ASCO round up: Zytiga shines in frontline prostate role, Loxo and Incyte pass early tests

While ASCO often showcases the benefits of new cancer therapies, it was a well-established drug that proved to be a talking point at this year’s conference in Chicago.

Data from the UK consortium-run STAMPEDE trial showed Zytiga (abiraterone) plus prednisone, was beneficial to men who are newly diagnosed with advanced prostate cancer.

Results of a previous arm of this trial showed the benefits of giving men diagnosed with advanced prostate cancer docetaxel chemotherapy alongside hormone injections.

The trial involved more than 1,900 patients, with half treated with hormone therapy, while the other half received hormone therapy and Zytiga.

Data from Stampede reported at Asco showed a 37% relative improvement in survival and a 71% improvement in failure-free survival from the addition of Zytiga to androgen deprivation therapy (ADT) in hormone-sensitive prostate cancer (HSPC), in both cases to very high levels of statistical confidence.

According to analysts Evaluate Pharma, this could see Zytiga make up ground on Pfizer's Xtandi.

The results are a boost for the drug, which is only licensed for patients after failure of medical or surgical castration.

Results from the LATITUDE trial, involving later-stage patients, showed a combination of Zytiga with androgen deprivation therapy reduced risk of death by 38% compared with standard therapy.

Radiographic progression free survival was 33 months on Zytiga – an improvement over more than 18 months over the comparator arm.

Incyte drug could be combined with immunotherapy

One of the headlines trends this year is the wave of trials combining PD-1/PD-L1 inhibitors with a huge range of novel immunotherapy agents.

The aim is to enhance and complement the effect of the established drugs, increasing overall response rates and ultimately overall survival - although potentially unacceptable toxicities are a real concern.

Most of these trials are still in their early stages, so few have produced compelling results so far. One significant combination is Incyte’s selective IDO1 enzyme inhibitor epacadostat, Incyte’s in combination with Keytruda (pembrolizumab) in advanced non-small cell lung cancer (NSCLC).

Data presented at ASCO on Saturday showed an ORR of 35% (n=14/40) among all patients with advanced NSCLC treated with the combination, with a complete response (CR) in two patients (5%) and partial response (PR) in 12 patients (30%).

This is significant because comparable response rates seen in Keytruda is 18% and 20% in Bristol-Myers Squibb’s Opdivo.

Epacadostat is also being studied in combination with BMS’ Opdivo, and a phase 1 of this produced encouraging results in treating head and neck, melanoma, ovarian cancer and colorectal cancer last month.

Incyte is now pushing ahead to begin phase 3 trials of the combination with Keytruda and Opdivo later this year.

Loxo looks to file TRK inhibitor

Meanwhile biotech Loxo Oncology announced it is planning to file results from three clinical trials with worldwide regulators, to support use of its TRK inhibitor, larotrectinib.

The first-in-class therapy showed a 76% objective response rate in tumours have tropomyosin receptor kinase (TRK) fusions, regardless of where they are situated in the body.

This represents a new trend in cancer treatment, where drugs are approved on the basis of the biomarker they target, rather than the location of tumours in the body.

The FDA last month approved Merck’s Keytruda for tumours expressing certain genetic features known as a microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) biomarker.

New data on PARP inhibitors

PARP (poly-ADP ribose polymerase) inhibitors are another closely-watched drug class – and ASCO provided fresh data showing AZ’s ovarian cancer drug, Lynparza (olaparib), could also be used in breast cancer.

Tesaro said early-stage trial data suggested its Zejula (niraparib) could be used in combination with anti-PD1 immunotherapies such as Keytruda, or Bristol-Myers Squibb’s rival, Opdivo (nivolumab).

Pfizer also presented phase 2 data from its PARP inhibitor, talazoparib, which it came to through its acquisition of Medivation last year.

The data showed anti-tumour activity in BRCA1/2-positive advanced breast cancer.