Molecular Basis of Cancer Pain Management: An Updated Review

A genome-wide association study of European advanced cancer patients treated with opioids identifies regulatory variants on chromosome 20 associated with pain intensity

BACKGROUND

Opioids in step III of the WHO analgesic ladder are the standard of care for treating cancer pain. However, a significant minority of patients do not benefit from therapy. Genetics might play a role in predisposing patients to a good or poor response to opioids. Here, we investigated this issue by conducting a genome-wide association study (GWAS).

METHODS

We genotyped 2057 European advanced cancer patients treated with morphine, buprenorphine, fentanyl and oxycodone. We carried out a whole-genome regression model (using REGENIE software) between genotypes and the opioid response phenotype, defined as a numerical score measuring patient pain intensity.

RESULTS

The GWAS identified five non-coding variants on chromosome 20 with a p-value <5.0 × 10-8. For all of them, the minor allele was associated with lower pain intensity. These variants were intronic to the PCMTD2 gene and were 200 kbp downstream of OPRL1, the opioid related nociceptin receptor 1. Notably according to the eQTLGen database, these variants act as expression quantitative trait loci, modulating the expression mainly of PCMTD2 but also of OPRL1. Variants in the same chromosomal region were recently reported to be significantly associated with pain intensity in a GWAS conducted in subjects with different chronic pain conditions.

CONCLUSIONS

Our results support the role of genetics in the opioid response in advanced cancer patients. Further functional analyses are needed to understand the biological mechanism underlying the observed association and lead to the development of individualized pain treatment plans, ultimately improving the quality of life for cancer patients.

SIGNIFICANCE STATEMENT

This genome-wide association study on European advanced cancer patients treated with opioids identifies novel regulatory variants on chromosome 20 (near PCMTD2 and OPRL1 genes) associated with pain intensity. These findings enhance our understanding of the genetic basis of opioid response, suggesting new potential markers for opioid efficacy. The study is a significant advancement in pharmacogenomics, providing a robust dataset and new insights into the genetic factors influencing pain intensity, which could lead to personalized cancer pain management.

Involvement of CXCL12/CXCR4 in CB2 receptor agonist-attenuated morphine tolerance in Walker 256 tumor-bearing rats with cancer pain

While low-dose cannabinoid 2 (CB2) receptor agonists attenuate morphine tolerance in cancer pain models, chemokine ligand 12 (CXCL12)/chemokine receptor 4 (CXCR4) expression induces morphine tolerance. Whether CB2 receptor agonists attenuate morphine tolerance by modulating CXCL12/CXCR4 signaling or whether CXCL12/CXCR4 signaling affects the mu opioid receptor (MOR) in the development of morphine tolerance in cancer pain remains unclear. In this study, we investigated the attenuation of morphine tolerance by a non-analgesic dose of the CB2 receptor agonist AM1241, focusing specifically on the modulation of CXCL12/CXCR4 signaling and its effect on the MOR. Rats received intrathecal Walker 256 tumor cell implantations and were treated with morphine combined with the intrathecal injection of AM1241 or the CB2 receptor antagonists AM630 and AM1241, or a CXCL12-neutralizing antibody, exogenous CXCL12, or the CXCR4 antagonist AMD3100. Our results show that CXCL12 and CXCR4 levels increased significantly in morphine-tolerant rats and were reduced by AM1241 pretreatment, which was reversed by AM630. CXCL12/CXCR4 expression accelerated the development of morphine tolerance and downregulated MOR expression. CXCR4 colocalized with MOR and CB2. Therefore, a non-analgesic dose of AM1241 attenuated morphine tolerance via CXCL12/CXCR4 signaling, whereas CXCL12/CXCR4 signaling participated in the development of morphine tolerance, potentially by modulating MOR expression in Walker 256 tumor-bearing rats.

Multi-agent Systems and Cancer Pain Management

PURPOSE

The present investigation explores multi-agent systems, their function in cancer pain management, and how they might enhance patient care. Since cancer is a complex disease, technology can help doctors and patients coordinate care and communicate effectively. Even when a patient has a dedicated team, treatment may be fragmented. Multi-agent systems (MAS) are one component of technology that is making progress for cancer patients. Wireless sensory networks (WSN) and body area sensory networks (BASN) are examples of MAS.

