0.4710). When the whole study population was analyzed, IMTs showed minimal effect on patient survival, still CT had the greatest effect if introduced as early as possible (HR: 0.0624; P < 0.0001). The integrative IMTs in the presented form have mild impact on gastrointestinal cancer patients’ survival, however, we observed its benefit in PC, which warrants further investigations.


Literature data about the potential immunomodulators
Based on in vitro and animal model data, artesunate, curcumin, dichloroacetate, high-dose vitamin C, interferon-γ, and interleukin-2 have known anti-tumor effects.Without going into details, they can induce apoptosis or ferroptosis, inhibit tumor cell growth, suppress angiogenesis, inflammation and oxidative stress, reverse drug resistance, downregulate immunosuppression, and induce immune cell activity against cancer cells 1-7 .Moreover, it has been reported that a high dose of vitamin C in combination with anti-PD-1 checkpoint inhibition can increase cytotoxic T cell and NK cell activity in a lymphoma mouse model 8 .However, despite the wide knowledge regarding the effects of these treatment options on cancer cells and animal models, clinical study results are extremely limited, and largely only a single agent was used rather than any combinations.
Artesunate has been investigated in colorectal cancer (CRC) only: In a small-sized randomized trial, after a two-week pre-operative treatment with daily 200 mg per os artesunate, decreased Ki67 activity of the tumor has been found, and less recurrence has occurred compared to that of the placebo group (1 vs. 6) 9 .Similarly, a single study of CRC patients is available only in the case of interferon-γ, where it was concomitantly used with fluorouracil (5-FU) and interferonα resulting in improved response rates, but with an increased 5-FU clearance 10 .Moreover, a limited number of data is available on dichloroacetate: 1-1 cholangiocellular cancer (CCC) 11 , CRC 12 , and gastric cancer (GC) 13 cases with prolonged stable disease after the introduction of dichloroacetate have been reported.No clinical results on gastrointestinal tumors could be found about ozone therapy 14 .
Curcumin has been tested recently as a possible candidate in preventing the development of CRC 15,16 , it is safe and well-tolerated by CRC patients [17][18][19][20] , and it is able to reduce the sideeffects of chemo(radio)therapy and improve patient's QoL 21,22 .Overall survival of metastatic CRC patients receiving FOLFOX (folinic acid + 5-FU + oxaliplatin) plus daily 2 g oral curcumin has improved, compared to those having FOLFOX only, without any difference in the progression-free survival 20 .It has to be noted that in another study 17 , no difference in tumor response could be found.Moreover, curcumin has been found to be a potential booster for more effective immunotherapy 15 , and there are a few randomized trials currently running, of which the results are eagerly awaited 16,23 .In pancreatic cancer (PC), poor bioavailability, even for the high, daily 12 g oral dose, and a high rate of serious adverse events caused by curcumin could have been reported 24,25 .The introduction of nanoparticle-coupled curcumin called Theracurmin® and other newer curcumin analogs have shown more promising results [24][25][26] , but the biological efficacy of curcumin is still low and the available clinical data is still scarce 27 .
The same applies to GC: to date, no effective form of curcumin could have been found 28 , and there is no clinical data on esophageal cancer (EC) 29 and CCC.
In the early '90sincluding but not limited to the studies of Akiyoshi et al. 30 , Atzpodien et al. 31,32 , de Braud et al. 33 , Lygidakis et al. 34 , and Ridolfi et al. 35 -, subcutaneous and intravenous interleukin-2 have been tested in combination with standard chemotherapy regimens showing little improvements compared to treatments without interleukin-2.Later, in advanced and/or metastatic CRC, phase II and III studies investigated the efficacy and safety of the GOLFIG (gemcitabine + oxaliplatin + folinic acid + 5-FU followed by subcutaneous granulocytemacrophage colony-stimulating factor + interleukin-2) [36][37][38] and the GILFICet (gemcitabine + irinotecan + folinic acid + 5-FU + cetuximab followed by subcutaneous interleukin-2) 39 chemoimmunotherapy regimens, and have found improved long-term progression-free survival, overall survival 36,37 and the treatment-related immunogenicity has been associated with increased antitumor activity 38,39 .A similar observation was confirmed in PC: neo-and adjuvant chemoimmunotherapy (gemcitabine + carboplatin + mitoxantrone + interleukin-2 + interferon-γ) 40,41 in combination with resective or palliative surgery have resulted in better and long-lasting response to treatment 41 and prolonged survival of patients for both types of surgery, compared to those with surgery alone 40,41 .
High-dose vitamin C can reduce the inflammation in cancer patients 42 , and its effect in combination with standard chemotherapy on CRC [43][44][45][46] , PC [46][47][48][49] , and GC 43 have been investigated in randomized trials.In a phase I study it was found that in terminal cancer patients disease progression had occurred on average after 8 weeks when administering a daily dose of 150 to 710 mg/kg vitamin C 50 .In advanced and metastatic CRC patients, no difference in response rates, overall-, and progression-free survival could have been justified [43][44][45] .In contrast, patients with RAS mutation have had better survival results if treated with high-dose vitamin C + FOLFOX with or without bevacizumab 44 .In metastatic PC, in combination with gemcitabine and erlotinib, the high-dose vitamin C treatment could have reduced the size of the tumor 47 , and in combination with gemcitabine 3 months and 13 -15.1 months progression-free and overall median survival have been reported, respectively 48,49 .
