By: Len Kusdra, Ph.D., Associate Consultant, Clinical & Scientific Assessment, Kantar Health and Jay Grisolano, Ph.D., Senior Director, Clinical & Scientific Assessment, Kantar Health
In the management of non-Hodgkin lymphoma (NHL), Rituxan® (MabThera in Europe, rituximab, Genentech/Roche)-based therapy forms the foundation for therapy in all settings. This holds true for most subtypes of NHL, including follicular lymphoma (FL), mantle cell lymphoma (MCL), and diffuse B-cell lymphoma (DLBCL). While Rituxan-based therapy is highly effective and leads to improvement in survival rates, patients are rarely cured, and relapse is common, occurring in about 20-30% of patients.
In addition to this clinical challenge of developing resistance to Rituxan-based regimens, Roche/Genentech also face a commercial challenge as the looming patent expiration for Rituxan approaches and the development of biosimilars threatens to steal Rituxan’s market share. Keeping this in mind, the companies developed an aggressive program with Rituxan’s heir apparent, Gazyva® (Gazyvaro in Europe, obinutuzumab, Roche/Genentech), hoping to maintain their hold in the NHL market. Gazyva is a next-generation CD20 inhibitor designed to be a “biobetter” of Rituxan.
This strategy appeared to have paid off when the Phase III GADOLIN (NCT01059630) trial evaluating Gazyva in combination with Treanda® (bendamustine, Teva/MundiPharma/Symbio) in relapsed patients, presented at the 2015 American Society of Clinical Oncology Conference, showed an improvement in progression-free survival (PFS) when patients were treated with Gazyva plus Treanda followed by Gazyva maintenance.1 Based on these results, Gazyva was subsequently approved in February 2016 for the treatment of FL patients who were refractory to Rituxan-based therapy or had relapsed after Rituxan treatment. The approval propelled Gazyva firmly into the NHL space. (Note that Gazyva is also approved for use in combination with chlorambucil as front-line therapy for chronic lymphocytic leukemia, CLL.) With an approval secured in the relapsed/refractory setting, the question became whether Gazyva would be successful in the front-line setting in patients with FL.
Based on the initial results from the Phase III GALLIUM trial (NCT01332968) presented at the Plenary Session on December 4, 2016, at the American Society of Hematology Conference, the answer appears to be an encouraging “Yes.”2 GALLIUM is an open-label Phase III trial evaluating Gazyva in combination with chemotherapy (CHOP, CVP, or Treanda) followed by Gazyva maintenance versus Rituxan plus chemotherapy followed by Rituxan maintenance. A total of 1,202 patients were randomized to receive Rituxan at 375mg/m2 on day 1 of each cycle or Gazyva at 1000mg on days 1, 8 and 15 of cycle 1 and day 1 of subsequent cycles, for either eight 21-day cycles (for CHOP and CVP) or six 28-day cycles (for Treanda). Patients who achieved a complete or partial response at the end of induction received 1000mg of Gazyva (for patients in the Gazyva induction arm) or 375mg/m2 of Rituxan (for patients in the Rituxan induction arm) IV every two months for two years or until progressive disease. GALLIUM met its primary endpoint of investigator-assessed PFS. With a median follow-up of 34.5 months, patients in the Gazyva arm had a statistically significant lower risk of progression or death (HR=0.66; 95% CI: 0.51-0.85, p=0.0012). Similarly, PFS as assessed by an independent review committee showed a statistically significant improvement with Gazyva (HR=0.71; 95% CI: 0.54-0.93, p=0.014). While there was a trend toward an overall survival (OS) benefit with the Gazyva arm, showing a 94% three-year OS rate compared with 92% for the Rituxan arm, the data are not mature enough to determine whether this improvement is clinically significant (HR=0.75, 90% CI: 0.49-1.17, p=0.210). The response rates were also similar between the Rituxan and the Gazyva arms (88.5% for Gazyva plus chemotherapy and 86.9% for Rituxan plus chemotherapy).
A post-hoc analysis stratified by combination regimen showed equal survival benefit with Gazyva regardless of the chemotherapy backbone (HR for Gazyva plus Treanda versus Rituxan plus Treanda=0.61; HR for Gazyva plus CHOP versus Rituxan plus CHOP=0.77; HR for Gazyva plus CVP versus Rituxan plus CVP=0.63). Discontinuation rates between both arms were similar (16.3% for Gazyva and 14.2% for Rituxan), as well as rates of Grade ≥ 3 adverse events (74.6% for Gazyva and 67.8% for Rituxan). The most common Grade ≥ 3 adverse events in the Gazyva arm were neutropenia (43.9%), leucopenia (8.6%), febrile neutropenia (6.9%), and thrombocytopenia (6.1%), which were slightly higher than the Rituxan arm. The rates of Grade 5 adverse events were also similar between both arms (4.0% in the Gazyva arm versus 3.4% in the Rituxan arm).
Results from GALLIUM put Gazyva in a favorable position for a line extension in the front-line setting. Roche and Genentech’s design to allow for physician’s choice of chemotherapy may have been out of practical necessity but will ultimately strengthen Gazyva’s utilization. According to physicians surveyed in the United States, CHOP, CVP, and Treanda are the most common partners used in combination with Rituxan, being utilized in over 80% of patients.3 The clinical benefit seen with Gazyva over Rituxan places it in a strong position to absorb a significant market share that Rituxan currently holds not only in the front-line setting but also in the relapsed setting, thus paving the way for a Gazyva-based therapy to replace Rituxan as standard of care in the future. Collectively, these data may thus provide impetus to use Gazyva upfront, with physicians switching the chemotherapy regimen but maintaining Gazyva as backbone following first relapse.
Despite its strong position, Gazyva faces stiff competition. While GALLIUM showed a PFS benefit of Gazyva over Rituxan, the lack of mature OS data may make physicians reluctant to switch to Gazyva, particularly as Rituxan nears the end of its patent lifespan. This may give time to allow entry of potentially lower-cost rituximab biosimilars to corner a share of the market. Indeed, biosimilars of several other branded products have already begun to make entry into the United States with the recent approvals of Zarxio® (filgrastim-sndz, Sandoz), Inflectra® (infliximab-dyyb, Pfizer), Erelzi (enterecept-szzs, Sandoz), and Amjevita (adalimumab-atto, Amgen), and while oncology biosimilars have yet to make landfall in the United States, this may change in the near future as physicians become familiar with these agents.
Highlighting the growing threat that biosimilars pose to branded agents, Sandoz announced earlier this year that the European Medicines Agency accepted a Marketing Authorization Application for a biosimilar to Roche’s Rituxan/MabThera in Europe, signaling the coming battle in the oncology space.4 In addition to biosimilars, Gazyva faces additional threats from novel agents such as Imbruvica (ibrutinib, Abbvie), duvelisib (Infinity), and Revlimid (lenalidomide, Celgene) that are being evaluated in combination with Rituxan in the front-line setting in their respective Phase III trials. Of these agents, the strongest threat to Gazyva appears to be Revlimid, showing a robust response rate when combined with Rituxan (98% ORR) in a Phase II trial of FL patients in the front-line setting.5 If the strong response rate seen in the Phase II trial translates into a survival benefit in the Phase III RELEVANCE (NCT01650701) trial, Revlimid with Rituxan will be in a good position to surpass Gazyva’s current lead in the treatment of FL.
For the time being however, Gazyva represents a leap forward in the treatment of NHL, which is good news indeed for patients.