RECENT FINDINGS

Technology is advancing the care of patients, not only in everyday clinical practice, but also in creating accessible communication between patients and provider. Many hospitals have utilized electronic medical records (EHR), but recent advancements allowed the pre-existing infrastructure to network with personal devices creating a more congruent form of communications. Better communication can better organize pain management, leading to better clinical outcomes for patients, integrating body sensors, such as smart watch, or using self-reporting apps. Certain software applications are also used to help providers in early detections of some cancers, having accurate results. The integration of technology in the field of cancer management helps create an organized structure for cancer patients trying to understand/manage their complex diagnosis. The systems for the various healthcare entities can receive and access frequently updated information that can better provide better coverage of the patient's pain and still be within the legalities as it pertains to opioid medications. The systems include the EHR communicating with the information provided by the patient's cellular devices and then communicating with the healthcare team to determine the next step in management. This all happens automatically with much physical input from the patient decreasing the amount of effort from the patient and hopefully decreasing the number of patients' loss to follow-up.

Cannabis Pharmacogenomics: A Path to Personalized Medicine

Cannabis and related compounds have created significant research interest as a promising therapy in many disorders. However, the individual therapeutic effects of cannabinoids and the incidence of side effects are still difficult to determine. Pharmacogenomics may provide the answers to many questions and concerns regarding the cannabis/cannabinoid treatment and help us to understand the variability in individual responses and associated risks. Pharmacogenomics research has made meaningful progress in identifying genetic variations that play a critical role in interpatient variability in response to cannabis. This review classifies the current knowledge of pharmacogenomics associated with medical marijuana and related compounds and can assist in improving the outcomes of cannabinoid therapy and to minimize the adverse effects of cannabis use. Specific examples of pharmacogenomics informing pharmacotherapy as a path to personalized medicine are discussed.

Use of oral glutamine in radiation-induced adverse effects in patients with thoracic and upper aerodigestive malignancies: Results of a prospective observational study

Cancer growth in host tissues features glutamine (gln) depletion over time, decreasing epithelial cells' optimal functioning. In addition, radiotherapy (RT) and/or chemotherapy (CT) cause damage to normal tissues, probably enhanced by this depletion. The present study prospectively examined the effect of gln supplementation on 72 patients with thoracic and upper aerodigestive malignancies (T&UAM) treated with sequential or concurrent RT-CT or RT alone. All patients received prophylactic gln powder 15 g bid for the full duration of treatment. The severity of acute radiation toxicities was graded according to the RT Oncology Group/European Organization for Research and Treatment of Cancer criteria. Primary endpoints were the incidence of grade >2 toxicities, weight loss and requirement for analgesics, and the secondary endpoint was the association of the length of irradiated esophagus from treatment planning with the use of opioids. The incidence of adverse effects was as follows: Grade >2 stomatitis, 25.0%; esophagitis, 60.5%; dysphagia, 54.2%; pain, 25.4%; mycosis, 40.8%. Stomatitis grade >2 was more frequent in patients with head and neck tumors (P<0.001) and in those with prior surgery (P<0.001). Esophagitis (P=0.020) and dysphagia (P=0.008) grade >2 were more frequent in patients with concurrent RT-CT. Regarding analgesics, 9.9% of patients received no pain treatment, 56.3% received simple analgesic therapy and 33.8% opioids. Patients on opioid therapy had a greater mean length of irradiated esophagus (P=0.024) or length >12 cm (P=0.018). In 54.2% of patients, weight loss was observed, particularly with concurrent RT-CT (P=0.007). Thus, the use of oral gln may have an important role in reducing acute radiation toxicities and weight loss, and in lowering the requirement for analgesics in patients with T&UAM. Further randomized trials are required to identify the appropriate gln dose, duration of treatment and precise radiation dosimetric parameters in this group of patients. The present clinical trial was retrospectively registered in the ClinicalTrials.gov Protocol Registration and Results System (registration no. NCT05054517/22-09-2021).

Management of cancer pain with analgetic adjuvant and weak opioid in prostate cancer bone metastases: A case series

BACKGROUND

In cancer patients, cancer pain is the most common cancer complication. About 60-90% of patients with advanced stage cancer experience various levels of pain, and about 30% of patients have been suffering from persistent severe pain. Bones are the most frequent targets of metastases in patients with cancer such as breast, prostate, lung, kidney, and thyroid. In advanced prostate cancer, bone metastasis leads to bone pain, skeletal fracture, and increased mortality. At least 75% of patients with bone metastasis experience bone pain.

