Making sense of the expanded myeloma treatment landscape

ORLANDO – The moment the Food and Drug Administration approved daratumumab, ixazomib, and elotuzumab in rapid-fire succession over 15 days in November 2015, Dr. S. Vincent Rajkumar’s phone started ringing.

As with other multiple myeloma experts, three common questions kept cropping up:

• For previously untreated patients, should we add bortezomib to lenalidomide plus dexamethasone (Rd) based on the S0777 results?

• For previously treated patients, should we add ixazomib or elotuzumab to Rd?

• Should we add daratumumab to frontline therapy right out of the box?

Daratumumab (Darzalex), ixazomib (Ninlaro), and elotuzumab (Empliciti) are welcome additions to the armamentarium, but the problem with this plethora of riches is that numerous treatments already exist for frontline multiple myeloma, observed Dr. Rajkumar, professor of medicine at the Mayo Clinic in Rochester, Minn.

^{Patrice Wendling/Frontline Medical News}

Dr. S. Vincent Rajkumar

In fact, the National Comprehensive Cancer Network guidelines list 22 possible newly diagnosed myeloma regimens that can be potentially recommended for patients.

“This definitely leads to confusion in the community. And this was the result of the fact that we didn’t have a single, good randomized trial with a survival benefit of a modern therapy against another modern therapy,” Dr. Rajkumar said at the annual meeting of the American Society of Hematology during a joint FDA/ASH symposium on the three newly approved agents.

This quandary was solved at ASH with phase III randomized data from the Southwest Oncology Group S0777 study showing a significant overall survival advantage with a triplet of bortezomib (Velcade), lenalidomide (Revlimid), and dexamethasone (VRd) followed by continuous Rd maintenance compared with Rd alone and ongoing maintenance in untreated patients who did not intend to receive stem cell transplant, he said.

Median overall survival was 75 months for the triplet vs. 64 months for the Rd doublet (hazard ratio, 0.709; two-sided log-rank P = .0250), and median PFS 43 months vs. 30 months (HR, 0.712; one-sided P = .0018), study author Dr. Brian Durie, of Cedars-Sinai Comprehensive Cancer Center in Los Angeles, reported (Abstract 25).

The VRd triplet is already in use in the United States, but based on the S0777 results, many groups, including the Mayo Clinic, have changed treatment guidelines and now “prefer bortezomib, len-dex for frontline therapy, not just in transplant candidates, but also in non-transplant candidates,” Dr. Rajkumar said.

In countries where VRd is not possible, bortezomib, thalidomide, and dexamethasone (VTd) is a second option.

Rd is an appropriate therapy for non-transplant candidates who are frail or aged 75 years or older, he said, adding that there is no need to add bortezomib for patients already on Rd and doing well.

“If your patient is doing well on a doublet, leave them alone,” Dr. Rajkumar advised.

Similarly, for patients with relapsed myeloma who are doing well on Rd, there isn’t “an urgent need” to add ixazomib or elotuzumab, but rather, he said, “We can reserve those for when the patient progresses.”

Ixazomib is approved in combination with Rd after at least one prior therapy, but the oral proteasome inhibitor may have a role in the frontline treatment of standard-risk patients. It is a very simple regimen, just three pills a month, and “the side effect profile is outstanding; virtually difficult to tell who’s taking placebo and who’s taking drug,” Dr. Rajkumar observed.

In addition, some patients may not have access to bortezomib because of insurance reasons or can’t drive to the clinic once a week to get the shot, while others may be too frail to get an intravenous or subcutaneous shot or may have neuropathy.

“For whatever reason, I think it is reasonable to keep in mind that we may have a situation where we can use ixazomib/len-dex in clinical practice if the patient’s best interests so dictate,” he said.

For high-risk patients (deletion 17p or translocations t(4;14), t(14;16), t(14;20), VRd or VTd are obvious upfront choices. Based on four phase II trials and the ASPIRE results in the relapsed and refractory setting, however, the Mayo Clinic has already decided that the recently approved second-generation proteasome inhibitor carfilzomib (Kyprolis) plus Rd is also worth considering.

Adding a monoclonal antibody such as elotuzumab or daratumumab to a VRd triplet or ixazomib, lenalidomide, and dexamethasone (IRd) triplet may be another way to improve outcomes in high-risk patients, who still die with a median overall survival of 3 years, Dr. Rajkumar said. This strategy is already being used in the ongoing SWOG S1211 study.

For maintenance therapy after VRd or VTd and autologous stem cell transplant, he recommended lenalidomide for standard-risk patients and bortezomib-based maintenance for high-risk patients, but said ixazomib-based maintenance with the addition of monoclonal antibodies may also have a role in high-risk patients.