Pharmacotherapeutic group: Antiemetics and antinauseants, serotonin (5-HT3) antagonists; ATC code: A04AA55
Mechanism of action
Netupitant is a selective antagonist of human substance P/neurokinin 1 (NK1) receptors.
Palonosetron is a 5-HT3 receptor antagonist with a strong binding affinity for this receptor and little or no affinity for other receptors. Chemotherapeutic substances produce nausea and vomiting by stimulating the release of serotonin from the enterochromaffin cells of the small intestine. Serotonin then activates 5-HT3 receptors located on vagal afferents to initiate the vomiting reflex.
Delayed emesis has been associated with the activation of tachykinin family neurokinin 1 (NK1) receptors (broadly distributed in the central and peripheral nervous systems) by substance P. As shown in in vitro and in vivo studies, netupitant inhibits substance P mediated responses.
Netupitant was shown to cross the blood brain barrier with a NK1 receptor occupancy of 92.5%, 86.5%, 85.0%, 78.0%, and 76.0% in striatum at 6, 24, 48, 72, and 96 hours, respectively, after administration of 300 mg netupitant.
Clinical efficacy and safety
Oral administration of Akynzeo in combination with dexamethasone has been shown to prevent acute and delayed nausea and vomiting associated with highly and moderately emetogenic cancer chemotherapy in two separate pivotal studies.
Highly Emetogenic Chemotherapy (HEC) study
In a multicenter, randomized, parallel, double-blind, controlled clinical study of 694 patients, the efficacy and safety of single doses of oral netupitant in combination with oral palonosetron was compared with a single oral dose of palonosetron in cancer patients receiving a chemotherapy regimen that included cisplatin (median dose = 75 mg/m2). The efficacy of Akynzeo was assessed in 135 patients who received a single oral dose (netupitant 300 mg and palonosetron 0.5 mg) and 136 patients who received oral palonosetron 0.5 mg alone.
Treatment regimens for the Akynzeo and the palonosetron 0.5 mg arms are displayed in Table below.
Table 2: Oral Antiemetic treatment regimen –– HEC study
| Treatment regimen | Day 1 | Days 2 to 4 |
| Akynzeo | Akynzeo (Netupitant 300 mg + Palonosetron 0.5 mg) Dexamethasone 12 mg | Dexamethasone 8 mg once a day |
| Palonosetron | Palonosetron 0.5 mg Dexamethasone 20 mg | Dexamethasone 8 mg twice a day |
The primary efficacy endpoint was complete response (CR) rate (defined as no emetic episodes, no rescue medication) within 120 hours (overall phase) after the start of the highly emetogenic chemotherapy administration.
A summary of the key results from this study is shown in Table 3 below.
Table 3: Proportion of patients receiving cisplatin chemotherapy responding by treatment group and phase
| | Akynzeo N=135 % | Palonosetron 0.5 mg N=136 % | p-value |
| Primary endpoint | | | |
| Complete response | | | |
| Overall phase§ | 89.6 | 76.5 | 0.004 |
| Major secondary endpoints | | | |
| Complete response | | | |
| Acute phase‡ | 98.5 | 89.7 | 0.007 |
| Delayed phase† | 90.4 | 80.1 | 0.018 |
| No emesis | | | |
| Acute phase | 98.5 | 89.7 | 0.007 |
| Delayed phase | 91.9 | 80.1 | 0.006 |
| Overall phase | 91.1 | 76.5 | 0.001 |
| No significant nausea | | | |
| Acute phase | 98.5 | 93.4 | 0.050 |
| Delayed phase | 90.4 | 80.9 | 0.004 |
| Overall phase | 89.6 | 79.4 | 0.021 |
‡ Acute phase: 0 to 24 hours post-cisplatin treatment.
† Delayed phase: 25 to 120 hours post-cisplatin treatment.
§ Overall: 0 to 120 hours post-cisplatin treatment.
Moderately Emetogenic Chemotherapy (MEC) study
In a multicenter, randomized, parallel, double-blind, active-controlled, superiority study, the efficacy and safety of a single oral dose of Akynzeo was compared with a single oral dose of palonosetron 0.5 mg in cancer patients scheduled to receive the first cycle of an anthracycline and cyclophosphamide regimen for the treatment of a solid malignant tumor. At the time of the study, anthracycline-cyclophosphamide containing chemotherapy regimens were considered to be moderately emetogenic. Recent guidance has updated these regimens to highly emetogenic.
