Starpharma releases positive DEP® phase 2 interim results in prostate cancer

Melbourne biotech company Starpharma today announced positive interim results from the prostate cancer cohort in its ongoing phase 2 trial of DEP® cabazitaxel. The company showed that 100% of evaluable patients with (Stage IV) metastatic prostate cancer have had efficacy responses, utilising one or more standard measures of disease.

Prostate cancer is the 2nd most common cancer in males globally with 1.4 million new prostate cancer patients diagnosed annually.

DEP® cabazitaxel is a patented, detergent (polysorbate-80) free, nanoparticle version of the conventional cancer drug, Jevtana®, which is a leading oncology agent used to treat advanced prostate cancer. Sales of Jevtana® (conventional cabazitaxel) exceeded US$600 million in 2020. The conventional cabazitaxel formulation (Jevtana®) has two US FDA-mandated 'black box' warnings in relation to neutropenia and severe hypersensitivity, associated with polysorbate-80 in the formulation.

Starpharma's interim results in prostate cancer show that one or more efficacy signals[1] were observed in 100% of patients assessed following DEP® cabazitaxel treatment. Responses included:

• 64% of patients with assessable tumour lesions saw prolonged stable disease and significant reductions in tumour size for up to 36 weeks

• 90% of patients with assessable PSA (Prostate Specific Antigen) tumour biomarker levels had a reduction in PSA, with more than half of these patients achieving a reduction in PSA of at least 50%

• 83% of patients with secondary bone disease exhibited either no progression or an improvement in these lesions

• 56% of patients who were evaluable for all three measures had responses to all three.

These positive interim results are particularly significant given all patients in this cohort had late-stage prostate cancer and had failed multiple anti-cancer treatments (including taxanes), in addition to surgeries and radiation, prior to entering the DEP® cabazitaxel trial.

Patients treated with DEP® cabazitaxel also experienced significantly less severe bone marrow toxicity (myelosuppression), significantly lower rates of severe neutropenia and no instances of neutropenic sepsis, which are all associated with conventional cabazitaxel. Further, the absence of detergent-like polysorbate 80[2] in the DEP® cabazitaxel formulation eliminated the need for prophylactic corticosteroids and antihistamines, with no anaphylaxis or severe hypersensitivity reactions observed. This avoidance of long-term steroid use is attractive, particularly in prostate cancer patients where bone health can be a significant issue.

Professor Anthony Joshua, Study Investigator from the Kinghorn Cancer Centre in Sydney with a focus in prostate cancer commented:

"The trial results to date for DEP® cabazitaxel in heavily pre-treated prostate cancer patients are highly encouraging and indicate the potential of the product compared to standard cabazitaxel. The anti-cancer activity, together with less myelosuppression than standard cabazitaxel and a generally well-tolerated safety profile, mean this novel form of dendrimer-enhanced cabazitaxel represents a useful option for prostate cancer patients, including in older patients in whom DEP® cabazitaxel has been particularly well tolerated."

51 patients have now been recruited across all cancer types in the phase 2 DEP® cabazitaxel trial, which is being conducted at multiple sites in the UK and Australia. Recruitment of a small number of additional patients in ovarian and gastro-oesophageal cancer continues following promising efficacy signals in these tumours. Full results for the trial will be reported separately in the coming months.

DEP® cabazitaxel is one of Starpharma's three clinical stage DEP® assets being developed internally, alongside DEP® docetaxel and DEP® irinotecan. Starpharma's intention is to licence internal DEP® assets following clinical proof-of-concept/phase 2. Starpharma also has a number of partnered DEP® programs including with Merck & Co., Inc., and also a multiproduct DEP® licence with AstraZeneca, which includes the development and commercialisation of AZD0466, a novel Bcl2/xL inhibitor, which is in the clinic.

[1] Efficacy in the prostate cancer cohort in the trial was assessed referencing the applicable aspects of the internationally recognised Prostate Cancer Working Group (PCWG3) guidelines.

[2] Polysorbate 80 is a detergent-like substance, which is used to solubilise insoluble molecules, and which is a component of conventional cabazitaxel products, including Jevtana® and generic forms

Source: Starpharma