The United States Food and Drug Administration (FDA) approved the use of 3 mg/kg nivolumab (normal dose) plus 1 mg/kg ipilimumab (low-dose) in CRC and in renal cancer, while a reversed dosing (1 mg/kg nivolumab + 3 mg/kg ipilimumab) was allowed for melanoma and hepatocellular carcinoma 51 .However, to date, the use of low-dose nivolumab (0.5 mg/kg) in combination with low-dose ipilimumab (0.3 mg/kg) in the routine conventional oncological practice of any cancer is uncommon 51,52 .Some data are available from a limited number of phase I and II randomized clinical trials and from observational studies [51][52][53][54] : lower doses have been reported to have less toxicity, but the efficacy of the reduced doses is largely unknown.In vitro, animal models, and a few clinical studies have suggested that curcumin 55 , dichloroacetate 56 , high dose vitamin C 8,54,57 , hyperthermia 54,58 , interferon-γ 59 , and interleukin-2 5,54,60 can/may increase the antitumor effects of ICIs, therefore, conducting randomized trials on the subject is urgently needed.
Studies investigating metronomic chemotherapy in gastrointestinal cancers have significantly emerged in recent years 61,62 .Although the toxicity of chemotherapeutic drugs improves during metronomic chemotherapy 61,62 , the results of clinical studies are controversial.The most promising results have been found in PC 61,63 , while the data on GC and EC is not conclusive 61,64 .
In CRC, progression-free survival usually improves but no improvement in overall survival could have been justified 61,62,65 , and there is virtually no data about CCC 61 .Similar to that of low-dose ICIs, randomized trials are required to fully investigate the effectiveness of metronomic chemotherapy in these tumors.Whole-body hyperthermia (WBH) was investigated among the earliest studies of oncologic hyperthermia 66,67 .In most early studies, the number of cases was low, results have shown that WBH is a safe and effective treatment option 67 , which can also improve the quality of life of patients 67,68 , but in several cases, populations with mixed tumors were analyzed [68][69][70][71][72] .In addition to the improved disease response 73 , WBH can prolong pain control for a longer duration in CRC/rectal cancer 74 .Moreover, post-treatment carcinoembryonic antigen (CEA) can be significantly lowered one month after WBH treatment in combination with 131 I anti-CEA monoclonal antibody 75 .Administering WBH preoperatively can improve the postoperative reactions of the immune system 76 , while no conclusive data on systemic cancer multistep therapy (WBH plus induced hyperoxemia and hyperglycemia) could have been justified 77 .
Improved disease response and prolonged survival have been also confirmed in GC 78 and in PC 79 .In the GC article 78 , the authors could have also described improved Karnofsky Performance Status scores, decreasing the size of hepatic metastases, and decreasing the number of abdominal lymph nodes, and reduced rate of ascites development in the treatment arm 78 .
The latest advancement in oncological hyperthermia is mEHT, which was developed later, and most data are available from the last decade 66,67,80 .In the studies of Fiorentini et al. 81,82 , mEHTtreated PC patients had almost twice as long survival compared to those receiving chemotherapy only.This strong observation could not be verified in a previous study conducted by our team 83 .Moreover, mEHT-treated PC patients having no metastasis and/or ascites benefit more from mEHT 83 , and significantly better responses to treatment have also been described previously 81,82 .In addition, our team was able to justify, that the median overall survival time significantly improves in those PC patients, who receive more mEHT treatments, compared to matched non-mEHT treated PC patients 84 .Similar results have been described in three additional studies [85][86][87] , where no comparison to control patients has been performed, but PC patients have had a better response to treatment and longer survival than normally expected 85- 87 .In rectal cancer, preoperative concomitant mEHT has been associated with T-and Ndownstaging [88][89][90][91] but with controversial survival data 90,91 .To our knowledge, only a few studies/case reports are available in CCC 92 , CRC 93 , EC 94 , and GC 95 , all with favorable responses to the treatment.

Table S3
Anamnestic data of pancreatic cancer (PC) patients receiving immunomodulating therapy (IMT), and age, sex, tumor location and metastasis matched PC patients receiving conventional treatment with or without modulated electro-hyperthermia (mEHT).Continuous and count data are presented as the mean ± standard deviation and the number of observations, respectively.

Table S4
p-Values of the comparisons of the anamnestic data of pancreatic cancer (PC) patients receiving immunomodulating therapy (IMT), and age, sex, tumor location and