On December 19, 2023 Starpharma (ASX: SPL, OTCQX: SPHRY) reported positive final results from the completed Phase 2 clinical program of DEP docetaxel (Press release, Starpharma, DEC 19, 2023, View Source;mc_eid=bf52dd3418 [SID1234638657]). The clinical program included a monotherapy arm and two combination arms. The Phase 2 trial objectives were met, with endpoints demonstrating encouraging anti-tumour activity of DEP docetaxel when administered as a monotherapy or in combination with other anti-cancer agents, nintedanib or gemcitabine, in multiple advanced, metastatic cancers, including pancreatic, gastro-oesophageal, non-small cell lung cancer (NSCLC) and cholangiocarcinoma.
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The safety and tolerability of DEP docetaxel were also confirmed, with DEP docetaxel demonstrating an improved tolerability profile versus conventional docetaxel in terms of key adverse events, including myelosuppression (severe neutropenia), oedema (fluid retention), alopecia (hair loss) and allergic reactions (anaphylaxis/hypersensitivity).
Developed by Starpharma, DEP docetaxel is a patented, dendrimer nanoparticle version of the chemotherapy drug docetaxel (Taxotere[1]), which achieved peak sales of US$3.1B before patent expiry and is widely used for the treatment of a number of common cancers, including lung, gastro-oesophageal, head and neck, breast, and prostate.
The clinical trial also demonstrated the ability of DEP docetaxel to effectively target tumours, with treated patient biopsies showing that tumour tissue achieved tissue levels of docetaxel up to 60 times higher than levels in blood (Figure 1). This tumour targeting effect was demonstrated across multiple cancer types. These findings confirm the ability of DEP to increase the delivery of drug to tumours, as also demonstrated in multiple preclinical models.
Commenting on the results, Starpharma CEO, Dr Jackie Fairley, said:
"We are pleased to announce positive results of the Phase 2 clinical program for DEP docetaxel. This product has shown encouraging results in multiple difficult-to-treat cancers, both as a monotherapy and in combination with gemcitabine or nintedanib. DEP docetaxel also demonstrated lower rates of key adverse events, including severe neutropenia, hypersensitivity, fluid retention and hair loss, all of which are problematic side effects for patients treated with conventional docetaxel. In the trial, DEP docetaxel achieved clinically meaningful disease control in multiple patients with advanced metastatic cancer who had no other treatment options available.
"These clinical findings, in addition to Starpharma’s recently reported results from the DEP cabazitaxel and DEP irinotecan programs, will feed into Starpharma’s ongoing commercial discussions for the products. These discussions will continue at the upcoming JP Morgan Healthcare Conference in San Francisco in January 2024, in which Starpharma will participate.
"Starpharma would like to thank the patients who participated in the DEP docetaxel clinical trial program, as well as their families, caregivers, and the investigators and other clinical staff for their involvement in the program."
DEP Docetaxel Efficacy Results
The Phase 2 clinical trial program enrolled a total of 80 patients with advanced metastatic cancers who were heavily pre-treated with up to 9 prior lines of therapy (median 3) and up to 37 cycles of prior anti-cancer treatments (median 5), and/or had exhausted all available treatment options.
DEP docetaxel achieved encouraging anti-tumour activity in multiple advanced, metastatic cancers, including pancreatic, gastro-oesophageal, NSCLC and cholangiocarcinoma, despite the advanced nature of most patients’ disease.
A number of these tumours, particularly pancreatic and gastro-oesophageal cancers, represent significant unmet medical needs, and have a very poor prognosis and limited available treatments currently. All patients in the DEP docetaxel trial program had failed to respond to or progressed following prior cancer treatment, including taxanes, platinum-based therapy, or immuno-oncology agents.
In patients with advanced gastro-oesophageal cancer, DEP docetaxel monotherapy achieved a disease control rate[2] (DCR) of 28.6% with disease control for up to 28 weeks in evaluable[3] patients.
In advanced, metastatic non-small cell lung cancer (NSCLC) patients, DEP docetaxel administered in combination with nintedanib (Vargatef) achieved a DCR of 80.0%, with disease control for up to 24 weeks.
DEP docetaxel administered in combination with gemcitabine (Gemzar) in advanced pancreatic cancer patients demonstrated a 75.0% disease control rate (DCR) with disease control for up to 23 weeks. These patients had failed standard-of-care therapy and exhausted all available treatment options prior to enrolment into the trial. DEP docetaxel, administered as monotherapy to advanced pancreatic cancer patients, exhibited a disease control rate (DCR) of 33.3% and reductions in tumour lesions of up to 55.6%.
