ALBERT

Description: Background: The phase 3 double-blind, CALGB/Alliance 100104 study assessed the efficacy and safety of lenalidomide (LEN) or placebo maintenance therapy until relapse in post-autologous stem cell transplantation (ASCT) patients with newly-diagnosed multiple myeloma (NDMM). Interim analyses demonstrated superiority for LEN versus placebo for time to progression (TTP), thus meeting the primary TTP endpoint of the trial. The study was unblinded in December 2009 and, based on the TTP and overall survival (OS) benefit observed with LEN, patients in the placebo arm (who had not yet progressed) at the time of unblinding were given the option of crossing over to receive LEN. Data have been reported for a follow-up of 91 months based on the planned intention to treat (ITT) analysis, yielding a TTP hazard ratio (HR) 0.57 and an OS difference of HR 0.61 (Holstein SA, et al. Lancet Haematol. 2017;4:e431-42). Crossover to active treatment enabled patients to benefit from LEN maintenance and collection of additional efficacy and safety data; however, crossover can confound the estimates of OS for longer follow-up. We report the results of an analysis adjusted for crossover, thus aiming to provide a more accurate estimate of the survival benefit achieved with LEN maintenance therapy. Methods: Results are reported for an analysis based on an updated data cutoff, post-October 2016. The rank-preserving structural failure time model (RPSFTM) was considered the most appropriate method to adjust for crossover (Robins JM, Tsiatis AA. Commun Stat Theory Methods. 1991;20:2609-31). This method requires that the assumption that the treatment effect is the same for patients who receive LEN at randomization as those who receive LEN as crossover treatment is not violated; a landmark analysis was performed to explore this. The iterative parameter estimation (IPE; Branson M, Whitehead J. Stat Med. 2002;21:2449-63) algorithm was used as validation. Both the RPSFTM and IPE analyses assume a residual LEN effect after discontinuation (base case). Results: A total of 76 NDMM patients who had not progressed, as determined by central adjudication, crossed over from placebo to LEN and were included in the analysis. The landmark analysis of OS from the date of unblinding indicated that the treatment effect for the crossover versus the non-crossover placebo group was HR 0.57 (95% confidence interval [CI] 0.29-1.15) (Figure). This also provided a measure of the benefit of LEN maintenance in patients who started maintenance therapy after the trial-specified 90-100 day window post-ASCT (median 11.5 months post-randomization; range 3.2-51.0 months). Adjustment for crossover using the RPSFTM or IPE resulted in an increase in the relative treatment effect of LEN maintenance (vs placebo) on OS from 30.8 months for the ITT analysis (HR 0.61; 95% CI 0.47-0.81) to 40.1 months (HR 0.52; 95% CI 0.36-0.73) for the RPSFTM analysis and 38.8 months (HR 0.52; 95% CI 0.37-0.74) for the IPE analysis (Table). Results were consistent across the two methods. Discussion: This analysis was performed on an updated version of the data set reported in the Holstein article. Once we adjusted for crossover, depending on the methodology used, there was an additional gain of ~40 months of OS. Previously, a pre-planned, pooled meta-analysis of 3 studies that included CALGB/Alliance (McCarthy PL, et al J Clin Oncol. 2017;35:3279-89) indicated that the OS gain was 2.5 years; however, our analysis from the CALGB study alone shows that LEN maintenance may provide a survival benefit of 〉 3 years. In diseases where prolonged follow-up is required to demonstrate survival benefits, allowing patients to crossover to active treatment may be important to facilitate this. However, the results should be analyzed appropriately to enable assessment of the value of the therapy. As this analysis indicates, the value of active treatment may be underestimated if adjustment for crossover is not performed. In conclusion, the data reported here provide further insight into the survival benefits of LEN maintenance therapy post-ASCT and support guideline recommendations to offer LEN maintenance therapy to all patients post-ASCT. Support: U10CA180821, U10CA180882, U10CA180820; ClinicalTrials.gov Identifier: NCT00114101. Disclosures McCarthy: Bristol Myers Squibb: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Takeda: Consultancy, Honoraria. Richardson:Amgen: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees. Cooper:Celgene: Consultancy; BresMed Health Solutions Ltd: Employment. Saunders:Celgene: Consultancy; BresMed Health Solutions Ltd: Employment. Dhanasiri:Celgene: Employment, Equity Ownership. Anderson:Bristol Myers Squibb: Consultancy; Millennium Takeda: Consultancy; C4 Therapeutics: Equity Ownership, Other: Scientific founder; Celgene: Consultancy; OncoPep: Equity Ownership, Other: Scientific founder; Gilead: Membership on an entity's Board of Directors or