the safety in administration of cannabinoids/cannabinoid-based preparations on

cancer patients (Table 12.2).

12.5.8 Endocannabinoid System, Chemoresistance, and Cancer

Resistance toward chemotherapy is one major limitation in the treatment outcomes

and is a challenge for clinicians in cancer treatment. There are multiple mechanisms

of chemotherapy resistance in cancer which include increased activity of efflux

pumps (such as adenosine-triphosphate dependent transporters) or reduced drug

influx, disruptions in apoptotic signaling pathways, etc. Sensitivity of tumor cells

is altered due to mutations of ABCB1, ABCC1, ABCC2, ABCC3, and ABCG2

(Mansoori et al. 2017). Furthermore, multidrug resistance (MDR) proteins play

pivotal role in chemotherapy resistance in cancer and cause major obstacles in

cancer treatment. For instance, in breast cancer, multidrug resistance protein

1 (MDR1) and breast cancer resistance protein (ABCP OR ABCG2) are the efflux

pumps which are responsible for the resistance against established chemotherapeutic

regimens like paclitaxel and docetaxel (An et al. 2017; Chen et al. 2010). However,

in some cases, autophagy-mediated pathways have been observed as additional

mechanism of acquired resistance toward established chemotherapeutic drugs (Pan

Table 12.2 List of clinical trials investigating the role of cannabinoid receptors in various cancers

S. no.

Title

Trial number

Status

1

Study on cannabinoid receptor expression in

gastrointestinal disease (ClinicalTrials.gov n.d.-g)

NCT02735941

Completed

2

A study of dexanabinol in combination with

chemotherapy in patients with advanced tumors

(ClinicalTrials.gov n.d.-b)

NCT02423239

Unknown

3

A study: Pure CBD as single agent for solid tumor

(ClinicalTrials.gov n.d.-c)

NCT02255292

Unknown

4

Efficacy and safety of dronabinol in the improvement

of chemotherapy-induced and tumor-related

symptoms in advanced pancreatic cancer

(ClinicalTrials.gov n.d.-e)

NCT03984214

Recruiting

5

Phase 1 study of dexanabinol in patients with

advanced solid tumors (ClinicalTrials.gov n.d.-a)

NCT01489826

Completed

6

TN-TC11G (THC + CBD) combination with

temozolomide and radiotherapy in patients with newly

diagnosed glioblastoma (ClinicalTrials.gov n.d.-h)

NCT03529448

Not yet

recruiting

7

Assessment of single doses of oral dexanabinol in

healthy subjects (ClinicalTrials.gov n.d.-d)

NCT02054754

Completed

8

Phase 1 study to evaluate safety and usefulness of an

Ayurvedic cannabis preparation in the perioperative

period in breast and oral cavity squamous cell cancer

(ClinicalTrials.gov n.d.-f)

CTRI/2020/

06/026049

Not

recruiting

194

S. Singh et al.