DEP docetaxel in combination with gemcitabine also demonstrated disease control in other difficult-to-treat advanced cancers, including intrahepatic cholangiocarcinoma and uterine sarcoma, with durable responses for up to 30 weeks. DEP docetaxel monotherapy treatment also achieved encouraging efficacy responses in other rare and difficult-to-treat advanced cancers, including melanoma of the eye and ameloblastoma, with disease control for up to 46 weeks.
The clinical trial also demonstrated the ability of DEP docetaxel to effectively target human tumours, with treated patient biopsies showing that tumour tissue achieved tissue levels of docetaxel that were up to 60 times higher compared to blood (Figure 1). This tumour targeting effect was demonstrated across multiple cancer types.
DEP Docetaxel Safety and Tolerability
DEP docetaxel also achieved a favourable safety and tolerability profile compared with conventional docetaxel with respect to a number of that product’s "Black Box" safety warnings regarding serious, life-threatening adverse events and other dose-limiting adverse events.
DEP docetaxel exhibited reduced rates compared with conventional docetaxel for several such "Black Box" adverse events, including neutropenia and febrile neutropenia, hypersensitivity and peripheral oedema (fluid retention), as well as problematic adverse events, including mucositis (mouth ulceration), nail disorders and hair loss (alopecia).
DEP docetaxel, when administered as monotherapy or in combination with nintedanib or gemcitabine, demonstrated a marked reduction in bone marrow toxicity (myelosuppression), including fewer reports of severe (≥ grade 3) neutropenia (0% for DEP docetaxel monotherapy and 2.5% of DEP docetaxel patients overall) and no cases of febrile neutropenia. This contrasts with conventional docetaxel, where virtually all patients experience neutropenia, and 75 to 85% experience severe (grade 4) neutropenia1.
Lower rates of myelosuppression in DEP docetaxel-treated patients also resulted in fewer instances of anaemia compared to conventional docetaxel. Conventional docetaxel (60 mg/m2) results in anaemia in more than 65% of patients, whereas only 8.0% of patients receiving DEP docetaxel monotherapy and 10% of patients overall experienced anaemia (all grades)1. DEP docetaxel-treated patients (monotherapy) experienced ≥ grade 3 anaemia at a rate of only 4.0%.
The conventional docetaxel formulation (e.g., Taxotere) contains toxic excipients, including detergent-like polysorbate-80 and ethanol, which are associated with severe hypersensitivity reactions, including sometimes fatal anaphylaxis. To reduce the risk of these reactions, patients receiving conventional docetaxel must undergo corticosteroid (cortisone) pre-treatment. Despite this steroid pre-treatment, approximately 15 to 20% of patients receiving conventional docetaxel still experience hypersensitivity reactions, with 2 to 4% experiencing severe allergic reactions or anaphylaxis1. Severe allergic reactions or anaphylaxis can be life-threatening and are the subject of an FDA "Black Box" warning for Taxotere.
Starpharma’s DEP docetaxel is a detergent-free, aqueous formulation that contains no toxic excipients, reducing the risk of hypersensitivity and anaphylaxis. Therefore, it does not require any corticosteroid pre-treatment. There were no cases of hypersensitivity reactions or anaphylaxis reported in the DEP docetaxel trial program, even without steroid pre-treatment.
Peripheral oedema is also a common and serious side effect of conventional docetaxel treatment (Taxotere), with 30 to 50% of patients experiencing it despite steroid pre-treatment1. However, even in the absence of steroid pre-treatment, only 6.3% of DEP docetaxel patients experienced peripheral oedema, and the events were mainly mild to moderate (grade 1/2).
DEP docetaxel treatment was also associated with significantly lower rates (3.8%) of oral mucositis (mouth ulcers) and no cases of severe mucositis. This incidence is much lower than for conventional docetaxel treatment, where these painful events are frequently observed (26% to 53% of patients), with up to 8% of cases experiencing severe mucositis, which can result in the dose reduction, discontinuation or delay of treatment1.
Moreover, alopecia (hair loss) was notably absent following DEP docetaxel monotherapy and only 2.5% overall (monotherapy and combination). This distressing side effect is frequently observed (56 to 76% of patients) with conventional docetaxel treatment1. In addition, a significant proportion of patients (approximately 10%) treated with Taxotere regimens have been reported to experience permanent hair loss4.
Overall, the DEP docetaxel Phase 2 trial program demonstrated encouraging anti-cancer activity and clinically meaningful responses in a range of difficult-to-treat cancers in heavily pre-treated, advanced, metastatic cancer patients who had failed or progressed on prior therapies. DEP docetaxel, when used in combination with either nintedanib or gemcitabine, demonstrated particularly encouraging anti-cancer activity in non-small cell lung cancer and pancreatic cancer, respectively. DEP docetaxel also demonstrated safety and tolerability benefits in key dose-limiting treatment-related adverse events, such as severe neutropenia, compared to published data on conventional docetaxel.