All patients received a single oral dose of dexamethasone.
Table 4: Oral Antiemetic treatment regimen – MEC study
| Treatment regimen | Day 1 | Days 2 to 3 |
| Akynzeo | Akynzeo Netupitant 300 mg Palonosetron 0.5 mg Dexamethasone 12 mg | No antiemetic treatment |
| Palonosetron | Palonosetron 0.5 mg Dexamethasone 20 mg | No antiemetic treatment |
After completion of cycle 1, patients had the option to participate in a multiple-cycle extension, receiving the same treatment as assigned in cycle 1. There was no pre-specified limit of the number of repeat consecutive cycles for any patient. A total of 1450 patients (Akynzeo n=725; Palonosetron n=725) received study medication. Of these, 1438 patients (98.8%) completed cycle 1 and 1286 patients (88.4%) continued treatment in the multiple-cycle extension. A total of 907 patients (62.3%) completed the multiple-cycle extension up to a maximum of eight treatment cycles.
A total of 724 patients (99.9%) were treated with cyclophosphamide. All patients were additionally treated with either doxorubicin (68.0%) or epirubicin (32.0%).
The primary efficacy endpoint was the CR rate in the delayed phase, 25-120 hours after the start of the chemotherapy administration.
A summary of the key results from this study is shown in Table below.
Table 5: Proportion of patients receiving anthracycline and cyclophosphamide chemotherapy responding by treatment group and phase – cycle 1
| | Akynzeo N=724 % | Palonosetron 0.5 mg N=725 % | p-value* |
| Primary endpoint | | | |
| Complete response | | | |
| Delayed phase† | 76.9 | 69.5 | 0.001 |
| Major secondary endpoints | | | |
| Complete response | | | |
| Acute phase‡ | 88.4 | 85.0 | 0.047 |
| Overall phase§ | 74.3 | 66.6 | 0.001 |
| No emesis | | | |
| Acute phase | 90.9 | 87.3 | 0.025 |
| Delayed phase | 81.8 | 75.6 | 0.004 |
| Overall phase | 79.8 | 72.1 | <0.001 |
| No significant nausea | | | |
| Acute phase | 87.3 | 87.9 | N.S. |
| Delayed phase | 76.9 | 71.3 | 0.014 |
| Overall phase | 74.6 | 69.1 | 0.020 |
* p-value from Cochran-Mantel-Haenszel test, stratified by age class and region.
‡ Acute phase: 0 to 24 hours after anthracycline and cyclophosphamide regimen
† Delayed phase: 25 to 120 hours after anthracycline and cyclophosphamide regimen
§ Overall: 0 to 120 hours after anthracycline and cyclophosphamide regimen
Patients continued into the Multiple-Cycle extension for up to 7 additional cycles of chemotherapy. Antiemetic activity of Akynzeo was maintained throughout repeat cycles for those patients continuing in each of the multiple cycles.
The impact of nausea and vomiting on patients' daily lives was assessed using the Functional Living Index–Emesis (FLIE). The proportion of patients with Overall no impact on daily life was 6.3% higher (p value =0.005) in the Akynzeo group (78.5%) than in the palonosetron group (72.1%).
Multiple-cycle safety study in patients receiving either Highly Emetogenic Chemotherapy or Moderately Emetogenic Chemotherapy
In a separate study, a total of 413 patients undergoing initial and repeat cycles of chemotherapy (including carboplatin, cisplatin, oxaliplatin, and doxorubicin regimens), were randomized to receive either Akynzeo (n=309) or aprepitant and palonosetron (n=104). Safety and efficacy were maintained throughout all cycles.
Paediatric population
The European Medicines Agency has waived the obligation to submit the results of studies with Akynzeo in all subsets of the paediatric population in prevention of acute and delayed nausea and vomiting associated with highly emetogenic cisplatin-based and moderately emetogenic cancer chemotherapy (see section 4.2 for information on paediatric use).