The results of a study with a new anti-cancer medication for advanced kidney cancer, called batiraxcept, were presented at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, USA this week. Batiraxcept is an AXL receptor tyrosine kinase that has been attached to a human protein called immunoglobulin G1. AXL is found in high amounts in cancer cells and causes cancer spread and resistance to VEGFR targeted therapies. Batiraxcept blocks the action of AXL and prevents the growth and spread of cancer cells. An earlier phase 1b study showed promising outcomes for the combination of batiraxcept plus cabozantinib in patients who had stopped responding to first line treatment.

This study tested: 1. Batiraxcept alone for patients whose cancer keeps coming back and who have no treatment options remaining: 2. Batiraxcept plus cabozantinib in patients who had previously received at least one anti-cancer medication: 3. A triple combination of batiraxcept, cabozantinib and nivolumab in patients who had not received any previous anti-cancer medication.

A total of 46 patients were recruited for the study. Most patients (25) were in the batiraxcept plus cabozantinib group. More patients had intermediate and poor risk kidney cancer in the first two groups (80% and 76%) than in the triple combination group (27%) for first-line treatment. Most patients in the first two groups received previous treatment with immunotherapy (100% and 88%, respectively) and VEGFR TKIs (100% and 40%, respectively).

Patients did not respond to batiraxcept on its own. However, when given in combination with cabozantinib 36% of patients had a complete or partial response to treatment. This increased with the triple combination to just over half of the patients having a complete or partial response to treatment. The time to when the treatment stopped working and the cancer started growing again was 1.8 months for batiraxcept alone, 7.2 months for the combination with cabozantinib and 7.6 months for the triple combination with cabozantinib and nivolumab.

The number of reported side effects was highest in the batiraxcept and triple combination groups (80% and 91%, respectively), with 68% of patients in the batiraxcept plus cabozantinib reporting side effects. The most frequent side effects were diarrhoea, extreme tiredness, and problems at the infusion site. The patients who had the triple combination of batiraxcept, cabozantinib and nivolumab had more severe or life-threatening side effects (46%).

The study showed that batiraxcept was well tolerated by the patients but had limited benefit for the patients in terms of improved survival. However, based on these findings the combination of batiraxcept plus cabozantinib will be studied in a phase 3 clinical trial in patients who have stopped responding to previous anti-cancer medication. The current study is looking for an AXL biomarker that can predict whether batiraxcept will be effective in patients who have stopped responding to first-line treatment.

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