CASE DESCRIPTION

We report three cases of cancer pain, treated with primary cancer from the prostate metastasis to the spine. All three patients had lower back pain that radiated to the left and right limbs, with mixed pain and bone pain, where early hospital admission shows the Numeric Rating Scale (NRS) pain scale 9-10. Treated with administration of adjuvant therapy (Gabapentin) and weak opioids (injections of Tramadol) as well as injections of Metylprednisolone (for 3 days), the patient's pain scale was evaluated, and the average NRS obtained on days 2-4 was 5-6. On day 5-8, treatment continued with Gabapentin and Tramadol injections, and the pain scale (NRS) decreased to 2-3. All patients on the 8-9th day of treatment also received Biphosphonates to reduce pain, bone damage, fracture risk, and blood calcium levels. Patients can be discharged with an oral Gabapentin prescription only.

CONCLUSION

A pain scale (NRS) reduction of >50% is obtained from the initial pain scale in cancer pain patients treated using a combination of adjuvant therapy and weak opioids.

Cyclic derivative of morphiceptin Dmt-cyclo-(D-Lys-Phe-D-Pro-Asp)-NH2(P-317), a mixed agonist of MOP and KOP opioid receptors, exerts anti-inflammatory and anti-tumor activity in colitis and colitis-associated colorectal cancer in mice

Endogenous opioid system is involved in the maintenance of the intestinal homeostasis. Recently, we proved that stimulation of opioid receptors using P-317, a cyclic morphiceptin analog, resulted in the alleviation of acute colitis in mice. The aim of the current study was to assess the effect of P-317 during colitis and colitis-associated colorectal cancer in mice. Colitis was induced by addition of dextran sodium sulfate (DSS) into drinking water. Colitis-associated colorectal cancer was induced by a single intraperitoneal injection of azoxymethane (AOM) and subsequent addition of DSS into drinking water (week 2, 5, 8). During macroscopic damage evaluation the samples were collected and used for biochemical (MPO activity assay), molecular (qPCR and western blot) and histological studies. In experimental colitis, P-317 induced an anti-inflammatory response as indicated by macroscopic and microscopic scores. In the colitis-associated colorectal cancer model, a significant difference in colorectal tumor development was observed between vehicle- and P-317-treated mice. P-317 decreased the total number of colonic tumors and inhibited MPO activity. Hematoxylin and eosin staining confirmed anti-tumor activity of P-317. The expression of TNF-α was decreased in P-317-treated mice as compared to the vehicle-treated group. P-317 decreased proliferation as well as β-catenin expression in tumors. P-317, a mixed MOP and KOP receptor agonist, induced an anti-inflammatory response in experimental colitis and decreased tumor development in colitis-associated colorectal cancer in mice.

Laser-photobiomodulation on experimental cancer pain model in Walker Tumor-256

CONTEXT

Cancer Pain is considered a common and significant clinical problem in malignant neoplasms, comprising 20% to 50% of all patients with tumor progression. Laser photobiomodulation (L-PBM) has been used in a multitude of pain events, ranging from acute trauma to chronic articular. However, L-PBM has never been tested in cancer pain.

OBJECTIVES

Evaluate hyperalgesia, edema, COX-1, COX-2, IL-10, and Bdkrb1 mRNA in low-level laser irradiated Walker-256 tumor-bearing rats.

METHODS

Rat hind paw injected with Walker Tumor-256 (W-256) and divided into six groups of 6 rats: G1 (control) - W-256 injected, G2- W-256 + Nimesulide, G3- W-256 + 1 J, G4- W-256 + 3 Jand G5- W256 + 6 J. Laser parameters: λ = 660 nm, 3.57 W/cm², Ø = 0.028 cm². Mechanical hyperalgesia was evaluated by Randall-Selitto test. Plethysmography measured edema; mRNA levels of COX-1, COX-2, IL-10, and Bdkrb1were analyzed.

RESULTS

It was found that the W-256 + 1 J group showed a decrease in paw edema, a significant reduction in pain threshold. Higher levels of IL-10 and lower levels of COX-2 and Bdkrb1 were observed.

CONCLUSION

Results suggest that 1 J L-PBM reduced the expression of COX-2 and Bdkrb1 and increasing IL-10 gene expression, promoting analgesia to close levels to nimesulide.

The Multifaceted Role of Heme in Cancer

Heme, an iron-containing porphyrin, is of vital importance for cells due to its involvement in several biological processes, including oxygen transport, energy production and drug metabolism. Besides these vital functions, heme also bears toxic properties and, therefore, the amount of heme inside the cells must be tightly regulated. Similarly, heme intake from dietary sources is strictly controlled to meet body requirements. The multifaceted nature of heme renders it a best candidate molecule exploited/controlled by tumor cells in order to modulate their energetic metabolism, to interact with the microenvironment and to sustain proliferation and survival. The present review summarizes the literature on heme and cancer, emphasizing the importance to consider heme as a prominent player in different aspects of tumor onset and progression.