advisory committees. Stadtmauer:Celgene: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Takeda: Consultancy. Holstein:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Description: Introduction: Inotuzumab ozogamicin (InO), is a novel anti-CD22 antibody-calicheamicin conjugate approved in R/R B-ALL due to its high hematologic remission rate (81%) based on the phase 3 INO-VATE trial comparing to investigators choice (IC). The TOWER trial demonstrated the efficacy and safety of blinatumomab (Blina) for treatment of Ph- B-ALL versus IC. The relative effectiveness of InO versus Blina was investigated by applying indirect treatment comparison (ITC) methods. A UK-based cost-effectiveness model (CEM) submitted to the Scottish Medicines Consortium (SMC) explored the impact of treatment differences with regard to mean life years (LY) gained and quality-adjusted life years (QALY). Methods: As R/R ALL is a terminal disease if left untreated, achievement of complete response/complete response with incomplete count recovery (CR/CRi) in conjunction with stem cell transplant (SCT) is essential for long-term survival. The three most important outcomes related to treatment are thus the level of response determined by CR/CRi, the rate of SCT, and overall survival (OS). Without potentially curative therapy such as SCT, there is no evidence to suggest long-term survival is possible. Therefore, to compare InO to Blina, comparisons of these outcomes were explored using patient-level data from the INO-VATE ALL trial and aggregate data from the TOWER trial. The CEM structure contained four health states categorising patients based on 'No CR/CRi & no SCT', 'CR/CRi and no SCT' and patients receiving SCT ('SCT/Post SCT') - with progression-free survival (PFS) and OS modelled within these states. States were clinically validated as relevant to treatment of the disease. Death was the fourth health state. Different methods were incorporated to allocate Blina patients to the respective health-states. For levels of response (CR/CRi) and SCT a matching-adjusted indirect comparison (MAIC) and a Bucher ITC were explored. As CR/CRi and SCT rates are not mutually exclusive, a multinomial ITC was also conducted. Once allocated into respective health states, OS and PFS were modelled. Three ITC methods were used to compare OS; a simulated treatment comparison (STC), MAIC and a standard network meta-analysis. In the absence of PFS data for Blina, PFS was assumed to have the same relative treatment effect as OS. Quality of life data within the model for the 'No CR/CRi & no SCT' and 'CR/CRi and no SCT' were informed from InO trial data, while SCT quality of life was informed from the literature with time-varying utilities. Costs were incorporated from a UK perspective using 2017 sources and were those submitted to the SMC. Results were annually discounted at 3.5%. Results: Health state proportions for Ph- InO patients were used as the basis to estimate corresponding Blina proportions and show 49.3% of patients treated with InO reach SCT. With higher odds for CR/CRi and SCT for InO, the ITC results consistently indicate Blina leads to lower proportions of patients receiving SCT (19.1-22.5%) and CR/CRi (25.2-33.3%). ITCs comparing OS outcomes for InO versus blinatumomab show negligible differences between treatments, consistently across the three methods. All combinations of the various methods were explored using the list price for both treatments. The results of the CEM ranged from 0.91-1.14 incremental QALYs for InO versus Blina, while LYs ranged from 2.03-2.59 resulting from higher rates of SCT. The incremental cost-effectiveness ratio (ICER) ranged from £3,700 to £7,010 for InO versus Blina. Extensive scenario analysis indicates that InO is a cost-effective option compared to Blina at a willingness to pay threshold of £20,000 per QALY. The SMC recommended InO as a cost-effective use of resources citing an ICER of £6,754 in the CEM when using the MAIC; InO was associated with a mean survival gain of 〉29 months over Blina corresponding to this ICER. Conclusions: Outcomes from the ITC indicate that InO provides patients with a greater probability of achieving CR/CRi and/or receiving a subsequent SCT versus Blina. As CR/CRi followed by SCT are essential for long-term survival and potential cure, the mean OS gain in the model cited in the SMC recommendation is intuitive as it aligns with the superior CR/CRi and SCT odds ratios associated with InO. Further research is required to determine the long-term PFS and OS following SCT in R/R B-ALL, beyond what can be reliably captured within clinical trials. Disclosures Critchlow: BresMed Health Solutions Ltd.: Consultancy. Cooper:BresMed Health Solutions Ltd.: Consultancy. van Oostrum:Ingress Health: Employment; Pfizer: Consultancy; Merck: Consultancy; Janssen: Consultancy; AstraZeneca: Consultancy. Welch:Pfizer Inc: Employment, Equity Ownership. Russell-Smith:Pfizer: Employment, Equity Ownership.