New evidence-based adaptive clinical trial methods for optimally integrating predictive biomarkers into oncology clinical development programs

Managing Expectations in the Transition to Proof of Concept Studies

BACKGROUND

As we move away from the traditional chemotherapy era to targeted therapy, the validity of old assessment paradigms associated with therapeutics are being raised in the context of immunotherapy. The old paradigm required elaborating on the toxicity assessment, with no expectation of efficacy in early phase trials. Safety data from Phase 1 and 2 studies with many immunotherapeutics show limited toxicities and draw attention to the need to demonstrate efficacy in the early evaluation of new agents.

METHODS

Literature searches indicate that molecular oncology mechanistic-based agents are being linked with molecular disease status and clinical benefit. Biomarkers and other endpoints are being employed to accomplish this. Perspectives for a meaningful context of integrating biomarkers and clinical trial design are reviewed.

RESULTS

The design and conduct of clinical trials have not been fully adjusted to the new era of personalized oncology, and so we are in transition. A part of this transition is the management of expectations and trial designs that need to be considered relative to preclinical experience in the development of therapeutics. For example, pathological complete response is now considered a surrogate marker for favorable prognosis in breast cancer patients who are treated in the neoadjuvant setting. This surrogate marker is tied to novel agents' mechanistic characteristics with no preclinical counterpart.

CONCLUSION

The old paradigm considers patients equal with similar chances to respond to treatments, but the new paradigm considers patient's heterogeneity, a major fact that informs the design of clinical trials. By linking every treatment to a mechanism of action and to the presence of a specific biomarker, new trials are going to have more subjects who are likely to respond to the treatment.

Targeted therapy: resistance and re-sensitization

The last two decades have witnessed a paradigm shift from cytotoxic drugs to targeted therapy in medical oncology and pharmaceutical innovation. Inspired by breakthroughs in molecular and cellular biology, a number of novel synthesized chemical compounds and recombinant antibodies have been developed to selectively target oncogenic signaling pathways in a broad array of tumor types. Although targeted therapeutic agents show impressive clinical efficacy and minimized adverse effects compared with traditional treatments, the challenging drug-resistant issue has also emerged to limit their benefits to cancer patients. In this regard, we aim to improve targeted therapy by presenting a systematic framework regarding the drug resistance mechanisms and alternative approaches to re-sensitize cancer cells/tissues therapeutically.

Molecular targeted agents--where we are and where we are going

A total of 23 new cancer medicines or indication expansions were approved by the U. S. Food and Drug Administration in 2012. Among these, 12 are new molecular entities (NMEs)—new chemical or biological drugs approved for the first time for oncologic use—and 10 of these NMEs are molecular targeted agents. Among the 10 targeted agents, 4 are anti-angiogenesis agents and 2 are Bcr-Abl pathway inhibitors, targeting well established targets validated by previously approved agents such as bevacizumab (Avastin) or imatinib (Gleevec). Despite this progress, several questions remain: Do these newly approved agents provide sufficient treatment options to manage the broad spectrum of cancers we deal with in the clinic? Where will the next wave of new cancer drugs come from? Where should R&D efforts be invested to continue improve cancer treatment and management, especially for tumor types uniquely prevalent in China? This editorial and the review articles in this special issue of Chinese Journal of Cancer provide an in depth review of the progress and challenges in developing targeted cancer therapies, as well as an outlook of new research areas where near term breakthroughs are expected to overcome some of these challenges.