Additional Trial Information
The DEP docetaxel Phase 2 trial program employed a multi-centre, open-label trial design to assess the safety and, tolerability and preliminary efficacy of DEP docetaxel in patients with advanced, metastatic solid tumour cancers. The objectives of Phase 2 were to further explore the anti-tumour efficacy of DEP docetaxel in selected patient cohorts, and to further characterise the safety and tolerability of DEP docetaxel.
A total of 80 patients with advanced solid tumours were enrolled and treated with DEP docetaxel as a monotherapy or in combination with nintedanib or gemcitabine. Patients were enrolled across seven trial sites in the UK, including Guy’s Hospital London, University College London Hospital (UCLH), St James University Hospital in Leeds, Newcastle Freeman Hospital, The Christie Hospital in Manchester, The Beatson West of Scotland Cancer Centre in Glasgow, and Velindre Cancer Centre in Cardiff.
The Phase 2 trial efficacy and safety outcomes are based on results from 80 enrolled patients with advanced solid cancers. These cancers include pancreatic (N=21), gastro-oesophageal (N=15), lung (small cell and non-small cell; N=21) and small numbers of other advanced, hard-to-treat, rarer cancer types such as cholangiocarcinoma, melanomas, gastro-intestinal tumours, and sarcomas.
DEP docetaxel was administered intravenously (IV) once every three weeks (Q3W) at either 45 or 60 mg/m2 docetaxel as a monotherapy or in combination with nintedanib at 200 mg twice daily from day 2 to 21. In the DEP docetaxel and nintedanib combination arm, only advanced, metastatic non-small cell lung cancer (NSCLC) patients (N=13) were treated, in line with the approved indication for docetaxel and nintedanib (Vargatef[5]). For the DEP docetaxel and gemcitabine combination, docetaxel was administered at either 33 or 45 mg/m2 and 800 or 1000 mg/m2 gemcitabine; patients received gemcitabine immediately following DEP docetaxel on Day 1 and Day 8 of the 21 day / 3 weekly (Q3W) dose cycle.
Efficacy was assessed by radiographic imaging (CT [computerised tomography] scans) of tumours evaluated according to the Response Evaluation Criteria in Solid Tumours (RECIST) (version 1.1). All efficacy response data reported in this announcement are for evaluable patients. Evaluable patients are those that received ≥1 dose cycle of DEP docetaxel and had a CT scan to assess response to treatment at ≥7 weeks after commencement of treatment with DEP docetaxel.
Tumour biomarkers, such as CA19-9, were also assessed as a measure of anti-tumour activity, where applicable. Treatment of patients with DEP docetaxel continued until their disease progressed or worsened, or withdrawal for other reasons (e.g., COVID-19). However, if the treating investigator determined that clinical benefits, such as reduced pain or improved symptoms, were being derived from the treatment, patients had the option to continue treatment beyond disease progression.
All adverse events (AEs) reported for DEP docetaxel are also reported for conventional docetaxel (Taxotere).
Almost 90% of treatment-related AEs were mild (grade 1, 57.7%) or moderate (grade 2, 30%), with very few severe (≥ grade 3, 11.5%) events. AEs were generally well tolerated and manageable. The AEs observed (all grades) in ≥10% of all DEP docetaxel-treated patients in Phase 2 include fatigue (47.5%), nausea (42.5%), vomiting (25.0%), diarrhoea (20.0%), decreased appetite (23.8%), peripheral neuropathy (46.3%), arthralgia (13.8%), myalgia (15.0%), dyspnoea (10.0%) anaemia (10.0%) and thrombocytopenia (11.3%). Note: Patients in this study were heavily pre-treated with other anti-cancer therapies, including platinum drugs, which cause both severe myelosuppression and residual neurological toxicity (PN) and predispose patients to recurrence of these AEs with future treatments.
About DEP docetaxel
Developed by Starpharma, DEP docetaxel is a patented, dendrimer nanoparticle version of the chemotherapy drug docetaxel (Taxotere1), which achieved peak sales of US$3.1B before patent expiry and is widely used for the treatment of a number of common cancers, including lung, gastro-oesophageal, head and neck, breast, and prostate. Unlike conventional docetaxel, DEP docetaxel is an aqueous formulation, does not contain toxic detergent-like excipients associated with anaphylaxis, and avoids the need for steroid pre-medication. In both preclinical and clinical studies, DEP docetaxel has demonstrated an improved side effect profile in terms of key adverse events, including myelosuppression, oedema (fluid retention), alopecia (hair loss) and allergic reactions (anaphylaxis/hypersensitivity).